Concrete
Pyroprocessing and Kiln Operation
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2 years agoon
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Dr SB Hegde, Professor, Jain University, Bangalore, talks about pyroprocessing and the role of preheater, rotary kiln and clinker cooler in the cement manufacturing process. In the concluding part of the two-part series, we will learn more about the various factors aiding pyroprocessing.
False Air in Pyro Processing
India is the second largest cement producer in the world in terms of cement capacity. Therefore, it is deciphered that the amount of energy being consumed in cement production process and its wastage attributed to non-availability of proper technology to plug the leakages.
There are several research papers/case studies discussing the effect of different factors on energy consumption in cement manufacturing and are well documented. There are some studies that discuss this issue with the help of mathematical models. However, all studies reveal the fact that the ‘false air’ may be one of the factors for higher energy consumption in cement plants. Further, based on the several studies in the field of operational audit, it can be concluded that production level can be improved and energy consumption reduced by reduction of ‘false air’.
False air is any unwanted air entering into the process system. The exact amount of false air is difficult to measure. However, an indicator of false air can be increase of per cent of oxygen between two points (usable for gas streams containing less than 21 per cent of oxygen). Due to unwanted air, the power consumption increases and the system’s temperature decreases. Therefore, to maintain the same temperature fuel consumption has to be increased.

Impact of False Air in a Cement Plant
• Increase of power consumption
• Increase the fuel consumption
• Unstable operation
• Reduction in productivity
• Higher wear of fans
False Air Ingress Points
In cement plants, generally false air intrudes in the kiln section through the kiln outlet, inlet seal, TAD slide gate, inspection doors and flap box. Similarly, in mill section false air intrudes through rotary feeder at mill inlet, mill body, mill door, flaps, expansion joints, holes of ducts and tie rod entry point. In the power sector, as margin is very less, cost- effectiveness plays an important role. Generally false air intrudes in the CPP section through air pre-heater casing, boiler main door, fan casing, inspection doors, ESP main doors, ESP hopper doors, expansion bellows and ducts. Similarly, in the GPP section false air intrudes through main holes, hammering, bellows, rotary air locks, damper casing, expansion bellow, etc.

Checking of Heat balance
Heat balance on a kiln can offer extremely useful information on the thermal performance of the system. Heat balance shows where or how the fuel heat is consumed based on the simple principle of input = output.
Unnecessary energy losses can be easily detected, the principle of heat balance may be easily transferred to another system such as preheater, cooler and drying system. Various reasons or circumstances may cause a need for a heat balance measurement. The following situations may justify a heat balance:
- Performance test,
- Recoding of kiln performance before/after a modification,
- Unusually high heat consumption or abnormal kiln operational data,
- Kiln optimisation endeavours.
Although the specific heat consumption proper could also be determined by measuring nothing but fuel heat and clinker production, a complete heat balance does offer considerably more information and security.
The consistency of the measured data is proved much better, and the balance shows clearly where the heat is consumed. A heat balance is obviously a very efficient tool assessment of thermal efficiency. A heat balance does not only mean calculation of heat balance items.

Kiln Operation Problems Using Pet Coke
- The consequence of using pet coke is dusty conditions and a kiln inlet ring. Even though there is no CO (carbon monoxide) in the kiln inlet, the large amount of SO3 introduced by the pet coke may not be properly balanced by alkalis (Na2O and K2O) in the kiln feed. This will result in a high SO3 re-circulation and a reduction of the liquid phase surface tension and viscosity. This will produce poor clinker nodulation and a corresponding increase in the dust load in the kiln and rings near the kiln inlet.
- The possible solutions are:
- Ensure that the high SO3 input is balanced with the appropriate percentage of alkalis.
- Optimise the burnability of the raw meal in order to reduce the burning zone temperature.
- Optimise the flame shape to reduce the length of the burning zone.
- Increase the O2 at the kiln inlet even more to ensure enough oxygen is present to remove the increased amount of alkali sulphates from the kiln.
If chloride levels are high in the raw materials this can react preferentially with the alkalis in the bottom cyclones, reducing the percentage of alkalis available to remove SO3 from the kiln. In this case the only practical solution is to try and reduce the chloride input.
Pet coke sometimes needs more O2 at the kiln inlet than required. It is common in some plants to have to run with 6-8 per cent O2 at the kiln inlet to keep SO3 recirculation down to an acceptable level. Remember that just having a small excess of O2 in the kiln inlet (sufficient to ensure zero CO) may not be enough to control the high sulphur input from pet coke.
2K2O + 2SO2 + O2 = 2K2SO4
2CaO + 2SO2 +O2 = 2CaSO4
The molecular weight s is
2SO2 = 128
O2 = 32
Therefore, every 4 tonne of SO2 needs 1 tonne of O2 to be converted to SO4-2, no matter if there are sufficient alkalis or not. Calculate the percent of O2 required at the kiln inlet from the total input of SO2 from pet coke and the gas flow rate at the kiln inlet.

