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proline gold mining and prospecting equipment/parts and accessories

proline gold mining and prospecting equipment/parts and accessories

For your convenience, wecarry a wide assortment of Parts & Accessories for your Proline products. We are committed to making your online experience enjoyable and it's our job to make sure you find what you are looking for fast. We back this commitment by offering our help via e-mail or phone whenever you need it! So, if you don't see it, please ask! Select from the categories to your left to narrow your selection in this large section.

Proline offers one of the most comprehensive line of pumps in the small dredge industry. These are high performance centrifugal pumps designed specifically for operating our dredges and dual-purpose machines. Each pump is cast in the US from premium quality A356 aluminum, then heat treated to a "T-6" hardness for years of service. Every component is then machined on computer controlled equipment to ensure the exact tolerances required for optimum performance. We use 5, 6, and 7 vane "aggressive bite" impellers with large intake throats to provide high volume with greater working pressure than similar pumps on the market. They are hand-assembled using US made seals, heavy duty reusable gaskets, and grade 8 hardware. The quality and performance of these units, when coupled with our efficient jetting systems, offers outstanding dredge vacuum with very little service required.

PCA10 oilless air compressors are built to withstand the most rugged operating conditions with corrosion-resistant materials used for critical internal parts. Ring design provides consistent flows throughout the service life of the unit.

The T-80 is a medium-duty oilless diaphragm compressor with pressure relief valve. It connects easily to dredge motor to supply hookah breathing system.. The T80 compressors are recommended for shallow diving conditions including dredging. Factory recommended RPM is 1800 5/8" keyway shaft. Produces 1.8 CFM at 45 PSI. Pulley is not included but offered separately below.

Our foot valves are made of steel and aluminum and are designed to provide years of trouble-free service. Their low restriction design is ideal for maintaining maximum pump performance. Unlike plastic foot valves, they do not float to the surface. Best of all, they can be easily disassembled and rebuilt if necessary.

No one makes power jets like Proline. Rather than using a steel casting, we use a more efficient machine formed eductor. The result is a lighter power jet with better vacuum and easier priming. These power jets are popular with those building their own dredges or who simply wish to improve performance on dredges they already own.

Our new line of suction nozzles set the standard for efficiency and durability. We start wih thicker tubing, mandrel-bent to minimize distortion. Rather than swedging the inlets of the nozzles to control rock size, we equip them with hardened steel wear rings, just like our swivel tips. Our unique, machined steel venturi orifice provides better vacuum and greater lifting capability. Every nozzle is tig welded in a fixture for strength and accuracy. The very best you can buy.

Proline swivel tips set the standard for design and construction. The tip smoothly rotates 360 degrees and is equipped with a large handle. Our unique swivel seal is less prone to seizing from sand than other designs. The 3 and larger tips include a high carbon steel wear ring which is spaced out from the nozzle body to increase dredge capacity and to make it easier to remove large rocks from the tip.

Spark arrestors play a critical role in the prevention ofwildland fireand ignition ofexplosive atmospheres. As such, their use is required by law in many jurisdictions worldwide. These spark arrestors are US Forestry approved and can be used with 2.5hp - 11hp Honda engines.

We have hoses for most any application. We stock suction hoses for dredging, pressure hoses for powering dredges, and layflat hoses for highbanking use. We offer many sizes and styles to choose from and maintain a good supply of various size hose clamps and couplings. Contact us if you dont see what you need!

reserve replacement - a challenge for the gold mining industry! | gold eagle

reserve replacement - a challenge for the gold mining industry! | gold eagle

For years I've kept wondering how the major mining companies will be able to keep up their rate of production, never mind expanding it. Well, some did it by acquisition only - and it was a sad day for me when the over 100 year's old historical flagship company of US gold mining, HOMESTAKE MINING, was taken over by modern day buccaneers for, what I feel, was cents to the dollar. Of course, we all appreciate that Homestake had hit a low of $3.50 and appreciated more than 100% before it was sadly taken out by Barrick , a company I would suggest has been a politically correct entity, though still, or better because of it - a predator, or some would even call it a vulture fund.

Take-overs don't change the overall equation of adding to mine-able reserves, even if they boost the production of the acquiring company for a little while. On the other hand these increased reserves were hugely offset by "high-grading" existing reserves in the era of ultra depressed gold prices. - thus rendering large portions of former reserves unmineable at any future price and so reducing mine-life substantially, and in some cases lethally.

At the same time, exploration and development has been slashed to practically zero. Since 1996 almost all new projects have been put on hold as the price of gold tanked because of the announcements that Central Banks intended to sell most of their gold reserves - a redundant, non-interest-carrying, barbaric relic, as it was already termed by the likes of John Maynard Keynes, the "godfather" of deficit spending more than half century ago. This development now seems to begin taking its toll on the fiat monetary system, which is based on the US-dollar as reserve standard. And not only for the gold miners, no, that only was a side show!

