Metallurgist最新文献

We substantiate the proposed design features of a ballistic separator intended for the operation (sorting of industrial waste) under the domestic conditions. The proposed model would enable us to perform targeted sorting of 2D and 3D fractions of industrial waste created by domestic enterprises with regard for the specific features of operating conditions and the types of waste specific for our country. This would help us to increase the fraction of reused industrial wastes. We present the design of a ballistic separator developed in accordance with domestic GOST standards and perform dynamical computations justifying the created model aimed at guaranteeing the possibility of correct and efficient operation of the equipment.

We consider the main principles and approaches used for the development of a predictive model aimed at minimizing the downtimes of equipment used for the production of pipes in continuous rolling mills. We perform comparative analysis of the available modern failure-prediction methods, including machine-training algorithms, artificial neural networks, and mathematical models. An upgraded system of data collection and transmission guaranteeing the possibility of efficient integration of predictive algorithms in the process of production is presented. We study two methods that can be used for constructing the models, namely, gradient boosting and artificial neural networks. The application of artificial neural networks makes it possible to attain a predictive accuracy of 99.6%, which exceeds the characteristics of traditional methods and promotes a decrease in the downtimes of equipment. The obtained results can be used for the improvement of control systems of the manufacturing processes both in metallurgy and in other branches of industry.

Various reagents can be employed during the hydrometallurgical processing of aged clinker for the sequential dissolution and subsequent extraction of non-ferrous and precious metals into marketable products. However, due to the significant presence of coke in the clinker, the preg-robbing effect occurs. This study investigates the sorption properties of the coke component of clinker with respect to copper and zinc in sulfuric and citric acid solutions and with respect to gold in sodium dichloroisocyanurate, cyanide, and thiocarbamide solutions. The results demonstrate that coke and mineral particles in clinker exhibit different sorption activities toward cations and complex ions of non-ferrous and precious metals depending on the solution type and particle size. The degree of copper sorption in sulfuric acid solutions ranges from 5.03 to 11.6%, depending on the particle size of the coke. For zinc, the range is from 0.27 to 0.81%. In citric acid solutions, the values range from 7.62 to 54.6% for copper and from 7.62 to 28.6% for zinc. The degree of gold sorption fluctuates widely: in cyanide solutions, it ranges from 1.23 to 91.12%; in sodium dichloroisocyanurate solutions, it ranges from 38.8 to 91.16%; and in thiocarbamide solutions, it ranges from 4.76 to 5.7%. As the material is ground and the surface area increases, the preg-robbing effect intensifies predictably. The preg-robbing effect depends on the reagent concentration. In cyanide solutions, the conditional degree of gold sorption increases nearly tenfold as the NaCN concentration varies from 0.5 to 10 g/dm³. Conversely, in sodium dichloroisocyanurate solutions, the degree of gold sorption decreases from 80 to 40% as the reagent concentration increases from 5 to 10 g/dm³. Additionally, sorption kinetics are faster for chlorinated solutions. Within 80 min, gold sorption reached 23.6% from cyanide solutions and 85.6% from chlorinated solutions. It was determined that the preliminary removal of coke through flotation did not yield positive results. Regardless of the degree of clinker grinding, extraction of sorption active carbon into the froth product is incomplete. Flotation tails inevitably contain a significant amount of coke, which results in low gold extraction during the leaching of the tails.

The process of operation of tuyeres with ceramic heat-insulation insert in the blow channel may be accompanied by the gradual destruction of the ceramic, which may lead to changes in the conditions of heat exchange between the tuyere and gases and, hence, to shortening of the service life of the tuyere and elevation of the heat losses with cooling water. As one of the causes of this kind of destruction, we can mention significant changes in the gas-blow parameters, e.g., an increase in the natural-gas (NG) combustion. In this connection, we study the effect of NG combustion on the thermal conditions of the tuyere and its elements. A finite-element model was created by using the Ansys software. The proposed model included the blow channel, the tube for NG supply, and the ceramic insert. As a result of the Ansys simulation, it was shown that mean values of temperature of the gas-blow flow and the insert decrease as the natural gas combustion increase. At the same time, a local increase in these parameters is observed under the gas tube in the direction of blowing, which leads to a decrease in the resistance of the insert. In addition, we also analyze the influence of the inner diameter of the gas tube used for feeding NG into the tuyere blow channel on the gas dynamics and the process of heat exchange in the air tuyere. As the diameter of the tube for NG supply becomes smaller, its stream deeper penetrates into the blow flow and mixes with it more intensely. This increases the efficiency of combustion in the areas of the flow located at larger distances from the insert surface. This decreases the temperature of tuyere elements and, hence, lowers the probability of fracture of these elements. In order to increase the resistance of the insert and improve the heat parameters of blown gases, it is recommended to decrease the gas-tube diameter down to 30 mm.

