Thermodynamic analysis of conditions for iron and titanium separation in ilmenite concentrate by selective reduction of elements

The thermodynamic modeling method was used to determine the temperature of beginning of reduction of iron, vanadium, silicon, and titanium in ilmenite concentrate by carbon or hydrogen at different amounts of reducing agent in the system. The amount of excess carbon relative to the stoichiometry of the iron reduction reaction does not affect the temperature of reduction beginning, but determines their reduction degree and the amount of carbides formed. The amount of hydrogen in the system significantly affects the temperature of reduction beginning: with an increase in water amount, this temperature of each element decreases, but to a different extent. The wider temperature range of beginning of reduction by hydrogen and the quantitatively unequal effect of temperature create more opportunities for controlling the solid-phase selective reduction by hydrogen in comparison with carbon. In contrast to the carbothermic process, the solid-phase reduction of titanium by hydrogen is negligible at relatively low temperatures, at which titanium is reduced by carbon and forms carbides. The low solubility of hydrogen in solid iron excludes its influence on the behavior of elements at the stage of separation melting of solid-phase reduction products. This makes it possible to carry out reduction in hydrogen flow by changing the temperature and amount of hydrogen in the reducing gas mixture, and to control the processes of selective solid-phase reduction of elements. The use of hydrogen at the stage of solid-phase reduction makes it possible to selectively reduce iron with the storage of titanium oxides in the oxide phase in form of TiO 2 , and after separation of the reduction products by melting, to obtain the products in demand (carbon-free iron and TiO 2 concentrate).