Mineral trapping

Xu T., Apps J.A., et al Reactive geochemical transport simulation to study mineral trapping for C02 disposal in deep arenaceous formations. 2003 Journal of Geophysical Research 108(B2) 2071-2084. 

Mito S., Xue Z., et al. Mineral trapping of C02 at Nagaoka test site. In Proceedings of Eighth International Conference on Greenhouse Gas Control Technologies, Trondheim, Norway. 2006. 

Mineral trapping is the fixing of C02 in carbonate minerals as a result of geochemical reactions among aquifer brines, formation minerals, and aqueous species of C02. The density of C02 in... 

The mineral trapping takes place in three steps as demonstrated by the example of anorthite dissolution ... 

Reactions with alkali feldspars do not provide divalent cations for the precipitation of carbonate minerals and initially were thought to be of little significance for mineral trapping (Gunter et al. 1997). However, more recent work indicates that dissolution of alkali feldspars contributes to the fixing of C02 as the sodium alumino-carbonate mineral dawsonite, NaAlC03(0H)2 (Johnson et al. 2001). In this case, the Na necessary for dawsonite precipitation is available in abundance in the brine, but dissolution of alkali feldspar provides a source of aluminum and neutralizes the acidic C02 according to (Johnson et al. 2001) ... 

The feasibility of mineral trapping of C02 in dawsonite is demonstrated by the Bowen-Gunnedah-Sydney Basin in Australia, which has abundant diagenetic dawsonite that formed in response to magmatic C02 (Baker et al. 1995). In addition, abundant dawsonite in the... 

Dissolution of carbonate minerals does not lead to mineral trapping of C02 (Gunter et al. 1993). However, carbonate dissolution, and other mineral precipitation-dissolution reactions can impact sequestration capacity by altering the permeability of the aquifer near the injection site. 

Results from equilibrium modelling indicate that the extent of mineral trapping depends strongly on the fugacity of C02. Consequently, the extent of mineral trapping is sensitive to the rate of mineral-brine-C02 reactions relative to the rate of flow and dispersion of C02 away from the site of injection. Reactions must be fast enough to reach carbonate phase saturation before the C02 is overly diluted by outward radial flow, dispersion, and diffusion. The rates of reaction and the factors that influence the rates of reaction must be better constrained. 

Bachu, S., Gunter, W. D. Perkins, E. H. 1994. Aquifer disposal of C02 hydrodynamic and mineral trapping. Energy Conversion and Management, 35, 269-279. 

Hitchon, B. (ed) 1996. Aquifer Disposal of Carbon Dioxide Hydrodynamics and Mineral Trapping -Proof of Concept. Geoscience Publishing Ltd., Alberta, Canada. 

Experimental investigations of carbon dioxide mineral trapping have been started, but there is little understanding of the processes involved on the molecular level, due to the complex nature of the brine and the physical conditions present in the brine aquifers. One such complexity issue is the dissolution of CO2 from the gaseous phase into aqueous solution. This process is thermodynamically unfavorable with a ArG° value of 2.00 kcal/mol, in pure water at STP [3]. This becomes even more thermodynamically unfavorable as salts are introduced into the solution. Figure 17.1 shows how the solubility of CO2 in aqueous solution is also dependent upon the salt concentration and salt composition, even from simple salt solutions. According to Fig. 17.1, there is no correlation with size and the ability for the solution to uptake the C02. 

Basalts are also widely distributed in nature. Commonly, they have low porosity, low permeability and low pore space continuity. These properties do not bode well for gas storage. Nonetheless, basalt may have some potential for the permanent mineral trapping of carbon dioxide, because the gas may react with silicates in the matrix to form carbonate minerals. This requires further investigation. 

Thus, through this mineral trapping, CO2 can be trapped almost permanently underground. 

Geochemical modeling methods have been used to estimate the amount of CO2 that can be stored in an aquifer by solubility and mineral trapping. Most of the geochemical modeling simulations have been conducted based on the following equation (e.g., Perkins and Gunter 1995 Talman et al. 2000)... 

The reaction rate constants ka, k , kb ) are the most important parameters affecting solubility and mineral trapping. Consequently, numerous experiments have been conducted to examine the reaction rates (dissolution) for different rock types (granite, volcanic rocks (basalt etc.), sedimentary rocks etc.) and minerals as a function of pH, temperature etc. (e.g., Shikazono et al. 2012 Adachi and Shikazono 2009 Umemura et al. 2014a, b). 

A glass composite panel with fire-retardant resin and wood core was developed for a coal mine Safe Room system as a rescue chamber for miners trapped underground [29]. In addition to using fire-retardant resins and intumescent mats integrated into the structural composite reinforcements, the coal mine Safe Room system will be coated with intumescent latex, a thin passive fire barrier to further enhance its fire-rating capacity. 

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