efficient use of alternative fuels cement americas
Firstly, since alternative fuels arent homogenous, they can create a lot of process instability. They also often contain high moisture content, which can limit kiln capacity. Then theres the challenge of chlorine byproducts, and of course the cost although this has been alleviated in many places by government incentives.
Emissions and production losses both stem from process inefficiencies. For these reasons, it could be concluded that alternative fuels necessarily cause a less efficient production process and manufacturers must simply weigh these costs against the benefits (whether financial, where grants are available, or environmental).
However, at Seebo they have seen firsthand how many cement manufacturers experience periods of high efficiency using alternative fuels indicating that they are capable of operating exceptionally, regardless of the fuel type.
Thats because where these Key Performance Indicators (KPIs) arent reached, it has nothing to do with alternative fuel usage per se but rather stems from the very same process inefficiencies that cause precisely the same losses at cement plants which still use coal.
In short: process inefficiencies are causing your production losses, not alternative fuels. The real challenge is to eliminate those inefficiencies and find the optimal process settings to enable stable operations with or without alternative fuels.
Overcoming The Limits Of Human Decision MakingCement manufacturing plants rely on human decision making. Your teams take dozens of manual decisions every single day, to ensure a stable, efficient process.
The problem is that human decision making is inherently limited. Even with the best process experts and production teams, it is impossible to analyze all the data, all the time particular considering that cement production is a uniquely complex process, with many complications and dynamic factors, from raw material variances to traceability. And then theres the fact that process inefficiencies are usually the result of complex interrelationships between multiple data tags.
Expert Systems Still Rely On Human Decision-MakingExpert Systems do provide some level of automation. But ultimately they rely on the decisions and calculations of your process experts. Whats more, Expert Systems cant adapt to changes in the process they need your process experts for that.
The kiln was actually achieving higher-than-average efficiency rates some 40% of the time. That means the potential for improvement is already there. The question is: how can they increase the amount of time the kiln is operating at those levels?
Revealing The Hidden Causes Of Process InefficienciesUsing automated root-cause analysis, their process experts were able to identify the hidden causes of their production losses and gain clear recommendations on how to prevent those process inefficiencies.
First, Seebo unified all the data from the line into a single schema, where its enriched and cleansed from raw material data, to process and quality data, to data on weather conditions and alternative fuels characteristics.
Next, Process-Based Artificial Intelligence embeds the algorithms with the context of the unique plant topology and expertise in the cement manufacturing process. This enables the algorithms to navigate through the unique complexities of each production process and truly understand the data in-context, providing a continuous, multivariate analysis that reveals important new insights that were previously hidden.
For example, the team discovered that when the cyclone material temperature is above 800 degrees, and simultaneously the kiln oxygen level was between 1.5% and 2%, the likelihood of a problem with the Kiln AMP increased very significantly.
This is an important insight that the process experts could never have figured out on their own since both of those tags remained within their permitted ranges! It was only the unique combination of those two specific ranges of tag values that was causing the losses.
Process Mastership With Artificial IntelligenceNext, Seebo created Predictive Recommendations, which identify the optimal process settings. For example, the team now has recommended optimal values for the cyclone material temperature and kiln oxygen level, to minimize instances of Kiln AMP inefficiencies as much as possible without negatively impacting other production parameters.
These recommendations are then turned into Proactive Alerts, which are delivered to the production team via a simple, intuitive screen as soon as process inefficiencies occur. The alerts include a clear description of the root-causes, and Standard Operating Procedures, so production teams know exactly what to do to fix those issues before losses occur.
You CAN Still Run An Efficient PlantIn conclusion, running an efficient cement plant has nothing to do with the fuel you use. By eliminating process inefficiencies and identifying the optimal process settings, cement manufacturers can run efficient, competitive operations using alternative fuel. Specifically:
efficient manufacturing could slash cement-based greenhouse gas emissions - the academic times
With more energy-efficient methods for production and use, Brazil's cement industry can more than halve its carbon dioxide emissions in the next 30 years while saving nearly $700 million, according to a new analysis and the reductions could be much deeper, when accounting for cement products' absorption of carbon dioxide from the air.
In a paper published April 5 in theJournal of Industrial Ecology, Brazilian researchers crafted a new roadmap for the greenhouse gas emissions-heavy industry thatthey said can also be adopted in many other countries. Itincludes a higher use of filler materials when making concrete and a larger reliance on ready-mix concrete and mortar.
The group also suggested that Brazil should alter its tax incentives and create a carbon tax to spur these changes more quickly, as limited time remains to decarbonize society fast enough to limit the extent of climate change.
The production of cement, the stone-based powder used to create construction materials such as concrete and mortar, is one of the largest sources of greenhouse gases on the planet. The cement industry emitted 4.1 billion metric tons ofcarbon dioxide in 2019, about 8% of global emissions, and Brazil is home to the 12th-largest market. Most of the carbon dioxide is produced when limestone and clay are heated in a calcination reaction to create clinker, which is used as a binder in cement.
The new study expands on two emissions scenarios through 2050 that were created by Brazilian cement trade associations: a business-as-usual scenario and a low-carbon scenario. The latter focused on the production of cement and included improving the energy efficiency of cement plants, using alternative fuels and reducing the use of clinker.
But the low-carbon roadmap did not consider the carbon-dioxide emissions that occur when cement is used in products such as concrete and mortar, sources that are explored less often, said Daniel Reis, an author of the study and a postdoctoral researcher of civil engineering at the University of So Paulo.
In addition to the preexisting low-carbon scenario, the researchers created a second low-carbon roadmap with a focus on reducing emissions when cement is used to make other materials. The scenario includes higher industrial production of concrete and mortar rather than mixing them on-site, as these "ready-mix" products require less carbon-dioxide emissions. It also involves substituting as much as 70% of cement with filler materials during mixing and using efficient planetary concrete mixers at concrete production plants.
Combining both low-carbon scenarios efficiency improvements in cement production and use would reduce up to 56% of the carbon-dioxide emissions expected under the business-as-usual scenario, according to the analysis. The new set of cement-use improvements accounted for a 22% decrease.
The researchers also noted that the reductions could be brought to 82% when considering the carbon dioxide absorbed by cement-based products through 2050, which happens when the greenhouse gas enters pores and reacts with the material.
This process is not normally included in industry emissions roadmaps given the relatively little research behind it, the researchers said, but it could be accelerated in cement products with a high proportion of filler, as proposed in the second low-carbon scenario.
Reis said the solutions in the second low-carbon scenario are much cheaper than other options such as carbon capture and storage, which removes carbon dioxide directly from the air. Between 2018 and 2050, the combined measures would save $695 million, or $1.36 per ton of carbon dioxide, making them more viable and easily scalable, Reis said.
The authors said that public policies are important for promoting low-emission measures, and that changes in Brazil's policies could incentivize them more effectively. The current tax structure discourages the use of planetary mixers in favor of on-site concrete trucks, and most environmental policies don't take into account the usage side of cement captured in the second scenario, they said.
According to Reis, a tax on carbon can also encourage emission-reducing solutions in the industry, although he recommended a careful introduction so that the tax does not increase cement costs in a way that impacts developing nations with a preexisting housing deficit.
