Concrete

Pyroprocessing – Paving the Way for a More Sustainable Approach

Published

3 years ago

December 13, 2022

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Optimising pyroprocessing in cement production is the key to reducing carbon emissions along with use of alternative fuels, raw materials and advanced technology. ICR delves into how energy efficient systems can make the Indian cement industry achieve its net zero target, and lead the world by its example.

Cement is a key ingredient for building everything – from roads to buildings and more. There are six major stages to the cement manufacturing process:

raw material extraction or quarry
raw material grinding, preparation and blending
preheating
kiln stage
cooling and final grinding
packaging or shipping

The major raw materials for cement, i.e., limestone, clay, sand, etc. are quarried and crushed into smaller pieces of about six inches. They are further broken down into smaller pieces of three inches. The crushed raw ingredients are made ready for the cement-making process in the kiln by combining them with additives and grinding them to ensure a fine homogenous mixture. The composition of cement is proportioned here depending on the desired properties of the cement. Generally, limestone is 80 per cent of the composition, and the remaining 20 per cent is clay. In the cement plant, the raw mix is dried (moisture content reduced to less than 1 per cent); heavy wheel-type rollers and rotating tables blend the raw mix and then the roller crushes it to a fine powder to be stored in silos and fed to the kiln.
A preheating chamber consists of a series of cyclones that utilise hot gases produced from the kiln in order to reduce energy consumption and make the cement-making process more environment-friendly. The raw materials are passed through here and turned into oxides to be burned in the kiln.
In the kiln stage, the principal stage of cement making process, clinker is produced from the raw mix fed to the kiln through a series of chemical reactions. This process of clinker formation in the kiln at high temperature is known as pyroprocessing.
After exiting the kiln, the clinker is rapidly cooled down from 2000°C to 100°C-200°C by passing air over it. At this stage, different additives are combined with the clinker to be ground in order to produce the final product, cement. Gypsum is added to the clinker at this stage and ground with it. This gives cement its most important property, its compressive strength.
The heat produced by the clinker is circulated back to the kiln to save energy. The last stage of making cement is the final grinding process. In the cement plant, there are rotating drums fitted with steel balls. Clinker, after being cooled, is transferred to these rotating drums and ground into such a fine powder. Cement is conveyed from grinding mills to silos (large storage tanks) where it is packed and shipped in bulk quantities.

The Kiln Phase of Cement Manufacturing
Cement kilns are used for the pyroprocessing stage of manufacture of portland and other types of hydraulic cement, in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates.
Limestone is the major raw material used in the raw mix fed to the kiln. The calcination of limestone along with some additional raw materials. Once the raw mix is fed to the kiln, and gradually heated by the burning of fuel, successive chemical reactions take place as the temperature of the raw mix rises:

At a temperature of 70°C to 110°C the water or moisture content of the raw mix is evaporated to achieve a dry mix
As the temperature rises from 400oC to 600°C, the clay-like minerals are decomposed into their constituent oxides; principally SiO2 and Al2O3. dolomite (CaMg(CO3)2) decomposes to calcium carbonate (CaCO3), MgO and CO2.
When the temperature further rises to 650°C to 900°C, the calcium carbonate reacts with SiO2 to form belite (Ca2SiO4) (also known as C2S in the Cement Industry).
As the temperature reaches 900°C to 1050°C, the remaining calcium carbonate decomposes to calcium oxide (CaO) and CO2.
Upon achieving maximum temperature of 1300°C to 1450°C, partial (20 per cent to 30 per cent) takes place, and belite reacts with calcium oxide to form alite (Ca3O·SiO4) (also known as C3S in the Cement Industry).

At the peak temperature of 1450°C, the reaction is complete. The partial melting causes the material to aggregate into lumps or nodules, typically of diameter 1–10 mm. This is called clinker. The hot clinker next falls into a cooler which recovers most of its heat, and cools the clinker to around 100 °C, at which temperature it can be conveniently conveyed to storage.
As cited by Dr SB Hegde in his paper, Significance of Liquid Content in Clinker, the most important clinker phase is C3S (alite), which requires the presence of liquid for its formation. In the absence of liquid, alite formation is extremely slow and it would render clinkering impossible. This fact also explains why alite is formed essentially in the burning zone, where the amount of liquid is at a maximum. To understand why alite formation requires liquid content, one must first understand the alite formation mechanism:

C2S and free CaO dissolves in the clinker melt.
Calcium ions migrate towards C2S through chemical diffusion.
C3S is formed and crystalised out of the liquid.

