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Maximising AFR in Cement Manufacturing

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9 months ago

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Shreesh A Khadilkar, Consultant and Advisor, and Former Director Quality and Product Development, ACC Ltd Thane, discusses the importance of optimising the use of alternative fuel and raw materials (TSR percentage) in cement production without affecting clinker quality.

We all know that in the calciner the CaCO3 undergoes calcination producing CaO, part of this CaO reacts with Al2O3, Fe2O3 SiO2 to form aluminates, ferrites, Belite and some CaO remain as uncombined CaO in the material that enters the kiln, this uncombined CaO further reacts, as the material passes through the kiln to form clinker of desired phase composition with at desired levels of free lime. If this uncombined CaO is less, the resultant clinker would have lower free CaO.
Due to fluctuations of moisture in the SAFR feed, the calciner outlet temperature tends to decrease/fluctuate although the calcination is complete, some of the above post calcination reactions of the CaO are decreased, as a result the uncombined CaO is higher, in the material entering the kiln. The reactions in the kiln are affected for the same throughput and either the clinker free lime is high or the clinker shows lesser C3S percentage (depending on the burnability of the kiln feed).
In plants equipped with XRD it would be possible to monitor the uncombined CaO in Hot meal and optimise the Calciner outlet temperatures so as to achieve the desired uncombined percentage of lime as explained above. If the value is much lower than the desired level it would indicate subsequent lower LSF in the clinker, so addition of lime sludge or limestone powder as explained above would maintain the desired clinker specs. These actions, if affected during the day, would help maintain the day’s average clinker quality.
Besides the variability of the moisture percentage, the ash percentage and its composition in SAFR could change the composition of calcining material and finally depending on these changes, the post calcination reactions would be affected, depending on the uncombined percentage of lime value (monitored by XRD of hot meal), the corrections as explained above would help correct the composition and maintain the burning zone performance and the resultant clinker quality. Thus, if the calciner outlet temperature / kiln inlet material / C6 material temp. (as the case may be) is maintained higher and necessary corrections are made through SAFR or through the kiln feed. We can maintain the uncombined CaO at desired level where we could get good kiln performance as well as a good/improved clinker quality even at a higher percentage of AFR/TSR.
In many plants there is a tendency to increase the clinker Fe2O3 as and when there is an excessive dust generation and dusty kiln performance, this attempt to increase Clinker Fe2O3 would not actually help in improving the kiln conditions and maintaining clinker quality. In another plant equipped with XRD, the limestone had higher Fe2O3 content and to compensate for the effect of the varying moisture of SAFR the Calciner outlet temperature was maintained at around 920oC so that the desired post calcination reactions could be achieved and the uncombined CaO (monitored by XRD of hot meal) was maintained at desired levels.
The clinker LSF also could be maintained but the Free CaO tended to be high. The hot meal XRD indicated that the belite formations were lower in hot meal as and when the clinker free lime was high. Although the Silica was contributed from the Solid AFR as this silica was sand/silt, which did not react, the clinker IR also was observed to increase by around 0.4 per cent use of pondash (having reactive silica) along with the solid AFR up to 1 per cent was observed to increase the Belite content of hot meal and the resultant clinker had desired phase formations with lower free lime. For calculation of PSF/Potential phase composition a correction was given to the clinker silica contents (by subtracting the change in IR of clinker).
Thus, it needs to be noted here that in RDF/MSW, SAFR the ash content may have coarse sand grains, which cannot at the calcination stage and it the burnability is sensitive to silica contents, such corrections of use of wet fly ash with the SAFR could be advantageous to maintain clinker quality. However, these corrections have to be affected during the day through XRD monitoring of Hot meal and subsequent Clinker (say after 40 minutes) so that at the end of the day the clinker is of desired quality specs.
Thus, in plants coprocessing higher levels of AFR it is recommended to have a ‘bi-hourly dashboard’ and the day average clinker consistency in Quality Monitored by ‘compliance percentage to clinker specs’ as shown in Tables 1 and 2.
Such a dashboard helps having the entire plant operations involved in taking bi hourly actions so as to maintain the quality and process targets with increase in SAFR/LQAFR thus, achieving a higher compliance percentage to clinker quality specs. This has enabled not only to maintain clinker quality but it also showed improvements in clinker quality.

