Concrete

The mark of a good refractory is its ability to remain inert

Published

2 years ago

October 13, 2022

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Prabhat Singh Parihar, Vice President (Technical Head), Mangrol Plant, JK Cement, talks about the challenges faced by cement plants in maintaining refractories and the important properties of refractories that ensure smooth functioning of the processes.

Explain the types of refractories you have in your manufacturing unit. What are their respective purposes?
At JK Cement’s MGR plant, the following types of refractories are used:

Acid Refractories: Any type of alumina silicate refractories (like fire bricks, alumina brick, high alumina bricks) and silica refractories are called acid refractories. Our manufacturing facilities use alumina bricks in all our kilns, PH, and coolers.
Kiln Refractory: In the kiln we use DALSINT A (70 per cent alumina and 2 per cent Fe), DALSINT B (70 per cent alumina and 2.5 per cent Fe) and alumina 40 per cent bricks in the respective kiln zones.
Purpose: Alumina bricks are especially used because these bricks resist acidic flux. Alumina bricks have good thermal stability, high refractoriness that is more than 1770oC and lower thermal conductivity resulting in less heat loss. Alumina bricks are also cost effective when compared to basic bricks.
Castable: Various grades of castable are used for better service life of the kiln inlet and outlet sectors, burner pipe and coolers. As sintered clinker is very abrasive in nature, Castables such as SiC base, mullite base and CRC- BP for burner pipe are preferred. Castables are best suited for surfaces where brick lining installation is not-possible or is not suitable, as it is easy to mould and there is no chance of falling out like bricks.
Calcium Silicate Blocks: The challenge with pyro-section is its high operating temperature, resulting in high surface heat losses to ambient surroundings. To overcome this, calcium silicate blocks are installed throughout with refractory, with increment in thickness of insulation blocks. This results in a significant decrease in surface temperature and heat loss.
Mortar: Alumina/Mullite based mortars are generally used for adhering bricks. As it also shrinks at high temperatures a limited quantity (1.5 to 2 mm) should be applied.
Ceramic Blankets / Paper / Wool: Like all materials, refractory also expands when heated. Typically, a newly installed refractory would expand anywhere between 1.5 per cent to 2 per cent initially. To avoid adding extra mechanical stress to the refractory, a gap is provided along a certain length. This is generally packed with glass-wool as it gets compressed when the refractory expands. Glass can be easily fitted in any slot or gap as it can be compressed. The dimension for the brick lining is typically 600×600 mm for castable panels, with the axial height of 1000 mm.

What are the key materials used in building a refractory lining to the kiln in your organisation?
For kiln refractory lining, a major portion consists of refractory bricks, castable for kiln inlet and outlet sector, mortar, ceramic paper, shim plate and anchors.

Refractory bricks: In a rotary kiln, the majority of the refractory type is brick refractory. Various grades of 40 per cent, 60 per cent and 70 per cent alumina bricks (DALSINT-A, B and C) are used. VDZ type bricks are generally used. Kiln lining is done by both layering and jack.
Castable are used for kiln inlet and outlet sectors to improve better service life. Since, sintered clinker is cooled just after the liquid phase as the sintered phase reaches a high temperature (1450oC) and is very abrasive in nature. Castable that is SiC base and CRC- BP is usually preferred.
Anchors: Temperature of both extremities are high, to hold castable, and provide structural strength to castable, SS-310 anchors are used. Anchors are welded and capped to prevent breakage from metallic expansion.
Ceramic Blankets / Paper / Wool: To provide expansion provision for brick lining and castable panel for kiln sector (10 to 18 panel), ceramic paper of 3 mm applied.
Mortar: Alumina/Mullite based mortars are generally used for adhering bricks. As it also shrinks at high temperature and can loosen the arch causing refractory failure, a minimum and only justified amount of mortar should be used in kiln lining.

What are the key properties of a refractory that support the cement making process?
Cement manufacturing is an energy intensive process. Burning alkaline raw materials (reactive) combined with smaller constituents of metals and abrasive raw materials at very high temperature is a major challenge. Therefore, a good refractory that can withstand high temperatures while retaining required strength and that is resistant to chemical properties of the alkaline raw materials is crucial. Besides, chemical attacks from sulphates or chlorine from the kiln feed or fuel or alternative fuels are other factors that need to be factored in.

Major refractory properties that contribute to cement manufacturing are:

Thermal properties

Refractories are materials that can withstand very high temperatures and mechanical stresses of dead load. Key parameters for considering a good refractory are its service temperature which is the maximum temperature at which refractory can withstand stresses applied to it at a given temperature.
Refractory Under Load (RUL) and Pyrometric Cone Equivalent (PCE) are defined as the most important properties of refractory, i.e., resisting or withstanding high temperature. Refractory under load can be defined as the temperature at which refractory can withstand without deformation. Pyrometric Cone Equivalent (PCU) is the temperature at which refractory starts to form an amorphous phase.
Resistance to thermal shock or spalling: As refractory is heated or cooled it tends to expand or shrink respectively a sudden cooling or heating can cause refractory to lose its strength or can dislocate its position during the heating and cooling cycle resulting in refractory failure.
Reducing heat losses: Refractories have a lower heat conductivity, thus, the heat transfer rate due to conduction is reduced.

Chemical properties
Refractory material is exposed to high temperature and reactive components of kiln feed, fuel, and alternative fuels. The major reactive components are the metal sulphates or chlorides that can penetrate through the pores of the refractory and get deposited at the core. The cold face of the refractory causes’ loss of strength of refractory material. The mark of a good refractory is its ability to remain inert.
Physical properties
Bulk density is an important property of refractories. A higher bulk density material means that it has a minimum porosity which minimises chemical attacks on the refractory.
Porosity can be defined as the percentage of open pore space in the overall volume of refractory. Pores on a refractory material, provides a site for absorption to the alkali sulphates or chlorides which get absorbed from the hot face side to under refractories and erodes and loses strength from the core of refractories. That is why a good refractory shall have a minimum apparent porosity of 0.2 per cent.
Cold crushing strength: As refractories must withstand a certain mechanical load. The load of itself and the mechanical stress generated due to expansion (radial and axial). A high cold crushing strength means that it would have less breakage while installing, with a good RUL and along comes the draw-back of brittleness
of refractory.
Thermal expansion or permanent linear change. Like all materials, refractory also expands at high temperatures. While a newly installed refractory expands to upto 2 per cent, the permanent expansion and thermal expansion shrinkage cycle deteriorates the strength and service life of the refractory.

