采用机械活化浸出的方法从废弃荧光粉中浸出稀土元素,考查了液固比、硫酸浓度、浸出时间对稀土氧化物浸出率的影响,并对浸出渣进行了碱式焙烧—二段浸出.研究结果表明,Y2O3、Eu2O3浸出率随液固比增大略有降低,随硫酸浓度的提高和浸出时间的延长显著提高,最高达99.66％和91.69％;CeO2、Tb4O7浸出率远小于Y2O3、Eu2O3,仅为32.97％和32.79％,其浸出率受到镁铝尖晶石的酸解浸出的影响;碱式焙烧破坏了镁铝尖晶石的结构,显著提高了CeO2、Tb4O7的浸出率,浸出渣中Y2O3、Eu2O3、CeO2 、Tb4O7的二段浸出率分别达到98.83％、93.71％、81.78％和88.46％,此时稀土氧化物总回收率最大为96.21％;对浸出终渣进行了XRD、SEM和EMPA分析,发现浸出渣呈絮状结构,颗粒大小为1 μm～10 μm,没有检出稀土元素.
The mechanical activation leaching of REOs from waste fluorescent powder was conducted in this work.The effects of influent factors such as liquid-solid ratio,sulphuric acid concentration and leaching time were investigated.The alkali roasting followed by secondary leaching of residue was studied.The phase and elemental composition,and the microstructure of final leach residue were characterized by using X-ray diffraction (XRD),scanning electron microscope (SEM) and electron probe microanalysis (EMPA).The experimental results show that the leaching rate of Y2O3 and Eu2O3 are increase with the increasing of sulphuric acid concentration and leaching time.The maximum leaching rate of CeO2 and Tb4O7 are 99.66％ and 91.69％.The leach of CeO2 and Tb4O7 are very difficult due to tough structure of magnesium aluminate spinel.The leaching rate of CeO2 and Tb4O7 are merely 32.97％ and 32.79％.The magnesium aluminate spinel in residue was destroyed by alkali roasting,resulting in significant increase of leaching rate of CeO2 and Tb4O7.The secondary leaching rate of Y2O3,Eu2O3,CeO2,Tb4O7 and the total recovery of REOs are 98.83％,93.71％,81.78％,88.46％ and 96.21％ correspondingly and respectively.The final leach residue has flocculent loose microstructure.The particle size is about 1 μm ～ 10 μm.Almost no rare earth element presented in leach residue.
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