古冶炼废渣环境毒性鉴别

Environmental toxicity identification of ancient smelting slag

对古冶炼废渣中重金属的腐蚀性和浸出毒性进行分析,并对废渣中重金属在不同pH条件下的浸出行为进行探讨。结果表明:废渣pH呈弱碱性,残留重金属含量很高,Zn+Pb平均含量高达6.97%,但废渣中重金属以残渣态为主,浸出毒性很低,对环境的危害潜力明显减弱,表明采用总量法来预测废渣中重金属的环境危害是不确切的。在极酸性和极碱性条件下,废渣中重金属的浸出量明显增大。在pH<3时,Zn、Pb、Cr和Cd的浸出量均达到极大值。在pH>12时,Zn、Pb、Cr的浸出量增大,但浸出量比酸性条件下小。在中性条件下,Zn、Pb、Cr和Cd的浸出量最小。在正常降雨条件下,古冶炼废渣对环境的危害能力已降低到较低水平,可按一般工业固体废物的要求进行处置。

The corrosion and extraction toxicity of heavy metal in ancient smelting slag is analyzed.Leaching behavior of heavy metal in smelting slag is discussed through extraction toxicity test of different pH values.The results show that the pH of smelting slag is alkalescence,the heavy metal content is high and the average content of heavy metal（zinc plus plumbum）is up to 6.97%.However,most of heavy metal in smelting slag is in residual state.Its extraction toxicity is low and potential harm for environment is obviously weakened.It indicates that forecasting heavy metal＇s potential harm for environment in smelting slag by totalizing method is not accurate.The leachable quantities of heavy metals significantly increase in extremely acidic and alkaline condition.The leachable quantities of Zn,Pb,Cr and Cd are all up to maximum when pH3.The leachable quantities of Zn,Pb and Cr all increase when pH〉12,but the extracting amount is lower than that in acidic condition.The leachable quantity of Zn,Pb,Cr and Cd is minimal in neutral condition.Under normal rainfall conditions,potential harm for environment of ancient smelting slag is decreased to a lower level.It can be treated according to the requirement for general industrial solid wastes.