Tell us more about the porosity and permeability of the refractory.
Porosity is the volumetric ratio occupied by pores present in refractory material. Porous material is not suitable for refractory application as it has low bulk density and low cold crushing strength.
Apparent Porosity: The ratio of the total volume of the open pores in a porous body to its bulk volume expressed as percentage, of the bulk volume is apparent porosity.
The significance of apparent porosity is as follows:

Lower the better as it influences chemical resistance.
Related to BD or compactness.
Affects cold crushing strength.
Higher the porosity, lower the thermal conductivity. This means lower heat loss because of more entrapped air inside the refractory structure. Hence, higher porosity refractory may be used to save heat loss in the area where there is lesser risk of abrasion and lower possibility of alkali penetration.
Very low porosity affects thermal shock resistance.
15 per cent to 20 per cent common value for most refractories made by machine pressing.
For hand moulded shapes 25 per cent to 35 per cent may be the range
Higher the porosity, more will be the alkali penetration. Generally, alkali salts are solidified at a temperature range between 750 to 850oC directly from vapour. Hence, a more porous refractory can be easily used in the area where the application temperature is less than 750oC.

Closed Porosity: The ratio of the total volume of the closed pores in a porous body to its bulk volume expressed as a percentage of the bulk volume is closed porosity.
True Porosity: The sum of the apparent porosity and the closed porosity is true porosity.
Permeability: It is the measure of flow of gases through pores within the refractory body, and it indicates the extent of pore linkage. Permeability of refractories gives an indication on how well the refractory will stand up to molten slag, a melt or to a gas penetration.
Permeability of refractory is directly influenced by refractory material and apparent porosity of the refractory. As the apparent porosity of the refractory increases it provides a more active site for absorption of volatile sulphates or chlorides into the refractory.

Typical cases of permeability are:

Alkali Salt Infiltration: As the pores on the refractory surface absorb the volatile metallic sulphates and chloride. They seep through refractory to core and cold face of refractory where they condense to solid form.
Anchor Corrosion: The alkali salts that seep through the castable reacts with anchors causing corrosion, hence, castable loses its structural strength causing refractory failure.

What is the maximum temperature that a refractory can withhold? How does its strength differ from ambient temperature to high temperature?
There are four key parameters for defining the maximum temperature a refractory can
withhold are:

Service Temperature: This is the temperature at which refractory can withstand without any failure or losing strength. With increase in active refractory ingredients, the refractory service temperature increases.
Refractory Under Load (RUL): It is the minimum temperature at which a sample will deform by 0.6 per cent under a constant load. Cylindrical sample that is 50 mm in diameter and 50 mm in height is tested. Constant load of 2 kg/cm2 is maintained on the specimen. The rate of temperature rise is maintained at 15oC or a minimum up to 1000oC and 8oC/min beyond that. Temperature is measured either by thermocouple or optical pyrometer. The expansion or contraction while reading is measured by a dial gauge. As a thumb rule, RUL of brick should be at least 200oC more from its application temperature.
Pyro metric Cone Equivalent (PCE): It is the temperature at which refractory material gets softened, or it indicates the range of melting point. Sample cones are made by using ~1 per cent alkali free dextrin. Standard cone (German Standard Seger cone or ASTM standard orton cone) along with sample cone are placed on a plaque at an angle of 82o inside. After that this plaque is placed inside the furnace where temperature rise is 35oC/min up to 1560oC and 2-3oC/min beyond that.
Cold Crushing Strength (CCS): In this test, the cube of a specific dimension cut from the brick sample is subjected to increasing load, until it gets crushed and the test result is reported as the value load per unit area. It indicates the adequacy of firing temperature, for shaped Refractory products, required for proper sintering and to develop the required microstructure and the quality of hydraulic or chemical bond in case of unshaped refractories. In the unshaped products, the CCS does not remain the same after heat treatment, and it decreases or increases with the temperature of heat treatment. The good cold crushing strength of shaped refractories protects them from damages during handling and from mechanical abuses in service.

PCE > RUL > Service Temperature > Operating Temperature
As a thumb rule PCE temperature is about 15 to 20oC more than RUL, whereas RUL should be about 150 to 200oC more than service temperature.
Service temperature is decided in such a manner that at any given time it is always higher than operating temperature (operating temperature + temperature increase in case of process fluctuation).
Numerous inert or non-refractory materials can decrease the service temperature as they form a new eutectic point with an active refractory compound. It is a common practice to make small panels of refractory by installing extra retainers to hold the dead weight of refractories.

Tell us about the installation and operating process of refractories in the kiln.
The lining of refractory material in the rotary kiln is almost exclusively made up of refractory bricks. Refractory castables are used in part only in the kiln inlet and outlet. The bricks work creates an arch in the kiln that is self-supporting and which correctly fits with the kiln shell.
Due to lack of anchoring, the lining must be supported during installation. Two type of bricks installation in a kiln are:
Installation with rotation of kiln – Spindle Method: The spindle method or jacking method is a classic procedure for lining rotary kilns. The bricks are placed in the lower half of the kiln, then the wall segment is supported with spindles so that the kiln can be rotated. After a quarter turn the next segment is lined and so on. The spindle method is a cost-effective method and can achieve excellent results. However, the kiln must be rotated again and again because the individual sections cannot be more than five metre in length. Moreover, the spindle method is suitable only up to a kiln diameter of 4.4 metres.
Installation without rotation of the kiln – Brick Lining Machine: A method in which the rotary kiln must not be rotated while lining (and cannot be rotated) work based on the same principle i.e., first, the lower half of the kiln is provided with the refractory bricks, because no support is required in this area and then brick lining machine will be installed for the remaining upper half area and each ring is supported by a hydraulic jack of brick lining machine until its completion.

