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solution mining evaporation

smi evapor process water evaporation for mining wastewater

smi evapor process water evaporation for mining wastewater

Mining operators need water to make bare rock give up its valuable minerals, however stricter regulations on acid mine drainage, removing metals from process water, and total dissolved solids (TDS) are pushing companies to look for more environmentally friendly solutions.

Often tailing ponds are used to hold large quantities of process water. The evaporation process may be carried out naturally in solar evaporation ponds but this approach is slow and requires a great deal of land area. The cost of constructing additional storage ponds and the added cost of clean up and re-vegetation are often prohibitive.

SMIs Mechanical Evaporation machines can rapidly increase the evaporation process, with up to 14 times more efficiency than space taken by the same area of pond. Our Evaporation Machines are relatively compact, reliable, efficient and portable. There are many benefits to using Mechanical Evaporators:

SMI Evaporative Solutions has served the mining industry for over 20 years. The popular SMI 420B and 420F (our innovative floating design) are frequently used in the mining industry due to their durability, industrial construction, insensitivity to dirty wastewater and flexibility.

evaporation ponds l solution mining l spartan controls

evaporation ponds l solution mining l spartan controls

As the liquid cools, the potash and salt crystals settle to the bottom of the pond. It can be challenging for potash dredge operators to select areas of the pond that contain the most amount of potash based on the pond temperature.

smi evaporative solutions - mining technology | mining news and views updated daily

smi evaporative solutions - mining technology | mining news and views updated daily

SMI Evaporative Solutions is the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess water removal. Designed as an alternative to treatments such as desalination, chemical dosing or reverse osmosis, SMIs evaporation equipment is used to manage water in industries including mining, oil and gas, food processing and power generation. SMIs compact evaporation machines are designed to be easily moved between sites and are available as land and water-based solutions. In addition to evaporators, SMI Evaporative Solutions produces software to fully automate the evaporation process. We produce two types of evaporator water-fracturing evaporators and water-atomizing evaporators and can offer a custom service to create a system which perfectly matches your requirements.

SMI Evaporative Solutions is the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess water removal. Designed as an alternative to treatments such as desalination, chemical dosing or reverse osmosis, SMIs evaporation equipment is used to manage water in industries including mining, oil and gas, food processing and power generation. SMIs compact evaporation machines are designed to be easily moved between sites and are available as land and water-based solutions. In addition to evaporators, SMI Evaporative Solutions produces software to fully automate the evaporation process. We produce two types of evaporator water-fracturing evaporators and water-atomizing evaporators and can offer a custom service to create a system which perfectly matches your requirements.

SMIs compact evaporation machines are designed to be easily moved between sites and are available as land and water-based solutions. In addition to evaporators, SMI Evaporative Solutions produces software to fully automate the evaporation process. We produce two types of evaporator water-fracturing evaporators and water-atomizing evaporators and can offer a custom service to create a system which perfectly matches your requirements.

Our primary focus is finding an evaporation solution that is ideally ideally suited for your specific site layout, water chemistry and geographic location. We achieve this by offering a complete service, including: Detailed analysis of the site and system recommendation based on findings System design and engineering Equipment supply including evaporators, pumps and water supply, electrical supply, automation and valves and sensors Project supervision Complete installation, start-up and commissioning If our product line does not fully meet your requirements we will create a customized system for you. We take pride in ensuring that our customers are supplied with the perfect system, and we will work to ensure the system we supply is completely suited to your site and needs. Floating evaporator with submersible pump SMIs 420F floating evaporator is ideal for industrial and extreme outdoor applications such as mine sites. A form of water-fracturing evaporator, the 420F consists of a floating unit with a 2hp pump supplied by a variable speed drive to provide between 10gpm (40lpm) to over 65gpm (250lpm). To ensure the unit cannot be capsized in severe weather, the 420F has plastic pontoons to keep buoyancy, which are filled with closed-cell foam. The water plume height is also kept low to allow longer operation in high winds. The 420F is built to be sturdy and robust to the elements, and the control panel, motor enclosure, fan blade and manifold are all made in high-quality stainless steel. To make sure cable splicing is not required, the 420F comes with a 200ft (61m) continuous cord, meaning it can be used on a large surface of water without needing to extend the power cable. Specific benefits of the floating evaporator include: 3,600rpm blade rotation (depending on power supply) to provide optimum water droplet distribution for evaporation Average annual evaporation rates between 25% and 60%, with some regions reaching 70% Easy maintenance: no weekly cleaning or greasing required No pre-filtering, no clogged nozzles due to fracturing technology, or filter cleaning required due to large orifice sizes Rugged and durable Available with a chemical-resistant coating for corrosive environments Automatic cut-off in the instance of residue or severe ice Automation software for evaporators SMIs automated evaporation software, SmartH2O, operates the evaporator in response to weather conditions. For sites where the water is corrosive or contains chemicals, we strongly recommend the use of automation software due to the speed and accuracy of its response. SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

If our product line does not fully meet your requirements we will create a customized system for you. We take pride in ensuring that our customers are supplied with the perfect system, and we will work to ensure the system we supply is completely suited to your site and needs. Floating evaporator with submersible pump SMIs 420F floating evaporator is ideal for industrial and extreme outdoor applications such as mine sites. A form of water-fracturing evaporator, the 420F consists of a floating unit with a 2hp pump supplied by a variable speed drive to provide between 10gpm (40lpm) to over 65gpm (250lpm). To ensure the unit cannot be capsized in severe weather, the 420F has plastic pontoons to keep buoyancy, which are filled with closed-cell foam. The water plume height is also kept low to allow longer operation in high winds. The 420F is built to be sturdy and robust to the elements, and the control panel, motor enclosure, fan blade and manifold are all made in high-quality stainless steel. To make sure cable splicing is not required, the 420F comes with a 200ft (61m) continuous cord, meaning it can be used on a large surface of water without needing to extend the power cable. Specific benefits of the floating evaporator include: 3,600rpm blade rotation (depending on power supply) to provide optimum water droplet distribution for evaporation Average annual evaporation rates between 25% and 60%, with some regions reaching 70% Easy maintenance: no weekly cleaning or greasing required No pre-filtering, no clogged nozzles due to fracturing technology, or filter cleaning required due to large orifice sizes Rugged and durable Available with a chemical-resistant coating for corrosive environments Automatic cut-off in the instance of residue or severe ice Automation software for evaporators SMIs automated evaporation software, SmartH2O, operates the evaporator in response to weather conditions. For sites where the water is corrosive or contains chemicals, we strongly recommend the use of automation software due to the speed and accuracy of its response. SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

SMIs 420F floating evaporator is ideal for industrial and extreme outdoor applications such as mine sites. A form of water-fracturing evaporator, the 420F consists of a floating unit with a 2hp pump supplied by a variable speed drive to provide between 10gpm (40lpm) to over 65gpm (250lpm). To ensure the unit cannot be capsized in severe weather, the 420F has plastic pontoons to keep buoyancy, which are filled with closed-cell foam. The water plume height is also kept low to allow longer operation in high winds. The 420F is built to be sturdy and robust to the elements, and the control panel, motor enclosure, fan blade and manifold are all made in high-quality stainless steel. To make sure cable splicing is not required, the 420F comes with a 200ft (61m) continuous cord, meaning it can be used on a large surface of water without needing to extend the power cable. Specific benefits of the floating evaporator include: 3,600rpm blade rotation (depending on power supply) to provide optimum water droplet distribution for evaporation Average annual evaporation rates between 25% and 60%, with some regions reaching 70% Easy maintenance: no weekly cleaning or greasing required No pre-filtering, no clogged nozzles due to fracturing technology, or filter cleaning required due to large orifice sizes Rugged and durable Available with a chemical-resistant coating for corrosive environments Automatic cut-off in the instance of residue or severe ice Automation software for evaporators SMIs automated evaporation software, SmartH2O, operates the evaporator in response to weather conditions. For sites where the water is corrosive or contains chemicals, we strongly recommend the use of automation software due to the speed and accuracy of its response. SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

To ensure the unit cannot be capsized in severe weather, the 420F has plastic pontoons to keep buoyancy, which are filled with closed-cell foam. The water plume height is also kept low to allow longer operation in high winds. The 420F is built to be sturdy and robust to the elements, and the control panel, motor enclosure, fan blade and manifold are all made in high-quality stainless steel. To make sure cable splicing is not required, the 420F comes with a 200ft (61m) continuous cord, meaning it can be used on a large surface of water without needing to extend the power cable. Specific benefits of the floating evaporator include: 3,600rpm blade rotation (depending on power supply) to provide optimum water droplet distribution for evaporation Average annual evaporation rates between 25% and 60%, with some regions reaching 70% Easy maintenance: no weekly cleaning or greasing required No pre-filtering, no clogged nozzles due to fracturing technology, or filter cleaning required due to large orifice sizes Rugged and durable Available with a chemical-resistant coating for corrosive environments Automatic cut-off in the instance of residue or severe ice Automation software for evaporators SMIs automated evaporation software, SmartH2O, operates the evaporator in response to weather conditions. For sites where the water is corrosive or contains chemicals, we strongly recommend the use of automation software due to the speed and accuracy of its response. SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

