Abstract
The transformation of CO2 into a precipitated mineral carbonate through an ex situ mineral carbonation route is considered a promising option for CO2 capture and storage (CCS) since (i) the captured CO2 can be stored permanently, and (ii) industrial wastes (i.e. coal fly ash, steel and stainless-steel slags, and cement and lime kiln dusts) can be recycled and converted into value-added carbonate materials by controlling polymorphs and properties of the mineral carbonates. The final products produced by the ex situ mineral carbonation route can be divided into two categories − low-end high-volume and high-end low-volume mineral carbonates− in terms of their market needs as well as their properties (i.e. purity). Therefore, it is expected that this can partially offset the total cost of the CCS processes. Polymorphs and physicochemical properties of CaCO3 strongly rely on the synthesis variables such as temperature, pH of the solution, reaction time, ion concentration and ratio, stirring, and the concentration of additives. Various efforts to control and fabricate polymorphs of CaCO3 have been made to date. In this review, we present a summary of current knowledge and recent investigations entailing mechanistic studies on the formation of the precipitated CaCO3 and the influences of the synthesis factors on the polymorphs.
Highlights
It is generally recognized that global warming is caused by the accumulation of greenhouse gases in the atmosphere, including CO2 in particular
Unlike in situ mineral carbonation, ex situ mineral carbonation carries out a series of chemical processes above ground via reactions between CO2 and alkaline earth metals such as calcium or magnesium that are extracted from naturally occurring silicate minerals, i.e., wollastonite, olivine, serpentine, etc., or industrial by-products or waste materials, i.e., coal fly ash, steel and stainless-steel slags, and cement and lime kiln dusts (Gerdemann et al, 2007)
As opposed to in situ methods, this technique allows the utilization of alkaline-metal feedstock extracted from industrial wastes, which are generally recognized to have environmentally hazardous effects, and in this light providing an appropriate method for proper disposal or for recycling is a significant environmental issue
Summary
It is generally recognized that global warming is caused by the accumulation of greenhouse gases in the atmosphere, including CO2 in particular. Unlike in situ mineral carbonation, ex situ mineral carbonation carries out a series of chemical processes above ground via reactions between CO2 and alkaline earth metals such as calcium or magnesium that are extracted from naturally occurring silicate minerals, i.e., wollastonite, olivine, serpentine, etc., or industrial by-products or waste materials, i.e., coal fly ash, steel and stainless-steel slags, and cement and lime kiln dusts (Gerdemann et al, 2007) Because this technology involves energy-intensive processes during the preparation of the solid reactants, including mining, transport, grinding and/or activation, as well as the recycling of additives and catalysts, process optimization is required for cost reduction (IPCC, 2005; Oelkers et al, 2008). We present a summary of current knowledge and recent investigations involving mechanistic studies on the formation of the precipitated CaCO3 and the influences of the synthesis factors on the polymorphs
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call