What are the standards set for refractories in a cement kiln?
For a kiln, the following types of refractories are used: Refractory Brick, Castable and SS Anchor.
The refractory bricks for the kiln brick lining, high alumina ISO bricks of 40 per cent, 60 per cent and 70 per cent alumina are used. Abrasive resistant castables have a high service temperature and are desired such as grade- LC-60, 90 SiC and CRC as the quenching/cooling zone of the kiln handles the hot and abrasive sintered clinker. SS310 anchors are preferred over SS304 only for kiln and burner pipe.
The main standards that a refractory supplier must meet are:

Bulk Density: A very crude and crucial standard. A higher bulk density means the refractory bricks are cooked properly and have an active refractory ingredient present. Brick with low brick density indicates low active refractory ingredients.
Alumina/Active Refractory Content: Alumina content of bricks should not be less than specified value as it is the active refractory ingredient.
Iron/Ferrite: Iron content of refractory should be below 2.5 per cent as the increase in iron content decreases the PCE and RUL values.
Apparent Porosity: The value of the refractory should be kept below 0.25 as it increases the alkali salt permeability, anchor corrosion, and decreases the core crushing strength of refractory.
Cold Crushing Strength (CCS): This strength of the refractory is a must compliant property of a refractory to withhold any mechanical load that is applied to it. Typical CCS value for a fireclay with high alumina is 450kN/cm2 and 650 kN/cm2.

Refractory Under Load (RUL) for refractories it typically between 1400oC to 1500oC
Permanent Linear Change (PLC) is an expansion of a newly installed refractory. This generates an excessive mechanical load on refractory. PLC for refractory should be less than 1.5 per cent.
Pyrometric Cone Equivalent (PCE) for a refractory should be around 35 degree Orton.
Spalling Resistance are the numbers of heating and cooling cycles that a refractory can hold without any failure. Spalling resistance for refractory is desired to be above 30.
Geometry of the refractory is mostly important and no compromise can be made with it, albeit a tolerance of 1.5 to 2 mm can be considered. Same applies for the SS anchors.

What is the role of technology and automation in refractories for cement kilns?
Since the refractory work is very bulky and time consuming, lots of skilled man-hours are spent, which makes it one of the most cost and time intensive jobs. Shutdown even for a small duration of the plant is a major challenge. The introductions of new technology will help to ultimately overcome the refractory application cost and the installation time.
To overcome the above challenges, new processes/technology that are being implemented.
Brick Lining Machine: Before brick lining machine, the refractory applications required manpower for the transportation of refractory, installation of refractory and using jack for holding arch. All these procedures require a large manpower, both skilled and unskilled. In addition to that, it also takes a long time for installation.
The use of brick lining machines and portable belt conveyor, refractory materials are easily conveyed in a convenient way without any unnecessary stockpile lying around in the way of work. Since all brickwork can be done without rotation with the brick lining machine, the time lost in between tightening and loosening the jack and evacuating the manpower from the kiln while rotating is eliminated. A huge advantage is the completion of this process without the requirement of a huge manpower. A small team of skilled manpower can execute the work in a very precise manner and in a limited time.
Gunning/ShotCreting: For castable application in gunning, a batch of dry castable and binder or water are conveyed through a compressed air line to the mixing nozzle where they mix and get applied at application site. Conventional castable application requires a mandatory castable shuttering with material poured over and a vibrator needle, to set it in the right place. This makes it very time-consuming and chances of the castable not being placed properly is there which will take enormous time and manpower to rectify the application. For a shuttering that is not set properly it needs to be broken and new castable will be reapplied hence increasing cost of breaking and re-applying.
For a point place where huge quantum of castable must be applied, Gunning is preferred as it has its advantages such as:

No need of carpenter or mason or helpers for shuttering frame, making and application of castable.
Chances of castable not setting properly is eliminated.
Refractory application rate can be achieved up to 5 TPH.
Since, failure of setting occurs and application are lesser than conventional method, wastage of castable is minimum with rebound losses for gunning of are about 2 per cent.
Precast Pre-Fired Refractory: A modern and modular way for refractory application is the Precast Pre-Fired Refractory, which are pre casted to defined required geometrical shapes and can be applied simply bolting, anchoring, and hanging to roof channel support. The key advantages of the new concept are less dependency on skilled manpower, availability of refractory is already casted and only need to be installed.

What tests are employed to check the refractory for defects and at what intervals are these tests done?
There is only a limited number of methods available for a condition diagnosis of the refractory material. In practice, the following are used:

Measurement of shell temperatures.
Visual inspection from inside and outside (example: inspection of expansion joints, friction comp.)
Non-destructive measurement of residual
brick thickness
Drill holes and chiselling out of windows
Quality measurement and surveying the kiln axis

Measurement of shell temperatures: The chronological development of the maximum, average and minimum temperatures on the shell of the rotary kiln allows for conclusion to be drawn for the ratio between lining and coating build-up. Based on the velocity of the temperature changes, further development can be estimated. For example, if maximum temperature rises sharply while the average temperature remains the same or changes slightly, then this pertains to a limited, localised eruption and not overheating of the relevant kiln zone. One preferable option would be to continually check the kiln shell temperature by measuring infrared radiation.
Visual inspection from outside: Inspection or detecting peculiarities on the entire kiln plant are part of the routine task of the kiln personnel. Sudden changes in the surface colours due to increased shell temperatures are clear signs of damage in the lining. But most of the time, even more serious damage is already present. The visual diagnostic procedure therefore ranks last among potential tools, and it is primarily used to prevent further damage to machines.
The condition of the cyclone and vaulted ceilings should be checked regularly through the inspection openings in the ceilings to see if the transition between the brick masonry and the skin is flush. In addition, skin temperature should be compared to earlier measurements in order to gain information about the current refractory status.
Easily accessible part of the cooler, burner pipe or the kiln can also be inspected visually via inspection openings or kiln/cooler cameras. Such an inspection is especially suitable during sort down times as easy inspection measures.
Non-destructive measurements of residual brick thickness: The brick thickness can be measured relatively quickly using a residual thickness metre. But experience shows that generally no reliable measurement signals are provided. Residual thickness metres work with sensitive probe systems that can send and record high frequency electrical impulses. The metallic rotary kiln shell serves as a reflector to determine the residual wall thickness. This device also allows for the different electromagnetic properties of different refractory bricks and infiltration to be recorded.
Drill holes and chiselling out of windows: The residual brick height of the refractory material is determined along the rotary kiln by drilling with a brick drill (9-10 mm). The procedure and results are recorded in a drilling protocol. Brick damage is not always detected with the drilling samples. Using core drilling or chiselling of windows in critical spots, it is possible to detect crack formation or alkali filtration in addition to the residual brick height. However, the subsequent closure of the masonry is unsatisfactory with this method if the residual brick height is low.

What are the major challenges your organisation comes across with the refractory kiln?

Spalling of bricks in the burning zone: We use ISO type of bricks in the burning zone in kilns. Refractories develop the spalling because of the mismatch of thermal expansion or contraction in between hot face and cold face during heating – cooling cycle and as a result, cracks are developed in the brick. This crack propagates every time and ultimately some portion of the brick gets spelled out from the position.
Kiln bricks failure near second tyre: Due to mechanical loading as well as thermal loading, bricks failure occurs near kiln 2nd tyre area. Whenever this failure happens, then in this area brick lining is done with a manual jack method
Tip casting failure: Kiln tip casting failure occurs every 3 to 4 months of continuous running of kiln. Earlier shuttering panel was 400×400 mm as the first kiln outlet retainer was just after 400 mm from the kiln outlet. After modification, outlet retainer shifted towards inlet about 400 mm, i.e., now tip casting shuttering increased to 800×800 mm. It gives us a maximum tip casting life of about 11 months.

What innovations in the refractory sector do you expect to see in the near future that will help better it?
The two main innovations that we foresee are:

AFR friendly refractory: Due to the increasing fuel cost and focus on sustainable ways of operations, the use of alternative fuels in cement industries is essential. Though, the use of alternative fuels is limited because of the high concentration of chlorine and sulphates which are susceptible to coating formation. Therefore, coating resistant refractories that are less prone to chlorine and sulphate attacks will increase the use of alternative fuels with a good refractory life. Moreover, with the enhanced use of AFR, we require good quality AFR friendly castable near AFR feeding zones.
Insulating Bricks: Refractories with low thermal conductivity and low radiation emissivity can help to save the heat losses that ultimately leads to saving fuel, instead of increasing refractory thickness. While by increasing the refractory thickness a loss of volume in pyro-equipment may affect the production capability of the system. Therefore, we required high alumina with low thermal conductivity refractory bricks to save the radiation loss.

–Kanika Mathur

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Concrete

Smart-Tech in Cement!

Published

17 hours ago

March 11, 2025

Roshna

An invigorating discussion amongst industry experts, on digital transformation, sustainability and cybersecurity, threw interesting insights.

The cement industry is at a crucial juncture, with digital transformation, sustainability, and automation shaping its future. The panel discussion explored key points on digitalisation, sustainability and automation, emphasising the importance of a multidisciplinary approach to modern cement manufacturing.
The webinar was moderated by Dr SB Hegde, Professor, Jain College of Engineering & Technology, Hubli; and Visiting Professor, Pennsylvania State University, USA.

Speakers included:

Dr Hemantkumar Aiyer, VP & Head R&D, Nuvoco Vistas Corp
Dr Raju Goyal, Executive President, Chief Technical and Sustainability Officer,

UltraTech Cement

Dr Rizwan Sabjan, Head – Global Sales and Proposals, Process Control and Optimisation, FLSmidth Cement
Prosenjit Dutta, Director Operations, PS Digitech-HR India
Raghu Vokuda, Chief Digital Officer,

JSW Cement

Sachin Vaidya, Regional GM – Digital, Process Industries, ABB

Role of digital transformation
Dr Hegde emphasised the need for integrating emerging technologies with a multidisciplinary approach to enhance cement plant efficiency. He highlighted that “understanding of systems and how to integrate them” is essential for maximising the benefits of digital tools.
Sabjan echoed this sentiment, stressing that cement plants need to embrace a cultural and mindset shift to fully leverage digital technologies. He pointed out, “Software can do wonders for the plant, but only if the workforce understands and implements it effectively.” He warned against isolated implementations, advocating for a holistic approach where departments like OT, quality control and automation work together.

Sustainability: The road ahead
With sustainability becoming a global priority, cement manufacturers must adapt to new environmental regulations and carbon reduction goals. Dr Hegde posed a critical question: “How is the cement industry moving towards sustainability, and how can plants prepare for these changes?”
Sabjan responded by highlighting the importance of long-term planning and commitment. “Often, discussions happen, but after two months, we forget about them and restart from scratch. This approach will not work. We need a structured, goal-oriented plan with defined KPIs,” he said. Sabjan emphasised the need for a systematic approach, focusing on tangible metrics such as energy savings. “If a plant aims to improve energy efficiency by five percent, it must set this as a goal and track progress,” he suggested.
The discussion also underscored the need for strong leadership to drive digital adoption. “A motivated team and a dynamic leader can make all the difference,” Dr Hegde noted.

