Thermodynamic analysis of secondary reactions in the clinker leaching process

Thermodynamic computations and discussion of some reactions involved in the clinker leaching process are described. The stability of 2CaO·SiO2 in sodium aluminate liquor, the reactions between calcium silicate and sodium aluminate liquors, the reactions between hydrogarnet and NaOH and Na2CO3, and the hydration of 2CaO·SiO2 have all been analyzed in thermodynamic terms. The results indicate that the stability subsequences of 2CaO·SiO2 and calcium silicate in the three alkaline solutions are dissimilar. The decomposition tendency of hydrogarnet in NaOH and Na2CO3 solutions increases with elevation of temperature. The stability of hydrogarnet with large saturation coefficient is higher than that with smaller saturation coefficient. Hydrogarnet is more stable in NaOH solution than in Na2CO3 solution. At low temperatures, hydration of calcium orthosilicate to afford 2CaO·SiO2·1.17H2O and 4CaO·3SiO2·1.5H2O is thermodynamically most favorable.