Oceanic cobalt-rich crusts contain many valuable metals including Co, Ni, Cu, and Mn, of which Co and Ni are scarce metal resources on terrestrial land. Co, Ni, Cu, and Mn in cobalt-rich crusts can be efficiently extracted by the ammonium sulfate roasting-water leaching (ARWL) process, but separating and recovering Co and Ni from the leaching solution containing high concentrations of Mn is a challenging problem. In this study, a combination of sulfide precipitation and P507–Cyanex 272 synergistic extraction is proposed for the separation and recovery of Co and Ni from the ARWL solutions of oceanic cobalt-rich crusts. Under the optimum sulfide precipitation conditions, Co and Ni were precipitated with 99.85% and 99.63% efficiency, respectively, while Mn was coprecipitated with only .79% efficiency. The Co–Ni mixed sulfides were dissolved by dilute sulfuric acid under oxidative conditions to obtain a solution containing 12.584 g/L Co, 11.012 g/L Ni, and a small amount of Mn. Subsequently, Co and Mn were extracted from this solution using P507–Cyanex 272 synergistic extraction, the single-stage extraction efficiencies of Co and Mn were 95.76% and 99.73%, respectively, and the coextraction efficiency of Ni was 3.02%, under the conditions of a feed solution pH of 3.0, an extractant saponification degree of 70%, a total extractant concentration of 20% (P507 to Cyanex 272 ratio of 3:7), and an O/A ratio of 1.1:1. The results of the thermodynamic study showed that the reaction of Co extraction by this mixed extraction system was exothermic. Ni in the organic phase was washed with an H₂SO₄ concentration of .12 mol/L, followed by stripping of Co and Mn with an H₂SO₄ concentration of .6 mol/L. Mn in the stripping solution was removed by oxidative precipitation with (NH₄)₂S₂O₈, after which the Co₃O₄ product was obtained by precipitation with (NH₄)₂C₂O₄ and calcination. Similarly, NiC₂O₄·2H₂O can be obtained from the raffinate by (NH₄)₂C₂O₄ precipitation. Finally, a flowsheet was developed for the separation and recovery of Co, Ni, Cu, and Mn from the ARWL solutions of oceanic cobalt-rich crusts. The study provides a promising scheme for the recovery of various valuable metals from deep-sea cobalt-rich crusts or manganese nodules.

中文翻译：

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硫化物沉淀和P507-Cyanex 272协同萃取从大洋富钴结壳硫酸铵焙烧水浸出液中高效分离回收Co和Ni

大洋富钴结壳中含有Co、Ni、Cu、Mn等多种有价金属，其中Co、Ni是陆地稀有金属资源。硫酸铵焙烧水浸（ARWL）工艺可以有效提取富钴结壳中的Co、Ni、Cu和Mn，但从高浓度Mn浸出液中分离回收Co和Ni是一个具有挑战性的问题。在这项研究中，提出了硫化物沉淀和P507-Cyanex 272协同萃取相结合的方法，用于从大洋富钴结壳的ARWL溶液中分离和回收Co和Ni。在最佳硫化物沉淀条件下，Co和Ni的沉淀效率分别为99.85%和99.63%，而Mn的共沉淀效率仅为0.79%。在氧化条件下用稀硫酸溶解Co-Ni混合硫化物，得到含有12.584 g/L Co、11.012 g/L Ni和少量Mn的溶液。随后，采用P507-Cyanex 272协同萃取从该溶液中萃取Co和Mn，在此条件下，Co和Mn的单级萃取效率分别为95.76%和99.73%，Ni的共萃取效率为3.02%。原料液pH为3.0，萃取剂皂化度为70%，总萃取剂浓度为20%（P507与Cyanex 272比例为3:7），O/A比例为1.1:1。热力学研究结果表明，该混合萃取体系萃取Co的反应是放热反应。_{用0.12mol/L浓度的H 2} SO ₄洗涤有机相中的Ni ，然后用0.6mol/L浓度的H ₂ SO _{4反萃取Co和Mn。用(NH 4} ) ₂ S ₂ O ₈氧化沉淀去除反萃液中的Mn ，然后用(NH ₄ ) ₂ C ₂ O ₄沉淀并煅烧得到Co ₃ O ₄产物。_{类似地，可以通过(NH 4} ) ₂ C ₂ O ₄沉淀从萃余液中得到NiC ₂ O ₄ ·2H _{2 O。}最后，开发了从大洋富钴结壳 ARWL 溶液中分离和回收 Co、Ni、Cu 和 Mn 的流程图。该研究为从深海富钴结壳或锰结核中回收各种有价金属提供了一个有前途的方案。