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Achieving Sustainability with LD Steel Slag

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The utilisation of Linz-Donawitz (LD) steel slag is a firm step towards achieving sustainability and players of the Indian cement industry need to focus on this to make a positive impact on the environment. Dr Asok K Dikshit, Dr Sanjeev Chaturvedi and Kirti Chugh from National Council for Cement and Building Materials (NCCBM) present a detailed study.

Slag is a by-product generated during the manufacturing of pig iron and steel. This is a solid industrial by-product of the iron and steel industry and mainly these wastes include blast furnace and steel melting slag. It can be categorised as carbon steel slag and stainless steel slag according to the type of steel, and as pre-treatment slag, Linz-Donawitz (LD) converter slag, electrical arc furnace slag (EAFS), ladle refining slag, and casting residue according to the steelmaking process. LD slag is generated by the Linz- Donawitz process from steel making process or pig iron refining process in oxygen converters [1-2]. One of the important wastes in all integrated steel plants is LD converter steelmaking slag. Worldwide generation of LD slag waste is about 47 MT per annum [3] and in India, the total generation rate of LD slag waste is (150-180) kg/t of crude steel [4] whereas, in SAIL, the generation per annum is 1.28 MT [5]. Steel melting slag generation is about 4 to 4.5 MT per annum. The amount of LD slag produced in Indian integrated steel plants is about 200 kg/t of hot metal. Out of this 70-100 per cent is being reused in other countries whereas only 25 per cent is being reused in India [6]. It has been observed that for the road project, for sintering and iron-making recycling in steel making plants, 50 per cent of slag has been used.


The generation of LD slag increases due to the rapid growth of industrialisation, the land available for disposal of large quantities of LD slag at a landfill site is deteriorating and disposal cost is increasing. Nowadays, the vital environmental topics are the issues on both the global warming effect and natural resource-saving. The significant source of pollution of air, water, and soil are land filled with waste materials, and hence human health, the growth of plants and vegetation, etc are adversely affected. From the viewpoint of conservation and protection of the global environment, steel slag recycling has attracted the attention of many scientists in recent years. Therefore, improving the utilisation rate of steel LD slag is an imperative way for the steel enterprise to realise sustainable development.


This by-product LD slag generated by Tata Steel BSL at present generates about 1 million tonnes of slag per annum. Tata Steel exports 9,000 tonnes of LD slag to the Bangladesh market through Dhamra Port Company Odisha state in 2021. As part of the quest for a sustainable future in the Cement Industry, LD slag is facing innovations by creating value out of its by-products. In collaboration with its cement industry, for applications in slag cement PSC, clinker making, and GGBS (Ground Granulated Blast Furnace Slag), (0-6) mm size slag range has been developed by steel major. LD slag is being supplied by Tata Steel BSL (as part of its sustainable operations of by-products) to brick makers near the plant for hard surfacing national highway work, and low land area filling, besides to cement companies also.

Basics of steel production and types of steel slag
Electric arc furnaces (EAF) or in basic oxygen processes for steel production are being used in all steel integrated. Molten metal and dolomitic lime (CaO.MgO) or fluxes lime (CaO) is placed in the furnace in the basic oxygen and EAF processes. In the furnace, high-pressure oxygen is injected with a lance. Several oxidised compounds are formed when oxygen reacts with carbon and non-iron impurities. Slag is formed when these compounds react with the lime or dolomitic lime. The slag remains while liquid steel is poured from the furnace which is then poured into a separate vessel. In the steel-making process, different types of slag produced are furnace or tap slag, synthetic or ladle slags, raker slag. Fig. 1 shows the production of different slag in the general flow in a modern steel plant. The nonmetallic products from the furnace, raker and ladle slags are used for different applications including as construction aggregate, in agriculture, or reclamation of acidic lands following processing and metal recovery [7].
Fig 2 shows the flow process during steel production operation and generation of by-product slag. BOFS is produced in the steelmaking process by using the molten iron coming from the BF. The slag contains various heavy metal carriers such as chrome, lead, or zinc that produce various types of slag.