The 420F is built to be sturdy and robust to the elements, and the control panel, motor enclosure, fan blade and manifold are all made in high-quality stainless steel. To make sure cable splicing is not required, the 420F comes with a 200ft (61m) continuous cord, meaning it can be used on a large surface of water without needing to extend the power cable. Specific benefits of the floating evaporator include: 3,600rpm blade rotation (depending on power supply) to provide optimum water droplet distribution for evaporation Average annual evaporation rates between 25% and 60%, with some regions reaching 70% Easy maintenance: no weekly cleaning or greasing required No pre-filtering, no clogged nozzles due to fracturing technology, or filter cleaning required due to large orifice sizes Rugged and durable Available with a chemical-resistant coating for corrosive environments Automatic cut-off in the instance of residue or severe ice Automation software for evaporators SMIs automated evaporation software, SmartH2O, operates the evaporator in response to weather conditions. For sites where the water is corrosive or contains chemicals, we strongly recommend the use of automation software due to the speed and accuracy of its response. SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

To make sure cable splicing is not required, the 420F comes with a 200ft (61m) continuous cord, meaning it can be used on a large surface of water without needing to extend the power cable. Specific benefits of the floating evaporator include: 3,600rpm blade rotation (depending on power supply) to provide optimum water droplet distribution for evaporation Average annual evaporation rates between 25% and 60%, with some regions reaching 70% Easy maintenance: no weekly cleaning or greasing required No pre-filtering, no clogged nozzles due to fracturing technology, or filter cleaning required due to large orifice sizes Rugged and durable Available with a chemical-resistant coating for corrosive environments Automatic cut-off in the instance of residue or severe ice Automation software for evaporators SMIs automated evaporation software, SmartH2O, operates the evaporator in response to weather conditions. For sites where the water is corrosive or contains chemicals, we strongly recommend the use of automation software due to the speed and accuracy of its response. SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

Specific benefits of the floating evaporator include: 3,600rpm blade rotation (depending on power supply) to provide optimum water droplet distribution for evaporation Average annual evaporation rates between 25% and 60%, with some regions reaching 70% Easy maintenance: no weekly cleaning or greasing required No pre-filtering, no clogged nozzles due to fracturing technology, or filter cleaning required due to large orifice sizes Rugged and durable Available with a chemical-resistant coating for corrosive environments Automatic cut-off in the instance of residue or severe ice Automation software for evaporators SMIs automated evaporation software, SmartH2O, operates the evaporator in response to weather conditions. For sites where the water is corrosive or contains chemicals, we strongly recommend the use of automation software due to the speed and accuracy of its response. SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

SMIs automated evaporation software, SmartH2O, operates the evaporator in response to weather conditions. For sites where the water is corrosive or contains chemicals, we strongly recommend the use of automation software due to the speed and accuracy of its response. SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

SMI provides custom SmartH2O packages designed to match the equipment and needs of your site. These can be split into Basic and Premium packages. A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

A Basic SmartH2O package will stop and start evaporators and pumps in response to changing weather conditions, including wind speed and direction, humidity and temperature. The package typically includes: Master control panel Weather station Mounting pole A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

A Premium SmartH2O package operates in the same way as the basic set-up, but allows the user additional control over the equipment. A range of custom features are available, including: Sensors and controls programming to allow increased evaporation during suitable conditions Data interface to enable communication with site control system Monitoring for water and saline levels, rainfall water flow, rate and pressure External internet access to allow the downloading of data Camera to enable real time views of site locations Custom evaporative solutions from SMI SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

SMI Evaporative Solutions will be happy to work with you to find the ideal solution to your evaporation needs. Having provided systems for mining companies in the US, Australia, Columbia, Chile, Mexico, Bolivia and others, SMI is experienced with a range of climates. To find out more about our evaporation systems, or to learn how we could help your company, please contact us using the details below. White Papers SMI Evaporative Solutions: Why Evaporate? SMI Evaporators are now used to manage water in industrial environments, producing water evaporation rates beyond traditional approaches such as misting heads and irrigation systems. Press Releases SMI Evaporative Solutions Releases Free Brochure on Mining Technology SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess... Company Links www.evapor.com

SMI Evaporative Solutions, the largest manufacturer of industrial mechanical evaporation equipment for controlled environment excess water removal, has released a free brochure detailing their evaporative solutions on Mining Technology.

solution mining - an overview | sciencedirect topics

solution mining - an overview | sciencedirect topics

Solution mining refers to the production of salt (or potash, or other soluble products) by pumping water into subterranean salt deposits, found in many parts of the world, dissolving the salts and pumping the brine to the surface for drying and further use.

Solution mining refers to the production of salt (or potash, or other soluble products) by pumping water into subterranean salt deposits, found in many parts of the world, dissolving the salts and pumping the brine to the surface for drying and further use. A by-product is a huge brine-filled cavern as large as 5million petroleum-barrels (Ratigan 1995). About 60years ago it was realized that these caverns are ideal for storage of large volumes of liquid or gaseous hydrocarbons for long durations. Salt exhibits an extremely valuable characteristic in this respect: it creeps, and small fractures in the cavern walls are therefore self-healing; the cavern is thus air/water-tight (Ratigan 1995). The use of solution-mined caverns for storage is now as important as the production of salt (Fiedelman and Voigt, 1993; Ratigan 1995; Reidy 2010).

The top of the cavern is typically several hundred metres below the earths surface. The cavern is accessed via a borehole containing a hanging tubular, i.e. a pipe string nowadays consisting of a long central pipe and a shorter concentric tube around it, thus creating an annular flow passage. In the cavern, the hydrocarbons lie on top of the brine. To retrieve some hydrocarbons from storage, more brine may be pumped into the cavern via the central pipe, forcing the hydrocarbons out through the annulus. The reverse would be done to store additional amounts of hydrocarbons in the cavern.

The central pipe can be as long as 1 km, with a diameter of 520 in (12.550cm) hence very slender with no other support than the built-in casing at the top. Thus, despite their large diameter, hanging tubulars are quite pliable. It is therefore reasonable to expect that they may be vulnerable to mechanical and flow-induced deformations and perhaps damage. In fact, pipe failures have been reported (Ratigan 2008), although at present the mechanism involved is not clear.

In order to assess the susceptibility of hanging tubulars to flow-induced vibrations and instabilities, research has recently been initiated at McGill University (Jamin 2010; Padoussis 2010b). It was reconfirmed thereby that, in principle, the central pipe is susceptible to flow-induced instabilities at high flow rates for both discharging and aspirating flows. Preliminary results suggest that the same applies for flow in the annulus.

A similar application is that of carbon sequestration or Carbon Capture and Storage (CCS). This involves capturing the CO2 released when fossil fuel is burnt and putting it back to the ground. Various forms of CCS have been proposed. Open ocean storage in underwater sea-valleys is no longer considered feasible, but so-called mineral storage through reaction with Mg or Ca to form carbonates is; permanent storage in depleted oil and gas reservoirs (Anonymous 2008) is also feasible.

The project was to develop and implement a data mining solution to support the business in analysis, investigation and decision making. The company was a manufacturer producing a number of different products for the consumer market. The rationale for the development of this data mining tool was a number of expensive product failures where unforeseen combinations of raw materials, intermediates and manufacturing steps had resulted in scrapped or reworked batches.

The concept of a data mining tool to help the business was originally proposed some years ago as a way to address the difficulties of accessing information from multiple sources (in-house business system, supplier information, processing conditions and analytical results). It was felt that such a tool would help consolidate the information into a single location to enable easier investigations.

A project was eventually proposed on the basis of this original concept with the emphasis on access to data from the business system. A prototype was developed to prove the concept and, after a brief review, the project was fully sanctioned. The implementation was contracted out to a third party supplier.

Implementation of the project proceeded for approximately 9 months at a cost of 1.4 million before any formal review of the output. At this point, it was realized that the project was not going to meet the needs of the users. Essentially, the solution would have required significant manual input of data. It was therefore decided to terminate this phase of the project and review an in-house approach with a focus on adding additional functionality to satisfy the users.

The redeveloped project was re-sanctioned with a slightly revised scope using a combined prototyping/implementation model. In essence, this was a repeat of the initial project with an in-house team established to better reflect the user requirements. This second phase of the project took a further 9 months and incurred costs of approximately 1.5 million to develop and deliver the user requirements. However, it was also ultimately stopped once it was realized that it would not have been possible to consistently and reliably populate the system with the necessary data.

In summary, the project lasted 18 months and incurred costs of 2.9 million through a combination of external and in-house activities. The project was finally terminated when it was clear that the solution would not meet the business objectives.

In situ leaching (ISL), also known as solution mining, involves leaving the ore where it is in the ground and using liquids that are pumped through it to recover the minerals out of the ore by leaching. Consequently there is little surface disturbance and no tailings or waste rock generated. However, the orebody needs to be permeable to the liquids used and located so that they do not contaminate groundwater away from the orebody.

Some ISL mining in the past, notably in the eastern bloc, has occurred in broken rock with insecure containment of fluids, and this has resulted in considerable pollution. ISL mining was first tried on an experimental basis in Wyoming during the early 1960s. The first commercial mine began operating in 1974. About a dozen projects are licensed to operate in the United States (in Wyoming, Nebraska, and Texas), and most of the operating mines were less than 10 years old in the early 21st century. Most are small, but they supply some 85% of the U.S. uranium production. About 16% of world uranium production is by ISL (including all Kazakhstan and Uzbekistan output).

