دانلود رایگان مقاله انگلیسی تحلیل نظری و مطالعه آزمایشی جداسازی فلز سیستم های دارای تنگستن - الزویر 2019

ABSTRACT

Based on the leaching solution of tungsten secondary resource, the metal separation properties of tungstencontaining systems such as the W-Mg-Si-H2O, the W-Al-H2O, the W-Fe-Mo-H2O and the W-Ca-V-H2O, were investigated by theoretical E-pH diagrams and experiments. The results demonstrated that the precipitation rates of Si and W were 99% and 2.4% respectively at pH = 9 in W-Mg-Si-H2O system; the precipitation rates of Al and W were 99.8% and 3.0% respectively at pH = 7 in W-Al-H2O system; the precipitation rates of W and Mo were 95% and 24% respectively at pH = 7 in W-Fe-Mo-H2O system; the precipitation rates of V and W were 91.2% and 4.3% respectively at pH = 13 with Ca:V = 3:1 in V-Ca-W-H2O system. The theoretical predictions were in good agreement with the experimental results. The metal separation for a tungsten-containing polymetallic solution of W, Mo, V, Si and Al, was designed and the parameters were optimized through the orthogonal experiments. The metals of (Si/Al), V, W and Mo were separated step by step with the precipitation rates exceeding 92%. This study provided a reference to metal comprehensive separation and recovery for the tungsten secondary resources.

4. Conclusions

(1) The E-pH diagrams of the tungsten-containing systems, such as the W-Mg-Si-H2O, the W-Al-H2O, the W-Fe-Mo-H2O and the W-Ca-VH2O, were plotted. The metal precipitation separation properties were studied through theoretical and experimental analysis. The results demonstrated that Si could precipitate with Mg to separate with ionic W at the pH 8–13.5 theoretically in the W-Mg-Si-H2O system, whereas the optimal experimental separation rate of Si was 99% with the W loss of 2.4% at pH 9. Al(OH)3 could precipitate out of the HW6O215− at 6 < pH < 8 theoretically in the W-Al-H2O system, whereas the optimal experimental separation rate of Al was 99.8% with the W loss of 3.0% at pH 7. W could be separated with Mo by the ferrous salt at pH 6–13 theoretically in the W-Fe-Mo-H2O system, whereas the optimal experimental separation rate of W was 95% with the Mo loss of 24% at pH = 7. V could be separated with W by calcium salts in strong alkaline environment theoretically in the W-Ca-V-H2O system, whereas the optimal experimental separation rate of V was 91.2% with the W loss of 4.3% at pH 13. The theoretical predictions and experimental results were basically in agreement. (2) The comprehensive separation process for tungsten-containing polymetallic solution of W, Mo, V, Si and Al was designed and the parameters were optimized through the orthogonal method. The optimal conditions for the separation of Si and Al by the magnesium sulfate were pH = 9, 50 min, 50 °C and Mg:Si = 1.4, with the desirable value of the precipitation rates of Si, Al, W, Mo and V approximately 92%, 99%, 4%, 5% and 5%. The optimal conditions for the separation of V by ferric sulfate were pH = 9, t = 50 min, T = 70 °C and Fe:V = 2, with the desirable value of the precipitation rates of V, W and Mo approximately 96%, 3% and 2%. The optimal conditions for the separation of W and Mo by ferrous sulfate were pH = 8, t = 30 min, T = 30 °C and Fe:W = 1.2, with the desirable value of the precipitation rates of W and Mo approximately 97% and 29%. The W total recovery rate was 90.68%. The comprehensive separation processes could selectively precipitate and separate metals, providing reference for the recovery of tungsten secondary resources.