Экспериментально изучено влияние серы на сорбцию платины углеродистым веществом (УВ) при 200–400°C и Робщ = 1 кбар. По результатам ИК-спектроскопии продуктов опытов зафиксировано ускоряющее влияние серы на конденсацию и ароматизацию УВ, при этом эффект серы на содержание Pt в органических фракциях заключен в пределах неопределенности анализа. На электронном сканирующем микроскопе (СЭМ) наблюдается образование многослойной пористой углеродной пленки на стенках ампул и платиновых подложках, непосредственно контактирующих с УВ. Состав пленки в зависимости от ее толщины (3–25 мкм) варьирует в пределах (мас. %): С = 61.06–100, Pt = 0–33.7, O = 0–5.17, S = 0–0.74. Пленка содержит включения микрокристаллов Pt, морфология которых меняется с увеличением длительности опытов от нано-микро-сфероидальной до субизометричной, таблитчатой и проволоковидной. В зависимости от размеров состав кристаллов варьирует (мас. %): Pt – 23.30–52.45, C – 49.57–73.52, O – 0–4.20. В керогене по данным СЭМ также обнаружены микрокристаллические выделения углеродистой платины, аналогичные по морфологии и составу присутствующим на пленке. Углеродистость микрокристаллов осажденной из раствора платины может быть следствием как фонового влияния субстрата пленки и керогена, так и кристаллизации их из платиноорганических комплексов. В кинетических опытах вследствие локальных электрохимических реакций образуются скопления наносфероидов (60–250 нм) вокруг более крупных микросфероидов (до 10 мкм), агрегация которых ведет к укрупнению и дальнейшей трансформации кристаллов. Сделан вывод о том, что полиморфизм, иерархическая агрегация и переменность составов платиновых образований характерны для углеродсодержащих систем вследствие их кристаллизации из платиноорганических метастабильных комплексов.

The effect of sulfur on platinum adsorption on carbonaceous matter (CM) was experimentally studied at 200–400°C and P tot = 1 kbar. The IR spectra of the experimental products indicate that sulfur accelerates HC condensation and aromatization, but the effect of sulfur on platinum concentrations in the organic fractions is within the analytical uncertainties. SEM images show the development of a multilayer porous carbonaceous film on the walls of the ampoules and platinum in physical contact with carbonaceous matter. The composition of the film varies, depending on its thickness (3–25 μm), within the following limits: 61.06–100 wt % C, 0–33.7 wt % Pt, 0–5.17 wt % O, and 0–0.74 wt % S. The film contains tiny Pt crystals, whose morphology varies with increasing duration of the experiments from nanometer- and micrometer-sized spheroids to subequant, tabular, and wire-like. Depending on their size, the composition of the crystals varies as follows: 23.30–52.45 wt % Pt, 49.57–73.52 wt % C, and 0–4.20 wt % O. According to our SEM data, the kerogen also contains tiny crystalline segregations of carbon aceous platinum whose morphology and composition are analogous to those on the film. The presence of carbon in the tiny platinum crystals deposited from solution can be explained by the background effect of the kerogen of the film and/or by their crystallization from organo-platinum complexes. In our kinetic experiments, local electrochemical reactions produced aggregates of nanometer-sized (60–250 nm) spheroids around larger micrometer-sized (up to 10 μm) spheroids, whose aggregation resulted in larger crystals and their further transformation. The polymorphism, hierarchical aggregation, and compositional variability of the platinum segregations are likely typical of car- bon-bearing systems because of their crystallization from metastable organo-platinum complexes.

The effect of sulfur on the sorption of gold by carbonaceous matter (CM) was investigated under hydrothermal conditions (200–400°C and 1 kbar) using the autoclave-ampoule method. The model CM was represented by asphaltenes fractionated from the lignite of the Pavlovskoe coal field. The source of gold was the walls of the Au container, which were dissolved in water under the experimental conditions. Sulfur was added as finely ground pyrite (C-S-Fe-O-H-Au system) or elemental sulfur powder (C-S-O-H-Au system). The contents of Au were measured by atomic absorption spectrometry with electrothermal atomization in quenched aqueous solutions (WF), soluble organic fraction (SF), and insoluble residue (kerogen). The lowest Au concentration was detected in the WF, −8.96 < logmAu < −6.32. The Au concentration is higher in the SF (−5.02 < logmAu < −4.34) and increases by more then an order of magnitude in the kerogen, −3.94 < logmAu < −2.33. The IR spectra of the experimental products showed that sulfur was accumulated in the kerogen, whereas no C-S functional groups were observed in the SF. This is the reason for the negligible influence of sulfur in this system on Au concentration in the SF. The maximum Au concentration was detected in the kerogen in the presence of pyrite, which was transformed into pyrrhotite at 400°C. Thus, iron sulfides promote Au uptake by kerogen from ore-bearing hydrothermal fluids.

The mineral and chemical composition of the carbon-bearing rocks of the Late Permian Pionerskaya Formation containing the Degdekan gold deposit has been studied. The bulk contents of Au, Ag, Pt, and Pd in the black shales and their light, sulfide, and electromagnetic fractions were determined by electrothermal atomization. The mineral composition and the phase analysis of the rocks were studied using a scanning electron microscope. Gold is present as fine xenomorphic grains of high fineness with an Fe admixture of up to 4 at %, as well as intergrowths of kustelite and electrum. The Au and Pt contents in the black shales and ores vary in a wide range (g/t): Au 0.01–13.12, Pt 0.001–1.34. The highest Au contents (up to 1748 g/t) were noted in the sulfide fraction. The Pt-bearing phases were not found, whereas a Pt content of about 0.61 wt % was determined using an electron microscope in a carbonaceous matrix. The initial rocks have a steady and low Pt content (less than 0.007 g/t). A stable even Au distribution in the studied rocks was established within 1.14–2.46 g/t. The chemical analysis of the soluble fraction of the carbonaceous matter extracted from the black shales showed the presence of Au 0.375, Ag 3.68, Pt 0.147, and Pd 0.052 g/t. It has been concluded that the carbon-bearing rocks of the Pionerskaya Formation play a resource role in the accumulation of noble metals, whereas economic concentrations of the latters are formed in the course of the superimposed metamorphic-hydrothermal processes.