Abstract
Due to depletion of high-grade ores, high cost of mining and environmental issues, many mines have reverted to retreatment of slags. The recovery of Nickel from reverberatory furnace slag using sulfurization and flotation was studied. Critical parameters such as sulfurization temperature, sulfurization agent (Gypsum containing 86.87% CaSO4) dosage and time were investigated for the sulfurization process and effect of collector type and dosage, pH, particle size and flotation time for the flotation process. It was found that the slag contained 0.37% Cu and 0.19 % Ni as Copper oxide and Nickel oxide and other mineral phases such as fayalite, cuprospinnel and pentlandite. Optimum conditions for sulfurization were addition 20g of gypsum, 8g of Coke at a temperature of 950 under inert environment (argon) in a tube furnace for one hour. All of the Nickel oxide was sulfurized to Nickel sulfide and Millerite. 88.3 % Nickel was recovered after flotation under optimum conditions of 0.20g/t Potassium amyl xanthate (PAX), 5 drops of Dowfroth 200, 80% passing 75 microns at a pH of 7 in a micro flotation cell. The recovery of Nickel sulphide was very much dependent on collector dosage.