Burning softer (i.e., lower litre weight) is a good idea because it uses less fuel and lowers the sulphur input. Softer burning will reduce the sulphur volatilisation in the burning zone (ensuring oxidising conditions in the burning zone is critical since CaSO4 is more susceptible to thermal decomposition under slightly reducing conditions than alkali sulphates.).
Traditionally it is known that an excess SO3 content of some 300-700 gm per 100 kg clinker can be tolerated in the kiln system. Lower limit will be valid for hard to burn raw materials while the upper one refers to easy burnable raw meals. Apart from adjustment of the sulphur/alkali ratio it is possible by operational means to substantially reduce the sulphur evaporation in the burning zone. One can consume 1000 gm SO3 per 100 kg clinker by the following changes in burning operation.
- High Oxygen – levels in the kiln (around 5 per cent O2)
- High Flame Momentum
- Short residence time in the burning zone
- Improve chemical burnability
- Finer grinding of raw mix and pet coke
Significance of Liquid Content in Clinker
Liquid content of clinker is the fraction of the kiln feed that melts between the upper transition and burning zone. The liquid content has a critical role in clinker nodulisation and clinker phase development and properties. In the absence of liquid, the conversion of C2S and free lime to C3S would be almost impossible in the kiln.
Plant chemists and CCR operators are usually more concerned with the amount of liquid rather than with the rheological properties of the liquid. The latter is more important during clinkering reactions than the former.
Amount of liquid Content
The raw mix consists of only 4 oxides, i.e., CaO, SiO2, Al2O3 and Fe2O3, it would start melting at 1,338 degree C, the so-called eutectic temperature for the system C-S-A-F.
Industrial raw mixes contain impurities such as MgO, Na2O, K2O and SO3. At certain concentrations, these impurities reduce the eutectic temperature of the system to 1,280 degree C, thus promoting clinker formation. These oxides act as fluxes in the kiln, forming liquid as far up in the calcining zone.
Liquid percentage at 1,450 C=3XA+2.25XF+MgO+K2O+Na2O+SO3 (MgO<2).
For most commercial clinkers, the amount of liquid content is in the range of 26-29.5 per cent. Higher values can be damaging to most refractory bricks in the absence of stable coating. As the brick is infiltrated and saturated with liquid, its elastic modulus increases and so does its tendency to spall off.
The tendency to coating formation or the coataibility of clinker increases with the amount of liquid. However, more coating does not necessarily mean better coating. Coating refractoriness, texture and stability are by far more important than the amount of coating deposited on the lining.
Significance of liquid content
The most important clinker phase is C3S (alite) which requires the presence of liquid for its formation. In the absence of liquid, alite formation is extremely slow and it would render clinkering impossible. This fact also explains why alite is formed essentially in the burning zone, where the amount of liquid is at a maximum.
To understand why alite formation requires
liquid content, one must first understand the alite formation mechanism:
- C2S and free CaO dissolves in the clinker melt.
- Calcium ions migrate towards C2S through chemical diffusion
- C3S is formed and crystallised out of the liquid.
Without liquid phase the diffusion of Ca ions towards C2S would be extremely slow, and that of C2S almost impossible at clinkering temperature. It is important to mention that Na2O and K2O decrease the mobility of Ca ions, whereas MgO and sulphates considerably increase it. That is why addition of gypsum in the raw mix promotes alite formation.
Properties of liquid phase Viscosity
Temperature has the most pronounced effect on liquid phase viscosity. Low viscosity liquid infiltrates the refractory lining faster, leading to its premature failure. MgO, alkali sulphates, fluorides and chlorides also reduce liquid phase viscosity.
Free alkali and phosphorous increase liquid phase viscosity, but this effect is offset by MgO and SO3. Only clinkers with S/A ratio lower than 0.83, low in MgO, would experience the negative effects of high liquid viscosity.
The liquid content viscosity increases linearly with A/F ratio. For a given burning temperature, high C3A clinkers tend to nodulise better than low C3A clinkers. Moreover, the liquid phase is considerably less damaging to the refractory lining when the liquid is viscous.
Another important property of the liquid phase is its surface tension, or its ability to ‘wet’ the lining. The surface tension has a direct impact on clinker fineness, coating adherence to the lining and clinker quality.
High surface tension values would favour nodule formation and liquid penetration through pores of the nodules. The resulting clinker contains less dust (fraction below 5 or 10 mm) and lower free lime content. A liquid phase with high surface tension has less tendency to adhere to the brick surface, therefore, reducing clinker coatibility or adherence to the lining.
Alkali, MgO and SO3 reduce liquid surface tension. So does temperature. Sulphur and potassium have the strongest effects, followed by sodium and magnesium. Therefore, MgO, SO3 and K2O to a certain concentration, are good coating promoters.
