Connect with us

Environment

Filtration: Filter media selection

Published

on

Shares

An understanding of the capabilities and limitations of the fibres available for filtration is key to their successful application in any given process, writes KN Lakshmipathy.

Dust emissions are a natural result of the cement production process and the means by which they are controlled can be varied with commonly applied fabric filters. With regard to the fabrics employed in these systems, their construction is largely based on the cleaning system used.

Bag design and construction apart, the fibres employed in the filter fabric are selected on the basis of the chemical and thermal conditions in which the filter bags are to operate, along with their ability, when converted into filter fabrics, to deliver the requisite level of filtration efficiency.

Additional consideration is given to the characteristics of the dust itself and the performance level required with respect to particulate emissions and filter bag life. As one might expect, the dusts to be handled during each stage of the cement production process differ significantly and pose their own specific challenges. Equally, the gas chemistry and operating temperatures of these processes vary greatly and heavily influence the selection of the filter fabric to be used.

A thorough understanding of the process itself is vital if an informed filter fabric selection is to be made.This would include:

  • Understanding of the process.
  • Operating temperature (normal and maximum).
  • Filter velocity (air-to-cloth ratio).
  • Gas composition (O2, H2O, NOx, SO2, SO3, HCl, HF, etc).
  • Dew points – water and acid.
  • Inlet dust loading.
  • Dust characteristics.
  • Particle size distribution.
  • Performance expected (life – emissions – DP).

The specific operating parameters for any given process will vary from plant to plant so each application must be considered on a case-by-case.

Kilns / raw mills

A number of media options are available for the high temperature kiln processes. Many systems today utilise woven fibreglass filter bags which display excellent thermal resistance capability; woven glass, when laminated with an ePTFE (expanded Polytetrafluoroethylene) membrane, is able to deliver exceptional filtration efficiency and cleanability and is ideally suited to the chemical environment found in most cement kiln/raw mill systems. Continuous operation at temperatures up to 260oC is possible and, whilst it should be noted that a strong understanding of the requirements of woven glass filter bags is required in order to apply glass successfully, good practice and sound application can see filter bags in woven glass with ePTFE membrane providing a life of up to six years.

Cleaning imparts the greatest mechanical stresses on the filter media and those filter bags which experience fewer cleaning cycles invariably display a higher residual strength over longer periods of operation. Excessive dust loads naturally result in aggressive cleaning regimes. Beyond woven glass, the conditions seen in kiln/mill systems often permit the employment of high temperature polymers such as Polyimide fibre (P84«). In addition to its strong mechanical resistance properties, its ability to withstand elevated temperatures of up to 230oC on a continuous basis (gas conditions permitting) and excellent chemical resistance capability, the multi-lobal cross-sectional structure of P84 fibre increases the effective surface area of the filter media, thus allowing for a more stable dust cake to be maintained on the surface of the filter bags, in turn enhancing filtration efficiency and operational performance.

With a reduced temperature capability to the above-mentioned fabrics, both Polyphenylene Sulphide (PPS) and Homopolymer Acrylic fibre have, to a lesser extent, been applied in cement kiln processes.

Coal mills

Coal remains the fuel of choice for many cement kiln systems around the world and on-site milling of coal for kiln fuel is still a common process. Coal dust, being potentially explosive, must be processed with due care. It is possible for static electrical charge to build up on and within the filter cakes that accumulate on filter bags and such charges must be able to dissipate rapidly to limit the potential for explosion which thereby requires the filter bags and media employed in these systems to be inherently conductive. The addition of a proportion of stainless steel fibres into the fibres of a felted media and/or the use of support scrims which incorporate steel fibres can significantly enhance the conductivity of a filter fabric. As per the requirements of DIN54345-1 and DIN54345-5, filter media for use in potentially explosive environments must display a maximum resistance of 1×108 Ohms (surface and volume).

Operating temperatures in coal mill filters tend to be lower, minimising explosion risks, and typical filter media employed are Polyester and Homopolymer Acrylic or often blends of these two fibres; conductive properties can be added to a variety of filter fabrics to suitably reduce their electrical resistance.

Clinker coolers

The use of ESPs is still common for the exhausting of clinker coolers, but as with the kiln process, the use of fabric filters is on the increase. Exhaust temperatures from the cooler will typically be between 200 and 450oC and it will often be necessary to cool the gases down prior to their being cleaned in the filter. Dust loads are generally low and commonly around 10g/Nm3. A wide variety of filter fabrics are employed in clinker cooler systems, polyester, homopolymer acrylic, aramid, P84, and fibreglass, have all been applied successfully on clinker cooler systems. Attention should be given to gas velocities given the particularly abrasive nature of clinker dust.

Finish mills

The fabric filters employed on finish mills often become a bottleneck in the cement production process; with high dust loads, the filters employed on these systems are often pushed beyond their design capacity so the ability of the filter bags to perform effectively under such demands is of critical value.

Temperatures within finish mill filters are typically below 150oC with humidity being the primary gaseous concern which, with temperature, will influence the filter media options available for such systems. Polyester is commonly employed, but where levels of humidity and temperature are sufficiently high, it may be necessary to consider homopolymer acrylic or PPS fibres. Blends of polyester and acrylic are increasingly common and a variety of fluorocarbon treatments can be employed to afford the filter media enhanced water repellency, dust release and chemical resistance properties.

The use of grinding aids/agents in finish mills can cause some problems for the filters. As the dust becomes less agglomerative so conventional felts, whose efficiency is generally reliant on filter cake formation, can struggle to function effectively; as it becomes difficult to maintain a stable filter cake on the surface of the filter bags, fine particles are more able to penetrate into the structure of the filter fabric, increasing a pressure drop and leading to higher particulate emissions.

In such cases, it may be necessary to consider alternative media constructions and/or finishes better able to handle such situations. P84 fibres can again be utilised to enhance the filtration efficiency of filter fabrics and it is possible to apply a layer of such fibre to the filtration surface of a felt to assist in the maintenance of a stable filter cake. Fine and microdenier fibres have been shown to be better able to collect fine free-flowing dusts with needle felts manufactured from such fibres inhibiting the penetration of fine dust into their structure.

Whilst the selection of high performance, high quality filter media and bags can enhance fabric filter performance, a full system approach is recommended – many factors influence filter operation and minor modifications often bring about significant operational benefits and savings. Andrew Industries (India), a part of the Andrew Industries (UK) group of companies, is well-placed to provide the products and support services to meet the filtration requirements of the cement industry.

KN Lakshmipathy, is Chief Executive Officer, Andrew Industries (India). Email: lpathy@andrewindia.com

Continue Reading
Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *

Concrete

We engineer smarter systems to reduce waste

Published

on

By

Shares

Naveen Kumar Sharma, AVP – Sales and Marketing, Toshniwal Industries, talks about redefining instrumentation with customised, digitally enabled solutions engineered for harsh plant environments.

For over six decades, Toshniwal Industries has played a pioneering role in advancing process instrumentation for Indian manufacturing. In this exclusive conversation with Kanika Mathur, Naveen Kumar Sharma, AVP – Sales & Marketing, explains how the company designs kiln and grinding plant solutions tailored to the unique demands of the cement industry. As plants transition to higher AFR use and smarter automation, Toshniwal’s technologies offer greater reliability, accuracy and predictive insight.

Tell us how are your process instruments and condition monitoring system customised for cement kilns and grinding plant operations?
Toshniwal is a company with a legacy of over 65 years, and our experience has taught us that cement kilns and grinding units are fundamentally different in their operational demands. As an Indian company, we understand the unique requirements of Indian cement manufacturers. We work closely with our customers, engage deeply with their technical teams, and study operational challenges in real-time.
Based on these insights, we customise our solutions for both kiln and grinding applications. This tailoring is not just at a product level, but at a solution level—engineering design, instrumentation logic, and process optimisation. Our primary objective, for both the industry and our customers, is to reduce yield loss. Every customisation we implement is driven by this goal. We engineer smarter systems to reduce waste, improve consistency and increase plant reliability.
Ultimately, our solutions are built on an understanding that cement manufacturers require robust, practical and maintainable instruments. We design with this mindset so plants can operate more efficiently, with better control and higher profitability.

With the rising use of AFR, how do your solutions support thermal zone reliability and process time?
Our solutions are built around four core parameters: energy efficiency, yield loss reduction, product quality and environmental responsibility. These pillars drive our engineering decisions and define how our technologies support cement plants, especially as they adopt alternative fuels and raw materials (AFR).
We strongly believe in energy conservation. Every product we offer—whether for thermal monitoring, kiln control or flame optimisation—is engineered to improve energy performance. Reducing yield loss is another principle deeply embedded in our solutions, because production interruptions and material losses directly affect plant profitability and clinker quality.
We are also highly conscious of the end-product quality delivered by our customers to their markets. Consistency in burning, heat transfer, and thermal profiling directly influences clinker characteristics, and our instruments help maintain this stability.
Lastly, and most importantly, we care about the environment. We want to leave a greener world for the next generation. This mindset aligns with India’s digitalisation movement, advocated by our Prime Minister. Digital technologies are crucial for optimising AFR use, process stability, emissions and kiln efficiency. We are proud to contribute to this transition.
By optimising flame patterns, energy use, and pollution, our solutions deliver direct and indirect savings. Plants benefit from lower operational losses, reduced maintenance, and improved reliability, especially in pyroprocessing zones.

Tell us how do you address harsh environment challenges in cement plants, say dust, temperature, etc. with your sensor and monitoring?
This is a very important question because cement plants, steel plants, and power plants operate in extremely harsh environments. There are two major categories of specifications that we must respect while designing solutions: technical specifications and environmental specifications. Technical specifications relate to performance accuracy, measurement integrity, responsiveness and process safety. Environmental specifications, on the other hand, relate to high temperatures, heavy dust, humidity, vibrations and corrosive atmospheres. Our solutions are engineered to withstand both. We customise sensors, housings, mounting mechanisms and protective systems so that our instruments operate at 100 per cent functionality in harsh conditions. We ensure that the plant experiences minimal downtime from our systems. That is our engineering philosophy—solutions must work reliably in real-world environments, not just in ideal laboratory conditions.

What retrofit pathways do you offer for older cement lines to upgrade measurement and monitoring systems and how is the Indian market responding?
Every solution we provide is scalable and digitally adaptable. Technology evolves rapidly, and our offerings evolve with it. When we upgrade instruments or monitoring systems, we design them to integrate with existing plant infrastructure, so customers do not have to rebuild everything from scratch. Once our solution is installed, software upgrades or performance improvements can often be deployed without major cost. This ensures that customers continue to benefit from ongoing technological advancements. The Indian market has responded positively to this approach. Plant operators appreciate solutions that are future-ready and dynamic rather than static. Scalability helps them maintain competitiveness, extend asset life, and move toward smart manufacturing with confidence.

So how is your organisation leveraging digital technologies in your instrumentation portfolio for cement plants?
Digitalisation is at the core of every product we manufacture. We stand firmly behind the digital movement, not only because it represents efficiency, but because it is the direction in which the Indian industrial ecosystem is evolving. We deploy machine-vision technologies, advanced inline monitoring systems, and solutions capable of visualising the
inside of the furnace. These systems help reduce downtime, enable predictive asset management and provide actionable analytics to customers. All our technologies communicate seamlessly with Level 1, Level 2, and Level 3 automation. This allows integration across SCADA, DCS, ERP, and cloud ecosystems. Digitalisation for us is not an add-on—it is foundational to how our instrumentation is built.

