| The rare earth hydrogen storage alloy has excellent dynamic performance,stability,and high hydrogen storage capacity,and is the earliest hydrogen storage alloy for largescale industrial application.With the extensive use of rare-earth hydrogen storage materials,a large amount of rare earth hydrogen storage alloy wastes are generating,containing a large amount of valuable metal resources,especially the rare earth,nickel,and cobalt metal elements therein.In this paper,the cobalt,nickel,and rare earth elements were recovered using the hydrometallurgical process,and the following results are obtained.After pretreatment of rare earth hydrogen storage alloy scraps,the method of adding sodium carbonate to roasting in high temperature-water leaching” was adopted and aluminum elements were removed by water leaching in the form of sodium aluminate after adding sodium carbonate to roasting in high temperature.The single factor experiments of sodium carbonate content,calcination temperature,calcination time water leaching temperature and water leaching time on the leaching rate of aluminum were investigated.The results show that the aluminum removal rate can reach of 98.65.The hydrochloric acid was used to leaching the cobalt,nickel,manganese and rare earth elements of the water leaching slag obtained from removing aluminum.The single factor experiments of the amount of hydrogen peroxide,the concentration of hydrochloric acid,the ratio of liquid to solid,the leaching temperature,the leaching time and the stirring speed were investigated.The results show the leaching rate of manganese reaching 99.78%,the leaching rate of rare earth elements reaching 99.04%,the leaching rate of cobalt reaching 98.54%,and the leaching rate of nickel reaching 98.47%.The “ammonia separation” method was used to separate the cobalt,nickel,manganese and rare earth elements from the leaching solution.Ammonia was added dropwise to adjust the pH.The cobalt and nickel elements form soluble ammonia complexes.While the manganese and rare earth elements converted to the hydroxide precipitates to complete the separation of cobalt,nickel,manganese and rare earth elements.The single factor experiments of the pH,ammonium chloride concentration,reaction time and stirring speed were investigated.The results show the yield of cobalt element reaching 99.03%,the yield of nickel element reaching 99.70%.The oxidation-excellent solubility method was used to separate the rare earth elements from the ammonia separation slag.Firstly,manganese hydroxide was oxidized to the hydrated manganese dioxide which is hardly soluble in dilute nitric acid by hydrogen peroxide.And then dilute nitric acid was used to leach the rare earth elements from the ammonia separation slag.The single factor experiments of hydrogen peroxide addition amount,oxidation time,oxidation stirring speed,concentration of excellent dissolved nitric acid,excellent solid-to-liquid ratio,excellent dissolution time,and excellent dissolution speed were investigated.The results show the leaching rate of manganese no more than 0.10%,the leaching rate of rare earth elements reaching 99.99% and the mass fraction of rare earth elements in solution reaching 99.99%.The oxidation-extraction method was used to separate the cobalt and nickel elements from the ammonia separation solution.Firstly,bivalent cobalt ammonia complex was oxidized to the inert trivalent cobalt complexes which is hardly extracted by ammonium persulfate.And then the oxidized solution was extracted by D2 EHPA to complete the separation of the cobalt and nickel.The single factor experiments of pH value,oxidant ammonium persulfate addition amount,ammonium chloride addition amount,extraction time,extraction temperature,comparison,stripping agent sulfuric acid concentration,stripping time were investigated.The results show the extraction percentage of cobalt less than 0.1%,the percentage of nickel more than 90%,the content of nickel in the organic phase reaching 99.99%,and obtaining nickel sulfate by striping extraction. |
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