ISL can also be applied to other minerals such as copper and gold. Uranium deposits suitable for ISL occur in permeable sand or sandstones, confined above and below by impermeable strata and below the water table. They may either be flat, or roll frontin cross section, C-shaped deposits within a permeable sedimentary layer. Such deposits were formed by the lateral movement of groundwater bearing oxidized uranium minerals through the aquifer, with precipitation of the minerals occurring when the oxygen content decreased, along extensive oxidation-reduction interfaces. The uranium minerals are usually uraninite (oxide) or coffinite (silicate) coatings on individual sand grains. The ISL process essentially reverses this ore genesis in a much shorter time frame. There are two operating regimes for ISL, determined by the geology and groundwater. If there is significant calcium in the orebody (as limestone or gypsum), alkaline (carbonate) leaching must be used. Otherwise, acid (sulfate) leaching is generally better.

Techniques for ISL have evolved to the point where it is a controllable, safe, and environmentally benign method of mining, which can operate under strict environmental controls and which often has cost advantages. The mine consists of well fields, which are progressively established over the orebody as uranium is depleted from sections of the orebody after leaching. Well-field design is on a grid with alternating extraction and injection wells, each of identical design and typical of normal water bores. The spacing between injection wells is about 30m with each pattern of four having a central extraction well with a submersible electric pump. A series of monitor wells are situated around each mineralized zone to detect any movement of mining fluids outside the mining area. The wells are cased to ensure that liquors only flow to and from the ore zone and do not affect any overlying aquifers. They are pressure-tested before use.

The submersible pumps initially extract native groundwater from the host aquifer prior to the addition of uranium complexing reagents (acid or alkaline) and an oxidant (hydrogen peroxide or oxygen) before injection into the well field. The leach liquors pass through the ore to oxidize and dissolve the uranium minerals in situ.

While uranium production in Australia uses acid leaching of the crushed ore, ISL elsewhere normally uses alkaline leaching agents such as a combination of sodium bicarbonate and carbon dioxide. At Beverley and Honeymoon in South Australia the process is acid leaching, with weak sulfuric acid plus oxygen. The leach solution is at a pH of 2.0 to 3.0, about the same as vinegar.

The pregnant solution from the production wells is pumped to the treatment plant where the uranium is recovered (see Section 1.4). Before the process solution depleted of uranium (i.e., barren liquor) is reinjected, it is oxygenated and if necessary recharged with sulfuric acid, or with sodium bicarbonate or carbon dioxide, to maintain its pH.

Most of the solution is returned to the injection wells, but a very small flow (about 0.5%) is bled off to maintain a pressure gradient in the well field and this, with some solutions from surface processing, is treated as waste. It contains various dissolved minerals such as radium, arsenic, and iron from the orebody and is reinjected into approved disposal wells in a depleted portion of the orebody. This bleed of process solution ensures that there is a steady flow into the well field from the surrounding aquifer and serves to restrict the flow of mining solutions away from the mining area.

In the United States, the production life of an individual ISL well pattern is usually less than 3 years, typically 6 to 10 months. Most of the uranium is recovered during the first 6 months of the operation of those wells. The most successful operations have achieved a total overall recovery of about 80% of the uranium from the ore. Over time, production flows decrease as clay and silt become trapped in the permeable sediments. These can be dislodged to some extent by using higher pressure injection or by reversing the flow between injection and production wells. At established operations in the United States, after ISL mining is completed, the quality of the remaining groundwater must be restored to a baseline standard determined before the start of the operation so that any prior uses may be resumed.

In contrast to the main U.S. operations, the water quality at the Australian sites is very low to start with, and it is quite unusable. At Beverley the groundwater in the orebody is fairly saline and orders of magnitude too high in radionuclides for any permitted use. At Honeymoon, the water is even more saline and high in sulfates and radium. When oxygen input and leaching are discontinued, the water quality soon reverts to its original condition. With ISL, no tailings are involved and very little waste is generated. ISL thus has clear environmental advantages in the places it can be applied.

Salt caverns are artificial cavities in underground salt formations, which are created by the controlled dissolution of rock salt by injection of water during the solution mining process. Geometrical volumes of a few 100 000m3, and up to 1 000 000m3 and more in individual cases, can be achieved depending on technical specifications and geological conditions. In Germany the caverns lie at depths of around (5002000) m, with cavern heights of up to 400m. Depending on the depth, these caverns can be operated with a pressure of up to 200105Pa (200bar) and thus allow the storage of very high volumes of gas. The favorable mechanical properties of the salt enable the construction and operation of extremely large cavities stable for long periods of time, which are also completely impervious to gases. In addition, salt is inert with respect to gases and liquid hydrocarbons. The amount of exploration work required is also usually much lower than the aforementioned aquifer storages because many salt structures are already known from oil and gas exploration and the investigation of salt as a raw material itself. Salt caverns are primarily used for the storage of seasonal reserves, trading storages, and as strategic reserves. Moreover, because they are very flexible with respect to injection and withdrawal cycles, they can also be used to cover daily demand peaks.

Artificially constructed salt caverns have been used for the storage of energy carriers for over 50 yearsprimarily to store fossil fuels such as natural gas, oil, and petroleum products (refined fuels, liquefied gas), but also for the storage of hydrogen and compressed air. Liquefied petroleum gas (LPG) as well as oil were stored in the first caverns in the United States and Europe in the 1950s. The first natural gas cavern was constructed in Marysville, Michigan (United States) in 1961 [31]. The first hydrogen cavern was constructed on Teesside in the United Kingdom in 197172 and is still in operation [32]. Today, there are more than 2000 salt caverns in North America and over 300 salt caverns in Germany used to store energy carriers [33,23].

The distribution of salt deposits worldwide is very localized (Fig.6.6). In Europe, for instance, countries such as Germany, Denmark, and the Netherlands have a large amount of salt, with a great deal of additional expansion and enlargement potential for salt caverns, while other countries have very minor or no potential at all. However, it is feasible that countries with large potential for the construction of salt caverns can create capacities beyond their own national needs as part of an international storage system and thus make them available to other countries.

Most nuclear fuel is produced from uranium by a series of processes including: conversion, enrichment, and fabrication. Yellowcake from the conventional mills, solution mining, and by- product operations is shipped to conversion facilities where is converted to uranium hexafluoride (UF6).

Uranium hexafluoride is a solid at room temperature but forms a gas when heated. In gaseous form, the concentration of the fissionable isotope 235U, can be increased from the natural level of 0.711% to nuclear fuel levels of 3.05.0% by either a diffusion or centrifuge process. In the United States by process of diffusion, gaseous UF6 is passed through a seriesor cascadeof porous membrane filters. Because UF6 molecules containing the U-235 isotope diffuse through the filters more readily than those containing the U-238 isotope, the diffusion process eventually results in two product streams of UF6. Compared to the original feed material, one product stream is relatively enriched in the isotope U-235, and the other is relatively depleted in U-235.

Enrichment of the 235U isotope is necessary because the amount of fissile U-235 in natural uranium is too low to sustain a nuclear chain reaction in light-water reactors. By contrast the 235U content of nuclear weapons is typically in excess of 90%.

At the fuel fabrication plant, the enriched UF6 is converted to uranium dixoide (UO2). The uranium dioxide is compressed into solid, cylinder-shaped pellets, which are placed in hollow rods made of a zirconium stainless steel alloy. These rods, which are grouped into fuel rod assemblies, are shipped to nuclear power plants for use as nuclear reactor fuel. One pound of natural uranium can produce as much energy as about 14,000lb of coal.

Construction involves drilling a well deep into the rock salt with a diameter of d<1m (Fig.19.6). Several pipesso-called casingsare installed in this well in a telescope-like arrangement and bonded with cement to the surrounding rock to make the casings gas tight. Two additional casings are suspended in the well to construct the cavern during the solution-mining process. Water is injected into the inner pipe string to dissolve the salt. The brine which this produces is displaced to the surface through the inner annulus or reverse. A protective fluid (blanket) is injected into the outer annulus to prevent uncontrolled upward solution of the salt formation. The brine produced by solution mining must be disposed of in an environmentally compatible way, for example, by pumping it into the sea. Alternatively, it can be used as a raw material for salt production or by the chemical industry.

Once the cavern has reached its final volume a test is carried out to confirm the tightness of the cemented casings. After a successful test the gas production string is then installed by sealing off the annulus from the inner cemented casing and filling it with a protective liquid (Fig.19.7). In the unlikely event of a leak into this casing, this leaking gas would be immediately detected because this would cause the gas in the fluid to immediately rise upward. This crucial safety feature is supplemented by a subsurface safety valve which closes automatically if the cavern head at the surface becomes damaged. However, before this valve can be installed, the remaining brine in the cavern has to be displaced to the surface via a brine displacement string by the storage gas injected.

Salt caverns for storage have typical geometrical volumes from several 105m3 (100 000m3) to maximum 106m3, and maximum pressures of 200105Pa (200bar). The minimum pressure is around one-third of this, which leads to a favorable working-gas-to-cushion-gas ratio of 2/1.

Salt caverns are particularly suitable for flexible operations with frequent cycles and high injection and production rates because no pressure losses occur within the essentially open storage volume, as would be the case in a rock matrix with pore storage. Rock salt is also impermeable to and does not react with conventional gaseshowever, a certain amount of saturation with water vapor must be expected from the residual brine remaining in the sump of the cavern.

