| Most electrolytic zinc plants have to deal with dissolved magnesium in their process liquors, as zinc sulfide concentrates contain small amounts of magnesium. Applied magnesium bleed of methods are generally expensive and environmentally unfriendly. In this paper, a new approach is suggested and discussed in which magnesium fluoride is selectively precipitated from zinc sulfite solution. The main contents of this paper are as follows:1) With reference to the main components of the solution of the electrolytic zinc plants, the influence of the elements of zinc, magnesium, and manganese in the Zinc Hydrometallurgical process to calcium fluoride dissolution were studied. The experimental results indicate that the zinc ion, magnesium ion, manganese ion in the system had significant effects on the dissolution of calcium fluoride, among them magnesium ion among them had the most important influence. Under the optimum condition of such as the temperature of 90 ℃, zinc ion concentration of 120 g/L, and calcium fluoride solution saturated. The fluoride ion concentration was 160.42 mg/L; The solubility of calcium fluoride was 65.86×10-3g/100cm3Under the optimum condition of such as the temperature of 80℃, manganese ion concentration of 15 g/L, zinc ion concentration of 120 g/L, The solubility of calcium fluoride was 67.51×10-3g/100cm3By contrast, when the control temperature was 90 ℃, magnesium ions content was 20 g/L, zinc ion concentration was 120 g/L, calcium fluoride solution saturated, The solubility of calcium fluoride was 217.64×10-3g/100cm32) With zinc sulfate solution as matrix, optimum technological parameters of removing magnesium were studied. The experimental results indicate that the optimum conditions for the removal of magnesium from the solution are:zinc ion concentration of 130 g/L, the temperature of 90℃, the amount of fluorine theory ratio of 0.8,Under the optimal condition, the concentration of magnesium ion can be reduced to 1.04 g/L, and residual fluorine concentration was 410.33 mg/L. Good results in removing magnesium from the zinc hydrometallurgical process could be achieved. Compared to pure water system, the residual fluorine concentration increased; to join the seed can improve the depth of the removing of magnesium and reduce the residual fluorine ion concentration, and if the initial concentration of magnesium was higher, then magnesium removal effect would be better.3) Under the optimal process parameters which is the temperature of 90℃, Zn2+ concentration of 130 g/L, fluorine theory of volume ratio of 0.8, good results in removing magnesium from the zinc hydrometallurgical process could be achieved. The removal rate of magnesium was reached 97.21%, and the removal rate of fluorine was reached 82.79%. The F/Mg mole ratio in the slag was 1.98, filtering performance is good, and the purity of magnesium fluoride was 98%. Magnesium of 10.39 g/L can be remove to below 1 g/L, this fully meet the requirements of electrolyte solutions, but residual fluorine concentration was about 800 mg/L, do not conform to the requirements of the electrolyte, the next step of removing fluoride was needed.4) Under the condition of the optimal process parameters, the real solutions came from domestic zinc smelting enterprises was used to verify the effect of magnesium. The study found that Magnesium ion of 11.2 g/L and 11.55 g/L in real solutions can be remove to 0.98 g/L and 1.08 g/L, under the optimum condition of such as the temperature of 90 ℃, fluorine theory of volume ratio of 0.8. But residual fluorine concentration were respectively about 689.89 mg/L and 601.7 mg/L, do not conform to the requirements of the electrolyte. Fluoride precipitated method to remove magnesium is effective. The method which Sodium fluoride was used to remove magnesium is verified to be feasible. This can provide a relatively feasible reference model for dealing with zinc sulfate solution which contains much magnesium.
|
PDF Full Text Request