Original Article

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

¹ School of Mining and Technology, Liaoning Technical University, Fuxin 123000, Liaoning, PR China
² College of Science, Liaoning Technical University, Fuxin 123000, Liaoning, PR China
³ School of Materials Science and Engineering, Liaoning Technical University, Fuxin 123000, Liaoning, PR China
⁴ Batang Branch of Huadian Jinsha River Upstream Hydropower Development Co, Ganzi 626700, Sichuan, PR China

^* e-mail: zhaoxs210@163.com

Received: 21 June 2023
Accepted: 31 January 2024

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.