Coupled mechanisms of reaction kinetics, gas emissions, and ash mineral transformations during combustion of AlCl3-conditioned textile dyeing sludge
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Though commonly used in the dewatering of textile dyeing sludge (TDS) before its incineration, chemical conditioning has yet to be evaluated in terms of its impact on the reaction mechanisms, emissions, and ash minerals. This study combined experiments and equilibrium simulations to disentangle the interaction mechanism among the combustion behaviors, gas emissions, ash minerals of TDS conditioned with(out) three blend ratios of the AlCl3 conditioner. The use of the AlCl3 conditioner slightly improved the performance of the combustion stage of volatiles and chars. No significant effect of AlCl3 conditioner was detected on the kinetic mechanism of its main combustion stage best elucidated by the nth-order and diffusion models. SO2 was the main evolved gas whose reduction between 600 and 800 degrees C was attributed to its increased retention rate by CaO from the decomposition of CaCO3. Aluminum compounds acted as a stimulator in SO2 emission between 800 and 1000 degrees C since the formation of calcium aluminosilicates. At above 1060 degrees C, CaSO4 decomposed rapidly, thus almost completely releasing inorganic S. This study supplies new insights into pollution 'controls on the combustion of TDS conditioned with Al salt coagulant.