Without liquid phase the diffusion of Ca ions towards C2S would be extremely slow, and that of C2S almost impossible at clinkering temperature. It is important to mention that Na2O and K2O decrease the mobility of Ca ions, whereas MgO and sulphates considerably increase it. That is why addition of gypsum in the raw mix promotes alite formation.

Pyroprocessing Machinery
As one of the key roles in the cement manufacturing process, pyroprocessing solutions have been developed by multiple engineering giants in the industry to enhance and make this process efficient.

Preheaters are used in industrial dry kiln cement production plants to heat the raw mix and drive off carbon dioxide and water before it is fed into the kiln. There are three types of rotary kilns: kiln without preheater, kiln with preheater (PH), and kiln with both preheater and precalciner (PC). Kilns with PH are preferred to kilns without PH as they have lower energy consumption. For this reason, long rotary kilns without PH (long dry kilns) are being replaced over time. Thermal energy requirement is further reduced if a PH kiln is also equipped with a PC. New facilities usually include both PH and PC. A preheater (PH) is series of vertical cyclones in which the material is passed in counterflow with exhaust gases from the rotary kiln so that heat is transferred from the hot gas to the raw meal, which is therefore preheated and even partially calcined before entering the rotary kiln.
The moisture content of the raw materials determines the number of stages. Where moisture is less than 8.5 per cent, a PH kiln with 4 to 6 stages may be used. The higher the number of cyclone stages, the more the heat recovered. The energy demand of a 6-stage cyclone PH is about 60 MJ/t less than the demand of a 5-stage PH, and a 5-stage PH would save almost 90 MJ/t over a 4-stage PH.
Calciners represent a significant proportion of the fuel consumption i.e., up to 60 per cent of the total fuel consumed in the cement manufacturing process. The advancement and efficiency of a calciner, is therefore essential to overall fuel and process efficiency. Technically advanced calciners work on reducing the fuel consumption, thus, helping in reduction of NOx and carbon in the environment. Advanced calciners can be used with a variety of fuels like petroleum coke (petcoke) and anthracite and alternative fuels as well.

Pyroprocessing and Emissions
Carbon dioxide measured at NOAA’s Mauna Loa Atmospheric Baseline Observatory peaked for 2022 at 420.99 parts per million in May, an increase of 1.8 parts per million over 2021, pushing the atmosphere further into territory not seen for millions of years. Scientists at Scripps Institution of Oceanography, which maintains an independent record, calculated a similar monthly average of 420.78 parts per million, as published on Forbes.com.

Inside the kiln at the peak temperature of 1450oC, the chemical reaction of the raw mix complete, resulting in the
formation of clinker.

Carbon dioxide pollution is generated by burning fossil fuels for transportation and electrical generation, by cement manufacturing, deforestation, agriculture, and many other practices.
The Emissions Gap Report 2022 report shows that updated national pledges since COP26 – held in 2021 in Glasgow, UK – make a negligible difference to predicted 2030 emissions and that we are far from the Paris Agreement goal of limiting global warming to well below 2°C, preferably 1.5°C. Policies currently in place point to a 2.8°C temperature rise by the end of the century. Implementation of the current pledges will only reduce this to a 2.4-2.6°C temperature rise by the end of the century, for conditional and unconditional pledges respectively. The report finds that only an urgent system-wide transformation can deliver the enormous cuts needed to limit greenhouse gas emissions by 2030: 45 per cent compared with projections based on policies currently in place to get on track to 1.5°C and 30 per cent for 2°C.

