粉煤灰中汞的水浸脱除研究

粉煤灰中存在重金属汞，在环境中具有迁移的可能性，限制了粉煤灰在生态修复领域的利用。基于汞的赋存状态及其特性，提出了粉煤灰水浸脱汞新思路，采用单因素试验对脱汞新工艺进行了工艺条件的优化，并提出了原位合成水合氧化铝吸附剂的方法对脱汞废液进行净化。结果表明，在优化条件下，即温度为75℃、脱汞时间为2 h、液固比为5时，粉煤灰中汞的脱除率可达80%以上，汞含量可降至约0.1 μg/g，远低于土壤环境质量标准（GB 15618—2018）中土壤污染风险筛选值，大幅降低了粉煤灰生态利用的环境风险。原位合成的吸附剂对脱汞废液中汞的脱除率达到85%左右，净化液中汞的浓度降至2.267 μg/L，低于企业水污染物排放标准限值。 

Study on the Removal of Mercury from Fly Ash by Water Leaching

There is mercury in fly ash. The mercury in fly ash is easy to migrate in the environment, which limits the use of fly ash in the field of ecological restoration. Based on the occurrence states and characteristics of mercury, a new idea of removing mercury from fly ash by water leaching was proposed. Single factor experiments were used to optimize the process conditions of this new mercury removal process. And the method of in-situ synthesis of hydrated alumina adsorbent was proposed to purify the waste liquid of mercury removal. The results showed that under optimized process conditions, i.e. the temperature was 75 ℃, the mercury removal time was 2 h and the liquid-solid ratio was 5, the mercury removal rate can reach above 80% and the mercury content in fly ash can be reduced to about 0.1 μg/g. It was far below the risk screening value of soil pollution in GB 15618—2018, which greatly reduced the environmental risk of fly ash ecological utilization. The removal rate of mercury in waste liquid by the in-situ synthesized adsorbent reached about 85%. After purification, the concentration of mercury in the solution was reduced to 2.267 μg/L, which was lower than the limit value of enterprise water pollutant discharge standard.