Title: Ore treatment hydrogen peroxide during heap leaching of gold
Abstract: Over the past century, many problems have been focused on the problems of low leaching rate of gold and methods have been developed to intensify the leaching of gold. Among these methods, the use of hydrogen peroxide to accelerate the leaching of gold is known. In order to intensify the leaching process, the indicators of cyanide leaching of gold from ore using hydrogen peroxide were studied. This article presents the results of assay-gravimetric, chemical, and mineralogical analyses of gold-bearing ore from the Sari Gunay Deposit (Iran). The content of sulfide sulfur ore belongs to the category of low-sulphide, by oxidation of sulphur (50.70%) to the category of oxidized ores. Thermodynamic analysis of possible reactions of ore components with hydrogen peroxide is carried out. Laboratory studies on cyanide leaching of gold have shown that the maximum recovery of gold is 52.92% at a concentration of hydrogen peroxide of 0.5%, the recovery of gold without ore treatment is 52.03%. The results of laboratory and column tests with and without treatment with hydrogen peroxide (H2O2–0.5%) were compared. Treatment of gold-bearing ore with hydrogen peroxide during heap leaching of gold increases gold recovery by 1.2% and amounts to 55.89%, without treatment - 54.69%. This increases the consumption of sodium cyanide by 0.04 kg/t.
Keywords: heap leaching gold, heap leaching intensification, gold leaching, hydrogen peroxide, oxidizer, gold.
Title: Simulation of oil pipeline shutdown and restart modes
Abstract: The paper is devoted to the simulating of non-stationary processes of shutdown and restart on the example of a section of the Zhetybai-Uzen “hot” oil pipeline. A mathematical model of thermal-hydraulic calculation is given taking into account the rheological properties of the pumping oil. The special module of the SmartTran software developed by the work’s authors carried out the calculations. In the calculations, the decrease in time of oil temperature in the pipeline during cooling and the increase in oil pressure, temperature, velocity after the restart are determined. In addition, the calculations determine the power of pumping units, heating furnaces and the power consumption, which are necessary for restart of the pipeline after the shutdown. Simulation the processes of the pipeline cooling and restart after a shutdown makes it possible choosing the optimum parameters of pumping units at pumping stations and the time of safe shutdown of the oil pipeline.
Keywords: simulation, oil pipeline, transportation, shutdown, restart, software module.
Title: Study of biohydrometallurgical technology used to recover gold from ore at a gold-recovery plant
Abstract: The article contains the results of the studies performed for the biochemical eхtraction modes for mineral raw materials using thionic bacteria Acidithiobacillusferrooxidans of a certain strain capable to oxidize sulfide minerals. A representative sample of mineral raw materials was taken, and its physical and chemical studies were performed. The optimal conditions to leach mineral raw materials with biochemical solvents based on various factors (temperature, S:W) were established. Modern physical and chemical methods of analysis were used during the study: X-ray fluorescence, X-ray phase, mineralogical, electron probe, chemical analyzes, IR methods to study the phase composition of ores and changes in the structure of minerals. The chemical composition of the ore sample quartered and crushed up to a size of -0.074 mm is as follows, wt. %: SiO2 - 60.11; Al2O3 6.2; Zn 0.016; Cu 0.10; Fe - 2.5; S 0.50; Au - 3.67 g/t and Ag - 3.2 g/t. This paper discusses various options for agitational leaching with acid pre-wash, bacterial dissection and oxidative decomposition of minerals using sodium hypochlorite. The results obtained showed that the most effective method to increase the gold recovery is to perform bacterial oxidation of ore using acidophilic bacteria At. Ferrooxidans preliminarily adapted to the material composition of the test sample, followed by treatment with sodium hypochlorite solution and cyanidation. Biohydrometallurgical ore processing provides high gold recovery (78.1%).
Keywords: ore, gold, biochemical leaching, At. ferrooxidans, sodium hypochlorite, cyanidation.
Title: Granular magnesia compositions
Abstract: The results of studies of granular materials from magnesia compositions are presented. To obtain the compositions, fillers of various origins were used: sawdust, wheat husk, rubber and cork crumbs, ash microsphere. The formulations of molding mixtures that ensure the production of granules by the method of pelletizing are determined. The factors of influence on the strength of granules at various stages of the technological process are revealed. Methods for reducing the density of magnesia granular materials by combining various types of fillers and introducing a gas-forming agent are proposed. The use of caustic magnesite ensures reliable bonding of the filler particles in the granules. Features of hydrate formation of magnesia binders allows the use of low-temperature processing of raw granules. The expediency of increasing the temperature of the salt recluse to accelerate the hardening of the porous granules is shown. Magnesia granules with a bulk density of 400 – 500 kg/m3 were obtained. The work is aimed at creating a resource-saving technology of non-annealed granular aggregates for light concrete
Keywords: Caustic magnesite, filler, composition, granules, porous structure.
