The mechanism of ultrasound oxidation effect on the pyrite for refractory gold ore pretreatment

Abstract

The effect of ultrasonic cavitation on the oxidation of the crystal pyrite in deionized water has been discussed. The effect of solution alkalinity, ultrasonic power and temperature on the surface morphology of pyrite and the chemical forms of sulfur and iron was discussed. The surface of pyrite is severely corroded under ultrasound. The sulfur in the pyrite is oxidized to S2O32- and SO42-. Most of the iron is in the form of Fe2+, few of it is in the form of Fe3+. With the increase of alkalinity, ultrasonic power and temperature, the surface corrosion of pyrite becomes more and more obvious. With the increase of the NaOH concentration, the Fe(II) concentration in solution decreases and the deposition of iron oxides on the pyrite surface prevents pyrite oxidation. With the increase of the ultrasonic power, the Fe(II) concentration in solution increase. The effect of the NaOH concentration on the SO42- and S2O32- concentration indicates pyrite oxidation is in mild alkalinity under ultrasound. The concentration of SO42- and S2O32- increases along with increase of the ultrasonic power and decreases tremendously with increase of the temperature. The pyrite oxidation is initiated by hydroxyl radical and promoted by Fe3+.