Secondary reaction mechanism of leaching process of calcium aluminate slag

SiO 2 in calcium aluminate slag exists in the form of γ -2CaO·SiO 2 which is more stable than β -2CaO·SiO 2 . However, it is decomposed by sodium carbonate solution during leaching process, leading to the secondary reaction. The extent of secondary reaction and reaction mechanism of calcium aluminate slag were studied using XRD. The results show that the decomposition rate of γ -2CaO·SiO 2 increases with the increase in leaching time and sodium carbonate concentration. The main products of secondary reaction are the mixture of hydrogarnet and sodium hydrate alumina–silicate. SiO 2 concentration rises firstly and then drops with the increase of leaching temperature. XRD results indicate that the stable product of secondary reaction at low temperature is hydrogarnet. But hydrogarnet is transformed into sodium hydrate alumina–silicate at high temperature.