Synthesis of β-Tricalcium Phosphate and Calcium Hydroxyapatite Using Waste Incineration Fly Ash

β-tricalcium phosphate (Ca3(PO4)2: β-TCP) and calcium hydroxyapatite (Ca10(PO4)6(OH)2: Hap) were synthesized from waste incineration fly ash (Fa). The Fa was washed with H2O and heated at 1000°C in air as a pretreatment. The pretreatment increased CaO molar fraction by the dissolution of NaCl and KCl as well as the decomposition of CaCO3 and Ca(OH)2. The β-TCP was obtained by the reaction of pretreated Fa and dicalcium phosphate dihydrate (CaHPO4·2H2O: DCPD) at 1000°C in air. The best molar ratio DCPD/(Ca in pretreated Fa) for synthesis of β-TCP was found to be 1.5. The Hap was prepared using β-TCP obtained from Fa by treating it in NaOH solution at 90°C for 18h. When the pretreated Fa was treated in H3PO4 solution at pH=9.0 and 85°C, the CaO in Fa were completely dissolved to form Hap. Based on these results, we suggest that the Fa is a useful calcium source for the synthesis of β-TCP and Hap.