Oleg Ostrovski

Abstract:

The paper discusses (1) gaseous reduction of iron oxides and ores, (2) reduction of manganese, chromium and titanium oxides using methane-containing gas, (3) constraints in the reduction of manganese, chromium ores, ilmenite and quartz, and (4) the effect of the gas atmosphere in the carbothermal reduction of stable metal oxides. Reduction of metal oxides was studied using a fixed-bed reactor. Reduction of iron oxides and ores was also examined using high-temperature XRD.
Under standard conditions, methane is thermodynamically unstable above 550°C and decomposes to solid carbon and hydrogen. At appropriate CH₄/H₂ ratio and temperature, carbon activity in the methane-containing gas phase can be well above unity relative to graphite, which provides favorable thermodynamic conditions for reduction. To maintain these conditions, the rate of reduction/carburisation should be higher than the rate of solid carbon deposition. This condition is difficult to maintain in the reduction of stable oxides and ores. Carbothermal reduction of stable oxides in hydrogen is a promising avenue for processing of manganese ores and ilmenites.