Mechanism of CO<SUB align="right">2 sequestration by high-alkaline red mud: conversion of katoite
Zelin Su, Dongbo Wang, Xianqing Huang, Xiang Li, Xin Yu, Ying Huang, Qingge Feng
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.