Enhancing durability with digital tools
Strength and durability remain critical concerns in cement production. Goyal explained, “Machine learning-based lab technologies enable predictive analysis, allowing manufacturers to forecast 28-day, 7-day, and 1-day strengths before the material leaves the mill.” He also emphasised the importance of soft sensors, which “help predict strength and optimise mix design before production.”
He elaborated on the role of XRF/XRD analysis: “These tools provide elemental and mineralogical insights, allowing for quick adjustments to raw materials and ensuring consistent quality.” Furthermore, digital twins are revolutionising cement quality optimisation. “They allow us to simulate and test mix designs before implementation, reducing errors and optimising durability.”

Cybersecurity risks in IT-OT integration
As cement plants become increasingly digitalised, cybersecurity threats pose significant risks. Vaidya expressed concern that many manufacturers underestimate cybersecurity risks. “As a technology provider, I often struggle to convince cement manufacturers of the importance of cybersecurity. Some benefits are intangible but essential for plant security.”
He outlined major threats, including malware attacks, unauthorised network access, and operational disruptions. “Preventive measures include secure data transactions, network monitoring, and regular cybersecurity training for staff to minimise insider threats,” he said.
He urged cement companies to take cybersecurity seriously: “As digital transformation advances, cybersecurity is not an option—it is a necessity. Without proper security protocols, cement plants risk cyberattacks that could halt production.”
Dr Hegde agreed, adding, “People often ignore cybersecurity until they experience financial loss. Awareness must be proactive, not reactive.”
Dutta stated, “Advanced process control (APC) is a game-changer for cement manufacturing, allowing us to stabilise operations, optimise fuel efficiency, and reduce energy consumption through real-time data insights.”
He emphasised the transformative impact of real-time data analytics and advanced process control (APC) in cement manufacturing. He highlighted that APC enables manufacturers to optimise raw mix design, fuel efficiency and kiln operations through data-driven decision-making. By continuously monitoring critical parameters, APC minimises process variations, improves stability, and reduces energy consumption, leading to cost savings and enhanced productivity. Additionally, he stressed the role of predictive maintenance in preventing equipment failures, extending machinery lifespan and minimising downtime, ultimately ensuring consistent quality and operational efficiency in cement production.

Will Indian plants become fully autonomous?
With AI, robotics and digital twins transforming global cement production, the question arises: Can Indian cement plants become fully autonomous within the next 5–10 years?
Vokuda was skeptical about complete automation in the near future. “Indian cement plants will see significant automation, but full autonomy remains unlikely within a decade. A hybrid model, combining AI-powered decision-making with human oversight, is more practical.”
He highlighted key challenges: “Unlike developed nations, India’s low labour costs may make full automation less attractive. Additionally, digital twin technology in India is still in its early stages, focusing more on process twins than asset twins.”
Another challenge is data management. “AI-ML models require vast amounts of data, which necessitates ultra-low latency networks like 5G and edge computing. We are not yet at that level of technological maturity,” he explained.
Despite these hurdles, he remains optimistic: “While full automation may take longer, the industry will continue to evolve with advancements in digital twins, real-time analytics, and AI-driven insights.”

Conclusion
Experts agree that while technology holds immense potential, its successful implementation depends on cultural shifts, strong leadership, and structured execution.
Key takeaways from the discussion include:

Integration of digital tools: Multidisciplinary collaboration is essential for successful implementation.
Sustainability goals: Defined KPIs and a long-term approach are crucial.
Quality optimisation: Machine learning, real-time analysis, and digital twins are improving cement strength and durability.
Cybersecurity: As digital transformation progresses, cement plants must prioritise cybersecurity.
Automation: While full autonomy is unlikely soon, AI and digital tools will play a growing role in decision-making.
As the industry moves forward, cement manufacturers must embrace technological advancements while ensuring resilience against cybersecurity threats and operational challenges. With the right strategies, India’s cement sector can achieve greater efficiency, sustainability, and innovation in the years to come.

ICR’s virtual panel discussion was supported by FLSmidth Cement as the Presenting Partner and ABB as the Gold Partner.

Concrete

The Science and Application of Grinding Aids

Published

17 hours ago

March 11, 2025

admin

Dr SB Hegde discusses the importance of grinding aids as essential chemical additives that enhance cement grinding efficiency, reduce energy consumption and improve overall cement quality in the concluding part of his article.

Grinding aids represent a critical segment of the cement additives market, driven by their ability to enhance grinding efficiency, reduce energy consumption, and improve cement quality. The market dynamics of grinding aids vary significantly across regions, influenced by economic growth, cement production capacities and regulatory environments.

Global market size and growth projections
The global grinding aids market was valued at approximately US $ 1.2 billion in 2023 and is expected to grow at a CAGR of 5.5 per cent from 2023 to 2030, reaching nearly US $ 1.8 billion by 2030.
This growth is fueled by the increasing focus on energy efficiency and sustainable cement production practices worldwide.
Rapid urbanisation and infrastructure development, especially in emerging economies, are major growth drivers. Cement producers are increasingly adopting grinding aids to address rising energy costs, reduce carbon footprints, and improve production efficiencies. For instance, grinding aids have been shown to lower energy consumption by up to 25 per cent, making them a cost-effective solution for plants facing energy price volatility.

Regional trends: Developed vs. developing markets

Developed markets: Europe and North America represent mature markets for grinding aids. Europe, driven by stringent environmental regulations such as the EU Emissions Trading System (EU ETS), has witnessed a steady rise in the adoption of low-VOC and eco-friendly grinding aids. Leading players in these markets emphasise sustainability and compliance with regulatory frameworks, contributing to steady demand.
In North America, the focus is on productivity enhancements in large-scale cement plants, with grinding aids used to achieve finer cement grades and support blended cement production.
Developing markets: Emerging economies in Asia-Pacific, the Middle East, and Africa exhibit the fastest growth in grinding aid adoption. The Asia-Pacific region accounted for over 40 per cent of global grinding aid consumption in 2023, with countries like India, China, and Vietnam leading the way. The rapid urbanisation, rising construction activity, and increasing cement production capacities in these regions are
driving demand.

