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Cement Additives for Improved Grinding Efficiency

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In a two-part series, Consultant and Advisor Shreesh A Khadilkar, discusses how advanced additive formulations allow for customised, high-performance and niche cements.

Cement additives are chemicals (inorganic and organic) added in small amounts (0.01 per cent to 0.2 per cent by weight) during cement grinding. Their main job? Reduce agglomeration, prevent pack-set, and keep the mill running smoother. Thus, these additions primarily improve, mill thru-puts, achieve lower clinker factor in blended cements PPC/PSC/PCC. Additionally, these additives improve concrete performance of cements or even for specific special premium cements with special USPs like lower setting times or for reduced water permeability in the resultant cement mortars and concrete (water repellent /permeation resistant cements), corrosion resistance etc
The Cement additives are materials which could be further differentiated as:

Grinding aids

  • Bottlenecks in cement grinding capacity, such materials can enhance throughputs
  • Low specific electrical energy consumption during cement grinding
  • Reduce “Pack set” problem and improve powder flowability

Quality improvers

  • Opportunity for further clinker factor reduction
  • Solution for delayed cement setting or strength development issues at early or later ages.
  • Others: Materials which are used for specific special cements with niche properties as discussed in the subsequent pages.

When cement additives are used as grinding aids or quality improvers, in general the additives reduce the inter-particle forces; reduce coating over grinding media and mill internals. Due to creation of like charges on cement particles, there is decreased agglomeration, much improved flowability, higher generation of fines better dispersion of particles in separator feed and reduction of mill filling level (decrease of residence time). However, in VRM grinding; actions need to be taken to have stable bed formation on the table.
It has been reported in literature and also substantiated by a number of detailed evaluations of different cement additive formulations in market, that the cement additive formulations are a combination of different chemical compounds, composed of:
1. Accelerator/s for the hydration reaction of cements which are dependent on the acceleration effect desired in mortar compressive strengths at early or later ages, the choice of the materials is also dependent on clinker quality and blending components (flyash / slag) or a mix of both.
2. Water reducer / workability / wet-ability enhancer, which would show impact on the resultant cement mortars and concrete. Some of the compounds (retarders) like polysaccharide derivatives, gluconates etc., show an initial retarding action towards hydration which result in reducing the water requirements for the cements thus act as water reducers, or it could be some appropriate polymeric molecules which show improved wet-ability and reduce water demand. These are selected based on the mineral component and type of Cements (PPC/PSC /PCC).
3. Grinding aids: Compounds that work as Grinding Aid i.e. which would enhance Mill thru-put on one hand as well as would increase the early strengths due to the higher fines generation/ or activation of cement components. These compounds could be like alkanol-amines such as TIPA, DEIPA, TEA etc. or could be compounds like glycols and other poly-ols, depending on whether it is OPC or PPC or PSC or PCC manufacture.

Mechanism of action
1. Reduce Agglomeration ; Cement particles get electrostatically charged during grinding; stick together ; form “flocs” ; block mill efficiency ; waste energy. Grinding aid molecules adsorb onto particle surfaces ; neutralise charge ; prevent re-agglomeration.
2. Improve Powder Flowability; Adsorbed molecules create a lubricating layer; particles slide past each other easier ; better mill throughput ; less “dead zone” buildup.
;Also reduces caking on mill liners, diaphragms, and separator screens ; less downtime for cleaning.
3. Enhance Grinding Efficiency (Finer Product Faster) ; By preventing agglomeration, particles stay dispersed ; more surface area exposed to grinding media ? finer grind achieved with same energy input ; Or: same fineness achieved with less energy ; huge savings.

Example:

  • Without aid ? 3500 cm²/g Blaine needs 40 kWh/ton
  • With use of optimum grinding aid ? same fineness at 32 kWh/ton ? 20 per cent energy savings

4. Reduce Pack Set and Silo Caking, Grinding aids (GA) inhibit hydration of free lime (CaO) during storage ,  prevents premature hardening or “pack set” in silos. , especially critical in humid climates or with high free lime clinker.