What are your key innovation priorities to help Indian cement plant producers hit harder, higher substitution rates, lower emissions and smarter processing?
Sustainability is a national priority, and we are committed to supporting it. Our current portfolio already helps improve efficiency, reduce emissions, and support alternative fuel integration. But our innovation roadmap goes further. We are now developing specialised productivity-oriented software modules that will provide proactive alerts—not just alarms triggered after a fault has occurred. These modules will leverage artificial intelligence and machine learning to detect patterns early. The intention is to help plant teams take corrective actions ahead of time, reducing yield loss and environmental impact. Instead of informing the plant that a disruption has happened, the system will indicate that a disruption will happen, giving operators time to prevent it. We believe that within the next 12 to 18 months, we will launch these predictive solutions in combination with our instrumentation. When implemented, they will significantly improve decision-making, process stability and environmental performance across the Indian cement sector.

– Kanika Mathur

Continue Reading

Concrete

India donates 225t of cement for Myanmar earthquake relief

Published

on

By

Shares

On 23 May 2025, the Indian Navy ship UMS Myitkyina arrived at Thilawa (MITT) port carrying 225 tonnes of cement provided by the Indian government to aid post-earthquake rebuilding efforts in Myanmar. As reported by the Global Light of Myanmar, a formal handover of 4500 50kg cement bags took place that afternoon. The Yangon Region authorities managed the loading of the cement onto trucks for distribution to the earthquake-affected zones.

Continue Reading

Concrete

Reclamation of Used Oil for a Greener Future

Published

on

By

Shares

In this insightful article, KB Mathur, Founder and Director, Global Technical Services, explores how reclaiming used lubricants through advanced filtration and on-site testing can drive cost savings, enhance productivity, and support a greener industrial future. Read on to discover how oil regeneration is revolutionising sustainability in cement and core industries.

The core principle of the circular economy is to redefine the life cycle of materials and products. Unlike traditional linear models where waste from industrial production is dumped/discarded into the environment causing immense harm to the environment;the circular model seeks to keep materials literally in continuous circulation. This is achievedthrough processes cycle of reduction, regeneration, validating (testing) and reuse. Product once
validated as fit, this model ensures that products and materials are reintroduced into the production system, minimising waste. The result? Cleaner and greener manufacturing that fosters a more sustainable planet for future generations.

The current landscape of lubricants
Modern lubricants, typically derived from refined hydrocarbons, made from highly refined petroleum base stocks from crude oil. These play a critical role in maintaining the performance of machinery by reducing friction, enabling smooth operation, preventing damage and wear. However, most of these lubricants; derived from finite petroleum resources pose an environmental challenge once used and disposed of. As industries become increasingly conscious of their environmental impact, the paramount importance or focus is shifting towards reducing the carbon footprint and maximising the lifespan of lubricants; not just for environmental reasons but also to optimise operational costs.
During operations, lubricants often lose their efficacy and performance due to contamination and depletion of additives. When these oils reach their rejection limits (as they will now offer poor or bad lubrication) determined through laboratory testing, they are typically discarded contributing to environmental contamination and pollution.
But here lies an opportunity: Used lubricants can be regenerated and recharged, restoring them to their original performance level. This not only mitigates environmental pollution but also supports a circular economy by reducing waste and conserving resources.

Circular economy in lubricants
In the world of industrial machinery, lubricating oils while essential; are often misunderstood in terms of their life cycle. When oils are used in machinery, they don’t simply ‘DIE’. Instead, they become contaminated with moisture (water) and solid contaminants like dust, dirt, and wear debris. These contaminants degrade the oil’s effectiveness but do not render it completely unusable. Used lubricants can be regenerated via advanced filtration processes/systems and recharged with the use of performance enhancing additives hence restoring them. These oils are brought back to ‘As-New’ levels. This new fresher lubricating oil is formulated to carry out its specific job providing heightened lubrication and reliable performance of the assets with a view of improved machine condition. Hence, contributing to not just cost savings but leading to magnified productivity, and diminished environmental stress.

