Title: Mechanism of CO₂ sequestration by high-alkaline red mud: conversion of katoite

Authors: Zelin Su; Dongbo Wang; Xianqing Huang; Xiang Li; Xin Yu; Ying Huang; Qingge Feng

Addresses: School of Resources, Environment and Materials, Guangxi University, Nanning-530004, Guangxi, China ' School of Resources, Environment and Materials, Guangxi University, Nanning-530004, Guangxi, China ' School of Resources, Environment and Materials, Guangxi University, Nanning-530004, Guangxi, China ' School of Resources, Environment and Materials, Guangxi University, Nanning-530004, Guangxi, China ' School of Resources, Environment and Materials, Guangxi University, Nanning-530004, Guangxi, China ' School of Resources, Environment and Materials, Guangxi University, Nanning-530004, Guangxi, China ' School of Resources, Environment and Materials, Guangxi University, Nanning-530004, Guangxi, China

Abstract: Red mud (RM) is an alkaline solid waste, which can be carbonised and neutralised by sequestrating carbon dioxide (CO₂). Here, the CO₂ sequestration capacity of red mud was quantitatively characterised by elemental analyser, and the effects of liquid-solid ratio (2:1-10:1), reaction time (0-300 min), reaction pressure (2-12 bar) and reaction temperature (room temperature - 130°C) were studied in detail. In addition, both the red mud before and after carbonation were characterised by XRD, FT-IR, SEM and laser particle size analyser. The results showed that CO₂ could be sequestrated by red mud due to the mineral phase transformation of alkaline substances, which was that katoite converted to calcite and other substances with dissolving CO₂ and leaching Ca²⁺ in water medium.

Keywords: red mud; carbon dioxide; sequestration; carbonation; transformation; alkaline substances; mechanism; katoite; conversion; calcite.

DOI: 10.1504/IJGW.2020.110293

International Journal of Global Warming, 2020 Vol.22 No.2, pp.160 - 173

Received: 20 Dec 2019
Accepted: 30 Mar 2020
Published online: 13 Oct 2020 *

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