Environmental and Waste Management (ISSN : 0971-9407) Eds. -A . Bandopadhyay, N.G. Goswami and P.R. Rao © NML, Jamshedpur - 831 007, 1998, pp. 230-241 Cobalt recovery from metallurgical wastes of zinc industry DEEPAK BHATNAGAR and A. JANCY Technology Information , Forecasting and Assessment Council (TIFAC), Dept . of Science and Technology , New Delhi - 110 016 ABSTRACT Cobalt is a metal of great strategic importance for super alloys which are used in aerospace . Cobalt is also extensively used in the manufacture of cemented carbide tools , magnetic alloys and even in ceramics as a colouring agent. During the hydro-metallurgical processfor extraction of zinc, valuable metals can also be recovered as by-products from the waste materials. Under the `Home Grown Technology Programme ' of TIFAC, a flow sheet has been developed and process optimised for cobalt recovery from met- alli rgical wastes from the zinc industry . The work was done jointly by HZL & BARC and has not only resulted in increased yield of cobalt to mop e than 60% but also improved the product quality to achieve 99.8% pure cobalt . This paper briefly outlines the modified process flowsheet consisting of washing , roasting, three stage leaching , oxalate precipita- tion and solvent extraction . Results of the market survey for cobalt metal and powder carried out as a part of the study are also enclosed. Keywords : Cobalt recovery, Wastes from zinc industry, Home grown technology programme. INTRODUCTION Cobalt occurs in nature in a widespread but dispersed form, almost exclu- sively in admixture with ores of other metals. The main potential sources for cobalt are the residues generated during the extraction of zinc. Cobalt is associated with zinc and gets concentrated as `cobalt alpha nitroso betanaphthol chelate' complex during zinc sulphate purification. This is com- monly known as `3 cake' and contains about 1 to 2% cobalt metal, besides 10- 17% zinc, 2 to 4% iron, 0.1 to 0.4% copper and 0.05 to 0.25% cadmium. 230 mn^uAFMRRFYta^A^w9YIUffihIP1^11rTF I I ng i^nnnnmonwnnrvsamrmemen^r :^n.runi. ^ca.a.l.mo.wn.m^an,m^rm n:^.^mmes^i^m®o.