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Immobilization by sulfuration of waste heavy metals

废弃重金属的硫化固定化

基本信息

批准号：
13450316
负责人：
MATSUDA Hitoki
金额：
$ 0.83万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

The present study is concerned with a novel method to immobilize and deposit heavy metals contained in fly ash from waste incineration facilities.The toxic heavy metals such as lead and zinc are present as soluble compounds in fly ash such as metal chlorides and oxides. This study was based on the fact that heavy metals naturally exist as insoluble sulfides and that asphalt is water-repellent. We propose the physical and chemical immobilization of waste heavy metals by mixing with asphalt, sulfur and alkaline agents-sodium hydroxide and calcium hydroxide, in a bi-axial kneader heated at 403-523K.Calculations on the Gibbs' free energies showed that sulfuration of heavy metals resulted from the formation of either sodium sulfide or calcium sulfide via the reaction of sulfur with alkaline agents. Experimental results from XRD analysis of soluble metal compounds mixed with sulfur and alkaline agents also indicated that soluble metal compounds were convertable to insoluble metal sulfides only if either sodium sulfide or calcium sulfide is initially formed. It was found that the addition of sulfur and sodium hydroxide into fly ash at 403K led to the sulfuration of heavy metals. Similarly, the addition of sulfur and calcium hydroxide at 523K brought about sulfuration of heavy metals. The results of the leachability test for the treated fly ash by the proposed immobilization method indicated that leaching of heavy metals in fly ash was suppressible.

本研究涉及一种固定和沉积废物焚烧设施飞灰中所含重金属的新方法。铅和锌等有毒重金属以金属氯化物和氧化物等可溶性化合物存在于飞灰中。这项研究基于以下事实：重金属以不溶性硫化物天然存在，并且沥青具有防水性。我们提出通过在403-523K加热的双轴捏合机中与沥青、硫磺和碱性剂氢氧化钠和氢氧化钙混合来物理和化学固定废弃重金属。对吉布斯自由能的计算表明，重金属的硫化是由于通过硫化钠或硫化钙的形成而导致的。硫与碱性试剂反应。对与硫和碱性试剂混合的可溶性金属化合物进行 XRD 分析的实验结果也表明，只有在最初形成硫化钠或硫化钙时，可溶性金属化合物才能转化为不溶性金属硫化物。结果发现，在403K的温度下向飞灰中添加硫和氢氧化钠会导致重金属的硫化。类似地，在523K下添加硫和氢氧化钙会导致重金属硫化。通过所提出的固定化方法处理的飞灰的浸出率测试结果表明，飞灰中重金属的浸出受到抑制。