Study on mechanism and kinetics of iron removal by chlorination roasting of coal gangue

Abstract

Utilizing the abundant kaolin resources within coal gangue is economically beneficial, although the iron-containing phase in the minerals hampers the value of its utilization. In the present study, CaCl2 served as the chlorination agent for iron removal from coal gangue through chlorination roasting. The study revealed that when the roasting temperature is below 800 °C, CaCl2 decomposes into HCl and reacts with the iron content to form chloride, which then volatilizes. Comparatively, when the roasting temperature exceeds 800 °C, CaCl2 will decompose to produce HCl and Cl2 to accelerate the volatilization of iron. Through non-isothermal kinetic analysis, the apparent activation energy for iron removal by chlorination roasting of coal gangue was found to be 82.42 KJ/mol, and the pre-exponential factor was 6329.3 s−1. Correspondingly, isothermal kinetic analysis revealed the apparent activation energy of 84.2 KJ/mol and a pre-exponential factor of 6310.7 s−1. The optimal reaction kinetic mechanism function for iron removal through chlorination roasting of coal gangue was identified as the F3 chemical reaction order model via above kinetic analysis. The integral took the form g(α) = (1-α))2–1.