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A Process for the Treatment of Flue Dusts and Other Wastes Containing Indium.
Proc 2nd Int'l Symp-recycling of Metals & Eng Mat Miner Met & Mater Soc 1990 :515-28
The treatment of indium-containing feedstocks, such as flue dusts, is uneconomic if the material has a low concentration of indium and at the same time contains a significant amount of lead. Therefore, it is desirable to extract the lead prior to indium recovery. Such a process has been developed based on the selective reduction of lead sulfate, lead oxide, and lead sulfide, contained in flue dusts, with metallic sodium. The first stage of the process entails the use of a sodium-doped lead bullion at temperatures ranging from 675 to 800 deg. C. Soda ash is blended with the feedstock and added to the sodium-doped lead bullion. Upon reaction, a liquid dross is formed. The liquid dross is removed, cooled, and crushed. The sodium is extracted from the powdered dross by water leaching. The resultant residue can then be processed by conventional methods for the recovery of indium. The lead reduced from the feedstock is recovered in the molten bullion. Indium recovery to the filter cake is typically 90 to 95 pct, while retention of lead in the filter cake is usually 5 to 15 pct. The concentration of indium in the filter cake is approximately twice that of the original feedstock. The sodium consumption ranges from 0.1 to 0.2 Lb sodium per pound of feedstock.
Proc 2nd Int'l Symp-recycling of Metals & Eng Mat.; Miner. Met. & Mater. Soc., 1990, PP. 515-28
Colorado School of Mines
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