Pressure acid leaching of zinc silicate ore.

The optimum conditions for the extraction of zinc from a zinc silicate ore by acid pressure leaching were determined in a laboratory study. The ore came from China's Yunnan province and contained willemite, hemimorphite, zincite, franklinite, as well as calcite, quartz and other minerals. The influences of particle size, sulphuric acid concentration, and leaching time, temperature and solid-liquid ratio were examined. The results showed that pressure acid leaching was effective for the recovery of zinc, with temperature and acidity being the most important variables. Raising the temperature from 80 degrees C to 160 degrees C reduced the dissolution of iron and silica but also reduced zinc extraction slightly. Increasing acid additions increased zinc recovery but also increased iron and silica dissolution. The particle size had little effect on both zinc recovery and iron and silica dissolution. 99% of the zinc could be extracted under the optimum conditions of 140 degrees C, 1.5 hr leach time, 0.46 mole/l acidity, liquid-solid ratio 6:1 and ore size less than 98 microns.
The optimum conditions for the extraction of zinc from a zinc silicate ore by acid pressure leaching were determined in a laboratory study. The ore came from China's Yunnan province and contained willemite, hemimorphite, zincite, franklinite, as well as calcite, quartz and other minerals. The influences of particle size, sulphuric acid concentration, and leaching time, temperature and solid-liquid ratio were examined. The results showed that pressure acid leaching was effective for the recovery of zinc, with temperature and acidity being the most important variables. Raising the temperature from 80 degrees C to 160 degrees C reduced the dissolution of iron and silica but also reduced zinc extraction slightly. Increasing acid additions increased zinc recovery but also increased iron and silica dissolution. The particle size had little effect on both zinc recovery and iron and silica dissolution. 99% of the zinc could be extracted under the optimum conditions of 140 degrees C, 1.5 hr leach time, 0.46 mole/l acidity, liquid-solid ratio 6:1 and ore size less than 98 microns.