Concrete

Blended Cement Grinding: Energy Intake and Fineness

Published

4 years ago

August 11, 2022

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ICR delves into the nuances of the grinding processes to understand its impact on energy consumption, quality of output and technology as well as the methodology of producing green cement.

The early adopters of the cement grinding process involved extracted clinker from the clinker tank and transported it to the cement mill hopper by belt conveyors, where a measured quantity of clinker and gypsum was fed into a closed-circuit ball mill and OPC was produced through inter-grinding and blending of 95 per cent clinker with 5 per cent gypsum.
The initial problem was coarseness, as 20 per cent over 100-micron diameter was part of the ground cement. Today with advancement of technology the fineness has been improved (3200 gm/square cm) by adopting specialised steel in the grinding equipment, together with use of grinding media, steel balls where material fed through the mill is crushed by impact and ground by attrition between the balls. The grinding media are usually made of high-chromium steel. Fineness is a controlled parameter for cement to ensure better hydration and strength development. Ground cement is then stored in a water-proof concrete silo for packing.

Making Cement Green
The rise of blended cement, starting from use of fly ash (30 per cent to 35 per cent) in PCC and blast furnace slag (65 per cent to 70 per cent) in slag-based cement, as an additive with clinker, together with 5 per cent gypsum, made the introduction of green cement as a better environment friendly product. The use of fly ash or blast furnace slag with clinker created avenues for commercial consumption of coal-fed pPower plant waste (fly ash) and steel blast furnace waste (slag) leading to the green cement that used 60 per cent of clinker in PCC and 35 per cent clinker in slag based cement.
This development has seen progressive increase of both fly ash and slag in the ground cement as well as in concrete, where fly ash or ground slag is added to OPC at the concreting stage. Such processes had enormous logistics challenges and in India the adoption of such a process during concreting is less prevalent.
Grinding a mixture of clinker with the fly ash or slag, together with gypsum has implications of cost stemming from use of electricity for grinding and landed cost of all inputs for the grinding process. Cement grinding is the single biggest consumer of electricity in the entire manufacturing process of cement, the rest is in the grinding of limestone in the crushers and in the fuel mills for grinding fuel used in the clinkerisation process. Finished grinding may consume 25-50 kWh/t cement, depending on the feed material grindability, additives used, plant design and especially the required cement fineness.
The grinding process absorbs more energy due to the losses attributable to heat generated during grinding, friction wear, sound noise and vibration. Less than 20 per cent of energy absorbed is reckoned to be converted to useful grinding: the bulk is lost as heat, noise, equipment wear and vibration. For ball mills, only 3 to 6 per cent of absorbed energy is utilised in surface production, the heat generated can increase mill temperature to more than 120⁰ C and causes excessive gypsum dehydration and media coating, if mill ventilation is poor.

Understanding the Process
There are four types of grinding mills in use today are:
Ball Mill (BM): Predominant despite higher energy consumption partly because of historical reasons but partly also because it still offers considerable advantages over other mills, often operating with roller press for pre-grinding or in combined grinding.
Vertical Roller Mill (VRM): Gained popularity in the last decade due to lower energy consumption and higher capacity, with relatively few plants in service.
Roller Press (RP): A more recent choice especially after the advent of the V-separator and improved roller life, offers the lowest energy consumption but even few plants in service.
Horizontal Mill (HM): A very few in service and found mainly in companies related to the
mill developer.

The chart below shows the relative power consumption for the different types of grinding process:

The implications of higher cost in installation, maintenance, operating cost, availability and quality of ground cement, makes the BM still the most common type of technology used, while VRM scores on electrical consumption.
The role of grinding media cannot be ignored in this entire process of grinding. The BM is a horizontal cylinder partly filled with steel balls (or occasionally other shapes) that rotates on its axis, imparting a tumbling and cascading action to the balls. Material fed through the mill is crushed by impact and ground by attrition between the balls. The grinding media are usually made of high-chromium steel. The smaller grades are occasionally cylindrical (‘pebs’) rather than spherical. There exists a speed of rotation (the ‘critical speed’) at which the contents of the mill would simply ride over the roof of the mill due to centrifugal action. The critical speed (rpm) is given by: nC = 42.29/√d, where d is the internal diameter in metres. A BM is normally operated at around 75 per cent of critical speed, so a mill with diameter 5 metres will turn at around 14 rpm.
The mill is usually divided into at least two chambers (although this depends upon feed input size – mills including a roller press are mostly single-chambered), allowing the use of different sizes of grinding media. Large balls are used at the inlet, to crush clinker nodules (which can be over 25 mm in diameter). Ball diameter here is in the range 60–80 mm. In a two-chamber mill, the media in the second chamber are typically in the range 15–40 mm, although media down to 5 mm are sometimes encountered. As a general rule, the size of media has to match the size of material being ground: large media can’t produce the ultra-fine particles required in the finished cement, but small media can’t break large clinker particles. Mills with as many as four chambers, allowing a tight segregation of media sizes, were once used, but this is now becoming rare.

-Procyon Mukherjee

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Concrete

PROMECON introduces infrared-based tertiary air measurement system for cement kilns

Published

4 hours ago

May 20, 2026

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The new solution promisescontinuous, real-time tertiary air flow measurement in cement plant operations.

