ENVIRONMENTAL REGULATIONS AND MANAGEMENT OF SPENT POT LINING (SPL) WASTE GENERATED FROM ALUMINIUM INDUSTRY Dr. B. Sengupta Former Member Secretary Central Pollution Control Board Email: bsg161@gmail.com Presented at Round Table on use of SPL in cement co-processing organized by IIP on 22 September, 2015 at New Delhi
SPENT POT LINING (SPL) WASTE The production process of Aluminum involves conversion of Alumina to Aluminium through an electrolytic process that takes place in a pot. These pots are steel containers lined with refractory brick with an inner lining of carbon. The carbon liner is usually up to 15 inches thick and serves as the cathode in the electrolysis process that transforms aluminum ions from the molten bath to molten aluminum. Spent Pot Liner (SPL) is a by-product that is generated during this conversion. Depending on the life of the pot, SPL is chipped off from the pot for disposal and relining. SPL is hazardous in nature because of the presence of cyanide compounds, soluble fluoride and its strong affinity to combine with moisture and generate explosive gases. It is subjected to close regulatory control including the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal.
SPL GENERATION IN INDIA Parameters Units Value SPL Generated per ton of Aluminium* ton 0.025 Annual Aluminium Production in India million 1.73 (2013-14) 1 tons Annual Aluminium Production in India million 1.72 (2012-13) 2 tons Annual Aluminium Production in India million 1.67 (2011-12) 3 tons Average Annual Aluminium Production in million 1.70 India in last three years tons SPL generation per year at present million 0.042 production levels tons Total SPL generated in last three years in India million tons 0.128
HAZARDOUS WASTE MANAGEMENT RULES OF MOEF (RULE CHARACTERIZE SPL AS HAZARDOUS WASTE) pot
CREP RECOMMENDATIONS FOR SPENT POT LINE WASTE MANAGEMENT
INTERNATIONAL EXPERIENCE ON CO-PROCESSING OF SPL AS FUEL IN CEMENT KILN U.S.-generated SPL was recycled up to 79% in cement kilns in 2010. In 2009, 7449 tonnes of SPL were recycled in Australia, mostly in cement industry as AF. The heating value of SPL is 25.2 MJ/kg which is almost equal to bituminous coal. The total SPL generation in the world was about 800,000 tons in the year 2003 which implies the availability of SPL as AF. Scant literature was found in regards to environmental impact of SPL while using it as fuel in cement kiln. At 20oC the cyanide content of SPL is 0.033% and a test study showed that almost 99.9% of the cyanide is destroyed when it is used as AF in a cement kiln. Lechtenberg reported a reduction of NOX and CO2 emission while using SPL. Lechtenberg indicated that use of SPL would also be a supplement of raw materials such as silica, alumina and ferrous components. SPL has high fluorine content, and hence handling and transportation of SPL could be an issue.
CO-PROCESSING OF SPL IN CEMENT PLANT The regulatory forum under the Chairmanship of Member Secretary, GSPCB have recommended use of SPL waste in cement plant as partial fuel. Based upon recommendation of regulatory forum and task force of CPCB on co-processing, MoEF has issued draft Standards for coprocessing of waste in cement plant.
EMISSION STANDARDS FOR CO-PROCESSING OF WASTE IN CEMENT KILN
PERMISSION GRANTED BY CPCB EXPERT COMMITTEE FOR UTILIZATION OF HAZARDOUS WASTE AS A SUPPLEMENTARY RESOURCE OR FOR ENERGY RECOVERY
Minutes of the Eleventh Meeting of CPCB Expert Committee for Evaluation of proposal for utilization of Hazardous Waste under Rule 11 of the HW (M,H&T) Rules, 2008 (Sh. R.K. Garg Committee)
Minutes of the Eighth Meeting of CPCB Expert Committee for Evaluation of proposal for utilization of Hazardous Waste under Rule 11 of the HW (M,H&T) Rules, 2008 (Sh. R.K. Garg Committee)
CPCB s Bhopal Office Report on SPL usage in Cement Plant Para 17 at Page 20 Spent Pot Lining (SPL) is a waste material of Aluminum smelting industry which is generated from pot room and having a CV in the range of 4000 to 5000 which can be used in cement plant along with coal as a alternative fuel. SPL generated from M/s BALCO, Korba and trail run of co-incineration is concocted by M/s Ultra tech cement Ltd. Raipur. But due to very high bond index it can t be crushed and pulverized easily that is a big problem for using this material as AFR. The plants are not coming forward to use because of its transportation cost and initial capital investment.
CPCB S REPORT ON SPL MANAGEMENT
SPENT POT LINING MANAGEMENT AS GIVEN BY OSPCB IN CONSENT TO ESTABLISH (CTE) ORDER
RECOMMENDATION FOR CO-PROCESSING OF SPL WASTE IN CEMENT KILN Aluminium industries can approach MoEF to get amendment in the EC letter given by MoEF under EIA 2006, requesting MoEF to allow co-processing of SPL in cement kiln subject to kiln emission are within the notified standards for co-processing. Cement plant can take permission under Rule 11 of the Hazardous Waste Management Rules for utilization of energy of SPL by co-processing in cement plant and with this permission get amendment in the CTO order given by SPCB.
By DR. B. SENGUPTA Email : bsg161@gmail.com 91-9810043771