Vacuum thermal decomposition behavior of Ag2Te

Abstract

Silver and tellurium are crucial valuable metallic elements in anode slimes. During pyrometallurgical processing, tellurium exists in the alloy as the stable compound Ag2Te. The current process of separating tellurium from silver-tellurium compounds in crude silver by oxidizing tellurium into slag leads to undesirable loss of silver, low recovery rates of tellurium, and considerable slag. An environmentally friendly and efficient vacuum thermal decomposition process of Ag2Te was proposed, and the effects of temperature, pressure, and holding time on the decomposition of Ag2Te were investigated. The Experimental temperature was thermodynamically calculated to be in the range of 1473–1673 K and pressure in the range of 1–100 Pa. As the temperature increases, especially above 1573 K, the silver volatiles increase significantly, and silver and tellurium vapors react strongly to form stable silver-tellurium compounds. Investigating the volatilization and condensation mechanisms of silver and tellurium highlights the importance of inhibiting silver volatilization to achieve efficient separation of silver and tellurium. Volatiles containing 98.85% tellurium mainly as tellurium monomer, and a remained melt consisting of 95.56% silver primarily as silver monomer were produced at 1523 K, 50 Pa, and an 8-h holding time.