Selective Dissolution and Mechanism of Arsenopyrite by the Oxidizing Agent in Alkaline Leaching System

Arsenopyrite is a common gold-bearing mineral, and the presence of arsenic leads to difficulties in gold recovery. In this paper, the effects of leaching time, NaOH concentration, temperature and potassium permanganate concentration on the arsenic leaching rate in the process of arsenopyrite arsenic removal by atmospheric pressure alkaline leaching were investigated, and the leaching mechanism of potassium permanganate was elucidated by combining electrochemical and kinetic analysis. The results showed that the highest arsenic leaching rate of 63.72% was achieved when 0.25 mol/L potassium permanganate was used as the oxidant and the NaOH concentration was 3.5 mol/L. Electrochemical and kinetic analyses showed that the decisive step controlling the rate of arsenopyrite atmospheric pressure alkali leaching reaction was the chemical reaction step. The apparent activation energy of the reaction is 40.19 kJ/mol. Oxidizing agents such as potassium permanganate promote the oxidative dissolution of iron at the beginning of the alkaline leaching of arsenopyrite.