The reality is that the fiat monetary system was construed to buy additional time for the global reserve currency, the fiat dollar. The quantity of dollars was already self indulgently over-inflated then. In recent years the flooding of the currency markets became exponential and as Bill Buckler of "The Privateer" has termed it, led to a "Potemkin" economy, where only the ever increasing creation of paper dollars out of thin air may keep up the delusion of GDP growth.

To return to the subject of gold reserve replacement in an environment where some major producers seem to have obligated years of future production at fixed lower prices. These allow accounting convenience, but limit potential value increase; You really can't sell your product twice. It also follows that the intelligence of financial markets prices these "obligated" producers accordingly. This is evident from the valuations of Barrick, Placer Dome and most Australian producers and others of the same ilk. "Remember the Ashanti" may become the war cry for gold bugs, akin to "remember The Alamo" for old timers in Texas. Declared non-hedgers like Royal Gold, Gold Corp., and even Newmont, the declared anti-hedgers instead are showing strong advances in valuation.

My aim here is to initiate discussions on gold projects in North America, which may eventually become potential sources of reserve replacement for majors. Some may even find it more rewarding to go it alone, as Goldcorp. has proven this as it has been a valuation bonanza.

The first place I want to look at is Nevada. The state is producing about 2/3 of the US's gold, which is roughly 250 annual tons. Not bad at all for the former Silver State - though silver is still accompanying gold production.

The major strikes in the early 80's were along the Carlin, Battle Mountain, and Getchell trends. All located in North-Central Nevada. As Barrick, Newmont and Placer Dome seem to control most of it, the idea is to identify potentially prolific areas between these vast tracts of geography. After all, the controlling companies were not exempt from high-grading and so destroying some of their potential bonanzas in recent years. And to my knowledge, with the exception of Placer Dome delineating Cortez Hills and maybe ET-Blue, no other meaningful exploration has been conducted since than by the 3 biggies.

My initial thoughts are directed towards the Sleeper Mine and its adjoining areas. Amax, the previous owner, never explored any adjacent targets, nor depths over 500 ft. The original Sleeper Mine was developed and brought to production by Amax Gold, since taken over by Kinross Gold. The Sleeper open pit mine was among Nevada's most high grade gold deposits. It produced about 1.7 million ounces an average cash costs of 158 dollars per ounce of gold between 1986 and 1996.

X-Cal Resources Ltd., a TSE listed gold exploration company, holds three properties located in some of North America's most prolific geological settings known to have produced economical gold deposits. They have assembled a 30 square mile (20.000 acre) property at and around the Sleeper Mine. The property is jointly owned by Kinross Gold and X-Cal Resources each holding a 50% stake, except for 5.000 acres where X-Cal holds a 100% interest. Furthermore X-Cal has the option to buy out the Kinross stake until the end of 2003, which essentially means to take over the reclamation bonding from Kinross. In the case of exercising the option Kinross would still be a substantial shareholder of about 13%.

X-Cal has undertaken an extensive program of geophysics, geochemistry, satellite imagery, and soil sampling as well as 3-D modelling and a thorough review of all data from Amax Gold. Past and recent drilling programs seem to verify the potential of multiple Sleeper-like and other major Nevada-type deposits. Gold deposits throughout Nevada occur as clusters. Identified drilling targets in the Sleeper area may host up to 35 or more of these potential deposits.

Some top notch people advising X-Cal are Keith Blair and Win Rowe. Both have expediently furthered the coompany's exploration and development process and added hugely to the geological interpretation of property, by organizing and building the vast database. Over the past year two top Nevada geological guns were enthused to accept the call to participate in the ongoing exploration program - please read their endorsements on the property following below. Both Ken Snyder (K.Snyder Mine, Midas) and Larry Kornze (Gold Strike, Betze et al) have multi million oz's to their credit in Nevada. They have also kindly given permission to publish their endorsement on a broader scale. Larry Kornze is essentially saying that the property has enormous potential of reserve replacement, being both ideally located in terms of its geological promise as well as being in the epicentre of the major mining facilities of the area. His endorsement for the property was already published on The Metropole Caf a few weeks back. I will therefore quote only Ken Snyder's letter to X-Cal's management in its entirety:

After several years of having a favorable impression toward the general exploration potential of the Sleeper Mine district (but no direct involvement), I was pleased when you asked me to become acquainted with the specific technical data on the mine area. I must state that after six months of this more in-depth study of the data, I am even more excited and confident about the future of mining in the district.

In the immediate mine area, there are numerous high-priority target areas remaining to be evaluated. Having studied the MapInfo tables and maps, it seems that the entire area remains largely unexplored at depths greater than 500 feet. Judging by the few deeper drill holes that are available, high gold grades certainly exist at depth in most of the areas tested. The reason for this lack of exploration effort at depth in the past caused me some wonder; presumably it was due to a concern over water volumes - but we certainly haven=t seen any water volumes in the deep X-CAL drilling to justify not exploring.

The area from the Wood Pit to the south and west, where drilling has been focused this summer, still remains open at depth and laterally in all directions. Multiple bonanza veins are likely to occur throughout that area.

