Recycling: An alternative to disposal -A case study on ferro-chrome slag

Abstract

In India over 1.2 lakh tonnes of ferro-chrome slag is generated every year. On an average these ferro-chrome slag contain 10-12% Cr20, as entrained metal alloys and thus in this way enormous amount of ferro-chrome is lost annually. As the slag is being pilled up for several decades at the plant site, the dump itself has become a secondary source of metal. It is likely to create ecological problem by the presence of heavy chrome metal ions in the ground water in the years to come. A pre-exploratory study was undertaken on a ferro-chrome slag sample of (IDOCL) Industrial Development Corporation Ltd., Orissa, assaying 11.2% CrO2, 3.740/, FeO and 26.95 % Si02 to study the feasibility for recovery of the values. The present paper deals with characterisation as well as beneficiation aspects of the sample. Microscopic studies on the polished section of the slag sample indicated the presence of metallic phase in the form of globules. droplets and dendrites varying in size from one micron to 40 micron. Results of gravity concentration by jigging and tabling at various sizes have been discussed. The gravity concentration at 48 mesh size by tabling produced a concentrate assaying 48.02% CrP1 and 12.63% Fe with a low recovery. The Cr:Fe ratio in the concentrate was found to be 2.4: I. The product which is of fine granularity, can be recycled as part of the feed after being agglomerated or after blending with suitable grade and size of the chrome ore.