Abstract
Optimised flotation plants in the base metals industry in Botswana produced a 3.2%Ni, 0.18%Co and 4%Cu concentrate which was smelted in electric arc furnace before the flash furnace processing. Important amount of matte started to report into the slag due the changing feed mineralogy. Selected microorganisms were used to recover nickel from the matte-slag mixture. Bacillus spp. assisted dissolution of Ni, Cu and Co from matte-slag material showed a maximum recovery of 30%, 32% and 35% respectively.