Tellurium Production
Tellurium Production
Tellurium is extracted by sulphide ores processing from semi-products of copper, lead-zinc manufacture, as well as from some gold ores. Copper electrolysis sludge which contains from 0.5 to 2% Tellurium, as well as silver, gold, selenium and copper may me used as main feed stock in Tellurium production.
For this purpose sludge first should be freed from copper and selenium; the rest, which contains noble metals with Tellurium, lead, tin and other components is fused for obtaining a gold-silver alloy. Tellurium in form of Na2TeO3 passes into soda-tellurium slag in which concentration of Tellurium reaches 20-35%. Slag is crushed, milled and leached by water. Te is extracted from the solution on cathode. The extracted tellurium concentrate is treated by alkaline in the presence of aluminum powder, converting tellurium into dissolved tellurides. The solution is separated from insoluble heavy metals impurities concentrates and in blown by air. 99%-pure tellurium precipitates in elementary state. High-purity tellurium is obtained after recurrent recovery process. Most pure tellurium in extracted by combination of chemical refinement, distillation and zone melting.