排序方式: 共有13条查询结果,搜索用时 0 毫秒
1.
The standard thermodynamic properties and Helgeson-Kirkham-Flowers (HKF) parameters for Sb(OH)3(aq) have been estimated. For this purpose, the available solubility data for senarmontite, valentinite, stibnite, and native Sb in a wide range of temperatures (15 to 450°C) and pressures (1 to 1000 bar), and thermodynamic properties of Sb oxides (senarmontite and valentinite) have been critically analyzed. Published data were complimented by results from new experiments performed by solubility and solid-state galvanic cell methods. Both experimental data and thermodynamic calculations show that the hydroxide complex Sb(OH)3(aq) is primarily responsible for hydrothermal transport of antimony, especially at temperatures above 250°C. 相似文献
2.
The mixing of gas and aqueous fluid in hydrothermal ore-forming processes is discussed with reference to gold deposits to demonstrate that this phenomenon may affect ore deposition. Data on fluid inclusions in samples from the Sukhoi Log and Olimpiadinskoe deposits in Russia are utilized to demonstrate possible implications of gas mixing with hydrothermal solution when gold ores are formed. A simplified thermodynamic model is suggested to show how interaction between aqueous saline solutions with pure carbon dioxide or carbon dioxide—methane mixture may affect gold solubility. Further studying such processes may provide interesting information for understanding the genesis of ore mineralization. 相似文献
3.
4.
Statistical analysis of collected data revealed priority factors affecting radionuclide migration in water. Considerable changes in the coefficients of correlations between the many-year values of those factors and the water export of 90Sr make it possible to identify the stages associated with a mass passage of primary 90Sr inputs into water-soluble forms. The landscape characteristics of drainage basins were used to construct regression forecast models of the export of pollutants from watersheds. 相似文献
5.
N. N. Akinfiev M. V. Voronin A. V. Zotov V. Yu. Prokof’ev 《Geochemistry International》2006,44(9):867-878
The solubility of chlorargyrite, AgClcr, was experimentally studied in NaCl solutions (0.1, 0.2, and 0.5 m) as a function of the concentration of boric acid (up to 5 m) at 70–300°C and saturated water vapor pressure. The experimental data indicated the existence of the chloroborate species
B(OH)3Cl−. The published data on the thermodynamic properties of aqueous complexes in the B-Na-Cl-O-H system were analyzed. The obtained
HKF parameters of aqueous species can be used to calculate equilibria in the system up to 350°C.
Original Russian Text ? N.N. Akinfiev, M.V. Voronin, A.V. Zotov, V.Yu. Prokof’ev, 2006, published in Geokhimiya, 2006, No.
9, pp. 937–949. 相似文献
6.
An internally consistent thermodynamic database has been compiled for the Ag-Se (?II, 0, +IV)-S (?II, +VI)-Cl-O-H system on the basis of published experimental data. This database is fit for predicting the chemical properties of species over a broad interval of temperatures (0–600°C) and pressures (1–3000 bar). The stability constant of the hydroselenide silver complexes [AgHSeaq] and [Ag(HSe) 2 ? ] has been estimated. A thermodynamic model of the effect of Se on the transport properties of Ag-bearing hydrothermal fluid has been developed. Selenium has been found to be a good precipitant even if its concentration in the fluid is five orders lower than the sulfur concentration. When the temperature falls, the role of selenium as a precipitant becomes increasingly important. It has also been shown that the effect of hydroselenide complexes on Ag behavior in natural hydrothermal fluids may be ignored. 相似文献
7.
