Improving waste management
waste management

Improving waste management

Co-processing in cement kiln is a scientific, proven and established technology for disposing hazardous and other non-recyclable waste in an environmentally sustainable way. Due to its advantages, cement kiln stands apart among the different methods of waste disposal like incineration, waste to energy and land filling.

Indian cement industry is rated as one of the best performing industries across various industrial sectors in terms of energy efficiency, quality control, environmental sustainability and adaptability to new technology. Waste from various industries and residential areas are being utilised by the cement industry as alternative fuels and raw materials (AFR). As cement manufacturing process itself supports the environmentally sustainable waste utilisation due to availability of high temperature in the kiln, hence it is acting as backbone for waste generating industries. There are many associations and institutions that are working to support the cement industry to enhance the waste utilisation and sustainable manufacturing for clean and green India.

India is one of the world’s fastest growing economies showing resilient to external factors. The economies of scale have predominantly taken over the narrative around resource use leaving principles of circularity and resource efficiency in the background The long-term growth perspective is high but with the rise in resource demand. The country’s natural resources like limestone and coal for that matter are under strain and there is critical need for resource efficiency improvement. Circular economy is emerging approach, which can take the country to newer heights without straining the resource supply.

Circular economy looked towards the elimination of any kind of waste in the market. It defines waste to any kind of under utilisation of resources or assets rather than its interpretation as junk material. The

challenge to put circular consumption into practice can be addressed by 3R principle that is based on reduce, recycle and reuse.

There are five streams of circular economy models i.e. (i) circular supply chain; provide renewable energy, bio-based or fully recyclable input material to replace single-lifecycle inputs, (ii) recovery and recycling; recover useful resources/energy out of disposed products or by-products, (iii) product life extension; extend working lifecycle of products and components by repairing, upgrading and reselling, (iv) sharing platform; enable increased utilisation rate of products by making possible shared use/access/ownership, (v) product as a service; offer product access and retain ownership to internalise benefits of circular resource productivity. The cement industry has been considered as one of the pillar of growth for any nation Thermal substitution rate (TSR) It is part replacement of conventional fuel by alternative fuels in terms of thermal energy requirement and is calculated as percentage of heat supplied by alternative fuel from the total heat requirement for pyro-processing in a cement plant. Percent TSR has improved to four now as compared to a dismal one percent only three to four years back. Cement plants have adopted technologies to meet the new emission norms for Particulate Matter (PM) and NOx emissions.

Tilman Weishart

Contribution to circular economy

Cement industrys’ contribution to circular economy is primarily under two heads i.e. (i) circular supply chain, (ii) recovery and recycling. Figure 1 indicates that how the cement industry is contributing in circular economy and sustainable manufacturing

Recovery and recycling

It has been established that different types of wastes/by products of other industries available worldwide can be utilised as alternative fuels and raw materials for cement production. Moreover, production of blended cements, composite cements and utilising performance improvers in cement also support circular economy. Use of fly ash and granulated blast furnace slag (GBFS) in the production of blended cements i.e. Portland Pozzolana Cement (PPC) and Portland Slag Cement (PSC) is also beneficial for conservation of natural resources, lowering in clinker factor in cement and reduction in CO2emissions along with environmental sustainability. Increased use of alternate fuel identified as one of the key levers to reduce emissions in the Indian cement industry. India’s cement demand is expected to reach 550 to 600 million tonnes per annum (MTPA) by 2025.

Alternative fuels: The cement manufacturers are consuming all possible alternative fuels (AFs) like refuse-derived fuel (RDF), industrial plastic, biomass, tyre chips, waste generated by pharmaceutical industry,paint industry, agro industry, paper industry, chemical industry, etc.

Table 1 indicates that waste utilisation as fuel in India is still reasonable good considering high cement production capacity but still has huge potential to achieve high TSR. The number can of the Indian cement industry can go up by 5.5 per cent with overall TSR of around 9.5 per cent by utilising 90 per cent of single use plastic as fuel and replacing conventional fuel like coal and petcoke. This will provide a steady path to achieve 25 per cent TSR by year 2025 and will encourage the circular economy in near future.Increased use of alternate fuel identified as one of the key levers to reduce emissions in the Indian cement industry. India’s cement demand is expected to reach 550 to 600 million tonnes per annum (MTPA) by 2025 and the target set is 25 percent of TSR by 2025. Let us see what are the resources available.

Waste availability Municipal Solid waste (MSW) is a heterogeneous mixture, includes all types biodegradable, inert, recyclable, Electrical & electronic, pesticides and hazardous wastes. Currently, of the estimated 62 million tonnes of MSW generated annually by 377 million people in urban areas, more than 80 per cent is disposed at dump yards in an unhygienic manner leading to problems of health and environmental degradation. Considering the projected waste generation of 140 million tonnes by 2025, the requirement of land for setting up landfill for 15 years (considering 10 meter high waste pile) could be as high as approx. 50 thousand hectares of precious land, which is equivalent to size of Chennai. Refused derived fuel (RDF) which is generated from MSW can be utilised as an effective alternate fuel in cement plants, which can result in reduction of waste going to land fill and ensures sustainable way of waste management in the country.

Industrial waste

Spent Pot lining (SPL) is a waste generated in the aluminium smelting industry. SPL is having a heat content in the range of 4000 - 5000 kCal/kg, which can be used in cement plant as an alternative

fuel. SPL is subjected to close regulatory control including the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal . Hazardous properties of SPL are :

  • Toxic fluoride and cyanide compounds that are leachable in water.

  • Corrosive - exhibiting high pH due to alkali metals and oxides.

  • Reactive with water - producing inflammable, toxic and explosive gases.

Currently SPL is managed in secured storage and filling (SLF) sites, hence this waste is stored on site for years together, posing huge environment risk, in particular to the groundwater and health of people.

Cement plants can support SPL disposal in an environmentally sustainable manner through coprocessing in cement kiln. The availability of the SPL is high particularly in the states of Chhattisgarh and Odisha.

Biomass

Biomass is organic matter derived from living, or recently living organisms. It is renewable, widely available, carbonneutral and has the potential to provide significant employment in the rural areas. Commonly used materials includerice and and paddy husk, sawdust, and food industry waste.

Tyre waste

Tyre waste is another source of alternative fuels.In India as per all India Tyre Manufacturing Association (ATMA) about 0.83 million tonnes of used tyres are generated annually in 2011-2012. The average calorific value is around 6,500 kcal/ kg of waste makes it superior alternate fuels to use in cement co-processing.The target set is very ambitious yet achievable.

Source: A paper published by CII and Shakti Sustainable Energy Foundation

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