Unfortunately, the liquid properties that induce C3S formation are detrimental to the refractory lining and to clinker nodulisation.
Although the amount of liquid phase in the burning zones of the kiln is important to clinker formation and brick performance, the rheological properties of the melt are even more important. The rheological properties of the clinker melt control parameters such as clinker mineral formation, clinker coatability, clinker fineness, cement strength and refractory depth of infiltration.
It is then very important to keep fuel, raw material properties and flame temperature as steady as possible. Whenever introducing drastic changes in the raw material or fuel properties, the refractory lining must be changed accordingly to meet the differences in clinker coatability and burnability.
Material Balance of a Pyro Processing in Clinker Production
The following diagram illustrates an example of the mass flows in a cement plant and the mass balance of a kiln system from raw meal (RM) to clinker.
Figure 1: Schematic diagram of material and dust flows in a cement plant
The reporting of CO2 emissions from the calcination of raw materials depends on the principle choice of the method for determining the mass balance: from the input side (raw meal consumption).
Accordingly, we need to consider the reporting of the mass flows bypass dust, cement
kiln dust leaving the kiln system (and crossing the red boundary in the diagram) and additional raw materials), which are not part of the normal kiln feed, as follows:
Simple input method and detailed input method: The actual amount of raw meal consumed for clinker production can be determined by weighing the kiln feed and subtracting the dust return.
- Bypass dust leaving the kiln system is accounted for in the amount of raw meal consumed. Additional calculations may be required if the bypass dust is only partially calcined. This is implemented only in the detailed input method:
- CKD recycling remains within the mass balance and therefore does not need additional reporting.
- CKD leaving the kiln system (and crossing the red boundary in the diagram) needs to be quantified and requires additional reporting in the input methods.
- Additional raw materials (ARM), which are not part of the kiln feed are not accounted for by the amount of raw meal consumed. Thus, they require additional reporting in the input methods. However, the necessary calculations are only implemented in the detailed input method. The simple input method (A1) should therefore not be used if ARM is relevant for the complete reporting of the CO2 emissions.
Simple output method and detailed output method: The amount of clinker production can be determined from calculating the clinker mass balance or by direct weighing.
- Bypass dust leaving the kiln system requires separate reporting:
- CKD recycling remains within the mass balance. Thus, it does not need additional reporting.
- The mass flow of CKD leaving the kiln system (and crossing the red boundary in the diagram) needs to be accounted for additionally.
- Additional raw materials (ARM) do not need to be accounted for additionally in the output methods, which are based on the clinker production.
Conclusions
Pyro-processing in a cement plant comprises a preheater, rotary kiln and clinker cooler. Pyro-processing section is considered to be the heart of a cement plant as actual cement clinker production takes place in kilns.
The size of a cement plant is determined based on the pyro-processing section and the sizes of all other equipment are determined to match pyro-processing. Cyclones are basic units in a preheater system. Pressure drop and change of temperature of gas across each stage determines the efficiency of cyclones.
Introduction of Low Pressure drop (LP) cyclones has brought the pressure drop across each stage to around 50 mm WG from around 150 mm WG in conventional cyclones. This has resulted in more and more plants adopting 5 or 6 stages of preheater.
A typical 6 stage preheater with LP cyclones will have a preheater exhaust gas temperature of around 250°C and draught of around 500 mm WG. This in turn led to decrease in preheater fan
power consumption.
The reduced temperatures at preheater exhaust contribute to environmental improvement. Cyclone separators are used in preheaters on cement plants to separate the raw material for gases. Very tall preheater means more power is required to operate the plant.
It is always desired for a minimum preheater height to operate the plant economically. Due to the preheater arrangement and layout design, cyclones decide the height of the preheater. Pressure drop-in cyclones plays an important role in determining the cost of operation of a cyclone separator. High pressure drop means more power required to operate the cyclone.

ABOUT THE AUTHOR
Dr SB Hegde is currently a Professor at Jain University, Bangalore, Karnataka, and a Visiting Professor at Pennsylvania State University, United States of America. He has more than 30 years of experience in cement manufacturing both in India and abroad. He has occupied the ‘Leadership positions’ in reputed major cement companies both in India and overseas. He is also a recipient of ‘Global Visionary Award’ instituted by Gujarat Chambers of Commerce and Industry, Ahmedabad in 2020.
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Efficient bulk material handling has always been critical for seamless production, cost reduction and environmental compliance. Kanika Mathur delves into advanced automation, smart sensors and sustainable transport solutions that are key to overcoming challenges.
The cement industry is a cornerstone of infrastructure development, contributing significantly to economic growth. However, cement production involves the handling and transportation of vast quantities of raw materials such as limestone, clay, iron ore, fly ash and gypsum, as well as the final product—cement itself. Efficient bulk material handling (BMH) systems are crucial in ensuring uninterrupted production, reducing operational costs, minimising material wastage and improving overall efficiency.