Actions: In plant with high TSR percentage without XRD
The hot meal samples at different kiln inlet material temperatures were collected at 870,900n and 930oC along with corresponding clinker samples (after say 40 minutes) and the XRD analysis was carried out at external labs. Through the bi-hourly dashboard actions the clinker compositions were maintained as per desired target. The XRD Mineralogy of Hot Meal and clinker XRD are tabulated in Table 3.
Although the plant maintains 95 per cent DOC, the XRD however indicates >99.5 per cent calcination. Thus, even in the absence of XRD using the bi-hourly dashboard optimisation of clinker quality can be made possible, however having an XRD (even a low watts XRD) would always be advantageous, especially if the kiln feed shows moderate burnability.

Other important considerations

  • As discussed above bi-hourly corrections made to clinker composition could be through the SAFR/RDF mix, in one plant it could be use of waste lime sludge/ in another plant use of wet pond ash/ in another use of limestone crusher dust/ high grade limestone powder depending on the corrections desired.
  • In case such materials are not available in the plant for corrections, the necessary actions bi-hourly, to adjust the clinker LSF, could be by changes in proportion of high ash coal + coal Petcoke mix in calciner or it could be even be targeting an appropriate kiln deed composition to accommodate the ash percentage of SAFR/RDF or bihourly changing the feed rate (TPH) of SAFR, as per the bi-hourly clinker composition requirements.
  • Reducing conditions can have substantial effects on clinker quality like problems with sulfur integration, Alite decomposition (strength reduction), conversion from C4AF to C3A (acceleration of setting), change in color of cement (from greenish grey to brownish), the detection of reducing conditions could be done using ‘Magotteaux Test’, it is important to assess the reducing conditions whether internal or peripheral, would indicate possible reasons.
  • Internal reducing conditions indicate that due to changes in liquid viscosity the larger clinker nodules are black from outside but yellow to brownish in the internal core. Such clinker nodules roll down from the transition zone with an unburnt core which disintegrates on cooling due to gamma C2S. Such nodules have high free lime, delocalised or peripheral reducing conditions due to larger size of solid AFR component (shredded size) showing CO peaks.
  • The Hot meal (2Cl+SO3) needs to be reliably monitored using XRF standards of Hot Meal. Every plant would have a threshold value of (2Cl+SO3), value >3.5 is reported to cause severe depositions at kiln inlet/riser duct/cyclones.
  • The kiln system should be able to handle the higher gas volumes (calciner , inlet and preheater).
    Increased percentage of AFR /TSR is associated with increase in limestone pile LSF which is linked to life of mines (Fig:2). This increase in limestone pile LSF would be more plant specific.
  • To lessen the impact on limestone Pile LSF/Mines life the plant would have to use, sweetener limestone (availability/cost), reduce the percentage use of high silica correctives with purer correctives, use petcoke or low ash coal (imported), use of waste lime sludges available from chemical industries.
  • As discussed earlier the plant could use a mix fuel (petcoke + high ash coal), or (mix of petcoke + high ash wastes like Dolochar/spent carbon etc.) in the calciner, the mix ratio could be changed so as to improve clinker LSF during the day (as a bi-hourly actions).
    High ash (high iron/high silica) wastes should not be fired through the kiln fuel; these wastes should be put through calciner fuel if feasible or along with solid wastes. It is always beneficial to have low ash coal (fuel) / petcoke in kilns.
  • It is recommended to use 4 per cent to 5 per cent high LSF Limestone in petcoke grinding (especially for kiln fuel). It improves the efficiency of petcoke grinding and would help to bind the sulphur during combustion in kiln, thus decreasing the SO3 of the hot meal. Using limestone decreases the SO3 fluctuations in the clinker and the excess of CaCO3 forms C3S clusters in the clinker, thus, improving clinker grindability.
  • Petcoke grinding is usually controlled at 1 per cent to 2 per cent on 90 microns. However in certain grinding systems, the 45 microns residue is observed to be as high as 26 per cent to 28 per cent which could create reducing conditions and initiate some coating formation in pre pre-transition zone in kilns.
  • Large storage yards to stock different types of solid AFR would help to mix the waste in certain proportions so as to achieve relative consistency in ash percentage or even chloride contents.
  • An auto-sampler with shredder on the solid AFR conveyor would be useful. However, the analysis time would be around 4 to 5 hours which is too high.
  • If the plant is reaching >25 per cent TSR, from a futuristics angle, having an online Cross Belt analyser like ‘Spectra Flow’ could help analyse moisture percentage, ash percentage and its constituents in real time, enabling rapid corrections to clinker compositions with necessary modifications to the kiln system even much higher TSR levels could be achievable.
  • Higher TSR levels invariably are associated with increase in Hot meal alkalis, chlorides and sulphates and would necessitate chloride bypass.
  • The procurement has a high responsibility of providing appropriate SAFR/RDF fuel of different ash percentage and of different chloride percentage (screened to remove sand/mud/stones).
  • Wastes having CaO rich ash would always be advantageous for the same TPH of solid AFR, the TSR percentage would be higher if the NCY of the sold AFR is higher.