The Aready [email protected] area to the east and southeast of the Sleeper Pit is an attractive target with essentially no drilling greater than 500 feet deep. The best geochemical anomaly of the mine area bounds this target on the east side and probably represents a zone of significant hydrothermal solution influx along the volcanic/metasediment stratigraphic interface. A number of the shallow old [email protected] holes in this zone encountered strongly anomalous gold values. Future holes in that area should extend to the volcanic/metasediment interface (I am suggesting a modified Hishikari model setting here).

The west side of the Sleeper Pit is also an attractive target. The northwest-trending zone which piqued Placer=s interest in the area still remains to be tested. The potential dimensions of that mineralization is essentially unrestricted.

The northern end of the Sleeper Pit remains a very attractive target although exploration in that area is somewhat hampered by the old leach pads. This is a problem which will be resolved with time and will ultimately become a very extensive area of potential for multiple bonanza veins trending north-south, northwest, and northeasterly. The potential extent of the zone in these directions appears to be totally unrestricted.

The broader district-scale exploration potential remains as attractive as ever. While district-scale potential has been relegated to a lower priority for the time-being, there are several areas having exceptional potential for the future.

The pediment southeast of the mine area (south of X-CAL=s AArea 1" target) has long been my personal favorite because of my interpretation of regional structure. As near the Sleeper Mine itself, the highest rock chip geochemistry of the district occurs at the volcanic/metasediment interface immediately east of the pediment (another zone of strong hydrothermal solution influx perhaps). Unfortunately, there is currently has no available geophysical coverage in that area. Soil sampling of that pediment would probably not be productive because of the thickness of wind-transported sands. Therefore, geophysics followed by drilling will probably be required to explore this target. The current detailed geological mapping program in this area will be extremely valuable.

The entire pediment area north of the Sleeper Mine is an attractive area for future exploration. Again, there are very few data at present other than surface observations; the proper volcanic host rocks crop out in the area but there are very few rock samples and fewer shallow drill holes from past exploration efforts. This area, from the outcropping metasediments toward the west onto the pediment is virtually an unexplored area. This is surprising since it is essentially adjacent to such a significant mine.

The pediment westward from the Sleeper Mine is an attractive target area (ABedrock [email protected] area and westward). Geophysical data indicates abundant potential for the existence of ore-conduit structures. In the past this area was hampered by thicker overburden and the fear of high in-hole water volumes. Problems associated with drilling through the overburden have been largely resolved and water problems have been discounted.

The X-CAL exploration effort appears to be proceeding in a logical and systematic manner. Of the currently active district exploration plays in Nevada, the Sleeper Mine district is the one having the highest potential for major success. In Nevada, major exploration programs are underway, or soon to be underway, at Aurora, Goldfield, Midway, Tokop, Montello, Robinson, Silver Cloud and McDermitt, as well as Sleeper. Sleeper is personally rated higher than the others for potential for both high grade and high tonnage. My recommendation is to continue exploring on the same course.

Another potential source of a major reserve replacement play is Coral Gold Corp., a VSE listed explorer with a 14.000 acre Tenabo Property on the Battle Mountain Trend. The property was put together under the guardianship of the famed geologist Dr. Ralph Roberts. Dr. Roberts worked for the USGS since the early 50's and has probably foreseen the new Nevada gold rush early on. After all, about 20 years ago he predicted that over the term of a generation or two, this North-Central section of Nevada will produce more gold than South Africa today. Well, it seems we're getting close to these numbers.

The history of the property, at least since Coral controls it is quite fascinating - as is its earlier history. Dr. Roberts has just published a book about the area, where Tenabo almost fills a chapter. Since Coral Gold got involved the board decided to develop the first delineated gold deposits into production, which started at about late 1987. Of course the gold price still hovered above $ 500/oz and the future seemed golden. The ensuing collapse of the POG has led to closing the production shop and the search for JV-partner, which soon was found in Amax Gold (editor's note: this company seems to haunt my Nevada experiences). Coincidentally, the VP-exploration of Amax Gold at that stage was a very able geologist, Bob Barker, who just happens to have accepted the same position with Coral about a year ago. You can't have a more knowledgeable guy for analyzing the vast existing data base, as well as delineating targets for major drilling programs.

These are now underway, on both the Norma Sass Claims as well as the 39A Zone within the core property. This zone is actually under-explored, even as former drilling came up with 150 to 250 high grade gold intersections, Amax Gold at that stage preferred to limit their commitment to the quick and easy. Back in 1995 they came up with a reserve of about 500.000 ounces of gold in the "Porphyry Zone", an attempt to earn their interest. Unfortunately half of these reserves was fractional ore and not mine-able with existing production means. A fierce battle evolved at their Cyprus, Amax headquarters, dubbed "Taj Mahal" by Coral's CEO, Lou Wolfin. As I've been the other "witness" from the Coral side, please remind me to tell the story of the negotiations at another time.