Fig.3: SEM image of steel slag

The macrograph about structural morphology is shown in Fig.3. Particles of various sizes are agglomerated.

Physical, chemical and mineralogical characteristics of LD steel slag
It was found that the LD slag density lies between 3.3-3.6g/cm.3 Due to high Fe content in slag, steel slag looks like a loose collection in appearance, and appears hard and wear resistant. The grindability index of steel slag is 0.7, in comparison with the value of 0.96 and 1.0 for blast furnace slag and standard sand respectively. SiO2, CaO, Fe2O3, FeO, Al2O3, MgO, MnO, P2O5 are major constituents of LD slag . The main mineral phases in steel slag are dicalcium silicate (C2S), tricalcium silicate (C3S), RO phase (CaO-FeO-MnO-MgO solid solution), tetra-calcium aluminoferrite (C4AF), olivine, merwinite and free-CaO [8]. The reuse and recycle of the steel slag is closely related to the slag’s chemical and physical characteristics. For chemical and mineralogical characteristics of LD slag, many studies were done. ICP-AES and C-H-N-S analyser were used for chemical characterisation of LD slags. CaO, Fe, SiO2 and Mn are the main desirable substances [9].

Fig.4: LD slag based clinker


Table 1 summarises the major phases and chemical composition of steel slag generated at integrated steel plant in India [10].

Application of LD slag in cement industry and brick production
(a) Cement clinker using LD lag
The transformation of pig iron into liquid steel generates a significant quantity of LD slag in the steel-making process. The possibility of adding LD slag in the raw meal for the production of Portland clinker replacing iron ore. 0.6 mass per cent iron ore and 1.0, 2.0, and 3 mass per cent of iron ore being replaced by LD slag. The various components of LD slag were prepared in the different raw mixes in the laboratory and fired in a high-temperature muffle furnace at 1400°C, all raw mix samples were sintered. The ethylene glycol method is used to determine free lime to assess the comparative burnability of the raw mix samples. X-ray and X-ray fluorescence were employed to determine the chemical and mineralogical composition of the clinkers which showed that the mineralogical composition of the clinker was not altered on the addition of LD slag in the raw mix. The fluxing agent was the iron present in the LD slag and it replaced the iron ore requirement. Improvement in burnability and development of clinker mineral phases was shown by reduction in free lime and increase in C3S phase value with LD slag as shown in Fig 4. Under the optical microscope, homogeneously distributed and well-developed alite and belite phases were observed. A plant trial with 2 mass per cent LD slag as a raw mix component replacing iron ore was conducted, but no adverse impact in the pyro-processing system was observed, and operation of the kiln was found to be smooth and stable during the trial [11].
(b) Cement replacement with LD slag

Fig.5 LD Slag based blended cement


A study on partial replacement of cement with LD slag was done and its impact on the mechanical, microstructural, and durability properties of concrete were studied. Grindability is of major importance in the manufacture of slag blended cement. In terms of grindability, the incorporation of LD slag with particle size below 5mm can benefit the grinding of OPC clinker. Other particle size materials should be used for other applications in road bases etc. The addition of LD slag, at content levels of up to 20 per cent of total solid material, is suggested as optimum for the stability, economy, and strength of the blended cements as shown in Fig 5. Steel slag contains a similar mineral composition to that of OPC clinker; the slag may become unstable due to excess free lime (f-CaO). GBFS possesses hydraulic properties that can only be activated in the presence of an existing basic or sulfate activator such as CaO or CaS. This excess CaO steel slag could constitute
this activator.
(c) LD slag in brick production

Fig.6: Brick prepared from LD slag


LD steel slag is used in commercial brick manufacturing as shown in Fig.6. The characterisation results of LD slag showed that the pH and electrical conductivity of the samples were very high indicating high percentage of lime presence and presence of ionic form of various salts, respectively. The specific gravity and bulk density of LD slag samples were found to be high in comparison to fly ash samples. The major elemental compositions of LD slag samples are shown by weight Ca and oxygen. The CaO, FeO and SiO2 are the major components in the LD slag. The compressive strength was found to be more than 100 kg/cm2 for brick samples type A as shown in Fig 6 (Fly ash – 35 per cent + LD slag – 30 per cent + Gypsum – 5 per cent + Quarry dust – 20 per cent + Lime – 9.75 per cent + CaCl2 – 0.25 per cent) after 14 days of curing which is greater than 50-70 kg/cm2, i.e., strength of normal red clay bricks and maybe it is a feasible replacement for commercial purposes in civil jobs.

