Home – Home – Jornals – Advanced Search

The Myauchan ore field located in the Omsukchan zone of the Okhotsk-Chukotka Volcanic Belt is described. The Korennoe and Malyutka Ag-Pb-Zn ore occurrences forming this field are localized at the center of anticlinal fold of NW strike made up of Upper Triassic carbonate-terrigenous deposits intruded by stock-like bodies and dikes of Upper Cretaceous andesite, monzodiorite, granite-porphyry, and rhyolite-porphyry. Sulfide-carbonate-fluorite-quartz veins and vein-veinlet zones with arsenopyrite, pyrite, sphalerite, galena, chalcopyrite, and Ag-tetrahedrite are localized both in intrusions and in terrigenous strata. The field bears As-Sb-Ag-Pb-Au-Bi-Cu-Zn-W mineralization. Study of fluid inclusions and REE and ore element patterns show that the field ores formed from chloride solutions with the participation of surface waters in hydrothermal-magmatic system under epithermal conditions. The ores were deposited from solutions with TDS = 0.5-9.0 wt.% NaCl equiv. in the temperature range 106-287 ºC. The ores containing ca. 70 ppm Ag and up to 1.2% Pb formed through boiling-off of solutions enriched in iron salts. The ores with Ag < 7 ppm and Pb ≤ 25 ppm were generated from diluted hydrothermal solutions with predominant sodium salts and potassium admixture. Mineralization of the Myauchan ore field marks the upper level of the Ag-Pb-Zn ore system similar to the Gol’tsovoe deposit.

The chemical composition and reactivity of the native cellulose of cotton grass ( Eriophorum scheuchzeri ) in the production of cellulose nitroesters based on this type of raw material are investigated to assess the suitability of the native cellulose fibres of the seed pods ( Eriophorum scheuchzeri ) for the production of cellulose nitroesters on this basis. It is shown that the mass fraction of cellulose in the studied plant raw materials reaches 79 %. The degree of cellulose polymerization is 1510 units. The possibility of obtaining cellulose nitroesters in a practical yield of 64 % on the basis of this type of plant raw materials without preliminary delignifying treatment has been revealed. The chemical composition of the obtained cellulose nitroesters has been established. Their technical compliance with colloxylin H is shown. Based on the conducted studies, an intermediate conclusion is made about the potential suitability of this type of plant raw materials for the production of cellulose nitroesters.

The phase compositions and particle morphology of nanostructured Co-Pt system, obtained by the reduction of aqueous solutions of precursors with hydrazine hydrate, have been studied (for the first time in the Pt-rich region) by X-ray diffraction analysis (XRD), transmission electron microscopy (coupled with electron diffraction (ED)), thermogravimetry, small-angle X-ray scattering analysis (SAXS) and elemental analysis of the samples. As determined by XRD, with Co content less than approximately 60 at%, the only phase is determined: the face-centred cubic ( fcc ) phase of the solid solution of Co in Pt, with the upper limit of Co solubility in Pt equal to 18±1 at%. For Co content in the solid solution higher than its solubility limit during the synthesis, diffraction-undetectable phase (phases) is also formed in addition to the fcc solid solution phase. The presence of such phases was confirmed by the results of SAXS, and their metal nature, rather than oxide-hydroxide one, was confirmed by XRD, ED, and thermal analysis.

The catalytic reaction of n-heptane (n-C₇H₁₆) oxidation with molecular oxygen has been studied. Various compositions of the polymer catalyst Mn-P4VP/MBAA (where Mn-P4VP is manganese-immobilised poly-4-vinylpyridine and MBAA is N,N′-methylene-bis-acrylamide) containing 2-5 wt% Mn were prepared and tested. The concentration of manganese in the catalyst based on immobilized metal-polymer complexes is within the range of 2-5 wt% Mn. The oxidation reaction was carried out at a ratio of components n-C₇H₁₆/O₂/polymer catalyst with Mn = 1 : 3.38 : 0.003 and time 6 h within the temperature range 303-383 K. The data on the yield of the major products of n-heptane oxidation are presented, taking into account the initial components, catalyst composition, temperature and the time of oxygen contact with the reacting components. It has been established that during the oxidation of _n-C₇H₁₆ (303-383 K), the yield of alcohols is higher than the yield of other oxidation products. The oxidative conversion of _n-heptane increases from 45 to 75 mol% with an increase in temperature in the range of 303-383 K. For the multistage oxidation of n-heptane with oxygen, a kinetic model was selected and considered. On the basis of this model, the reaction rate constants were calculated in the range of 303-383 K considering the degree of heptane conversion. The activation energy of n-heptane oxidation was estimated, taking into account the method of choosing the most plausible parameter and experimental data on n-heptane convection.

One of the main problems in oil production is the formation of stable oil-water emulsions that cause corrosion of pipelines, malfunction of pumping equipment, and poisoning of catalysts at refineries. The features of the viscosity-temperature behaviour of high-viscosity resinous crude oil from the Russkoye field (Yamal-Nenets autonomous district) and its 30 wt% emulsion after exposure to electromagnetic and low-frequency acoustic fields are investigated. Electromagnetic treatment of crude oil leads to a decrease in the phase transition temperature and the yield strength coefficient. Low-frequency acoustic processing of the emulsion is accompanied by a decrease in the effective viscosity and the yield strength coefficient. After a complex wave action, the viscosity-temperature characteristics of crude oil continue to fall, and the stability of the formed emulsions decreases due to the intense coalescence of water-phase droplets. It is shown that the amount of released asphaltenes in oil-containing systems decreases after wave treatment. On the contrary, after a complex impact, their content in crude oil increases, while in the emulsion it continues to decrease. This is likely to occur due to the release of hydrocarbons occluded in the asphaltene structure into the liquid oil phase.

