Studies On The Optimization Of Technics For Leaching Tellurium From The Refractory Copper Slag

This work is the study of improving the leaching rate of tellurium from refractory copperslag,which formed in sulfation-roasting method for the recovery of tellurium, According to thecomposition of the raw meterial，a leaching method of taking redox means as the leaehing agentwas selected.This study discussed using sulfuric acid, potassium hydroxide and sodium hydroxide toleaching tellurium separately,studying the impect of improving the tellurium leaching rate bymeans of adding various redox.The preliminary indicated that the leaching rate of tellurium is between30%and60%whenleaching is conducted in sulfuric acid, potassium hydroxide, sodium hydroxide alone. Oxidantsplays a catalytic role for leaching tellurium in sulfuric acid,but the reducing agents in opposite,theleaching rate of tellurium can increase to64%when adding sodium chlorate; Adding hydrazinehydrate, sodium sulfide, sodium sulfite, the tellurium leaching rate increased significantly whenpotassium hydroxide as the leaching agent, and sodium sulfite is the most,all the leaching factorshave been investigated,under the opuimum condition the leaching rate with sodium sulfite andpotassium hydroxide is77.59%,but also can’t achieve the purpose of the research;When addingchlorite, sodium sulfite the leaching rate of tellurium improved significantly with the sodiumhydroxide,the study selected the mixture of sodium sulfite and tellurium to leach tellurium finally.The effects of leaehing temperature,leaehing time and the liquid to solid ration on the leachingefficiencie of tellurium have been investigated. In the leaehing by mixture of sodium sulfite andtellurium，the effect of order between them also investigated.From what abrove discussed,theoptimum conditionis liquid to solid ration of4:1, the amount of sodium sulfite is20g, sodiumhydroxide concentration is1.2mol·L-1, leaching copper slag for one hour under the sodium sulfiteand control the temperature always65oC, then adding sodium hydroxide and put the pulptemperature rose to85oC for another hour,under this condition,the leaching rate reach89.33%,andthe silver content less than5mg·L-1,gold content under3mg·L-1in tellurium solution.the purposesof improving leaching rate of tellurium and controling the silver and gold content in the elluriumsolution are all reached.