Summary
The steel industry is nowadays focused to increase the way for recycling slags generated during steel production. The pressure for saving energy and natural resources has led the steel industry to improve and increase the recycling of steel slag since its use as landfill material has almost reached its limit. Steel slag in most cases, the valorisation, and use of these by-products prevent landfill, reduce energy consumption, reduce CO2 emissions and help preserve natural resources. To neutralise soil acidity in agricultural soils for many years, LD slag has been successfully used as a substitute for limestone, and slag use is comparable to or superior to limestone in some cases. In addition to its limiting benefits, slag contains Si which has been shown to increase yields of crops, like rice and sugarcane, and Si is also helpful in defending crops against crop diseases. Slag also contains plant nutrients that can enhance plant growth. Considerable cost advantages are offered by steel slag over commercial limestone. In recent years, significant volatility in the cost of agricultural limestone is attributable in part to energy costs of production. To cover the rising costs of fertiliser, limestone use has been deferred by Cultivators, even at the risk of lower yields. The application of LD slag as a cementitious component instead of aggregate in concrete would boost its reuse and will reduce the cost of construction and production of greenhouse gases significantly. The main constraint with the usability of LD slag is the high amount of free MgO and free CaO content, which leads to volumetric changes. At the same time, owing to calcined materials present in LD slag, its potential to be used as a partial substitution of OPC Granulated slag is used for the manufacture of hydraulic cement by mixing Portland cement clinker, gypsum, and granulated slag in suitable proportions and grinding the mixture to get a thorough and intimate mix between the constituents. There is IS code for GBFS, i.e., IS 12089:1987 but for LD slag utilisation in the construction industry for infrastructure development is in the interfacial stage, more research work is required for innovative solutions for its utilisation.

Acknowledgment
The authors are thankful to DPIIT, Ministry of Commerce and Industry (MoC&I), Government of India for supporting R&D funding to NCCBM in the favour of a circular economy.

References

  1. Alexandre, J., and Boudonnet, J.Y., Les laitiers d’aciérie LD et leurs utilisations routières. Laitier sidérurgiques., 75: 57–62 (1993).
  2. Shen, D. H., Wu, C. M., and Du, J. C., Laboratory investigation of basic oxygen furnace slag for substitution of aggregate in porous asphalt mixture. Constr Build Mater., 23: 453–61 (2009).
  3. Takano, Cyro et al., Recycling of Solid Waste From Integrated Steel Plant: A Sustainable Alternative. Materials Transactions., 42: 2560-2570 (2001).
  4. Yadav, U. S., Das, B. K., Kumar, A., and Sandhu, H. S., Solid waste recycling through sinter status at Tata Steel. In: Proceeding of Environment and Waste Management, NML, Jamshedpur, India, pp: 81-94 (2002).
  5. Basu, P., Alternative ironmaking technologies: an environmental impact analysis. In: Proceeding of Environment and Waste Management, NML, Jamshedpur, India, pp: 194-202 (2002).
  6. Umadevi, T., Rao, S. P., Roy, Pankaj., Mohapatra, P.C., Prabhu, M., and Ranjan, M., Influence of LD slag on iron ore sinter properties and productivity. In: 6th international seminar on mineral processing technology, NML, Jamshedpur, pp: 747-757 (2010).
  7. www.nationalslag.org
  8. Kourounis, S., Tsivilis, S., Tsakiridis, P.E. Papadimitriou, G. D., and Tsibouki, Z., Properties and hydration of blended cements with steelmaking slag. Cement Concrete Res., 37: 815-822 (2007).
  9. Waligora, J., Bulteel, D., Degrugilliers, P., Damidot, D., Potdevin, J. L., and Measson, M., Chemical and mineralogical characterisations of LD converter steel slag: A multi-analytical techniques approach. Mater Charact., 61: 39-48 (2010)
  10. Chand, S., Paul, B., & Kumar, M. (2015). An overview of use of Linz-Donawitz (LD) steel slag in agriculture. Current World Environment, 10(3), 975.
  11. Singh, A. K., Kukreti, N. C., Chandraker, V., Baury, M., Biswas, T., & Patil, K. D. (2015). Utilization of LD Slag for the production of Portland cement clinker. Cement International, 3, 70-76.

