Complete heavy metal removal from fly ash by heat treatment: Influence of chlorides an evaporation rates
Complete heavy metal removal from fly ash by heat treatment: Influence of chlorides an evaporation rates
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DOI：
10.1021/es960059z
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发表时间：
1996-11-01
影响因子：
11.4
通讯作者：
Struis, RPWJ
中科院分区：
文献类型：
--
作者：
Jakob, A;Stucki, S;Struis, RPWJ
热处理是一种很有前途的垃圾焚烧残留物的净化和惰性化方法。因此，重金属化合物的蒸发具有重要意义。这是这项工作的目标，通过分析蒸发速率，主要的热化学反应的重金属与飞灰的其他成分，相对于挥发。为此，在670-1000摄氏度的温度范围内，用来自城市固体废物（MSW）焚烧厂的飞灰以及合成粉末混合物进行实验。镉，铜，铅，锌蒸发率可以准确地描述一个简单的一阶速率定律和速率系数，它本身遵循指数温度依赖性类似的Arkalius方程。的程度（完整性），以及重金属的蒸发率显着影响飞灰中所含的氯化物，主要是氯化钠。与模型基板的实验表明，重金属Zn和Cu在飞灰中，这是最不挥发性的研究组之间，主要是作为氯化物存在。它们的蒸发是通过改变氧化物/氯化物平衡来完成的，如果过剩的氯，以NaCl的形式存在。重金属蒸发可能受到形成重金属二氧化硅/氧化铝化合物的反应的限制。
Thermal treatment is a promising way for the decontamination and inertization of residues from waste incineration. The evaporation of heavy metal compounds thereby is of great significance. It is the goal of this work to identify, by analyzing evaporation rates, the predominant thermochemical reactions of the heavy metals with other constituents of fly ash, with respect to volatilization. To this end, experiments were performed with fly ash from a municipal solid waste (MSW) incineration plant as well as with synthetic powder mixtures in the temperature range of 670-1000 degrees C. The rates of Cd, Cu, Pb, and Zn evaporation can be described accurately by a simple first-order rate law and a rate coefficient which itself follows an exponential temperature dependence analogous to the Arrhenius equation. The degrees (completeness) as well as the rates of evaporation of the heavy metals are markedly influenced by chlorides contained in the fly ash, largely as NaCl. Experiments with model substrates indicate that the heavy metals Zn and Cu in fly ash, which are the least volatile among the group investigated, are predominantly present as chlorides. Their evaporation is completed by shifting the oxide/chloride equilibrium if surplus chlorine, e.g., in the form of NaCl, is available. The heavy metal evaporations are probably limited by reactions that form heavy metal silica/alumina compounds.