Study On The Process Of Extracting Zinc From Low-grade Zinc Oxide Ores

With the development of industry, the demanding of metal zinc is more and more. Its annual growth is up to 2%. With the continuous zinc is being mined, the ore grade of zinc is more and more low. Therefore, metallurgy process of low grade zinc oxide mine is the focus of research in recent years.In this paper, according to the ore feature of low grade zinc ore in south of Gansu area, tests were carried out to study the leaching, extraction, electro deposition of ores. Leaching research studied the influence of temperature, the way of adding acid, solid-liquid ratio, pH value, particle size. The optimum technological conditions for leaching is as followed: leaching temperature 330 K, ratio of solid and liquid 1:3, concentration of acidity 150 g/L, the pH value of end between 5.2-5.5, zinc ore particle size 0.075-0.055 mm. Combined with the mineral characteristics, it proposes two stage leaching process, which is weak acid leaching and then strong acid leaching, and the leaching rate can reach 93%. In the extraction experiments, the factors of balance time, concentration extract agent, pH value are being studied. The optimum technological conditions are: extraction time 2-2.5min, concentration extract agent 25%, pH in between 2.8-3.2, and ratio of phase between 1.5-3. We also studied the effects of the concentration of zinc sulfate, ratio phase zinc and anti-extraction time, concentration sulfuric acid.The optimum processing condition are: concentration of zinc sulfate 30%, ratio phase 5, the content iron, calcium, cobalt in organic phase decreased significantly, and the washing effect is better. When anti-extraction time is in 4min, concentration of sulfuric acid is 130g/L, effect is better. The whole process test showed that, zinc of electrodepositing with national standards can be prepared, and the total recovery rate of zinc is 87.76%.