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Refractory demands in our kiln have changed

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Radha Singh, Senior Manager (P&Q), Shree Digvijay Cement, points out why performance, predictability and life-cycle value now matter more than routine replacement in cement kilns.

As Indian cement plants push for higher throughput, increased alternative fuel usage and tighter shutdown cycles, refractory performance in kilns and pyro-processing systems is under growing pressure. In this interview, Radha Singh, Senior Manager (P&Q), Shree Digvijay Cement, shares how refractory demands have evolved on the ground and how smarter digital monitoring is improving kiln stability, uptime and clinker quality.

How have refractory demands changed in your kiln and pyro-processing line over the last five years?
Over the last five years, refractory demands in our kiln and pyro line have changed. Earlier, the focus was mostly on standard grades and routine shutdown-based replacement. But now, because of higher production loads, more alternative fuels and raw materials (AFR) usage and greater temperature variation, the expectation from refractory has increased.
In our own case, the current kiln refractory has already completed around 1.5 years, which itself shows how much more we now rely on materials that can handle thermal shock, alkali attack and coating fluctuations. We have moved towards more stable, high-performance linings so that we don’t have to enter the kiln frequently for repairs.
Overall, the shift has been from just ‘installation and run’ to selecting refractories that give longer life, better coating behaviour and more predictable performance under tougher operating conditions.

What are the biggest refractory challenges in the preheater, calciner and cooler zones?
• Preheater: Coating instability, chloride/sulphur cycles and brick erosion.
• Calciner: AFR firing, thermal shock and alkali infiltration.
• Cooler: Severe abrasion, red-river formation and mechanical stress on linings.
Overall, the biggest challenge is maintaining lining stability under highly variable operating conditions.

How do you evaluate and select refractory partners for long-term performance?
In real plant conditions, we don’t select a refractory partner just by looking at price. First, we see their past performance in similar kilns and whether their material has actually survived our operating conditions. We also check how strong their technical support is during shutdowns, because installation quality matters as much as the material itself.
Another key point is how quickly they respond during breakdowns or hot spots. A good partner should be available on short notice. We also look at their failure analysis capability, whether they can explain why a lining failed and suggest improvements.
On top of this, we review the life they delivered in the last few campaigns, their supply reliability and their willingness to offer plant-specific custom solutions instead of generic grades. Only a partner who supports us throughout the life cycle, which includes selection, installation, monitoring and post-failure analysis, fits our long-term requirement.

Can you share a recent example where better refractory selection improved uptime or clinker quality?
Recently, we upgraded to a high-abrasion basic brick at the kiln outlet. Earlier we had frequent chipping and coating loss. With the new lining, thermal stability improved and the coating became much more stable. As a result, our shutdown interval increased and clinker quality remained more consistent. It had a direct impact on our uptime.

How is increased AFR use affecting refractory behaviour?
Increased AFR use is definitely putting more stress on the refractory. The biggest issue we see daily is the rise in chlorine, alkalis and volatiles, which directly attack the lining, especially in the calciner and kiln inlet. AFR firing is also not as stable as conventional fuel, so we face frequent temperature fluctuations, which cause more thermal shock and small cracks in the lining.
Another real problem is coating instability. Some days the coating builds too fast, other days it suddenly drops, and both conditions impact refractory life. We also notice more dust circulation and buildup inside the calciner whenever the AFR mix changes, which again increases erosion.
Because of these practical issues, we have started relying more on alkali-resistant, low-porosity and better thermal shock–resistant materials to handle the additional stress coming from AFR.

