Influence of Ca(OH)2 addition amount on zircon alkali fusion decomposition process

With the zircon sand to sodium hydroxide mass ratio of 1.0: 1.2, and the Ca(OH)2 additive amount of 0.2%, 0.4%, 0.6%, 0.8% and 1.0% to zircon amount separately, the influence of Ca(OH) 2 on zircon alkali fusion decomposition process was studied. The composition of the reactant and heat changes of the reaction system were analyzed by X-ray diffraction (XRD) and differential scanning calorimetry-thermal gravimetric analysis (DSC-TG). It was found that when the additive amount of Ca(OH)2 reached 1.0%, the decomposition rate of zircon increased up to a maximum value of 96.4%. When the temperature reached 590°C, the process of alkali fusion decomposition occurred a violent exothermic reaction, and the main products of zircon alkali fusion decomposition were Na2ZrO3 and Na2SiO3. In addition, the results showed that the optimal sintering temperature and sintering time were about 750°C and 30 min respectively to decompose zircon with caustic soda and Ca(OH)2 additive.