Concrete

Role of Gasification

Published

2 years ago

January 19, 2024

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Dr Prateek Sharma, KPK Reddy, Moon Chourasia and Dr DK Panda, National Council for Cement and Building Materials (NCCBM), Ballabgarh, India, present their ideas on the integration of high ash refuse derived fuel and the role of gasification in the cement manufacturing process.

Refuse derived fuel (RDF) has been identified as one of the major fuels for the Indian cement industry to achieve TSR of around 30 per cent by 2030. However, challenges persist in maximising RDF utilisation in cement production like incomplete combustion, increased specific heat consumption, and inconsistent RDF quality due to varying sources and moisture content which can be overcome by RDF gasification. Gasification of RDF produces syngas that can be used as fuel, offering advantages in terms of combustion efficiency and clinker quality, particularly valuable for white cement manufacturing. Moreover, the ash produced in the gasification process can be repurposed as an alternative raw material. Experimental runs in a downward draft gasifier demonstrated the feasibility of RDF gasification and RDF-biomass co-gasification. A multi-zone gasifier model was also developed to simulate RDF gasification, taking into account the heterogeneous nature of RDF. The model successfully predicted the properties of the producer gas in each zone, providing a valuable tool for optimising gasification processes.
Nature of solid waste changes as societies get richer and more urbanised. Instead of biodegradable waste (wet), households generate more and more quantities of plastics, metals, and other non-biodegradable (dry) waste. 65 million tonnes of waste are generated annually in India of which over 62 million tonne is the share of Municipal Solid Waste (MSW). Only about 75-80 per cent of the municipal waste gets collected and out of this only 22- 28 per cent is processed and treated. The remaining MSW is deposited at dump yards. With population explosion and urbanisation, this trajectory is expected to reach 165 million tonnes by 2031, and up to 436 million tonnes by 2045. With this precipitous rise in the quantity of waste generated, the waste collection efficiency in India still has a lot to catch up.
RDF is a form of MSW that has been sorted and subject to basic processing treatment. MSW is treated by shredding and dehydrating to produce Refuse Derived fuel (RDF). It largely comprises combustible components of municipal waste which has more consistent combustion characteristics than unsorted MSW. RDF roughly comprises 15-20 per cent of MSW. As per the current scenario, the availability of RDF, considering the proximity of cement plants in India, is estimated to be around 13600 tonnes of RDF per day, equivalent to 4.96 million tonnes per annum. The Indian cement industry has improved to around 7 per cent thermal substitution rate (TSR) and is targeting to achieve 30 per cent TSR by 2030. Currently, all high TSR plants (14-30 per cent) are using RDF and plastics as major fuel with 69 per cent share in quantity. Currently, biomining is also being practised all over the country’s landfills to produce fractions comprising RDF, biodegradable matter, compost, and inert component. RDF produced is being sent to cement plants. However, there are operational challenges.

CHALLENGES WITH RDF USAGE
The maximum thermal substitution rate (TSR) achieved through RDF is 80-100 per cent in the calciner, while it is limited to 50-60 per cent in the kiln burner. Different AF pre-combustion technologies, advancements in multi-channel burners, and new satellite burners have supported high TSR worldwide. Extensive efforts in modelling kiln burners and calciners lead to enhanced TSR. However, the cement industry still faces fundamental operational issues such as high CO and incomplete combustion, increased specific heat consumption, reduced flame temperature, jamming and buildups. The nature of RDF including moisture content varies enormously with changes in sources. Improper segregation, low calorific value, high chloride content, cost fluctuations and poor characterisation facilities leads to an inconsistent quality altogether affecting the production and quality. Higher RDF utilisation sometimes requires a kiln bypass system which along with pre-processing also adds up as an additional cost.