What role does digital monitoring or thermal profiling play in your refractory strategy?
Digital tools like kiln shell scanners, IR imaging and thermal profiling help us detect weakening areas much earlier. This reduces unplanned shutdowns, helps identify hotspots accurately and allows us to replace only the critical sections. Overall, our maintenance has shifted from reactive to predictive, improving lining life significantly.

How do you balance cost, durability and installation speed during refractory shutdowns?
We focus on three points:
• Material quality that suits our thermal profile and chemistry.
• Installation speed, in fast turnarounds, we prefer monolithic.
• Life-cycle cost—the cheapest material is not the most economical. We look at durability, future downtime and total cost of ownership.
This balance ensures reliable performance without unnecessary expenditure.

What refractory or pyro-processing innovations could transform Indian cement operations?
Some promising developments include:
• High-performance, low-porosity and nano-bonded refractories
• Precast modular linings to drastically reduce shutdown time
• AI-driven kiln thermal analytics
• Advanced coating management solutions
• More AFR-compatible refractory mixes

These innovations can significantly improve kiln stability, efficiency and maintenance planning across the industry.

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Digital supply chain visibility is critical

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MSR Kali Prasad, Chief Digital and Information Officer, Shree Cement, discusses how data, discipline and scale are turning Industry 4.0 into everyday business reality.

Over the past five years, digitalisation in Indian cement manufacturing has moved decisively beyond experimentation. Today, it is a strategic lever for cost control, operational resilience and sustainability. In this interview, MSR Kali Prasad, Chief Digital and Information Officer, Shree Cement, explains how integrated digital foundations, advanced analytics and real-time visibility are helping deliver measurable business outcomes.

How has digitalisation moved from pilot projects to core strategy in Indian cement manufacturing over the past five years?
Digitalisation in Indian cement has evolved from isolated pilot initiatives into a core business strategy because outcomes are now measurable, repeatable and scalable. The key shift has been the move away from standalone solutions toward an integrated digital foundation built on standardised processes, governed data and enterprise platforms that can be deployed consistently across plants and functions.
At Shree Cement, this transition has been very pragmatic. The early phase focused on visibility through dashboards, reporting, and digitisation of critical workflows. Over time, this has progressed into enterprise-level analytics and decision support across manufacturing and the supply chain,
with clear outcomes in cost optimisation, margin protection and revenue improvement through enhanced customer experience.
Equally important, digital is no longer the responsibility of a single function. It is embedded into day-to-day operations across planning, production, maintenance, despatch and customer servicing, supported by enterprise systems, Industrial Internet of Things (IIoT) data platforms, and a structured approach to change management.

Which digital interventions are delivering the highest ROI across mining, production and logistics today?
In a capital- and cost-intensive sector like cement, the highest returns come from digital interventions that directly reduce unit costs or unlock latent capacity without significant capex.
Supply chain and planning (advanced analytics): Tools for demand forecasting, S&OP, network optimisation and scheduling deliver strong returns by lowering logistics costs, improving service levels, and aligning production with demand in a fragmented and regionally diverse market.
Mining (fleet and productivity analytics): Data-led mine planning, fleet analytics, despatch discipline, and idle-time reduction improve fuel efficiency and equipment utilisation, generating meaningful savings in a cost-heavy operation.
Manufacturing (APC and process analytics): Advanced Process Control, mill optimisation, and variability reduction improve thermal and electrical efficiency, stabilise quality and reduce rework and unplanned stoppages.
Customer experience and revenue enablement (digital platforms): Dealer and retailer apps, order visibility and digitally enabled technical services improve ease of doing business and responsiveness. We are also empowering channel partners with transparent, real-time information on schemes, including eligibility, utilisation status and actionable recommendations, which improves channel satisfaction and market execution while supporting revenue growth.
Overall, while Artificial Intelligence (AI) and IIoT are powerful enablers, it is advanced analytics anchored in strong processes that typically delivers the fastest and most reliable ROI.

