Selective reduction separation and recovery of tellurium and bismuth from acidic leaching solution

Abstract

A simple and efficient method was proposed to selectively separate and recover tellurium and bismuth in an acidic leaching solution of tellurium−bismuth ore by Na2SO3 and Fe powder. Then, the selective reduction mechanism was investigated by SEM−EDS, XRD, XPS, ICP-OES, etc. 99.83% Te in leaching solution can be reduced by Na2SO3 with an excess coefficient of 16 at 80 °C for 10 min, and the grade of crude tellurium can reach 93.78%. Besides, the stirring action can accelerate the reduction of Te because the dissolution of Na2SO3 is promoted. Subsequently, 99.39% Bi in the reduced solution can be displaced by Fe powder with an excess coefficient of 7.5 at 60 °C for 40 min, and the grade of crude bismuth can reach 92.35%. Finally, cyclic leaching of tellurium−bismuth ore was adopted to enrich Te(IV) and Bi(III) concentrations and decrease the Fe(III) concentration in leaching solution, which can efficiently decrease the consumption of Na2SO3.