| With the quick development of China’s economy, the demand for zinc metal is huge, and the problem of zinc shortage is becoming serious while the high-grade zinc sulfide resource is depleting. However, in this grim situation, a lot of low grade of zinc oxide resources are not reasonably exploited and utilized due to lack of effective processing technology. Thus, it is very important to develop new technology and process to utilize the low-grade mixed zinc mine effectively as soon as possible. On one hand, it can become a new growth point of national economic development, on the other hand, it will facilitate the economic security of China by reducing the dependence on importation of zinc concentrate and refined zinc. Therefore, it is significant to the enterprises and country to utilize comprehensively of the low-grade refractory mixed zinc mine, especially to Yunnan province which has a large number of zinc reserves and is located on the border of the motherland.In this work, a mixed zinc ore was studied which was gathered from Xinjiang Kashga. Process mineralogy investigate of the ore indicated that the ore contains1.81%of zinc, oxygenation rate is37%. The main zinc minerals of the ore are sphalerite, smithsonite and willemite, while the main gangue minerals are silicon minerals. The dissemination sizes of zinc minerals are uneven, and it may easily be mudding when grinding because the ore is fragile. Therefore, this ore is a typical low grade, high silicon content mixed zinc ore.In this work,"ammonia dissolution", a type of chemical processing, was used to recover the zinc oxide ore, The leaching system, leaching factors and process were studied by using agitation leaching in the laboratory. It is found that the ammonia-ammonium sulfate dissolution system is the best to deal with this mine. The optimal experimental conditions are that the concentration of NH3is4mol/L, the concentration of (NH4)2SO4is2mol/L, the liquid-solid ratio is4:1, mineral fineness is-0.074mm fraction taken up80%, the leaching time is2h, the leaching temperature is40℃, the agitator speed is300rpm and the process is one-section leaching. Under the optimal conditions which are listed front, the leach ratio of zinc oxide could achieve91.76%. Chemical thermodynamics and kinetics of ammonia dissolution system were discussed, we found that the pH value of the optimal leaching system was8.72, the zinc was mainly in the form of Zn(NH3)42+, The zinc ammonia-ammonium dissolution was first order chemical reaction which was controlled by diffusion process. The rationality of the optimum dissolution system and leaching conditions were proved by chemical thermodynamics and kinetics discussed.Zinc leaching residue phase analysis showed that calamine and zinc silicon can be dissolved by ammonia-ammonium sulfate leaching system while the zinc sulfide ore can’t be.The results of the flotation of the raw ore and the leaching residue showed that the dissolution treatment by the ammonia-ammonium sulfate leaching system can obviously improve the floatability of the zinc sulfide ore. So zinc oxide ammonia-ammonium dissolving activation flotation hypothesis was suggested. Through the test, grinding fineness80%-74μm, copper sulfate dosage200+50g/t, butyl xanthate dosage150+50g/t,2#oil consumption40+20g/t were considered as the optimum flotation conditions, and on those conditions, the zinc concentrate grade was40.56%, concentrate recovery was36.38%.Znic recovery of the Metallurgy-Flotation process was70.35%. |
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