How is real-time data helping plants shift from reactive maintenance to predictive and prescriptive operations?
Real-time and near real-time data is driving a more proactive and disciplined maintenance culture, beginning with visibility and progressively moving toward prediction and prescription.
At Shree Cement, we have implemented a robust SAP Plant Maintenance framework to standardise maintenance workflows. This is complemented by IIoT-driven condition monitoring, ensuring consistent capture of equipment health indicators such as vibration, temperature, load, operating patterns and alarms.
Real-time visibility enables early detection of abnormal conditions, allowing teams to intervene before failures occur. As data quality improves and failure histories become structured, predictive models can anticipate likely failure modes and recommend timely interventions, improving MTBF and reducing downtime. Over time, these insights will evolve into prescriptive actions, including spares readiness, maintenance scheduling, and operating parameter adjustments, enabling reliability optimisation with minimal disruption.
A critical success factor is adoption. Predictive insights deliver value only when they are embedded into daily workflows, roles and accountability structures. Without this, they remain insights without action.

In a cost-sensitive market like India, how do cement companies balance digital investment with price competitiveness?
In India’s intensely competitive cement market, digital investments must be tightly linked to tangible business outcomes, particularly cost reduction, service improvement, and faster decision-making.
This balance is achieved by prioritising high-impact use cases such as planning efficiency, logistics optimisation, asset reliability, and process stability, all of which typically deliver quick payback. Equally important is building scalable and governed digital foundations that reduce the marginal cost of rolling out new use cases across plants.
Digitally enabled order management, live despatch visibility, and channel partner platforms also improve customer centricity while controlling cost-to-serve, allowing service levels to improve without proportionate increases in headcount or overheads.
In essence, the most effective digital investments do not add cost. They protect margins by reducing variability, improving planning accuracy, and strengthening execution discipline.

How is digitalisation enabling measurable reductions in energy consumption, emissions, and overall carbon footprint?
Digitalisation plays a pivotal role in improving energy efficiency, reducing emissions and lowering overall carbon intensity.
Real-time monitoring and analytics enable near real-time tracking of energy consumption and critical operating parameters, allowing inefficiencies to be identified quickly and corrective actions to be implemented. Centralised data consolidation across plants enables benchmarking, accelerates best-practice adoption, and drives consistent improvements in energy performance.
Improved asset reliability through predictive maintenance reduces unplanned downtime and process instability, directly lowering energy losses. Digital platforms also support more effective planning and control of renewable energy sources and waste heat recovery systems, reducing dependence on fossil fuels.
Most importantly, digitalisation enables sustainability progress to be tracked with greater accuracy and consistency, supporting long-term ESG commitments.

What role does digital supply chain visibility play in managing demand volatility and regional market dynamics in India?
Digital supply chain visibility is critical in India, where demand is highly regional, seasonality is pronounced, and logistics constraints can shift rapidly.
At Shree Cement, planning operates across multiple horizons. Annual planning focuses on capacity, network footprint and medium-term demand. Monthly S&OP aligns demand, production and logistics, while daily scheduling drives execution-level decisions on despatch, sourcing and prioritisation.
As digital maturity increases, this structure is being augmented by central command-and-control capabilities that manage exceptions such as plant constraints, demand spikes, route disruptions and order prioritisation. Planning is also shifting from aggregated averages to granular, cost-to-serve and exception-based decision-making, improving responsiveness, lowering logistics costs and strengthening service reliability.

How prepared is the current workforce for Industry 4.0, and what reskilling strategies are proving most effective?
Workforce preparedness for Industry 4.0 is improving, though the primary challenge lies in scaling capabilities consistently across diverse roles.
The most effective approach is to define capability requirements by role and tailor enablement accordingly. Senior leadership focuses on digital literacy for governance, investment prioritisation, and value tracking. Middle management is enabled to use analytics for execution discipline and adoption. Frontline sales and service teams benefit from
mobile-first tools and KPI-driven workflows, while shop-floor and plant teams focus on data-driven operations, APC usage, maintenance discipline, safety and quality routines.
Personalised, role-based learning paths, supported by on-ground champions and a clear articulation of practical benefits, drive adoption far more effectively than generic training programmes.

