Gipronickel Institute Ltd

T. N. Greyver, Chief Researcher
M. A. Lastochkina, Senior Researcher, e-mail: MALas@nikel.spb.su
G. V. Glazunova, 1st Category Engineer
T. V. Vergizova, Senior Researcher, Laboratory of Hydrometallurgy

Methods of elemental selenium direct precipitation from selenium (VI)-containing solutions by hydrazine and by cementation using electronegative metals in the presence of titanium salts as catalysts are discussed. Both above-mentioned reagents make it possible to reduce selenium (VI) at temperature below 100 ^oС and standard pressure. Use of the reagents is not accompanied by chlorine and other toxic gases emission, which takes place in the process of selenium (VI) reduction using chlorine ion. Use of hydrazine as a reducing agent makes it possible to produce industrial selenium corresponding to GOST requirements for commercial selenium of lower grades without any additional stages. Selenium produced by catalytic precipitation contains >98% Se, but due to the impurities present it needs additional treatment. In both cases, cleaning by well-known methods allows producing selenium of higher grades. Selenium (VI) catalytic precipitation from rich selenium solutions in the presence of titanium salts gives way to the method of precipitation by hydrazine. However, it could be efficient for profound selenium removal from solutions.

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