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Larger Gear Drives for Larger Vertical Roller Mills

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The global trend towards single-mill cement plants is unquestionable. With civil construction cost savings, higher throughput and lowered maintenance costs, the use of single large VRMs for cement and raw grinding is the optimal choice. The sheer size requires powerful, large-scale drive gear systems.

As operators look to increase equipment capacity, the key is to ensure long-term reliability that guarantees continuous kiln operation. There are several challenges. Whereas machine design is often the limiting factor for large ball mills and roller presses, it is the drive systems that require focus in vertical roller mills (VRMs). Placing silos before and after the kiln can reduce short interruptions in the milling processes, but long standstills caused by unexpected mechanical failures are difficult to avoid.
Reliability of VRMs depends on the drive system, the grinding system and the operational behaviour of the mill. To help lower initial cost investments aimed at preventing downtime, particular attention must be devoted to the drive system and critical grinding components, such as roller and table.
The rollers and the grinding table are exposed to high abrasive wear depending on the feed material properties, the product fineness, and the combination of rollers and table materials. At regular intervals, therefore, the table and roller wear liners must be exchanged or repaired by surface-layer welding.
Without the natural redundancy of an approach with two mills in parallel, flexibility is key. The OK™ mill has individual roller arrangements with swing-out mechanisms to facilitate maintenance or replacement of the rollers. In the case of mechanical failure, the mill can easily operate with fewer rollers. The only requirement is that the remaining rollers are uniformly distributed around the table circumference and that they are all the same size. Production can then continue, albeit at a reduced rate, to minimise operational disruption.
Impressively, the OK mill can achieve 60 to 70 per cent of nominal output with half of its rollers out of service.
“The design power of such large VRMs depends on the grindability of material. Raw mill applications require up to approximately 9,000kW, with slag and cement grinding needing up to 14,000kW. Regardless of the type, these VRMs’ drive systems need to deliver reliable torque transmission.”

Drive Systems
Conventional drive systems typically consist of a switch-gear to connect the drive motor to the electrical grid. The transformer converts the grid voltage to the motor design voltage and protects the equipment from voltage peaks. A rotor starting device and a highly flexible coupling connects the motor and gearbox.
Yet there are limits to such a system. The bevel stage in the gearbox, primarily used to redirect the rotating movement from the horizontal motor shaft into the vertical direction of the grinding table, limits power capability. For design power of up to approximately 9,000kW, this can be overcome by increasing the gear ratio in the following planetary stage, which keeps the bevel stage size within feasible dimensions. However, this does not fulfil mill requirements and a further increase in drive power requires larger dimensions, especially the diameter of the bevel wheels. This decreases the overall reliability of the drive system. Conventional gear units cannot operate VRMs with higher design power. The drive system for these applications is based on two main principles: partition of power to several drive units and elimination of the weakest element in the drive train.

Partitioning Drive Power
By separating the drive power, large VRMs can provide the required torque with multiple motors. The motors are designed either as individual drive assemblies containing their own motors, couplings and gearboxes or as small vertical motors, integrated partially into the gear casing and connected to a central toothed wheel inside the gearbox.


As a result, power distribution bevel stages are considerably smaller or, in vertical motors, completely eliminated. The drive systems are built so that they can operate with fewer motors in the case of malfunction or maintenance. This means that operation at a reduced production rate can still occur, minimising production losses during scheduled maintenance. This has the effect, however, of increasing complexity of the power distribution between the main switchgear and the motors and also increasing maintenance effort.
In addition to the main switch gear, each motor needs a separate circuit breaker and a motor control cabinet to allow operation with a reduced number of motors. In order to provide uniform torque to the common central wheels, the load and speed of each motor is synchronised by either a variable frequency converter or a highly flexible or fluid coupling. During start-up, when the mill is running at full speed with fewer motors, the timing of the connecting additional motors is essential to prevent torque peaks.

Elimination of Weakest Element
The integrated drive system in the VRM replaces the bevel stage with one vertical motor built into the gear casing. While this does not affect the power distribution, compared with the conventional system, the overall dimensions of the motor must be adapted to the available space for a bevel stage in a conventional gearbox. Otherwise, costly design changes of the mill support and foundation are required.
“The challenge with the integrated system is developing an electrical motor with the highest possible power density.”
A design study comparing different motor types showed that meeting space requirements is only possible with a synchronous motor with permanent magnet excitation and a single coil stator. To operate such type motors, variable frequency converters are necessary. Integration also makes special cooling necessary because air-cooled motors do not reach the required power density.
For example, the motor in FLSmidth MAAG® Gear’s CEM Drive includes special cooling tubes in the stator arrangement. This provides optimal flow of the cooling media and enables the use of gear lubrication oil in the motor cooling circuit.

Smart Design
Despite the challenges associated with large VRMs, there are important benefits to having an integrated drive system embedded in the design. Power distribution, such as that in a partial-load system, is not required and the number of rotating parts is kept to a minimum. The variable frequency converter allows the operator to adjust the mill table speed without time delay and to influence the grinding process individually when grinding different products in the same mill or as feed quality changes over time.
Large VRMs can help to meet the demands of a single-mill cement line by addressing the typical challenges of grinding systems. In doing so, FLSmidth’s OK mill can provide a solution for most single-mill cement lines wanting to increase their throughput.

Concrete

India Sets Up First Carbon Capture Testbeds for Cement Industry

Five CCU testbeds launched to decarbonise cement production

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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.

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Concrete

JK Lakshmi Adopts EVs to Cut Emissions in Logistics

Electric vehicles deployed between JK Puram and Kalol units

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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.

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Concrete

Holcim UK drives sustainable construction

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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

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