Technological Conditions Of Recovering Rare Earth Metals From An Abandoned Rare Earth Polishing Powder

The waste of rare earth polishing powder contains the valuable metallic ele ments such as lanthanum, cerium, if can be recycled will has important environme ntal significance and economic value. This paper takes the waste rare earth polishin g powder as raw material, design of concentrated sulfuric acid leaching, rare eart h sodium sulfate double salt recovery of rare earth elements, separation and recover y of rare earth metal processes such as process flow. Through the single factor e xperiments and orthogonal experiment, the optimal conditions of the technology of each step in the process was experimentally studied, the main conclusions are as fo llows:(1) The optimized reaction technological conditions of sulfuric acid leaching process were obtained as follows:reaction time 100min, reaction temperature270℃, acid powder ratio 2.6. The experiment was repeated under this condition, the leaching rate of rare earth metal elements is 98.4%.(2) The optimized reaction technological conditions of Rare earth sodium sulfate double salt recovery of rare earth metal element process were obtained as follows: System of pH 2.0, anhydrous sodium sulfate and rare earth elements of the ratio of 5.2:1, reaction temperature 65 ℃, reaction time 120 s. The experiment was repeated under this condition, the recovery rate of rare earth metal elements is 95.03%.(3) The optimized technological conditions of cerium hydroxide preparation were obtained as follows:Hydrogen peroxide and ammonia molar ratio of 1.2:1, the decomposition temperature 92℃,the decomposition time 42min. The experiment was repeated under this condition, Cerium oxide rate was 98.46% in cerium hydroxide, cerium average yield was 98.76%.(4) Using oxalic acid precipitation in the form of recovering lanthanum nitrat e solution of lanthanum, the yield is 92.03%.(5) The preparation of samples for pure phase face-centered cubic cerium oxide and hexagonal lanthanum oxide.