Selective removal of antimony from refractory gold ores by ultrasound

Ultrasound is used to enhance the removal of antimony from the refractory gold ores in alkaline sodium sulfide leaching process. The effects of ultrasonic time, temperature, reagent concentration and ultrasonic power on antimony removal are discussed. The removal rate of antimony reached 94.50% when ultrasonic time was 60 min, sodium hydroxide concentration was 1 mol/L, sodium sulfide concentration was 2 mol/L, ultrasonic power was 1500 W and temperature was 55 degrees C. Under the conditions, the removal rate of antimony without ultrasound is only 58.37%. The results show that ultrasound can significantly improve the removal efficiency of antimony and reduce the leaching temperature and time of antimony. The leaching rate of gold increased from 13.35% to 40.56% after antimony removal. Moreover, the leaching rate of gold after antimony removal reached 68.90% under ultrasound. Therefore, ultrasound not only enhances the removal efficiency of antimony, but also improves the leaching rate of gold. The improvement of the leaching rate of antimony and gold is attributed to that the mineral particles are broken up and pyrite is decomposed by ultrasound.