Evolution of Nil Waste Process for Utilization of some Mine Wastes

Abstract

The demand for quality concentrates, depletion of high grade reserves, increase in operating costs and environmental constraints poses challenging problems to all mineral industries. Closure of mines due to environmental problems force the industries to look for processing of mine wastes and old plant tails. It is in this context an effort is made to process some of mine wastes by nil waste technology yielding usable products for diverse industries thereby solving vexed problem of waste management and meeting the demand for raw materials. The clayey ferruginous bauxite reject sample from waste dumps of Kolli hills, Namakkaltaluk, Salem district, Tamil Nadu was subjected to characterization, process diagnostic amenability tests followed by process evolution studies comprising of of soaking, scrubbing, wet screening over 150 micron double deck screen oversize produced metallurgical grade assaying 46.50% Al2O3,1.49% reactive SiO2 and 21.70% Fe2O3 with 76.8% Al2O3 distribution at weight % yield of 67.0 and a dewatered screen under size cement / pottery grade concentrates assaying 28.63% Al2O3,32.28% Fe2O3 13.57% SiO2 and 20.41% LOI at wt% yield of 33.0. A wollastonite mine reject sample from Sirohi, Rajasthan was subjected to beneficiation process comprising of [1] Rougher calcite flotation at -150mesh,D8080 microns, 33%S, pH 7 using 2kg/t H2SO4 and 1kg/t of sodium oleate [2] two cleanings of rougher calcite float and recirculation of dewatered cleaner tails to rougher feed [3] Wet high intensity magnetic separation of Rougher tails at 19200 gauss. The above flotation –WHIMS process yielded a ceramic grade concentrate assaying 97% CaO.SiO2, 0.49% Fe2O3, 1.01% Al2O3 and 0.45% LOI at weight % yield of 75.0. The cleaner calcite float assaying 45.6% CaO, 7.20% Fe2O3, 4.21% Al2O3, 5.89% SiO2 and 36.22% LOI may be used as by-product as it meets cement grade.