含铀灰渣的多级逆流浸出工艺技术

Multi-Stage Countercurrent Leaching Process of Uraniferous Ash

在铀产品及核燃料元件制造过程中,各种可燃性废物经裂解焚烧减容处理而产生大量含铀灰渣。通过对含铀灰渣进行多级逆流浸出,考察灰渣预处理方式、灰渣粒度、浸出级数以及超声作用对溶解浸出效率的影响,结果表明:(1)含铀灰渣的预处理方式对溶解浸出过程有明显的影响,120 ℃烘干预处理灰渣比800 ℃煅烧预处理灰渣更易于浸出;(2)灰渣粒度对浸出过程无明显影响;(3)含铀灰渣经一级浸出后,铀质量分数从20%左右降至1.5%以下,二级浸出渣铀质量分数降至0.8%左右,三级浸出灰渣铀质量分数变化不大;(4)超声能明显强化含铀灰渣的溶解浸出过程,使一级浸出渣铀质量分数从1.26%降至0.34%,超声强化二级浸出渣铀质量分数可降至0.12%。

During the manufacture of uranium products and nuclear fuel elements, a large amount of uraniferous ash was produced due to pyrolysis incineration of various combustible wastes. In this paper, multi-stage leaching process of uraniferous ash was researched and the effects of ash pretreatment, particle size, leaching times and ultrasonic on the leaching ratio were investigated. The following results are found:(1) the pretreatment method of uraniferous ash has obvious effect on leaching process and drying (120 ℃) pretreatment is superior to the calcination pretreatment ash (800 ℃),(2) the particle size of uraniferous ash has no obvious effect on the leaching process,(3) after first leaching of uraniferous ash, the mass fraction of uranium decreases from about 20% to below 1.5%, reaches to about 0.8% after secondary leaching, and almost remains the same after tertiary leaching,(4) ultrasonic can significantly enhance the leaching of uraniferous ash to reduce the mass fraction of residual uranium from 1.26% to 0.34% after first leaching, and further reduces the value to 0.12% after secondary leaching.