Preparation and Toxicity of Calcium tungstate

Calcium tungstate is a white powder, insoluble in water. It is often used for fluorescent paint, photographically-used optical screen tubes, medicine, X-ray photographs and fluorescent lamps, etc. Besides, Calcium tungstate also can be used in the production of tungsten products such as ammonium paratungstate, tungsten trioxide, ferrotungsten, alloy steel, hard alloy, tungsten, tungsten wire and tungsten alloy; used as raw material for tungsten series chemical products.

Preparation

Calcium tungstate is prepared by the following way: Calcium tungstate or calcium hydroxide is reacted with tungsten oxide or tungsten hydroxide in an alkali metal hydroxide or carbonate solution for production of Calcium tungstate. Mix the sodium tungstate with sodium sulfide, and dissolve it by water, and then add an aqueous solution of zinc chloride, get it filtered, and the filtrate is processed with pure calcium chloride to obtain calcium tungstate.

Toxicity

Exposure to tungsten compounds can cause irritation of the upper and deep respiratory tract and inflammation. Irritating to the skin. Operators should wear anti-poison respirators, dust-proof clothes, gloves, and glasses. Dust leakage shall be prevented at all stages of preparation and use of tungsten and its compounds.

Reference

J. S. Warner, Occupational exposure to airborne nickel in producing and using primary nickel products. In F. W. Sunderman, ed., Nickel in the Human Environment, IARC Sci. Publ. No. 53, IARC, Lyon, France, 1984, pp. 419–437.
C. Lid
en et al., Assessment of skin exposure to nickel, chromium and cobalt by acid wipe sampling and ICP-MS. Contact Dermatitis 54, 233–238 (2006).
C. Lid
en et al., Deposition of nickel, chromium and cobalt on the skin in some occupations: assessment by acid wipe sampling. Contact Dermatitis 58, 347–354 (2008).