Conclusion
The paper indicates and discusses in some details the avenues for increased TSR percentage without affecting clinker quality. However, depending on calciner retention time and air volume availability there would be a certain maximum TSR percentage that can be achieved. It may be noted here that the kiln system would necessitate suitable upgradation for achieving a much higher TSR percentage. It is needless to mention that XRF Models with standardless software for elemental analysis of solid/liquid AFR would be advantageous and as discussed having an XRD would be a necessity to maintain clinker quality at higher TSR percentage.
Clinkers with High MgO (>4.5 per cent) would be a challenge and optimising the CaO/SiO2 ratio would be a key to improve clinker quality use of XRD in such clinkers would be an asset.
Futuristically, ‘Torrefaction Process’ (the process of degrading organic materials in a nitrogen or inert environment within a temperature range of 200oC to 300oC) of bio wastes if extended suitably to MSW wastes and other solid AFR to produce a bio coal, could become an excellent opportunity for increased TSR for cement plants.
In this paper I have tried to share some observations in a generalised manner made at different plants with different AFR/TSR percentage which could be useful for other plants for their future road map on maximising TSR percentage.

About the author:
Shreesh Khadilkar, Consultant and Advisor brings over 37 years of experience in cement manufacturing, having held leadership roles in R&D and product development at ACC Ltd. With deep expertise in innovative cement concepts, he is dedicated to sharing his knowledge and improving the performance of cement plants globally.

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Adani’s Strategic Emergence in India’s Cement Landscape

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5 days ago

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September 16, 2025

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Milind Khangan, Marketing Head, Vertex Market Research, sheds light on Adani’s rapid cement consolidation under its ‘One Business, One Company’ strategy while positioning it to rival UltraTech, and thus, shaping a potential duopoly in India’s booming cement market.

India is the second-largest cement-producing country in the world, following China. This expansion is being driven by tremendous public investment in the housing and infrastructure sectors. The industry is accelerating, with a boost from schemes such as PM Gati Shakti, Bharatmala, and the Vande Bharat corridors. An upsurge in affordable housing under the Pradhan Mantri Awas Yojana (PMAY) further supports this expansion. In May 2025, local cement production increased about 9 per cent from last year to about 40 million metric tonnes for the month. The combined cement capacity in India was recorded at 670 million metric tonnes in the 2025 fiscal year, according to the Cement Manufacturers’ Association (CMA). For the financial year 2026, this is set to grow by another 9 per cent.
In spite of the growing demand, the Indian cement industry is highly competitive. UltraTech Cement (Aditya Birla Group) is still the market leader with domestic installed capacity of more than 186 MTPA as on 2025. It is targeted to achieve 200 MTPA. Adani Cement recently became a major player and is now India’s second-largest cement company. It did this through aggressive consolidation, operational synergies, and scale efficiencies. Indian players in the cement industry are increasingly valuing operational efficiency and sustainability. Some of the strategies with high impact are alternative fuels and materials (AFR) adoption, green cement expansion, and digital technology investments to offset changing regulatory pressure and increasing energy prices.

Building Adani Cement brand
Vertex Market Research explains that the Adani Group is executing a comprehensive reorganisation and consolidation of its cement business under the ‘One Business, One Company’ strategy. The plan is to integrate its diversified holdings into one consolidated corporate entity named Adani Cement. The focus is on operating integration, governance streamlining, and cost reduction in its expanding cement business.
Integration roadmap and key milestones:

  • September 2022: The consolidation process started with the $6.4 billion buyout of Holcim’s majority stakes in Ambuja Cements and ACC, with Ambuja becoming the focal point of the consolidation.
  • December 2023: Bought Sanghi Industries to strengthen the firm’s presence in western India.
  • August 2024: Added Penna Cement to the portfolio, improving penetration of the southern market of India.
  • April 2025: Further holding addition in Orient Cement to 46.66 per cent by purchasing the same from CK Birla Group, becoming the promoter with control.
  • Ambuja Cements amalgamated with Adani Cement: This was sanctioned by the NCLT on 18th July 2025 with effect from April 1, 2024. This amalgamation brings in limestone reserves and fresh assets into Ambuja.
  • Subject to Sanghi and Penna merger with Ambuja: Board approvals in December 2024 with the aim to finish between September to December 2025.
  • Ambuja-ACC future integration: The latter is being contemplated as the final step towards consolidation.
  • Orient Cement: It would serve as a principal manufacturing facility following the merger.