In an industry where material losses, dust emissions, and energy consumption are major concerns, advancements in bulk material handling technology are playing a vital role in optimising operations. Automated and energy-efficient bulk handling solutions, such as pneumatic conveying systems, belt conveyors and stacker-reclaimer systems, are transforming the way cement plants manage their raw materials and finished products. This article explores the key aspects of bulk material handling in the cement industry, the latest technological advancements, and the challenges and opportunities in this space.
Importance of bulk material handling
Cement manufacturing requires the continuous movement of raw materials from mines and quarries to processing plants, followed by the transportation of the finished product to storage facilities and distribution networks. Bulk material handling systems ensure that this process runs smoothly, reducing downtime and enhancing productivity.
According to the Global Cement Report (2023), inefficient material handling contributes to 5 – 10 per cent of total cement production losses in India. Additionally, poor handling practices lead to high levels of dust pollution, which is a significant environmental and health concern. With cement production in India expected to reach 500 million metric tonnes by 2025, the demand for advanced and automated material handling systems is increasing rapidly.
Jacob Jose, CEO and Managing Director, Methods India, says, “With our advanced pipe conveyors, downhill conveyors and cross-country conveyors, we have revolutionised the way cement plants transport raw materials. Our technology helps reduce operational costs, minimise environmental impact and improve energy efficiency. Over the years, we have observed a positive impact in the industry, particularly with the growing adoption of pipe conveyors and cross-country conveyors, which have proven to be more efficient and environmentally friendly alternatives to traditional transport methods.”
Key bulk material handling technologies
1. Belt conveyors: The workhorse of cement plants
Belt conveyors are one of the most widely used bulk material handling solutions in the cement industry. They transport raw materials, clinker and finished cement over long distances within the plant and to storage facilities. Modern high-capacity belt conveyors can handle loads exceeding 10,000 tonnes per hour, significantly improving efficiency.
- Advantages: High efficiency, low operational costs, and reduced manual intervention.
- Challenges: Belt wear and tear, spillage, and maintenance requirements.
- Technological advancement: The introduction of heat-resistant and fire-retardant conveyor belts has improved durability, while sensor-based predictive maintenance systems help detect belt failures before they occur.
2. Stacker and reclaimer systems: Optimising storage and retrieval
Stackers and reclaimers are essential for managing bulk raw materials in cement plants. Stackers pile materials such as limestone, coal, and gypsum, while reclaimers retrieve them for processing. These systems ensure homogeneous blending, reducing material variability and enhancing cement quality.
- Latest innovation: Automated stacker and reclaimer systems with AI-driven optimisation help maximise storage space and minimise
retrieval time. - Efficiency gains: Newer stacker-reclaimer designs allow for material recovery rates of over 90 per cent, reducing wastage and ensuring a steady feed to the production line.
3. Pneumatic conveying systems: Dust-free material transfer
Pneumatic conveying systems use air pressure or vacuum systems to move powdered and granular materials such as fly ash, cement and kiln dust through pipelines. They are particularly useful in reducing dust emissions and preventing material contamination.
- Advantages: Dust-free operation, reduced environmental impact, and minimal maintenance.
- Industry adoption: Many Indian cement plants are shifting from mechanical conveyors to high-pressure pneumatic conveying systems to comply with pollution control regulations set by the Central Pollution Control Board (CPCB).
4. Screw conveyors and bucket elevators: Compact and versatile solutions
- Screw conveyors: Used for short-distance material movement, particularly for handling fine and powdered materials such as cement, gypsum, and pulverised coal.
- Bucket elevators: Ideal for vertical material transport, commonly used for lifting raw meal, cement, and clinker to storage silos.
- Technological upgrades: The introduction of wear-resistant alloy buckets and variable-speed drives has enhanced the reliability and efficiency of these systems.
Challenges in bulk material handling
Despite significant advancements, several challenges continue to hinder bulk material handling efficiency in cement plants:
1. Material spillage and dust emissions
Material spillage and dust emissions pose environmental, health, and financial challenges. Uncontrolled dust emissions from conveyors, transfer points, and storage facilities not only violate regulatory norms but also lead to material losses. Studies show that up to three per cent of bulk materials are lost due to improper handling in Indian cement plants.
- Solution: Enclosed conveyors, dust suppression systems, and bag filters help reduce dust pollution.
2. High energy consumption
Bulk material handling systems consume a significant amount of energy, especially in large cement plants where materials need to be transported over long distances. According to a CII (Confederation of Indian Industry) report (2023), energy costs account for nearly 40 per cent of total production expenses in cement manufacturing.
- Solution: Energy-efficient conveyor motors, regenerative braking systems, and smart automation can help reduce power consumption.
3. Wear and tear of equipment
Continuous exposure to abrasive materials like limestone and clinker leads to significant wear and tear in bulk material handling equipment, increasing maintenance costs and downtime.