RDF GASIFICATION AS A GAME CHANGER
RDF gasification can pose a promising solution to eliminate operational issues. Gasification is the thermal conversion of carbonaceous matter into a syngas by partial oxidation. Here the trash is heated in a low-oxygen environment to the point that it breaks down into its constituent molecules. This reaction has two products: a combustible gas called syngas and inert ash or char. Syngas can be directly burned in the calciner/kiln with minimal prior cleaning. Syngas has better combustion properties in the calciner than even small size solid waste directly fed to the calciner. Moisture will participate in gasification reactions to a certain extent and increase the NCV of syngas by contributing to H2 production through water gas shift reaction. NCV variations of the input fuel mix (coal and syngas) are reduced substantially due to consistent syngas composition. Moreover, it offers better clinker quality due to no additional ash in the clinker. No ash absorption by clinker can also facilitate the usage of marginal and low-grade limestone. Thus, a hard-to-burn fuel can be made easily combustible. Gasification integration with the cement industry will help achieve the target of 25 per cent TSR within the timeframe. The GOI has set a target of 100 million tonnes of coal gasification by the year 2030. This will also facilitate co-gasification of coal and waste, having the advantage of improved syngas quality.

GASIFIER INTEGRATION CONFIGURATIONS
There can be different configurations for integrating the gasifier with the pyroprocessing system reported in literature. Fuel gasification taking place in a gasifier in the presence of kiln exhaust gas at high temperature along with a portion of tertiary air from the cooler can be one option. Syngas gets burnt in the calciner in the presence of balanced tertiary air to provide heat for raw meal calcination. Tertiary air is split between calciner and gasifier. Another configuration involves a unique concept of separate hydrogen production taking advantage of the cement manufacturing process. Ash from the gasifier can be sent to the smoke chamber where some unburnt carbon present in ash will get burnt, and the heating value can be utilised for combustion purpose. Another way of ash utilisation is an alternative raw material. The syngas can also prove to be very helpful in white cement manufacturing. As per IS 8042, the iron content in white cement should be less than 1 per cent and the degree of whiteness should be greater than 70 per cent. As syngas has no residual ash, the whiteness index and iron content can be easily maintained. One configuration involves a separate gasifier set up and syngas produced being sent to the calciner replacing conventional fuel.

MODELLING and EXPERIMENTAL RUNS
National Council for Cement and Building Materials (NCCBM) in collaboration with the Birla Institute of Technology (BITS) Pilani-Pilani campus carried out experimental runs in a downward draft gasifier for RDF gasification and RDF-biomass mix co-gasification. RDF contains ash in the range of 30-50 per cent. A multizone gasifier model was developed for RDF gasification having four zones, i.e., drying, pyrolysis, oxidation/combustion and reduction/gasification. In each zone, different thermochemical phenomena occur. A stoichiometric approach is followed for modelling the drying, pyrolysis and combustion zone. The reduction zone is modelled as a cylindrical fixed bed reactor with a uniform cross-sectional area. The developed differential equations are solved using simulation software to predict the producer gas properties. Further, to study the integration of gasifier with calciner, a stoichiometric based model has been developed for calciner along with material and energy balance which predicted calciner outlet temperatures, gas composition, SO2 and CO2 for co-processing of producer gas as an alternative fuel in white cement plant replacing petcoke at 15 per cent TSR.

RESULTS
Gasification experiments were performed with RDF fluff and RDF pelléts as feedstock and air as gasifying agents. The gas yield ranges from 2.43-3.65 Nm/kg RDF with LHV of 1.87-2.24 MJ/Nm3 RDF and cold gas efficiency of 44-60 per cent. It is observed that RDF containing high ash content in the range of ~31-51 per cent is quite challenging to gasify in a downdraft-type gasifier with operational bridging and clinker formation issues. Upon adding O2 to air as a gasifying agent, LHV and CGE increased by 78 per cent and 30 per cent, respectively further, more experimental runs were carried out using RDF and biomass mix in different ratios using air as a gasifying agent. RDF-biomass mix co-gasification results are better than RDF gasification in terms of LHV and CGE. Upon adding O2 to air as a gasifying agent for a 50:50 RDF-biomass mix, LHV and CGE uncreased by 35.5 per cent and 8.35 per cent, respectively.
The proposed multizone gasifier model can predict the output of each zone satisfactorily since the model assumptions are more realistic and cater to the heterogeneous nature of RDF. The impact of equivalence ratio (ER), moisture content and reduction zone length on the performance of the gasifier are evaluated. For calciner modelling at 15 per cent
TSR, the model predicted the calciner outlet temperature accurately compared to the baseline scenario (100 per cent petcoke firing). Considering the biogenic content in RDF, CO2 mitigation potential due to RDF utilisation as producer gas is estimated to be 10.5 per cent of the baseline scenario at 15 per cent TSR.

