Study on the interaction between inherent minerals of coal with refuse derived fuel (RDF) during co-firing

[Display omitted] •Co-firing of coal with refuse derived fuel (RDF) was investigated.•The formation of K/Ca-Al-Si generated more sticky particles in the gas bulk.•The adsorption of sticky particles depressed the yields of fine particles. In this paper, refuse derived fuel (RDF) and bituminous coal were co-fired to investigate the particulate matter (PM) yields and the interaction between the inherit minerals in a lab-scale drop tube furnace (DTF). The PM1-10 yields during the co-firing of coal and RDF dramatically decreased by 16.29 %∼28.5 % of the combustion of coal alone. In addition, methane auxiliary combustion inhibited the PM1 yields by 7.95 % at air atmosphere. The Si-rich minerals in coal interreacted with the organic alkali (earth) metals in RDF, massively generating sticky particles with high liquid amount of K-Al-Si and Ca-Al-Si, promoting the transformation of fine grains into coarser mode. Moreover, it was proved that both methane auxiliary combustion and co-firing can reduce the emission of fine particles. The additional heat accelerated the burn of the char at the early stage of combustion, providing adequate time for the interaction between the inorganic species. Through thermodynamic equilibrium calculations of 1500 ∼ 3000 fly ash grains, it was found that co-firing increased the formation of sticky particles by 64.8 %∼70.3 %, resulting in a significant enhancement in capturing fine particles and Na, K vapor. Therefore, the co-firing of coal with RDF offers a promising approach to realize the harmless and resourceful treatment of municipal solid waste (MSW), and inhibit land resource losses caused by landfill