Scale, capacity expansion and market position
In financial year-2025, Adani Cement, including Ambuja, surpassed 100 MTPA. This makes it one of the world’s top ten cement companies. Along with ACC’s operations, it is now firmly placed as India’s second-largest cement company. In FY25, the Adani group’s sales volume per annum clocked 65 million metric tonnes. Adani Group claims that it now supplies close to 30 per cent of the cement consumed in India’s homes and infrastructure as of June 2025.
The organisation is pursuing aggressive brownfield expansion:

  • By FY 2026: Reach 118 MTPA
  • By FY 2028: Target 140 MTPA

These goals will be driven by commissioning new clinker and grinding units at key sites, with civil and mechanical works underway.
As of 2024, Adani Cement had its market share pegged at around 14 to 15 per cent, with an ambition to scale this up to 20 per cent by FY?2028, emerging as a potent competitor to UltraTech’s 192?MTPA capacity (186 domestic and overseas).

Strategic advantages and competitive benefits
The consolidation simplifies decision-making by reducing legal entities, centralising oversight, and removing redundant functions. This drives compliance efficiency and transparent reporting. Using procurement power for raw materials and energy lowers costs per ton. Integrated logistics with Adani Ports and freight infrastructure has resulted in an estimated 6 per cent savings in logistics. The group aims for additional savings of INR 500 to 550 per tonne by FY 2028 by integrating green energy, using alternative fuel resources, and improving sourcing methods.

Market coverage and brand consistency
Brand integration under one strategy will provide uniform product quality and easier distribution networks. Integration with Orient Cement’s dealer base, 60 per cent of which already distributes Ambuja/ACC products, enhances outreach and responsiveness.
By having captive limestone reserves at Lakhpat (approximately 275 million tonnes) and proposed new manufacturing facilities in Raigad, Maharashtra, Adani Cement derives cost advantage, raw material security, and long-term operational robustness.

Strategic implications and risks
Consolidation at Adani Cement makes it not just a capacity leader but also an operationally agile competitor with the ability to reap digital and sustainability benefits. Its vertically integrated platform enables cost leadership, market responsiveness, and scalability.

Challenges potentially include:

  • Integration challenges across systems, corporate cultures, and plant operations
  • Regulatory sanctions for pending mergers and new capacity additions
  • Environmental clearances in environmentally sensitive areas and debt management with input price volatility

When materialised, this revolution would create a formidable Adani–UltraTech duopoly, redefining Indian cement on the basis of scale, innovation, and sustainability. India’s leading four cement players such as Adani (ACC and Ambuja), Dalmia Cement, Shree Cement, and UltraTech are expected to dominate the cement market.

Conclusion
Adani’s aggressive consolidation under the ‘One Business, One Company’ strategy signals a decisive shift in the Indian cement industry, positioning the group as a formidable challenger to UltraTech and setting the stage for a potential duopoly that could dominate the sector for years to come. By unifying operations, leveraging economies of scale, and securing vertical integration—from raw material reserves to distribution networks—Adani Cement is building both capacity and resilience, with clear advantages in cost efficiency, market reach, and sustainability. While integration complexities, regulatory hurdles, and environmental approvals remain key challenges, the scale and strategic alignment of this consolidation promise to redefine competition, pricing dynamics, and operational benchmarks in one of the world’s fastest-growing cement markets.

About the author:
Milind Khangan is the Marketing Head at Vertex Market Research and comes with over five years of experience in market research, lead generation and team management.

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Precision in Motion: A Deep Dive into PowerBuild’s Core Gear Series

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1 month ago

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August 16, 2025

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PowerBuild’s flagship Series M, C, F, and K geared motors deliver robust, efficient, and versatile power transmission solutions for industries worldwide.