- Solution: The use of wear-resistant liners, ceramic-coated conveyor belts, and automated lubrication systems extends equipment life and reduces maintenance downtime.
4. Logistics and transportation bottlenecks
Moving bulk materials from cement plants to distribution centers requires an efficient logistics network. Rail and road congestion, inadequate infrastructure, and high transportation costs often result in delays and increased operational expenses.
- Solution: Integrated bulk terminals and automated dispatch systems improve supply chain efficiency. The Indian government’s push for multi-modal logistics parks (MMLPs) is expected to enhance cement transportation efficiency.
Indrendra Singh Raghuwanshi, Sales Head – Cement Division, ATS Conveyors, says, “Ensuring that our systems handle diverse alternative fuels reliably is at the core of our engineering approach. Alternative fuels, such as biomass, MSW, RDF and industrial waste vary significantly in terms of composition, size, moisture content, and combustibility. All our systems are designed with flexibility and robustness to meet the unique challenges posed by these fuels while maintaining operational efficiency and safety. Also, before deployment to site, we conduct extensive testing for our equipment to ensure that they can reliably handle alternative fuels under a variety of conditions. This includes testing different fuel types, moisture levels, and feeding rates to identify any potential challenges. Our systems are then fine-tuned during the commissioning phase to ensure optimal performance in real-world conditions.”
The future is automation and digitalisation
The future of bulk material handling in the cement industry lies in automation, artificial intelligence (AI), and digital twin technologies. Leading cement manufacturers are investing in IoT-enabled bulk handling systems that provide real-time monitoring, predictive maintenance, and AI-based process optimisation.
1. Smart sensors and predictive maintenance
AI-powered sensors are now being integrated into conveyors and stackers to detect early signs of wear and tear, enabling proactive maintenance and reducing unplanned downtime.
Nishith Kundar, Co-Managing Partner, Cemtech Engineering Solutions, says, “One of our latest advancements is the introduction of drone inspection technology. Since silos are confined spaces, it is often difficult to assess their internal condition, particularly at the top. We have incorporated drone inspections for both pre-cleaning and post-cleaning assessments. Pre-cleaning drone inspections help us analyse the extent of material buildup, while post-cleaning inspections ensure that the silo has been thoroughly cleaned. This technology is also applicable to pre-heaters, allowing us to monitor internal conditions in confined spaces. By leveraging drone technology, we provide precise and efficient cleaning services, improving safety and operational efficiency.”
2. Digital twin technology
Digital twin models create a virtual replica of bulk handling systems, allowing operators to simulate various scenarios and optimise material flow before implementing changes in real time.
3. Automated Guided Vehicles (AGVs) and robotics
The adoption of AGVs and robotic material handling systems is gaining traction in cement plants for automated raw material transport, warehouse management, and truck loading/unloading.
Gaurav Gautam, Business Unit Head,
Beumer Group, says, “A major recent focus has been integrating digital monitoring tools into our equipment. These tools include condition monitoring sensors that track temperature variations, vibrations and operational anomalies in real-time. By capturing this data, plant operators can take proactive actions when conditions start deviating from normal parameters. This approach prevents sudden breakdowns and, in the long term, enhances the durability and reliability of the equipment.”
“Moving forward, digitalisation will play a key role in tackling wear and tear challenges. By increasing the number of data capture points and applying advanced analytics tools, we can gain deeper insights into equipment health and performance, ensuring a more efficient and predictive maintenance strategy,” he adds.
Conclusion
Efficient bulk material handling is the backbone of cement manufacturing, ensuring a seamless flow of raw materials and finished products while minimising environmental impact and operational costs. As India’s cement industry moves towards higher production capacities and stricter environmental norms, investing in advanced, automated and energy-efficient bulk handling solutions will be key to maintaining competitiveness.
By embracing smart technologies, automation and sustainable handling practices, cement manufacturers can enhance productivity, reduce material losses, and contribute to a greener and more efficient future for the industry.

Accelerating sustainability in the cement industry through alternative fuels and raw materials is key to reducing carbon emissions, optimising resources, and advancing circular economy initiatives. As the industry moves towards a low-carbon future, ICR discusses these critical developments with industry experts.
The cement industry plays a crucial role in infrastructure development and economic growth. However, it is also one of the most carbon-intensive industries, responsible for nearly seven per cent of global CO2 emissions (IEA, 2023). The industry’s heavy reliance on fossil fuels such as coal and petroleum coke, combined with the high emissions from clinker production, has led to growing concerns over its environmental impact.
To address these challenges, cement manufacturers worldwide are increasingly adopting alternative fuels and raw materials (AFR) as part of their sustainability strategies. AFR not only helps in reducing carbon emissions but also supports waste management by utilising industrial by-products and municipal waste. By replacing conventional fuels and raw materials with more sustainable alternatives, the cement industry can significantly lower its environmental footprint while contributing to the circular economy.