Emissions from the cement industry account for less than 1% of Brazil's overall emissions of 2.2 billion metric tons of equivalent carbon dioxide, which it has pledged toreduce 37%below 2005 levels by 2025. But the country has been increasing emissions in recent years, especially as Amazon rainforest fires have intensified.
Although the analysis was constrained to the Brazilian cement industry, many of the methods included in the roadmaps can be adopted elsewhere, according to Reis. Global cement use and associated emissions are dominated by China, followed by India and the U.S.
"Practically all the measures explored in this article can be applied in other countries, except the industrialization of concrete and mortar, since in developed countries most of concrete and mortar is already industrialized," he said.
The study "Potential CO reduction and uptake due to industrialization and efficient cement use in Brazil by 2050," published April 5 in Journal of Industrial Ecology, was authored by Daniel Reis, Marco Quattrone, Sergio Pacca and Vanderley John, National Institute on Advanced EcoEfficient CementBased Technologies and University of So Paulo; Jhonathan Souza, University of So Paulo; and Katia Punhagui, Universidade Federal da Integrao LatinoAmericana.
control engineering | reduce energy consumption: cement production
Cement producers have faced a significant rise in energy costs with the introduction of dry-process kilns, with a record average consumption of 100-200 kWh per ton of cement, according to the 2009 Cement Plant Operations Handbook. This complex challenge, coupled with rising fuel and energy costs, has prompted cement manufacturers to implement energy management programs to help reduce costs while maintaining competitiveness and increasing profits.
Many cement producers have lowered energy costs up to 20% by adopting a holistic approach to industrial energy management. This strategic process helps customers identify cost-saving measures and evaluate the tools best suited to specific plant needs, including:
This is a time of unprecedented complexity for cement producers. Managing production while balancing supply, pricing, demand, process efficiencies, compliance with regulations, and other demands can be difficult. At the same time, the rising cost of energy, including water, air, gas, electric and steam (WAGES) resources, compounds these challenges.
As Paul Scheihing, technology manager, Industrial Technologies Program, U.S. Department of Energy, explained, The cost of purchasing the energy needed for production by an industrial facility is viewed as managed input and typically receives significant attention, while the use of that energy once it is inside the factory is often viewed as simply the cost of doing business. While not true in all industrial facilities, experience has shown that unless the facility actively manages energy use and has a documented plan for doing so, these facilities are significantly less energy efficient than they could be. Without performance indicators that relate energy consumption to production output, it is difficult to measure or document improvements in energy intensity.
For the first time in industrial applications, the automation control, optimization, and information solutions necessary to conquer this energy challenge are in place or readily available to be applied immediately to achieve measurable results.
Prior to beginning any energy management program, conducting an energy assessment can help companies identify a wide range of changes that they can make to help reduce consumption. These can be simple, such as a walk-through of a building or facility to identify quick-hit opportunities, or much more detailed efforts. Assessments can help establish the scope of an energy savings effort, define key metrics, and put resources in place to take a holistic view of energy for the entire organization.
Recommendations resulting from the assessment may include low-investment or no-investment behavioral modifications, such as shifting maintenance operations to nonpeak times, or may be more involved, such as programming changes to equipment. Evaluation and prioritization of capital improvement opportunities can also be included in the analyses.
After an assessment, the first step toward managing energy consumption is to gain awareness of energy usage patterns and trends throughout the facility. Building management personnel can leverage the facilitys metering infrastructure, including power monitoring devices, historical utility bills, and prior energy or process assessments, to collect data about all the energy resources in relation to equipment usage and environmental conditions. This process should include all points where energy is used, from an industrial process to critical building systems.
This data is then logged and time-stamped in an energy historian software program in order to establish trends or discrepancies in energy quality and consumption, and to establish benchmarks for future improvement. With this big-picture view of a facilitys overall WAGES use, building management personnel can then identify and make operational changes to help reduce energy consumption and related costs, such as shedding loads or temporarily lowering power levels when the facility is approaching peak use.
Production equipment monitoring also provides knowledge about how specific assets consume energy. Identify useful data collection points across equipment and processes, and program the information system to store and analyze that data.
Load-profiling exercises chart energy consumption patterns by measuring and recording energy usage to identify peak demand periods, correlate consumption with facility activities and production in real time, and forecast energy demand.
With a log of historical data, building management staff can identify power quality issues, such as voltage sags or harmonics that can cause damage to equipment inside the plant and cause power factor problems on the energy grid. By knowing these risks, manufacturers can better protect their equipment and avoid incurring penalty fees from utility companies.
To justify the cost of an emergency load-shedding system, simply identify what a power outage would cost in lost production, using data collected during the assessments conducted earlier. Most cement producers find that an emergency load-shedding solution will pay for itself in one or two outages.
By reviewing energy usage data collected previously, cement producers can reveal where energy dollars are consumed, and in what proportion. This can help allocate costs by department, process, or facility; verify the accuracy of utility bills through shadow billing; and evaluate alternate energy rates and contracts.
A demand management system limits energy demand through load shedding and peak shaving strategies. It helps reduce demand charges and manage real-time power purchases or to minimize load during a curtailment period.
For example, a steel mill was using 90,000 MWh of electrical energy per month, at a cost of $2.7 million each year. By replacing the facilitys unreliable demand management system and updating its control algorithms to more efficiently shed loads, improve power factor, and reduce voltage sags, the $300,000 system experienced a complete payback in five months. In addition, the company is enjoying an ongoing savings of $70,000 per month from reduced damage levels.
Nearly 70% of all electricity used in industry is consumed by some type of motor-driven system. In a 10-year life cycle, a motor could accumulate energy costs amounting to 100 times its original purchase value.
In cement plants, VFDs are used to save energy and control process parameters, and retention times in applications with variable torque characteristics such as gas flow and fluid flow or in constant torque applications such as material handling and grinding equipment. Drives also are used to power roller mills for grinding different blaine of slag for cement, and for starting and running multiple roller mills, ball mills, and overland conveyors.
A China-based cement plant used VFDs to significantly reduce its energy consumption in its dry-process kilns, responsible for production of 1.4 million tons of cement each year. Traditional damper control systems used a fixed amount of energy, so fans at the plant always ran at full capacity even when the facility wasnt producing productwasting energy and causing unnecessary wear on the equipment. By using variable frequency drives to automate the speed control of its kiln head exhaust fan, kiln main electric fan, high-temperature fan, coal mill exhaust fan, and kiln tail exhaust fans, the system now only uses the amount of energy necessary to produce the required amount of airflow. As a result, the company reduced specific energy consumption by 10%, generating annual savings of $124,000.
Power factor (PF) measures how well cement producers use the power they draw from the grid. A PF of one is equivalent to 100% efficiency; in other words, all the power drawn is used. A PF of zero means there is an entirely reactive power flow.
To improve power factor, companies can implement of VFDs, use synchronous motors (such motors inherently have a PF of one), or install power factor correction capacitors. Power factor correction capacitors are used to improve the poor power factor of induction motors.