Title: Technological improvement of the scheme unit reception and distribution of solution under conditions of high-pressure nature of groundwater
Abstract: This paper analyses the experience uranium deposits mine development under conditions of highpressure nature of groundwater proposed technology "pumping wells" and upgrading technological scheme unit receiving and distribution of the solution. The results of experimental study of the use of "pumping wells" in mining deposits of uranium by in-situ leaching mine "Karatau". It is proved that by using the proposed technology and circuits under conditions of the high groundwater pressure reduces the cost of procurement of cables, significantly reduced the cost of acquisition of submersible pumps, savings in the end cap. In practice, one processing unit is equipped with one unit for receiving and distributing the solution, therefore, a leaching solution with the same acidity is supplied to all injection wells. To avoid such cases requires selective supply of different concentrations of acid with the different indicators pH. The modernization of the scheme of the unit for receiving and distributing the solution was carried out by connecting two bypass lines, where one bypass line is designed to transfer the injection wells to the pumping one, and the second one is to transfer the pumping wells to the pumping one. By connecting the two bypass lines, it will be possible to supply a leach solution with a higher acid concentration, selectively to any injection well. As a result, acid consumption will decrease due to its selective supply and pH values in wells will be balanced.
Keywords:In-situ leaching, high-pressure character, «pumping wells», pH factor.
Title: Radial-shear rolling as a new technological solution for recycling bar scrap of ferrous metals
Abstract: Waste recycling of both ferrous and non-ferrous metals is a useful process for the economy of any country. This paper proposes a new technology for recycling bar scrap of ferrous metals by rolling it in radial-shear rolling mills by producing a commercial product in the form of bars with an ultrafine-grained gradient structure. Studies have shown that the deformation of bar scrap in the form of pieces of reinforcement made of steel grade 18G2S in a radial-shear rolling mill makes it possible to significantly disperse its structure by producing a gradient ultrafine-grained structure, and this, in turn, leads to the elevating of the mechanical characteristics of this steel grade. Thus, the tensile limit of the 18G2S grade steel deformed on the radial-shear rolling mill was 620 MPa (at the initial value of 365 MPa)..
Keywords:recycling, bar scrap of ferrous metals, reinforcement, radial-shear rolling, microstructure, mechanical properties.
Title: The effectiveness of the use of physical impact on the reservoir to reduce the viscosity and increase oil recovery
Abstract: This article provides a technical and economic assessment of the effectiveness of the application of physical impact on a productive formation in one of the fields in Western Kazakhstan. The world experience of using the technology of physical stimulation in the fields shows high technological efficiency. Also, in order to optimize oil production, as a result of physical impact, changes in oil viscosity, an increase in oil production and a decrease in water cut were calculated. All the Cretaceous horizons have good reservoir properties, however, the high viscosity of oil and poor consolidation of the rocks composing the horizons do not allow for the full recovery of the product. Determination of phase permeabilities in the oil-water system was carried out in laboratory conditions with joint stationary filtration. According to the calculations performed in order to optimize oil production, as a result of physical impact, the oil viscosity changed to a value of 430 cP from 700 cP, the value decreased almost 2 times. There is also an increase in oil production and a decrease in water cut.
Keywords: Physical impact, viscosity, oil recovery factor, technical and economic efficiency, technology of physical impact, geological and technical measures.
Title: Explanation of the cluster structures melting mechanism and their influence on the molten state’s physical and chemical nature
Abstract: There are results of the melts of semimetals and semiconductors of various structural groups research in the article. On the example of simplified regular Bethe lattice one can model destruction and aggregation of structures in clusters and on it’s basis to substantiate the metal melts properties in the form of nanolayers. The variety of compressibility polytherms forms in electronic melts requires typing, since their analysis makes it possible to explain the mechanism of the aggregation and dissolution processes of extended objects in melts. The article contains formulas that allow explaining the mechanism of the dissolution of cluster structures and their influence on the physicochemical nature of the molten state. There is considered the process of cluster fragmentation. Larger fragments of clusters are formed in the process of crushing, and this fact leads to the compressibility that decreases more rapidly, only after passing through the extremum it begins to increase due to the thermal loosening. The study of the function's compressibility for an extremum in the compressibility's temperature dependence also indicates the changing process of the clusters decomposition mechanisms in melts with an increase in temperature and vice versa to aggregation with a decrease in the melt temperature to the melting temperature.
