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Mineral carbonation to sequester CO₂ with concurrent metal sulfidization Wang, Fei

Abstract

Global warming is an urgent issue all over the world and mineral carbonation for CO₂ sequestration is one of the best methods to permanently store CO₂ gas. To make the mineral carbonation process profitable, it is suitable to combine with metal sulfidization for valuable metal recovery by utilizing the carbonation process since there are increasing demands of valuable metals around the world as well. This dissertation established the theoretical system for the potentially successful development of mineral carbonation for permanent CO₂ storage and utilization for metal sulfidization. The fundamental mechanisms and kinetics of mineral carbonation of olivine have been elucidated. The most important factors affecting the mineral carbonation process were the temperature, CO₂ partial pressure (PCO₂), specific surface area, aqueous ionic strength (I) and addition of sodium bicarbonate. The effects of these parameters on the mineral carbonation of olivine have been quantified. The mechanism can vary under different conditions and mainly depended on PCO₂ and the aqueous I. The increase of the aqueous I and PCO₂ can help prevent passivation of the mineral carbonation reaction by preventing formation of a silica-rich layer or a uniform carbonate layer respectively. Once the aqueous I and PCO₂ are high enough, the mineral carbonation of olivine is always controlled by chemical reaction of the dissolution of olivine. Under the chemical reaction control, a quantitative kinetic model has been developed, which can be used to predict the mineral carbonation efficiency and also the requirements of carbonation conditions. It is possible to utilize the mineral carbonation process for recovery of the released valuable metal from the dissolution of olivine by in-situ sulfidization. The key for the in-situ metal sulfidization is to continuously supply sulfide ions in the mineral carbonation system in order to selectively convert the released valuable bivalent metal ions to recoverable metal sulfides.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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