“Vac ETO” LLC, Moscow, Russia:

V. V. Falin, Researcher, e-mail: raven0607@rambler.ru
O. B. Minkov, Executive Officer
G. V. Molev, Head of Department
A. V. Sukharev, Deputy Chief Executive Officer

National University of Science and Technology “MISiS”, Moscow, Russia:
V. P. Tarasov, Head of the Chair of Non-Ferrous Metals and Gold

There was researched the metallothermal reduction of calcium oxide by reductors of Al – Si – Fe system with constant parameters (temperature is 1350 ^oC; holding during 3 hours; residual pressure is 1 Pa). Aluminium content in composition of obtained calcium distillate with application of Al – Si, Al – Si – Fe reductors is decreased by an order (in comparison with aluminothermic reduction) and corresponds to aluminium content in calcium with reduction by ferrosilicon FS 75. There is experimentally shown that calcium yield depends complexly on the reductor composition. There is supposed that explanation of such phenomena is connected not only with individual properties of reductor itself, but also with difference between melt-reductor liquidus temperature and operating temperature, or between the temperature dependence of surface tension of melt. Such supposition is in satisfactory agreement with earlier obtained results. Accounting of surface tense of meltreductor makes it possible to solve the existing disagreement between values of observed reduction activation energy and calcium evaporation heat or calcium diffusion activation energy to the surface of charge briquettes. At the same time, reduction activation energy corresponds to the calcium evaporation heat. Comparative experiments of reduction of calcium oxide (aluminothermal and Al – Fe-reduction) with content of carbonate and calcium hydroxide (2 and 1% respectively) were carried out with the temperature of 1300 ^oC, and 3 hours holding. These experiments have shown that presence of iron in the content of reductor increases the yield with simultaneous decreasing of costs for preparation of charge. Possibility of estimation of the required temperature of process for obtaining of the given yield (according to results of experiment for one temperature (higher than liquidus temperature)) appears for the chosen content of reductor.

1. Obzor rynka kaltsiya metallicheskogo v Rossii i mire (Review of metallic calcium market in Russia and in the world). Available at: http://www.infomine.ru. (August 2011). 102 p.
2. Budanov R. E., Minkov O. B., Molev G. N. et al. Tsvetnye Metally — Non-ferrous metals. 2009. No. 1. pp. 54–58.
3. Paket programm FACT-Win/F*A*C*T i ChemSage/SOLGASMIX (Program package FACT-Win/F*A*C*T and ChemSage/SOLGASMIX). Available at: http://www.crct.polymtl.ca/fact/documentation/.
4. Vatulin I. I., Minkov O. B., Sukharev A. V. et al. Materialovedenie – Materials Science. 2009. No. 3. pp. 46–50.
5. Kovalenko V. F. Teplofizicheskie protsessy i elektro vakuumnye pribory (Thermal physical processes and electronic-vacuum devices). Moscow : Sovetskoe radio, 1975. 216 p.
6. Kulifeev V. K., Kropachev A. N., Miklushevskiy V. V., Vatulin I. I. Tsvetnye Metally — Non-ferrous metals. 2004. No. 10. pp. 58–61.
7. Fiziko-khimicheskie svoystva elementov : spravochnik (Physical-chemical properties of elements : reference book). Under the editorship of G. V. Samsonov. Kiev : Naukova dumka, 1965. 808 p.
8. Schwandt C. S., Cygan R. T., Westrich H. R. Ca self-diffusion in grossular garnet. American Mineralogist. 1996. Vol. 81. pp. 448–451.
9. Glagolev K. V., Morozov A. N. Fizicheskaya termodinamika (Physical thermodynamics). Moscow : N. E. Bauman Moscow State Technical University, 2007. 272 p.
10. Doronin N. A. Kaltsiy (Calcium). Moscow : Gosatomizdat, 1962. 190 p.