These properties are particularly important for the storage of hydrogen (see chapter 20: Larger Scale Hydrogen Storage) which is very reactive, and which has to remain extremely pure, particularly for its future use as a fuel in hydrogen fuel cells.

A suitable salt formation must be available to construct and operate storage caverns with economically viable volumes. Roughly speaking the following main types occur in nature: salt dome, salt pillow, and bedded salt (Fig.19.8).

The first requirement for a suitable formation is adequate vertical thickness and lateral extent. Adequately thick salt horizons are also required above, below, and adjacent to each cavern to guarantee the stability and tightness of the rock salt surrounding the caverns. With respect to subsequent storage pressures the formation must also be adequately deep but not located at excessive depths. In addition, the salt formation must not contain too large a proportion of insoluble constituents because this could jeopardize the creation of cavities with adequate net volumes. And, finally, the suitability of a location largely also depends on the ability to utilize or to dispose of the brine generated by the solution-mining process: The creation of 1m3 of cavity generates c. 8m3 of brine; this means that around 4106m3 of brine are generated when constructing a cavern with a typical volume of 5105m3 (500 000m3)this brine can be used by industry or disposed of in an environmentally compatible way, for example, into the sea or into deep saline aquifers (Table19.4).

In Table19.4, m3(std) refers to standard cubic meter, which is defined here as the gas mass within a volume of 1cubic metre under a pressure of 1.013105Pa (1.013bar) and at a temperature of 273.15K. Standard conditions are subject to minor national differences; standard cubic meters are commonly used in the oil and gas industry.

The investment costs for storage caverns are typically associated with large starting costs for one-off investments in the necessary geological exploration and infrastructure of the well, and then relatively minor costs for the creation of the actual cavity. Fig.19.9 gives an indication of the specific costs depending on the volume. The usual volumes of several 100 000m3 are associated with costs of around (3050) m3 (geometrical); these costs also depend on whether the cavern is constructed on a greenfield site or a brownfield site, where caverns already exist. These costs do not include filling the caverns with the cushion gas.

The time required for constructing storage caverns can be divided up into the planning phase, the main approval phase, and the construction phase. The time required to construct the cavern itself largely depends on the solution-mining process, which in turn depends on the maximum possible water injection rate (Table19.5).

When planning underground energy storage facilities in future, it is important to remember that the time required for realization can easily involve 10years, even under favorable conditions. The key tasks of natural gas storage in salt caverns are:

Conventional mining involves removing mineralized rock (ore) from the ground, breaking it up, and treating it to remove the minerals. In situ leaching (ISL), also known as solution mining, or in situ recovery, involves leaving the ore where it is in the ground, and recovering the minerals from it by dissolving them, and then pumping the pregnant solution to the surface where the minerals are recovered. Consequently, there is little surface disturbance and no tailings or waste rock are generated. However, the ore body must be permeable to the liquids used, and located such that the liquids do not contaminate the groundwater away from the ore body. ISL can also be applied to other minerals, such as copper and gold, for uranium- and other radionuclide-contaminated soils. ISL techniques were developed where it is a controllable, safe, and environmentally benign method of mining, operating under strict operational and regulatory controls. Due to the low capital costs (relative to conventional mining), it often proves to be an effective method of mining low-grade uranium deposits.

Salt caverns are alternatives to porous storages; see Figure 7.5. The caverns first have to be constructed in the salt formation by injecting water through an access well and dissolving the salt. This so-called solution mining process generates large volumes of brine that must be disposed of in an environmentally compatible way. Because of its visco-plastic properties, rock salt is extremely tight to gases like natural gas or hydrogeneven under high pressure. The enormous open cavities which these caverns represent, with volumes from a few 10,000s to more than 1,000,000m3 at operating pressures of up to 20MPa and more, are particularly suitable for flexible gas operations with high production and injection rates and frequent gas cycles. The proportion of cushion gas is typically 30%. Because of these properties salt caverns are most suitable for the future storage of hydrogen from renewable energy. Rock salt does not react with hydrogen, one key advantage compared to porous reservoirs. However, water from the cavern sump will increase the water vapor content of the stored gas.

Salt caverns allow high injection and withdrawal rates; they are, however, limited by the allowable pressuretime gradient p/t (common maximum value: 1MPa/day). Overstepping this value may damage the integrity of the surrounding cavern walls due to thermo-mechanical stress. Numerical simulations for a 500,000m3 cavern show mass flow rates of up to 11,000kg/h.

Even though hydrogen has been stored in salt caverns successfully in the UK and the USA for many years, to enable this technology to be used in Europe in the future, the technical components of the access wells below and above surface still need to be adapted to present national safety standards.

When comparing the key options for underground gas storage, it becomes obvious for many reasons that salt caverns are the first choice for storing strongly fluctuating wind and solar power. Salt caverns are best suited for flexible operations with high gas injection/withdrawal gradients and frequent turnovers. Furthermore, the share for cushion gas is moderate compared to reservoir storage. Most important, there are no mineralogical or microbiological reactions to be expected. A typical 500,000m3 hydrogen cavern can store approx. 3733 tons (working gas). This corresponds to an energy content of around 124GWh with a maximum power input or output of approx. 0.4GW.

The choice between the common underground storage options of natural reservoirs or man-made salt caverns ultimately depends not only on technical issues but also on the natural geological conditions, which typically vary from region to region.

Methods in biohydrometallurgy are illustrated in terms of commercially relevant bioleaching techniques. Science and technology of industrially adapted bioleaching processes are discussed and relevant laboratory and research approach for the development of such processes analyzed.

Vat leaching Crushed ore/concentrate in submerged leach solution The crushed materials collected in concrete vats. The solution percolates through the ore mass, overflows from a designed weir and pumped to the next vat.

Heap leaching can be grouped among the percolation leaching technologies which also include dump leaching, ISL, as well as vat leaching. In ISL, the ore underground is leached by percolating solutions through natural porosity of rocks or porosity created by blasting and selective fracturing. In dump leaching, the as-mined ore is piled up as dumps and irrigated with leaching solution that percolates through the bed and effluents collected from the base. No crushing is involved before stacking and all sizes of the mined ore ranging from large boulders to few centimeters and more form part of the dump. In heap leaching, the mined ore is crushed to size, usually below 2025mm, and heaps are scientifically prepared and engineered on prepared bottom pads. In vat leaching, more finely crushed ore (110mm) is placed in a large basin (vat) flooded with leachant solution and left to react with time. The solution is drained off after treatment for metal recovery.

Heap bioleaching of different ores is a rapidly developing metal extraction technology because it has a major impact on base and precious metal industries. This technology made initial impact in Chile where acid-soluble copper oxide ores were first heap leached and subsequently secondary copper sulfides were heap bioleached. The process got evolved based on practical operation data acquired over several years of experience both in Chile and Australia. Better operational controls of bioheaps were incorporated with the design of aerated and high temperature heaps with provision for different irrigation systems. Heap bioleaching is now commercially used to treat copper, uranium, and gold ores as well as polymetallic ores containing nickel, zinc, cobalt, and copper. Significant advances have been made in several operational aspects of heap bioleaching, such as agglomeration of crushed ores, inoculation strategies, acid curing, forced aeration, irrigation management, in-heap heat generation, maintenance and control, as well as close monitoring of all parameters controlling leaching kinetics [6]. A simplified heap leach scheme is shown in Fig. 5.1.

Several factors need to be considered for the choice of a heap reaching method depending on the size and mineralogy of the deposit, grade of the ore mineral and transport, power, and labor costs. For example, for low-grade copper oxide ores, conventional heap acid leaching may suffice. However, for lower grade secondary copper sulfides, heap bioleaching is the most likely process route. In recent years, heap bioleach processes are being developed to treat primary copper sulfides such as refractory chalcopyrite. Typical pilot heap for bioleaching of low-grade chalcopyrite ores is shown in Fig. 5.2.

Basic efficiency in a heap leaching process is evaluated in terms of percent metal dissolution and the time required for such dissolution. Metal dissolution is controlled by the degree of liberation of the desired mineral component in the heap, ore particle size, contact between the ore particles, and the lixiviant (heap permeability), leach kinetics based on dissolution mechanisms, dissolution potentials, and composition of minerals and electrolytes, bacterial growth and activity, availability of oxygen and other gaseous reagents, and rate of irrigation. For heap leaching, the mined ore is subjected to size reduction by crushing before stacking on impermeable under liner fitted pads. If the ore is very permeable, little or no crushing may be required, Lixiviant contact with the mineral particles needs to be ensured through efficient percolation. Percolation rate should be slow enough to facilitate necessary contact periods between the ore particles and the lixiviant. Uniform permeability is essential to ensure optimal flow of leach solutions throughout the heap. Whenever excessive fine particles are present in the ore feed, prior agglomeration using binding agents becomes necessary before stacking. The height of the heap also controls consolidation and permeability of the stacked bed. Stacking methods such as the use of conveyers, trucks, or trippers are employed depending on proposed heap designs with respect to consolidation and height [7,8].

Mineral dissolution from the heap depends on nature of the mineral, lixiviant type and concentration, pH, temperature, presence of other cations and anions in solution, oxygen levels, and bacterial activity. The nature and amount of gangue constituents present in the ore feed are very important because they govern the lixiviant (acid) consumption and extent of impurity dissolution. In addition to acid consumption, the presence of gangue constituents such as gypsum, silica, and jarosite has potential detrimental effects as plugging up of pores affecting leach permeability and creating problems in downstream filtration and metal extraction. Heap heights range between 6 and 10m in general cases; however, taller heaps are also constructed [7,8].