Traditional cement manufacturing processes consume large amounts of natural resources, including limestone, clay, and fossil fuels. The production
of one tonne of cement generates approximately 0.9 tonnes of CO2, with the calcination of limestone contributing to 60 per cent of total emissions, while the burning of fossil fuels accounts for the remaining 40 per cent (GCCA, 2023). With global demand for cement expected to rise due to rapid urbanisation and infrastructure expansion, the urgency to adopt low-carbon alternatives has never been greater.
A study by the Global Cement and Concrete Association (GCCA, 2023) highlights that to achieve net-zero emissions by 2050, the cement industry must reduce its carbon footprint by at least 40 per cent by 2030. Alternative fuels and raw materials present a viable pathway to achieving this goal by replacing traditional carbon-intensive inputs with more sustainable and energy-efficient options.
Reducing fossil fuel dependency in cement kilns
Cement kilns operate at extremely high temperatures—often exceeding 1,400°C—making them highly suitable for the incineration of alternative fuels. These high temperatures ensure complete combustion, effectively neutralising pollutants and reducing waste disposal challenges. The most commonly used alternative fuels in cement manufacturing include:
Municipal Solid Waste (MSW) and Refuse-Derived Fuel (RDF)
Municipal solid waste, particularly its non-recyclable components, can be processed into refuse-derived fuel (RDF), which serves as a viable replacement for coal. RDF is composed of materials such as plastics, paper, textiles, and organic waste, which are processed to achieve a high calorific value.
In India, the use of RDF has increased by 12 per cent annually, driven by government initiatives like the Swachh Bharat Mission and the Central Pollution Control Board (CPCB) directives on waste-to-energy projects. Cement plants that integrate RDF in their fuel mix not only reduce reliance on fossil fuels but also contribute to municipal
waste management, preventing large-scale landfill accumulation.
Biomass and agricultural waste
India generates over 500 million tonnes of agricultural waste annually (NITI Aayog, 2022), a significant portion of which goes unutilised or is burned in open fields, contributing to severe air pollution. By leveraging biomass materials such as rice husks, sawdust, coconut shells, sugarcane bagasse, and groundnut shells, cement kilns can replace conventional fuels with carbon-neutral alternatives.
Biomass combustion releases only the CO2 absorbed by plants during their growth cycle, making it an environmentally friendly energy source. Moreover, cement plants using biomass benefit from reduced fuel costs and government incentives for sustainable energy adoption.
Tushar Khandhadia, General Manager – Production, Udaipur Cement Works, says, “Alternative fuels (such as biomass, waste-derived fuels or industrial by-products) often have lower energy content compared to traditional fuels like coal or pet coke. This means that more of the alternative fuel is required to achieve the same level of heat generation. As a result, more fuel needs to be burned, potentially increasing the overall heat consumption of the kiln.”
“Some alternative fuels have higher moisture content or volatile substances, requiring additional energy to evaporate the moisture or combust these volatile compounds. This can lead to a higher heat consumption during the combustion process,”he adds.
Scrap tires and rubber waste
Discarded rubber tires pose a significant waste disposal challenge, with millions accumulating in landfills each year. Cement kilns provide an ideal solution by using shredded tires as an alternative fuel, leveraging their high calorific value, which is comparable to coal. Studies indicate that each ton of scrap tires used in cement kilns can replace approximately 0.7 tonnes of coal, resulting in substantial CO2 emission reductions (CEMBUREAU, 2023).
Industrial and hazardous waste
Cement kilns are also used to incinerate industrial and hazardous waste, including solvents, paint sludge, petrochemical residues and pharmaceutical waste. The extreme temperatures and long residence times in kilns ensure complete combustion, preventing toxic emissions.
India’s Hazardous Waste Management Rules (2016) encourage industries to co-process their waste in cement plants rather than disposing of it in landfills, thus minimising environmental risks while supporting sustainable fuel alternatives.
S Sathish, Partner and National Sector Leader – Industrial Manufacturing, KPMG India, says, “Energy and fuel cost is one of the key costs for cement sector. While a lot of focus has been done on energy consumption optimisation, waste heat recovery areas, buying optimisation of coal and petcoke is a new area, which cement companies are focusing on. Having an AI-based model to optimise the buying cost of fuel, based on petcoke price trends, price trends of coal from different sources, both import and domestic, quality variation analysis of different sources, etc. is a best practice adopted by some leading players to optimise fuel buying. Exploration with green fuels and alternative fuel resources is another big area cement players are working on.”
AFR: A sustainable approach to clinker reduction
The production of clinker, the key ingredient in cement, is highly energy-intensive and generates a significant amount of CO2. By using alternative raw materials (ARMs), manufacturers can reduce their clinker factor, leading to lower emissions and improved resource efficiency.
