Leaching kinetics of sulfides from refractory gold concentrates by nitric acid

The processing of refractory gold-containing concentrates by hydrometallurgical methods is becoming increasingly important due to the depletion of rich and easily extracted mineral resources, as well as due to the need to reduce harmful emissions from metallurgy, especially given the high content of arsenic in the ores. This paper describes the investigation of the kinetics of HNO3 leaching of sulfide gold-containing concentrates of the Yenisei ridge (Yakutia, Russia). The effect of temperature (70–85 °C), the initial concentration of HNO3 (10–40%) and the content of sulfur in the concentrate (8.22–22.44%) on the iron recovery into the solution was studied. It has been shown that increasing the content of S in the concentrate from 8.22 to 22.44% leads to an average of 45% increase in the iron recovery across the entire range temperatures and concentrations of HNO3 per one hour of leaching. The leaching kinetics of the studied types of concentrates correlates well with the new shrinking core model, which indicates that the reaction is regulated by interfacial diffusion and diffusion through the product layer. Elemental S is found on the surface of the solid leach residue, as confirmed by XRD and SEM/EDS analysis. The apparent activation energy is 60.276 kJ/mol. The semi-empirical expression describing the reaction rate under the studied conditions can be written as follows: 1/3ln(1 - X) + [(1 - X)-1/3 - 1] = 87.811(HNO3)0.837(S)2.948e-60276/RT·t. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The research was funded by the Russian Science Foundation, grant number 18-19-00186. The SEM/EDS and microprobe analysis were funded by State Assignment, grant number 11.4797.2017/8.9

Nitric Acid Dissolution of Tennantite, Chalcopyrite and Sphalerite in the Presence of Fe (III) Ions and FeS2

This paper describes the nitric acid dissolution process of natural minerals such as ten-nantite, chalcopyrite and sphalerite, with the addition of Fe (III) ions and FeS2. These minerals are typical for the ores of the Ural deposits. The effect of temperature, nitric acid concentration, time, additions of Fe (III) ions and FeS2 was studied. The highest dissolution degree of sulfide minerals (more than 90%) was observed at a nitric acid concentration of 6 mol/dm3, an experiment time of 60 min, a temperature of 80 °C, a concentration of Fe (III) ions of 16.5 g/dm3, and an addition of FeS2 to the total mass minerals at 1.2:1 ratio. The most significant factors in the break-down of minerals were the nitric acid concentration, the concentration of Fe (III) ions and the amount of FeS2. Simultaneous addition of Fe (III) ions and FeS2 had the greatest effect on the leaching process. It was also estab-lished that FeS2 can be an alternative catalytic surface for copper sulfide minerals during nitric acid leaching. This helps to reduce the influence of the passivation layer of elemental sulfur due to the galvanic linkage formed between the minerals, which was confirmed by SEM-EDX. © 2022 by the author. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 075-03-2021-051/5, 20-79-00317, FEUZ-2021-0017Funding: This work was funded by the Russian Science Foundation Project No. 20-79-00317. The SEM-EDX, XRF, XRD analysis were funded by State Assignment, grant No. 075-03-2021-051/5 (FEUZ-2021-0017)

Myth in the structure of national consciousness

In the context of globalization processes, the problem of nations and national selfconsciousness has become one of the most widely discussed in the modern social sciences and humanities. Within the framework of globalization approaches, a nation is viewed as a transitional formation between traditional locality and planetary interdependence. According to modern theories, the model of a nation is built on the basis of Western European developmental patterns. From such viewpoint, the characterization of ethnicity is rejected, as a feature of “primitive”, “pre-political” societies as marginal groups doomed to assimilation into the existing structures. The central problem of ethnical belonging is the issue of origin, the restoration of cultural and historical memory and the construction of the “appropriate past”, which would assist in solving the problems of the present. The core of any national culture is national-ethnic self-consciousness which is the key factor in the national identity formation. It is pointed out that certain types of myths are inseparable from the ethnic identity. Today, researchers speak of the process of “remythologization”. For Russia, which has always been a multiethnic state, the problem of scientific definition of nations, ethnic groups, national and ethnic consciousness has a special practical significance. In Russia and the post-Soviet space, the activation of mythological thinking has its own specifics.Keywords: Nations, Ethnicity, National consciousness, Myth, Globalizatio

Исследование реакционной способности производных коричной кислоты – предшественников лигнина