Once cement producers have addressed opportunities for improved efficiency, the next step is to examine opportunities for optimizing the entire process. Indeed, controlling a major process unit effectively usually means dealing with multivariable systems, but it is extremely unlikely that treating each control loop independently will provide optimal control since in most situations, the control action of one loop affects the other loops. Model predictive control (MPC) technology, a multivariable control algorithm, can provide:
MPC technology allows the controller to receive information about the current operating condition of the process, then uses a model to predict process response to a sequence of future moves in manipulated inputs over a specified timeline, or prediction horizon. Next, an optimal control problem, solved online, determines the best sequence of future moves in multiple manipulated variables to minimize a particular objective function while obeying various process constraints. A fraction of the resulting control trajectory is then applied to the process and new process measurements reflecting modified operating conditions are obtained, allowing comparison of process outputs to desired reference trajectories. With this new information, the system repeats the optimization and control move process.
MPC systems can deliver optimization across key areas of the production process through applications for raw material preparation, including pyro-processing, cement grinding, and material blending. Energy savings can be generated by optimizing the combustion process, controlling temperature profiles, optimizing the heat recuperation process, and others. On average, MPC systems allow cement plants to reduce their energy consumption by 3% to 5%, as well as provide better product quality and capacity improvements.
Armed with optimized production information, manufacturers can then project, in advance, how much energy will be required for similar loads or batches. Cement producers can then include energy requirements in resource planning and scheduling decisions in the same way they consider the availability of raw materials or other inputs on the bill of materials.
Empirically tying WAGES consumption requirements to the bill of materials allows a plant manager or production scheduling manager to make proactive production decisions and better manage energy investments in a way that will generate a greater return. For example, by knowing that certain cement batches require more natural resources, managers can move those batches outside peak windows.
At this point in the industrial energy management process, energy and its associated greenhouse gas emissions are no longer fixed allocations that are simply part of unavoidable overhead. Manufacturers who add WAGES resources to the bill of materials can actively manage it as an input to achieve higher profitability. In addition, this unit-level energy consumption information becomes valuable input to sustainability scorecards and other reporting mechanisms, allowing companies to better optimize their full supply chain to enhance sustainability and energy programs.
For example, in the cement factory of the future, a manufacturer might wish to enhance operations to support an ideal sustainability score. The company might choose a production facility based on the price of slurry, and on the potential carbon or energy footprint of shipping the raw materials to the facility. Additionally, the transportation routes for the outbound product can be optimized to account for weather factors that might impact the energy needed to store the product.
Manufacturers who have adopted this holistic approach to energy management have been able to do so by leveraging existing automation and power system investments to make more of their WAGES resources. Using intelligent automation solutions to get the big picture of energy use in a cement plant helps to identify where operational changes can be made to reduce energy consumption and costs.
VFDs employ affinity laws to reduce energy use by using the minimum amount required by the motor application. For example, in centrifugal applications such as fans and pumps, a reduction in speed translates to a proportional reduction in flow (head pressure varies as the square of speed). A reduction in speed also translates into a reduction in energy (power varies as the cube of speed). Therefore, a flow rate of 50% equates to a power requirement of only 12.5%. In other words, a fan speed of 80% equates to a 50% reduction in energy.
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
environmental impact of portland cement production - sciencedirect
With the current focus on sustainability, it is necessary to evaluate cements environmental impact properly, especially when developing new green concrete types. Therefore, this chapter investigates the available literature on every process concerned during the production of cement. Inventory data on energy use, CO2, PM10, SOx and NOx emissions are collected. Alternatives and improvement are briefly described regarding energy performance and mineralogy changes that it induces for clinker.
cement production - metso
Cement producers utilizing alternative fuels such as refuse derived fuel (RDF) and solid recovered fuel (SRF) can gain a substantial competitive edge if the alternative fuel meets the required standards.
In many cases, however, input waste streams contain diverse materials not suitable for co-processing in the cement kiln. A well-designed alternative fuel production process ensures the optimal quality.
To maximize the energy production with the lowest possible emissions, homogenous grain size, high calorific value, controlled material composition, the removal of fines, low chloride and a stable humidity content are a must.
Effective pre-shredding removes unwanted items so they do not contaminate the final fuel product. For RDF and SRF production, light materials like plastic products and other dry combustibles are useful, while rocks, cement lumps, sneakers, boots, wet newspapers and metals reduce the calorific value.
Opening waste bags and reducing the size of waste by pre-shredding ensures that unwanted items can be screened and separated from the process. Later, when the material content of the alternative fuel content is optimal, fine shedding turns it into the right shape and size for combustion to maximize energy generation.
energy and material efficiency in cement industry india
Todays growing population have been one of the factors of many changes that have been taking place all around the world. Growth of current population demands more houses/buildings/transport etc. Constructing more houses & buildings means that more concrete and other material are required. Concrete plays a major role in construction. In this period, concrete is made using mixtures of cement, water and aggregates containing mineral components, chemical admixtures and fibres.
Throughout the world total cement consumption has reached 3,312 Mt in 2010. Global consumption continued to rise moving to 3,585 Mt in 2011, and estimated consumption for 2013 is over 3,900 Mt. This can be seen on the graph below.(Gorbatenko and Sharabaroff, 2014)
Figure 1 shows an increase in global cement demand is due to economic expansion in emerging economies. Urbanization and industrialization has increased the demand for cement throughout the world. Annual growth rates for china has reached 16% in 2010 and, over 2011 and 2012 Chinas economy approaches a sustainable growth rate.
China is the world largest cement producers and in 2012 their cement consumption is 2160.0 (Mta) and in the same year Indian cement industry has consumed around 241.8 (Mta). Indian Cement consumption is 11.19% compared to Chinas cement consumption for that year.
Economic growth and energy consumption are very closely related, Non availability of energy and material will have a downfall on the countrys economic growth. Energy demand in industries are increasing to 0.5% per year. Indian industrial demands 4.5% of industrial energy use worldwide, and 44.8% of the total energy use in the year of 2006/07. As India being the second Largest cement producers in the world after China it consumed 13.5% of the total industrial energy in the year of 2006-2007. (Thirugnanasambanda and Hasanuzzaman, 2011)
Production of cement clinker using limestone and chalk by heating limestone at temperature above 950C demands most of the energy. Clinker production emits CO2 as a by-product when calcination of limestone takes place. Indian cement industry is highly advanced compared to other countries as they have achieved the best level of specific energy consumption in both thermal energy and electrical energy, while having 680kcal/kg of clinker (2.85GJ/ton clinker) and 66kWh/tonne of cement as their best achieved number. (Confederation of Indian Industry, 2013)
This report reviews the main manufacturing process and the use of latest technologies in Indian cement sector. An overview of the current industry structure, regulation, production, import and export status are reviewed.
Cement manufactured at thousands of plants, the industry is worldwide where international firms account for only 30% of the worldwide market (European commission, 1997). The most vital market for cement is the construction industry where its combined with water to make concrete. Manufacturing industries use up to one third of global energy use. CO2 emissions amount released from direct industries is up to 6.7 (Gt) which is about 25% of total worldwide emissions of which 30% comes from the iron and steel industry, 27% from non-metallic minerals (mainly cement) and 16% from chemicals and petrochemicals productions(IEA,2008). Cement production requires heating, calcining and sintering of blended and ground materials to form clicker. Which causes CO2 to be produced in a large quantity due to the production of lime, which is the key ingredient in cement.