Save oil, save environment
At Global Technical Services (GTS), we specialise in the regeneration of hydraulic oils and gear oils used in plant operations. While we don’t recommend the regeneration of engine oils due to the complexity of contaminants and additives, our process ensures the continued utility of oils in other applications, offering both cost-saving and environmental benefits.

Regeneration process
Our regeneration plant employs state-of-the-art advanced contamination removal systems including fine and depth filters designed to remove dirt, wear particles, sludge, varnish, and water. Once contaminants are removed, the oil undergoes comprehensive testing to assess its physico-chemical properties and contamination levels. The test results indicate the status of the regenerated oil as compared to the fresh oil.
Depending upon the status the oil is further supplemented with high performance additives to bring it back to the desired specifications, under the guidance of an experienced lubrication technologist.
Contamination Removal ? Testing ? Additive Addition
(to be determined after testing in oil test laboratory)

The steps involved in this process are as follows:
1. Contamination removal: Using advanced filtration techniques to remove contaminants.
2. Testing: Assessing the oil’s properties to determine if it meets the required performance standards.
3. Additive addition: Based on testing results, performance-enhancing additives are added to restore the oil’s original characteristics.

On-site oil testing laboratories
The used oil from the machine passes through 5th generation fine filtration to be reclaimed as ‘New Oil’ and fit to use as per stringent industry standards.
To effectively implement circular economy principles in oil reclamation from used oil, establishing an on-site oil testing laboratory is crucial at any large plants or sites. Scientific testing methods ensure that regenerated oil meets the specifications required for optimal machine performance, making it suitable for reuse as ‘New Oil’ (within specified tolerances). Hence, it can be reused safely by reintroducing it in the machines.
The key parameters to be tested for regenerated hydraulic, gear and transmission oils (except Engine oils) include both physical and chemical characteristics of the lubricant:

  • Kinematic Viscosity
  • Flash Point
  • Total Acid Number
  • Moisture / Water Content
  • Oil Cleanliness
  • Elemental Analysis (Particulates, Additives and Contaminants)
  • Insoluble

The presence of an on-site laboratory is essential for making quick decisions; ensuring that test reports are available within 36 to 48 hours and this prevents potential mechanical issues/ failures from arising due to poor lubrication. This symbiotic and cyclic process helps not only reduce waste and conserve oil, but also contributes in achieving cost savings and playing a big role in green economy.

Conclusion
The future of industrial operations depends on sustainability, and reclaiming used lubricating oils plays a critical role in this transformation. Through 5th Generation Filtration processes, lubricants can be regenerated and restored to their original levels, contributing to both environmental preservation and economic efficiency.
What would happen if we didn’t recycle our lubricants? Let’s review the quadruple impacts as mentioned below:
1. Oil Conservation and Environmental Impact: Used lubricating oils after usage are normally burnt or sold to a vendor which can be misused leading to pollution. Regenerating oils rather than discarding prevents unnecessary waste and reduces the environmental footprint of the industry. It helps save invaluable resources, aligning with the principles of sustainability and the circular economy. All lubricating oils (except engine oils) can be regenerated and brought to the level of ‘As New Oils’.
2. Cost Reduction Impact: By extending the life of lubricants, industries can significantly cut down on operating costs associated with frequent oil changes, leading to considerable savings over time. Lubricating oils are expensive and saving of lubricants by the process of regeneration will overall be a game changer and highly economical to the core industries.
3. Timely Decisions Impact: Having an oil testing laboratory at site is of prime importance for getting test reports within 36 to 48 hours enabling quick decisions in critical matters that may
lead to complete shutdown of the invaluable asset/equipment.
4. Green Economy Impact: Oil Regeneration is a fundamental part of the green economy. Supporting industries in their efforts to reduce waste, conserve resources, and minimise pollution is ‘The Need of Our Times’.

About the author:
KB Mathur, Founder & Director, Global Technical Services, is a seasoned mechanical engineer with 56 years of experience in India’s oil industry and industrial reliability. He pioneered ‘Total Lubrication Management’ and has been serving the mining and cement sectors since 1999.

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