Basic components of a heap bioleaching system include agglomerated ore on the heap, lined bottom pad, solution (effluent) collection system, lixiviant solution storage, and recirculation as well as ponds (irrigation systems). Percolation and subsequent drainage of the leach solution is driven by gravity. In flat-bed pads, the internal drainage is fed to collection ponds. In mine valley heap leach pads, downgradient embankment is used for the collection of effluents. Collection of effluents in sumps has multiple base liner systems. Leach pads should be so designed and constructed as to provide:

Ore stacking can be done by conveyor systems or trucks. Truck dumping may cause ore segregation with respect to distribution of coarse and fine particles. Short lifts can cause less segregation. Conveyer stacking systems which are continuously moved as the heap is being built through mechanization are often used [7,8].

Application of leach solution is to achieve complete and uniform ore wetting through continuous percolation between entire ore particles. Solutions can be applied on top surfaces of the heaps through drip irrigation or spray techniques or sprinklers based on climatic conditions. Irrigation ponds on the top surfaces can also be provided suitably. Typical irrigation rates are 520L/m2/hours, while aeration at 0.10.5m3/m2/hours.

Heap leach kinetics involves complex interplay between solution transport to and fro, air solution mass transfer, and migration through stagnant solution in agglomerates and particle porosities. Microbial colonization behavior, desired mineral location and liberation in the heap mass, biooxidation rates, and heat reaction balance also influence heap leach kinetics [7]. Heap leach periods vary depending on the type of ore, and leaching method ranging from a few days to months and even a couple of years. Subprocesses in heap bioleaching have been studied to understand the complex nature of interactions. Four different scales of reactiontransport phenomena have been distinguished [9,10].

Solution flowIn coarse packed beds which are unsaturated, solution flow follows different difficult pathways and remains stagnant in crevices and pores between particle aggregates. Reagent delivery and removal of reaction products from heap inner sites are strongly affected by this phenomenon.

In coarse packed beds which are unsaturated, solution flow follows different difficult pathways and remains stagnant in crevices and pores between particle aggregates. Reagent delivery and removal of reaction products from heap inner sites are strongly affected by this phenomenon.

Microbial mass and population encompasses complex synergetic interactions both in liquid and solid phases. Temperature, O2 and CO2 availability, solution constituents, and concentration influence microbial growth and activity.

However, longer extraction periods are required along with generally lower overall recoveries. The process is further restricted to treat only coarser particles (not fines) through percolation leaching.

The slow rate of metal recovery is a major constraint and heap permeability is a key factor in this regard. Various processes can contribute towards this anomaly, such as the presence of fines and reaction products which can clog-up open pores. Heap effluents are generally very dilute with respect to dissolved metals requiring elaborate concentration, purification, and recovery techniques. Environmental impact also needs to be considered with respect to generation of toxic chemical solutions and solution-seepage. The fate of spent heaps is another area of concern. Spent ore from used-up heaps can be removed and properly disposed in a waste pile. Another way is the reuse of spent heap to stack fresh materials on top.

Biooxidation mechanisms in the heap bioleaching of copper, uranium, zinc, nickel, and gold are illustrated in Chapters 68Chapter 6Chapter 7Chapter 8, Bioleaching of Copper and Uranium, Bioleaching of Zinc, Nickel, and Cobalt, and Biotechnology for Gold Mining, Extraction, and Waste Control, respectively. Also, examples heap bioleach operations around the world for copper, uranium, gold, and multimetal ores are given in Chapters 68 and 11Chapter 6Chapter 7Chapter 8Chapter 11, Bioleaching of Copper and Uranium, Bioleaching of Zinc, Nickel, and Cobalt, and Biotechnology for Gold Mining, Extraction, and Waste Control, and Extended Applications of Metals Biotechnology, respectively, along with different types of heap bioleaching such as Geocoat, Geoleach, and high temperature and ambient temperature heap leaching processes.

Heap bioreactors provide a widely heterogeneous environment for microbial growth. Types of microbial colonies change with change in heap environments with time. Generally, the indigenous organisms attach to ores particles in the heap and grow as biofilms. Extreme conditions often prevailing in heaps influence their microbiology. Microbial consortia existing in pilot and industrial heaps composed of several species having widely different pH and temperature optima and can be generally categorized in terms of mesophiles (24C40C), moderate thermophiles (40C60C) and extreme thermophiles (60C80C). Heaps are thus subject to greater biodiversity with variations in dominant microbial species during different stages of heap operation [11]. Differences between microorganisms that are competitive in a heap environment compared to those in a stirred tank bioreactor can be expected. In stirred tank bioleaching, existing turbulent shear conditions can disrupt bacterial attachment and cell wall integrity, unlike often the case with heap environments.

Due to sulfide mineral oxidation with in heaps, greater temperature biodiversity can be expected [12]. Variations in pH, temperature, aeration, and liquid compositing with time occurring within a heap have a significant effect on the microbial activity and populations. An understanding of microbial flora along with the physico-chemical profiles as a function of time in a heap would be beneficial in controlling biooxidation rates and to take remedial measures whenever microbial activity is getting inhibited. Also, adaptation of leaching microorganisms to heap environmental conditions could effectively enhance metal extraction rates. The development of new molecular biological techniques such as polymerase chain reaction (PCR), real-time quantitative PCR, denaturing gradient gel electrophoresis (DGGE), and fluorescent in situ hybridization have helped to detect and quantify microbial populations to establish heap biodiversity and to monitor changes in microbial consortia without the necessity to culture in situ organisms. A recent development is the rapid determination of active biomass in leach solutions based on ATP concentrations to quantify microbial activity in a simplistic fashion.

Microbiology of heap bioleach systems is generally assessed based on the analysis of liquid samples from pregnant leach liquors and raffinates. In order to gain practical insight into actual microbial activity, it is also essential to enumerate and study activity of particle-attached microorganisms.

Heap bioleaching processes are generally dependent on activities of indigenous microbial colonies. However, to achieve desirable metal extraction within shorter time periods, it becomes essential to promote microbial colonization of desirable organisms with in all cross sections of the heap. The necessity for microbial inoculation from outside thus needs to be considered. An example is heap bioleaching of chalcopyrite which needs to be operated at high temperatures to augment copper dissolution for which organisms that grow and are active over a range of temperatures from ambient to 60C80C are required. Due to the lack of sufficient thermophilic cultures under indigenous environments, it becomes essential to undertake inoculation of desirable microorganisms. Some reported examples of inoculation strategies are indicated below:

Initial inoculation with mesophiles and as the heap temperature increases, moderate thermophiles and when thermophilic conditions are attained, appropriate thermophiles added (for high temperature heaps) [23].

Rather than waiting for indigenous microorganisms to grow in-situ with in a heap, it would be prudent and timely to inoculate a new heap with a chosen microbial consortia at appropriate time intervals [12].

With the reference point as rate of mineral oxidation by a pure culture of one or more chemolithotrophs (e.g., Leptospirillum), additional mixed acidophilic cultures which possess complimentary capabilities as sulfur oxidation or heterotrophic growth are compared.

Use of an inoculum containing a wider variety of various species of acidophiles on the basis that the most suitable among them to a particular mineral (concentrate) will survive, while the unfit ones will be eliminated in the competition.

Preadaptation of leaching microorganisms to increased toxic metal levels and ore or concentrate substrates would be a simpler approach to enhance mineral dissolution kinetics and genetic improvement. Microbial tolerance to high metal and salt concentrations has been studied. Metal toxicity and development of toxic metal tolerant strains of A. ferrooxidans are discussed in Chapter 4, Bioleaching Mechanisms. In heap bioleaching processes, large amounts of undesirable gangue mineral constituents as well as prolonged exposure to recycled solutions containing various cations and anions are encountered. Toxicity of leaching microorganisms to chloride, sulfate, nitrate, and fluoride as well as metal cations such as copper, zinc, nickel, and aluminum (all present together) needs to be ascertained.

Another aspect is the role and activity of mineral attached bacteria compared to unattached planktonic organisms. Impact of bacterial attachment, biofilms, temperature variations, and irrigation rates on microbial activity in heaps needs to be understood.

Dump leaching was initiated during the late 1960s. One of the well-known dump leaching operations is located in Bingham Canyon, Utah (The United States) of the Kennecott Copper mines. The largest of the dumps at this site contained about 4 billion tons of low-grade copper ore. A more recent deliberately built-up dump is the Bala Ley plant, Chuquicamata, (Codelco) in Chile consisting of run-of mine ore piled to 350m height. The dumps are subjected to preconditioning cycles, irrigation, rest periods, and washing stages extending to over a year. Microorganisms indigenously present in the dump dissolve the copper sulfide minerals, and the copper-laden effluents are removed from dump bottom [25].

Dump leaching involves recovery of metal values from lean (submarginal grade) and waste ores generated from open-cast mining operations. Such waste ores were often piled haphazardly near the mine site since ancient times. The uncrushed, fractured ore materials are lifted by trucks or loaders and dumped to form truncated cones at suitable sites in the vicinity. Generally, steep-sided valleys or hill sides are chosen to ensure solution percolation and collection. Schematic illustration of a dump design on hill side or steep valley is shown in Fig. 5.3. Dumps may consist of up to 5m thick alternating layers of coarse lumps and fine-grained rock materials and can be 200m tall, 80m wide at top, 250m wide at bottom containing as much as 500,000 tons or more of ore. To enhance the surface area to volume ratio for improved aeration, finger dump having much greater length than the height or width can be used. At Butte, Montana, a finger dump, 800m long, 35m high, and 200m wide was constructed [26].