The raw materials that are needed to produce cement such as Limestone and clay are blasted from the quarry. Quarying done through drilling, blasting and using heavy earth moving equipment such as bulldozers and dump trucks.
The collected raw materials are loaded into a dumper and transported to the factory where it goes through the next stage. Limestone supplies CaCO3 for the cement production where Silica, Alumina, and Iron are considered to be other raw materials. The typical limestone used in cement production has 75-90% CaCO3 in a raw feed. The reminder is magnesium carbonate (MgCO3)and impurities. The lime and silica provides the main strength to cement where as the iron reduces the reaction temperatue and gives the cement its characteristics grey colour.
The raw materials then taken to the cement factory where the raw materials get crushed and transported to the plant by conveyor. Then the materials are stored before they are homogenized. The limestone size is reduced to 25mm buy feeding into a primary and secondary crusher. A further reduction in the inlet size can be made by passing it through a tertiary crusher. In the storage hopper some iron, bauxite, quartzite and silica to achieve the required raw feed compositions. These materials can be stored in silos or hoppers. These additives prevent any natural deviation from compositions of raw materials.
The stored materials then go through the raw mill where they are finely grounded to produce raw mix. A ball mill or vertical roller mill (VRM) are used during a grinding process. The raw mix is dried using the part of the excess heat from the kiln in this stage. Various sizes of balls are used inside the ball mills. The larger sized balls are used for impact grinding and the smaller balls for attrition grinding. A compression principle is used to grind the raw materials in a VRM grinding process. The choice between a ball mill is depend on the moisture content of the raw material, the size of the plant, the abrasiveness of the material, the energy consumption levels, reliability and economic viability.
At the core of the production process is a rotary kiln where limestone and clay are heated to approximately 1450C. the semi-finished product clinker is created by sintering or heating it until it coalesces into solid material. The flame can be produced by powdered materials such as coal, petroleum coke or by natural gas. To reduce the natural chemical variation in the various raw materials, it is necessary to blend and homogenize the raw material efficiently. Increasing the relative proportion of blending additives may reduce the amount of clinker used. This consequently will reduce the specific energy consumption of the final product. Latest pre heater towers contain a combustion chamber. This chamber is commonly known as pre-calciner, in this stage the raw materials are calcined to produce CO2.
The collected clinker is then added with Gypsum and grinded to a fine product traditional Portland cement. Other secondary additives and cementitious materials can also be added to make a blended cement.
2.2.1 Air emissions Air emissions are generated in many forms in a cement industry. Handling, storage of intermediate, operation of kiln systems, clinker coolers and mills where they can mostly be generated. Particulate Matter emissions(PM) has most impacts of cement and lime manufacturing. Particulate Matter emissions develop from intermediate and finial material handling such as crushing and grinding of raw materials. They can also be found in handling and storage of solid fuels.
2.2.2 Energy consumption and fuels- cement and lime manufacturing are energy intensive industries where electric energy and fuel costs can be 40%-50% of total production costs. Production of cement clinker involves the use of dry process kiln with multistage preheating and precalcination (PHP kilns). PHP kilns have the lowest heat consumption due to the high heat recovery from kiln gas in the cyclones, and low kiln heat losses. Long dry (LD), semidry, semi wet, and wet process kilns are known to be more energy consuming. The most commonly used fuel in the cement industry is pulverized coal (Black coal and lignite) where the lower cost of petroleum coke (Pet-coke) has resulted in increased use of this fuel type. Coal and pet-coke generate higher emissions of greenhouse gases than fuel oil and natural gas.
2.2.3 Solid wastes- sources of solid waste in cement and lime manufacturing include clinker production waste mainly consumed from spoil rocks which are removed from the raw materials during the raw preparation. Another form of waste stream involves the kiln dust removed from the bypass flow and the stack when its not recycled in the process. Other waste materials which can be produced during the process may include alkali or chloride/fluoride containing dust build up from the kiln.
2.2.5 Physical hazards- injuries during the manufacturing operations are related to slips, trips and falls. Activities related to maintenance of equipment, including crushers, mills, mill separators, fans, coolers, and belt conveyors represents a significant source of exposure to physical hazards.(IFC, 2007)
Dry process involves limestone, chalk and clay are crushed into gyratory crusher to get 2-5cm size pieces. The crushed particle then ground to get fine particles, then each material screened and then stored in a separate hopper. The powder is mixed using required proportions to get dry raw mix which is then stored in silos. Its kept in silos till its ready to be transferred into the rotary kiln. Raw materials are mixed using required proportions which ensures that average composition of the final product is maintained properly.
During wet process the raw materials are crushed, powdered and stored in silos. In order to remove adhering organic, matter the clay is washed with water in wash mills. The washed clay is then stored separately. Slurry is then formed by powdered limestone and wet clay are made to flow in channel and transfer to grinding mills where they are mixed. 38-40% water stored in slurry, stored in storage tanks where they kept ready to be transferred into rotary kiln.
Ordinary Portland cement (OPC)- 70% of Cement produced are this type of cement and they are sold in 3 grades as follows; 1. Grade 33, 2. Grade 43, 3. Grade 53. The grades are normally printed on the cement bags.
Portland blast furnace slag cement or Portland slag cement (BFSC or PSC) 10% of this type of cement is produced in India where the slag mixtures are 25%-60%. The blast furnace slag is produced from cast Iron where every ton of cast iron can produce up to 0.3tons of iron cast. Blast furnace slag cements that contains more than 50% of slag has good sulphate resistance.
Hydrophobic Cement- This type of cement is made by grinding the cement clinker with water repellent film which forms into a substance like oleic acid, this water repellent film forms around the cement particles while manufacturing process takes place. Formed water repellent prevents cement from setting during storage.
Figure 15 shows that PSC requires 38% of energy when compared to other kind of cements that are mentioned above. This is due to the energy demand for the process quenching/granulation, grinding, and energy needed when storing in silos. Portland pozzolana cement uses less energy consumption of 2.32 GJ/tonne.
Ordinary Portland cement (OPC) is the leading cement, its made of compounds produced from burning limestone and clay together using a rotary kiln at the temperature 1450C. Almost 40% of CO2 is produced during burning of fossil fuel to operate the kiln, other 50% is produced manufacturing process and the remaining 10% of CO2 is produced from transporting products.
Cement industry is very energy intensive and involves chemical combination of calcium carbonate (Limestone), Silica, Alumina, Iron ore and small amount of other materials. Cement production involves quarrying, preparing raw materials and production of clinker through heating the materials through massive rotary kilns at high temperature. (Schumacher and Sathaye, 1999)
Theoretical heat requirements for clinker making and the main substance of cement is calculated to be about 1.75 0.1 MJ per kg (taylor,1992). Cement production consist of different processes such as Wet process, Semi wet process, Semi dry, Lepol process and Dry Process. During the production of clinker two types of kilns are distinguished such as rotary kilns and shaft kilns.