Anyway, some time later Amax Gold relinquished the property and Coral went its own way again. Suddenly, in the period of a rising gold price from 1993 to 1995 Coral found itself in the limelight again. Placer Dome, or better the Cortez JV has hit the famed bonanza of the "Pipeline Deposit" right next door to Coral's property. Negotiations began - though with a plethora of companies - and of course Placer Dome was a major contender. I still believe Coral would have made it to the finishing line at that stage - after all the share price went from cents to 6.40 dollars, OK, in Canadian Dollars - if the management of the POG had not set in at the time in earnest.

Soon after Placer offered a JV on the property. The extensive and deep drilling program Placer has commenced along the Pipeline Fault corridor did in reality prove up all the expected 'contact zones'. And that was that. Followed by a new manager of the Cortez JV, Coral managed to get more active by reclaiming the core property, though still retaining a carried to production interest of 39% in the now called secluded claims (see maps on the website).

So here's another great play in Nevada's epicenter of potential elephant size. The company's website, www.coralgold.com, host's a lot of great information and several mining analysts have recently endorsed the property as one of the exceptional plays on the Battle Mountain Trend.

This essay was written towards the intent of igniting discussions as to where major producers will start to look in their plight to find new reserves. More gold exploration properties in North America will be highlighted by intended future essays.

alternatives to mercury use in small-scale gold mining - mining zimbabwe

alternatives to mercury use in small-scale gold mining - mining zimbabwe

In Zimbabwe elemental mercury is used in artisanal and small-scale gold mining. Mercury is mixed with gold-containing materials, resulting in the formation of the mercury-gold amalgam which is then heated, vaporizing the mercury to obtain the gold.

This process is very dangerous and can lead to significant mercury exposure with serious environmental and health risks. Minamata Convention on Mercury, aims to reduce mercury pollution, particularly from the artisanal and small-scale gold mining sector. The convention calls for parties to reduce, and where feasible eliminate mercury use within the gold mining sector. Traditionally, the use of mercury is one of the most accepted methods of recovering gold. In view of the dangers associated with mercury, there is need to explore alternatives which are safe and economically viable. Mercury-free techniques are safer for miners, their families, local communities and the nation at large. They may also help miners market their gold at higher prices if they bring the concept of green gold. Below are some of the techniques that can be embraced.

Concentration methods thrive on increasing the amount of gold in ore or sediment, by selectively removing lighter materials (gangue). If employed effectively, concentration methods can eliminate or greatly reduce the quantity of mercury in gold recovery.

Prior to concentration, ore must be crushed or milled to liberate gold particles from rock and to increase the surface area. Concentration works best when particle size of the milled material or sediment is relatively consistent, so that most particles are of similar size. The use of screens or sieves can be employed to get a consistent particle size. Once the gold-containing material has the appropriate particle size, one (or several) of the methods described below can be employed to concentrate gold bearing material:

Most concentration methods rely on the high density of gold relative to other minerals in ore or alluvium mixture. These are referred to as gravity methods. Magnetic or chemical properties can also be exploited to enhance concentration.

Due to spatial and temporal differences as well as the uniqueness in mining operations concentration methods must be selected carefully. Factors such as the type of ore or sediment, other minerals present, gold particle size, and the availability of water and electricity should be considered when selecting a particular method.

The panning process uses water to separate heavy gold particles from lighter ones within a medium sized pan. In this process ore thought to contain gold is placed in a wide, curved pan along with water. The miner moves the pan in a series of circular motions designed to remove lighter sediments. The high density of gold allows it to settle on the bottom of the pan as lighter material is removed along with water. The process is repeated for some time until gold is exposed on the bottom of the pan for the miner to recover.

Panning is effective when gold is relatively coarse and well liberated. All factors being constant, panning can produce high grade concentrates or even liberated gold. Then miners can employ gold recovery methods such as direct smelting (described below), although many panning operations lead to directly recoverable gold. Panning is a low cost technology of gravity concentration that requires time and skill to be effective. One of the major drawbacks to panning is that miners must pan small amounts of concentrate. Therefore, panning is often done after other methods of gravity concentration such as sluicing have completed.

Sluices use water to wash ore or alluvium down a series of angled platforms. As water washes sediment down a sluice, gold particles tend to sink and are captured by material covering the bottom of the sluice, often carpets. Sluices are usually inclined at 5 to 15 degree angle. As moving water travels down a sluice, it generates greater force and keeps gold particles from sinking easily. For this reason most gold is captured at the beginning of the sluice. Carpets or other capturing devices on the bottom of sluices can be removed and washed in a bucket to remove the captured gold.

The design of a sluice can lead to higher gold recovery if the force of the water traveling through the sluice is greatly decreased. Also a series of rifles can contribute towards the management of flow to improve gold recovery. The use of a zigzag sluice can also achieve the same by creating a drop between the first and second platform that disrupts the velocity of the water as it moves down the sluice. Another way of improving the zig-zag sluice is to have a combination of two sluice surfaces. The first is tilted at a steeper angle then the second, decreasing the velocity of the water as it hits the second sluice, increasing gold recovery. Water supply is a prerequisite to have a functioning sluice operation. This can be done with piping, drums, buckets, or natural flowing water bodies. A constant flow will be better than a bucket-driven flow. Sluices are good at concentrating large amounts of ore and sediment in a relatively short time but often do not yield concentrates with high amounts of gold. The resulting concentrate must usually undergo further methods of concentration, such as panning.