The permeability of the fragmented rock materials in the dump is important for efficient percolation through the bed cross-section. Solution irrigation management is generally similar to both dumps and heaps. Shallow ponds covering the upper surfaces can be used. At the Silver Bell mines, Arizona, square ponds with 18m 0.6m dimensions were used. The leach solutions can also be sprayed on upper surfaces using sprinklers or perforated pipes. At Anaconda Butte mine in Montana, liquor injection method providing vertical holes on centers and interactions from the dump surface was practiced [26]. Adequate aeration can be provided by compressed air passed under pressure though PVC lines. Temperature within dumps needs to be ascertained. Microflora inhabiting dumps participate in the mineral dissolution and exhibit varying activities with temperature changes. While the ambient temperatures may be very low (5C), the temperatures within deep regions of the dumps and in solutions could be higher. For example, in certain regions of the dump at Bingham Canyon, temperatures as high as 60C80C have been measured. Thermophilic organisms are favored within dumps. The microflora of commercial dumps is often complex and heterogeneous promoting of synergistic growth and activity among aerobes, anaerobes, mesophiles, and thermophiles [26].

Vlaikov vrah mine in Bulgaria contained about 30 million tons of waste low-grade copper sulfide and mixed ores. Several ore dumps exist at the mine sites. The largest dump was formed on a moderately steep hill without ground preparation during 196079. From the open cast mines, the ore materials were dumped to the top through trucks, as a series of thin sloping layers and contained all sizes (12m diameter boulders to 500mm and fines). Average copper content was 0.10%0.15%, in the form of chalcopyrite, covellite, and chalcocite along with pyrite. Leaching was started in 1972 using solution containing acidophilic chemolithotrophs in sulfuric acid pumped to the top. Effluents from the bottom were sent to for copper cementation with iron. Spent solutions with make-up water were reintroduced to the top of the dump by spraying and flooding using sprinklers and ponds. Rest periods in between were employed. In the dump sections containing chalcopyrite, the annual recovery was as low as 3%. Cumulative copper extraction after 1012 years was less than 20%. A test dump containing 100,000 tons of mixed ore with 0.15% Cu was leached for 10 years and problems analyzed with respect to percolation of solution, formation of clayey layers, and stagnated zones. Analysis of the microflora revealed the presence of acidophilic chemolithotrophs in the dump and recirculation solutions [27].

Decreasing grades of near-surface mineral deposits have resulted in increase in mining costs due to the necessity of processing and transport of large volumes of waste rocky materials per unit of recovered products. Both open cast and underground mining and extraction of valuable metals from lean-grade ore deposits have become economically and technically unviable under the circumstances. ISL has therefore received renewed attention as a cost-effective mining and metal extraction technology. In situ mining is defined as the removal of valuable metal components of a mineral deposit without physical extraction of the rock. Minerals are leached from rocks through permeation of lixiviant solutions and pumped back to the surface [28].

Uranium recovery from permeable (porous) sand stone deposits has been estimated in the range of 60%90%. Comparatively, copper recovery from porphyry deposits using ISL is on a much lower scale. San Manuel in situ mining in Arizona reported copper recoveries in the range of 50%60% over a period of 5 years. Copper was recovered through this method at ASARCOs Silver Bell Copper mine in Arizona from fragmented ores. Even recoveries as small as 20%25% is believed to be economical. ISL accounting for over 40% of world uranium production was developed in the United States, Canada, and the Soviet Union during the early 1960s. This method for uranium extraction is effective at depths of 200feet or more, even for low-grade deposits (0.1% U3O8). In the 1960s, uranium extraction by bioleaching was carried out by spraying stope walls with acid mine drainage solutions. In situ irrigation of fractured underground ore deposits was also carried out. ISL recovery for copper has been limited to a few operations in the United States. Previously mined sites (as different from virgin ore deposits) had been used for in situ copper recovery at ASARCOs Silver Bell mine and BHPS San Manuel Copper mine, both in Arizona. Magma Copper carried out demonstration of ISL leaching for copper during the 1990s. In situ bioleaching of copper from sulfide deposits (pyrite, pyrrhotite, and chalcopyrite) was piloted at San Valentino di Predoi mine in Italy [28].

ISL has been used in combination with open pit or underground excavation and can facilitate low-cost recovery of copper from untapped low-grade ores. Areas such as underground workings and pits can be targeted for copper extraction. It could be a viable option especially in regions below the water table in which the mineralization is easily accessible and having natural permeability. Permeability and porosity can also be enhanced wherever necessary through selective fracturing. Stope bioleaching and underground in situ uranium leaching are illustrated with examples in Chapter 6, Bioleaching of Copper and Uranium. Diagrammatic representations of ISL of fractured underground deposit and that of old mine workings are shown in Figs. 5.4 and 5.5.

ISL is based on several interdisciplinary disciplines such as geology, geomicrobiology, solution chemistry, process chemical engineering, rock mechanics, and metallurgical chemistry. Appropriate lixiviant solutions are pumped through permeable rock media in such a manner that desirable mineral components are solubilized. The pregnant solution is then collected and pumped to the surface and treated for metal recovery.

Leaching of metals can be done in underground stopes, promoted by bacterial oxidation processes. Permeability of the ore matrix is an essential criterion. Newer methods of fracturing the rocks through blasting would facilitate lixiviant permeation through the ore body. The following procedural aspects for ISL need to be considered for process optimization.

Rubblization and solution wetting: Different rock fracturing methods to increase permeability. Fracture direction and dimensions need be controlled. For uniform mineral leaching, proper passage of lixiviant solution through mineral-enriched zones of contact needs to be ensured. Solution flow patterns are dictated by physical nature of fractures. Uniformly distributed and interconnected fractures become essential to ensure effective mineralsolution contacts.

Geological and topographical features relevant to in situ mining include location, size, and form as well as mineralogical compositions and lithology of the ore and gangue. Besides, the rock mechanical properties of the host rock and ore minerals are also important. The location is of practical significance as the leach solutions usually circulate in a downward direction and collect in the deepest accessible regions, and need to be pumped to surface. Increasing depths leads to enhanced pumping costs. For uniform contact with leach solutions, the ore body needs to be regular and compact. Veined ore bodies with extended strikes and depths may require multiple solution injection points. Mineralogical characteristics of the ore and gangue constituents will determine dissolution rates and choice of lixiviants [26].

Many of the commercial in situ bioleaching trials involved the utilization of ore bodies which were initially exploited by conventional mining and subsequently considered depleted. For example, at Derg tyarskii mines in the former Soviet Union, leach solutions were prepared in microbial regeneration tanks and pumped to injection wells extending to mined-out stopes, drifts, and adits. Pregnant solutions were pumped up to the surface for metal recovery. Examples of ISL of virgin ore bodies are also known [26].

In the northeastern part of the Netherlands and northwestern Germany many salt deposits are present, both salt beds at great depths and a number of salt domes reaching to a few hundred meters below the surface. In 1972 work was initiated to study the use of one of these salt domes as a waste disposal site. First the work was directed towards a cavity, to be formed by solution mining, as a facility for disposal of low and medium level wastes. Later also the future construction of a disposal mine for solidified reprocessing waste was added to the programme. At present a general safety evaluation of the disposal of high-level waste in a salt dome is in progress. The fact that in a geologic sense a salt dome is not a completely stable formation is extensively taken into account therein.

In the meantime a number of salt domes have been identified as potential sites. A selection is now being made also with regard to the above ground situations. This study will be followed by exploratory drilling to establish the precise data on the salt and the overlaying sediments for the selected salt dome. Using soil samples from other exploratory drillings chemical work on soil retention of radionuclides was also started.

solution mining

solution mining

Solution mining entails the injection of brine solutions into underground potash-bearing or other salt seams. The solution dissolves soluble potash-bearing minerals from the seam, and the pregnant potash-bearing solution is then recovered to the surface for processing. Solution mining techniques, focused on caverns in halite, are discussed in detail in Chapter 13, Warren (2016). Solution mining can substitute for conventional shaft mining in some potash deposits at depths of more than 1,100m, which is the current limit for conventional potash mining. It is not an all-encompassing mining alternative to be used whenever potash zones are too deep or too variable for conventional mining methods. Currently, there are six active and a number of planned solution mining operations, focused specifically on potash recovery (Warren, 2016). Thickness, mineralogy, and structure/ore-continuity, as well as other technical considerations of the mining operation, must be evaluated to determine the suitability of solution mining.

Intrepid potash solution mines potash-rich brine from deformed salt beds in the Paradox Formation at Moab, Utah and then uses solar concentrators to achieve a product appropriate for processing. The Mosaic operation near Moose Jaw, Saskatoon, recovers potash brine by solution mining a sylvinite bed (Belle Plaine Member) 9 to 15 metres thick at a depth of 1,650 m using a patented solution and recovery method. To capture the ore, hot undersaturated brine feed is pumped into the dissolution cavity. Concentrated potash brine is then returned to the surface processing plant, which uses a sequential evaporation-crystallisation process to recover potash and recycle hot NaCl-rich brine to the subsurface for another leach cycle. In the dry steam-driven evaporation stage in the processing plant, moisture is removed, and the recovered brine is brought to saturation point. But halite and sylvite have different temperature responses. Halite is crystallised first by evaporating the recovered brine, and then potash is recovered by cooling the remaining hot, saturated solution.

