(General session) High-temperature materials processing / Hydrometallurgy

[1K0301-06-05] CO₂ capture by porous MgO obtained from alkali fusion of ferronickel slag

○Fakhreza Abdul^{1[Student presentation: Doctoral course]}, Ken Adachi², Hsing-jung Ho¹, Atsushi Iizuka¹, Etsuro Shibata² (1. Department of Environmental Studies for Advanced Society, Graduate School of Environmental Studies, Tohoku University, 2. Center for Mineral Processing and Metallurgy, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University)

Chairperson: 岸本　章宏（京都大学）

Keywords:CO2 reduction, CO2 sequestration, alkali pretreatment, solid waste utilization, sustainable process

Laterite nickel ore, the main raw material for FeNi production, has complex mineralogy and many impurities. Therefore, the FeNi production process yields a substantial amount of solid by-products (FeNi slag), necessitates a large amount of energy for processing, and emits a significant amount of CO₂ into the environment. So far, the utilization of FeNi slag is only limited to applications in the civil and construction fields. This is due to the stability of the main mineral in FeNi slag, which is generally in the form of Mg₂SiO₄ or MgSiO₃. This research aims to activate FeNi slag by transforming MgSiO₃/Mg₂SiO₄ into porous MgO. Thus, porous MgO can be further used for CO₂ capture. As a result, porous MgO transformation was successfully carried out through alkali fusion of FeNi slag using NaOH at 500 ^oC, a mass ratio of slag-to-NaOH of 1:2, and duration for 4 hours followed by water washing. The resulting MgO-rich materials can then be used to capture CO₂ in an autoclave reactor at 150 ^oC, pCO₂ of 12 bar, water-to-sample ratio of 10 mL/g, time for 1 hour, and stirring at 500 rpm with a carbonation efficiency of about 73%. Through the alkali fusion-water washing-pressurized carbonation process route, CO₂ uptake of 0.17 g CO₂/g FeNi slag can be achieved.