从废弃CRT荧光粉中回收稀土的研究

Recovery of rare earth element from waste cathode ray tube phosphors by concentrated sulfuric acid directional transformation-water leaching

废弃CRT荧光粉是一种含有稀土钇和铕的二次资源,具有较高的回收价值。本研究采用浓硫酸定向转型-水浸的方法高效回收废CRT荧光粉中的稀土资源。通过浓硫酸定向转型,使废弃CRT荧光粉中的稀土和硫酸根结合形成稀土硫酸盐,而负二价的硫与浓硫酸反应形成单质硫气体,避免了剧毒气体硫化氢的产生,之后稀土硫酸盐经过水浸后进入溶液,达到了高效绿色回收稀土的目的。研究表明,在最优条件:酸样比8:5 mL/g,转型温度85℃,转型时间30 min,液固比10:1 mL/g,水浸温度85℃,水浸时间30 min下,稀土钇和铕的平均浸出率达到了99.77%和99.24%,并获得了含钇8.26 g/L和含铕0.57 g/L的浸出液。

A process for recovering both Eu and Y from the discarded cathode ray tube(CRT)display was introduced.The developed process involved a directional transformation of waste CRT phosphors with concentrated sulfuric acid followed by leaching with water.Rare earth metal ions combined with sulfate to form rare earth sulfates and then were extracted by water leaching,while S_2~-was oxidized to form sulfur,which was volatilized in gaseous form,thus avoiding the formation of the highly toxic gas H_2S.This study showed that in the optimized conditions,the ratio of concentrated sulfuric acid to sample was 8:5 mL/g and transformation time for 30 min under 85℃,the liquid-to-solid ratio was 10:1 mL/g and leaching time was 30 min under 85℃.The leaching solution with Y concentration of 8.26 g/L and Eu concentration of 0.57 g/L was obtained and the average leaching efficiencies of Y and Eu were 99.77%and 99.24%,respectively.