Shaking tables are elevated tables tilted to one side with raised ridges running horizontally down their length. Crushed ore or sediment feed and water are released at one end of the table. The water washes the crushed ore down the table. As the material is washed down the table, specialized grooves trap gold and direct it to collection points on the side of the table as lighter minerals are washed away. Concurrently, the table is continually shaken by a motor to agitate the material and aid in the separation of gold.

Shaking tables are effective and can concentrate large amounts of ore at a time, considering high grade concentrates and liberated gold, but they are also relatively expensive and require some experience to operate.

The term spiral concentrator refers to specialized pans tilted on an angle with spiralled grooves. The spiral grooves in the pan lead toward the centre where a hole is connected to a container to catch material.

The pan is rotted continually using a pan as concentrate is fed onto the pan by an operator. In most designs a pipe extending horizontally across the pan sprays water along the surface of the pan as the concentrator spins. The water washes lighter particles down the spiral concentrator into a bucket while denser particles, including gold, are carried by the spiral grooves toward the hole in the centre of the concentrator. The process is repeated several times until the operator is left with a high grade concentrate, and often liberated gold.

Vortex concentrators makes use of a rotating flow of water to separate lighter materials from a concentrate and remove them via a raised drain hole. A vortex concentrator is a circular tub with water input on the side of the tub and a raised drain in the centre. The said circular tub is filled with water until it reaches the level of the drain hole. The concentrate is then added in a thin layer around the bottom of the bowl. Following this, water is then pumped into the side input, creating a rotating vortex of water that drains in the centre. The created vortex pulls lighter material up from the bottom of the bowl and out through the drain hole. Gold because of its high density remains on the bottom of the tub for collection. The methods requires expertise in that there is need to monitor the amount of water flow going into the tub. If it is too great the velocity of the water will carry gold particles out of bowl and this will lead to losses of gold.

By definition, a centrifuge is a vessel that rotates about a central point. Its wide application has been related to the separation of materials in a mixture by density. In a bid to apply the principle to gold processing, concentrate is fed into the centrifuge through an inlet pipe at the top of the centrifuge in a slurry of around 60-75% water and 40-35% solids. The fed material collects in a vessel in the centre of the machine where high speed rotation creates a force that moves the material up the sides of the vessels walls. As the materials are pushed up the sides of the bowls wall, denser material like gold is caught in ridges while lighter material is ejected from the centrifuge.

The use of magnets can be employed to remove magnetic minerals such as magnetite from the concentrate. Magnets can be used after and/or in conjunction with other methods of concentration. One technique for extracting magnetic minerals is to place handheld magnets on the bottom of a pan containing dried concentrate to separate metallic from non-metallic material. It is critical to take due care to avoid losing gold particles during the separation. The use of a piece of paper so that the minerals attracted to the surface of the paper can be easily removed.

The flotation process is usually used by large scale miners but can also be adopted in small scale operations. The process is best for processing complex ore types, especially ores that are difficult to process using gravity methods. When doing flotation, a mixture of slurry and frothing agents are added into a flotation machine. A tube releases air into the tank of the machine and an agitator creates air bubbles at the bottom of the tank.

Minerals that are hydrophilic, such as gold, attach to the bubbles surface and are brought up to the top of the tank. Other minerals fall to the bottom of the tank and are discarded as tailings. Bubbles containing gold and other hydrophilic minerals accumulate at the top of the water level as froth. This froth is then scraped off to create a concentrate of gold and other hydrophilic minerals. Flotation creates high quality concentrates and is good at capturing fine gold.

The methods briefly explained above can yield a concentrate with a large proportion of gold comparative to other materials. Nevertheless, there is need separate the gold from the other remaining minerals before it can be sold. Methods like direct smelting can then be employed to recover gold. When using direct smelting, the high-grade concentrate is heated until the gold melts. The liquid is then cooled to form solid gold dore, a semi pure gold alloy, that can reach upwards of 95% purity.

Chemical leaching makes use of the chemical properties of gold to leach it from the ore, concentrate, or tailings. Leaching is commonly used in large scale mining operations but has been increasingly adopted in small scale mining because of its high gold recovery rate and low cost. For best results when using chemical leaching there is need to use a combination of preconcentration and mill leaching, as they lead to the least amount of waste, a short processing time for miners, and high gold recoveries. Some of the chemicals used for leaching are toxic e.g. cyanide compounds. When chemical leaching is employed, it is important for miners to handle the chemicals in a sound manner and to ensure that they use appropriate personal protective clothing to avoid health and environmental concerns.

Cyanide is highly toxic and great precautions must be taken when handling it. However, in contrast to mercury, cyanide is does not persist in the environment. Cyanide leaching should not be done on tailings where mercury is present because cyanide will from a soluble mercury cyanide complex, mobilising mercury to great distances.

The Minamata Convention on Mercury is an international treaty designed to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds. Zimbabwe on the 29th of December 2020 became the 116th country to ratify the Minamata Treaty and the 51st in Africa.