Objectives. Cinnamic acid derivatives belong to a large class of phenolic compounds, which are widely distributed in plants and have high potential for use in the medical and industrial fields. They have various useful practical properties, e.g., antioxidant, anti-inflammatory, antiplatelet, and anti-melanogenic properties. Hydroxycinnamic acids are of particular interest as phenylpropanoids, which are the starting compounds of lignin. The aim of this work was to study the electronic structure and analyze the reactivity of the simplest representatives of phenylpropanoids formed during the biosynthesis of the coumaric (p-hydroxycinnamic), caffeic (3,4-dihydroxycinnamic), ferulic (3-methoxy-4-hydroxycinnamic), sinapic (3,5-dimethoxy-4- hydroxycinnamic), and 3,4-dimethoxycinnamic acids. These acids are the biogenetic precursors of most other phenolic compounds (coumarins, melanins, lignins, and flavonoids) and are found in almost all higher plants.Methods. Calculations with full optimization of the geometric parameters were performed using the original Hartree–Fock theory and hybrid density functional method. All calculations were performed using the Firefly program. Results. A comparative quantum chemical calculation of the geometric parameters of hydroxycinnamic acid molecules was conducted via two methods, and the values of the charges on atoms according to Mulliken were determined. It was found that with the addition of hydroxyl and methoxy substituents at the meta and para positions relative to the carboxyl fragment, the electron density shifts toward the benzene ring, and the symmetry of the molecule decreases. Additionally, in these structures, there is π,π-conjugation of the carboxyl fragment of the –СН=СНСООН molecule with the aromatic ring, which significantly affects the geometric configuration of the molecule. The maximum positive charge is concentrated on the C9 atom, while the maximum negative charge is on the oxygen atoms belonging to the methoxy substituents and the hydroxyl group, which confirms the role of oxygen atoms in the chemical transformations of acids. Conclusions. Two different methods were used to calculate the geometric, electronic, and energy parameters and electrophilicity indices of the studied hydroxycinnamic acids in the gas phase. The obtained values were consistent (within the limits of error) with the experimental data as well as the results described in earlier works’ calculations by other methods.Цели. Производные коричной кислоты относятся к большому классу фенольных соединений, которые широко распространены в растительности и обладают высоким потенциалом для применения в медицине и промышленности. Они обладают различными практически полезными свойствами, например, антиоксидантными, противовоспалительными, антиагрегантными и антимеланогенными свойствами. Отдельный интерес представляют оксикоричные кислоты как фенилпропаноиды, являющиеся исходными соединениями лигнина. Целью данной работы является исследование электронной структуры и анализ реакционной способности простейших представителей фенилпропаноидов, образующихся в процессе биосинтеза: кумаровой (п-оксикоричной), кофейной (3,4-дигидроксикоричной), феруловой (3-метокси-4-гидроксикоричной), синаповой (3,5-диметокси-4-гидроксикоричной) и 3,4-диметоксикоричной кислот. Эти кислоты являются биогенетическими предшественниками большинства других фенольных соединений (кумаринов, меланинов, лигнина и флавоноидов) и встречаются практически во всех высших растениях. Методы. В рамках ограниченного метода Хартри Фока и метода гибридного функционала плотности оптимизированы исследуемые молекулы. Все расчеты проводились с использованием программы Firefly. Результаты. Проведен сравнительный квантово-химический расчет геометрических параметров молекул оксикоричных кислот двумя методами, приведены значения зарядов на атомах по Малликену. При введении гидроксильных и метоксильных заместителей в м- и п-положения относительно карбоксильного фрагмента происходит смещение электронной плотности в сторону бензольного кольца и, как следствие, понижение симметрии молекулы. Также в исследуемых структурах имеется π,π-сопряжение карбоксильного фрагмента молекулы –СН=СНСООН с ароматическим кольцом, что существенно сказывается на геометрической конфигурации молекул. Максимальный положительный заряд сосредоточен на атоме С9, а максимальный отрицательный – на атомах кислорода, относящихся к метоксильным заместителям и гидроксильной группе, что подтверждает роль кислородных атомов в химических превращениях кислот. Выводы. В работе двумя различными методами были рассчитаны геометрические, электронные и энергетические параметры, а также индексы электрофильности исследуемых оксикоричных кислот в газовой фазе. Полученные величины согласуются в пределах погрешностей с экспериментальными данными, а также описываемыми в ранних работах при расчетах другими методами

Deposition of arsenic from nitric acid leaching solutions of gold—arsenic sulphide concentrates