The Emissions Gap Report 2022 suggests that only an urgent system-wide transformation can deliver the enormous
cuts needed to limit greenhouse gas emissions

The Indian cement industry is the second largest cement manufacturer in the world and a contributor towards the emission of carbon and other greenhouse gases. Calcination of limestone in the kiln (also known as pyroprocessing) emits the maximum carbon dioxide as a result of the chemical reaction and due to the use of fossil fuel to generate the heat in the kiln for the chemical reaction.
The industry is proactively working towards achieving Net Zero with the use of alternative fuels, raw materials and advancing its equipment in technology to achieve a higher productivity and energy efficient system that ultimately results in lower carbon generation.
Dr Hitesh Sukhwal, Deputy General Manager – Environment, Udaipur Cement Works Limited (UCWL), says, “JK Lakshmi Cement is the first organisation in the Indian Cement industry to install a Selective Non-Catalytic Resistance Equipment at their Sirohi plant for the mitigation of the oxides of nitrogen emitted during the manufacturing of cement. Subsequently at other plants of the organisation, this equipment has been installed for the mitigation of NOx emissions. As primary mitigation measures for NOx emissions, Oxy Rich, has been installed in the calciners at every manufacturing unit of the organisation with certain modifications made to suit each kiln.”
“We have taken up a target of achieving 10 per cent to 12 per cent of TSR by 2025 and up to 15 per cent by 2030. To achieve these targets, we will be installing alternative fuel feeding systems at our integrated cement plants, which are set to be executed by 2023. These alternative fuel feeding systems will be feeding both solid and liquid forms of fuels. For example, at our Durgh and Sirohi plants, both solid and liquid forms of alternative fuels and raw materials are used during pyroprocessing. At the Udaipur plant, liquid alternative fuels are being used which greatly helps in reduction of carbon emission. A major step that we have taken to curb the emission rate is to include the use of solar power in the power supply mix for the plants. Over 30 per cent renewable energy sources are being used in the energy mix of the power plants at all locations of JK Lakshmi Cement. We are tending towards the production of blended cement like Portland Slag Cement and Portland Pozzolana Cement in an effort to reduce the clinker to cement ratio. Besides the same, our grinding units are also equipped to prepare alternate cement or green cement” he adds.
Statista Report, November 2022, suggests that cement manufacturing emissions in India have experienced a steep climb in recent decades. In 2021, figures reached a high of 149 million metric tons of carbon dioxide (MtCO2). McKinsey & Company in its report, Laying the Foundation for Zero-Carbon Cement, states that it is unclear how the climate debate will unfold, reaching the goals by 2050 will be especially challenging for the cement industry, as most of its CO2 emissions result from the unavoidable chemical process known as calcination. Unlike other industries that may be further along, the development of new technologies to decarbonize cement might not be scalable for years. Nonetheless, in principle, the industry could reduce its 2017-level emissions by more than three-quarters by 2050.
Sanjay Joshi, Chief Manufacturing Officer, Nuvoco Vista, states, “Cementitious materials impact the energy consumption of cement manufacturing. These materials are easy to grind when compared to clinker which is the major constituent of cement. Thus, higher usage of cementitious materials helps in reducing energy consumption. Also, clinker usage directly involves limestone consumption as a raw material. Therefore, by using higher cementitious materials in the cement-making process, we are preserving the limestone available naturally.”
“Cement manufacturing is a closed loop wherein all raw materials from limestone mining to clinker production remain fully under controlled process parameters. The company focuses on reducing clinker consumption by increasing the blended cement ratio. Using these SCMs, Nuvoco is also aiming to save fossil fuel, along with the obvious reduction in carbon emissions. Additionally, SCMs increase the strength and durability of the product and reduce permeability,” he adds.
Rising emission of greenhouse gases, temperature and general pollution of the environment is a grave concern. It is being addressed at the global scale. The cement industry is participating actively in curbing their carbon emission rate and for the same adapting to new technologies, and alternatives to fuel and raw materials. From machinery and equipment to the formulations of blended cement, the process needs to be re-looked at to incorporate a sustainable approach to cement manufacturing while meeting the rising demands of construction and infrastructure across the globe.

