Thermodynamic simulation of α-spodumene calcination with Na2SO4

In this research work, the calcination reaction of a spodumene (LiAlSi2O6) with Na2SO4 through thermodynamic simulation using the Equilib module included in the Fact Sage 8.2 software was studied. The LiAlSi2O6:Na2SO4 molar ratios (RM) analyzed were: 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.85, 1:1, and 1:1.5 in the temperature range from 50°C to 1200°C and 1 atmosphere of pressure determining the chemical species in equilibrium every 50 °C through Gibbs energy minimization. The most stable chemical species formed in all RMs were: Li2SO4, NaAlSi3O8, NaAlSiO4 and LiNaSO4. The maximum % percentage yield (% PY) for the Li2SO4 specie was 50% in the solid state starting at 500°C and in the liquid state at temperature ≥ 900°C for the 1:1 RM with an excess of Na2SO4 of 15%. The results obtained from the present study allowed us to propose the reaction mechanism of the calcination process of a spodumene with Na2SO4.