Today, most single well solution mining operations utilise a modified annular injection method, known as variable point injection, where both the tubing string and the casing string are positioned near the lowermost level of salt to be dissolved. Undercuts of more than 100 m diameter are achieved using a gaseous or liquid roof pad. In captive wells, brine production rates of more than 13 litres/sec have been obtained once the blanket is withdrawn. As solution proceeds both the tubing string and the casing strings are raised clear of the accumulating insolubles (snubbed). This type of well is also capable of achieving planned-cavity shapes suitable for waste storage. An interesting test of the efficiency of both single-well and two-connected-wells solution mining systems targeting a thin bed of sodium borate was described by Taylor (1970). An 8.8-metre thick layer of borate ore, which was 107 metres below the land surface with a 72% ore grade, was solution-mined in a series of tests. At the completion of the tests the cavities were physically mined (entered) and inspected. No roof padding was employed during the tests. Hot water at 102 to 110C was injected as a feed into the 21C formation and a 15 litre/min flow produced an almost saturated borax solution with an exit temperature around 77C. As the test progressed, feed temperature was steadily decreased and the allowable flow rate of the saturated solution steadily increased. On later cavern entry it was found that broad morning glory holes had formed and large amounts of insolubles had accumulated on the cavern floor. Clay and shales from the roof had fallen as intraclasts with a sand and gravel structure. Cavity bottoms were dominated by this material, rather than by fine bottom slimes usually postulated to dominate cavity bottoms. Some slabs of borate remained encased in the pile of insolubles, where they remained buried as unleached blocks.

Expert design of solution wells is for the most part dependent on geological understanding of the salt to be exploited. Required knowledge includes: dip and thickness variations of the target bed; mineralogical composition, homogeneity, insoluble levels and dissolution behaviour of the target salt bed and adjacent salt layers; distribution and mineralogy of intrasalt beds; structural integrity of confining beds. Caverns engineered in salt domes tend to be more reliable and predictable structures than caverns engineered in bedded salts and are more suited to product storage especially if the product is stored under pressure. Compared to dome salt, bedded salt in the vicinity of a solution well tends to be thinner and bound above and below by more permeable formations. Bedded salt is also more likely to enclose layered intrasalt beds with varying levels of solubility and fracture intensity (anhydrite, shale and dolomite intrabeds) and so tends to supply significantly higher quantities of impurities to the cavity floor. The most stable cavern shape for purpose-designed storage resembles a giant carrot or cucumber embedded deep in a mass of salt. This ideal shape is next to impossible in bedded salt, and to continue the vegetable garden analogy, jack-o-lantern pumpkins are a more likely outcome.

In conventional solution mining of potash intervals, all of the halite in the dissolution cavern must be leached along with the potash to keep the face of the solution cavity open and dissolving rapidly. Otherwise, a buildup of salt and insolubles on the active dissolution face cause blinding. Bottom casings are raised (snubbed) periodically to keep above the accumulation of insolubles. In all solution brine operations, including those targeting potash intervals, flow rates are kept low enough to produce a transparent almost saturated brine. Because the targeted potash bed is typically thin with respect to the halite host, well capital and operating costs are comparatively high, but are reported to be still less than conventional potash mining. When potash is recovered from diapiric intervals, the bed inclinations can be steep and thicknesses variable. Differential rates of dissolution can complicate the control of the solution cavern shape and ore bed targeting, and the susceptibility of bed flow back into the cavity is controlled by mineralogy. Relevant published potash solution mining articles and processing patents include; Bach et al. (1985), Day (1967), Dillard et al. (1975) and Schlitt (1982). See Warren 2016, Chapter 13 for more detail.Texas Gulf solution mines potash-rich brine from deformed salt beds in the Paradox Formation at Moab, Utah and then uses solar concentrators to achieve a product appropriate for processing. The IMC Kalium operation near Moose Jaw, Saskatoon, recovers potash brine by solution mining a sylvinite bed (Belle Plain Member) 9 to 15 metres thick at a depth of 1,650 m using a patented solution and recovery method based on different temperature and solutity responses acress halite, sylvite and carnallite (Figure). To capture the ore, hot undersaturated brine feed is pumped into the dissolution cavity. Concentrated potash brine is then returned to the surface processing plant, which uses a sequential evaporation-crystallization process to recover potash and recycle hot NaCl-rich brine to the subsurface for another leach cycle. In the dry steam driven evaporation stage in the processing plant, moisture is removed and the recovered brine is brought to saturation point. But halite and sylvite have different temperature responses (Figure). Halite is crystallized first by evaporating the recovered brine, then potash (a prograde salt) is recovered by cooling the remaining hot, saturated solution.Carnallitite, like trona, shows incongruent solubility so that in beds composed of mixtures of carnallite, sylvite and halite, the sylvite tends to be left behind as a less soluble component that can slow the rate of dissolution (surface blinding; Figure). Furthermore, the solubility of halite, sylvite, and kieserite is very low in strong MgCl2 solutions and this limits exploitation in intervals where these minerals are co-associated.

The NedMag solution mining facility near Veendam in the Nederlands produces magnesium from magnesium chloride brine by solution mining a Zechstein salt diapir, targeting beds that are a mixture of carnallite (KCl.MgCl2.6H2O), bischofite (MgCl2.6H2O) and halite (NaCl), with some sylvite (KCl) and kieserite (MgSO4.H2O). Target intervals at Veenham average 100 metres (combined) thickness at depths, dipping around 20, at depths between 1,400 and 1,800 m (Figure A). About a 100 metres of halite lies above the target magnesium salts and more than 1,400 m occur below (Figure B Fokker, 1995). Beds were accessed by a total of 12 solution wells drilled between 1972 and 1991. Nine of these wells were still operational in 2000 with average brine production per well around 25 m3/h. NedMag has recently excavated one of the deepest solution mining cavities in the world at 2,890 metres. Each year the NedMag plant produces in excess of 150,000 tonnes of high purity synthetic dead-burned magnesia and more than 70,000 tonnes of magnesium chloride in liquid or solid form. A similar solution-mined operation producing MgCl2 brine by targeting bischofite beds is planned for a large deposit near Volgograd in Russia.The mining procedure at Veendam utilizes a backstepping solution cavity method (Figure A ; Fokker, 1995). Cavity extent is limited to 100 m diameter (perhaps now extended to 150 m), and the brine is maintained at the original downhole (lithostatic) pressure. Wells are designed to be plugged and abandoned at full pressure. During production the magnesium salt-rich layers are preferentially dissolved, leaving behind many halite balconies on the cavity walls. Eventually the balconies collapse. This creates considerable insoluble rockfall and mud deposition on the cavity floor, compared to conventional cavities that target homogenous halite. Dealing with this extra volume of collapse debris requires frequent raising of both the injection (to control the cavity diameter) and the withdrawal pipes (to prevent blockages; Figure). Cavern pressures are kept relatively low in the producing caverns (average of 10 MPa or 100 bars) and well below the far field rock stresses. This facilitates salt creep into the cavern, but the lower viscosity of the magnesium salts compared to halite means they are preferentially squeezed like toothpaste into an active solution cavern at a rate far greater than the creep of the adjacent halite (Figureb). Hence, the bischofite beds supply far greater volumes to the dissolution cavern than the adjacent halite beds, with convergence rates contributing 30-40% of the produced MgCl-brine volume. This method has been called squeeze mining and the brine product from squeeze caverns can be very pure. For example, four wells producing brine from squeeze caverns at Veendam are almost saturated with respect to bischofite, rendering a high quality brine product with less than 1% by weight of non-magnesium chloride salts.Although the degree of creep is not well understood,it has been established that halite shows a much lower creep than carnallite, which in turn shows a much lower creep than bischofite (Figure B; Drijkoningen et al., 2012). Although the strain rate depends on differential stress, the strain rates can be estimated very roughly, in order of magnitude, as 1:10:100, respectively. The bischofite will therefore creep towards the caverns, resulting in a gradual thinning of the salt layer. Bischofite will creep due to pressure difference between lithostatic pressure depending on the depth and the pressure applied in the cavern. In the development of cavities it is important to note that squeeze-mining has a different effect than conventional solution mining under lithostatic conditions, because part of the created brine is replaced by solid salt. This enables production of more salt from the same cavern (Drijkoningen et al., 2012). A counter-effect is that squeeze mining leads to a more rapid surface subsidence than conventional lithostatic mining, in which there is no net volume change in the salt layers. The squeeze mining leads to extra deformation of the overburden, which in turn causes extra subsidence of the Earths surface. Dutch regulations now impose a maximum subsidence of the surface of 65 cm for this mine, limiting production in the future. By carefully maintaining the proper MgCl2 concentration in the Veendam cavern brines and monitoring solution flow rates using variably pressurised waters, NedMag has minimised blinding in bischofite beds (Steenge 1979). For successful magnesium chloride recovery, the solution rate, the dissolving surface and the produced brine at Veendam must be maintained at all times at an almost saturated condition. The operations at Veendam are a worldclass example of targeted and monitored solution mining with a set of process technologies specifically designed for the brine product. Historically, high levels of carnallite in some potash beds in the Zechstein have made them a poor choice for a KCl targeted beds in both solution and conventional mining operations. But NedMag has recently begun to use a patented process to produce brines that are also saturated with respect to carnallite from carnallitic beds previously considered subeconomic

smi industrial mechanical evaporators for produced, process and wastewater treatment

smi industrial mechanical evaporators for produced, process and wastewater treatment

SMI produces durable industrial mechanical evaporators designed for a range of environments and operating conditions. Our produced water evaporation equipment and systems can be a low cost addition when considering zero discharge options at your site. We offer complete solutions, from initial site analysis to remote centralized computer control systems. We monitor weather data, then modulate flow at each individual evaporator to maximize efficiency and contain spray drift within the operational area. We specialize in water fracturing and fan atomization technology based evaporators featuring the SMI 420 Evaporator and the PoleCat Evaporator series.

