The invention provides desiliconized
fly ash and a preparation method and application thereof. The preparation method of the desiliconized
fly ash comprises the following steps: 1) mixing high-
alumina fly ash and first alkali lye and then carrying out primary normal-pressure
silicon removal, and carrying out liquid-
solid separation to obtain a first desiliconized liquid and a first
filter cake; 2) washing and starching the first
filter cake with an acid solution, and carrying out liquid-
solid separation on the washing and starching product to obtain an acid-
pickling filter cake and an acid-
pickling filtrate; and 3) mixing the acid-
pickling filter cake and second alkali lye and then carrying out secondary normal-pressure
silicon removal, and carrying out liquid-
solid separation to obtain a second desiliconized liquid and desiliconized fly ash. According to the above preparation method of desiliconized fly ash, high-
alumina fly ash is used as the
raw material, and a two-stage normal-pressure
silicon removal and acid-pickling combined mild wet method is adopted for silicon removal. Thus, reaction pressure is decreased, cost of investment in equipment is reduced, desiliconization efficiency and
alumina-silica ratio of desiliconized fly ash are increased, and it is beneficial to subsequent extraction of alumina.