Commenting on the ban of mercury use Minister Environment, Climate Change, Tourism and Hospitality Industry Mangaliso Ndlovu said Mercury is a toxic pollutant that can circulate globally through the oceans and the atmosphere for years or even decades, and can cause significant harm to human health and the environment, sometimes very far from its point of origin. Acute or chronic exposure can be fatal; the World Health Organisation lists it as one of the top ten chemicals of major public health concern.

Mining Zimbabwe our core focus is the Zimbabwe Mining Industry, Zimbabwe Mining News, trends, new technologies being developed and used to improve this crucial sector, as well as new opportunities and investments arising from it.

lime in gold ore mining process | flotation, cyanidation - jxsc

lime in gold ore mining process | flotation, cyanidation - jxsc

Lime is a low-cost item that is widely used in gold beneficiation plants. The following is a systematic description of lime properties, its role in flotation, cyanidation, amalgamation and other mining operations, for your reference.

Lime has strong water absorption, and reacts with water to become calcium hydroxide (Ca(OH)2), commonly known as slaked lime or slaked lime. It has little solubility in aqueous solution, but it can further ionize calcium ions (Ca2+) and hydroxide ions (OH-) in aqueous solution, making the solution more alkaline.

(1) Adjust the concentration of heavy metal ions in the slurry to form poorly soluble compounds. This is an important adjustment method to eliminate some harmful ions. For example, the addition of OH-ions can cause many metal cations to form insoluble hydroxides. Commonly soluble hydroxides that are difficult to form in flotation are Al(OH)3, Cu(OH)2, Fe(OH)2, Fe(OH)3, Pb(OH)2, Zn(OH)2, etc.

(2) Adjust the ion concentration of the collector. The presence of a collector in a molecular or ionic state in water is closely related to the pH of the medium. Adjusting the pH adjusts the proportion of the collector in the molecular or ionic state of the water, and adjusts the degree of dissociation of the collector.

(3) Adjust the interaction between the collector and the mineral. The effect between the collector ion and the mineral surface is closely related to the pH of the slurry. The collector anion and OH- can compete on the mineral surface. The higher the pH, the greater the OH- ion concentration. It can repel the action of the collector anion.

(4) Adjust the concentration of the inhibitor. Some inhibitors are salts composed of strong bases and weak acids. For example, the commonly used inhibitor sodium silicate( NaO2SiO2) is that it can be hydrolyzed in water to make the pulp alkaline, pH value. The level directly affects its degree of hydrolysis. When pH < 9, the silicate (H2SiO3) molecule dominates; when pH = 9~13, HSiO-3 dominates; when pH > 13, SiO-3 dominates.

(5) Adjust the foaming ability of the foaming agent. The pH affects the foaming ability of the foaming agent. For example, the foaming capacity of pine oil (2# oil) increases as the pH of the medium increases.

(6) Adjust the dispersion and agglomeration of the slime. The pH adjusting agent used in practice is often a dispersing agent or agglomerating agent for the slime, which acts to disperse the pulp or agglomerate the pulp. For example, Ca2+ in lime can weaken the negative polarity of the quartz surface, reduce the electrostatic repulsion, and facilitate the adsorption of the ionic flocculant.

When flotation of various non-ferrous metal sulfide minerals (such as copper, lead, zinc, etc.) with xanthate collectors, the ore usually contains a certain amount of iron sulfide minerals, such as pyrite, marcasite, pyrrhotite, arsenopyrite, etc., inhibiting iron sulfide minerals with lime helps the target minerals to float.

In the treatment of gold-bearing polymetallic sulfide mineral ores with high content of valuable heavy metals (such as gold-containing polymetallic sulphide ores containing copper, copper, zinc, lead, zinc, antimony, arsenic, etc.), since these ores contain To eliminate harmful factors, in order to eliminate unfavorable factors, in the actual production process, the flotation process combining mixed flotation and separation flotation is usually used, and lime is commonly used to adjust the pH value, generally controlling the mixing flotation pH=7~ 8. Allow most of the useful sulfide minerals to float up, and then use the separation flotation process to control pH = 10~12 to inhibit the separation of pyrite and achieve the purpose of separation.

Furthermore, natural gold particles are susceptible to inhibition by Ca2+. When a certain amount of lime is present in the slurry, Ca2+ reacts with CO2 in the air entering the slurry to form a CaCO3 precipitate, which inhibits the flotation of natural gold particles.

The addition of lime in the flotation operation is usually carried out by adding the lime powder to the ore belt of the ball mill or adding lime milk or lime powder to the stirring tank before the flotation.

The role of lime in the flotation process is most apparently the effect on the properties of the flotation foam. When the amount of lime is appropriate, the formed foam is relatively stable and has a suitable viscosity; when the amount is large, the foam is too stable, the foam is sticky, and even causes a running phenomenon, making the production process difficult to operate and control. At the same time, due to the aggravation of the cohesive slime, and this cohesion often lacks selectivity, the foam concentrate often entrains a large amount of ore fine mud, which affects the quality of the concentrate. Therefore, the amount of lime added should be strictly controlled in the flotation production of gold mines, and it should be fully recognized.