It may be stated here that overdosing of GA , can cause: – Foaming in mill (especially with glycols) ? reduces grinding efficiency, retardation of cement setting (especially with amines/acids), odor issues (in indoor mills) – Corrosion of mill components (if acidic aids used improperly)
The best practice to optimise use of GA is , Start with 0.02 per cent to 0.05 per cent dosage , test fineness, flow, and set time , adjust up/down. Due to static charge of particles, the sample may stick to the sides of sampler pipe and so sampling need to be properly done.
Depending on type of Cements i.e. OPC, PPC, PSC, PCC, the grinding aids combinations need to be optimised, a typical Poly carboxylate ether also could be a part of the combo grinding aids

Cement additives for niche properties of the Cement in Concrete.
The cement additives can also be tailor made to create specific niche properties in Cements, OPC, PPC, PSC and PCC to create premium or special brands. The special niche properties of the cement being its additional USP of such cement products, and are useful for customers to build a durable concrete structure with increased service life.
Such properties could be:

  • Additives for improved Concrete performance of Cements, High early strength in PPC/PSC/PCC, much reduced water demand in cement, cements with improved slump retentivity in concrete, self-compacting, self levelling in concrete, cements with improved adhesion property of the cement mortar
  • Water repellence / water proofing, permeability resistance in Mortars and Concrete.
  • Biocidal cement
  • Photo catalytic cements
  • Cements with negligible ASR reactions etc.

Additives for cements for improved concrete performance
High early strengths: Use of Accelerators. These are chemical compounds which enhance the degree of hydration of cement. These can include setting or hardening accelerators depending on whether their action occurs in the plastic or hardened state respectively. Thus, the setting accelerators reduce the setting time, whereas the hardening accelerators increase the early age strengths. The setting accelerators act during the initial minutes of the cement hydration, whereas the hardening accelerators act mainly during the initial days of hydration.
Chloride salts are the best in class. However, use of chloride salts as hardening accelerators are strongly discouraged for their action in promoting the corrosion of rebar, thus, chloride-free accelerators are preferred. The hardening accelerators could be combinations of compounds like nitrate, nitrite and thiocyanate salts of alkali or alkaline earth metals or thiosulphate, formate, and alkanol amines depending on the cement types.
However, especially in blended Cements (PPC/PSC/PCC the increased early strengths invariably decrease the 28 Day Strengths. These aspects lead to creating combo additives along with organic polymers to achieve improved early strengths as well as either same or marginally improved 28 Days strengths with reduced clinker factor in the blended cement, special OPC with reduced admixture requirements. With use of appropriate combination of inorganic and organic additives we could create an OPC with substantially reduced water demand or improved slump retentivity. Use of such an OPC would show exceptional concrete performance in high grade concretes as it would exhibit lower admixture requirements in High Grade Concretes.
PPC with OPC like Properties: With the above concept we could have a PPC, having higher percentage flyash, with a combo cement additive which would have with concrete performance similar to OPC in say M40/M50 concrete. Such a PPC would produce a high-strength PPC concrete (= 60 MPa @ 28d) + Improved Workability, Durability and Sustainability.
Another interesting aspect could also be of using Ultrafine fine flyash /ultrafine slags as additions in OPC/PPC/PSC for achieving lower clinker factor as well as to achieve improved later age strengths with or without a combo cement additive.
The initial adhesion property at sites of especially PPC/PSC/PCC based mortars can be improved through use of appropriate organic polymers addition during the manufacture of these cements. Such Cements would have a better adhesion property for plastering/brick bonding etc., as it has much lower rebound loss of their Mortars in such applications.
It is needless to mention here that with use of additives, we could also have cement with viscosity modifying cement additives, for self-compaction and self-leveling concrete performance.
Use of Phosphogypsum retards the setting time of cements, we can use additive different additive combos to overcome retardation and improve the 1 day strengths of the cements and concretes.

The concluding part of this article will appear in the next issue of ICR.

About the author:
Shreesh Khadilkar, Consultant & Advisor, Former Director Quality & Product Development, ACC, a seasoned 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.