-Kanika Mathur

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Concrete

The primary high-power applications are fans and mills

Published

2 days ago

October 10, 2025

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Alex Nazareth, Whole-time Director and CEO, Innomotics India, explains how plants can achieve both cost competitiveness and sustainability by lowering emissions, reducing downtime and planning for significant power savings.

As one of the most energy-intensive industries, cement manufacturing faces growing pressure to optimise power consumption, reduce emissions and improve operational reliability. Technology providers like Innomotics India are enabling this transformation by combining advanced motors, AI-driven digital solutions and intelligent monitoring systems that enhance process stability and reduce energy costs. From severe duty motors built for extreme kiln environments to DigiMine AI solutions that optimise pyro and mill operations, Alex Nazareth, Whole-time Director and CEO, Innomotics India, explains how the company is helping cement plants achieve measurable energy savings while moving closer to their sustainability goals.

How does your Energy Performance Contracting model typically reduce power consumption in cement plants—e.g., MWh saved?
Our artificial intelligence-based DigiMine AI Pyro and Mill solutions developed specifically for the cement industry, supports our customers in improving their process stability, productivity and process efficiency. In Pyro, this is achieved by optimising fuel consumption (Coal / AFR), reducing Specific Heat Consumption and reduction in emissions (CO2, SOx and NOx) through continuous monitoring of thermodynamics in pyro and recommending set-points of crucial parameters in advance for maintaining stable operations.
Within the mill, this is achieved by improving throughput, reduce energy / power consumption and maintaining stable operations on a continuous basis. Our ROI-based value proposition captures the project KPIs like reduction of coal usage, increase of AFR, reduction of specific heat consumption (Kcal / Kg), reduction of specific power consumption (KWH / tonne), reduction of emissions, etc., by a specific percentage. This gives clarity to our customers to understand the investment vis-à-vis savings and estimate the recovery time of their investment, which typically is achieved within one year of DigiMine AI Pyro and Mill solutions implementation.

What role do digitalisation and motor monitoring play in overall plant energy optimisation?
Motors are being used extensively in cement production, and their monitoring play crucial role in ensuring continuous operation of applications. The monitoring system can automatically generate alerts for any anomaly / abnormalities in motor parameters, which allows plant team to take corrective actions and avoid any major equipment damage and breakdown. The alerts help maintenance team to plan maintenance schedule and related activity efficiently. Centralised and organised data gives overview to the engineers for day-to-day activities. Cement is amongst the top energy intensive industries in comparison to other industries. Hence, it becomes critically important to optimise efficiency, productivity and up-time of plant equipment. Motor monitoring and digitalisation plays a vital role in it. Monitoring and control of multiple applications and areas
within the plant or multiple plants becomes possible with digitalisation.
Digitalisation adds a layer on top of OT systems, bringing machine and process data onto a single interface. This solves the challenges such as system silo, different communications protocol, databases and most importantly, creates a common definition and measurement to plant KPIs. Relevant stakeholders, such as engineers, head of departments and plant heads, can see accurate information, analyse it and make better decisions with appropriate timing. In doing so, plant teams can take proactive actions before machine breakdown, enable better coordination during maintenance activities while improving operational efficiency and productivity.
Further using latest technologies like Artificial Intelligence can even assist operators in running their plant with minimal requirement of human intervention, which allows operators to utilise their time in focusing on more critical topics like analysing data to identify further improvements in operation.

Which of your high-efficiency IEC low-voltage motors deliver the best energy savings for cement mills or fans?
Innomotics India offers a range of IEC-compliant low-voltage motors engineered to deliver superior performance and energy savings, particularly for applications such as cement mills, large fans, and blowers. Innomotics has the complete range of IE4 motors from 0.37kW to 1000kW to meet the demands of cement industry. The IE5 range is also available for specific requirements.

Can safe area motors operate safely and efficiently in cement kiln environments?
Yes, safe area motors are designed to operate reliably in these environments without the risk of overheating. These motors have ingress protection that prevents dust, moisture ingress and can withstand mechanical stress. These motors are available in IE3 / IE4 efficiency classes thereby ensuring lower energy consumption during continuous operation. These motors comply with relevant Indian as well as international standards.

