Method For Recycling Smelting Slag Of AB_ 5 Type Rare Earth Based Hydrogen Storage Alloy

To recycle smelting slag of AB₅ type rare earth-based hydrogen storage alloy, three different recovery methods based on pyrometallurgical technology were studied.Method one: RE-Ni-Co alloy and rare earth oxides were recyclied by method of hydrothermal and acid dissolution-reduction and diffusion-arc melting.First, alloy enrichment was obtained in the process of hydrothermal and acid dissolving which rare earth oxides were separated partly from smelting slag powders. Then, alloy powders was obtained in the process of reduction-diffusion which the rest rare earth oxides was reduced into AB₅ type alloy.In this process calcium granules were added into alloy enrichment. Finally, RE-Ni-Co alloy was obtained in the process of arc melting. The separated rare earth oxides′purity is over then 99 percent. As raw materials, the separated rare earth oxides can be used to pruduct rare earth metals. The recycled alloy has low impurity contents,so it can be used for the smelting of AB₅ type rare-earth hydrogen storage alloy as basic raw material. This method achieve the recycling of the smelting slag of AB₅ type rare earth-based hydrogen storage alloy.Method tow: Ni-Co alloy and rare earth oxides slag were recycled by method of selective oxidation atmosphere of H₂/H₂O-melting. Under the 800～900℃and selective oxidation atmosphere of H₂/H₂O, RE,Al,Mn and other active elements of smelting slag transformed into oxidation states, and relatively inert elements such as Ni, Co still keeped in a simple substance states. Adding slagging elements such as SiO₂,Al₂O₃ etc to the smelting slag after it was treated by the process of the selective oxidation.It was treated by well mixing before melting under 1550～1600℃.Finally, Ni-Co alloy and REO-SiO₂-Al₂O₃-MnO₂ slag were obtained.The recycled Ni-Co alloy has a high purity,so it can be used to product AB₅ type rare earth-based hydrogen storage alloy as raw material. Rare earth oxides slag has high reuse value with a content of 44.15 percent of rare earth oxides.Method three: Fe-Ni-Co alloy and rare earth oxides slag were recycled by method of direct reduction/oxidation-melting. Adding smelting slag to iron concentrate with a reasonable mass ratio, then it was treated with reaction cylinders drict reduction/oxidation. When the mass ratio of iron concentrate and smelting slag is 100:25,keeping the mixed material at 1200℃for 1.5 hours,then spongeiron was obtained.In the process of reaction cylinders drict reduction/oxidation,iron oxide of the mixed material was reducted to Fe simple substance and Ni,Co still keep in simple substance states,at the same time the relatively active elements such as RE,Al,Mn etc were oxidized to oxidation state.Smelting the spongeiron, Fe-Ni-Co alloy and REO-SiO₂-Al₂O₃-MnO₂ slag were obtained. REO-SiO₂-Al₂O₃-MnO₂ slag was the conjugate of rare earth oxides and gangue in the iron concentrate.The recycle rate of Ni and Co is over 99 percent. Fe-Ni-Co alloy can be used as raw material for special steel smelting. Rare earth oxides slag has high reuse value with a content of 48.27 percent of rare earth oxides. Three methods were offered to recycle smelting slag of hydrogen storage alloy. Basic information and theoretical basis for industry provides of smelting slag recycly were provided.So this paper has significant application prospects.