Which emerging digital technologies will fundamentally reshape cement manufacturing in the next decade?
AI and GenAI are expected to have the most significant impact, particularly when combined with connected operations and disciplined processes.
Key technologies likely to reshape the sector include GenAI and agentic AI for faster root-cause analysis, knowledge access, and standardisation of best practices; industrial foundation models that learn patterns across large sensor datasets; digital twins that allow simulation of process changes before implementation; and increasingly autonomous control systems that integrate sensors, AI, and APC to maintain stability with minimal manual intervention.
Over time, this will enable more centralised monitoring and management of plant operations, supported by strong processes, training and capability-building.

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Redefining Efficiency with Digitalisation

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Professor Procyon Mukherjee discusses how as the cement industry accelerates its shift towards digitalisation, data-driven technologies are becoming the mainstay of sustainability and control across the value chain.

The cement industry, long perceived as traditional and resistant to change, is undergoing a profound transformation driven by digital technologies. As global infrastructure demand grows alongside increasing pressure to decarbonise and improve productivity, cement manufacturers are adopting data-centric tools to enhance performance across the value chain. Nowhere is this shift more impactful than in grinding, which is the energy-intensive final stage of cement production, and in the materials that make grinding more efficient: grinding media and grinding aids.

The imperative for digitalisation
Cement production accounts for roughly 7 per cent to 8 per cent of global CO2 emissions, largely due to the energy intensity of clinker production and grinding processes. Digital solutions, such as AI-driven process controls and digital twins, are helping plants improve stability, cut fuel use and reduce emissions while maintaining consistent product quality. In one deployment alongside ABB’s process controls at a Heidelberg plant in Czechia, AI tools cut fuel use by 4 per cent and emissions by 2 per cent, while also improving operational stability.
Digitalisation in cement manufacturing encompasses a suite of technologies, broadly termed as Industrial Internet of Things (IIoT), AI and machine learning, predictive analytics, cloud-based platforms, advanced process control and digital twins, each playing a role in optimising various stages of production from quarrying to despatch.

Grinding: The crucible of efficiency and cost
Of all the stages in cement production, grinding is among the most energy-intensive, historically consuming large amounts of electricity and representing a significant portion of plant operating costs. As a result, optimising grinding operations has become central to digital transformation strategies.
Modern digital systems are transforming grinding mills from mechanical workhorses into intelligent, interconnected assets. Sensors throughout the mill measure parameters such as mill load, vibration, mill speed, particle size distribution, and power consumption. This real-time data, fed into machine learning and advanced process control (APC) systems, can dynamically adjust operating conditions to maintain optimal throughput and energy usage.
For example, advanced grinding systems now predict inefficient conditions, such as impending mill overload, by continuously analysing acoustic and vibration signatures. The system can then proactively adjust clinker feed rates and grinding media distribution to sustain optimal conditions, reducing energy consumption and improving consistency.

Digital twins: Seeing grinding in the virtual world
One of the most transformative digital tools applied in cement grinding is the digital twin, which a real-time virtual replica of physical equipment and processes. By integrating sensor data and
process models, digital twins enable engineers to simulate process variations and run ‘what-if’
scenarios without disrupting actual production. These simulations support decisions on variables such as grinding media charge, mill speed and classifier settings, allowing optimisation of energy use and product fineness.
Digital twins have been used to optimise kilns and grinding circuits in plants worldwide, reducing unplanned downtime and allowing predictive maintenance to extend the life of expensive grinding assets.

