Methods presented in Russian and foreign scientific literature sources for processing high-arsenic copper raw materials to convert arsenic into low-soluble and stable compounds are reviewed. Hydrometallurgical processing methods are shown to be applicable for converting environmentally hazardous components into inert solid wastes while avoiding the formation of gaseous emissions. The isolation of arsenic when processing raw materials involves its oxidation and precipitation in the form of low-soluble and stable compounds. Methods for arsenic oxidation using oxygen, hydrogen peroxide, ozone, mixture of oxygen and sulphur dioxide, sodium hypochlorite are compared. Methods of oxidation by iron and permanganate ions, bacteria (biooxidation), as well as by introducing an activated carbon catalyst, are also considered. Precipitation approaches include neutralization by lime, precipitation of sulphides, co-precipitation of arsenic with iron ions, precipitation of scorodite, and encapsulation technology. As a result of the performed analysis, the authors present a promising approach for solving the problem of processing high-arsenic copper concentrates to comply with standards governing arsenic emissions into the environment, including the comprehensive processing of these raw materials using autoclave oxidation. In addition to the ensuring effective precipitation of arsenic in the form of a low-toxic compound (scorodite), this method can be used to isolate valuable components (copper, gold, silver) with their subsequent extraction into individual finished products. The obtained results establish a direction for a further in-depth study of the problem.

The present study considers solutions to problematic issues concerning the integration of distributed generation facilities into the internal power supply network of power consuming units. The possibility of ensuring reliable power supply using verified models of generating plants and power consuming units is analysed along with a description of principles for the selection of control systems for generating plants. Full-scale measurements recording significant deviations in power quality indicators, were carried out. A total capacity of distributed generation facilities operating as a part of isolated energy districts is estimated at 8.5–9 GW. In addition, in the case of operation as a part of power systems, this capacity is equal to 13.5–14 GW. Therefore, the total capacity of these facilities is 22–23 GW or 9.5–10% of the total capacity of all generating facilities in Russia. The necessity of using verified mathematical models of generating plants, as well as main synchronous and asynchronous motors, along with the correct consideration of rotated mechanism types and real load factors, is substantiated. Principles for selecting the excitation systems of generating plants, as well as coordinating parameter settings for relay protection devices in generating plants and other elements in the internal power supply networks of power consuming units are considered. Recommendations regarding the permissibility of commutations and guaranteed correspondence between electric power quality indicators and regulatory requirements in island (autonomous) operating mode are provided. Thus, the need on the part of organizations that have necessary software systems and experience in conducting complex mode calculations to implement projects for integrating distributed generation facilities is substantiated. Here, the volume and complexity of calculations is higher than in the design of standard power plants and power supply systems.

A theoretical substantiation of an environmentally friendly technology for extracting gold from mineral raw materials is presented. In terms of an alternative to conventional cyanide, the authors propose chlorine-bearing derivatives of organic isocyanuric acid (C₃H₃N₃O₃). In the studied process, this reagent combines the roles of a long-acting oxidant and complexing agent due to the resulting Cl^– ion. For experimental purposes, the rotating disc technique was applied. Experimental results were evaluated by measuring the concentration of gold in solutions using the atomic adsorption method. The theoretical characteristics of gold dissolution using the proposed reagent were studied. In order to evaluate the applicability of the revealed regularities for practical purposes, comparative indicators for leaching gold from the ore of the Byn’govskoye deposit (Sverdlovsk Oblast) using the proposed reagent, cyanide and CYCAD cyanide substitute (China) were evaluated. The dependence of the gold disc dissolution rate on temperature, as well as leaching reagent and hydrochloric acid concentrations, were studied. In disc sample experiments, the exponential dependence of the dissolution rate on the concentration of the studied reagent was established. In this case, the maximum intensity of the process is achieved at a concentration higher than 50 g/dm³. The optimum acidity level comprises 0.3–0.4 g ion/dm³ of hydrochloric acid. Despite an increase in temperature being shown to accelerate the dissolution process, this appears to be technologically unjustified. Under optimal conditions, the gold disc dissolution rate reaches 0.5•10^-3 g ion/(cm²•min), which is approximately one hundred times higher than during the dissolution by the cyanic solutions in conventional modes. Close gold extraction values were achieved in the solutions of cyanides and chlorine-bearing derivatives of isocyanuric acid during the leaching of gold from the ore under the comparable conditions. For CYCAD solutions, the same indicator is two times lower. The results of the performed studies demonstrate the high dissolution rate of gold using the proposed reagent along with the technological possibility of leaching gold from ores using this environmentally friendly reagent.

