Utilisation of fly ash in the manufacture of zeolites

[摘要] Disposal of CFA is a problem of increasing concern, due to the environmental impact of CFA. Beneficiation processes such as the RockTron process are capable of producing various value-added products, and the Delta product is apt for use in the synthesis of zeolites. The current study explores hydrothermal Si extraction, fusion assisted extraction and a novel microwave fusion process with a performance comparable to the fusion process. The extraction process was optimised for the Delta ash, and compared to other ashes and rice husk ash. In the optimisation of the crystallisation process, the influence of sodium aluminate addition on the properties of zeolites was examined. The effects of alkalinity, sodium source and salt concentration were investigated using XRD, SEM, AAS, CEC and PSD. A concurrent decrease in Si and Al in the crystallisation solution was observed as amorphous material was consumed. This crystal growth phase occurs earlier with higher concentrations of sodium aluminate and NaCl. Addition of NaCl can improve crystallinity, yield and CEC and decrease particle size. Optimised results demonstrated good repeatability. The best estimated yield was 264 g/kg FA, with a CEC of 4.8 meq/g. Buoyant zeolites were synthesised through seeding of the crystallisation process with cenospheres. The products consisted of 77% cenospheres and 23% zeolite.

[发布机构] University:University of Birmingham;Department:School of Chemical Engineering

[关键词] Q Science;QD Chemistry