At present, the processing of refractory gold–arsenic sulphide concentrates is becoming more relevant due to the depletion of rich crude ore reserves. In the process of the nitric acid leaching of arsenic sulphide minerals, solutions are formed containing 20–30 g/L of arsenic (III). Since market demand for arsenic compounds is limited, such solutions are traditionally converted into poorly soluble compounds. This paper describes the investigation of precipitating arsenic sulphide from nitric acid leaching solutions of refractory sulphide raw materials of nonferrous metals containing iron (III) ions using sodium hydrosulphide with a molar ratio of NaHS/As = 2.4–2.6, which is typical for pure model solutions without oxidants. The work studied the effect of temperature, the pH of the solution and the consumption of NaHS and seed crystal on this process. The highest degree of precipitation of arsenic (III) sulphide (95–99%) from nitric acid leaching solutions containing iron (III) ions without seed occurs with a pH from 1.8 to 2.0 and a NaHS/As molar ratio of 2.8. The introduction of seed crystal significantly improves the precipitation of arsenic (III) sulphide. An increase in seed crystal consumption from 0 to 34 g/L in solution promotes an increase in the degree of transition of arsenic to sediment from 36.2 to 98.1% at pH = 1. According to SEM/EDS and XRF sediment data, from the results of experiments on the effect of As2S3 seed crystal consumption, acidity and molar ratio of NaHS/As on the precipitation of arsenic (III) sulphide and the Fetotal/Fe2+ ratio in the final solution, it can be concluded that the addition of a seed accelerates the crystallisation of arsenic (III) sulphide by increasing the number of crystallisation centres; as a result, the deposition rate of As2S3 becomes higher. Since the oxidation rate of sulphide ions to elemental sulphur by iron (III) ions does not change significantly, the molar ratio of NaHS/As can be reduced to 2.25 to obtain a precipitate having a lower amount of elemental sulphur and a high arsenic content similar to that precipitated from pure model solutions. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This work was financially supported by the Russian Science Foundation Project No. 20-79-00321. The SEM–EDS analyses were funded by State Assignment, Grant No. 0836-2020-0020

Pressure oxidation of arsenic (Iii) ions in the h3aso3-fe2+-cu2+-h2so4 system

The processing of low-grade polymetallic materials, such as copper–zinc, copper–lead– zinc, and poor arsenic-containing copper concentrates using hydrometallurgical methods is becom-ing increasingly important due to the depletion of rich and easily extracted mineral resources, as well as due to the need to reduce harmful emissions from metallurgy, especially given the high content of arsenic in ores. Ferric arsenates obtained through hydrothermal precipitation are the least soluble and most stable form of arsenic, which is essential for its disposal. This paper describes the investigation of the oxidation kinetics of As (III) ions to As (V) which is required for efficient puri-fication of the resulting solutions and precipitation of low-solubility ferric arsenates. The effect of temperature (160–200 °C), the initial concentration of Fe (II) (3.6–89.5 mmol/dm3), Cu (II) (6.3–62.9 of mmol/dm3) and the oxygen pressure (0.2–0.5 MPa) on the oxidation efficiency of As (III) to As (V) was studied. As (III) oxidation in H3AsO-Fe2+-Cu2+-H2SO4 and H3AsO-Fe2+-H2SO4 systems was controlled by a chemical reaction with the apparent activation energy (Ea (≈84.3–86.3 kJ/mol)). The increase in the concentration of Fe (II) ions and addition of an external catalyst (Cu (II) ions) both have a positive effect on the process. When Cu (II) ions are introduced into the solution, their catalytic effect is confirmed by a decrease in the partial orders, Fe (II) ions concentration from 0.43 to 0.20, and the oxygen pressure from 0.95 to 0.69. The revealed catalytic effect is associated with a positive effect of Cu (II) ions on the oxidation of Fe (II) to Fe (III) ions, which further participate in As (III) oxidation. The semi-empirical equations describing the reaction rate under the studied conditions are written. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This work was financially supported by the Russian Science Foundation Project No. 20‐ 79‐00321

Standardization of epiphenomenon risks by the use of identification of early symptoms of critical states of oncohematological children

In the article is reviewed increase of effectiveness and safety of treatment of children with oncohematological conditions, by the use of timely symptoms diagnostics of epiphenomenon, critical states progression, for correction of specific and symptomatic therapy. Elsewhere, for evaluating children’s condition the PEWS (Pediatric Early Warning Systems) scale is being used, but for adequate evaluation of oncohematology children’s conditions this scale was not credible enough. The track record of observation on patients at resuscitation and intensive care unit for oncohematology children (RICU OH), has educed significant criteria for modernization of the PEWS scale. Including to it presence of various hemorrhagic syndrome, statistical frequency of transfusion and hematological parameters. The result of research shown the necessity of implementing to the scale additional criteria, and using of it at clinical recommendationsВ статье рассмотрено повышение эффективности и безопасности лечения детей с онкогематологическими заболеваниями, путем своевременной диагностики предвестников риска развития осложнений, критических состоянии, для коррекции специфической и симптоматической терапии. За рубежом для оценки состояния у детей используется шкала PEWS (Pediatric Early Warning Systems), но для адекватной оценки состояния онкогематологических детей данная шкала была недостаточно достоверна. Опыт наблюдения за пациентами в отделении реанимации и интенсивной терапии для онкогематологических детей (ОРИТ ОГ), выявил значимые критерии для модернизации шкалы «PEWS». Включив в нее наличие различного геморрагического синдрома, частоту трансфузии и показатели крови. Результат исследования показал о необходимости внедрения в шкалу дополнительных критерии, и использования его в клинических рекомендация

