Calcite, 856 table

Solid phases that precipitate at —20 °C include ice, mirabilite, and calcite (Table A.2). In this particular case, we used the equilibrium crystallization option as a consequence, the columns labeled Moles and Accumulated moles are identical. Had we used fractional crystallization, then the Moles column would have contained the moles of the solid phase that precipitated in the last temperature/evaporation/pressure step, and the Accumulated moles would include the total precipitation of that solid phase over all steps. 

Site 14 in X Cave, which was tentatively classed as a vadose flow on the basis of its mean discharge greater than 10 m /s, is probably more related to the vadose seepages despite its variable discharge (only slightly more variable than site 8, see Table I) and low (which probably represents nearly complete ventilation in the cave environment prior to sampling). Its correlation between Ca and soil co, (as discussed earlier), the wide variation in CO2 relative to Ca (Fig. 4), and its supersaturation with respect to calcite (Table I) makes it resemble the vadose seepages more than the flows. 

The difference between total crystal energy per formula unit (computed for the optimized equilibrium structure) and energies of isolated atoms gives 5(HF), the Hartree-Fock approximation to the binding energy of magnesite and calcite (Table 8). The atomic energies were calculated with... 

Siderite, strontianite and magnesite are also calculated to be close to saturation (Table 6). However, these results reflect the fact that the various metal carbonates were simulated as discrete phases, rather than as calcite-dominated solid solutions. The rather high contents of Fe, Mg and Sr found in calcite from fracture fillings supports the hypothesis that the siderite, strontianite and magnesite actually occur in solid solution with calcite (Table 2). 

Carbonate Decomposition. The carbonate content of Green River oil shale is high (see Table 4). In addition, the northern portion of the Piceance Creek basin contains significant quantities of the carbonate minerals nahcoUte and dawsonite. The decomposition of these minerals is endothermic and occurs at ca 600—750°C for dolomite, 600—900°C for calcite, 350—400°C for dawsonite, and 100—120°C for nahcohte. Kinetics of these reactions have been studied (19). Carbon dioxide, a product of decomposition, dilutes the off-gases produced from retorting processes at the above decomposition temperatures. 

The commercial grades of calcium carbonate from natural sources are either calcite, aragonite, or sedimentary chalk. In most precipitated grades aragonite is the predominant crystal stmcture. The essential properties of the two common crystal stmctures are shown in Table 1. 

A wide variety of precipitates form in cooling water systems carbonates, silicates, sulfates, and phosphates are common. Below and slightly above 212°F (100°C), calcite, aragonite, gypsum, hydroxyapatite, magnesium phosphate, anhydrite, and serpentine are commonly encountered (see Table 4.1). 

NOTE For any boiler, the maximum recommended tolerance for deposit thickness can be related to a weight of deposit per unit area clearly, the weight will vary dependent on the density of the deposit. Typically, deposit densities vary between 2.3 and 5.7 g/cm3. The densities of calcite and magnetite (which are two common mineral components of deposits) are 2.71 and 5.17 g/cm3, respectively. Table 4.2 assumes an average deposit density of 3.5 g/cm3. 

The precipitation of CaCOj in the absence of any additives was carried out under the same nucleation condition (run 1 in Table 1). The crystal phase of the obtained CaCOj was a mixture of calcite and vaterite by IR. The vaterite content... 

The precipitations of CaCOj in the presence of the Cl.5, G3.5, and G4.5 PAMAM dendrimers were carried out with constant -COONa unit and calcium ions of 0.1 mol/1. Although vaterite was predominantly formed by the G4.5 dendrimer, relatively high amount of calcite was observed in the case of the G3.5 and G1.5 dendrimers (Table 2). These results suggest that the G4.5 dendrimer effec-... 

The Okuaizu geothermal system is characterized by high temperatures (maximum 340°C), high salinity (about 2 wt% total dissolved solids (TDS)) and large amounts of non-condensable gases (1 wt% CO2 and 200 ppm H2S). The pH of the hydrothermal solution measured at 25°C is 6.44 (Table 2.6). However, the pH of the original fluid in the reservoir is computed to be 4.05. This pH as well as alkali and alkali earth element concentrations are plotted near the equilibrium curve of albite, K-mica, anhydrite and calcite (Fig. 2.19) (Seki, 1991). 

Szabo BJ, Kolesar PT, Riggs AC, Winograd H, Lndwig KR (1994) Paleochmatic iirferences from a 120,000-year calcite record of water-table fluctuations in Browns Room of Devils Hole, Nevada. Qnat Res 41 59-69... 

