Carbonate mineral matrix

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

Fricke M, Volkmer D (2007) Crystallization of Calcium Carbonate Beneath Insoluble Mono-layers Suitable Models of Mineral-Matrix Interactions in Biomineralization 270 1-41 Fujimoto D, see Tamura R (2007) 269 53-82... 

The kerogenic material present in the Green River shale which is of Eocene Age is bound to a mineral matrix composed of carbonates, quartz, clays, and other minor minerals. The isolation of this organic material can, therefore, be carried out in two ways. 

Scanning electron micrographs (SEM) of bioleached shale, which has been leached with the acid produced by sulfur-oxidizing bacteria, have revealed a pitted, spongy-appearing surface texture. Bioleaching removes primarily the carbonate minerals, such as dolomite and calcite, which are apparently deposited in pits throughout the rest of the mineral matrix. The removal of the carbonate would be expected to increase the porosity of the raw shale. Since the results of SEM reveal only the surface... 

Y-intercept and the slope, respectively, and are listed in Table I. The results of the dissolution rate determination method (method 2) are presented in Figure 3. As can be seen, the maximum removable mineral (P0) by dilute acid is independent of the size of the shale particles. However, the carbonate fraction in the shale mineral matrix is very close to this figure. This could mean that the accessibility of the leaching agent to the leachable materials in shale is complete in the size ranges studied in this experiment—but at different rates. This could also indicate that the carbonate deposit sites are not isolated but can, perhaps, be thought of as interconnected by minerals built of the dilute acid-resistant minerals. 

The figure 2/3 is the dimension of the specific surfaces such as the case of the sublimation rate of mothball in the air. However, the presence of non-carbonate minerals and organic structures (kerogen matrix) which separate the carbonate mineral into isolated sites connected by channels would alter the rate so that ... 

The inorganic component of bone is primarily platelike (20 to 80 nm long and 2 to 5 nm thick) crystalhne hydroxyapatite, Ca5(P04)3(0H) or HA (Kaplan et al., 1994 Park and Lakes, 1992). Small amounts of impurities may be present in the mineralized HA matrix for example, carbonate may replace phosphate groups, whereas chloride and fluoride may replace hydroxyl groups. Because release of ions from the mineral bone matrix controls cell-mediated functions, the presence of impurities may impact important biological aspects (and, subsequently, affect chemical and mechanical properties of bone) that are critical to normal bone function for example, impurities present in the mineralized matrix may affect cellular function(s) that influence new bone formation (Kaplan et al., 1994 Park and Lakes, 1992). 

The zeolite-carbon adsorbents from mineral-carbon adsorbents group are novel and exhibit not quite well recognized properties with their unique, modified porous structure. The characteristic structures for zeolite, active carbon and intermediate structure exist in these materials. Such a structure results fi-om the modification of a surface of a mineral matrix by depositing carbon material. The efifectivity of enrichment of the structure of zeolite-carbon adsorbents (in relation to crystalline zeolite structure) in hydrophobic micropores (0.4 - 2 nm) and macropores (above 50 nm) is proportional to the fi action of carbon phase. Such combination of hydrophilic properties of mineral phase and hydrophobic properties of organic phase results in various sorptive properties of the material and the range of their application can be consequently extended. Additionally, the chemical resistance of these adsorbents for their exploitation in aggressive conditions takes place. 

Figure 2 The fate of phosphorus during soil formation can be viewed as the progressive dissolution of primary mineral phosphorus (dominantly apatite), some of which is lost from the system by leaching (decrease in Ptotai). and some of which is reincorporated into nonoccluded, occluded, and organic fractions within the soil. Nonoccluded phosphorus is defined as phosphate sorbed to surfaces of hydrous oxides of iron and aluminum, and calcium carbonate. Occluded phosphorus refers to phosphorus present within the mineral matrix of discrete mineral phases. The initial buildup in organic phosphorus results from organic matter return to soil from vegetation supported by the soil. The subsequent decline...

World annual production of natural diamonds, the cubic form of carbon, is about 110 million carats (1 carat = 200 mg). Almost all is derived from kimberlite or its weathered remnants, but Australian production is from the Argyle mine, at which the host rock is lamproite. Kimberlites are olivine- and volatUe-rich potassic ultrabasic rocks of variable geological age that typically form near-vertical carrot-shaped pipes intmded into Archean cratons. The volatile-rich component is predominantly CO2 in the carbonate minerals calcite and dolomite, and the texture is characteristically inequigranular, with large grains (macrocrysts), usually of olivine [Mg2Si04], in a fine-grained, olivine-rich matrix. 

The HC1 extraction preferentially separated carbonate minerals from the remaining mineral matter matrix. As Table III indicates for the 184 L/t oil shale, approximately 99% of the Ca and approximately 96% of the Mg were removed as expected. The bitumen- and carbonate-free fraction is also found to contain about 28% less A1 which is probably associated with other mineral matter (e.g., albite and analcime) partially soluble in HC1. (The rather large decrease in the Fe concentration from 3.7 wt% in the benzene/methanol treated oil shale to 1.2 wt% for the HC1 treated shale is due to mechanical magnetic separation discussed in the experimental section and dissolution by HC1 of minerals such as ankerite and siderite.) The HC1 extraction resulted in a weight loss of 28.6 wt%. It is determined that at least 0.45 and 0.38 wt% of the total organics in the 104 and 184 L/t dried oil shale, respectively, are recoverable in the HCl/ether extracts and, thus, are intimately associated with carbonate minerals. In addition, the results of the second benzene/ methanol Soxhlet extraction indicate that 3.40 and 3.65 wt% of the total organics which are bitumen in these two samples are released when the carbonate minerals are removed from the shale. 

In this study, an extraction approach to the problem of attractive interactions in Green River (Mahogany Zone) oil shale resulted in the preferential dissolution of both carbonate and silicate minerals. As the results in Table IV indicate, the interfacial organic layer between kerogen and the inorganic mineral matrix was also simultaneously separated. Since the majority of the bitumen was removed in the initial benzene/... 

The process of carbon deposit formation in complex carbon-mineral adsorbents may be initiated and terminated in any stage or stages of scheme 1. This is dependent on the chemical nature of the carbonized substance, porous structure and chemical nature of adsorption and catalytic sites of the mineral matrix, etc. For this reason, the complex adsorbents prepared by the third and fourth methods have the carbon deposits consisting of the substances of different chemical and physical structure formed during the defined stages of Scheme 1. 

---