ИСТИНА

В ходе работ по проекту планируется расширить область экспериментальной изученности гидротермальных систем на «нетрадиционные» параметры температура-давление-состав. Все опыты будут выполнены методом растворимости в разных его модификациях. Первая задача - надёжно установить схему комплексообразования Au в присутствии серы в промежуточных степенях окисления, включая радикалы серы S3- и S2-. Растворимость Pd и PdS(к) будет определена в диапазоне температур 25 – 450°С при давлении до 1000 бар с определением констант устойчивости хлоридных и сульфидных комплексов. Концентрация растворённых солей будет варьировать вплоть до насыщенных по NaCl флюидов. Вторая задача – создать базу экспериментальных данных для термодинамического описания распределения рудных металлов между жидкой и паровой фазами, и получить данные по составу и устойчивости комплексов металлов в малоплотном флюиде (паре). Новые экспериментальные данные будут согласованы с полученными нами ранее в более простых системах и литературными данными (включая результаты опытов при температуре 900-1000°С). Будут определены параметры моделей Хелгесон-Киркхэм-Флауэрс (HKF, плотность флюида > 0.35 г*см-3) и Акинфиев-Даймонд (AD, флюиды от малоплотных до плотных). Кроме того, планируется разработать подход для описания распределения металлов (на примере Au, Cu, Zn) между жидкой и паровой фазой. Таким образом, результаты экспериментов, термодинамическая обработка полученных данных и развитие термодинамических методов описания гидротермальных систем позволят рассчитывать растворимость важнейших металлов в рудоносных флюидах в более широком, чем это доступно в настоящем, диапазоне физико-химических параметров и составов, максимально приближая «модельные» системы к реальным природным.

The transport of ore metals by hydrothermal fluids occurs in a wide range of physicochemical parameters (temperature, pressure/density, redox potential) and concentrations of dissolved chlorides. However, the main experimental works on the study of hydrothermal complex formation were carried out at temperatures up to 500°С in the “average” density range of 0.4–1 g*cm–3, chloride concentrations generally do not exceed 10–15 wt.%. For systems containing sulfur, the key works are performed in the area of S-2 predominance (reducing conditions). Recently, new idea has appeared on the predominant role of Au and Pt complexes, which include sulfur “radicals” S3- and S2-, in the hydrothermal transport of these metals. However, the quality of these models is doubtful, and the scheme of complex formation in such “oxidized sulfide” fluids (S-2 and S+4 or S+6 coexist) needs additional study. In addition to homogeneous fluids, an important role in the processes of ore formation is played by heterogeneous, or "boiling" hydrothermal systems, in which liquid and vapor phases coexist. The behavior of ore metals in such “non-traditional” systems for laboratory research has been poorly studied, and their thermodynamic description is currently implemented only qualitatively. In the course of work on the project, it is planned to expand the area of the experimental study of hydrothermal systems to "non-traditional" temperature-pressure-composition parameters. All experiments will be performed by the solubility method in its various modifications. The first part of the work will be performed using the classical autoclave technique with the analysis of the dissolved metal after the experiment has been quenched. The solubility of Au will be studied in "oxidized sulfide" fluids at 350 and 450°C, 500 and 1000 bar with the analysis of the dissolved metal after the test has been quenched. The aim of this series is to reliably establish the scheme of Au complexation in the presence of sulfur in intermediate oxidation states, including the S3- and S2- sulfur radicals. The solubility of Pd and PdS(c) will be determined in the temperature range of 25 - 450°C at pressures up to 1000 bar with the determination of the stability constants of chloride and sulfide complexes. The concentration of dissolved salts will vary up to NaCl-saturated fluids. To control the data obtained, a separate series of Pd dissolution experiments will be performed at 450°C/500 bar using an autoclave with internal in situ sampling and measurement of the hydrogen content (pressure) after the experiment. The solubility method with separate sampling of the liquid and vapor phases will be used to study the solubility of chalcocite Cu2S(c), metallic Au and sphalerite ZnS in coexisting liquid and vapor. Two series of experiments will be performed. The first series - in the H2O - H2S system at 300 - 350°C and saturated vapor pressure. The second series is in the H2O – H2S – NaCl system at 450°C depending on the pressure, from 500 bar (homogeneous fluid) to 250 bar (liquid-vapor equilibrium). The objectives of these series of experiments are to create a base of experimental data for the thermodynamic description of the distribution of ore metals between the liquid and vapor phases, and to obtain data on the composition and stability of metal complexes in low-density fluid (steam). The new experimental data will be regressed together with those obtained by us earlier in simpler systems and literature data (including the results of experiments at a temperature of 900-1000°C). The parameters of the Helgeson- Kirkham-Flowers (HKF, solution/fluid density > 0.35 gcm-3) and Akinfiev-Diamond (AD, low to high density fluids) models will be determined. In addition, it is planned to develop an approach to describe the distribution of metals (by the example of