Abstract
In a Southern African base metal integrated mine, about 120 tonnes per hour of concentrate feed a flash furnace. The slag produced therefrom fed into two 2.5 MW electric furnaces in series, is cleaned from 0.6%Ni to around 0.24%Ni using lump coal. Although most of the Ni in the slag occurs as sulfides, the slag is oxidized and contains a higher amount of magnetite. This affects the settling of en-trained metal particles in the matte. Recovering Ni from the slag would require an increase in the electric power of the furnace, increase in the residence time or the use of appropriate reducing agents, dissolution in appropriate lixiviant or froth flotation. Sample material from the flash furnace was crushed a! nd wet ground for varying times at a slurry density of 65% solids W/W. Different flotation reagents suites were used. Despite a low (2.60% S) sulfur content found in the slag, a flotation recovery of above 80% with 85% Ni was achieved.