With over 1,000 Evaporators in the field at over 250 customer locations, SMI is the largest mechanical evaporator manufacturer. Our systems are used in a variety of industries including mining, oil and gas, food processing, wood processing, small town waste treatment and power generation.

mining | britannica

mining | britannica

mining, process of extracting useful minerals from the surface of the Earth, including the seas. A mineral, with a few exceptions, is an inorganic substance occurring in nature that has a definite chemical composition and distinctive physical properties or molecular structure. (One organic substance, coal, is often discussed as a mineral as well.) Ore is a metalliferous mineral, or an aggregate of metalliferous minerals and gangue (associated rock of no economic value), that can be mined at a profit. Mineral deposit designates a natural occurrence of a useful mineral, while ore deposit denotes a mineral deposit of sufficient extent and concentration to invite exploitation.

When evaluating mineral deposits, it is extremely important to keep profit in mind. The total quantity of mineral in a given deposit is referred to as the mineral inventory, but only that quantity which can be mined at a profit is termed the ore reserve. As the selling price of the mineral rises or the extraction costs fall, the proportion of the mineral inventory classified as ore increases. Obviously, the opposite is also true, and a mine may cease production because (1) the mineral is exhausted or (2) the prices have dropped or costs risen so much that what was once ore is now only mineral.

Archaeological discoveries indicate that mining was conducted in prehistoric times. Apparently, the first mineral used was flint, which, because of its conchoidal fracturing pattern, could be broken into sharp-edged pieces that were useful as scrapers, knives, and arrowheads. During the Neolithic Period, or New Stone Age (about 80002000 bce), shafts up to 100 metres (330 feet) deep were sunk in soft chalk deposits in France and Britain in order to extract the flint pebbles found there. Other minerals, such as red ochre and the copper mineral malachite, were used as pigments. The oldest known underground mine in the world was sunk more than 40,000 years ago at Bomvu Ridge in the Ngwenya mountains, Swaziland, to mine ochre used in burial ceremonies and as body colouring.

Gold was one of the first metals utilized, being mined from streambeds of sand and gravel where it occurred as a pure metal because of its chemical stability. Although chemically less stable, copper occurs in native form and was probably the second metal discovered and used. Silver was also found in a pure state and at one time was valued more highly than gold.

According to historians, the Egyptians were mining copper on the Sinai Peninsula as long ago as 3000 bce, although some bronze (copper alloyed with tin) is dated as early as 3700 bce. Iron is dated as early as 2800 bce; Egyptian records of iron ore smelting date from 1300 bce. Found in the ancient ruins of Troy, lead was produced as early as 2500 bce.

One of the earliest evidences of building with quarried stone was the construction (2600 bce) of the great pyramids in Egypt, the largest of which (Khufu) is 236 metres (775 feet) along the base sides and contains approximately 2.3 million blocks of two types of limestone and red granite. The limestone is believed to have been quarried from across the Nile. Blocks weighing as much as 15,000 kg (33,000 pounds) were transported long distances and elevated into place, and they show precise cutting that resulted in fine-fitting masonry.

One of the most complete early treatments of mining methods in Europe is by the German scholar Georgius Agricola in his De re metallica (1556). He describes detailed methods of driving shafts and tunnels. Soft ore and rock were laboriously mined with a pick and harder ore with a pick and hammer, wedges, or heat (fire setting). Fire setting involved piling a heap of logs at the rock face and burning them. The heat weakened or fractured the rock because of thermal expansion or other processes, depending on the type of rock and ore. Crude ventilation and pumping systems were utilized where necessary. Hoisting up shafts and inclines was done with a windlass; haulage was in trucks and wheelbarrows. Timber support systems were employed in tunnels.

Great progress in mining was made when the secret of black powder reached the West, probably from China in the late Middle Ages. This was replaced as an explosive in the mid-19th century with dynamite, and since 1956 both ammonium nitrate fuel-blasting agents and slurries (mixtures of water, fuels, and oxidizers) have come into extensive use. A steel drill with a wedge point and a hammer were first used to drill holes for placement of explosives, which were then loaded into the holes and detonated to break the rock. Experience showed that proper placement of holes and firing order are important in obtaining maximum rock breakage in mines.

The invention of mechanical drills powered by compressed air (pneumatic hammers) increased markedly the capability to mine hard rock, decreasing the cost and time for excavation severalfold. It is reported that the Englishman Richard Trevithick invented a rotary steam-driven drill in 1813. Mechanical piston drills utilizing attached bits on drill rods and moving up and down like a piston in a cylinder date from 1843. In Germany in 1853 a drill that resembled modern air drills was invented. Piston drills were superseded by hammer drills run by compressed air, and their performance improved with better design and the availability of quality steel.

Developments in drilling were accompanied by improvements in loading methods, from handloading with shovels to various types of mechanical loaders. Haulage likewise evolved from human and animal portage to mine cars drawn by electric locomotives and conveyers and to rubber-tired vehicles of large capacity. Similar developments took place in surface mining, increasing the volume of production and lowering the cost of metallic and nonmetallic products drastically. Large stripping machines with excavating wheels used in surface coal mining are employed in other types of open-pit mines.

Water inflow was a very important problem in underground mining until James Watt invented the steam engine in the 18th century. After that, steam-driven pumps could be used to remove water from the deep mines of the day. Early lighting systems were of the open-flame type, consisting of candles or oil-wick lamps. In the latter type, coal oil, whale oil, or kerosene was burned. Beginning in the 1890s, flammable acetylene gas was generated by adding water to calcium carbide in the base of a lamp and then released through a jet in the centre of a bright metal reflector. A flint sparker made these so-called carbide lamps easy to light. In the 1930s battery-powered cap lamps began entering mines, and since then various improvements have been made in light intensity, battery life, and weight.

Although a great deal of mythic lore and romance has accumulated around miners and mining, in modern mining it is machines that provide the strength and trained miners who provide the brains needed to prevail in this highly competitive industry. Technology has developed to the point where gold is now mined underground at depths of 4,000 metres (about 13,100 feet), and the deepest surface mines have been excavated to more than 700 metres (about 2,300 feet).

salt mining | howstuffworks

salt mining | howstuffworks

In 2006, more than 200 million tons of salt were produced in the world. China is the largest producer, with 48 million tons, followed closely by the United States, with 46 million tons [source: Salt Institute]. Salt is generally produced one of three ways: deep-shaft mining, solution mining or solar evaporation.

Deep-shaft mining is much like mining for any other mineral. Typically, the salt exists as deposits in ancient underground seabeds, which became buried through tectonic changes over thousands of years. Many salt mines use the "room and pillar" system of mining. Shafts are sunk down to the floor of the mine, and rooms are carefully constructed by drilling, cutting and blasting between the shafts, creating a checkerboard pattern. After the salt is removed and crushed, a conveyor belt hauls it to the surface. Most salt produced this way is used as rock salt.

In solution mining, wells are erected over salt beds or domes (deposits of salt forced up out of the earth by tectonic pressure) and water is injected to dissolve the salt. Then the salt solution, or brine, is pumped out and taken to a plant for evaporation. At the plant, the brine is treated to remove minerals and pumped into vacuum pans, sealed containers in which the brine is boiled and then evaporated until the salt is left behind. Then it is dried and refined. Depending on the type of salt it will be, iodine and an anti-clumping agent are added to the salt. Most table salt is produced this way.

When solution mines are located near chemical plants, they are called brine wells, and the salt is used for chemical production. After the salt is removed from a salt mine, the empty room often stores other substances, like natural gas or industrial wastes.

Salt is harvested through solar evaporation from seawater or salt lakes. Wind and the sun evaporate the water from shallow pools, leaving the salt behind. It is usually harvested once a year when the salt reaches a specific thickness. After harvest, the salt is washed, drained, cleaned and refined. This is the purest way to harvest salt, often resulting in nearly 100 percent sodium chloride. Only areas with low annual rainfall and high evaporation rates -- Mediterranean countries and Australia, for example -- can have successful solar evaporation plants. Usually machines perform this harvest, but in some areas it is still done by hand.

mining evaporation equipment & water evaporation solutions | rwi, inc

mining evaporation equipment & water evaporation solutions | rwi, inc

RWI Enhanced Evaporation provides mining evaporation equipment with our latest patent-pending technology and innovative engineering. We quicklyreduce large volumes of production water while mitigating any environmental liability.

The 2.0 series evaporators are an excellent alternative to treatments such as chemical dosing or reverse osmosis.Our water evaporation mining solutions technologyis suitable for various applications including:

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