煤气化渣除杂富铝制备聚合氯化铝实验研究OA北大核心CSTPCD

Coal gasification slag is a solid waste produced from coal gasification process.With the extensive promotion and application of coal gasification process,the substantial coal gasification slag production threatens the ecological environment and hampers the development of the coal chemical industry.To facilitate the resourceful and industrialized utilization of coal gasi-fication slag,taking coal gasification slag as the research object,its mineral occurrence form and chemical composition were analyzed,and a comprehensive approach to prepare poly aluminum chloride(PAC)from alumina-rich acidic leach solution was proposed.Firstly,using the differ-ence of reactivity between each element in coal gasification slag and acid solution,Fe2+,Ca2+and a small portion of Al3+were leached out under low acid system.Subsequently,the selective sepa-ration of calcium and iron salts from the slag was achieved based on ion precipitation pH,enric-hing the aluminum content in the acid-treated slag.Then,utilizing aluminum-rich acidic slag as the raw material,the acid leaching was used to prepare the precursor of PAC.Moreover,the effects of the amount of calcium aluminate powder added,the polymerization temperature,the polymerization time on the performance of the product and flocculation effect were examined.The results show that in 60%of the theoretical acid consumption,Al3+,Fe2+,Ca2+are leached from the slag.By adjusting the pH of the reaction solution to 3.5 and facilitating selective precip-itation of Al3+,the removal ratio of calcium and iron reaches 84.06%and 79.79%,respectively,with Al2O3 mass fraction increasing from 10.84%up to 14.38%;Further dissolving the alumi-num-rich acidic slag with the theoretical acid amount resultes in an alumina mass concentration of 28.4 g/L;Adding calcium aluminate powder to acid solution at a ratio of 10 g∶100 mL and poly-merizing at 80℃ for 2.5 h produces PAC that meets the quality of GB/T 22627-2022.FTIR and XRD analysis on the PAC product confirm that the synthesized product is polymerized alumi-na chloride.The product is applied to simulated wastewater,and the turbidity removal ratio is as high as 92.90%.