Abstract:
At present, the solvent extraction method, which is the most widely used and highly mature purification separation method in industry, still faces problems such as low extraction rate, low separation coefficient between copper and impurities, long extraction equilibrium time, and difficulty in reverse extraction in the separation of calcium and other impurities in copper leaching solution. Therefore, this article proposed to apply a synergistic extraction system composed of tributyl phosphate (TBP, T) and (2-ethylhexyl) phosphate mono-2-ethylhexyl ester (P507, HP) to the extraction and separation of calcium and zinc in acidic solutions containing copper. The effect of factors such as extraction system composition, extraction time, extraction temperature, extraction ratio (
VO/
VA), and chloride ion concentration on the extraction rate of calcium and zinc was studied. The results indicated that the synergistic extraction system could selectively extract calcium and zinc simultaneously and significantly improve the extraction separation coefficient of copper and calcium and zinc compared with a single extraction agent. Under the conditions of a total concentration of 1.5 mol/L TBP-P507 in the synergistic extraction system, a TBP molar ratio of 0.4, extraction time of 5 min, extraction temperature of 30 ℃,
VO/
VA=2/1, and a total chloride ion concentration of 4 mol/L in the aqueous phase, the extraction rates of calcium and zinc were 94.69 and 85.20 while the copper extraction rate was only 2.56%. At this time, the separation coefficients of calcium copper and zinc copper were 680.47 and 219.46, respectively. The slope method research results indicated that the composition of the calcium zinc extraction complex might be M•2T
(o)•2P
(o) (where M represents Ca and Zn).