Making ash slag harmless and metal recovery from secondary volatilized fly ash

研究了粉煤灰熔渣和含重金属合成渣中重金属的洗脱性能。一些结果如下。粉煤灰的熔融处理和玻璃化处理对防止重金属的溶解是有效的，但也有少数例外。在粉煤灰中加入二氧化硅并保持高温对防止重金属的溶解是有效的。洗脱试验后pH值的变化影响洗脱性能。富碱金属粉煤灰提高了洗脱ph值，炉渣热处理对重金属的洗脱有改善作用。用硫酸和盐酸对二挥发粉煤灰进行了浸出试验，并对灰的浸出性能进行了研究。一些结果如下。二挥发粉煤灰中Zn、Pb、Cu、Fe可通过盐酸溶液浸出，Pb不能通过硫酸溶液浸出。浸出碱含量高的灰分，需要大量的酸。采用胶结法从硫酸浸出液中回收铜。通过pH控制胶结后，铁和锌可从溶液中回收。用乙酸钠溶液从硫酸浸出渣中浸出铅。

Elution property of heavy metal from fly ash molten slag and synthesized slag containing heavy metals were investigated. Some of results are follows.Melting treatment and vitrification of fly ash was effective for prevention of dissolution of heavy metals but with minor exception. Adding silica to fly ash and holding high temperature was valid with prevention of dissolution of heavy metals. Elution pH changes after elution test that affect elution property. Alkali metal rich fly ash rises elution pH. Heat treatment of slag had an effect for improve the elution of heavy metals.The leaching of secondary volatilized fly ash with sulfuric acid and hydrochloric acid has been conducted, and leaching properties of ash were investigated. Some of results are follows.Zn, Pb, Cu and Fe were leached from secondary volatilized fly ash by hydrochloric acid solution, but Pb was not leached from the ash by sulfuric acid solution. For leaching the ash containing high amount of alkali content, a large quantity of acid was needed.Cu was recovered from the leaching solution after sulfuric acid leaching by cementation. Fe and Zn were recovered from the solution after cementation by pH control. Pb was leached from the residue after sulfuric acid leaching by sodium acetate solution.