During cement manufacturing Carbon dioxide emissions comes directly from combustion of fossil fuels and from calcining the limestone in the raw mix. Theres an indirect and smaller amount of CO2 is released from consumption of electricity which is also generated from fossil fuels. Roughly 50% of the CO2 emitted is from fuel and the other 50% originates from the conversion of the raw material.
Cement industry in India plays a major part in Indian economy by having more than one million people working on it, this has made Indian cement industry the second largest in the world (IBEF, 2015). By 2011 Indian cement industry has installed capacity of 300 tonnes by 2011 and expecting to increase to 600 million tonnes by 2020. (Confederation of Indian Industry, 2013). When installing capacity 99% dry process has been used. Indian cement industry has also been adopting to latest technologies for energy and material efficiency.
The greatest level achieved by the Indian cement industry is at about 680kcal/kg clinker, (2.85GJ/ton clinker) and used 66kWH per tonne cement.(Confederation of Indian Industry, 2013) However Indian cement industry also uses plants which are installed before the 1990s which tend to operate using higher energy consumption level. In order to improve the situation Cement industry in India have been retrofitting new technologies to minimize those plants energy consumption level closer to the best achieved level.
The cement sector is one of the largest emitter of greenhouse gas CO2, however the Indian cement industry has been putting efforts towards emissions control, preservation of ecology and voluntary initiatives such as corporate responsibility for environmental protection (CREP). Moreover, the industry tries to reduce carbon footprint by adopting the best available technologies and environmental practices which has been reflected in the achievement of reducing CO2 emissions to an industrial average of 0.719 tonne CO2 per tonne of cement produced which is quite a lot compared to CO2 produced on 1996 which is about 1.12 tonne. (Confederation of Indian Industry, 2013)
IC is used as energy consumption indicator using the ratio between consumed energy and the value of production obtained using that energy. For energy analysis in Cement production in India specific energy consumption(SEC) is used and it is defined as;
Cement plant in India consists of Electrical energy and thermal energy. Best Indian cement plants Average specific energy consumption (SEC) for electrical energy is 63kWh/T of cement and average specific energy consumption (SEC) for thermal energy is 663kCal/kg of Clinker. (Anamika, Yogesh and Shammi, 2004)
Energy consumption can vary depending on the technology that has been used in cement manufacturing. Dry process of cement manufacturing uses more electrical energy and less thermal energy when compared to Wet process. Around 29% of the expense is spent on energy, 27% spent on raw materials, 32% spent on labour and 12% on depreciation. (Schumacher and Sathaye, 1999).
94% of the thermal energy is satisfied by coal in Indian cement industry. The rest of the energy used is met by fuel oil and high speed diesel oil. Due to power cuts and interruption of power affects the industry in a negative way causing production losses, low capacity utilization, thermal losses while reheating etc. In 1993, 974 GWh of electricity produced onsite (Government of India, Annual survey of industry, 1993). Due to insufficient data availability for Indian cement industry makes the energy analysis challenging.
NOTE: Electrical energy consumption of cement manufacturing is estimated using the electrical energy consumed per tonne of cement produced. Thermal energy is estimated using thermal energy consumed per tonne of clinker.
Total amount of cement produced by the company Ultra Cement is shown in figure 12. Power consumption from 2004-2012 has been collected and plotted on the graph below. Power consumption in Cement production means the amount of electrical energy is supplied to operate an electrical appliance, in this case the power consumption indicates the amount of electrical energy used to make Cement in Ultra Cements India. Grey area represents the specific energy consumption which has been worked out using (SEC) as explained in chapter 3.1. Annual Power consumption was high during 2005-2006 using up to 89kWh and the lowest amount of power consumed during 2011-2012 using up to 81kWh. This change is due to the improvements in machineries that has been used.
Annual Cement production and the power consumption for ACC limited is shown on the graph below. The highest power consumed by ACC limited is 89kWh during 2007-2008 where the annual cement production for that time period was 19.9MT. However, when comparing to the results obtained during 2011-2012 only 84kWh power consumed and 23.6MT of cement produced having the lowest energy consumption of 3.559 kWh/MT.
Annual power consumption for Ambuja cement during year 2005-2006 left blank due to unavailability of data. The lowest power consumed by Ambuja Cement is during 2004-05 and 2007-2008 where they have used 84kWh and produced 10.4 and 16.9MT of cements. The lowest specific energy consumed was during 2006-2007 with (SEC) 3.805kWh/MT.
India Cements limited has a higher power consumption compared to the other plants thats mentioned above. The highest amount of power consumed is during 2005-2006 and 2006-2007 where they consumed 130kWh of power and produced 7.3 and 8.4MT cement. Specific energy consumption (SEC) for the mentioned time periods were 17.808kWh/MT and 15.476 kWh/MT. which is fairly high compared to other plants.
The highest specific energy is consumed by Madras Cements during 2004-2005 having 18.947 kWh/MT where the company has produced only 3.8MT of cement while using 72kWh of power. Madras cement seems to have improved their energy efficiency since and the results can be seen during the production in 2011-2012 where the specific energy consumption is reduced to 10.4kWh/MT.
One of the main fuel for burning Portland Cement is clinker coal. Cement industry in India uses up to 3.5 to 4.0 million tons of coal a year, (Mohan, 1969). ACC Limited and Ambuja Cement had the most Coal consumption compared to other Cement companies thats mentioned on the graph above. Data for Ultratech cement is not found between 2005-2008 which is left empty hence its not shown on the graph. However, since 2009-2012 coal consumption by them kept below 0.003 (GJ).
There are six major varieties of coal which have been used in India known as Raniganj, Jharia, Talcher, Assam, Kutch Lignite and Neyveli Lignite coals. Raniganj, Jharia and Assam coals are good varieties of Indian coal which have high carbon and low ash content. (SAWHNEY and Verma, 1989)
From figure 22, it is observed that the India cements had the highest specific energy consumption during 2004-2007 compared to other cement plants that are mentioned on figure 22. During the period, 2005-2006 India cements had their highest SEC of 17.808 KWh/MT. This is due to having 130KWh power consumed in that period while 7.3MT of cement produced.
India is the second largest cement producers in the world, having 130 large cement plants, 206 mini cement plants comprising with 13 rotary kiln plants and 193 vertical shaft kiln plants. Indian cement industry has large cement companies such as Holcim, Lafarge, ACC, Ambuja Cement and Lafarge Birla Cement. (Thirugnanasambanda and Hasanuzzaman, 2011). Indian Cement industry is broadly home-grown while having the countrys largest firm producing 22% of the domestic market called Ultratech Cement, with ACC (50% owned by Holcim) and Ambuja (50% owned by Holcim) while having 15% and 13% shares respectively.
Other top players are respectively Jaiprakash Associates (10%), The India Cements Ltd (7%), Shree Cements (6%), Century Textiles and Industries(5%), Lafarge(5%), Birla Cement(4%) and Binani Cement(4%).(G.C.M, 2013).
The per capita consumption of cement in India is 125kg which is a third of the world average. Production of cement rose from 23.5 m.t in 1983 to 44.1 m.t in 1989 and as of march 2007 the installed capacity of the cement industry produced up to 160 m.t. between 2005- 2006 four of the top five cement companies of the world entered into India through either mergers, acquisitions, joint ventures or green field projects. These include Frances Lafarge, Switzerlands Holicm, Italys Italcementi and Germanys Heidelberg cement. (Kumar, 2013)
As the growth in housing and infrastructure started to increase the demand for cement increased significantly which helped the cement industry to grow remarkably. The table below shows the collected data from the period of 1991 to 2006 of installed capacity, production and export quantity.
