Abstract:To address large amount of calcium addition and residue and low alumina recovery of lime sinter process, a new process to extract alumina from desiliconized fly ash by low-calcium lime sinter process was proposed. Effects of different ratios of calcium oxide to alumina (C/A) and alkali to alumina (N/A) on sintering behavior, pulverization and alumina leaching performance of clinker were investigated. The results show that main phases of fly ash clinkers by low-calcium lime sinter process are 12CaO?7Al2O3 and γ-2CaO?SiO2, with some 2CaO?Al2O3?SiO2, CaO?Al2O3, 2Na2O?3CaO?5Al2O3 and β-2CaO?SiO2. Increasing C/A ratio is helpful for conversion of 2CaO?Al2O3?SiO2 to 12CaO?7Al2O3 and γ-2CaO?SiO2, which improves alumina leaching and pulverization performance of clinker. Increasing N/A ratio can promote conversion of 2CaO?Al2O3?SiO2 to 12CaO?7Al2O3 and 2Na2O?3CaO?5Al2O3, which improves leaching performance of alumina, but over N/A ratio rises β-2CaO?SiO2 content in clinker and reduces pulverization performance of clinker. Alumina leaching efficiency of clinker sintered at 1 350 ℃ for 1 h is 93.29% with C/A=1.40 and N/A=0.10, and clinker possesses a good pulverization.