Impacts of ultrasound on leaching recovery of zinc from low grade zinc oxide ore

On the basis of an experiment on ultrasonic enhanced ammonia leaching of low grade zinc oxide ores, the effects of the total ammonia concentration, the ratio between the NH3 concentration (CNH3) and that of ammonium sulfate (NH4)2SO4 (C(NH4)2SO4), and the ultrasound power on zinc leaching rate were studied. The results showed that the leaching efficiency of zinc observably increased with the increase of the total ammonia concentration, and that the ratios between CNH3 and C(NH4)2SO4 can remarkably affect the zinc extraction from the low grade zinc oxide ores. When the ratio between CNH3 and C(NH4)2SO4 is 2 to 1, the leaching rates of zinc are observably improved. The ultrasound can improve the leaching efficiency of zinc, and its effect was especially pronounced when the NH3 concentrations were low. The higher ultrasound power cannot sensibly improve the leaching rate of zinc, but it can improve the leaching speed and shorten the leaching time. Under the optimized conditions - total ammonia concentration of 8 mol/l, ratio between CNH3 and C(NH4)2SO4 of 2 to 1, and ultrasound power of 600 W – 83.33% of zinc is recovered.