The processes of calciothermic reduction of metals from iron (FeTa_(2)O_(6)) and manganese (MnTa_(2)O_(6)) tantalates as well as tantalum oxide (Ta_(2)O_(5)) were studied in this work. According to the results of thermodynamic analysis performed in the temperature range of 373–2773 K, the interaction of FeTa_(2)O_(6)and MnTa_(2)O_(6)with calcium proceeds with complete reduction of metals. The calculation and comparison of the log K equilibrium constants for the reactions of alumino- and calciothermic reduction of iron and manganese tantalates showed the thermodynamic advantage of using metallic calcium as a reducing agent. Experimental investigations of calciothermal reduction on samples of synthesized oxides were carried out by the method of combined thermogravimetry and differential thermal analysis in the mode of nonisothermal heating to 1473?K in an argon flow. X-ray powder diffraction was used to determine the phase composition of the initial samples and interaction products. It was shown that the calciothermic reduction of metals from the synthesized manganese tantalate proceeds actively at temperatures above 1196 K, while iron tantalate and tantalum oxide with the appearance of molten calcium. Tantalum and its solid solutions with iron or manganese, corresponding to the structural type Ta_(7)Fe_(6), were included in the main metal components of the products of the interaction of FeTa_(2)O_(6)and MnTa_(2)O_(6)with calcium.
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