Use of non-conventional slags for cement making

The iron and steel industries around the world are responsible for the generation of large amounts of waste, mainly because they process huge quantities of raw materials. Disposal of these wastes is causing serious threat to the environment. Minimization of wastes through recycling has gained special significance in the present scenario, which also solves, to a certain extent, the disposal problem associated with these wastes. Presently at Tata Steel a major thrust has been given to becoming a Zero Waste Industry. The utilization of solid wastes there has improved from 44% in 1995-96 to 67% in 1998-99. The waste, generated in the form ofblast furnace slag, LD slag, flue dust, mill-scale etc are recycled in the different processes. Apart from these, Fe-Cr slag (54 000 t per annum) is generated at Tata Steels'Ferro Chrome Plant at Bamnipal. Of various slags produced, the blast furnace slag forms a major part which is utilized after granulation for making slag cement. This paper describes the studies carried out for the recovery of Fe-Cr from granulated slag, utilizing remaining slag in blended cement, and also the use of steel-making slag in clinkerization as a replacement for limestone.