Thermodynamic Investigations and Substantiation
of the Aluminothermic Fabrication Method of Calcium

V. K. Kulifeev*, A. N. Kropachev**, and V. P. Tarasov***

National University of Science and Technology “MISiS”, Leninskii pr. 4, Moscow, 119049 Russia

*e-mail: kulifeev@mail.ru

**e-mail: kan@misis.ru

***e-mail: vptar@misis.ru

Received July 1, 2014; in final form November 13, 2014; accepted for publication November 13, 2014

Abstract—To search for ways to solve the problem of decreasing the production prime cost of metallic cal-
cium, it is proposed to consider its aluminothermic production by the example of the CaO–Al system. The ther-
modynamic analysis implemented for this system showed that the aluminothermic reduction of calcium from
its oxide is technically performable under a pressure of 5–10 Pa and temperature of 1200–1500C. It is revealed
that the implementation of reduction under the residual pressure lower than 1 atm (101.3 Pa) considerably low-
ers the thermodynamic temperatures of the onset of the reaction. It is established that only three reactions, in
the course of which calcium aluminates 3CaO Al₂O₃, 5CaO 3Al₂O₃ (12CaO 7Al₂O₃), and CaO Al₂O₃ are
formed, can be used for the practical purposes. It is proposed, depending on the final state, to separate the pro-
cess into a “low-temperature” one (up to 1200C, the calcium yield is no higher than 64.3%) and a “high-tem-
perature” one (up to 1500C, up to 75% Ca). It is planned to further confirm these data experimentally.

Keywords: calcium, aluminothermic reduction, aluminates, thermodynamics, thermodynamic temperature of
reaction onset, vacuum

DOI: 10.3103/S1067821216010090

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