From the table below we can see that the clinker capacity and cement production in India are near enough equal which shows that the clinker produced throughout the process is used to make cement, reducing clinker wastes. Over 2012-2013 the clinker capacity stayed the same where cement production in India increased from 270Mt to 280Mt showing 1.85% growth rate annually. (Gorbatenko and Sharabaroff, 2014)
During 1996 Indian cement industry used to in fourth position in terms of their production following China, japan and the USA, and today they have improved their production with almost 390 million tonnes (MT) of cement production capacity making them the second largest in the world today after China.
In India cement prices have been subject to government control, under the dual pricing policy instituted in 1982. Cement units (other than mini plants) are required to sell a specified portion of their output at a fixed price. Where a remainder may be sold at the open market price. A system of freight equalization operates in a manner to ensure a uniform levy price throughout the country, theoretically compensating the regions furthest from cement plants for additional transport costs involved. The bulk of the levy cement allocations serve to meet the requirements of central and state government. The levy cement retention price (i.e. price ex-factory net of taxes and packing) was fixed at RS 339/tonne in 1982.
According The Hindu news, the price of cement in Chennai (south India) has reached to Rs. 400 for 50kg of cement. Whereas its old for Rs. 260 a bag in North India. (Manikandan, 2015) Reason for the increase in price is because of the marginal decline in demand and the average cement operating rates in the region is around 60% during 2011-2012 in south India.
Calcination process of limestone from combustion of fuels in kiln as well as from power stations during cement production releases CO2. In cement industry coal constitutes a major share in the fuels. Table 2 below shows the carbon dioxide intensity for each state in each year. This carbon dioxide includes only emissions from coal combustion.
The average value of carbon dioxide intensity of Indian cement industry worked out from the table is 0.0458. From the table above we can see that cement industries in Madhya Pradesh, Bihar, Andhra Pradesh, Karnataka and Maharashtra are the most carbon dioxide intensive. (Kumar Mandal and Madheswaran, 2010)
Alternative fuels and other similar measures focusing on the production facilities are of importance from an environmental perspective however they do not reduce the amount of CO2 produced. Production of Portland cement involves burning of limestone which means that a lot of CO2 is released due to calcination as well as combustion of fuels.
4.2.1 Calcination: in this step the yielded CO2 results from both fuel combustion and feedstock combustion. The CO2 found in flue gas is more concentrated than it is in conventional power plants. The largest portion of CO2 comes from this step.
4.2.3 Indirect Emission:This type of emissions released from the result of generating the power used for cement production. Mainly in the production of clinker grinding. CO2 emissions can also be found from the process of extraction and transportation. (Zhou et al., 2016)
Cement production consumes a lot of energy, as India is the second largest cement producers in the world it requires consumes a lot of energy. Cement production consumes 20% of total energy consumption involving both thermal and electrical energy. Electricity is required mainly during Raw material extraction, grinding, finished grinding and packaging. During the production of cement electricity also be used on Conveyors, compressors, fans and pumps. Indian plants mainly based on the dry process as it uses about 9% less power compared to conventional wet process. Another energy saving method thats being used in India is when the cement gets blended which consumes less power without affecting the quality.
Cement production in India uses up to 10 Billion kWh of electricity in 2005. Electricity is used to drive different motors in the plant such as compressors, fans conveyor belts, crushers etc. 60% of total electricity gets used in raw material grinding and cement grinding.
Producing a fine quality cement also requires a lot of electricity, in some cases improving thermal energy has led to an increase on electricity consumption. For example, grate cooler technique for cooling clinker reduces thermal energy where it requires a lot of electrical energy.
Figure 30 showing the energy saving options which can be applied to Indian cement industry, by having a factory automation in cement plants 5.78 GWh of energy can be saved. This is through using the available technology to monitor all the processes, control, regulation and optimisation systems.
Indian cement industry has a high potential for generation of renewable energy from different sources such as Wind, Solar, Small hydro, Biomass and cogeneration bagasse. It is estimated to have 896603 MW of potential renewable energy which can be consumed for the use in cement plants. This including Wind power potential of 102772 MW, Small hydro power of 19749 MW, Biomass power potential of 17538 MW, 500 MW which can be consumed from cogeneration in sugar mills and Solar power of 748990 MW. (Bhawan, 2016)
Cement sector has energy saving potential of 2190.3 GWh which can be achieved by choosing the right product mix. This believed to contribute 20% of the total consumption of the cement sector in 2005 and 1% of total industrial electricity consumption. (Rane,)
Use of alternative fuels and raw material can benefit cement manufacture in various ways, such as replacing demand for fossil fuels like coal and can avoid deposits of raw material sources such as limestone, bauxite and others. Alternative fuels can also benefit on an energy basis as it can help reduce CO2 emissions at plant level. One of the main issue of using alternative fuels and materials is that the available facilities and machines should be ensured that they can handle the alternative fuels and materials in a most efficient way. Moreover, when using alternative fuels and alternative raw materials the quality controls for cement products are done carefully and the waste with recoverable calorific or material value is selected.
Several factors such as potential impacts on health and safety of workers and public, plant emissions, existing operations and final product performance are considered when choosing an alternative materials and fuels.
Advanced mining with mine plan software can be used to reduce raw material additives, over-burden handling and enhanced mine life. Also Overland conveyors are used to transport crushed limestone will benefit when transporting for a long distance between mines and plants. Installation of mobile crushers can be beneficial for productivity improvement and installing radio controlled mines machinery monitoring system for better control and optimization.
Many of the components found in raw materials and fuels such as halogens, metals, and organic compounds are identical to the components found in wastes used as alternative fuels. Chlorine can be found in raw materials such as clay and limestone and in both coal and waste derived fuels. Moreover, Alkalis (Na2O and K2O) are normally found in the raw materials such as clay or shale, where they can also be found in alternative fuels and raw materials such as fly ash and blast furnace slag. Cement production undergoes quality control system whether they are conventional or alternative.
There are numerous alternative methods have been replacing the old method to ensure cement productions energy efficiency is kept to its minimum. Some of the alternative steps has been explained below:
Vertical Roller Mills with the latest generation classifier are being installed with mechanical recirculation system, High efficiency fans with high tension(HT) Variable frequency (VFD), automatic sampler and cross-belt analyser in the mill feed for better quality control and adaptive predictive control for mill operation for limestone with more than 5% moisture content and hardness classified as medium and soft. However, for limestone with low moisture content with less than 3% roller press with separator in finished mode can be installed with high efficiency separators and cyclones, Automatic sampler and cross belt analyser in the mill feeding for better quality control and adaptive control mill operation.(Confederation of Indian Industry, 2013)
4.6.2 Kiln and preheater system- Modern cement plant is equipped with six stage pre heaters with in-line or separate-line calciner, Kilns with volumetric loading of about 5-6.5tpd/cu.m and advanced automation system. Installation of high efficiency cyclones offers significant energy efficiency improvement opportunity in cement kilns. Six-stage preheater system offers pressure drop of about 300mmWC in latest designs. Oxygen enrichment is also an option for energy efficiency as well as increased alternative fuel utilization.
