An experimental study of gypsum dissolution coupled to CaCO3 precipitation and its application to carbon storage (original) (raw)
Related papers
2011
Steady state calcite precipitation rates were measured in mixed-flow reactors at 25 °C and pH ~9 in the presence and absence of aqueous sulphate. Two aqueous inlet solutions were used to provoke precipitation 1) containing NaHCO 3 and Na 2 CO 3 and 2) a second containing CaCl 2. 0-20 mM of Na 2 SO 4 was added to this second solution to assess the effects of the presence of aqueous sulphate on rates. The presence of aqueous sulphur is found to decrease calcite precipiation rates; the presence of 20 mM lowers calcite dissolution rates by a factor of 2 at a constant Ω of 2.6. The slowing of calcite precipitation may aid subsurface carbon storage efforts as it will slow pore clogging of injected rock formation. In addition as the rate limiting step of mineral carbonation is the dissolution of divalent-metal bearing silicate solids such as basaltic glass or olivine, it seems likely that a decrease of carbonate precipitation rates of a factor of 2 will negligibily effect mineral carbonation efforts.
2011
Steady state calcite precipitation rates were measured in mixed-flow reactors at 25 °C and pH ~9 in the presence and absence of aqueous sulphate. Two aqueous inlet solutions were used to provoke precipitation 1) containing NaHCO 3 and Na 2 CO 3 and 2) a second containing CaCl 2. 0-20 mM of Na 2 SO 4 was added to this second solution to assess the effects of the presence of aqueous sulphate on rates. The presence of aqueous sulphur is found to decrease calcite precipiation rates; the presence of 20 mM lowers calcite dissolution rates by a factor of 2 at a constant Ω of 2.6. The slowing of calcite precipitation may aid subsurface carbon storage efforts as it will slow pore clogging of injected rock formation. In addition as the rate limiting step of mineral carbonation is the dissolution of divalent-metal bearing silicate solids such as basaltic glass or olivine, it seems likely that a decrease of carbonate precipitation rates of a factor of 2 will negligibily effect mineral carbonation efforts.
Carbonate geochemistry and its role in geologic carbon storage
2021
Massive quantities of CO 2 need to be captured and stored to address the potential consequences of global warming. Geologic storage of CO 2 may be the only realistic option available to store the bulk of this CO 2 due to the required storage volumes. Geologic storage involves the injection of CO 2 into the subsurface. This injection will lead to the acidification of the formation fluids and provoke a large number of fluid-mineral reactions in the subsurface. Of these reactions, those among CO 2-rich fluids and carbonate minerals may be the most significant as these reactions are relatively rapid and have the potential to alter the integrity of caprocks and well bore cements. This review provides a detailed summary of field, laboratory and modeling results illuminating the potential impacts of the injection of large quantities of CO 2 into the subsurface as part of geologic storage efforts
Carbon dioxide sequestration by ex-situ mineral carbonation
2000
The process developed for carbon dioxide sequestration utilizes a slurry of water mixed with olivine-forsterite end member (Mg 2 SiO 4), which is reacted with supercritical CO 2 to produce magnesite (MgCO 3). Carbon dioxide is dissolved in water, to form carbonic acid, which likely dissociates to H + and HCO 3-. The H + hydrolyzes the silicate mineral, freeing the cation (Mg 2+), which reacts with the HCO 3 to form the solid carbonate. Results of the baseline tests, conducted on ground products of the natural mineral, have demonstrated that the kinetics of the reaction are slow at ambient temperature (22LC) and subcritical CO 2 pressures (below 7.4 MPa). However, at elevated temperature and pressure, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant conversion to the carbonate occurs. Extent of reaction is roughly 90% within 24 hours, at 185LC and partial pressure of CO 2 (P CO2) of 11.6 MPa. Current studies suggest that reaction kinetics can be improved by pretreatment of the mineral, catalysis of the reaction, and/or solution modification. Subsequent tests are intended to examine these options, as well as other mineral groups.
