ROLE OF SEGREGATION PROCESS ATMOSPHERE IN FORMATION AND COMPOSITION OF FERRONICKEL GRAINS

Experimental conditions have been established for the preparation of f erronickel grains from oxide ores by the segregation process. It is sh own that the nickel content of the metallic grains and the chemical co mposition of the reaction atmosphere are closely related. The view put forward by some Japanese investigators that it is not possible to pro duce ferronickel grains with a nickel content that exceeds 60 wt% is q uestioned. The interpretation of experimental data that were acquired during the segregation of three types of nickel ores (low- and high-gr ade silicate and low-grade magnesite) is based on the equilibrium diag ram for metallic and oxide species of nickel and iron plotted for vari ous CO2/CO ratios and temperatures. A high correlation is demonstrated between the amount of reduced iron in the ferronickel grains and the concentration of carbon monoxide and dioxide in the reaction atmospher e. Segregation process parameters that favour the formation of metalli c grains containing more than 90 wt% nickel have been determined.