In Africa, grinding aids are gaining traction as manufacturers focus on optimising production costs in an environment of fluctuating raw material and energy prices.

Market size and adoption rate in India
India, the world’s second-largest cement producer, offers a significant growth opportunity for grinding aids. In 2023, the grinding aids market in India was valued at US$ 150 million, with a projected growth rate of over seven per cent CAGR through 2030. The adoption rate remains relatively low at smaller plants, which prioritise cost-saving over efficiency gains. However, leading manufacturers and integrated cement plants are increasingly embracing grinding aids, particularly for blended cement production.
Blended cements, such as Portland Pozzolana Cement (PPC) and Portland Slag Cement (PSC), account for more than 70 per cent of the Indian cement market. Grinding aids tailored for fly ash and slag-blended cements are in high demand, with some products delivering up to a 15 per cent increase in mill throughput and improved early strength development.

Emerging trends

Eco-friendly formulations: The growing demand for sustainable grinding aids has prompted companies to develop low-VOC and biodegradable alternatives.
Customised solutions: Grinding aid formulations are increasingly tailored to address specific raw material challenges and production processes, such as VRMs or high-SCM cement blends.
Digitalisation: Smart dosing systems integrated with real-time mill monitoring are enabling optimised grinding aid usage, ensuring consistent performance across diverse production conditions.

Bridging the Trust Gap
For cement plant operators, the quality and performance of grinding aids often appear as a ‘black box.’ The lack of transparency in the formulation and quality checks of these additives has historically limited trust and widespread adoption. Grinding aid manufacturers must address this issue by fostering transparency and providing detailed insights into the testing and validation of their products. This would not only instill confidence but also strengthen collaboration with cement companies.
Grinding aid producers should provide robust documentation outlining the physical and chemical characteristics of their formulations, supported by consistent performance data from laboratory tests, industrial-scale trials, and third-party validations. This transparency is essential to demystify grinding aids’ performance and demonstrate their effectiveness across diverse operational conditions.

Emerging innovations in grinding aid chemistry
The path forward for grinding aid manufacturers lies in innovation. Recent research highlights the potential of hybrid formulations combining traditional amines and glycols with advanced polymeric additives like polycarboxylate ethers (PCEs). These hybrid products can address specific challenges such as improving grindability in blended cements containing fly ash or slag, where traditional additives often underperform. Nano-engineering of grinding aids, incorporating nanoparticles for optimised dispersion and enhanced hydration kinetics, represents another promising avenue.

Leveraging AI for optimisation

The integration of artificial intelligence (AI) and machine learning tools into grinding aid application systems is reshaping the cement industry. AI-driven systems enable real-time optimisation of grinding aid dosages by analysing mill performance data, such as power consumption, throughput, and particle size distribution. For example, a cement plant in Europe reported a 15 per cent reduction in specific energy consumption and a 10 per cent
increase in mill throughput using AI-optimised dosing systems. This innovation reduces operational variability and improves the predictability of grinding aid performance.

Expectations from grinding aid producers
The cement industry demands more than just products; it seeks partnerships with grinding aid manufacturers. Key expectations include:
1. Customised formulations: Tailored products designed for specific raw materials, clinker compositions, and mill configurations to maximise efficiency and performance.
2. Eco-friendly additives: Grinding aids with low volatile organic compound (VOC) emissions and biodegradable ingredients that align with the industry’s sustainability goals.
3. Comprehensive technical support: On-site training and technical services to help plant operators understand grinding aid chemistry, application techniques and performance optimisation strategies.
4. Advanced quality control systems: Transparent testing protocols, including real-time quality assurance of grinding aids delivered to cement plants. Regular reporting of performance consistency through defined KPIs like grindability index and Blaine fineness is essential.

Role of cement companies in promoting grinding aid usage
Cement producers must take an active role in promoting grinding aid adoption. Sharing success stories of energy savings, improved mill performance, and enhanced cement quality can encourage industry-wide adoption. For example, an Indian cement manufacturer recently documented a 20 per cent improvement in 28-day compressive strength and a 10 per cent reduction in energy consumption with glycol-based additives, driving interest among peers.
Moreover, collaborative initiatives between cement producers and grinding aid manufacturers, such as joint research programs and knowledge-sharing forums, could lead to significant advancements in grinding technology. Organisations like the Cement Manufacturers’ Association of India and the World Cement Association can facilitate these partnerships.

Conclusion
Grinding aids play a pivotal role in modern cement manufacturing, offering significant advantages in energy efficiency, mill productivity and cement quality. Despite their transformative potential, adoption remains inconsistent due to challenges like raw material variability, operational concerns and limited trust in product formulations. Transparency and collaboration between grinding aid producers and cement manufacturers are critical to addressing these issues and fostering broader acceptance.
Innovations in grinding aid chemistry, including hybrid formulations and nano-engineered additives, have unlocked new possibilities for enhancing grindability and hydration performance. Meanwhile, advancements in artificial intelligence and data analytics have opened avenues for real-time optimisation, ensuring precise dosing and measurable cost savings. These developments underscore the evolving synergy between technology and grinding aid applications.
Globally, the grinding aid market is poised for growth, with developed regions leading adoption and emerging economies like India offering immense potential driven by infrastructure demands. However, tapping into these opportunities requires grinding aid producers to align with industry expectations. Cement manufacturers expect customised solutions, eco-friendly formulations, technical support and transparent quality assurance processes to build trust and confidence.
The path forward demands a collaborative approach. Grinding aid producers must continue investing in research and innovation while actively engaging with the cement industry to educate stakeholders and demonstrate measurable benefits. Concurrently, the cement industry must champion adoption through case studies, knowledge sharing, and regulatory support. Together, these efforts will ensure grinding aids fulfill their promise of enabling a more efficient, sustainable, and resilient cement manufacturing sector.