CONCLUSION
RDF gasification stands out as a transformative approach to address operational challenges encountered in maximising RDF utilisation. By converting RDF into a syngas, this method provides several advantages apart from overcoming the current operational challenges during co-processing of RDF in cement production. The experimental runs and modelling efforts conducted in this research explore the viability of RDF gasification as a game-changing solution. This aligns well with India’s broader environmental, energy and waste utilisation objectives, positioning RDF gasification as a sustainable and efficient means of addressing the growing issue of solid waste while contributing to the country’s sustainability goals.

ABOUT THE AUTHORS

Dr Prateek Sharma is an energy auditor, manager at Centre for Mining, Environment, Plant Engineering, and Operations. He is also a Programme Leader of Advanced Fuel Technology programme at NCCBM.

KPK Reddy is an energy auditor, Manager at Centre for Mining, Environment, Plant Engineering and Operations. He is also a member of Project Engineering and System Design at NCCBM.

Moon Chourasia is a Project Scientist at the Centre for Mining, Environment, Plant Engineering and Operations at NCCBM.

Joint Director, NCB has over 36 years of experience in the areas of Geology, Raw Materials and Mining and administrative experience as a Team Leader, Programme Leader and Head of the Centre. He has executed more than 50 major industrial R&D projects.

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JSW Cement Begins Production At Nagaur Rajasthan Plant

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13 hours ago

March 23, 2026

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JSW Cement has started production at a new greenfield integrated cement plant in Nagaur, Rajasthan, marking its first integrated facility in north India. The commissioning advances its national expansion and raises cement grinding capacity to 24.1 million tonnes per annum (MTPA) and clinker manufacturing capacity to nine point seven four MTPA including joint venture capacity. The plant is strategically located to serve high growth markets in Rajasthan, Haryana, Punjab and the National Capital Region.

The Nagaur plant comprises a three point three MTPA clinkerisation unit and a two point five MTPA cement grinding unit, with an additional one MTPA grinding unit under construction. The facility’s capacity additions enable it to meet regional demand and support infrastructure development. The project was funded by equity and long term debt and the company allocated Rs 8 bn from IPO proceeds to part finance the unit.

Company leadership said commissioning was completed within 21 months and that the expansion advances its aim to become a pan India player, with a mid term target of 41.85 MTPA and a long term vision of 60 MTPA. The plant includes sustainability features such as co processing of alternative fuels and a seven kilometre overland belt conveyor to transport limestone from the mines, reducing road transport impacts. The operation is expected to support economic growth and provide supplies for construction projects across the north.

The site will incorporate a 16 megawatt (MW) Waste Heat Recovery System to capture and reuse process heat, reducing the carbon footprint. JSW Cement’s operations include eight plants in India and a clinker unit in the UAE through a joint venture, providing a presence across the building materials value chain. The company emphasised use of industrial by products in manufacture and focus on producing eco friendly building materials.

Concrete

MAPEI India Celebrates 15 Years of Building Excellence

MAPEI India celebrates 15 years with growth, expansion and CSR impact

Published

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Concrete

Material Flow Efficiency

Published

6 days ago

March 18, 2026

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We explore how material handling systems are becoming strategic assets in cement plants, enabling efficient movement of raw materials, clinker and finished cement. Advanced conveying, automation and digital technologies are improving plant productivity while supporting energy efficiency and sustainability goals.

Material handling systems form the operational backbone of cement plants, enabling the efficient movement of raw materials, clinker and finished cement across complex production networks. With India’s cement industry producing over 391 million tonnes of cement in FY2024 and possessing an installed capacity of around 668 mtpa, according to the CRISIL Research Industry Report, 2025, efficient material logistics have become critical to maintaining plant productivity and cost competitiveness. At the same time, cement production is highly energy intensive and contributes around 7 per cent to
8 per cent of global CO2 emissions, making efficient material flow and logistics optimisation essential for reducing operational inefficiencies and emissions states the International Energy Agency Cement Technology Roadmap, 2023. As plants scale capacity and integrate digital technologies, modern material handling systems, ranging from automated conveyors to intelligent stockyards, are increasingly recognised as strategic assets that influence plant stability, energy efficiency and environmental performance.

