Solid waste management in non-ferrous industries in India

This paper highlights the production capacity, type and quantity of solid wastes generated, their chemical composition and treatment/disposal options for the Indian aluminium, copper lead and zinc industries. Red mud, spent pot lining (SPL), fly ash from aluminium industries; scrap, slag, dross, reverts, slime, flue dust, mill scales, sludge etc. from copper industries; zinc tailing, slag, leach residue, jarosite residue, β-cake, etc. from zinc industries and BF slag, flue dust, ISF slag etc. from lead industries are the major solid waste generated from the process. Common practices of waste management in these industries are through recycling and recovering the metal values and dumping. Owing to the presence of the toxic elements in some of the solid wastes cause environmental degradation. Stringent pollution control rules are being enacted and implemented as a result of which all the metal producing industries in organised sector are now taking care of the environment and waste management related problems, but pollution from unorganized lead units are the major cause of concern. Permissible limits of toxic constituents in zinc based secondaries and threshold zinc concentration for both indigenous and imported raw material were worked out at National Metallurgical Laboratory (NML) and based on these results a recommendation to MOEF, Government of India was made to specify the permissible limits for the import of zinc secondaries. An overview of the attempts made to recycle/recover metal values and production of value added products, at NML are also mentioned in the text.