Vitrification of municipal solid waste incineration fly ash using biomass ash as additives

Abstract

Thermal melting is an energy-costing solution for stabilizing toxic fly ash discharged from the air pollution control system in the municipal solid waste incineration (MSWI) plant. In this paper, two different types of biomass ashes are used as additives to co-melt with the MSWI fly ash for reducing the melting temperature and energy cost. The effects of biomass ashes on the MSWI fly ash melting characteristics are investigated. A new mathematical model has been proposed to estimate the melting heat reduction based on the mass ratios of major ash components and measured melting temperature. Experimental and calculation results show that the melting temperatures for samples mixed with biomass ash are lower than those of the original MSWI fly ash and when the mass ratio of wood ash reaches 50%, the deformation temperature (DT), the softening, hemisphere temperature (HT) and fluid temperature (FT) are, respectively, reduced by 189°C, 207°C, 229°C, and 247°C. The melting heat of mixed ash samples ranges between 1650 and 2650 kJ/kg. When 50% wood ash is mixed, the melting heat is reduced by more than 700 kJ/kg for the samples studied in this paper. Therefore, for the vitrification treatment of the fly ash from MSW or other waste incineration plants, wood ash is a potential fluxing assistant.

Synergistic effect of polyvinyl chloride and coal ash on thermal separation of heavy metals from MSWI fly ash through molten salt process

“…However, fly ash (FA) is a second pollutant produced from MSWI, and it contains a large number of heavy metals, salts, dioxins and other harmful substances, which are classified as hazardous waste and need to be treated safely (Chen et al, 2019; Ohbuchi et al, 2020; Vehlow et al, 2006). The treatment of FA is primarily safe landfill after solidification, including cement solidification (Tang et al, 2020; Yakubbu et al, 2018a), melting solidification (Alhadj-Mallah et al, 2015; Gao et al, 2021) and chemical stabilization (Liu et al, 2016; Wang et al, 2015). Due to the shortage of land resources and the increasing availability value of FA, FA disposal technology has been mainly focussed on resources recovery technology in recent years.…”

Effect of additives on melting temperature and energy consumption of municipal solid waste incineration fly ash

“…The ash melting characteristics affect the treatment temperature during the vitrification process. Ash fusibility is closely related to ash composition, which mainly consists of oxides and chlorine (Alhadjmallah et al, 2015;Gao et al, 2020;Gong et al, 2017;Jiao et al, 2016;Liao et al, 2018;Lin, 2006;Ma et al, 2017a;Tian et al, 2012), as shown in Table 1. Calcium oxide (CaO) and silicon dioxide (SiO 2 ), which are the two most common compounds in FA, fluctuate in the range of 3.25%-53.7% and 1.5%-52.65%, respectively.…”