Potentiometric measurements were performed in the Cd(NO3)2-KCl-H2O system at 25°C and 1–1000 bar using an isothermal cell with a liquid junction and equipped with a solid contact Cd-selective
electrode. At 1 bar, the stepwise equilibrium constant of the fourth cadmium chloride complex CdCl42− has been determined (log K40 = −0.88 ± 0.25). The pressure-dependent stability constants for all cadmium chloride complexes have been experimentally established
for the first time. As pressure increases from 1 to 1000 bar, the stability constants for the first, third, and fourth complexes
change by less than 0.05 logarithmic units, whereas that for the second complex decreases by 0.33 logarithmic units. On the
basis of these data, the partial molar volumes of four cadmium chloride complexes have been determined under standard state
conditions: V
0(CdCl+) = 2.20 ± 3, V
0(CdCl2 (aq)) = 42.21 ± 5, V
0(CdCl3−) = 63.47 ± 10, and V
0(CdCl42−) = 81.35 ± 15 cm3mol−1. The linear correlation between the nonsolvation contributions of molar volumes and the number of ligands corresponds to
the change in coordination from octahedral in Cd2+ and CdCl+ to tetrahedral in CdCl2 (aq), CdCl3−, and CdCl42− complexes. Using theoretical correlations, the HKF parameters allowing calculation of the volumetric properties of cadmium
chloride complexes in a wide range of temperature and pressure have been obtained. The pressure effect on cadmium concentration
in sphalerite in equilibrium with the H2O-NaCl hydrothermal fluid has been estimated. It is shown that the Cd content in sphalerite increases with pressure. 相似文献
8.
A new, virial-like equation of state (EoS) for describing the thermodynamic properties of aqueous nonelectrolytes at infinite dilution is proposed. It is based on the accurate EoS for a solvent (H2O) given by Hill (1990) and requires only three empirical parameters to be fitted to experimental data, and these are independent of temperature and pressure. Knowledge of the thermodynamic properties of a pure gas, together with these three parameters, enables prediction of the whole set thermodynamic properties of the solute at infinite dilution (chemical potential, entropy, molar volume, and apparent molar heat capacity) over a wide range of temperatures (0 to 500°C) and pressures (1 to 2000 bars), including the near-critical region. In the cases in which experimental thermodynamic data are lacking, the empirical parameters can be estimated solely from the known standard-state properties of the solute. The new EoS is compatible with the Helgeson-Kirkham-Flowers model for aqueous electrolytes, and thus it can be applied to reactions involving minerals, gases, and aqueous ions, in addition to uncharged species. 相似文献
9.
V. Yu. Prokof’ev L. D. Zorina V. A. Kovalenker N. N. Akinfiev I. A. Baksheev A. N. Krasnov G. A. Yurgenson N. V. Trubkin 《Geology of Ore Deposits》2007,49(1):31-68
The mineral composition of the Talatui gold deposit has been studied with modern methods. Previously unknown minerals (ilmenite, siegenite, glaucodot, wittichenite, matildite, hessite, pilsenite, zircon, tremolite, cummingtonite, hercynite, and goethite) have been identified in the ore. A high Re content has been detected in molybdenite. The spatiotemporal separation of Au and Ag is caused by different mineral species of these elements and their diachronous precipitation during the ore-forming process. Gold crystallized along with early mineral assemblages, beginning from virtually pure gold (the fineness is 996). Silver precipitated largely at the end of the process as hessite (Ag2Te) and matildite (AgBiS2). The temperature of ore deposition varied from 610 to 145°C, the pressure was 3370–110 bar, and the salt concentration ranged from 56.3 to 0.4 wt % NaCl equiv. The heterogeneous state (boiling) of fluid at the early stages has been documented. The chemical and isotopic compositions of the fluid testify to its magmatic nature and the participation of meteoric water at late stages in the ore-forming process. Thermodynamic modeling reproduces the main specific features of ore formation, including separation of Au and Ag. A physicochemical model of the gold mineralization in the Darasun ore district has been proposed. On the basis of several attributes, the Talatui deposit has been referred to the prophyry gold-copper economic type. 相似文献
10.
Nikolay N. Akinfiev 《Geochimica et cosmochimica acta》2009,73(6):1597-1608
Knowledge of the solubility of quartz over a broad spectrum of aqueous fluid compositions and T-P conditions is essential to our understanding of water-rock interaction in the Earth’s crust. We propose an equation to compute the molality of aqueous silica, mSiO2(aq), mol·(kg H2O)−1, in equilibrium with quartz and water-salt-CO2 fluids, as follows: