碱浸钢丝污泥热处理后的重金属形态及浸出特性

为了分析碱浸钢丝污泥热处理后的重金属形态及浸出特性，以ALRS（碱浸钢丝污泥）为研究对象，通过批处理试验，研究了热处理温度对ALRS中Pb和Zn浸出特性及其化学形态的影响，并运用重金属综合毒性指数模型（STI）对热处理ALRS中Pb、Zn的综合毒性进行了评估.结果表明:高温热处理使得ALRS的物相成分发生改变，钙-铁复合氧化物分解，形成单一铁氧化物及钙氧化物.热处理使得ALRS中Pb、Zn总量有一定程度增加，而其浸出量随处理温度升高而降低，Pb、Zn最大释放量与总量的最大比值仅为0.52%.BCR连续提取法结果表明，ALRS中Pb、Zn形态主要是以残渣态和可氧化态形式存在，酸溶态含量较低，分别为2.84%和8.94%.经热处理后，Pb和Zn的残渣态含量（F4）明显增加，酸溶态（F1）、可还原态（F2）、可氧化态（F3）3种形态含量减少，两种重金属的稳定态含量与不稳定态含量比值（F3+F4）/（F1+F2）]分别在900和800℃时取得最大值（22.86和10.61）.综合毒性评估结果表明，STI值由原状样品的0.065减至900℃下样品的0.046，重金属综合毒性和生态风险显著降低.研究显示，热处理可增加碱浸剩余污泥中Pb、Zn的稳定性，降低其生态风险. 

Heavy Metals Forms and Leaching Characteristics of ALRS with Heat Treatment

In order to analyze the speciation and leaching characteristics of heavy metals in the alkali leaching steel wire sludge (ALRS) with heat treatment, the effects of heat treatment temperature on the leaching characteristics and chemical forms of Pb and Zn of ALRS were evaluated by batch experiments. The integrated toxicities of Pb and Zn of ALRS with heat treatment were investigated by the synthesis toxicity index model (STI) as well. The results showed that the phase composition of ALRS converted from calcium iron-complex oxides into iron oxide and calcium oxide, and the total concentration of Pb and Zn in ALRS gained a certain increase after high-temperature treatment. The leaching amount decreased with increasing temperature, and the maximum leaching ratio was only 0.52%. According to the results of BCR speciation analysis, Pb and Zn in ALRS are mainly in the form of residual and oxidizable fractions. The contents of residual fractions of Pb and Zn increased significantly after heat treatment, while the contents of acid-soluble, reducible and oxidizable fractions decreased. The maximum values of Pb and Zn for (F3+F4)/(F1+F2) were separately 22.86 and 10.61 under 900 and 800℃ accordingly. The results of comprehensive toxicity assessment showed that the value of STI of samples reduced from 0.065 at room temperature to 0.046 at 900℃, which indicated that the comprehensive toxicity and ecological risk of heavy metals reduced significantly. The study shows that heating process can increase the stability of Pb and Zn in ALRS and reduce their ecological risk.