PROMECON GmbH has launched the McON IR Compact, an infrared-based measuring system designed to deliver continuous, real-time tertiary air flow measurement in cement plant operations. The system addresses the longstanding process control challenge of accurate tertiary air monitoring under extreme kiln conditions. It uses patented infrared time-of-flight measurement technology that operates without calibration or maintenance intervention.

Precise tertiary air measurement is a critical requirement for stable rotary kiln operation. The McON IR Compact is engineered to function reliably at temperatures up to 1,200°C and in the presence of abrasive clinker dust. Its vector-based digital measurement architecture ensures that readings remain unaffected by swirl, dust deposits or drift. Due to these conditions conventional measurement systems in pyroprocess environments are often compromised.

The system is fully non-intrusive and requires no K-factors, recalibration or periodic readjustment, enabling years of uninterrupted operation. This design directly supports plant availability and reduces the maintenance overhead typically associated with process instrumentation in high-temperature zones.

PROMECON has deployed the McON IR Compact at multiple cement facilities, including Warta Cement in Poland. Plant operators report that the system has aided in identifying blockages, optimising purging cycles for gas burners, and supplying accurate flow data for AI-based process optimisation programmes. The practical outcomes include more stable kiln operation, improved process control, and earlier detection of process disturbances.

On the energy side, real-time tertiary air data enables reduction in induced draft fan load and helps flatten process oscillations across the pyroprocess. This translates to lower fuel and energy consumption, fewer unplanned shutdowns, and a measurable reduction in NOx peaks. This directly reflects on the downstream cost implications for plants operating SCR or SNCR systems for emissions compliance.

Concrete

Adani Group To Set Up Cement Factory In Madhya Pradesh

Chief Minister Mohan Yadav inaugurates plant in Guna

Published

2 days ago

May 18, 2026

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Adani Group (Adani) will set up a cement factory in Madhya Pradesh, the chief minister of the state announced after an inauguration ceremony in Guna. The chief minister, Mohan Yadav, described the occasion as a historic day for the state and said the project will strengthen industrial capacity. The event was presented as a milestone in efforts to broaden manufacturing and attract large-scale investment. Officials said the facility will add to regional production capability and support related industries.

State officials outlined that the plant will enhance supply chains for construction and infrastructure projects across the region. The company will bring technical expertise and logistical resources to the site, with government agencies coordinating approvals and land allocation. Local suppliers and service providers will benefit from increased demand, and training initiatives will be developed to build workforce readiness. Officials indicated that the project complements broader plans to modernise industrial clusters in the state.

The state administration said it has facilitated clearances and infrastructure support to accelerate implementation. Local officials have coordinated with the company to ensure connectivity and utilities are in place ahead of commissioning. The chief minister emphasised that collaboration between private investors and the government aims to create sustainable economic growth. Community outreach programmes will address local concerns and establish grievance mechanisms as construction proceeds.

Officials said the inauguration in Guna marks a new phase in the state industrial story and will serve as a reference for future investments. Administrators noted that close monitoring and periodic reviews will guide timely execution and adherence to environmental and safety norms. The government affirmed its commitment to facilitating responsible industrial expansion while ensuring benefits reach local communities. Stakeholders will continue discussions on supply chain integration and long term maintenance arrangements.

Concrete

Railways Boost Cement Movement by 170 Per Cent and Eye Fly Ash

New container wagons cut costs and speed turnaround

Published

2 days ago

May 18, 2026

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Indian Railways has recorded a 170 per cent rise in cement movement in the last four months after reforms launched in November to promote rail based bulk cement logistics. The Union Railway Minister, Ashwini Vaishnaw, reviewed the container sector reforms and their implementation and described the shift as improving plant to market efficiency. The reforms introduced customised bulk cement tank containers and a bulk cement terminal policy to support multimodal handling and door to door solutions.

The new system has simplified loading and unloading by enabling mechanised operations and by reducing package losses compared with bagged cement transport. Since cement can move directly from manufacturing centres to consumption centres in standardised tank containers compatible with Ready Mix Concrete machines, two stages of handling have been eliminated and material loss has been reduced. The standard shape of the containers facilitates faster turnaround and lowers logistics costs for suppliers and builders.

The improved freight turnaround is helping to lower the delivered cost of cement, which can ease pressure on housing costs for the poor and middle class and support affordable construction. The reform is said to be environment friendly as dust generation during material transfer has fallen and fuel consumption and emissions have reduced due to modal shift from road to rail. The Make in India tank containers are designed for seamless movement between train and trailer and to enable efficient door to door movement while cutting congestion on roads.

Building on the cement reforms, officials were urged to tap the fly ash transportation market to convert industrial waste into national wealth. The minister noted that nearly 300 million metric tonnes (mn t) of fly ash is produced in the country while only about 13 million t is transported by rail and asked officials to substantially increase Railways share to serve brick kilns, cement industries and construction sites. Wider utilisation of fly ash should reduce pollution, promote recycling and lower construction material costs while strengthening sustainable freight movement across infrastructure sectors.