Conversion of waste incineration fly ash into zeolite A and zeolite P by hydrothermal treatment

Zeolities A and P were successfully prepared by hydrothermal treatments at 60-120°C in the presence of NaOH solutions from waste incineration fly ash as a starting materials, pretreated with acid in addition to water washing and heating. The pretreatment was an important process to reproducibly convert fly ash into zeolites A and P. The relations between product fiels of zeolites A and P and hydrothermal conditions were examined. Consequently, zeolites A and P were successfully synthesized by treatments with 1.0-2.0 M NaOH solutions at 60°C for 20-48 h and with 0.5-2.0 M solutions at 80-100°C for 20-48 h, as major products, respectively. The treatment led the generation of sodalite with increasing NaOH concentration. The hydrothermal products exhibited removal characteristics for NH₄⁺ ions, and their uptake amounts were found to depend on zeolites A and P yields.