Indian cement industry also working on using kilns with zero waste heat concept which will help to utilizing all waste heat in process itself without a separate WHR system, recovery from kiln shell radiation, fluidized bed combustion kilns, cogeneration of cement and powder and limestone enrichment technology. These alternative will help Indian cement production to be energy and productivity efficient.
4.6.3 High efficiency clinker coolers-Indian cement industry has been successfully adopting to the reciprocating grate coolers where use of rotary cooler is getting wiped out. More than 50% of cement produced from kilns less than 10 years old and reciprocating coolers have become common practice in the industry. They have also use the enthalpy from the hot clinker which is then recovered to preheat the incoming secondary and tertiary air to improve thermal efficiency. Conventional grate coolers tend to provide a recuperation efficiency of 50-60%, depending on the mechanical condition. The latest generation clinker coolers have better clinker properties, has lower exit gas and clinker temperature.
4.6.4 More efficiency in grinding systems- in cement manufacturing grinding consumes the largest amount of energy. Indias cement production uses several grinding systems such as ball mills, ball mills with pre-grinder and VRM for clinker grinding. The newly installed plants have VRM for raw material and coal grinding and VRM ball mill with HPGR used for cement grinding which has taken up to 50% of the cement manufacturing capacity. Grinding mill is selected in the basis of the moisture content and the material hardness where VRM consumes less energy as its known for combined drying and grinding of the raw materials and coal.
External circulation system for material, latest generation classifier, adjustable louvre ring and modification of mill body are some examples of which are used to improve energy efficiency. VRM is widely known option for raw material and coal grinding and clinker grinding while closed circuit ball mill with high efficiency separator is used the most for common type of clinker grinding system.
Vertical Roller Mills (VRM) easy to use and less auxiliary equipment which in return reduce the maintenance cost. More over 6-10kWh/MT cement of electricity can be saved while 7-12kg CO2/MT is reduced.
Cost of installation varies for different grinding requirements however the vertical roller mill costs 2.3-2.5% more than the cost of installation of ball mill with closed circuit.(Confederation of Indian Industry, 2013)
Process fans among others the second largest energy consumers in cement industry. Like other cement industries in the world India also tried to increase energy efficiency and reduce operating cost by upgrading process fans. The modern process fans are capable of higher energy efficiency, low material build up, better speed control, higher wear resistance, low vibration and operation stability is fairly high. Process fans such as pre heater fans, coal mill fans, raw mill fans and cooler fans consume more than 40% of the total electrical energy.
The chart above shows the level of efficiency on different type of process fans. An appropriate speed control mechanism would be able to provide optimum energy efficiency when its worked with the right process fan. By monitoring the performance of the existing fans and replacing them when it needs replacement will improve energy efficiency.
184.108.40.206 Centrifugal compressorscan be used for lower energy consumption compared to screw compressor. As the demand for compressed air has been increased it is beneficial include a centrifugal compressor to achieve the lowest specific energy consumption.
220.127.116.11 Use of VFD for capacity control has higher operating range and reduced harmonics. Installation of VFD in a compressor can result in constant pressure and zero unloading which can result in power reduction.
18.104.22.168 Wobbler screen for crusher can ensure the undersized material from going into crusher avoiding the mixture of excessive fine material. They are known to run with moisture content of less than 5% and reduction of 0.5kWh/mt specific energy consumption.
4.7.1 Wind poweris of main renewable energy source which is used around India and has the ability of power transmission through national electricity and banking, known as keeping power for the later use of the grid which can help by higher benefits.
4.7.5 Solar thermal can be used for hot water generation and vapour absorption machines. This process can be used to produce cement with no carbon dioxide emissions. Solar thermal energy is used to heat limestone while assist in electrolysis producing a different chemical reaction producing zero carbon dioxide by product.
The report focuses on the energy and material efficiency in the cement sector India. Cement production in India has improved from where it has started by adapting to new technologies and working towards the carbon footprint. By using new technologies, harmful gases can be reduced in the cement industry. Out of many cement plants in India only a few has invested into new technologies to increase their production more efficient way at low cost.
HENDRIKS, C.A., WORRELL, E., DE JAGER, D., BLOK, K. and RIEMER, P., 1998. Emission reduction of greenhouse gases from the cement industry, Proceedings of the fourth international conference on greenhouse gas control technologies 1998, pp. 939-944.
Energy regards the power derived from a fuel source such as electricity or gas that can do work such as provide light or heat. Energy sources can be non-renewable such as fossil fuels or nuclear, or renewable such as solar, wind, hydro or geothermal. Renewable energies are also known as green energy with reference to the environmental benefits they provide.
Copyright 2003 - 2021 - All Answers Ltd is a company registered in England and Wales. Company Registration No: 4964706. VAT Registration No: 842417633. Registered Data Controller No: Z1821391. Registered office: Venture House, Cross Street, Arnold, Nottingham, Nottinghamshire, NG5 7PJ.
cement production - efficient and cost-effective cement works
The costs of heat and electricity are major factors in the production of cement. The powerful electric drives in mills and rotary furnaces also create a huge demand for reactive power. To reduce the costs of the reactive power purchased and comply with the connection requirements of the grid operator, appropriate compensation systems are almost indispensable. The use of speed-controlled drives reduces demand for electric power. As a result, harmonics may place strain on the grid. Appropriately designed filter systems help to retain the line voltage quality and comply with the requirements for connecting to the grid. For special cement, manufacturers also use electric arc furnaces, the voltage of which requires optimum control to prevent line perturbation and to keep the smelting process stable.
Reinhausen helps to optimize your cement production. MR on-load tap-changers regulate the step-up transformers, which supply your drives with the right voltage, with the maximum reliability you are accustomed to. Our vacuum on-load tap-changers perform 300,000 and more tap changes without maintenance. They also undertake the high number of tap-change operations needed for optimum control of electric arc furnaces. Reinhausen Power Quality helps you keep control of reactive power and grid disturbances: We analyze your requirements and provide compensation systems for reactive power along with tailored, high-precision filter systems for harmonics. And our global service team is of course always on hand.
production - ciment qubec
Cement is a fine powder that, when mixed with aggregates, sand and water, becomes concrete, the most popular construction material in the world. Cement, a basic material in construction, is found everywhere.
At Ciment Quebec Inc. (CQI), we are dedicated to making the best cement. This comes through the skills of our employees and the quality of our raw materials and equipment. Our Synergiaproduction process requires 30% less energy and generates up to 10% fewer harmful emissions during production than any other cementavailable in the market. Given this, we are able to produce eco-efficient, high-quality cement.
Limestone and other raw materials used in producing cement are extracted. At Ciment Quebec Inc., the main quarry is adjacent to the cement plant and provides more than 90% of the raw materials used. This way, materials do not have to travel over great distances. This reduces transportation-related greenhouse gas emissions.Regular sampling of the limestone during each phase of quarry operations enables CQIto have a clear understanding of the chemical composition of the material to optimize the limestone extraction through drilling and blasting operations.
