Refining and Utilization of Rare Earth Elements from Phosphors in Waste Fluorescent Lamp

研究了荧光灯废液中稀土组分的分离和酸浸行为，建立了稀土回收体系。首先通过重介质分离、水力分离、气动分离、重分离和浮选等工艺，研究了磷污泥中稀土组分和磷酸钙的分离特性。新开发的重介质分离方法对稀土磷光粉的分离效率、回收率和品位均最高，其次为气动分离。磷污泥经气动分离后，稀土成分在各种酸性溶液和氢氧化钠溶液中浸出。对于浸出液中可溶组分的回收，采用氢氧化物和草酸盐沉淀等处理工艺回收稀土组分。采用气动分离法、硫酸浸出法和草酸盐沉淀法对荧光灯废磷污泥中的钇和铕进行了有效回收。最终回收率为65%，纯度为98.2%。采用多级逆流萃取法从浸出液中分离和回收稀土元素是可行的。研究了废荧光灯处理中磷渣合成Y_20_3: Eu^<3+>的合成方法和烧结条件。Y_20_3: Eu^<3+>在最佳条件下经1.5 mol/l硫酸浸出、氢氧化物和草酸盐沉淀、冻干和烧结等后续处理工艺合成；烧结温度为1200℃，烧结时间为40小时，添加1%硼酸钡作为助熔剂。以磷渣为原料合成Y_20_3: Eu^<3+>粉体，获得晶粒尺寸在0.2 μm以上的良好晶体结构，50%粒径在5 ~ 6 μm范围内。结果表明，由磷污泥合成的Y_20_3: Eu^<3+>粉体可以作为稀土红色荧光粉使用。少

The separation and acidic leaching behaviors of phosphor sludge have been examined to establish the recycling system of rare earth components contained in fluorescent lamp waste. At first, separation characteristic of rare earth components and calcium phosphate in phosphor sludge was investigated by heavy media separation, hydro separation, pneumatic separation, gravity separation and flotation. Newly developed heavy media separation method showed highest separation efficiency, recovery and grade of rare earth phosphors and the pneumatic separation was the second result. After pneumatic separation of phosphor sludge, rare earth components were leached in various acidic solutions and sodium hydroxide solution. For recovery of soluble component in leaching solution, rare earth component was recovered by treatment processes such as hydroxide and oxalate precipitations. Yttrium and europium from phosphor sludge contained in fluorescent lamp waste were recovered effectively by three process … More es of pneumatic separation, sulfuric acid leaching and oxalate precipitation methods. Their recovery was finallv about 65%, and its purity was 98.2%. It was also found that separation and recovery of rare earth elements from the leaching solution by multistage countercurrent extraction were possible.Synthesis method and sintering conditions have been examined to establish the synthesizing Y_20_3 : Eu^<3+> from phosphor sludge in processing waste fluorescent lamp. Y_20_3 : Eu^<3+> were synthesized by 1.5 mol/l sulfuric acid leaching, subsequent treatment processes such as hydroxide and oxalate precipitations, freeze-dry, and sintering in optimum condltions ; sintering temperature is 1200℃, sintering time is 40 hours, with addition of 1% barium borate as the flux. Y_20_3 : Eu^<3+> powder synthesized from phosphor sludge, was obtained well crystal structure of above 0.2 μm crystal size, and with 50% particle size in the range of 5-6 μm. It was found that Y_20_3 : Eu^<3+> powder synthesized from phosphor sludge by this work could be used substantially as a red rare earth phosphor. Less