References
1. Gao, J., Zhang, S., Wang, X., & Ma, B. (2011). “Effect of organic grinding aids on cement properties and the analysis via liquid chromatography-mass spectrometry.” Construction and Building Materials, 25(8), 3600–3605.
2. Amritphale, S. S., Patel, M., & Singh, R. (2017). “Grinding aids: A study on their mechanism of action in cement grinding processes.” Indian Cement Review.
3. Cembureau – The European Cement Association. “Cement grinding optimisation through grinding aids.” Industry Report, 2023.
4. Flatt, R. J., & Schober, I. (2012). “Superplasticisers and the rheology of concrete.” International Journal of Cement Chemistry, 64(4), 91–109.
5. Mejeoumov, G. G. (2007). “Improved cement quality and grinding efficiency by means of closed mill circuit modeling.” PhD Dissertation, Texas A&M University.
6. Global Cement. “Advances in grinding aids: Market trends and new technologies.” Published October 2024.
7. Statista. “Global grinding aids market size and forecast (2023-2030).” Published March 2024.
8. Pal, B. K., & Rath, P. C. (2020). “Influence of grinding aids on particle size distribution, strength, and hydration of cement.” Journal of Materials Science and Applications, 45(2), 234–246.
9. Indian Cement Review. “Emerging market scope of grinding aids in India.” Published July 2023.
10. Zhang, H., Li, X., & Zhao, Y. (2022). “The role of grinding aids in improving cement hydration kinetics.” Journal of Advanced Materials Science, 17(6), 527–540.
11. Sika AG. “Technical Report on Polycarboxylate Ether (PCE) based grinding aids.” Published 2022.
12. Cement and Concrete Research. “AI-driven optimisation in cement grinding: Case studies and industrial applications.” Volume 152, 2023.
13. Taylor, H. F. W. (1997). Cement Chemistry (2nd Edition). Thomas Telford Publishing.
14. Indian Bureau of Mines (IBM). “Market trends and challenges in cement manufacturing.” Annual Report, 2024.
15. World Cement Association. “Sustainability in grinding aids and cement additives.” Published 2024.

About the author:
Dr SB Hegde, a global cement industry leader with over 30 years of experience, is a Professor at Jain College of Engineering, India, and a Visiting Professor at Pennsylvania State University, USA. Recipient of the ‘Global Visionary’ award, Dr Hegde advises India’s think tank CSTEP on hydrogen usage in cement and consults for major cement companies. He also serves on expert panels of key industry bodies and journals globally.

Concrete

Smart sustainable solutions

Published

18 hours ago

March 11, 2025

admin

Efficient bulk material handling has always been critical for seamless production, cost reduction and environmental compliance. Kanika Mathur delves into advanced automation, smart sensors and sustainable transport solutions that are key to overcoming challenges.

The cement industry is a cornerstone of infrastructure development, contributing significantly to economic growth. However, cement production involves the handling and transportation of vast quantities of raw materials such as limestone, clay, iron ore, fly ash and gypsum, as well as the final product—cement itself. Efficient bulk material handling (BMH) systems are crucial in ensuring uninterrupted production, reducing operational costs, minimising material wastage and improving overall efficiency.

In an industry where material losses, dust emissions, and energy consumption are major concerns, advancements in bulk material handling technology are playing a vital role in optimising operations. Automated and energy-efficient bulk handling solutions, such as pneumatic conveying systems, belt conveyors and stacker-reclaimer systems, are transforming the way cement plants manage their raw materials and finished products. This article explores the key aspects of bulk material handling in the cement industry, the latest technological advancements, and the challenges and opportunities in this space.

Importance of bulk material handling
Cement manufacturing requires the continuous movement of raw materials from mines and quarries to processing plants, followed by the transportation of the finished product to storage facilities and distribution networks. Bulk material handling systems ensure that this process runs smoothly, reducing downtime and enhancing productivity.
According to the Global Cement Report (2023), inefficient material handling contributes to 5 – 10 per cent of total cement production losses in India. Additionally, poor handling practices lead to high levels of dust pollution, which is a significant environmental and health concern. With cement production in India expected to reach 500 million metric tonnes by 2025, the demand for advanced and automated material handling systems is increasing rapidly.
Jacob Jose, CEO and Managing Director, Methods India, says, “With our advanced pipe conveyors, downhill conveyors and cross-country conveyors, we have revolutionised the way cement plants transport raw materials. Our technology helps reduce operational costs, minimise environmental impact and improve energy efficiency. Over the years, we have observed a positive impact in the industry, particularly with the growing adoption of pipe conveyors and cross-country conveyors, which have proven to be more efficient and environmentally friendly alternatives to traditional transport methods.”

Key bulk material handling technologies
1. Belt conveyors: The workhorse of cement plants
Belt conveyors are one of the most widely used bulk material handling solutions in the cement industry. They transport raw materials, clinker and finished cement over long distances within the plant and to storage facilities. Modern high-capacity belt conveyors can handle loads exceeding 10,000 tonnes per hour, significantly improving efficiency.

Advantages: High efficiency, low operational costs, and reduced manual intervention.
Challenges: Belt wear and tear, spillage, and maintenance requirements.
Technological advancement: The introduction of heat-resistant and fire-retardant conveyor belts has improved durability, while sensor-based predictive maintenance systems help detect belt failures before they occur.

2. Stacker and reclaimer systems: Optimising storage and retrieval
Stackers and reclaimers are essential for managing bulk raw materials in cement plants. Stackers pile materials such as limestone, coal, and gypsum, while reclaimers retrieve them for processing. These systems ensure homogeneous blending, reducing material variability and enhancing cement quality.

Latest innovation: Automated stacker and reclaimer systems with AI-driven optimisation help maximise storage space and minimise
retrieval time.
Efficiency gains: Newer stacker-reclaimer designs allow for material recovery rates of over 90 per cent, reducing wastage and ensuring a steady feed to the production line.

