A ROTATING-DISK STUDY OF GOLD DISSOLUTION BY BROMINE

Gold dissolution with bromine was studied using the rotating disk technique with Geobrom™ 3400 as a source of bromine. The parameters studied were speed of rotation, lixiviant concentration, pH, temperature, sulfuric acid and hydrochloric acid concentrations, and the concentrations of various cations (i.e., copper, iron, zinc, aluminum, manganese, potassium, and sodium) and anions (i.e., chloride, bromide, sulfate, nitrate, and iodide). According to the Lavich plot and activation energy, gold dissolution is controlled by a chemical reaction rate. Copper, iron, and manganese in their highest oxidation states, as well as aluminum, zinc, sodium, and potassium, have no effect on the rate of gold dissolution. The presence of manganous ion substantially decreases the gold dissolution rate. The kinetic performance of bromine was found to be dramatically better than the performance of cyanide and thiourea. © 1991 TMS.