RECOVERING METHOD FOR CADMIUM FROM WASTE CADMIUM PLATING BATH

摘要

PURPOSE:To recover high purity Cd from the titled bath in a high yield by treating the bath with a Cl type anion exchange resin column, washing the resin with formalin or the like to decompose the cyanocomplex of Cd adsorbed, and carrying out treatments with 2N hydrochloric acid, 2N NaOH contg. 2% NaCl, 1N nitric acid, etc. in order. CONSTITUTION:A waste Cd plating bath is treated with a Cl type anion exchange resin column to allow Zn and Cd to be adsorbed on the resin as the cyano-complex, and the resin is washed with formalin or chloral hydrate. The cyano-complex of Zn and Cd is decomposed to liberate Zn2+ and Cd2+, so in order to allow them to be adsorbed on the resin column again, 2N hydrochloric acid is fed into the column to convert the Zn2+ and Cd2+ into complex ion. Zn is then eluted with a 2N NaOH soln. contg. 2% NaCl, Cd with 1N nitric acid, and the eluate is evaporated to dryness. Thus, high purity Cd nitrate crystals are recovered in a high yield.