Study On Removal Of Organic Impurities From Zinc Lixivium

Fatty acid and amine are commonly used as collector of zinc oxide, which is detrimental to electrowinning of zinc by absorbing onto the surface of minerals into concentrates in flotation process firstly and then slipping into lixivium in leaching process. In order to eliminate the effect of organic impurities on the electrowinning of zinc, a series of exploratory experiments were conducted in this paper, of which the results and innovations are as follows:(1) According to the solution chemistry analysis of lixivium system, zinc was all existed in the form of Zn2+and the sodium oleate adding into the lixivium was mostly converted to zinc oleate when pH ranged from5.0to5.2. The residual content of (R-COO-)T which existed mainly in the forms of RCOO-and RCOOH (aq) in the lixivium was very low. However, the concentration of Zn2+and the pH value were decreased with increasing deposition of cathode zinc and the content of organic impurities increased by accumulating in electrowinning cell, which results in rapidly increased residual content of (R-COO-)T.(2) The effects of active carbon adsorption method, coagulate-sedimentation method and air-flotation method were studied on removing the organic impurities from the zinc lixivium. The results of these methods were compared as well. According to the tests, the active carbon adsorption method was considered to be the best way for purification.(3) The conditional experiments were carried out in the column flotation equipment of capacity of100milliliters. The results of removing sodium oleate from lixivium showed that the removal rate of sodium oleate and the retention rate of Zn2+can be up to91.58%and91.75%, respectively. The results of removing dodecylamine from lixivium showed that the removal rate of dodecylamine can up to98.13%. In other word, the result of removing impurities was good for the content of dodecylamine decreased from80mg/L to1.41mg/L(5) The influences of different factors on purification were compared by orthogonal analysis. The result of orthogonal analysis showed that the flotation time is more dominant than other factors, and the secondary factors are superficial velocity of air and height of froth layer in turn. The optimum levels are flotation time of6min, superficial velocity of air of0.60L/min and height of froth layer of1.0cm, respectively. Then the effects of flotation time (t), superficial velocity of air (v) and height of froth layer (cm) on removal rate of sodium oleate (R) were analyzed by multiple linear regressions. The regression equation was R=0.817+8.635t+65.328v-7.627h on the conditions of t∈[0,4],v∈[0,0.6],h∈[1,5.5]. At last, the mathematical model was determined by significance test of linear regressions.