ACEME: Direct Aqueous Mineral Carbonation of Dunite Rock

Abstract

This research explores the use of serpentinized dunite (which is comprised of 61% lizardite) as a feedstock for aqueous mineral carbonation. In initial experiments, dunite was heat‐activated (630°C, 4 h), adopting a procedure which is similar to that used for serpentinite to enhance their carbonation reactivity. Heat‐activation converts crystalline lizardite mineral into an amorphous, reactive phase, and the carbonation of this heat‐activated material resulted in a magnesite yield of 55% compared to 27% obtained with raw dunite under the same reaction conditions. The formation of silanol nests occurred during carbonation of heat‐activated dunite as deduced through FTIR and TGA‐MS analyses. Samples of dunite were also heat‐transformed at high temperatures (800°C, 3 h) to convert lizardite into forsterite, and these samples were also studied as potential feedstocks for mineral carbonation. Heat‐activated dunite was found to engender much higher magnesite yields compared to heat‐transformed dunite (forsterite rich) and raw dunite. This study suggests that during heat‐activation of dunite, as it is for lizardite, conditions should be maintained to avoid forsterite formation. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13075, 2019