Mg2+ leaching and CO2 sequestration of magnesium tailings enhanced by external field coupled with pretreatment

• Published in: Journal of environmental chemical engineering 2024-10, Vol.12 (5), p.113613, Article 113613
• Main Authors: Liu, Jingfei, Chen, Huichao, Zhang, Menghan
• Format: Article
• Language: English
• Subjects: CO2 sequestration; Impregnation calcination; Indirect mineral carbonation; Microwave; Ultrasound
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2024.113613

The magnesium tailings, whose main phase composition is serpentine [Mg3Si2O5(OH)4], has lower reactivity than common minerals and solid waste, but rich magnesium content. It is of great significance for CO2 emission reduction and ecological environment protection to solve the problem of low leaching rate and carbon sequestration efficiency of Mg2+ in the tailings. The strengthening effect of external field (microwave and ultrasound) and pretreatment (impregnation-calcination) on leaching of magnesium tailings and its mechanism were studied, which significantly improved the leaching efficiency of Mg2+ in tailings. The idea of CO2 heterophase absorption and sequestration was put forward, and the efficient of CO2 mineralization was achieved by using the leaching product, magnesium-rich leaching solution. The results showed that pretreatment of impregnation and calcination and external field (microwave and ultrasound) could promote the leaching reaction of magnesium tailings. Reaction mechanism analysis showed that microwave can accelerate the reaction rate, pretreatment and ultrasound induction can reduce the adverse effect of product layer on the reaction, and promote the leaching of Mg2+. The optimum leaching parameters (acetic acid concentration of 4 mol/L, temperature of 80 °C, liquid-solid ratio of 20, tailings particle size