Kaolinite chemical analysis

Fig. 6.3. Saturation indices of Amazon River water with respect to various minerals (left) calculated directly from a chemical analysis, and (right) computed assuming that equilibrium with kaolinite and hematite controls the fluid s aluminum and iron content.

Kaolinite seldom occurs interstratified with 2 1 clay minerals although Sudo and Hayashi (1956) described a randomly interstratified kaolinite-montmorillonite in acid clay deposits in Japan. On the basis of the chemical analysis (Si02 = 41.94, A1203 = 30.12, Fe203 = 2.42, FeO = 0 21, MgO = 1.52, CaO = 0.32, Ti02 = 0.40, H20+ =... 

The group named Minerals, which occurs as discrete particles principally of quartz, kaolinite and pyrite/marcasite is expressed in terms of chemical analysis as -... 

Assuming that goethite and kaolinite are finite solids, enter the chemical analysis into M1NTEQA2, except for the Fe and A1 concentrations. Compare computed ZFe(lII)(aq) and ZAl(aq) concentrations at saturation with goethite and kaolinite to the values in the table. How much Fe and A1 may be in suspension Next assume that the water is in equilibrium with goethite and montmorillonite (make them finite solids). Now what is the computed ZAl(aq) concentration ... 

An ultimate chemical analysis alone does not give all the necessary information. For instance, if an analyst reports that a clay has a silica content of 60%, we do not know whether this silica is present as free silica , quartz, or combined as kaolinite or as mica. If, however, we can find out precisely what minerals are in the clay, it may be possible to calculate the percentages of each mineral from the chemical analysis and this calculation provides the so-called rational analysis of the clay. 

In each of the different parageneses outlined here, the instability of a mineral can be denoted by its replacement with one or usually several minerals. The rocks in these facies are typified by multi-phase assemblages which can be placed in the K-Na-Al-Si system. This is typical of systems where the major chemical components are inert and where their masses determine the phases formed. The assumptions made in the analysis up to this point have been that all phases are stable under the variation of intensive variables of the system. This means that at constant P-T the minerals are stable over the range of pH s encountered in the various environments. This is probably true for most sedimentary basins, deep-sea deposits and buried sedimentary sequences. The assemblage albite-potassium feldspar-mixed layered-illite montmorillonite and albite-mixed layered illite montmorillonite-kaolinite represent the end of zeolite facies as found in carbonates and sedimentary rocks (Bates and Strahl,... 

Beckett described inductively coupled plasma mass spectrometry (ICP-MS) as an off-line detector for FFF which could be applied to collected fractions [ 149]. This detector is so sensitive that even trace elements can be detected making it very useful for the analysis of environmental samples where the particle size distribution can be determined together with the amount of different ele-ments/pollutants, etc. in the various fractions. In case of copolymers, ICP-MS detection coupled to Th-FFF was suggested to yield the ratio of the different monomers as a function of the molar mass. In several works, the ICP-MS detector was coupled on-line to FFF [150,151]. This on-line coupling proved very useful for detecting changes in the chemical composition of mixtures, in the described case of the clay minerals kaolinite and illite as natural suspended colloidal matter. 

Energy dispersive X-ray analysis (EDXA) is of assistance in identifying the principal chemical elements in particular crystals. This information, along with crystal shape, enables one to identify reasonably well the minerals likely to be contacted by a surfactant slug when injected into a core or a reservoir formation. Thus, the basic sand matrix of these materials is revealed while the presence of particular clay minerals, such as kaolinite, can be seen in Berea sandstone and Glenn Sand dolomite appears to be present in significant amounts in the core from the San Andres formation. 

Chemical characterization of fines implies the elemental and mineral compositional analysis of migratory fines in porous media. Khilar and Fogler (1998) presented the range in chemical composition of migratory clays primarily of kaolinite, illite, montmorillonite, and chlorite particles in Table 5.6. We observe from this table that silica, Si02, and alumina are the major minerals. 

The distinction between kaolinite and halloysite can be difficult. Even when techniques of X-ray diffraction, differential thermal analysis, electron microscopy, and chemical treatments are combined, the result may still be doubtful. If hydrated halloysite is present, it can be detected by a basal spacing of 7.3 A or larger, which shifts to smaller spacings when the sample... 

If much well-ordered kaolinite is present, the assymmetric peaks are not prominent in the patterns from random samples, and the basal reflections are sharper and much enhanced in intensities in patterns from oriented samples. If much disordered kaolinite is present, the assymmetric peaks are prominent in the first patterns, and the basal reflections are much enhanced in the second. Chemical pretreatments prior to X-ray diffraction, such as those proposed by Wada [1965] and Alexiades and Jackson [1965], are sometimes useful in determining amounts of kaolinite and halloysite. Where the halloysite is tubular, it is easily detected in electron micrographs, although the amount can seldom be determined. Amounts of hydrated halloysite can be determined if allophane is not present in differential thermal analysis by calibrating and measuring the low-temperature endothermic peak. 

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