Lime is an inorganic electrolyte, the dissociated Ca2+ ions are adsorbed on the surface of the slime, reducing or neutralizing the negative charge on the surface of the slime, causing the fine particles to agglomerate into larger agglomerates under the action of van der Waals force, thus in the actual production process. Many mines use it to add to the flotation concentrate concentration thickener, accelerate the slurry sedimentation speed, optimize the concentration and filtration operation, and prevent the occurrence of concentrate running.

In the cyanidation process, lime can be used as a de-pharmaceutic agent for the gold concentrate cyanide plant before the immersion thickener to remove harmful substances, prevent the occurrence of gold concentrate run-off phenomenon and reduce unnecessary losses; As a pre-alkali dipping agent, it is used to eliminate the unfavorable factors of the leaching reaction before leaching; it can be used as a protective base for leaching; it can be used as a regulator, used in the process of zinc powder replacement, etc.

The role of lime before cyanide leaching comes down to three aspects. On the one hand, for the gold concentrate cyanide plant, it is commonly used as a de-agent for the pre-dip grinding classification or thickener. By adjusting the pH value of the pulp, that is, the pH, the anion properties of the flotation reagents (such as collectors and foaming agents) are changed, and they are defeated by competition to achieve the purpose of falling off from the mineral surface. On the other hand, since it is a weak inorganic coagulant, it is used in a pre-dip thickener to eliminate the charge on the surface of the mineral, compress the electric double layer, and form fine aggregates in the slurry to form a clot and accelerate precipitation. Prevent thickeners from running and reduce unnecessary metal loss. Furthermore, by pre-dip alkali leaching (lime CaO leaching) treatment, the concentration of anion and cation in the slurry is adjusted, the leaching reaction conditions are improved, and unfavorable factors are eliminated.

During the production process, some cyanide plants use the lime powder in the ball mill grading system; some add lime milk or lime powder to the sand pump box of the thickener before entering the leaching; some cyanide plants add one or two alkalis separately. The dip tank is pre-impregnated. The alkaline leaching process before the cyanidation process controls the alkalinity between 4 and 8/10,000 (calculated as CaO).

During the production process, excessive addition of lime will accelerate the sedimentation and concentration rate of the ore particles, which is not conducive to normal operation (such as thickener operation), and at the same time, CaCO3 precipitates will be blocked to block the pipeline; on the contrary, the amount of addition is insufficient, which affects both The effect of the drug does not reach the purpose of pre-alkali soaking. In short, the amount of addition is not suitable, which is not conducive to the normal cyanide operation. Therefore, many cyanide plants do not add lime in the leaching and replacement operations without special circumstances.

To maintain the stability of the cyanide solution and reduce the chemical loss of cyanide, an appropriate amount of alkali must be added to the cyanide solution to maintain certain alkalinity (referred to as a protective base). Lime is usually utilized as this because of the nature of the lime itself. In the cyanide leaching and washing process, due to the addition of lime, favorable conditions for the leaching and washing environment of gold are created, and the functions are summarized as follows:

(4) The precipitation of the ore pellets can be accelerated during the washing process, which is beneficial to the washing operation. In the cyanide production process, especially for ores containing more sulfide components, it is usually necessary to control the concentration of lime in the leaching operation. For the gold concentrate cyanide plant, the CaO concentration of the general control leaching process is between 2 and 5/10,000.

In actual production, the amount of lime should be strictly controlled. An excessive amount of lime, which may be due to flocculation so that the viscosity of the slurry is increased to increase the diffusion resistance of the solvent, so that a corresponding increase in the content of impurities in the solution, the surface of the gold particles forming the thin film of calcium peroxide, sodium cyanide and gold and hinder the role of oxygen , the effect of reducing leaching; when there is an insufficient amount of lime, sodium cyanide consumption will increase on the one hand, the influence leaching index; on the other hand, increasing the pregnant solution turbidity, causing the washing machine to run thickener tank, affect the subsequent zinc replacement operations smoothly Wait.

In the process of cyanide production, the control of lime is not paid attention to, and many mines cause losses. The ore in Inner since excessive addition of lime the gold leaching rate by 5% to 10%; a Shandong ore Again, a certain period due to insufficient amount of addition of lime, sodium cyanide consumption multiplied by 4. 82kg / t Increase to 9. 20kg / t and so on.

In the zinc powder replacement process of the cyanide plant, it is also important to maintain the alkalinity (CaO amount) of the gold-containing liquid, ie, the precious liquid. The appropriate lime concentration can enhance the clarity of the noble liquid and improve the ion composition of the noble liquid. , changing the order of the displacement reaction, affecting the rate of displacement reaction and the consumption of zinc powder, thereby affecting the replacement rate of gold. In the replacement operation, the role of lime comes down to the following aspects:

(2) By controlling the pH value, avoiding the formation of Zn(OH)2 and covering the zinc surface hinders the precipitation of gold. At the same time, hydrogen can be avoided in the alkaline solution to reduce the consumption of zinc powder;

(3) Change the impurity ions and their reaction state and sequence during the displacement reaction, prolong the service life of the replacement golden cabinet (filter press), and improve the replacement rate.