Strategic role of material handling
Material handling is no longer viewed as a secondary utility within cement plants; it is now recognised as a strategic system that directly influences production efficiency and process stability.
Cement manufacturing involves the continuous movement of large volumes of limestone, clay, additives, clinker and finished cement across multiple production stages. Even minor disruptions in conveying systems or storage infrastructure can lead to kiln feed fluctuations, production delays and significant financial losses. According to Indian Cement Industry Operational Benchmarking Study, 2024, unplanned downtime in large integrated cement plants can cost between Rs.15–20 lakh per hour, highlighting the economic importance of reliable material handling systems.
Modern cement plants are therefore investing in advanced mechanical handling systems designed for high throughput and operational reliability. Large integrated plants can process over 10,000 tonnes per day of clinker, requiring highly efficient conveying systems and automated stockyards to maintain continuous material flow, suggests the International Cement Review Industry Analysis, 2024. Efficient material handling also reduces spillage, minimises dust emissions and improves workplace safety. As cement plants become larger and more technologically advanced, the role of material handling is evolving from simple transport infrastructure to a critical operational system that supports both productivity and sustainability.

From quarry to plant
The transport of raw materials from quarry to processing plant represents one of the most energy-intensive stages of cement production. Traditionally, limestone and other raw materials were transported using diesel-powered trucks, which resulted in high fuel consumption, dust generation and increased operational costs. However, modern plants are increasingly adopting long-distance belt conveyors and pipe conveyors as a more efficient alternative. These systems allow continuous material transport over distances of 10–15 kilometres, significantly reducing fuel consumption and operating costs while improving environmental performance, states the FLSmidth Cement Industry Technology Report, 2024.
Milind Khangan, Marketing Manager, Vertex Market Research & Consulting, says, “Efficient and enclosed handling of fine materials such as cement, fly ash and slag requires modern pneumatic conveying systems. By optimising the air-to-material ratio, these systems can reduce energy consumption by 10 per cent to 15 per cent while ensuring smooth material flow. Closed-loop conveying further minimises dust loading and improves the performance of bag filters, supporting cleaner plant operations. In addition, flow-regulated conveying lines help prevent clogging and maintain reliable dispatch performance. Overall, automation in pneumatic conveying delivers immediate operational benefits, including improved equipment uptime, lower energy use, reduced material spillage and more stable kiln and mill performance.”
Pipe conveyor systems are particularly gaining traction because they provide a completely enclosed transport system that prevents material spillage and dust emissions. According to global cement engineering studies, conveyor-based transport can reduce energy consumption by up to 30 per cent compared to truck haulage, while also improving operational reliability. Several cement plants in India have already implemented such systems to stabilise quarry-to-plant logistics while reducing carbon emissions associated with diesel transport.

Stockyard management and homogenisation
Stockyards play a critical role in maintaining raw material consistency and stabilising kiln feed quality. Modern cement plants use advanced stacker and reclaimer systems to ensure efficient storage and blending of raw materials before they enter the grinding and pyroprocessing stages. Automated stacking methods such as chevron or windrow stacking enable uniform distribution of materials, while bridge-type or portal reclaimers ensure consistent extraction during kiln feed preparation. These systems are essential for maintaining stable chemical composition of raw meal, which directly influences kiln efficiency and clinker quality. The Cement Plant Operations Handbook, 2024 indicates that advanced homogenisation systems can reduce raw mix variability by up to 50 per cent, significantly improving kiln stability and energy efficiency. Integrated stockyard management systems also incorporate sensors for monitoring bulk density, moisture levels and stockpile volumes, enabling real-time control over material blending processes.

