Non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution

Carbonation decomposition of hydrogarnet is a significant reaction of the calcification–carbonation new method for alumina production by using low-grade bauxite. In this work, non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution was studied by high-pressure differential scanning calorimetry (HP-DSC) at different heating rates of 2, 5, 8, 10, 15 and 20 K·min− 1, respectively. The activation energy (Ea) was calculated with the help of isoconversional method (model-free), and the reaction mechanism was determined by the differential equation method. The calculated activation energy of this reaction was 115.66 kJ·mol− 1. Furthermore, the mechanism for decomposition reaction is Avrami–Erofeev (n = 1.5), and the decomposition process is diffusion-controlled.

Graphical abstractNon-isothermal decomposition kinetics of synthetic hydrogarnet in sodium carbonate solution was studied by high-pressure differential scanning calorimetry (HP-DSC). The activation energy (Ea) of decomposition reaction is 115.66 kJ·mol− 1, which calculated by the isoconversional method. The mechanism for decomposition reaction is Avrami-Erofeev n = 1.5) determined by the differential equation method, and the decomposition process is diffusion-controlled. The kinetic equation was presented.Figure optionsDownload full-size imageDownload as PowerPoint slide