How do your SD Severe Duty motors contribute to lower emissions and lower cost in heavy duty cement applications?
Severe duty motors enhances energy efficiency and durability in demanding cement applications, directly contributing to lower emissions and operational costs. With high-efficiency ratings (such as IE3 or better), they reduce power consumption, minimising CO2 output from energy use. Their robust design handles extreme heat, dust and vibration—common in cement environments—ensuring reliable performance and fewer energy losses.
These motors also lower the total cost of ownership by reducing downtime, maintenance and replacement frequency. Their extended service life and minimal performance degradation help cement plants meet sustainability targets, comply with emissions regulations and improve overall energy management—all while keeping production consistent and cost-effective.

What pump, fan or compressor drive upgrades have shown approximately 60 per cent energy savings in industrial settings and can be replicated in cement plants?
In the cement industry, the primary high-power applications are fans and mills. Among these, fans have the greatest potential for energy savings. Examples, the pre-heater fan, bag house fan, and cooler fans. When there are variations in airflow or the need to maintain a constant pressure in a process, using a variable speed drive (VSD) system is a more effective option for starting and controlling these fans. This adaptive approach can lead to significant energy savings. For instance, vanes and dampers can remain open while the variable frequency drive and motor system manage airflow regulation efficiently.

Concrete

We conduct regular internal energy audits

Published

2 days ago

October 10, 2025

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Shaping the future of low-carbon cement production involves integrating renewables, digitalisation and innovative technologies. Uma Suryam, SVP and Head Manufacturing – Northern Region, Nuvoco Vistas, gives us a detailed account of how.

In an industry where energy consumption can account for a significant portion of operating costs, cement manufacturers are under increasing pressure to adopt sustainable practices without compromising efficiency. Nuvoco Vistas has taken a decisive step in this direction, leveraging digitalisation, renewable energy and innovative technologies to drive energy efficiency across its operations. In this exclusive conversation, Uma Suryam, SVP and Head Manufacturing – Northern Region, Nuvoco Vistas, shares its approach to energy management, challenges of modernising brownfield plants and its long-term roadmap to align efficiency with India’s net-zero vision.

How has your company improved energy efficiency over the past five years?
Over the past five years, we have prioritised energy conservation by enhancing operational efficiency and scaling up renewable energy adoption. Through strategic fuel mix optimisation, deployment of cleaner technologies, and greater integration of renewables, we have steadily reduced our environmental footprint while meeting energy needs sustainably.
Technological upgrades across our plants have further strengthened efficiency. These include advanced process control systems, enhanced trend analysis, grinding media optimisation and the integration of solar-powered utilities. Importantly, grid integration at our key plants has delivered significant cost savings and streamlined energy management.
A notable milestone has been the expansion of our solar power capacity and Waste Heat Recovery Systems (WHRS). Our solar power capacity has grown from 1.5 MW in FY 2021–22 to 5.5 MW, while our WHRS capacity has increased from 44.7 MW to 49 MW, underscoring our commitment to sustainable energy solutions.

What technologies or practices have shown the highest energy-saving potential in cement production?
One of our most significant achievements in advancing energy efficiency has been the successful commissioning of a 132 KV Grid Integration Project, which unified three of our major manufacturing units under a single power network. This milestone, enabled by a dedicated transmission line and a state-of-the-art Line-In Line-Out (LILO) substation, has transformed our energy management and operational capabilities.
With this integration, we have substantially reduced our contract demand, eliminated power disruptions, and enhanced operational continuity. Supported by an optical fibre network for real-time communication and automation, this project stands as a testament to our innovation-led manufacturing excellence and underscores Nuvoco’s vision of building a safer, smarter, and sustainable world.

What role does digitalisation play in achieving energy efficiency in your operations?
Digitalisation plays a transformative role in driving energy efficiency across our operations. At Nuvoco, we are leveraging cutting-edge technologies and advanced digital tools to enhance productivity, optimise energy consumption and strengthen our commitment to sustainability and employee safety.
We are developing AI-enabled dashboards to optimise WHRS and kiln operations, ensuring maximum efficiency. Additionally, our advanced AI models evaluate multiple operational parameters — including fuel pricing, moisture content and energy output — to identify the most cost-effective fuel combinations in real time. These initiatives are enabling data-driven decision-making, improving operational excellence and reducing our environmental footprint.