Economy & Market

Smart Pumping for Rock Blasting

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SEEPEX introduces BN pumps with Smart Joint Access (SJA) to improve efficiency, reliability, and inspection speed in demanding rock blasting operations.
Designed for abrasive and chemical media, the solution supports precise dosing, reduced downtime, and enhanced operational safety.

SEEPEX has introduced BN pumps with Smart Joint Access (SJA), engineered for the reliable and precise transfer of abrasive, corrosive, and chemical media in mining and construction. Designed for rock blasting, the pump features a large inspection opening for quick joint checks, a compact footprint for mobile or skid-mounted installations, and flexible drive and material options for consistent performance and uptime.

“Operators can inspect joints quickly and rely on precise pumping of shear-sensitive and abrasive emulsions,” said Magalie Levray, Global Business Development Manager Mining at SEEPEX. “This is particularly critical in rock blasting, where every borehole counts for productivity.” Industry Context

Rock blasting is essential for extracting hard rock and shaping safe excavation profiles in mining and construction. Accurate and consistent loading of explosive emulsions ensures controlled fragmentation, protects personnel, and maximizes productivity. Even minor deviations in pumping can cause delays or reduce product quality. BN pumps with SJA support routine maintenance and pre-operation checks by allowing fast verification of joint integrity, enabling more efficient operations.

Always Inspection Ready

Smart Joint Access is designed for inspection-friendly operations. The large inspection opening in the suction housing provides direct access to both joints, enabling rapid pre-operation checks while maintaining high operational reliability. Technicians can assess joint condition quickly, supporting continuous, reliable operation.

Key Features

  • Compact Footprint: Fits truck-mounted mobile units, skid-mounted systems, and factory installations.
  • Flexible Drive Options: Compact hydraulic drive or electric drive configurations.
  • Hydraulic Efficiency: Low-displacement design reduces oil requirements and supports low total cost of ownership.
  • Equal Wall Stator Design: Ensures high-pressure performance in a compact footprint.
  • Material Flexibility: Stainless steel or steel housings, chrome-plated rotors, and stators in NBR, EPDM, or FKM.

Operators benefit from shorter inspection cycles, reliable dosing, seamless integration, and fast delivery through framework agreements, helping to maintain uptime in critical rock blasting processes.

Applications – Optimized for Rock Blasting

BN pumps with SJA are designed for mining, tunneling, quarrying, civil works, dam construction, and other sectors requiring precise handling of abrasive or chemical media. They provide robust performance while enabling fast, reliable inspection and maintenance.With SJA, operators can quickly access both joints without disassembly, ensuring emulsions are transferred accurately and consistently. This reduces downtime, preserves product integrity, and supports uniform dosing across multiple bore holes.

With the Smart Joint Access inspection opening, operators can quickly access and assess the condition of both joints without disassembly, enabling immediate verification of pump readiness prior to blast hole loading. This allows operators to confirm that emulsions are transferred accurately and consistently, protecting personnel, minimizing product degradation, and maintaining uniform dosing across multiple bore holes.

The combination of equal wall stator design, compact integration, flexible drives, and progressive cavity pump technology ensures continuous, reliable operation even in space-limited, high-pressure environments.

From Inspection to Operation

A leading explosives provider implemented BN pumps with SJA in open pit and underground operations. By replacing legacy pumps, inspection cycles were significantly shortened, allowing crews to complete pre-operation checks and return mobile units to productive work faster. Direct joint access through SJA enabled immediate verification, consistent emulsion dosing, and reduced downtime caused by joint-related deviations.

“The inspection opening gives immediate confidence that each joint is secure before proceeding to bore holes,” said a site technician. “It allows us to act quickly, keeping blasting schedules on track.”

Framework agreements ensured rapid pump supply and minimal downtime, supporting multi-site operations across continents

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Concrete

Digital process control is transforming grinding

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Satish Maheshwari, Chief Manufacturing Officer, Shree Cement, delves into how digital intelligence is transforming cement grinding into a predictive, stable, and energy-efficient operation.

