Cement Energy and Environment

Storage, Handling a~d Feeding System for Hazardous Wastes in !Indian Cement Industry Ram Chandra J~ao, Rabindra Singh and Ashutosh Saxena National Council for Cement and Building Materials Introduction: Coal is the primary fuel used in Indian Cement industry and the industry is making efforts to reduce the carbon foot print by resorting to use of alternate fuels including hazardous waste . Methods adopted by cement industry are use of Alternate Fuels and Raw materials (AFRs) such as spent wash from sugar industry, scrapped tyres, Common Effluent Treatment Plant (CETP) sludge, Municipal Solid Wastes [MSW], plastic waste, paint sludge from automobile sector, bio-fuels , petroleum refinery sludge, pesticide sludges, etc. The co-processing technologies in existence in developed countries are based on established I tried and tested technology. Therefore, there is adequate international operating exp19riences to prove that the best practices are available and the technology is feasible. To overcome initial technical barriers of non-availability of proven technology indigenously and design of most appropriate systems suitable for Indian plants, it is imperative to carry out detailed project studies for development of required system design and guidelines for identification of proven technologies. The use of alternate fuels including waste materials containing combustible value by cement industry primarily began for economic reasons, it eventually proved to be more beneficial in relation to ecological objectives. Some of hazardous combustible wastes used in the overseas cement plants are waste oils, plastics, refinery sludge, sewage sludge, ETP sludge, etc. To achieve a complete thermal destruction, sufficient temperature, oxygen supply, residence time and mixing conditions are needed. An important criterion for environmentally sound destruction and irreversible transformation is to achieve a sufficient destruction efficiency (DE) or destruction and removal efficiency (ORE). A ORE value greater than 99.9999 % is required for POPs especially dioxins and furans. System design for co-processing It is obvious that cement plants located in different parts of the country would have different options to select waste(s) best suited for them. In some locations it may be feasible to use two alternate fuels. The plant may decide to install facilities for both types and use simultaneously or use one as a standby. However, most plants would opt for one type of alternate fuel and equip themselves to use it. The most preferred option would be to get alternate fuel in ready to use form at the plant site. Any alternate fuel handling installation comprises of following phases . • Storage (Manual or automatic) • Extraction • Conveying • Feeding • Firing system Some waste fuels are hazardous - they can catch fire easily and or explode or emit obnoxious gases. Their handling can therefore be dangerous as they are hazardous to health. Storage of Hazardous waste A very important aspect of using hazardous waste is its storage. Problems connected with storing and handling of oil and coal has been sorted out as they have been the principal fuels in cement and many other industries. Storage of hazardous waste should be for as brief a period as possible and in accordance with the permit and regu lation. Recommended maximum storage times are: a. 10 days for waste mixtures, and hazardous wastes; b. 21 days for hazardous waste impregnated substrates; 14