Influence of Re-Crystallization and Magnetic Separation Procedure on Refuse Slag

• Main Authors: Shih-chih Cheng, 鄭世智
• Other Authors: Kuen-sheng Wang
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/70962284526895687546

碩士 === 國立中央大學 === 環境工程研究所 === 94 === Abstract Along with the gradual increasing yield of the refuse residues, the appropriate management and treatment of the residues has become an urgent environmental protection problem in this country. The present study aims at the high temperature treatment of the bottom ash and fly ash, with a self-developed laboratory-scale plasma furnace, and then verifying the various influences on the properties of refuse slag through different procedures, such as the analysis of residues properties, residues composition adjusting, air-cooling and recrystalization and magnetic separation etc., and finally performing a comprehensive evaluation of such influences by the exploration of literatures as well as experimental results, so as to establish the pre-processing procedure for the refuse melt, the operational conditions of recrystalization and recovery strategy. In light of the study results, it is revealed that the dissolution ratio of heavy metals contained in the incinerator residues, after the implementation of the melting process, is much lower than the regulatory standard. The hardness of recrystalization slag is dramatically higher than that of magnetic separation slag and air cooling slag, therefore it is suitably used as pavements; and the magnetic separation slag belongs to the glassy slag, which is suitably used as the raw material of glass. Both the air cooling slag and magnetic separation slag don’t have a clear crystalline structure, whereat the recrystalization slag mainly consists of Gehlenite (Ca2Al2SiO7) and Akermanite (CaMg(SiO7), however, the strength of Wollastonite (CaSiO3) is dramatically much lower than others, in addition to its crystalline strength will be decreasing further along with the longer time of heat treatment. The optimum temperature maintaining time for the air cooling slag is one hour, and at this moment the crystalline structure of slag will have the maximum strength. While comparing the values, it is found that the value acquired from the alkali silica reaction of recrystalization slag, magnetic separation slag and air cooling slag is at least 1.0 larger than the Sc/Rc ratio of the slag, wherein the ratio of magnetic separation slag lays at the border between the non-hazardous area and potential hazardous area, however the values of both air cooling slag and recrystalization slag are then lay in the non-hazardous area.