Grinding sits at the heart of cement manufacturing, accounting for the largest share of electrical energy consumption. In this interview, Satish Maheshwari, Chief Manufacturing Officer, Shree Cement, explains how advanced grinding technologies, data-driven optimisation and process intelligence are transforming mill performance, reducing power consumption and supporting the industry’s decarbonisation goals.

How has the grinding process evolved in Indian cement plants to meet rising efficiency and sustainability expectations?
Over the past decade, Indian cement plants have seen a clear evolution in grinding technology, moving from conventional open-circuit ball mills to high-efficiency closed-circuit systems, Roller Press–Ball Mill combinations and Vertical Roller Mills (VRMs). This shift has been supported by advances in separator design, improved wear-resistant materials, and the growing use of digital process automation. As a result, grinding units today operate as highly controlled manufacturing systems where real-time data, process intelligence and efficient separation work together to deliver stable and predictable performance.
From a sustainability perspective, these developments directly reduce specific power consumption, improve equipment reliability and lower the carbon footprint per tonne of cement produced.

How critical is grinding optimisation in reducing specific power consumption across ball mills and VRMs?
Grinding is the largest consumer of electrical energy in a cement plant, which makes optimisation one of the most effective levers for improving energy efficiency. In ball mill systems, optimisation through correct media selection, charge design, diaphragm configuration, ventilation management and separator tuning can typically deliver power savings of 5 per cent to 8 per cent. In VRMs, fine-tuning airflow balance, grinding pressure, nozzle ring settings, and circulating load can unlock energy reductions in the range of 8 per cent to 12 per cent. Across both systems, sustained operation under stable conditions is critical. Consistency in mill loading and operating parameters improves quality control, reduces wear, and enables long-term energy efficiency, making stability a key operational KPI.

What challenges arise in maintaining consistent cement quality when using alternative raw materials and blended compositions?
The increased use of alternative raw materials and supplementary cementitious materials (SCM) introduces variability in chemistry, moisture, hardness, and loss on ignition. This variability makes it more challenging to maintain consistent fineness, particle size distribution, throughput and downstream performance parameters such as setting time, strength development and workability.
As clinker substitution levels rise, grinding precision becomes increasingly important. Even small improvements in consistency enable higher SCM utilisation without compromising cement performance.
Addressing these challenges requires stronger feed homogenisation, real-time quality monitoring and dynamic adjustment of grinding parameters so that output quality remains stable despite changing input characteristics.

How is digital process control changing the way grinding performance is optimised?
Digital process control is transforming grinding from an operator-dependent activity into a predictive, model-driven operation. Technologies such as online particle size and residue analysers, AI-based optimisation platforms, digital twins for VRMs and Roller Press systems, and advanced process control solutions are redefining how performance is managed.
At the same time, workforce roles are evolving. Operators are increasingly focused on interpreting data trends through digital dashboards and responding proactively rather than relying on manual interventions. Together, these tools improve mill stability, enable faster response to disturbances, maintain consistent fineness, and reduce specific energy consumption while minimising manual effort.

How do you see grinding technologies supporting the industry’s low-clinker and decarbonisation goals?
Modern grinding technologies are central to the industry’s decarbonisation efforts. They enable higher incorporation of SCMs such as fly ash, slag, and limestone, improve particle fineness and reactivity, and reduce overall power consumption. Efficient grinding makes it possible to maintain consistent cement quality at lower clinker factors. Every improvement in energy intensity and particle engineering directly contributes to lower CO2 emissions.
As India moves toward low-carbon construction, precision grinding will remain a foundational capability for delivering sustainable, high-performance cement aligned with national and global climate objectives.

How much potential does grinding optimisation hold for immediate energy
and cost savings?
The potential for near-term savings is substantial. Without major capital investment, most plants can achieve 5 per cent to 15 per cent power reduction through measures such as improving separator efficiency, optimising ventilation, refining media grading, and fine-tuning operating parameters.
With continued capacity expansion across India, advanced optimisation tools will help ensure that productivity gains are not matched by proportional increases in energy demand. Given current power costs, this translates into direct and measurable financial benefits, making grinding optimisation one of the fastest-payback operational initiatives available to cement manufacturers today.

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Concrete

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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