GB466534A - Improvements in or relating to a process for the extraction of cadium - Google Patents

Abstract

466,534. Precipitating and refining cadmium. BERZELIUS METALLHUTTEN GES. April 23, 1936, No. 11594. Convention date, April 25, 1935. [Class 82 (i)] Cadmium sponge is treated to remove part of the water contained therein and is then melted down in a caustic alkali melt to remove the excess of precipitating metal and impurities such as sulphur, arsenic, antimony, iron, copper, and ceramics. The melting may be effected in an iron crucible 2 heated in a furnace 10, the sponge, in small pieces, being contained in a perforated iron container 1 immersed periodically in the alkali melt 3 by operation of a hand wheel 12. Lead, if present in the raw material, is removed in the manufacture of the sponge by dissolving the raw material in dilute sulphuric acid, clarifying the solution, and precipitating the cadmium by means of refined zinc ; if free of lead, the precipitation may be effected without complete solution of the raw material. Precipitation may be effected in lead tanks 9 lined at 5 with masonry and provided with an agitator 6. Water may be removed from the sponge by pressing or centrifuging. Instead of zinc, aluminium, magnesium or iron may be used as the precipitating metal. The solidified regulus 4 is washed, dried and remelted in paraffin and the alkali melt 3 may be dissolved in water to extract any pellets of cadmium remaining therein and the zinc sulphate, tin, &c. contained therein may be recovered. Any cadmium pellets extracted may be united to form a regulus by further treatment with alkali.