Composition modification and plasma vitrification of bottom ash from industrial hazardous waste incineration

Abstract

Industrial hazardous waste (IHW) incineration bottom ash (BA) contains high-content acidic oxides and a limited amount of basic oxides. This contributes to the vitrification of the BA sample, although it causes a high melting temperature and viscosity. Unfortunately, basic fluxing agents play a negative role in the durability of glassy slag. Hence, the industrial BA melting process requires a comprehensive and accurate composition modification method. In this study, the basicity, complete liquid phase temperature, and viscosity-temperature performance of a BA sample were investigated. The BA sample was melted using a thermal plasma system. Furthermore, environmental sound quality analysis was performed, including the toxicity characteristic leaching procedure and acid loss rate. The results indicate that the BA sample may be directly vitrified, although the melting temperature and viscosity need to be modified. Comprehensively, it was found that 15% CaO addition is the most suitable choice. The BA composition modification sample melted completely, slagging smoothly, transformed mostly to the vitrification state, and the index values of the environmental sound quality analysis were dramatically reduced. It has been proven that appropriate composition modification can not only guarantee the stable BA melting process but also favor the vitrification and solidification of heavy metals.