GRAPHITE REDUCTION OF MOLTEN NICKEL MATTE/OXYSULFIDE/SLAG Part II: Nickel Matte and Slag+Matte Reduction

The mechanism and rate of carbon reduction of each phase formed in the flash flame, specifically sulfide (matte) and oxysulfide, were investigated. This study aimed to measure the rate of solid graphite reduction of matte, oxysulfide, slag, and a matte+slag mixture at different temperatures. Key components included understanding and explaining the reduction mechanism of these materials by comparing respective reaction rates, product gas compositions, CO/CO2 ratios, reduced material assays, activation energies, and other relevant parameters. Direct visual inspection of the test crucibles also provided additional insights. Additionally, it was observed that improved metallurgy of Inco’s nickel flash furnace, particularly through increasing recovery of valuable metals, could result from modifying operating conditions to achieve a sulfur-deficient matte. Previous methods in commercial nickel smelting, which primarily relied on electric furnace operations, highlighted the necessity of further studies regarding the addition of coke or coal to flash furnaces, as existing knowledge is limited. This investigation represents a crucial step toward evaluating an operational mode for the Inco flash furnace by establishing a reducing barrier on the molten bath's surface.