Chemical modification of phenyl-formaldehyde oligomers (PFO) was carried out, and compositions based on elastomer, co-oligomer and bitumen were developed in order to achieve significant improvement of characteristics and expand the areas of PFO application. The phenol-formaldehyde oligomer was modified with carbamide by co-polycondensation in an alkaline medium. The basic physicochemical, physical-mechanical and performance characteristics of the co-oligomer were studied. The co-oligomer of the new composition, obtained at the first stage of the investigation, was used as a binder. At the second stage of investigation, a three-component composition was developed on the basis of elastomer, co-oligomer and bitumen, and a composite material was prepared. This material was shown to exhibit good protective properties, and it may be recommended to provide anti-corrosive protection of the equipment and installations in oil and gas mining industry. The effect of the amounts of introduced components on the major characteristics of the resulting composition was studied. It is shown that the introduction of a nitrogen-containing modifier (carbamide) into PFO causes a decrease in the content of free phenol and formaldehyde, which is important both from the environmental viewpoint and in relation to the hazardous action of these components on the human organism.

The kinetics and mechanism of hydrogen evolution on the MoSi₂ electrode in x M H₂SO₄ + (0.5-x ) M Na₂SO₄ ( x = 0.50; 0.35; 0.20) solutions have been studied. The cathodic polarization curves of MoSi₂ in the studied solutions are characterized by Tafel region with a slope of (-0.070)±0.002 V. The reaction order of the cathodic process with respect to hydrogen ions at the potentials of Tafel region is ~1.0; the derivative of the electrode potential with a change in electrolyte acidity is ~0.072 V. The impedance spectra of the MoSi₂ electrode in the studied potential range have the shape of a semicircle located in the capacitive half-plane, with the centre in the region of positive values of the imaginary impedance component; in the region of the highest frequencies, a short straight section is recorded on the impedance plots, indicating the presence of pores in the surface layer of the electrode. To describe the hydrogen evolution reaction on MoSi₂, we used an equivalent electrical circuit, the Faraday impedance of which consists of series-connected charge transfer resistance ( R₁) and a parallel R₂C₂Z_d-chain responsible for the adsorption of atomic hydrogen on the surface and its diffusion into the depth of the electrode material. The equivalent circuit also includes the solution resistance (R_s) and the double layer capacitance impedance, which is modeled by the constant phase element CPE₁. It is shown that the hydrogen evolution reaction on molybdenum disilicide in a sulphuric acid electrolyte proceeds along the discharge - recombination route with a quasi-equilibrium discharge stage when the Temkin logarithmic isotherm for adsorbed atomic hydrogen is fulfilled. The hydrogen evolution reaction is complicated by hydrogen absorption proceeding in the mode of solid-phase diffusion kinetics.

Physicochemical foundations for the technology of nitrogen acid processing of serpentinite from the Karakalpak deposit with the formation of pure magnesium nitrate and magnesium-containing compound fertiliser are developed. The chemical and mineralogical composition of serpentinite from the Karakalpak deposit is studied. As determined by X-ray diffraction analysis, microscopic and thermogravimetric studies, serpentinite sample contains clinoenstatite, pyrope, spinel, magnetites and other minerals with various crystal structures. Data on the extraction of serpentinite components in nitric acid by decomposition under different conditions (temperature, duration, nitric acid concentration) are presented. The subsequent stages of nitric acid extract processing have been carried out: removal of silica residue, ammonisation of the filtrate in order to precipitate undesirable impurities to obtain magnesium nitrate. The process of evaporation and crystallization of the filtrate to obtain pure magnesium nitrate has been studied.

The content of the main groups of biologically active substances in the flowers, leaves, rhizomes of Iris setosa cultivated under the conditions of the forest-steppe zone of the Novosibirsk Region has been determined. The content of tannins, pectins, protopectins, catechins, flavonoids, carotenoids during the seasonal development of plants was determined. It is found that tannin content in the leaves in all phenophases of I. setosa plant development is 6.3-8.5 times higher than in rhizomes. During the flowering period, flavonoid content in the leaves is 29.7 times higher than in rhizomes, during the stage of blossom fading it is 18.1 times higher, and at the stage of fruiting it is 25.1 times higher. The same accumulation of catechins (0.23-0.24 wt%) was found in underground and aboveground organs during the period of blossom fading. Pectin content in leaves during fruiting was detected to be 2.4-2.7 times higher than during flowering and blossom fading. Pectin content in rhizomes is 2.2-2.4 times higher during blossom fading and fruiting than during flowering. The content of carotenoids in flowers during flowering is 2 times higher than in rhizomes, but 2.6 times lower than in leaves. It is noted that the quantitative content of biologically active substances in the organs of I. setosa is determined by the peculiarities of growth and development during the seasonal period.

Pilot-scale tests results and laboratory studies of fire-resistant hydraulic fluid based on the developed hydraulic concentrate Hydrotol-ITCh HFAE are presented. Stable operation and operating parameters preservation of the developed hydraulic fluid physicochemical properties under the real conditions on a contaminated hydraulic system of a mining industry enterprise are shown. It was found that during six months of operation, the range of pH values, electrical conductivity, concentration and bacteriological purity did not change significantly, while the concentrate refilling, as well as the use of special disinfectants and cleansers, was not required. For the first time, the microbial composition of hydraulic fluid exposed to operation in the powered supports of the enterprise was studied using the method of metagenomic sequencing. Molecular genetic methods revealed a wide range of bacterial associates with various types of metabolism, including anaerobic sulphate-reducing bacteria involved in the biological corrosion of metals.