Sanjay Joshi, Chief Projects and Manufacturing Officer, Nuvoco Vistas Corp, discusses the integration of alternative fuels and raw materials (AFR) into cement manufacturing.
Tell us about the alternative fuels and raw materials (AFR) used by your organisation in cement manufacturing.
The AFR usage can decrease environmental impacts, lower consumption of fossil fuels to reduce the economic impact to the cement industry. Fast depleting natural resources like limestone, increased cost of conventional fuels like pet coke and coal, have become a matter of great concern for cement industry all over the world. The high temperature and adequate retention time makes cement kilns most suitable for disposing of alternative fuels. Utilisation of AFR in the cement industry, helps in reduction of the carbon footprint, substituting consumption of fossil fuels and reducing its associated higher cost.
Nuvoco has been a pioneer in this regard, utilising substantial quantities of non-recyclable hazardous wastes, plastics, tire wastes, surplus biomass and RDF as alternative fuels since 2014. To support this initiative, Nuvoco has established comprehensive AFR storage, handling, and feeding facilities in all its plants. Additionally, Nuvoco incorporates alternative raw materials into its cement and clinker raw mix, sourced from industrial and mineral wastes in metallurgy, petrochemicals, chemicals, paper and pulp sectors. These materials include fly ash, slag, metallurgical slags, phosphogypsum and red mud, contributing to a reduced carbon footprint and decreased reliance on fossil fuels and natural conventional raw material.
What factors do you consider when selecting alternative fuels and raw materials?
The selection of AFR for usage in a cement kiln involves a thorough assessment of their potential impacts on clinker and cement manufacturing operations, product quality and the environment. Several important factors must be considered before finalising the choice of AFR.
Among these, key parameters include alkali, sulphur, chloride, trace element content, heat (calorific) value and moisture content. Regular reviews of the acceptance criteria are conducted in accordance with local regulations to ensure ongoing alignment with environmental standards and manufacturing requirements. This comprehensive evaluation
process ensures that the selected AFR optimally contributes to the cement kiln process while
minimising adverse effects on both the product and the surrounding environment.
What is the impact created on the environment by use of AFR in your organisation?
Concerning the co-processing of AFR, the cement industry is actively working towards reducing greenhouse gas emissions and preserving natural resources by incorporating a variety of AFRs in the cement kiln.
To ensure responsible handling, plants have implemented essential infrastructure, including AF storage sheds with impermeable flooring, leachate collection pits, firefighting arrangements and deodorisers, effectively mitigating the environmental impacts of AFR usage. The handling and feeding systems for alternative fuels are centrally operated from the Control Room (CCR), minimising manual interventions throughout the process. Rigorous monitoring and systematic storage procedures are in place for all wastes intended for co-processing in the cement kiln, ensuring a continuous and well-managed approach to environmental sustainability.
Have you faced any challenges or barriers when using AFR in cement production, and if so, how have you overcome them?
Certainly, when incorporating alternative fuels and raw materials, numerous challenges emerge throughout the process. These challenges span from the storage areas, where issues related to non-uniform quality of alternative fuel are encountered, to the pyro system, which has to adapt to process changes and blending during alternative fuel feeding.
In essence, the primary challenges faced in the utilisation of AFR can be succinctly summarised
as follows:
- Non-homogeneity of the waste: Wastes received by cement plants have varying chemical compositions, which initially result in operational disturbances.
- Coating, build-ups and refractory issues: The high content of chlorine and alkalis in hazardous solid waste combined with pet coke sulphur results in coating formation. Circulation of volatile salts increases and clogging arises in lower preheater cyclones and riser pipes.
- Availability of odour control system at storage sites.
- Wear and tear of equipment used for waste processing: AFR has different foreign materials like silt, glass, metal pieces so it makes heavy wear and tear of pre-processing equipment like shredder, trommel, belt conveyor, etc.
- Inhouse testing laboratory facilities not being available to check the quality of received material.
- CCR operators not being trained on operational parameters for alternative fuel usage.
- All these issues have been analysed systematically, discussed with suppliers and plant original equipment manufacturers (OEM). Some modifications have been made in the feeding system to avoid operational issues. Process related improvements are executed after discussion with OEM, which results in smooth burning of alternative fuels in the system.
How do you see the use of AFR in cement production evolving in the future, and what role do you think your company will play in this process?
In the current landscape of fuel availability and cost considerations, AFR has become integral to our fuel mix. Government initiatives have played a leading role in raising awareness about AFR usage, resulting in a notable uptick. The proliferation of pre-processing facilities, coupled with in-depth research and consultations with cement industries facilitated by catalyst bodies like Confederation of Indian Industry (CII) and Cement Manufacturers Association (CMA), has positioned co-processing as the preferred choice. This approach not only reduces production costs but also contributes significantly to resource conservation on a broader scale.
At Nuvoco Cement, we have embraced co-processing of AFR in all our integrated cement
plants. Our commitment to sustainability is evident through the adoption of new technologies aimed
at increasing the utilisation of AFR. We remain dedicated to continuously exploring and implementing innovative technologies across all our plants, demonstrating our proactive stance towards environmental responsibility.