Grinding media and grinding aids in a digital era
While digital technologies improve control and prediction, materials science innovations in grinding media and grinding aids have become equally crucial for achieving performance gains.
Grinding media, which comprise the balls or cylinders inside mills, directly influence the efficiency of clinker comminution. Traditionally composed of high-chrome cast iron or forged steel, grinding media account for nearly a quarter of global grinding media consumption by application, with efficiency improvements translating directly to lower energy intensity.
Recent advancements include ceramic and hybrid media that combine hardness and toughness to reduce wear and energy losses. For example, manufacturers such as Sanxin New Materials in China and Tosoh Corporation in Japan have developed sub-nano and zirconia media with exceptional wear resistance. Other innovations include smart media embedded with sensors to monitor wear, temperature, and impact forces in real time, enabling predictive maintenance and optimal media replacement scheduling. These digitally-enabled media solutions can increase grinding efficiency by as much as 15 per cent.
Complementing grinding media are grinding aids, which are chemical additives that improve mill throughput and reduce energy consumption by altering the surface properties of particles, trapping air, and preventing re-agglomeration. Technology leaders like SIKA AG and GCP Applied Technologies have invested in tailored grinding aids compatible with AI-driven dosing platforms that automatically adjust additive concentrations based on real-time mill conditions. Trials in South America reported throughput improvements nearing 19 per cent when integrating such digital assistive dosing with process control systems.
The integration of grinding media data and digital dosing of grinding aids moves the mill closer to a self-optimising system, where AI not only predicts media wear or energy losses but prescribes optimal interventions through automated dosing and operational adjustments.

Global case studies in digital adoption
Several cement companies around the world exemplify digital transformation in practice.
Heidelberg Materials has deployed digital twin technologies across global plants, achieving up to 15 per cent increases in production efficiency and 20 per cent reductions in energy consumption by leveraging real-time analytics and predictive algorithms.
Holcim’s Siggenthal plant in Switzerland piloted AI controllers that autonomously adjusted kiln operations, boosting throughput while reducing specific energy consumption and emissions.
Cemex, through its AI and predictive maintenance initiatives, improved kiln availability and reduced maintenance costs by predicting failures before they occurred. Global efforts also include AI process optimisation initiatives to reduce energy consumption and environmental impact.

Challenges and the road ahead
Despite these advances, digitalisation in cement grinding faces challenges. Legacy equipment may lack sensor readiness, requiring retrofits and edge-cloud connectivity upgrades. Data governance and integration across plants and systems remains a barrier for many mid-tier producers. Yet, digital transformation statistics show momentum: more than half of cement companies have implemented IoT sensors for equipment monitoring, and digital twin adoption is growing rapidly as part of broader Industry 4.0 strategies.
Furthermore, as digital systems mature, they increasingly support sustainability goals: reduced energy use, optimised media consumption and lower greenhouse gas emissions. By embedding intelligence into grinding circuits and material inputs like grinding aids, cement manufacturers can strike a balance between efficiency and environmental stewardship.
Conclusion
Digitalisation is not merely an add-on to cement manufacturing. It is reshaping the competitive and sustainability landscape of an industry often perceived as inertia-bound. With grinding representing a nexus of energy intensity and cost, digital technologies from sensor networks and predictive analytics to digital twins offer new levers of control. When paired with innovations in grinding media and grinding aids, particularly those with embedded digital capabilities, plants can achieve unprecedented gains in efficiency, predictability and performance.
For global cement producers aiming to reduce costs and carbon footprints simultaneously, the future belongs to those who harness digital intelligence not just to monitor operations, but to optimise and evolve them continuously.

About the author:
Professor Procyon Mukherjee, ex-CPO Lafarge-Holcim India, ex-President Hindalco, ex-VP Supply Chain Novelis Europe,
has been an industry leader in logistics, procurement, operations and supply chain management. His career spans 38 years starting from Philips, Alcan Inc (Indian Aluminum Company), Hindalco, Novelis and Holcim. He authored the book, ‘The Search for Value in Supply Chains’. He serves now as Visiting Professor in SP Jain Global, SIOM and as the Adjunct Professor at SBUP. He advises leading Global Firms including Consulting firms on SCM and Industrial Leadership and is a subject matter expert in aluminum and cement. An Alumnus of IIM Calcutta and Jadavpur University, he has completed the LH Senior Leadership Programme at IVEY Academy at Western University, Canada.

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