Cominco, Ltd.

Robert F Redden

Thomas L Charlton

Horst E Hirsch

Roelof P Bult

Shou C Liang

Alan B Bollong

Cd and Te are purified by multiple-pass zone refining in the presence of a small amount of an added gettering substance chosen from Cd, Te and CdTe. In the purification of Cd, Te, or CdTe is added, the amount of Te or of Te in CdTe being less than the amount of Te in the Cd-rich eutectic composition between Cd and Te. In the purification of Te, Cd or CdTe is added, the amount of Cd or of Cd in CdTe being less than the amount of Cd in the Te-rich eutectic composition between Cd and Te. The Cd and Te so purified have an improved purity as witnessed by SSMS analyses, the increased ductility of the Cd and a much higher yield of the number of slices of CdHgTe produced with the refined Cd and Te meeting the specifications for carrier concentration and mobility.

Purification of Cd and Te by zone refining

A process is disclosed for the selective extraction of arsenic from oxidic materials containing compounds such as arsenic trioxide, arsenic pentoxide, antimony trioxide, antimony pentoxide, antimony tetroxide and mixtures thereof in which arsenic is effectively separated from antimony. Said oxidic materials are subjected to a leach with a lixiviant containing arsenic acid or hydrogen peroxide at a temperature in the range of 40.degree. C. to the boiling point of the reaction mixture, preferably in the range of 80.degree. to 100.degree. C., for 5 to 90 minutes. The leach solution containing arsenic oxides is separated from leach residue. The leach solution is either cooled to a temperature in the range of 5.degree. to 25.degree. C. to crystallize and subsequently recover arsenic trioxide or the solution is oxidized and evaporated and arsenic pentoxide is recovered. Arsenic acid lixiviant contains 5 to 500 g/l arsenic as arsenic pentoxide, preferably 25 to 200 g/l, and hydrogen peroxide lixiviant preferably contains a 10 to 60% hydrogen peroxide concentration.

Process for extracting arsenic from oxidic materials

A process is described for the recovery of gallium from scrap materials in which the gallium occurs as gallium compounds containing at least one element selected from the group consisting of aluminum, antimony, arsenic and phosphorus. The process comprises the steps of leaching said gallium compounds with an oxidizing agent selected from nitric acid and a combination of nitric acid and hydrogen peroxide to form a gallium-containing leach solution, forming a gallate solution from said gallium-containing solution, and recovering gallium from said gallate solution. The leach solution can be treated with a calcium compound chosen from the group consisting of lime and calcium hydroxide for precipitation of calcium arsenate and calcium phosphate. An alkaline material such as sodium hydroxide may then be added to said leach solution in an amount sufficient to raise the pH to a value of at least 11 to form gallate solution. Gallium metal preferably is recovered from said gallate solution by electrolysis. BACKGROUND OF THE INVENTION

Recovery of gallium from gallium compounds

Gallium and other values are recovered from phosphorus-furnace flue-dust by treating dust with sulfuric acid to form a solution and a residue. The residue may be treated for recovery of values. Zinc is precipitated from the solution as zinc ammonium sulfate hexahydrate and an alkaline material is added to precipitate a gallium concentrate and to form a gallium-free solution, which may be treated for recovery of sulfate and phosphate values. The gallium concentrate may be upgraded by mixing concentrate with lime to precipitate calcium phosphate and by subsequently adding sodium hydroxide to redissolve coprecipitated gallium and aluminum compounds. Residual precipitate is recycled and the solution is neutralized to precipitate an upgraded concentrate. Aluminum may be removed as calcium aluminate. Upgraded concentrate may be dissolved in alkaline solution and the solution electrolyzed for deposition and recovery of gallium.

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Fruitvale, Canada

Robert F Redden