Abstract:Desilication fly ash clinker was digested to obtain different concentration of sodium aluminate solution by controlling ratio of liquid to solid. Secondary reaction during clinker digestion process was analyzed by analyzing solution composition and solid phase composition in crude sodium aluminate solution under different leaching time. The results show that with increase of aluminate concentration and prolongation of leaching time, concentrations of alumina and silicon in aluminate solution decrease, contents of Al2O3 and Na2O in calcium silicate slag rise, and dissolution rates of Al2O3 and Na2O drop gradually. For calcium silicate content higher than 50% in desilication fly ash clinker, it is suggested that concentration of sodium aluminate solution be controlled at 100~120 g/L, and separation time of liquid and solid be controlled within 180 min. Reaction products and reaction process change with initial aluminate concentration with prolongation of leaching time under different initial aluminate concentration. Main products of dissolved solid phase include hydrogarnet, sodium-silicon residue, calcium silicate and a trace amount of calcite.