Study On A Novel Hydrometallurgical Technology Of Low Grade Oxide Zinc Ores

With quick consumption of zinc resource, low grade zinc oxide ores play an increasingly important role in production of zinc.The mineralogy of a certain low grade zinc oxide ore was studied. The result shows that the main zinc mineral is smithsonite, which is easy to be leached by H₂SO₄. Based on this, in H₂SO₄ system, effects of particle size of triturates, acidity, time and temperature on leaching rate of zinc and impurities were investigated. The optimized conditions to obtain a leaching rate of higher than 92% for zinc are : -0.074mm particle size of triturates accounting for 40⁵0 %; L/S being 3⁴/1;temperature within 60⁷0℃; reacting time of 1h. When two stage adverse current technology being employed, a leaching rate of 92⁹5% for zinc can be acheived, with Fe, Si and Al effectively restrained in the residue, so the contents of the impurities are very low in neutral leaching solution, which is favorable for further extracting system. An extracting process with three stage extracting, 2³ stage washing and two stage striping and using P204 as extracting agent being adopted, the raffinade containing 1²g/L Zn is directly obtained without saponification process of organic phase, and the striping liquor containing higher than 90g/L zinc andvery low content of impurities such as Cd²⁺ , Co²⁺ , Cu²⁺ , Fe³⁺ , F^- and Cl^- ion may directly be electrodeposited to produce high quality zinc metal without purification process.Effect of P204 on electrodeposition process of zinc was investigated. The result shows that if proper electrodeposition conditions are maitained, less than 5ppm content of P204 has little effect on the quality of zinc products, and the content of P204 in striping liquor can be reduced to less than lppm by activated carbon absorption.Preliminary technical and economical feasibility analysis shows that if the new process of leaching-extracting-electrodepositing is applied to treat low grade zinc oxide ores, the cost is 5000⁵500 yuan/tZn, which can produce a profit of 1000¹500 yuan/t zinc.