Study On Recycling Technology Of Rare Earth Polishing Powder And Application Performance

The ceria-based polishing powder is a kind of outstanding polishing materialsas high-efficiency，good accuracy as well as friendly operation condition. It iswidely applied in high accuracy glass products. Recycling the waste residue ofrare earth polishing powder not only have economic value, but also save energy aswell as protect the environment. This paper analyzed the compose of waste residueof rare earth polishing powder first, and effect of different leaching agents that usedfor extracting rare earth element form waste residue were studied, then oxalic acidsolution was used as the precipitant to prepare rare earth oxalate sediment. Thecomposition and morphology of rare earth oxalate sediment calcined at differenttemperatures were investigated. Finally the polishing performance of relative powderswas studied. The results were as following:1.Sulfuric acid is the most appropriate leaching agent. The leaching rate of rareearth elements was above93%when the ratio of materials vs sulfuric acid was1:1.75，reacted at150。C for4hours;2.When pH value ranged from0.5to1.05by sing aqua ammonia to adjust thesolution of rare earth oxalate suspension, the solubility of rare earth oxalate changedfrom9.67g/L to2.87g/L, the obtained rare earth oxalate particles were globular andabout10μm. It lost crystal water at115℃and decomposed to rare earth oxides at390。C;3.The main phases of samples was cubic crystal CeO₂when calcined between550℃-950℃，it did not crystallize completely at550℃，the sample was cubicfluorite structure at850。C，the diffraction peaks of the calcined sample was furtherenhanced at950。C； when the temperature ranged from550。C to950。C，the grainssize increased froml8nm to50nm，meanwhile the lattice distortion degree wasdecreasing gradually and the lattice constant was reducing slightly;4.The polishing efficiency of powders increased significantly with the increaseof calcined temperatures and holding time, the polishing performance was368nm/minwhen sample calcined at950℃for3hours, the form of grains was spheroid. The total rare earth oxides for obtained powders were over98%and the CeC>2content wasover70%.