从高硅锅炉烟尘中回收锌试验

Experiment on recovery of zinc from high-silicon boiler dust

新疆某锌冶炼企业回转窑锅炉烟尘硅含量高,浸出液会形成大量胶体硅,固液分离困难。基于此,利用可溶硅在低酸条件下易浸出的特点,开发了高硅锅炉烟尘二段浸出回收锌+中和除硅联合工艺。结果表明,控制一段浸出终点pH=2时,锌、铁、可溶硅浸出率分别为61.23%、3.21%和95.23%,能有效实现硅的分离;一段浸出液经石灰和除硅剂中和除硅,硅脱除率在90%以上;一段浸出渣经高温高酸浸出后,可将渣中锌含量降至1.43%,实现了高硅锅炉烟尘中锌的高效回收。本工艺实现了硅的高效选择性浸出,抑制了铁的浸出,避免石灰中和除硅过程中生成大量的氢氧化铁胶体。

The rotary kiln boiler dust of a zinc smelter in Xinjiang had a high silicon content, which resulted in the formation of a large amount of colloidal silica in the leachate, causing difficulty in the separation of the solid and liquid. Based on this situation, a combined process of two-stage leaching and recovery of zinc from high-silicon boiler dust + neutralization for silicon removal was developed by taking advantage of the easy leaching feature of soluble silicon under low acid conditions. The results showed that an effective separation of silicon was achieved and the zinc, iron and soluble silicon leaching rates were 61.23%, 3.21% and 95.23% respectively when the endpoint pH value of the first-stage leaching was controlled at 2.0;the silicon removal rate of the first-stage lechate reached above 90% after neutralization by lime and silicon-removal agent for silicon removal;the zinc content in the residue was reduced to 1.43% after high-temperature and high-acid leaching of the first-stage leachate, accomplishing an efficient recovery of zinc in the high-silicon boiler dust;a high-efficiency selective leaching of silicon was realized through the process, the leaching of iron was inhibited and the formation of an unexpected amount of ferric hydroxide colloid was also avoided during lime neutralization for silicon removal.