| Aiming at the bio-leaching solution which is complex, low content of valuale metal ions and high content of impurity elements, the study which is one part of the mechanism of high efficient separation of valuable metal ions in the microbiological leaching solutions under different extraction systems was mainly about the influence of impurity ions accumulation on the extraction process under different extraction systems, finding out the influence law of different impurity ions on the separation of nickel and cobalt and providing the basis for shortening the purification process of the leaching solutions. On the basis of the understanding of influence law of different impurity ions on the separation of nickel and cobalt, the suitable extraction systems were explored to be used for impurity removal in the nickel-cobalt solution containing large amounts of impurities, in order to reduce the impact of impurity ions on the separation of nickel and cobalt and achieve the purpose of the separation and recovery of nickel and cobalt.Based on the bio-leaching solution in Baishan of Jilin province,the paper investigated the impact of the major impurity ions on the separaion of nickel and cobalt in the single extractor systems (P507, Cyanex272) and synergistic system (P507-Cyanex272) respectively. The results show that: Cyanex272system was affected most seriously by the impurity ions and a small increase of impurity ions would make a dramatic decline on the separation factor of nickel and cobalt. Fe3+influenced the separation of nickel and cobalt most seriously. When the synergistic extraction system was used in the process of the extraction separation of nickel and cobalt, the impurity ions in the feed liquid should be controlled within a certain range and the highest levels of Mg2+, Ca2+, Fe2+, Fe3+were:90mg/L,21mg/L,52mg/L,8.8mg/L.The paper explored the influence law of various process parameters on the impurity removal of the bio-leaching solution containing high levels of imputities and low content of nickel and cobalt, and the parameters in the process of scrubbing and stripping.Under the conditions of room temperature (25℃), the oscillation frequency of200rpm for4min, aiming at the simulated solution, the optimum extraction conditions to achieve the separation of valuable metals and impurities were:initial pH of2.5, O/A ratio of1/3, saponification rate of60%by using Versatic10. Under these conditions the extraction rates of nickel and cobalt were both above96%, and the co-extraction rates of cacium and magnesium were both below5%. The cobalt and nickel loaded Versatic10was subjected to scrubbing with deioned water (pH=6.50) by O/A ratio of1/1twice. It was found that calcium and magnesium, co-extracted with cobalt and nickel in the organic phase, could be effectively scrubbed out from the loaded organic with final co-extraction not exceeding0.5%. Based on the statistical analysis of the results, the optimum conditions determined for the simultaneous cobalt and nickel stripping from the loaded Versatic10in one stage, were:H2SO4concentration=2mol/L and O/A=1/1. At these conditions the stripping rates of nickel and cobalt were both above99%.Relative to VersaticlO system, Versaticl0-Cyanex301system could significantly lower pH value of the extraction separation of nickel, cobalt and calcium, magnesium from6.8to3.5. And it provides the possibility that the raffinate directly returns to the ore heap. Under the same conditions, in order to achieve the stripping of the loaded organic, the best volume ratio of VersaticlO and Cyanex301in the Versatic10-Cyanex301system was7:3. Infrared spectroscopy showed that the principle of the reaction of VersaticlO with nickel and cobalt was ion exchange of carboxyl hydrogen ion and metal ions. In the extraction process of Cyanex301, apart from the ion exchange of-SH band and metal ions, there was a strong coordination effect between the P=S band in Cyanex301and metal ions which might lead to the difficutl stripping of the loaded Cyanex301. However, the coordination effect was reduced significantly in the Versaticl0-Cyanex301system, so that the stripping became easier. |
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