2 research outputs found
Optimization of mineral carbonation process for CO2 sequestration by lime-rich coal ashes
Mineral carbonation is one of the alternatives considered for CO2 sequestration. This consists of inducing
the artificial weathering of alkaline minerals to produce stable carbonate solids. This work presents the
wet carbonation of lime-rich ashes from the fluidized bed combustion of two different fuels: a Spanish
sulfur-rich lignite, with calcium carbonate and quartz as main mineral constituents, and the waste produced
during the extraction of the coal. The novelty of the work is its experimental approach, which
explores all the variables (pH, temperature, time, liquid to solid ratio, NaCl ratio) from a statistical survey
centered on finding optimized conditions that maximize the degree of carbonation. CO2 uptake is determined
by direct thermogravimetric tests. The results indicate that high carbonation efficiency (78% efficiency)
is achieved for both solids at basic pH and moderate treatment times. Those conditions cause
anhydrite to dissolve, increasing the availability of Ca2+ for reprecipitation as carbonate and hydroxide.
At neutral pH, 72% conversion efficiency is equivalent to a capture of 8% of the CO2 theoretically emitted
in the combustion of coal wastes. The proposed conditions for fly ash carbonation enables rapid CO2 capture
that is applicable for upscaling and industrial use.The authors would like to express their gratitude to the
Government of Aragon and La Caixa for their financial support of
the work through the project DGA-LC-025/2010, and to CarbonÃferas
del Ebro for supplying the fuels used in this work. M.P. Gimeno
acknowledges support from the Spanish National Research Council
(CSIC) through their JAE-Doc program.Peer reviewe