What is your long-term strategy for aligning energy efficiency with decarbonisation goals?
As part of India’s climate action agenda, the cement sector has laid out a clear decarbonisation roadmap to achieve net-zero CO2 emissions by 2070. At Nuvoco, we view this as both a responsibility and an opportunity to redefine the future of sustainable construction. Our long-term strategy focuses on aligning energy efficiency with decarbonisation goals by embracing innovative technologies, alternative raw materials and renewable energy solutions.
We are making strategic investments to scale up solar power installations and enhance our renewable energy mix significantly by 2028. These initiatives are a key part of our broader vision to reduce Scope 2 emissions and strengthen our contribution to India’s net-zero journey, while continuing to deliver innovative and sustainable solutions to our customers.

How do you measure and benchmark energy performance across different plants?
We adopt a comprehensive approach to measure and benchmark energy performance across our plants. Key metrics include Specific Heat Consumption (kCal/kg of clinker) and Specific Power Consumption (kWh/tonne of cement), which are continuously tracked against Best Available Technology (BAT) benchmarks, industry peers and global standards such as the WBCSD-CSI and CII benchmarks.
To ensure consistency and drive improvements, we conduct regular internal energy audits, leverage real-time dashboards and implement robust KPI tracking systems. These tools enable us to compare performance across plants effectively, identify optimisation opportunities and set actionable targets for energy efficiency and sustainability.

What are the key challenges in adopting energy-efficient equipment in brownfield cement plants?
Adopting energy-efficient technologies in brownfield cement plants presents a unique set of challenges due to the constraints of working within existing infrastructure. Firstly, the high capital expenditure and relatively long payback periods often require careful evaluation before investments are made. Additionally, integrating new technologies with legacy equipment can be complex, requiring significant customisation to ensure seamless compatibility and performance.
Another major challenge is minimising production disruptions during installation. Since brownfield plants are already operational, upgrades must be planned meticulously to avoid affecting output. In many cases, space constraints in older facilities add to the difficulty of accommodating advanced equipment without compromising existing layouts.
At Nuvoco, we address these challenges through a phased implementation approach, detailed project planning and by fostering a culture of innovation and collaboration across our plants. This helps us balance operational continuity with our commitment to driving energy efficiency and sustainability.

Concrete

Enlight Metals Supplies 3,200 Tonne of Steel for Navi Mumbai Airport

The airport is set to become Asia’s largest air connectivity hub.

Published

2 days ago

October 10, 2025

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Enlight Metals has supplied 3,200 metric tonne of steel for the newly inaugurated Navi Mumbai International Airport, marking a major contribution to one of India’s largest infrastructure projects and reinforcing the company’s commitment to supporting national development.

The Navi Mumbai International Airport, developed under a Public-Private Partnership led by the Adani Group, was inaugurated today by Prime Minister Narendra Modi. The airport is set to become Asia’s largest air connectivity hub, enhancing regional connectivity, boosting economic growth, and expanding trade opportunities. Prime Minister Modi described the project as a “glimpse of Viksit Bharat,” highlighting its transformative impact on infrastructure and development in the region.

“The supply of 3,200 metric tonne of steel for this key project aligns with our focus on supporting critical infrastructure development through reliable and timely metal sourcing. Enlight Metals is committed to enhancing transparency and efficiency in the steel supply chain, contributing to projects integral to India’s growth objectives,” said Vedant Goel, Director, Enlight Metals.

Enlight Metals has implemented technology-driven solutions to strengthen supply chain efficiency, ensuring consistent availability of construction materials for large-scale projects nationwide. Its contribution to the Navi Mumbai International Airport underscores the company’s growing role in supporting India’s infrastructure development initiatives.

This milestone reflects Enlight Metals’ ongoing engagement in delivering quality materials and timely services for major national projects, further cementing its position as a reliable partner in India’s infrastructure sector