Clinker and cement conveying technologies
Once clinker is produced in the kiln, it must be efficiently transported to storage silos and subsequently to grinding and packing units. Modern cement plants rely on high-capacity belt conveyors, bucket elevators and pneumatic conveying systems to manage this stage of material flow. Steel-cord belt bucket elevators are now capable of lifting materials to heights exceeding 120 metres with capacities reaching 1,500 tonnes per hour, making them suitable for large-scale clinker production lines, states the European Cement Engineering Association Technical Paper, 2023.
For fine materials such as cement, fly ash and slag, pneumatic conveying systems provide a reliable and dust-free solution. These systems transport powdered materials using controlled airflow, ensuring enclosed and contamination-free movement between grinding units, silos and packing stations. Optimised pneumatic systems can reduce energy consumption by 10 per cent to 15 per cent compared to older conveying technologies, while also improving plant cleanliness and environmental compliance, according to the Global Cement Technology Review, 2024.

Automation and digitalisation
Digitalisation is transforming material handling systems by introducing real-time monitoring, predictive maintenance and automated control. Advanced sensors and Industrial Internet of Things (IIoT) platforms enable plant operators to track conveyor health, stockpile levels and equipment performance in real time. Predictive maintenance systems analyse vibration patterns, temperature fluctuations and equipment load data to detect potential failures before they occur. According to McKinsey’s Industry 4.0 Manufacturing Report, 2023, for heavy industries, digital monitoring and predictive maintenance technologies can reduce equipment downtime by up to 30 per cent and increase productivity by 10 per cent to 15 per cent. Digital control centres also integrate data from conveyors, stacker reclaimers and dispatch systems, enabling centralised management of material flows from quarry to dispatch.

Handling of AFR
The growing adoption of Alternative Fuels and Raw Materials (AFR) has introduced new challenges and opportunities for material handling systems in cement plants. AFR materials such as refuse-derived fuel (RDF), biomass and industrial waste often have irregular particle sizes, variable moisture content and lower bulk density compared to conventional fuels. As a result, specialised storage, dosing and feeding systems are required to ensure consistent kiln combustion. According to the Cement Sector Decarbonisation Roadmap published by NITI Aayog in 2026, increasing the use of AFR could enable India’s cement sector to achieve thermal substitution rates of around 20 per cent in the coming decades. To support this transition, plants are investing in automated receiving stations, shredding units, drying systems and precision dosing equipment to stabilise AFR supply and combustion performance.

Energy efficiency and dust control
Material handling systems also play a crucial role in improving plant energy efficiency and environmental performance. Modern conveyor systems equipped with variable speed drives and energy-efficient motors can significantly reduce electricity consumption. Permanent magnet motors used in conveyor drives can deliver 8 per cent to 12 per cent energy savings compared to conventional induction motors, improving overall plant energy efficiency according to the IEA Industrial Energy Efficiency Study, 2023. Dust control is another major concern in cement plants, particularly during material transfer and storage operations. Enclosed conveyors, dust extraction systems and advanced bag filters are widely used to minimise particulate emissions and improve workplace safety.

Future trends in material handling
The future of material handling in cement plants will be shaped by automation, digitalisation and sustainability considerations. Emerging technologies such as AI-driven logistics optimisation, autonomous mobile equipment and digital twins are expected to further improve plant efficiency and operational visibility. Digital twin models allow engineers to simulate material flow patterns, optimise stockyard operations and predict equipment performance under different operating conditions. According to the International Energy Agency Digitalisation and Energy Report, 2024, the adoption of advanced digital technologies could improve industrial energy efficiency by up to 20 per cent in heavy industries such as cement manufacturing. As cement plants expand capacity and adopt low-carbon technologies, intelligent material handling systems will play a critical role in maintaining productivity and reducing environmental impact.

Conclusion
Material handling systems have evolved from basic transport infrastructure into strategic operational systems that directly influence plant efficiency, reliability and sustainability. From quarry transport and automated stockyards to digital dispatch platforms and advanced conveying technologies, modern material handling solutions enable cement plants to manage large production volumes while maintaining process stability.
As India’s cement industry continues to expand to meet infrastructure and urban development demands, investments in advanced material handling technologies will become increasingly important. By integrating automation, digital monitoring and energy-efficient systems, cement manufacturers can improve operational performance while supporting the industry’s long-term sustainability and decarbonisation goals.