While replacing fossil fuels like coal and pet coke with alternative fuels can help lower CO2 emissions in the cement industry, the overall reduction is often limited—typically ranging from 1–5 per cent in most cases, with a maximum potential of 18 per cent in select scenarios. The extent of reduction depends largely on the biogenic content of the alternative fuel source. Additionally, certain alternative fuels contain higher levels of sulphur, nitrogen, chlorine, heavy metals and other volatile compounds, which can lead to increased emissions of non-CO2 air pollutants. As a result, maintaining control over emissions—beyond just CO2, including SOX and NOX—has become a key focus. To mitigate these risks, ongoing investments have been necessary as the use of refuse-derived fuel (RDF) continues
to grow.
The most widely used ARMs in cement production include:
Fly ash and bottom ash
Fly ash, a by-product of coal-fired thermal power plants, has gained widespread adoption as a partial clinker substitute. India produces around 226 million tonnes of fly ash annually (CEA, 2023), a substantial portion of which can be utilised in cement production.
Fly ash not only reduces CO2 emissions but also enhances cement properties such as durability, workability, and resistance to sulfate attacks. The Bureau of Indian Standards (BIS) allows up to 35 per cent fly ash in Portland
Pozzolana Cement
(PPC), making it a key component of sustainable cement formulations.
Steel slag and granulated blast furnace slag (GBFS)
The steel industry generates approximately 25 million tonnes of slag annually (Ministry of Steel, 2023). Granulated Blast Furnace Slag (GBFS) is a valuable clinker substitute, with the potential to replace up to 60 per cent of clinker in cement production.
GBFS-based cement exhibits superior strength, durability, and resistance to harsh environmental conditions, making it a preferred choice for infrastructure projects, marine structures, and
road construction.
Olli Hänninen, Owner and Co-founder, Moviator Oy says “The key advantage of using slag today is its ability to reduce CO2 emissions. Cement production relies on four key oxides: calcium oxide, silicon oxide, aluminum oxide and iron oxide—all of which are present in slag. Since slag has already undergone thermal treatment, its use in cement manufacturing requires less energy. As a result, producing cement with slag generates lower CO2 emissions.”
Limestone calcined clay cement (LC3)
Limestone calcined clay cement (LC3) is an innovative low-carbon cement that reduces clinker content by 50 per cent, significantly lowering energy consumption and CO2 emissions. Research conducted by IIT Delhi and EPFL Switzerland suggests that LC3 cement has 25 per cent to 30 per cent lower CO2 emissions compared to Ordinary Portland Cement (OPC) while maintaining comparable strength and performance.
Challenges in large-scale AFR adoption
Despite the significant benefits of AFR, its widespread adoption in India remains limited, accounting for less than 5 per cent of total cement production, compared to 40 per cent in Germany and 60 per cent in the Netherlands (GCCA, 2023). Key challenges include:
Lack of infrastructure for waste collection, sorting, and processing.
Variability in AFR quality, leading to inconsistent combustion efficiency.
Regulatory hurdles in obtaining permits for hazardous waste co-processing.
Limited public awareness about the environmental benefits of AFR.
Strategies for enhancing AFR utilisation
To accelerate the adoption of AFR in India, cement manufacturers must focus on:
1. Developing pre-processing facilities: Establishing regional AFR hubs for waste segregation and processing.
2. Enhancing policy incentives: Government support through tax benefits, subsidies and carbon credits.
3. Industry collaboration: Partnerships between cement companies, municipalities and waste management firms.
4. Advanced emission monitoring: Implementing real-time air quality sensors to ensure compliance with environmental norms.
Andrey Korablin, Founder, SmartScrap, says, “One of the biggest challenges is the human factor. Unfortunately, in many industrial enterprises, people are resistant to change. This is not only because mid-level employees are reluctant to adapt but also due to a lack of proper motivation for using alternative raw materials. In many cases, alternative materials can initially lead to lower productivity or increased energy consumption.”
“These factors directly impact key performance indicators (KPIs) for employees. If using alternative raw materials negatively affects these KPIs, it can also reduce their salaries. Additionally, there is little incentive for employees to seek alternative solutions—if their initiative proves successful, they may receive no financial reward. However, if they make a mistake, they could be demotivated or even risk losing their jobs. This is why, at the top management level, it is crucial to create a system of motivation and a company culture that encourages change and innovation,”
he adds.
Conclusion
The integration of alternative fuels and raw materials is essential for the cement industry’s transition towards low-carbon and sustainable manufacturing practices. By replacing fossil fuels and traditional raw materials with eco-friendly alternatives, the industry can significantly reduce emissions, lower energy consumption, and contribute to a circular economy. With the right policies, technological advancements, and industry collaboration, AFR adoption in India can scale up, paving the way for a more sustainable and resilient cement sector.
– Kanika Mathur
Concrete
Innovative Strategies for Cost Optimisation
Published
2 hours agoon
March 11, 2025By
admin
S Sathish, Partner and National Sector Leader – Industrial Manufacturing, KPMG India, explores key levers across energy, logistics, and manpower to drive efficiency and resilience.