The material is passed through a continuous analyzer advanced neutron-generation technologya technique that is much safer than the traditional isotope sources of nuclear isotopes generally used in traditional continuous analyzers. The stone is chemically analyzed on a continuous, real-time basis, which allows precisedosage of high and low calcium carbonate content stone as required by the standards.
This mix is then improved using a reclaiming scrapper, which is a giant spreading system that samples materials and forms a highly homogeneous mixture. Other samples are taken immediately to be analyzed in the laboratory.
Roller Crusher (H)
The mix of stones and other components is pulverized using the roller crusher, which results in a fine stone powder called raw meal. The heat recovered from the pre-heating tower is used to dry the raw meal and to extract the material outside the crusher.
Dust Removal (K-P-V)
Some 50 dust removers are installed strategically throughout the plant. The dust is recovered and re-used in the production process. All dustcollectors have leak detectors and other instruments that allow control room operators to constantly monitor operations. An alarm informs operators in the event of malfunction. The equipment is quickly identified and repaired. As for all other machines in the process, the control system enables process engineers to access data and trend graphs related to operation settings and dust removers during the previous days and weeks.
At the pre-heating tower, a series of cyclones stacked on each other transfer the energy between the hot gas and the raw meal. In under 30 seconds, the raw meal heats up from 90C to 900C, and calcination occurs during this short phase in the extended calcining furnace, where more than 60% of total heat energy is introducedin the process.
To reduce its carbon footprint and the use of these fuels, CQI added a solid fuel reactor known as an Eco-Furnace. Through the hot gases produced from the remains in the cooking circuit, this reactor burns various solid materials, such as used tires. The heat generated through combustion in the reactor is introduced into the cooking circuit, thereby reducing the use of traditional fossil fuels.
As a pioneer in the cement industry,the company was the second in the world to acquire this type of equipment in 2005. Only six were in operation internationally in 2012. Subsequently, CQI has reduced its use of conventional fuels by converting materials that would otherwise end up in landfills into an alternative. Additionnally, our process conserves from dry material disposal sites and helps to reduce the environmental impact of industrial waste.
Waste Material Recycling Centre
With the great success of the Eco-Furnace, CQI has continued developing its alternative fuels by making major investments to adapt the process for using waste materials and to equip its facilities for receiving, processing, storing dosing, and combusting other non-recyclable materials that would otherwise end up in landfills.These facilities are grouped together under the name Waste Material Recycling Centre.
Here, wood, paper, cardboard and plastic waste (that are not kept by redemption centres) are processed. By transforming those products into a fuel format that has the power to fully heat the pyro-processing requirements, these materials further reduce the cement plants dependency on fossil fuels.
The Waste Material Recycling Centre includes a second line of preparation, which primarily processes post-construction asphalt shingles and treated wood pieces like old railway ties, and electric or telephone poles.
Theseinstallations made the Saint-Basile cement plantot the forefront ofNorth America cement plants in the field of alternative fuels. Not only does the company find an advantage at reducing its heat energy load, it also significantly reduces its carbon footprint. In fact, the combustion of these alternative materials produces fewer greenhouse gases and other pollutants than traditional fossil fuels, providing the company with an effective tool to help meet the targets for reduced emissions imposed by the cap-and-trade system put in place by the Quebec government.
After calcination during the preheating step, the hot raw meal is put into the rotary kiln tomelt at a temperature around 1450C, thanks to a powerful multi-fuel burner of the latest technology. At this step (liquid phase), the different oxides (lime, magnesium, aluminium, sulphur, iron, etc.) that made up the raw materialrecombine intoa crystallographic structure different from the original one. The new material is then quickly cooled to achieve optimal crystal formation to produce very-high-quality cements.
CQIs rotary kiln, 4.9m diameter and 42.7m long, has one of the smallest length/diameter ratios in the world. With its plants ultra-efficient pre-heating tower, there is no need for a large oven to produce the heat required for making the clinker. This way, energy losses are also prevented.
Clinker Cooler (T)
The molten clinker is quickly cooled in a cooler. The hot gases generated at this stage in the clinker cooler are recovered and re-used in the pyro-processing circuit, which, in turn, recovers heat, thereby improving the circuits energy efficiency.
The clinker is grounded in a series of steel bars rotary mills, and is mixed with the gypsum, limestone and other cementitous materials based on the recipe of the different cement products that we produce. More samples are taken at this step by the laboratory. All cement mills are equipped with coolers to lower the temperature of the cement, thus helping the cement producer reach the temperatures required on the different sites that it serves.
Cement Silos and Transportation
Upon leaving the mills, the cement is pneumatically transported to silos where it is stored before being delivered in bags, semi-bulk, or bulk. It can be transported by truck, train or boat. St-Basile Transport, a subsidiary in charge of the Transportation Division, takes care of planning, and manages the logistics of shipping the cement.With a large fleet of tanker-trucks and experienced employees who focus on client delivery date requirements, St-Basile Transport on a daily basis strengthens the tie between CQI and its clients.
To ensure an adequate level of traceability of the delivered products, cement samples are taken upon loading, and specifically identified with this load. These samples are stored for future reference, as needed, ensuring that the cement was delivered in compliance with the quality standards.
The Ministre du Dveloppement durable, de lEnvironnement et de la Lutte contre les changements climatiques (MDDELCC) regulates air quality. Its regulations define air-quality criteria to protect human health, and minimize disturbances, as well as the effects on the ecosystem. Having the latest technology, CQI completely complies with this regulation.
At the chimney of the cement plant, a Fourier transform infrared spectrometer (FTIR) constantly takes measurements and analyzes air emissions in real time. This information is sent to control room computers.If the measurements exceed programmed regulatory settings, alarms notify control room personnel so that the situation can be quickly corrected.
In addition to the constant and precise monitoring of the chimney via this device, independent laboratories take samples on an annual basis to provide in situ characterizations of the chimney emissions.Independent sampling allows CQI to continuously corroborate internal information collected from our process and ensures compliance with the MDDELCCs needs regarding the Industrial Waste Registry (IWR).
The following substances are analyzed: oxygen (O), carbon dioxide (CO2), carbon monoxide (CO), hydrochloric acid (HCl), nitrogen oxide (NOx), sulfur dioxide (SO2), fine particles (PM2.5), and measurements related to dioxins and furans.
The IWR regulations also require that a destruction test is carried out every year.Toperform this test, CQIintroduces into its pyroprocess a precise volume of a gaseous compound called SF6, which is classified as the third most difficult compound to be destroyed by heat from a list of more than 300 compounds.Since there is no SF6 concentration in our raw materials or in our fuels, if the independent laboratory that conducts the destruction test measures a trace of SF6 in the chimney emissions, then it is easy to determine the destructive efficiency of this compound through the process.
At Ciment Quebec Inc. we are committed to manufacture the best cements. We achieve this through the skills of our dedicated employees, the high quality of the materials we select and with the technology we use for manufacturing. Our cement manufacturing process Synergia requires 30 % less energy and generates up to 10 % less polluting emissions than other cements available on the market. This enables us to produce eco-efficient cements of the highest quality.