The cobalt-nickel and magnesium were separated from the sulfuric acid solution by activated magnesium oxide precipitation, and then the cobalt and nickel were separated by the P507-N235 unsaponified extraction system to study the influencing factors and process conditions of cobalt-nickel and magnesium precipitation separation and cobalt-nickel extraction separation, as well as the mechanism of cobalt-nickel precipitation, magnesium oxide recovery and aqueous phase loss during extraction, and to compare the P507-N235 system and the sodium-saponified P507 system for the extraction separation of cobalt Ni effect.
The main research contents and results of the whole paper are as follows:
(1) The sodium saponified P507 system separates cobalt and nickel, compared with O/A=2:1, the phase separation effect is good, but the cobalt and nickel are almost completely extracted, and it is difficult to achieve the separation of cobalt and nickel; O/A decreases from 2:1 to 1:30, the extraction rate of both cobalt and nickel decreases, but the nickel extraction rate decreases more, so β(Co/Ni) gradually increases; under the condition of O/A≤1:1, the extraction phase separation time is longer, both are greater than 1h. Compared with the O/A of 1:30, the β(Co/Ni) was 119.6, and the initial separation of cobalt and nickel could be achieved; the loaded organic phase was washed with 0.05 mol/L sulfuric acid at O/A of 3:1 in three stages, and the co-extracted nickel could be washed off completely; the washed loaded organic phase was washed with 0.25 mol/L sulfuric acid at O/A of 2:1 in two stages, and the cobalt could be reverse extracted. The cobalt could be completely reverse extracted. The cobalt-nickel extraction rate decreased with the increase of Mg2+ concentration in the feed solution. The extraction rate of cobalt, nickel and magnesium decreased with the decrease of O/A, but the decrease of nickel and magnesium extraction rate was larger, so the β(Co/Ni) and β(Co/Mg) increased gradually in the sodium saponification P507 system.
(2) P507-N235 system extracted and separated cobalt and nickel, the cobalt extraction rate increased with the increase of pH of the feed solution but the increase was gradually smaller, while the increase of nickel was smaller. The equilibrium pH of the aqueous phase increased with the increase of pH of the feed solution and then remained almost unchanged, but...
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