In this work, an approach for accounting and regulating the share of distributed generation in an integrated energy system is developed. In order to model an integrated energy system, a multi-agent approach was used, which presents a technologically complex system as a combination of agents, each having individual behaviour. The essence of a multi-agent approach is as follows: an integrated energy system is represented as a combination of components modelled by their agents having an individual behaviour algorithm; each element of an integrated energy system is involved in the generation of a solution and protects its interests on the basis of efficient energy supply. The implementation of this approach was carried out using the AnyLogic software environment, which includes the basic components of agent and simulation modelling, allowing any multi-agent systems to be developed depending on the application. The custom structure of the multi-agent system for integrated energy systems was developed, factoring in its performance features and interaction of objects, the main composition and types of agents of the multi-agent system being determined. The following types of agents were distinguished: consumer agent, dynamic consumer agent, network agent, manager agent of dynamic consumer, agent of centralised energy source, network agent and advisory agent. A multi - agent model of a real power supply system of a residential area in Irkutsk, having centralised and distributed energy sources, was developed. Taking into account the efficient operation of centralised energy sources, the principles for regulating the share of distributed generation in the system were proposed, allowing the total costs of energy supply to consumers to be reduced by rearranging power between centralised and distributed generation sources. The results obtained using the developed multi-agent model were used to formulate the principles of interactions of centralised and distributed energy generation sources. The redistribution of power between these energy sources on the basis of the above principles reduced the total costs by 4.22% for heat supply and 9.94% for electricity supply to consumers.

A hydrometallurgical technology has been proposed for processing the refractory part of the lining of aluminum production electrolysers dismantled and disabled for overhaul. Fluorine-containing compounds are transferred to the solution, which allows obtaining cryolite for being used in the electrolysis process. It is recommended to use solid residue from leaching (cake) with a minimum content of alkalis and fluorine as an additive to the mixture for cement production. According to the results of experiments on obtaining portland cement by traditional firing technology, the limiting content of alkali metal oxides (not higher than 4.5% by weight, calculated as Na₂O) in the leaching cake was determined, the optimum content of this additive in the charge is from 5 to 12% depending on chemical composition of lime used.

This paper examines the kinetics of corrosion for steel St3 samples covered with a latex coating 69B–2k, manufactured by Kapitel LLC (Irkutsk), by analysing gravimetric tests performed using steel samples. A 3 wt % solution of sodium chloride was used as an electrolyte. The accuracy of the obtained results was confirmed by carrying out at least two parallel experiments. Prior to coating, the metal surface of samples was carefully prepared as per GOST R 9.907-2007. Film coatings were applied onto the metal surface by threefold dipping of samples in liquid latex followed by drying within 24 hours. The quality of the coating prior to and following the experiments was assessed visually and by microphotography. Gravimetric studies were carried out under temperature control (25 ± 0.2°C) in the working area. At the same time, changes in the sample mass were recorded over a controlled time interval (from 1 to 24 hours). The results of weighing samples obtained prior to and following the experiments were analysed using a kinetic flowchart, in which the type of reaction is defined in stages in a natural sequence. Kinetic analysis of the gravimetric results confirmed the absence of characteristic signs associated with chemical interactions on the surface of steel St3 coated with latex 69B-2k. Out of the known mathematical models of phenomenological kinetics, it is admissible to use a first-order equation to describe the course of a simple reaction during heterogeneous interaction, where the penetration of reagents through a latex film comprises a limiting stage. The kinetic analysis showed that it is necessary to study the properties of latex films; a strategy for further corrosion studies was determined.

This work presents a mathematical model of thermal explosion in a medium described by a Gaussian distribution of reactivity, along with the determination of critical values for model parameters and their dependence on the distribution dispersion. The numerical solution of boundary value problems for steady-state temperature distribution in a reaction medium (a sweep method along with the iterative refinement of a source function, a half-interval method to find the critical value of the Frank-Kamenetskii parameter) was used. The grid convergence was investigated for the used difference scheme; the first order of accuracy was observed as a result of numerical evaluation of the critical value of the Frank-Kamenetskii parameter. Calculations were carried out with accuracy to three decimal places. Numerical methods were implemented as programs in the MATLAB environment. Numerical approximations were obtained for solutions of the thermal explosion equation characterised by distributed activation energy in the quasi-steady-state approximation. It was shown that the critical value of the Frank-Kamenetskii parameter is associated with the dispersion of the distribution and the Arrhenius parameter by a simple approximate analytical formula, confirmed by comparing with numerical estimates. Since the dependence of the critical value of the Frank-Kamenetskii parameter on the dispersion is described by a Gaussian function, the reaction medium becomes thermally unstable even at small values of the distribution dispersion. Calculations showed that a significant dispersion of reactivity (on the order of tenths of the average) can be observed only for chemical reactions characterised by low sensitivity to temperature (i.e. a small heat effect or low activation energy). Approximate formulas for critical conditions were also obtained for asymmetrical distribution functions. The analysis allows the proposed mathematical model to be used for assessing the thermal stability of reactive media having distributed reactivity (for example, natural materials, polymers, heterogeneous catalytic systems, etc.).