3. Pneumatic conveying systems: Dust-free material transfer
Pneumatic conveying systems use air pressure or vacuum systems to move powdered and granular materials such as fly ash, cement and kiln dust through pipelines. They are particularly useful in reducing dust emissions and preventing material contamination.

Advantages: Dust-free operation, reduced environmental impact, and minimal maintenance.
Industry adoption: Many Indian cement plants are shifting from mechanical conveyors to high-pressure pneumatic conveying systems to comply with pollution control regulations set by the Central Pollution Control Board (CPCB).

4. Screw conveyors and bucket elevators: Compact and versatile solutions

Screw conveyors: Used for short-distance material movement, particularly for handling fine and powdered materials such as cement, gypsum, and pulverised coal.
Bucket elevators: Ideal for vertical material transport, commonly used for lifting raw meal, cement, and clinker to storage silos.
Technological upgrades: The introduction of wear-resistant alloy buckets and variable-speed drives has enhanced the reliability and efficiency of these systems.

Challenges in bulk material handling
Despite significant advancements, several challenges continue to hinder bulk material handling efficiency in cement plants:
1. Material spillage and dust emissions
Material spillage and dust emissions pose environmental, health, and financial challenges. Uncontrolled dust emissions from conveyors, transfer points, and storage facilities not only violate regulatory norms but also lead to material losses. Studies show that up to three per cent of bulk materials are lost due to improper handling in Indian cement plants.

Solution: Enclosed conveyors, dust suppression systems, and bag filters help reduce dust pollution.

2. High energy consumption
Bulk material handling systems consume a significant amount of energy, especially in large cement plants where materials need to be transported over long distances. According to a CII (Confederation of Indian Industry) report (2023), energy costs account for nearly 40 per cent of total production expenses in cement manufacturing.

Solution: Energy-efficient conveyor motors, regenerative braking systems, and smart automation can help reduce power consumption.

3. Wear and tear of equipment
Continuous exposure to abrasive materials like limestone and clinker leads to significant wear and tear in bulk material handling equipment, increasing maintenance costs and downtime.

Solution: The use of wear-resistant liners, ceramic-coated conveyor belts, and automated lubrication systems extends equipment life and reduces maintenance downtime.

4. Logistics and transportation bottlenecks
Moving bulk materials from cement plants to distribution centers requires an efficient logistics network. Rail and road congestion, inadequate infrastructure, and high transportation costs often result in delays and increased operational expenses.

Solution: Integrated bulk terminals and automated dispatch systems improve supply chain efficiency. The Indian government’s push for multi-modal logistics parks (MMLPs) is expected to enhance cement transportation efficiency.

Indrendra Singh Raghuwanshi, Sales Head – Cement Division, ATS Conveyors, says, “Ensuring that our systems handle diverse alternative fuels reliably is at the core of our engineering approach. Alternative fuels, such as biomass, MSW, RDF and industrial waste vary significantly in terms of composition, size, moisture content, and combustibility. All our systems are designed with flexibility and robustness to meet the unique challenges posed by these fuels while maintaining operational efficiency and safety. Also, before deployment to site, we conduct extensive testing for our equipment to ensure that they can reliably handle alternative fuels under a variety of conditions. This includes testing different fuel types, moisture levels, and feeding rates to identify any potential challenges. Our systems are then fine-tuned during the commissioning phase to ensure optimal performance in real-world conditions.”

The future is automation and digitalisation

The future of bulk material handling in the cement industry lies in automation, artificial intelligence (AI), and digital twin technologies. Leading cement manufacturers are investing in IoT-enabled bulk handling systems that provide real-time monitoring, predictive maintenance, and AI-based process optimisation.

1. Smart sensors and predictive maintenance
AI-powered sensors are now being integrated into conveyors and stackers to detect early signs of wear and tear, enabling proactive maintenance and reducing unplanned downtime.
Nishith Kundar, Co-Managing Partner, Cemtech Engineering Solutions, says, “One of our latest advancements is the introduction of drone inspection technology. Since silos are confined spaces, it is often difficult to assess their internal condition, particularly at the top. We have incorporated drone inspections for both pre-cleaning and post-cleaning assessments. Pre-cleaning drone inspections help us analyse the extent of material buildup, while post-cleaning inspections ensure that the silo has been thoroughly cleaned. This technology is also applicable to pre-heaters, allowing us to monitor internal conditions in confined spaces. By leveraging drone technology, we provide precise and efficient cleaning services, improving safety and operational efficiency.”

2. Digital twin technology
Digital twin models create a virtual replica of bulk handling systems, allowing operators to simulate various scenarios and optimise material flow before implementing changes in real time.

3. Automated Guided Vehicles (AGVs) and robotics
The adoption of AGVs and robotic material handling systems is gaining traction in cement plants for automated raw material transport, warehouse management, and truck loading/unloading.
Gaurav Gautam, Business Unit Head,
Beumer Group, says, “A major recent focus has been integrating digital monitoring tools into our equipment. These tools include condition monitoring sensors that track temperature variations, vibrations and operational anomalies in real-time. By capturing this data, plant operators can take proactive actions when conditions start deviating from normal parameters. This approach prevents sudden breakdowns and, in the long term, enhances the durability and reliability of the equipment.”
“Moving forward, digitalisation will play a key role in tackling wear and tear challenges. By increasing the number of data capture points and applying advanced analytics tools, we can gain deeper insights into equipment health and performance, ensuring a more efficient and predictive maintenance strategy,” he adds.

Conclusion
Efficient bulk material handling is the backbone of cement manufacturing, ensuring a seamless flow of raw materials and finished products while minimising environmental impact and operational costs. As India’s cement industry moves towards higher production capacities and stricter environmental norms, investing in advanced, automated and energy-efficient bulk handling solutions will be key to maintaining competitiveness.
By embracing smart technologies, automation and sustainable handling practices, cement manufacturers can enhance productivity, reduce material losses, and contribute to a greener and more efficient future for the industry.