Over the last two quarters, margins of cement players are under pressure and some of the players have shown a 25 to 30 per cent reduction in their EBITDA. While the key reasons can be attributed to the external situation of rising material prices and constraints to increase cement price, all the players are quite actively looking at strategies to enhance the bottom line to stay prosperous. The need of the hour for cement players is to think of innovative cost optimisation practices. We will deep dive into optimisation strategies for three major cost heads in this article.
Optimisation opportunities
A: Energy and fuel cost is one of the key costs for cement sector. While a lot of focus has been done on energy consumption optimisation, waste heat recovery areas, buying optimisation of coal and petcoke is a new area, which cement companies are focusing on.
Identifying the right import supplier and source country combination can help in optimising the buying cost. We have seen that if this aspect is intelligently done can lead to an optimisation of 8 to 10 per cent in fuel costs. This would entail mapping the importers in India, quantities they import, companies they supply and deciding the right contracting strategy with the right ones.
Analysing the quality of different sources of coal such as Indonesian, South African, Middle Eastern, American, etc. and deciding the right fit for your organisation based on equipment capability can help in optimisation.
Having an AI-based model to optimise the buying cost of fuel, based on petcoke price trends, price trends of coal from different sources, both import and domestic, quality variation analysis of different sources, etc. is a best practice adopted by some leading players to optimise fuel buying.
Exploration with green fuels and alternative fuel resources is another big area cement players are working on.
B: Logistics cost is the next biggest cost driver in cement sector. While prima facie this cost appears to be driven more by demand requirement and market conditions, a sharper focus on drivers of spend will help in optimising this cost.
Many companies operate with a long tail of transporters for each lane to de-risk themselves from the cost of unavailability of trucks. However, the share of business gets split across multiple transporters leading to lesser bargaining power. Some companies operate based on three quote negotiations even today where the breakup of price is opaque to the buyers. Leading companies adopt zero-based costing methodologies / should be cost modelling to build up the should be costs and use that for negotiation coupled with share of business optimisation. AI is used by some of the companies here as well in deciding the right share of business based on supplier price and transporter performance scores.
Synergy leverage between outbound, inbound, primary and secondary logistics is another innovative way of optimisation. Traditionally inbound and secondary logistics is managed by procurement function and outbound and primary transport is managed by sales function. This structurally does not allow for optimisation of spend and we have seen that the same transporter manages between two different functions and in some cases even with different rates for the same distance. Structured negotiation with the total spend share for the transporter can give substantial optimisation. Many companies have changed the logistics organisation structure between inbound and outbound logistics under a common reporting structure.
Load consolidations and right carrier/mode mix optimisation is a big lever. Based on analytics of load in a particular direction and the vehicle type used provides one with an option of increasing the vehicle capacity. An increased vehicle capacity can reduce the number of trips and at the same time reduces the logistics cost per ton. Loadability is often not measured which if optimised can help in reducing the costs. Evaluating the
right logistics mode in terms of road, rail and sea transport based on destination is another
lever used by different industries. Some of the leading cement players are exploring waterways to become more sustainable.
C: Manpower costs is one of the next biggest costs in cement sector. We can look at key strategies for contract manpower costs and white collar costs.
Typically contract manpower costs are a big contributor to manpower costs. Companies adopt the piece rate model or man-day rate model in areas such as packing where a daily output is involved. While a piece rate model may appear optimal, many companies don’t really get into details of how the piece rate is arrived at. Assumptions taken for piece rate calculation such as number of people planned to be deployed, skill levels of people considered, and wage rate assumed for each level leave a lot of room for optimisation. Once the value is unearthed, companies rationalise the number of contractors and increase share of business with a few contractors to realise the value unearthed.
Another innovative lever in white collar manpower is evaluating the people deployment/ cost incurred by core and non-core functions and exploring possibilities of managed services for non-core functions. Payroll/ IT service functions are mostly outsourced by many companies but companies today have started looking at other subfunctions/functions such as recruitment / tax / accounting where service providers are asked to reduce cost of service year on year through automation and digital interventions and. Another trend we see is even the non-core activities of core functions like procurement are being actively outsourced. The strategy here is to make variable the fixed costs, which helps companies in downturn to still stay profitable.
While we have deliberated on strategies for three top cost heads with a few levers, there are other cost heads such as indirect spend and packaging costs, which also provide more optimisation potential. The need of the hour for cement players is to think of an innovative approach to cost optimisation with new levers, to achieve higher order bottomline benefits.
About the author:
S Sathish, Partner and National Sector Leader- Industrial Manufacturing, KPMG, is responsible for increasing revenues for the industrial manufacturing sector, and increasing penetration in sector key accounts/corridors. He has rich experience in auto, industrial manufacturing and consumer market sectors. He has delivered more than 100+ engagements in India and abroad in his 27 years of experience.
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