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Recovery of Metal Resources from Wastes using Thermal Plasma

利用热等离子体从废物中回收金属资源

基本信息

批准号：
05680387
负责人：
KANZAWA Atsushi
金额：
$ 1.28万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05680387/
关键词：
thermal plasma wastes resource recovery ceramics flyash reaction mechanisms リサイクル水素

项目摘要

The purpose of the research is to teat flyash produced from a incinerator and to recover metal resources from the flyash using a reactive thermal plasma. As a fundamental study, five kinds of metal oxides were treated by the thermal argon plasma with the addition of four kinds of gases. The reaction mechanisms between the reactive plasma and metal oxides were estimated by considering the analyzes of products and residual sample, and calculation of Gibbs' free energy change. The results showed that the reaction passes were classified according to the following reaction ; thermal decomposition in the sample, surface reaction, thermal decomposition in gas phase, reaction in gas phase. The further study was carried out to elucidate the reaction mechanisms. Magnesia, silica and alumina were chosen as a metal oxide and hydrogen was added into the thermal argon plasma. In the treatments of magnesia and silica, hydrogen addition enhanced the decrease in the oxide samples. The weight decreasing rate was in proportion to the root of hydrogen concentration and the intensity of hydrogen atom emission, suggesting hydrogen atom took part in the reaction. Magnesium was recovered from the plasma treatment of magnesia, however silicon was not recovered from silica. According to the consideration of the experimental results, equilibrium compositions, and surface temperature, the reaction mechanisms was proposed including the deoxidation and evaporation. In alumina treatment, no weight change in the sample was observed because alumina was thermodynamically stable at estimated surface temperature. The study will be continued using mixed metal oxide samples and finally the recovery process in the plasma treatment of flyash will be proposed.

本研究的目的是利用反应热等离子体对焚烧炉产生的飞灰进行处理，并从飞灰中回收金属资源。作为基础性研究，我们用四种不同的气体对五种金属氧化物进行了热氩等离子体处理。通过对反应产物和残留样品的分析以及吉布斯自由能变化的计算，对反应等离子体与金属氧化物的反应机理进行了估计。结果表明，反应途径按样品中的热分解、表面反应、气相中的热分解、气相中的反应进行分类。进一步研究了反应机理。选择氧化镁、二氧化硅和氧化铝作为金属氧化物，并将氢加入到热氩等离子体中。在氧化镁和二氧化硅的处理中，氢的加入增强了氧化物样品的减少。失重率与氢原子发射强度和氢浓度的根成正比，说明氢原子参与了反应。从氧化镁的等离子体处理中回收镁，但是没有从二氧化硅中回收硅。根据实验结果、平衡组成和表面温度，提出了反应机理，包括脱氧和蒸发。在氧化铝处理中，没有观察到样品的重量变化，因为氧化铝在估计的表面温度下是热稳定的。研究将继续使用混合金属氧化物样品，最后将提出在等离子体处理粉煤灰的回收过程。