A process for the oxidative dissolution of selenium and tellurium of Anode slimes

摘要

Anodic slimes obtained from electrowinning copper often contain selenium, tellurium and gold and/or platinum group metals. Pyrometallurgical techniques require close control to avoid emission of highly toxic selenium, and the known hydrometallurgical technique suffers from the disadvantage of oxidising at least a substantial proportion of the selenium/tellurium to the IV oxidation state from which they have to be reduced before separation can occur. The present invention provides a convenient hydrometallurgical process for oxidising selenium and tellurium direct to the +IV oxidation state using dilute, mildly acidic aqueous hydrogen peroxide, preferably in an amount of from 150% to 300% of the stoichiometric amount, and at a concentration of 5 to 15% w/w obtained by diluting stabilised concentrated hydrogen peroxide. The selenium and tellurium can subsequently be separated using appropriate pH control and sulphur dioxide reduction.