It is generally believed that when the concentration of CaO is low, impurities in the noble liquid are mainly formed by active ions, and the replacement process is mainly chemical reaction. During the high-temperature season, the activity of impurity ions (such as Cu2+ ions) is enhanced, the displacement reaction is accelerated, and the product clogs the filter cloth, resulting in a decrease in the processing capacity of the golden cabinet and a decrease in life. When the concentration of CaO is high, the impurities in the noble liquid are mainly in the form of compounds (such as hydroxides) and flocs (such as silica mud), and the replacement process is mainly physical change. That is, when the precious liquid passes through the filter cloth of the filter press, the compound, the floc or the like forms a film on the surface of the filter cloth, which weakens the water permeability of the filter cloth, causes the processing capacity of the filter press to decrease, and the life of the golden cabinet decreases. When the CaO concentration is appropriate, the impurities in the noble solution coexist in the form of active ions and compounds. At this time, the chemical and physical changes coexist in the replacement process, and the chemical changes at this time follow the order of elemental activity.

In the production process, due to the inattention to the control of the CaO concentration in the precious liquid, the life of the golden cabinet is reduced, which increases the cost and enhances the labor intensity of the workers. In this respect, a mine in Shandong has a painful lesson. The mine has been released 46 times in August and September of 1989, and it has been released three times in 24 hours.

Generally speaking, for the gold concentrate zinc powder replacement cyanide plant, the CaO concentration in the noble liquid is controlled between 3 and 8/10,000 in actual production, which can meet the service life of the replacement golden cabinet and guarantee Zinc powder consumption and gold replacement rate ensure the quality of gold mud products. In the production process, if the amount of lime is too much, in the presence of suspended SiO2 particles and excess Pb(AC)2, colloidal calcium silicate and calcium lead chlorate will form on the zinc surface, which will deteriorate the gold. Precipitation effect. On the other hand, if the amount of lime is small, the turbidity of the noble liquid is large, which affects the quality of the gold mud. At the same time, due to the small alkalinity, zinc easily reacts to generate hydrogen to increase the consumption of zinc powder. Therefore, it is necessary to strengthen the control of lime in the zinc powder replacement operation.

(1) The effect of amalgamation is affected by adjusting the pH value. The pH of the slurry has a great influence on the effect of the mercury mixing operation. In an acidic medium, the surface of the base metal attached to the surface of mercury is clean and promotes the wettability of mercury to gold. However, in an acidic medium, the slime cannot be agglomerated. On the contrary, the contamination of gold by the slime hinders the mercury to gold. Wetting. Therefore, lime is usually used to increase the pH value of the slurry, to agglomerate the slime, and to consume the unfavorable factors that hinder the wetting of gold by the contamination of the gold particles by the slime. Usually, the mercury mixing operation pH= 8. 0~ 8. 5 is appropriate.

(2) Inhibit the activity of sulfides in the slurry and prevent the mercury plate from getting sick. In the case of external amalgamation, sometimes sulfur or sulfide and mercury can cause mercury to pulverize, and black spots are formed on the mercury plate, which makes the mercury plate lose the ability to capture gold. This phenomenon especially includes arsenic sulfide, barium sulfide and ore in the ore. It is especially serious when strontium sulfide is used. Once this phenomenon occurs, the production of lime can be increased by increasing the amount of lime, increasing the pH of the slurry and inhibiting the activity of the sulfide.

(3) Prevent metal sulfide from adhering to the mercury plate and deteriorate the amalgamation operation. When the ore is treated with gold-containing polymetallic sulphides, metal sulfides often adhere to the mercury plate, which deteriorates the phenomenon of amalgamation. To eliminate this phenomenon, the amount of lime is often used in production, and sometimes the pH must be 12 or more. It can be solved.

(4) Elimination of magnetic amalgam in internal amalgamation operations. In the case of internal amalgamation in a non-alkaline medium, a magnetic amalgam is sometimes generated to cause the iron mineral to be mixed into the amalgam, so that the internal amalgam is mostly carried out in an alkaline medium. Lime is generally used to adjust the alkalinity of the slurry, which is used in an amount of 2% to 4% of the charge.

(1) Substituting sodium hydroxide (NaOH) as an absorbent for HCN gas in the acidification recovery process of cyanide wastewater. However, its use has great limitations, and there is no precedent in the country. According to reports: The Flinfloon Concentrator in Canada uses lime milk, which is atomized by a special device to react HCN gas with the absorbent Ca(OH)2 to form calcium cyanide for reuse.

Based on a large amount of data, this paper summarizes the role and control of lime in flotation, cyanidation, amalgamation and other operations in gold mines based on the system of years of production experience. Due to the limited level, there are inevitably many shortcomings, and many criticisms and exchanges are expected. Its purpose is to inspire and attract experience.

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