Products – M, C, F, K: At the heart of every high-performance industrial system lies the need for robust, reliable, and efficient power transmission. PowerBuild answers this need with its flagship geared motor series: M, C, F, and K. Each series is meticulously engineered to serve specific operational demands while maintaining the universal promise of durability, efficiency, and performance.
Series M – Helical Inline Geared Motors: Compact and powerful, the Series M delivers exceptional drive solutions for a broad range of applications. With power handling up to 160kW and torque capacity reaching 20,000 Nm, it is the trusted solution for industries requiring quiet operation, high efficiency, and space-saving design. Series M is available with multiple mounting and motor options, making it a versatile choice for manufacturers and OEMs globally.
Series C – Right Angled Heli-Worm Geared Motors: Combining the benefits of helical and worm gearing, the Series C is designed for right-angled power transmission. With gear ratios of up to 16,000:1 and torque capacities of up to 10,000 Nm, this series is optimal for applications demanding precision in compact spaces. Industries looking for a smooth, low-noise operation with maximum torque efficiency rely on Series C for dependable performance.
Series F – Parallel Shaft Mounted Geared Motors: Built for endurance in the most demanding environments, Series F is widely adopted in steel plants, hoists, cranes, and heavy-duty conveyors. Offering torque up to 10,000 Nm and high gear ratios up to 20,000:1, this product features an integral torque arm and diverse output configurations to meet industry-specific challenges head-on.
Series K – Right Angle Helical Bevel Geared Motors: For industries seeking high efficiency and torque-heavy performance, Series K is the answer. This right-angled geared motor series delivers torque up to 50,000 Nm, making it a preferred choice in core infrastructure sectors such as cement, power, mining, and material handling. Its flexibility in mounting and broad motor options offer engineers’ freedom in design and reliability in execution.
Together, these four series reflect PowerBuild’s commitment to excellence in mechanical power transmission. From compact inline designs to robust right-angle drives, each geared motor is a result of decades of engineering innovation, customer-focused design, and field-tested reliability. Whether the requirement is speed control, torque multiplication, or space efficiency, Radicon’s Series M, C, F, and K stand as trusted powerhouses for global industries.

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Driving Measurable Gains

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1 month ago

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August 16, 2025

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Klüber Lubrication India’s Klübersynth GEM 4-320 N upgrades synthetic gear oil for energy efficiency.

Klüber Lubrication India has introduced a strategic upgrade for the tyre manufacturing industry by retrofitting its high-performance synthetic gear oil, Klübersynth GEM 4-320 N, into Barrel Cold Feed Extruder gearboxes. This smart substitution, requiring no hardware changes, delivered energy savings of 4-6 per cent, as validated by an internationally recognised energy audit firm under IPMVP – Option B protocols, aligned with
ISO 50015 standards.

Beyond energy efficiency, the retrofit significantly improved operational parameters:

  • Lower thermal stress on equipment
  • Extended lubricant drain intervals
  • Reduction in CO2 emissions and operational costs

These benefits position Klübersynth GEM 4-320 N as a powerful enabler of sustainability goals in line with India’s Business Responsibility and Sustainability Reporting (BRSR) guidelines and global Net Zero commitments.

Verified sustainability, zero compromise
This retrofit case illustrates that meaningful environmental impact doesn’t always require capital-intensive overhauls. Klübersynth GEM 4-320 N demonstrated high performance in demanding operating environments, offering:

  • Enhanced component protection
  • Extended oil life under high loads
  • Stable performance across fluctuating temperatures

By enabling quick wins in efficiency and sustainability without disrupting operations, Klüber reinforces its role as a trusted partner in India’s evolving industrial landscape.

Klüber wins EcoVadis Gold again
Further affirming its global leadership in responsible business practices, Klüber Lubrication has been awarded the EcoVadis Gold certification for the fourth consecutive year in 2025. This recognition places it in the top three per cent
of over 150,000 companies worldwide evaluated for environmental, ethical and sustainable procurement practices.
Klüber’s ongoing investments in R&D and product innovation reflect its commitment to providing data-backed, application-specific lubrication solutions that exceed industry expectations and support long-term sustainability goals.

A trusted industrial ally
Backed by 90+ years of tribology expertise and a global support network, Klüber Lubrication is helping customers transition toward a greener tomorrow. With Klübersynth GEM 4-320 N, tyre manufacturers can take measurable, low-risk steps to boost energy efficiency and regulatory alignment—proving that even the smallest change can spark a significant transformation.

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