Energy & Fuels, 2009
Capturing carbon dioxide is vital for the future of climate-friendly combustion, gasification, and steam-reforming processes. Dry processes utilizing simple sorbents have great potential in this regard. Long-term calcination/carbonation cycling was carried out in an atmospheric-pressure thermogravimetric reactor. Although dolomite gave better capture than limestone for a limited number of cycles, the advantage declined over many cycles. Under some circumstances, decreasing the carbonation temperature increased the rate of reaction because of the interaction between equilibrium and kinetic factors. Limestone and dolomite, after being pretreated thermally at high temperatures (1000 or 1100°C), showed a substantial increase in calcium utilization over many calcination/carbonation cycles. Lengthening the pretreatment interval resulted in greater improvement. However, attrition was significantly greater for the pretreated sorbents. Greatly extending the duration of carbonation during one cycle was found to be capable of restoring the CO 2 capture ability of sorbents to their original behavior, offering a possible means of countering the long-term degradation of calcium sorbents for dry capture of carbon dioxide. † University of British Columbia. ‡ Natural Resources Canada.
Calcite precipitation by a high-pressure CO2 carbonation route
The Journal of Supercritical Fluids, 2006
The formation of powdered calcite from slurries containing a calcium source and carbon dioxide (industrial carbonation route) is a complex process of considerable importance nowadays. In the absence of additives, the rhombohedral morphology can be obtained in precipitation processes by using solution routes, but rarely by the industrial method where the most common morphology of precipitated calcite is the scalenohedral one. In this work, the conditions and mechanisms for producing calcite particles with various shapes and sizes have been investigated in a reaction between aqueous calcium hydroxide and compressed carbon dioxide (compressed vapour, liquid or supercritical). Influence of pressure, temperature and reaction time were analyzed. Rhombohedral calcite with a very low degree of agglomeration was obtained under supercritical conditions. The carbonation process was also applied to the in situ precipitation of calcite inside of the pores of cellulose paper. (C. Domingo).
Carbonate Precipitation in Engineered Environments; Carbon Sequestration by Design
2010
Summary Calcite precipitation in urban and other disturbed soils takes place as a natural consequence of the weathering of artificial calcium silicate minerals and glasses. In studies of such soils in the UK, twice as much carbonate C has been observed in urban soils as is held within rural soils as organic C. This process takes place by carbonation of soil minerals derived from demolition or waste disposal. Estimates of the overall capacity of soils to accommodate C in this way are of the order of 100-1000 MT annually, which is comparable to other carbon capture technologies. This passive sequestration of C requires very low energy inputs, and can be designed into land remediation and other engineering works.
Geochimica et Cosmochimica Acta, 1996
Dissolution of CaCO3 in the system H2OCO2CaCO3 is controlled by three rate-determining processes: The kinetics of dissolution at the mineral surface, mass transport by diffusion, and the slow kinetics of the reaction H2O + CO2 = H+ + HCO3−. A theoretical model of Buhmann and Dreybrodt (1985a, b) predicts that the dissolution rates depend critically on the ratio VA of the volume V of the solution and the surface area A of the reacting mineral. Experimental data verifying these predictions for stagnant solutions have been already obtained in the range 0.01 cm < VA < 0.1 cm. We have performed measurements of dissolution rates in a porous medium of sized CaCO3 particles for VA in the range of 2·10−4 cm and 0.01 cm in a system closed with respect to CO2 using solutions pre-equilibrated with an initial partial pressure of CO2 of 1·10−2 and 5·10−2 atm. The results are in satisfactory agreement with the theoretical predictions and show that especially for VA < 10−3cm dissolution is controlled entirely by conversion of CO2 into H+ and HCO3−, whereas in the range from 10−3 cm up to 10−1 cm both CO2-conversion and molecular diffusion are the rate controlling processes. This is corroborated by performing dissolution experiments using 0.6 μmolar solutions of carbonic anhydrase, an enzyme enhancing the CO2-conversion rates by several orders of magnitude. In these experiments CO2 conversion is no longer rate limiting and consequently the dissolution rates of CaCO3 increase significantly. We have also performed batch experiments at various initial pressures of CO2 by stirring sized calcite particles in a solution with VA = 0.6 cm and VA = 0.038 cm. These data also clearly show the influence of CO2-conversion on the dissolution rates. In all experiments inhibition of dissolution occurs close to equilibrium. Therefore, the theoretical predictions are valid for concentrations c ≤ 0.9 ceq. Summarising we find good agreement between experimental and theoretically predicted dissolution rates. Therefore, the theoretical model can be used with confidence to find reliable dissolution rates from the chemical composition of a solution for a wide field of geological applications.