Calcium carbonate, analysis calcite

X-ray diffraction analysis of the products of the benefici-ation of Dow-Colony shale is shown in Table I. It is clear that the oleophilic extract (pellets) retains or concentrates the calcium and magnesium carbonates (dolomite, calcite, aragonite), particularly the dolomite. The hydrophilic gangue consists mainly of feldspar and quartz. Since silica, silicates and Ca/Ca-Mg carbonates, in a clean condition, are water wettable... 

Klaproth found that precipitated alumina is soluble in caustic potash(i789). He proved by analysis that anhydrite (then called muriacite) is calcium sulphate free from water and that calcite and aragonite are two different crystalline forms of calcium carbonate and confirmed that bitter spar (dolomite) is a compound of calcium and magnesium carbonates. 

X-ray diffraction analysis of the films showed calcite, vaterite, and a broad amorphous region due to the organic material and/or amorphous calcium carbonate. 

The potential for well-bore scale during these CO2 treatments is determined by first predicting how much carbonate mineral dissolution will take place. After a calcite saturation index has been calculated for a water analysis for both pre- and post-C02 treatment, then Fig. 7 can be used to determine how much calcium (and therefore bicarbonate) will have been added to treated waters from calcite dissolution. These calcium and bicarbonate values can be added to the original formation water, which is then used to calculate a new calcite saturation index for the new water. 

The system associates a quality variable q x with each parameter, x, of the analysis. Each quality variable is assigned an initial value of zero. When there is evidence to support or contradict the reliability of the parameter value, the quality variable is incremented or decremented. Consider the calcium concentration in an analysis. Initially its quality variable, q calcium, is set to zero. Assume that the carbonate species concentrations have been shown to be reliable but that the geochemical model shows calcite to be oversaturated by several tenths of a unit. The sample is of a limestone ground water, and so should be calcite saturated. Assuming that the program and thermochemical data used are correct, the calcite oversaturation can be interpreted as indicating an erroneous calcium analysis. q calcium is therefore decremented because of this evidence that the calcium value is incorrect. The overall quality... 

Next, low-temperature (<150°C), low-pressure torr) oxygen plasmas oxidized organic components of the sample to CO2. Decomposition of inorganic carbon present (dolomitic limestone rock and calcite/calcium oxalate accretions) was prevented by running the plasmas at low-temperature. Carbon dioxide from the sample was flame-sealed into a glass tube cooled to liquid nitrogen temperature (-194°C), after water had been frozen out with a dry-ice/ethanol slurry (-58°C), and finally sent for radiocarbon analysis at the Center for Accelerator Mass Spectrometry at the Lawrence Livermore National Laboratory (LLNL-CAMS). It was necessary to utilize an AMS measurement due to the small sample size. 

In all the tests, some calcite and/or portlandite had precipitated (identified by XRD, morphology and chemical analysis). Some precipitation of portlandite was expected to occur on heating because its solubility decreases with increasing temperature. The additional presence of calcite in nearly all the products, despite attempts to limit the ingress of CO2, shows how readily calcium hydroxide becomes carbonated. 

Mineralogical analysis of the carbon skeldons of about 50 species from New Zealand showed that they were formed of mixtiues of calcite and aragonite, in which the proportion of caldte ranged from 0% to 100%, with a mean value of 85%. The rate of replacement of calcium by magnesium in calcite varies among species from 0% to 11% (Smith, Nelson, and Spencer, 1998). 

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