Analysis of patients’ therapy with the superficial venous thrombosis

The results of the analysis of the treatment of patients with superficial subcutaneous venous thrombosis. The medical histories of patients that were treated in 2019 in the cardiovascular departments of two clinical hospitals of Ekaterinburg: MAI "City clinical hospital №40" PHI "Clinical hospital "Railways- Medicine". We analyzed and compared the results of various tactics for the treatment of superficial venous thrombosis (SVT): operative and conservative in 82 patients with an average age of 55.5 years. The obtained data was compared with the national recommendations for the treatment of SVT. Operative tactics were used in 69 patients (84.1% of cases), conservative – in 13 patients (15.9% of cases). 81 (98.7 %) patients were discharged from the hospital with recovery. There is 1 fatal case due to massive PE in 1 day after admission. According to the results of the control examination, complete relief of the inflammatory process was registered in most cases – 76 (93.8%), partial in 5 cases (6.2%). However, a different pattern was observed for the regression of the thrombotic process: complete recanalization was registered only in 7 (8.7%). An addition to the existing treatment strategy for HTP HAS been proposed.Представлены результаты анализа лечения пациентов с поверхностным варикотромбофлебитом. За основу были взяты истории болезни пациентов, лечившихся в 2019 году в сосудистых отделениях двухклинических больниц г. Екатеринбурга: МАУ «Городская клиническая больница №40» и ЧУЗ «Клиническая больница «РЖД-Медицина». Проанализированы и сравнены результаты различных тактик по лечению поверхностного варикотромбофлебита (ВТФ): оперативной и консервативной у 82 пациентов, средний возраст которых составил 55,5 лет Полученные данные были сравнены с национальными рекомендациями по лечению ПВТФ. Оперативная тактика была принята у 69 пациентов (84,1% случаев), консервативная – у 13 пациентов (15,9% случаев). Из стационара с выздоровлением выписан 81 (98,7 %) пациент. Имеется 1 летальный случай вследствие массивной ТЭЛА в 1 сутки после поступления. По результатам контрольного осмотра зарегистрировано полное купирование воспалительного процесса в большинстве случаев – 76 (93,8%), частичное в 5 случаях (6,2%). Однако по регрессу тромботического процесса наблюдалась другая картина: полная реканализация зарегистрирована лишь у 7 (8,7%). Предложено дополнение к существующей тактике лечения ПВТФ

PEDIA: prioritization of exome data by image analysis

Purpose Phenotype information is crucial for the interpretation of genomic variants. So far it has only been accessible for bioinformatics workflows after encoding into clinical terms by expert dysmorphologists. Methods Here, we introduce an approach driven by artificial intelligence that uses portrait photographs for the interpretation of clinical exome data. We measured the value added by computer-assisted image analysis to the diagnostic yield on a cohort consisting of 679 individuals with 105 different monogenic disorders. For each case in the cohort we compiled frontal photos, clinical features, and the disease-causing variants, and simulated multiple exomes of different ethnic backgrounds. Results The additional use of similarity scores from computer-assisted analysis of frontal photos improved the top 1 accuracy rate by more than 20–89% and the top 10 accuracy rate by more than 5–99% for the disease-causing gene. Conclusion Image analysis by deep-learning algorithms can be used to quantify the phenotypic similarity (PP4 criterion of the American College of Medical Genetics and Genomics guidelines) and to advance the performance of bioinformatics pipelines for exome analysis

Electronic properties and phase transitions in low-dimensional semiconductors

We present the first review of the current state of the literature on electronic properties and phase transitions in TlX and TlMX2 (M = Ga, In; X = Se, S, Te) compounds. These chalcogenides belong to a family of the low-dimensional semiconductors possessing chain or layered structure. They are of significant interest because of their highly anisotropic properties, semi- and photoconductivity, non-linear effects in their I-V characteristics (including a region of negative differential resistance), switching and memory effects, second harmonic optical generation, relaxor behavior and potential applications for optoelectronic devices. We review the crystal structure of TlX and TlMX2 compounds, their transport properties under ambient conditions, experimental and theoretical studies of the electronic structure, transport properties and semiconductor-metal phase transitions under high pressure, and sequences of temperature-induced structural phase transitions with intermediate incommensurate states. Electronic nature of the ferroelectric phase transitions in the above-mentioned compounds, as well as relaxor behavior, nanodomains and possible occurrence of quantum dots in doped and irradiated crystals is discussed.Comment: 70 pages, 38 figure