Homopolymers. Polymers such as poly(methacrylamido-4,4,8,8-tetra-methyl-4,8-diaza-6-hydroxynonamethylene dichloride), abbreviated poly(MDTHD), and a triaza analog, abbreviated poly(MTHHDT), have been shown to be effective stabilizers of silica, calcite, and hematite (14,15) as indicated by the data summarized in Table V. 

Copolymers of MDTHD and DMAPMA appeared to be the most effective silica, calcite, and hematite mineral fines stabilizers. Increasing the copolymer MDTHD content had little effect on polymer performance. Similar results were observed for a series of MDTHD -DMAEMA copolymers and a series of DMAEMA CH-C1 salt - DMAEMA copolymers (Table VI). In contrast, increasing the MDTHD content of MDTHD - NNDMAm copolymers from 67% to 90% improved copolymer performance as a silica fines and hematite fines stabilizer. 

Limited silica fines stabilization data indicated that increasing copolymer molecular weight from 100,000 to 1,000,000 daltons had, if anything, a negative effect on silica fines stabilization. At a molecular weight of 1,000,000 daltons, this copolymer appeared to be more effective in stabilizing silica fines than silica/kaolinite, calcite, or hematite fines. However, the results may be due in part to the larger particle size and lower surface area of the silica fines (see Table II). 

Trace elements can be adsorbed on the surface of calcite, influencing their solubility in calcareous soils of arid and semi-arid zones. The carbonate bound fraction is the major solid-phase component for many trace elements (Cd, Pb, Zn, Ni and Cu) in arid and semi-arid soils, especially in newly contaminated soils (Table 5.3). In Israeli arid soils treated with metal nitrates, the carbonate bound fraction is the largest solid-phase component (60-80%, 50-60%, 40-60%, 30-40%, and 25-36% for Cd, Pb, Zn, Ni, and Cu respectively). Divalent metallic cations at low aqueous concentrations first associate with calcite via adsorption reactions. Then they may be incorporated into the calcite lattice as a co-precipitate by recrystallization (Franklin and Morse, 1983 Komicker et al., 1985 Davis et al., 1987 Zachara et al., 1988 Reeder and Prosky, 1986 Pingitore and... 

Once the pure mineral powders characterized, 3 mixtures were manually prepared and named ML1, ML2 and ML3. They contain each of the 8 minerals in different proportions reproducing 3 mine tailings falling in the uncertainty zone of the static test used. The 3 synthetic tailings were characterized with the same techniques as for the pure minerals. Cp and Sp weight fractions were evaluated from their chemical element tracers (respectively Cu and Zn) obtained from ICP-AES analysis. Qz, Dol, and Sid samples are considered pure and their percentages in the mixtures are not corrected. Table 1 presents the fraction of each mineral in the three mixtures before and after correction taking into consideration the contamination of Po sample by pyrite and calcite, as previously determined. The corrected mineral proportions are used for calculation of the static test parameters based on... 

A number of studies have been conducted [1,2] in which different fatty acid modifications were examined. High selectivity and high calcite-dolomite recoveries were obtained with emulsified fatty acid with soda ash and sodium silicate. Table 22.2 shows the results from calcite/dolomite flotation using different fatty acid type collectors and various modifications. 

The reagent scheme developed for the White Mountain titanium ore is shown in Table 25.15. Gangue depressants H2SiF6, oxalic acid and DAX1 were used. Depressant DAX2 is a mixture of low-molecular-weight acrylic acids designed specifically to depress calcite. 

Table A. 8.1 Equilibrium Constants for Carbonate and CaC03 (calcite) Equilibria ...

Figure 1. Compilation of 5 Mg values (relative to DSM3) for various terresttial and exb aterresttial reservoirs. Data and sources are tabulated in Table 1. For the carbonates, die black points represent dolomite while the open symbols represent calcite.

Figure 7. A Mg vs. 5 Mg plot of calcite speleothems and their drip waters from the Soreq cave site, Israel (data from Galy et al. 2002) compared with seawater. The horizontal trend of the data suggests that Mg in carbonates is related to aqueous Mg by equilibrium fractionation processes. Results of a three-isotope regression, shown on the figure and in Table 3, confirm that the (3 value defined by the data is similar to the predicted equilibrium value of 0.521 and distinct from kinetic values. The positive A Mg characteristic of the speleothem carbonates is apparently inherited from the waters. The positive A Mg values of the waters appear to be produced by kinetic fractionation relative to primitive terrestrial Mg reservoirs (the origin).

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