Thermodynamics of reactions in reduction of niobium from its chlorides by magnesium

Thermodynamic calculations were made for all possible reactions in the case of thermal reduction of niobium by magnesium. In the interval of temperature 298-2000 deg K all the main reactions and reactions occurring prior to the reduction stage of lower niobium chlorides by magnesium and magnesium monochloride are possible, the step-wise reduction of chlorides being more probable thermodynamically. Changes in isobar-isothermal potential were calculated for secondary reactions of niobium chlorides with metallic niobium. The calculation showed that the investigated reactions can take place under conditions of a real process. The reaction of niobium pentachloride with metals used as part of structural material, and subsequent reduction by magnesium of the chlorides produced were shown to be thermodynamically possible. Disproportionation reactions of niobium tri- and tetrachlorides are not very likely to take place thermodynamically