In the article, the role of coal in the energy balance of the Republic of Sakha (Yakutia) is assessed by factoring in significant coal reserves, including low-quality and local coal in hard-to-reach areas. The research was carried out using system analysis methods. To this end, the retrospective dynamics of production and consumption of fuel and energy resources in retrospect and estimates were considered. The estimates were obtained by analysing reference documents, available resources for coal mining and the calculations performed by the authors. The production and consumption of fuel and energy resources of the Republic of Sakha (Yakutia) were analysed. It was shown that coal comprises one of the main resources for power and heat generation, along with gas and water resources. Its share in the consumption of primary fuel and energy resources in 2020 amounted to 34.6%. According to the calculation results, the coal production in the Republic in the future may reach 43 million tons, which will lead to the stabilisation of the export supply of coal and the demand for fuel at power plants and boiler houses in the Republic and neighbouring regions. Projects for developing the coal-fired power industry in the Republic rely on the consumption of coal from the South Yakut coal basin. In the optimal forecast balances, the share of coal generally remaining unchanged may range from 37.8 to 38.7% by 2035. It was established that the potential for coal consumption may increase from 3.5 million tons of coil, equivalent in 2020 to 4.1–4.8 million tons of coil equivalent per year. Mining opportunities significantly exceed their demand, both at present and in the future. A system analysis of the obtained results allowed the main factors affecting coal consumption in the long term to be identified. Coal mined in the South Yakut basin comprises a reliable fuel source in the zone of centralised energy supply in the future. In areas of the Republic of Sakha (Yakutia) having underdeveloped infrastructure and low population density, coal from local deposits becomes an alternative to imported fuel if their development is economically and socially justified.

The paper aims to stabilize the roasting of zinc sulfide concentrates in fluidized-bed furnaces using oxygen- enriched air. The balance between the given excess air blast (on average 20%) and the amount of loaded charge is achieved by selecting an appropriate number of evaporative cooling elements in the fluidized-bed furnace. Through the evaluation of scientific and technical information, as well as literature sources on the research topic, data were collected on the effects produced by an oxygen excess in the blast on the quality of sulfide concentrate roasting and by a blast volume on the state of the fluidized bed. In addition, statistical data for the study were obtained by analyzing the operation of fluidized-bed furnaces at Electrozinc. As part of the study, the heat balance in roasting was determined, taking into account the following technical characteristics of fluidized-bed furnaces used for roasting zinc sulfide concentrates: fluidized- bed level, number of nozzles, furnace diameter, diameter in the bed zone, hearth thickness, and the total weight of the furnace. Relying on the operation analysis of fluidized-bed furnaces, a method was proposed to regulate the oxygen supply depending on the amount of loaded charge. The oxygen supply is regulated in order to ensure a stable excess of oxygen in the blast without causing any significant changes in the blast volume and, consequently, to maximize the sulfur removal from the charge. A decrease in the excess air blast below 15% was found to significantly degrade the quality of the resulting cinder and dust, while an increase of over 20% reduced the SO₂ content in the exhaust gases with no noticeable improvement in the quality of cinder. Therefore, the proposed method for regulating the oxygen supply to the furnace can improve the techno-economic performance of zinc sulfide concentrate roasting in fluidized-bed furnaces.

This paper discusses the development of a new procedure for finishing and hardening treatment by changing the kinematics of a deformation tool having a double-radius shape of the profile of the working surface, along with the determination of the stress-strain state in the site of elastic-plastic deformation and residual stresses in the hardened zone of the surface layer. The SOLIDWORKS 2018 software for 3D design and the ANSYS Work-bench 19.1 soft-ware using the finite element method were used to build a mathematical model of local loading. The temporary and residual stresses, the strain state in the loading zone, the depth of the plastic layer and the maximum value of the relative plastic deformation under various loading procedures of the working tool were determined. It was established that, at the reversible rotation of a double-radius roller, the values of temporary stresses are over 15% higher compared to those during static hardening, while the residual stresses are 5.7% higher. With the reversible rotation of the double-radius roll-er, the value of the maximum strain intensity becomes 2.11 times higher than that during static hardening. The intensity of the maximum residual stresses during the reverse rotation of the double-radius roller occurs at a depth 3 times greater than the indentation of the double-radius roller, rather than on the surface of the sample. The results of computer model-ling and numerical calculations indicate that the procedure of reversible rotation of a toroidal double-radius roller has the greatest influence on the intensity of the stress state in the deformation site, while the procedure of static hardening by a single-radius roller has the least impact. The obtained results suggest that the proposed technological process of surface plastic deformation based on the reversible rotation of the working tool will allow the radial tension to be reduced while maintaining the high quality of the surface layer of machine parts.