Connect with us

Concrete

Blended Cement Grinding: Energy Intake and Fineness

Published

on

Shares

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

Concrete

India Sets Up First Carbon Capture Testbeds for Cement Industry

Five CCU testbeds launched to decarbonise cement production

Published

on

By

Shares



The Department of Science and Technology (DST) recently unveiled a pioneering national initiative: five Carbon Capture and Utilisation (CCU) testbeds in the cement sector, forming a first-of-its-kind research and innovation cluster to combat industrial carbon emissions.
This is a significant step towards India’s Climate Action for fostering National Determined Contributions (NDCs) targets and to achieve net zero decarbonisation pathways for Industry Transition., towards the Government’s goal to achieve a carbon-neutral economy by 2070.
Carbon Capture Utilisation (CCU) holds significant importance in hard-to-abate sectors like Cement, Steel, Power, Oil &Natural Gas, Chemicals & Fertilizers in reducing emissions by capturing carbon dioxide from industrial processes and converting it to value add products such as synthetic fuels, Urea, Soda, Ash, chemicals, food grade CO2 or concrete aggregates. CCU provides a feasible pathway for these tough to decarbonise industries to lower their carbon footprint and move towards achieving Net Zero Goals while continuing their operations efficiently. DST has taken major strides in fostering R&D in the CCUS domain.
Concrete is vital for India’s economy and the Cement industry being one of the main hard-to-abate sectors, is committed to align with the national decarbonisation commitments. New technologies to decarbonise emission intensity of the cement sector would play a key role in achieving of national net zero targets.
Recognizing the critical need for decarbonising the Cement sector, the Energy and Sustainable Technology (CEST) Division of Department launched a unique call for mobilising Academia-Industry Consortia proposals for deployment of Carbon Capture Utilisation (CCU) in Cement Sector. This Special call envisaged to develop and deploy innovative CCU Test bed in Cement Sector with thrust on Developing CO2 capture + CO2 Utilisation integrated unit in an Industrial set up through an innovative Public Private Partnership (PPP) funding model.
As a unique initiative and one of its first kind in India, DST has approved setting up of five CCU testbeds for translational R&D, to be set up in Academia-Industry collaboration under this significant initiative of DST in PPP mode, engaging with premier research laboratories as knowledge partners and top Cement companies as the industry partner.
On the occasion of National Technology Day celebrations, on May 11, 2025 the 5 CCU Cement Test beds were announced and grants had been handed over to the Test bed teams by the Chief Guest, Union Minister of State (Independent Charge) for Science and Technology; Earth Sciences and Minister of State for PMO, Department of Atomic Energy, Department of Space, Personnel, Public Grievances and Pensions, Dr Jitendra Singh in the presence of Secretary DST Prof. Abhay Karandikar.
The five testbeds are not just academic experiments — they are collaborative industrial pilot projects bringing together India’s top research institutions and leading cement manufacturers under a unique Public-Private Partnership (PPP) model. Each testbed addresses a different facet of CCU, from cutting-edge catalysis to vacuum-based gas separation.
The outcomes of this innovative initiative will not only showcase the pathways of decarbonisation towards Net zero goals through CCU route in cement sector, but should also be a critical confidence building measure for potential stakeholders to uptake the deployed CCU technology for further scale up and commercialisation.
It is envisioned that through continuous research and innovation under these test beds in developing innovative catalysts, materials, electrolyser technology, reactors, and electronics, the cost of Green Cement via the deployed CCU technology in Cement Sector may considerably be made more sustainable.
Secretary DBT Dr Rajesh Gokhale, Dr Ajai Choudhary, Co-Founder HCL, Dr. Rajesh Pathak, Secretary, TDB, Dr Anita Gupta Head CEST, DST and Dr Neelima Alam, Associate Head, DST were also present at the programme organized at Dr Ambedkar International Centre, New Delhi.

Continue Reading

Concrete

JK Lakshmi Adopts EVs to Cut Emissions in Logistics

Electric vehicles deployed between JK Puram and Kalol units

Published

on

By

Shares



JK Lakshmi Cement, a key player in the Indian cement industry, has announced the deployment of electric vehicles (EVs) in its logistics operations. This move, made in partnership with SwitchLabs Automobiles, will see EVs transporting goods between the JK Puram Plant in Sirohi, Rajasthan, and the Kalol Grinding Unit in Gujarat.
The announcement follows a successful pilot project that showcased measurable reductions in carbon emissions while maintaining efficiency. Building on this, the company is scaling up EV integration to enhance sustainability across its supply chain.
“Sustainability is integral to our vision at JK Lakshmi Cement. Our collaboration with SwitchLabs Automobiles reflects our continued focus on driving innovation in our logistics operations while taking responsibility for our environmental footprint. This initiative positions us as a leader in transforming the cement sector’s logistics landscape,” said Arun Shukla, President & Director, JK Lakshmi Cement.
This deployment marks a significant step in aligning with India’s push for greener transport infrastructure. By embracing clean mobility, JK Lakshmi Cement is setting an example for the industry, demonstrating that environmental responsibility can go hand in hand with operational efficiency.
The company continues to embed sustainability into its operations as part of a broader goal to reduce its carbon footprint. This initiative adds to its vision of building a more sustainable and eco-friendly future.
JK Lakshmi Cement, part of the 135-year-old JK Organisation, began operations in 1982 and has grown to become a recognised name in Indian cement. With a presence across Northern, Western, and Eastern India, the company has a cement capacity of 16.5 MTPA, with a target to reach 30 MT by 2030. Its product range includes ready-mix concrete, gypsum plaster, wall putty, and autoclaved aerated fly ash blocks.

Continue Reading

Concrete

Holcim UK drives sustainable construction

Published

on

By

Shares



Holcim UK has released a report titled ‘Making Sustainable Construction a Reality,’ outlining its five-fold commitment to a greener future. The company aims to focus on decarbonisation, circular economy principles, smarter building methods, community engagement, and integrating nature. Based on a survey of 2,000 people, only 41 per cent felt urban spaces in the UK are sustainably built. A significant majority (82 per cent) advocated for more green spaces, 69 per cent called for government leadership in sustainability, and 54 per cent saw businesses as key players. Additionally, 80 per cent of respondents stressed the need for greater transparency from companies regarding their environmental practices.

Image source:holcim

Continue Reading

Trending News

SUBSCRIBE TO THE NEWSLETTER

 

Don't miss out on valuable insights and opportunities to connect with like minded professionals.

 


    This will close in 0 seconds