Investigation of leaching of zinc from oxide waste using citric acid

The increasing demand for zinc has made it more important to be recovered from secondary sources. Hydrometallurgical processes have been more considered due to numerous pyrometallurgy problems. The most important advantages such as low cost, less pollution, less time and higher purity of product have made the researchers attracted. Accordingly, zinc recovery has been investigated from an induction furnace waste containing more than 30% zinc oxide in this study. Includes crushing and analyzing of waste particles, leaching in citric acid as an organic acid and investigating of the effective parameters were used in the process. Acid concentration, leaching time, temperature and amount of waste particles were the parameters that were studied. According to the results, the optimal conditions were as acid concentration: 1.5M, time: 60min, temperature 60 °C, and waste particles: 1.5g. Under these conditions, a recovery rate of 82% was obtained for zinc metal. The kinetic and thermodynamic zinc acidic leaching were also studied. The results showed that the surface chemical reaction acts as controller.