“Tekhnokhim”, Zaporozhye, Ukraine:

D. V. Pruttskov, Research Adviser, phone: (+38061) 218-41-66
N. P. Krivoruchko, Technical Adviser

During the works, related to processing of technogenic silicon raw materials,there are presented the results of experimental-industrial researches, intended for the seeking of technical solutions on usage of fine sludge wastes of silicon carbide as raw material for silicon tetrachloride production. The production wastes of “black” silicon carbide were suggested to application in the form of pelletized mixture with silica sand using a combined binder, which consists of lignosulphonate and coal-tar pitch. Exothermic nature of silicon carbide chlorination provides the high reaction rate of pellets’ chlorination. However, if sand is absent, the chlorinator operating temperature will be disrupted. When silica sand is added to the pellet composition, a part of exothermic reaction heat is spent for its heating to such temperatures that the rate of SiO₂ chlorination becomes noticeable. It is empirically found that optimal mass ratio of silica sand and pelletized silicon carbide wastes equals (0.91.2):1 in terms of chlorination in a shaft chlorinator. Chlorination of pellets with such equivalence ratio ensured the stable operation of chlorinator and condensation system. Herewith, there were achieved the performance characteristics comparable to chlorination characteristics of pellets with silica sand and silicon mixture. Results of balance calculations showed that the degree of sand chlorination reached 35–37%. Comparison of technical and economic indices of silicon tetrachloride production method, using the silicon carbide wastes with indices of other well-known methods, makes it possible to conclude that this method is prospective. There is proposed a variant of silicon carbide and silicon tetrachloride co-production optimization, wherein the by-product partially carbidized charge (mixture of SiC and SiO₂) is sent directly to chlorination in the form of lump material.

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