Thermochemical monitoring of brucite carbonation using passive infrared thermography

Abstract

Heat generation from passive CO2 sequestration in mafic/ultramafic mining wastes and tailings remains a poorly explored facet of ambient mineral carbonation. In this work, heat generation and carbon dioxide uptake during the carbonation of brucite were monitored in a specially-designed dual-cell carbonation reactor replicating environmental conditions. The reactor was instrumented with a passive infrared thermography imaging system combined with CO2 sensing and tactically positioned thermocouples to yield the instantaneous evolution of i) surface temperature changes induced by carbon dioxide sequestration, ii) heat fluxes exchanged between the reacting mineral layer and its surroundings, and iii) intrinsic carbonation rates. Comparison with the adiabatic temperature rise of the surface temperature variations measured through infrared thermography highlighted significant differences in normalizing the specific heat generation rate of carbonation with respect to the carbonating mineral or to the entire hosting solid matrix. The impact of ambient atmosphere reservoir was considerable with sizable heat fluxes pumped out of the reacting material to an extent to impede temperature rises from neighbouring their theoretical adiabatic temperature analogs. This prospective study on model brucite mineral portends future prospects for assessing heat generation for the sequestration of carbon dioxide using complex multi-mineral matrices such as magnesium-silicate mineral residues.