Dissolution of carbonates

The dissolution of carbonates can create spectacular features like those found in many caves. The process is termed karstification. Some reservoirs are related to Karst. Examples are the Bohai Bay Field in China or the Nang Nuan oil field in the Gulf of Thailand. These reservoirs are characterised by high initial production from the large open pore system. However, since the Karst features are connected downdip to the waterleg this is usually followed by rapid and substantial water breakthrough. ... 

The dissolution of carbon in molten iron in the lower part of the furnace, leads to the reduction of manganese oxide (eq. 15) and some sihea (eq. 14), both in the slag, whereby the subsequent dissolution of these metals occurs in the molten iron. 

Neutralizing Amines. Neutralizing amines are used to neutralize the acid (H" ) generated by the dissolution of carbon dioxide or other acidic process contaminants in the condensate. These amines hydrolyze when added to water and generate the hydroxide ions required for neutralization ... 

A new, low-pressure, plasma-assisted proeess for synthesising diamonds has been found by Roy et al [83,84]. An intimate mixture of various forms of carbon with one of many metals (e.g., Au, Ag, Fe, Cu, Ni) is exposed to a microwave plasma derived from pure hydrogen at temperatures ranging from 600-1000 °C. Roy et al postulate a mechanism in which a solid solution of atomic hydrogen and the metal. Me, facilitates dissolution of carbon to form molten droplets of Me -Cj,-H. Diamonds nucleate at the surface of the droplets as the temperature is reduced. 

The dissolution of carbonates by acid is an undesired result of acid rain, which has damaged the appearance of many historic marble and limestone monuments (Fig. 11.19 marble and limestone are forms of calcium carbonate). 

Francois R, Bacon MP, Suman DO (1990) Thorium 230 profiling in deep-sea sediments high resolntion records of flux and dissolution of carbonate in the equatorial Atlantic during the last 24,000 years. Paleoceanography 5(5) 761-787... 

The presentation finally descends on the very last of the listed chemical precipitation processes, and this pertains to precipitation implemented by carbonate anions (CO-). The dissolution of carbon dioxide takes place with the formation of the weak diabasic acid, H2C03. The overall dissociation of this acid (dissociation constant, KD) is represented by ... 

Both of these facts are employed in the carbonation process of sodas and beer and some sparkling wines. Low-temperature conditions and CO2 pressures of 3 to 4 atm are used to enhance the dissolution of carbon dioxide gas in water. The graph in Fig. 3.1.1 presents the solubility of carbon dioxide in water at various temperatures and pressures. The parameter used to express CO2 solubility is... 

Dissolution of carbonate by NaOAc-HOAc solutions at varying pHs from arid-zone soils, as indicated by X-ray diffraction, are presented in Fig. 4.1. Arid soils from Israel contained varying contents of CaC03 (from 13.7-68.1%). X-ray diffraction showed that calcareous soils used in this study... 

Dissolution of carbonated sediments is, probably unduly (Broecker and Peng, 1982), neglected. 

The rate of chemical weathering is related to the rate of C02 consumption. Consider first the dissolution of carbonates... 

Dissolution of carbonates can only occur if the solution is thermodynamically undersaturated, pH is an important variable affecting the saturation ratio (Appendix 8.1 gives a brief review of the CaC03 solubility characteristics in open and closed systems). 

Wollast, R. (1990), "Rate and Mechanism of Dissolution of Carbonates in the System CaC03-MgC03", in W. Stumm, Ed., Aquatic Chemical Kinetics, Reaction Rates of Processes in Natural Waters, Wiley-Interscience, New York, pp. 431-445. 

Chou, L, R.M. Garrels, and R. Wollast (1989), "Comparative study of the kinetics and mechanisms of dissolution of carbonate minerals", Chemical Geology 78, 269-282. 

The speciation of polyprotic acids is complicated by the occurrence of multiple hydrolyses. For example, the dissolution of carbonic acid involves the following equilibria ... 

Carbon dioxide has a dominant effect on the dissolution of carbonate minerals, such as calcite and dolomite (Table 2.1). If a carbonate mineral dissolves in water that is equilibrated with a constant source of CO, then the concentration of dissolved carbonic acid remains constant and high. However, when calcite dissolution is accompanied by consumption of carbonic acid and a continuous source of CO is not maintained, the reaction proceeds further to achieve equilibrium. 

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. 

Ion exchange reactions between cations present in groundwater and in the interlayer space of the montmorillonite structure. These are mainly the replacement of 2Na+ by Ca2+ and Mg2+ present in ground-waters. This triggers the dissolution of carbonates according to equilibria like the one exemplified by equation (1). The ion-exchange reactions can be described by ... 

Another explanation would be that dissolution of carbonates created an alkaline environment according to the reaction below. 

Rate of Dissolution of Carbonate Mineral Matrix in Oil Shale by Dilute Acids... 

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