Engineering Journal of Satbayev University

The role of zirconium in the formation of structure and properties of titanium alloys during superplastic deformation

2025-02-10T11:33:56+00:00

This study investigates the effect of zirconium on the superplastic properties of titanium alloys at various temperatures and strain rates. It has been established that zirconium significantly influences the strain rate sensitivity coefficient (m), mechanical stability, and plasticity. At elevated temperatures, zirconium-containing alloys exhibit a stable m-value within a specific strain rate range, followed by a sharp decline. In contrast, zirconium-free alloys show a gradual decrease in m as the strain rate increases. The optimal temperature-strain rate conditions for superplastic deformation depend on zirconium content. Alloys with lower zirconium concentrations demonstrate high plasticity at moderate temperatures and intermediate strain rates, whereas alloys with higher zirconium content require lower strain rates to achieve uniform deformation. Beyond a certain threshold, an increase in zirconium content results in reduced plasticity and strain localization. Additionally, zirconium increases flow stress, while higher temperatures contribute to its reduction; however, this is accompanied by grain coarsening, which negatively affects mechanical properties. Microstructural analysis using scanning electron microscopy revealed that after superplastic deformation, all investigated alloys develop a fine-grained structure consisting of equiaxed α- and β-grains. The average grain size increases compared to the initial state, indicating dynamic recovery and recrystallization processes. The results confirm the feasibility of using these titanium alloys in superplastic forming technologies. The identified correlations provide a basis for optimizing thermomechanical processing parameters to achieve a balance between high plasticity and mechanical stability, which is crucial for industrial applications.

Prospects for the processing of spent automotive catalysts with the extraction of precious, rare and rare-earth metals in Kazakhstan

2025-02-19T10:56:48+00:00

Used automotive catalysts are a valuable source of rare and precious metals, which plays a key role in modern industry. These raw materials contain rare rare earths and precious metals, which makes their processing highly efficient and economically profitable. To develop a comprehensive processing technology, catalysts were studied using various analysis methods, such as chemical, X-ray, X-ray spectral, and electron microscopic analysis. The results of the phase analysis indicate that rare rare earths and noble metals are in various phase states, in the form of oxides embedded in the aluminosilicate matrix of the catalyst. These data are of critical importance for the creation of effective methods of metal extraction. The key approaches for processing these raw materials are pyrometallurgical and hydrometallurgical technologies, each of which has its own advantages and unique performance criteria. This article focuses on the physico-chemical studies of spent catalysts and the proposed method of their opening, which makes it possible to efficiently extract rare, rare-earth and precious metals. The research results can be used to optimize existing and develop new technological schemes for processing secondary raw materials.

Technology for producing pure lead-free zinc oxide from electric arc furnace (EAF) dust

2025-04-02T08:03:52+00:00

An economical and environmentally advantageous two stages method with efficient recovery of pure lead-free zinc oxide from electric arc furnace dust in parallel with clinker containing iron and carbon production for easy return to the iron smelting furnace was described. At the first stage, the electric arc furnace dust was mixed with a mixture of chloride salts and sintered at various temperatures to lead removing. In the second stage, the clinker after the first sintering stage was mixed with carbonaceous agent and sintered again to obtain pure lead-free zinc oxide. The clinker after the second sintering stage, containing iron and carbon, can be sent to the main iron production. Laboratory-scale measurements with electric arc furnace dust from one of the Kazakhstan metallurgical ferrous plants show that process allows receive lead-free zinc oxide with the total impurity content is 0.06–0.07 mass%, and the lead content is 0.001 mass%. Based on the laboratory studies carried out, a technological scheme for the two-stage processing of electric arc dust was developed to produce marketable products. The environmental benefit of the method is to reduce emissions of harmful substances into the environment associated with the recycling of electric arc furnace dust. In addition, the process allows to recycle production waste and reduce the consumption of natural resources.

Development of the coagulant obtaining technology from substandard bauxite of Kazakhstan for wastewater treatment

2025-02-15T15:41:20+00:00

One of the important environmental problems of Kazakhstan is the insufficient quality of natural and wastewater treatment, the reason for which is the lack of the main, mandatory reagent in water purification technology – coagulant. Aluminum-containing natural and man-made raw materials can be comprehensively processed in order to obtain modified mixed reagents-coagulants. One of the promising types of raw materials on the territory of Kazakhstan for the production of coagulants are substandard bauxites of the Krasnooktyabrsky deposit. This article presents a fundamentally new approach to the development of a technology for producing an effective coagulant with high coagulating properties in a wide pH range – a mixed sulfate aluminum-iron-silica coagulant (MSAISC) – when decomposing Red October bauxite with sulfuric acid with maximum extraction of aluminum, iron and silicon into a paste-like phase. Such a composition of the coagulant, called by us MSAISC (mixed sulfate aluminum-iron-silica coagulant) allows you to expand the range of action both in temperature and pH of the medium. In this sense, silicon coagulant, as well as modern aluminum polyoxychlorides, can be used without flocculant. The simultaneous presence of aluminum, iron and silicon salts in the composition of the coagulant makes it possible to combine the properties of «three in one».

Geomechanical assessment of stress-strain conditions in structurally heterogeneous rock masses of Kyrgyzstan

2025-04-28T12:09:59+00:00

This study focuses on assessing the stress-strain state of rock masses in structurally heterogeneous ore deposits of Kyrgyzstan. The primary objectives include identifying stress distribution patterns with depth, analyzing the impact of tectonic faults, and establishing the relationship between the elastic properties of rocks and their strength parameters. A comprehensive methodological approach is employed, including in-situ stress measurements using the overcoring technique to determine principal normal stresses at various depths, laboratory tests to evaluate elastic wave velocities, Young’s and shear modulus, and statistical analysis to derive regression relationships. Furthermore, the orientation of principal stresses is reconstructed, and the influence of tectonic discontinuities on the stress field within the rock mass is evaluated. The results indicate that vertical stresses in the rock mass approximately correspond to the overburden pressure, expressed as γH. Regression models obtained for competent and moderately strong rocks confirm that the experimental data lies between the values predicted by N. Hast’s relationships and those derived from hydrostatic stress distribution. The analysis of elastic properties reveals a high degree of anisotropy, where variations in P-wave velocity strongly correlate with changes in Young’s and shear moduli. The practical significance of this research lies in its contribution to developing more accurate predictive models for the stress-strain behavior of ore-bearing rock masses, thereby enhancing the design of underground excavations.

Comparative analysis of the state of desertification of the lands of West and East Kazakhstan

2025-02-27T08:20:11+00:00

The study performs an analysis and comparison of two completely different, but in some cases similar regions of West and East Kazakhstan. The influence of climate data changes, soil structure and its sensitivity on desertification in Kazakhstan over the decades of the 2000s, 2010s and from 2020 to 2024 is described using the example of West and East Kazakhstan. The author compared and detected that the soil types: Zg, XI, So, WR and KI are found both in the West and in the East of Kazakhstan exposed to degradation of soil structure. Climatic parameters, such as the temperature of the area fixed range between 3.6-4.9°С, humidity change significantly, all the time within 64% and 77%, and precipitation in different time periods changed from 416 mm to 605 mm. Using remote sensing data, the author analyzed changes in the natural environment, created visualizations and 3D modeling during the monitoring process. Thus, a set of existing research papers, statistical information and own experience were presented, since in the course of the work the results of scientific research on desertification were presented. The results of the study showed that there is an accelerated process of land desertification in Kazakhstan.