Method For Recycling Smelting Slag Of AB₅Type Rare Earth-Based Hydrogen Storage Alloy

To recycle smelting slag of AB5type rare earth-based hydrogen storage alloy, threedifferent recovery methods based on pyrometallurgical technology were studied.Method one: RE-Ni-Co alloy and rare earth oxides were recyclied by method ofhydrothermal and acid dissolution-reduction and diffusion-arc melting.First, alloy enrichmentwas obtained in the process of hydrothermal and acid dissolving which rare earth oxides wereseparated partly from smelting slag powders. Then, alloy powders was obtained in the processof reduction-diffusion which the rest rare earth oxides was reduced into AB5type alloy.In thisprocess calcium granules were added into alloy enrichment. Finally, RE-Ni-Co alloy wasobtained in the process of arc melting. The separated rare earth oxides′purity is over then99percent. As raw materials, the separated rare earth oxides can be used to pruduct rare earthmetals. The recycled alloy has low impurity contents,so it can be used for the smelting of AB5type rare-earth hydrogen storage alloy as basic raw material. This method achieve the recyclingof the smelting slag of AB5type rare earth-based hydrogen storage alloy.Method tow: Ni-Co alloy and rare earth oxides slag were recycled by method of selectiveoxidation atmosphere of H2/H2O-melting. Under the800～900℃and selective oxidationatmosphere of H2/H2O, RE、Al、Mn and other active elements of smelting slag transformedinto oxidation states, and relatively inert elements such as Ni, Co still keeped in a simplesubstance states. Adding slagging elements such as SiO2、Al2O3etc to the smelting slag afterit was treated by the process of the selective oxidation.It was treated by well mixing beforemelting under1550～1600℃.Finally, Ni-Co alloy and REO-SiO2-Al2O3-MnO2slag wereobtained.The recycled Ni-Co alloy has a high purity,so it can be used to product AB5type rareearth-based hydrogen storage alloy as raw material. Rare earth oxides slag has high reuse valuewith a content of44.15percent of rare earth oxides.Method three: Fe-Ni-Co alloy and rare earth oxides slag were recycled by method of directreduction/oxidation-melting. Adding smelting slag to iron concentrate with a reasonable massratio, then it was treated with reaction cylinders drict reduction/oxidation. When the mass ratioof iron concentrate and smelting slag is100:25,keeping the mixed material at1200℃for1.5hours,then spongeiron was obtained.In the process of reaction cylinders drictreduction/oxidation,iron oxide of the mixed material was reducted to Fe simple substance andNi、Co still keep in simple substance states,at the same time the relatively active elementssuch as RE、Al、Mn etc were oxidized to oxidation state.Smelting the spongeiron, Fe-Ni-Co alloy and REO-SiO₂-Al₂O₃-MnO₂slag were obtained. REO-SiO₂-Al₂O₃-MnO₂slag was theconjugate of rare earth oxides and gangue in the iron concentrate.The recycle rate of Ni and Cois over99percent. Fe-Ni-Co alloy can be used as raw material for special steel smelting. Rareearth oxides slag has high reuse value with a content of48.27percent of rare earth oxides.Three methods were offered to recycle smelting slag of hydrogen storage alloy. Basicinformation and theoretical basis for industry provides of smelting slag recycly wereprovided.So this paper has significant application prospects.