Keywords: Pair potentials, radial distribution of atoms, semiconductor, structural factor atoms, molecular dynamics, density function, сluster structure.
Title: Current state of the problem of soil protection and prospect of using humic acids
Abstract: The article reviews the literature on the state of the problem of protecting the soil cover of the earth. Today, during the period of strong pollution of the lithosphere by technogenic wastes of various nature, leading to soil degradation and erosion, in measures to improve the physical, chemical, hydrological, agronomic and other properties of soils, preference should be given to the least harmless natural raw materials. These include humic acids (HA) and their derivatives, which are good adsorbents, stabilizers and fixers of dispersed systems. The study of the composition of humic acids with various water-soluble polymers and surfactants is another not fully understood area of interdisciplinary nature. Literary search for the works of Kazakh scientists shows the underdevelopment of both the extraction of humic acids and the formation of HA interpolymer complexes (IPC) with polymers and surfactants, as well as their use as fixers, structure formers of soils subject to wind and water erosion. Having large reserves of coal in the republic, a source of humic acids, it is not forgivable not to develop an integrated approach to research on the extraction of HAs, the formation of IPC on their basis and the use of new structure-forming agents to improve the degraded soils of the republic's structures.
Keywords: soil, structure formation, dispersed system, soil erosion, humic acid, interpolymer complex.
Title: Thermodynamics of formation and evaporation of lead-tin alloys
Abstract: Only a few works have been devoted to thermodynamic studies of the lead-tin system by methods including the volatile components evaporation process. When the binary system is separated into metals by distillation, the volatile component is removed from the alloy and the low-volatile component accumulates in the bottom products, that is, there are alloy composition changes over the entire concentration range. It is necessary to know the boundaries position of the melt and vapor coexistence fields on the state diagram, especially for solutions beneficiated with non-volatile metal to assess the quality of the vapor phase by the content of the low-volatile component. In this regard, the study has been completed with the purpose to clarify the values of the thermodynamic functions of the formation and evaporation of lead-tin melts required to calculate the boundaries of the liquid and vapor coexistence fields on the state diagram that enables us to judge the amount of a low-volatile component in the vapor phase under equilibrium conditions. The thermodynamic activity of lead was calculated, as well as the numerical integration of the Gibbs-Duhem equation using the substitution proposed by Darken is the thermodynamic activity and pressure of saturated tin vapor Based on the values of the saturated lead vapor pressure, determined by the boiling point method (isothermal version) for alloys predominantly of the lead edge of the phase diagram. The thermodynamic constants thus obtained will add to the base of physicochemical data and will be used to calculate the boundaries of the vapor-liquid equilibrium fields on the phase diagram, allowing to determine the possibility and completeness of the distillation separation of metals.
Keywords: Lead, tin, alloy, vapor pressure, thermodynamics, formation, mixing, evaporation, partial and integral quantities, entropy, enthalpy.
Title: Study of thermal resistance of cold mixtures with clay addition
Abstract: The article analyzes the results of heat resistance of cold-harmful mixtures with the addition of clay. The article presents the results of an experimental laboratory study of the properties of samples from CTS, obtained by various methods. The scientific novelty of the technology lies in the fact that the technology of casting in cold-rolled steel ensures high quality of the casting surface, the absence of gas defects and blockages in the casting. The selection of the composition and technological parameters for the manufacture of the mold, contributing to the production of high-quality defect-free castings, will significantly reduce their cost, which will have a positive effect on the economy of our country. The study of the change in density over time depending on the applied load was studied in a series of experiments. The density of the mixture was determined every thirty seconds during the entire time of the formation of the dispersed medium. These experiments showed that at the beginning of the formation of the shell, its density increases significantly. In works on the thermal stability of polymers, the general laws of thermal decomposition and carbonization of cyclic, spatially crosslinked hot curing polymers were investigated and it was shown that the kinetics of destruction, the composition of gaseous products, the amount of coke formed and its properties depend on the properties of the initial polymers - the degree of crosslinking of molecular chains, chemical structure, the presence of impurities of catalysts and other curing conditions, as well as the heating conditions - speed and temperature. The article summarizes some of the results of the study, which is most appropriate for thin-walled steel castings to use the following mixture composition: filler - quartz sand; binder - clay of the Kazakhstani deposit, epoxy resin, hardener.
Keywords: mixture, shape, properties, heating, metal, heat resistance.