In this study, copolymers were obtained and their synthesis procedure was refined to produce protective polymer coatings. Different fillers were selected for obtaining polymer coating, such as silicon production waste (microsilica) and titanium dioxide, as well as the combination thereof. Two copolymers (No. 1 and No. 2) and seven series of polymer coatings were developed. The obtained polymers exhibit good adhesion, which is a requirement for composite protective coatings. An experiment was conducted to determine the corrosion resistance of metals exposed to aggressive media, and to determine the hardness and thickness of the resulting polymer coatings. For example, a corrosion score of 2 was achieved for the polymer coating with titanium dioxide filler exposed to aggressive media (5% NaCl and 5% KOH solutions), while a corrosion score of 3–4 was achieved in acidic and 10% KOH media. A polymer coating with microsilica filler demonstrated a corrosion score of 2 in saline and acidic aggressive media, while such coating underperformed in alkaline media, exhibiting a corrosion score of 4. The best corrosion resistance values are demonstrated by the combined styrene polymer coating, consisting of methyl methacrylate and butyl vinyl ether, with a corrosion score of 2 in saline and acidic media and a corrosion score of 4 in alkaline media. The combined coating, consisting of methyl methacrylate, maleic anhydride, and butyl vinyl ether, shows the worst corrosion resistance characterized by corrosion scores of 4, 5, and 6 in 10% H₂SO₄ and alkaline media (5 and 10% KOH), respectively. At the same time, the developed polymer coatings have satisfactory adhesion properties even after exposure to aggressive media.

Increased corrosion resistance during operation in aggressive media, as well as high wear resistance, determine the need for products with intermetallic coatings based on Fe–Al alloys in the fields of mechanical and electrical engineering. In metallurgy, alloys of the Fe–Al system can also be used as alloying additives. Common methods that are currently used to produce such alloys and coatings mainly include multi-stage and energy-consuming processes, making it important to search for more feasible methods. One of the alternatives is a single-stage redox process for producing intermetallic alloys of the Fe–Al system by exothermic remelting of thermite charges that include iron scale and active aluminum as components. The chemical composition and properties of the finished products, obtained as a result of such processes, are largely determined by the ratio of the initial components in thermite mixtures, their pre-conditioning, and reaction conditions. The paper presents the results of an experimental study aimed at establishing the effect of preheating thermite charge and refractory mold on the aluminum content in the resulting iron-aluminum alloys produced by aluminothermy, their structure and microhardness values. The results are presented in comparison with the experimental data obtained without the combined effect of preheating thermite charges and molds.

This article examines the technological aspects of producing high-strength, sparsely alloyed alloys using hot deformation. The primary focus is optimizing the alloy composition using inexpensive alloying elements, such as nickel oxide, to reduce production costs without compromising mechanical properties. The study also investigates the impact of hot deformation parameters, such as temperature and porosity, on the mechanical properties of the material. Additional plastic deformation improves the mechanical properties of the resulting steel. These findings can be applied to developing cost-effective materials for the automotive industry, mechanical engineering, and other sectors.

Comprehensive studies and thermodynamic calculations were conducted for the cladding layer steel of bimetallic sheets produced by electroslag surfacing, using various chemical compositions. The combined results of these calculations, laboratory investigations, and corrosion testing showed that the cladding layer steel with reduced carbon and chromium content can still provide sufficient corrosion resistance—comparable to that of 08Kh13 steel that meets the GOST 5632 requirements.

We develop a complex technology of separate processing of fine dust including the procedure of preliminary firing of dust with removal of arsenic from the technological scheme with subsequent application of a hydrometallurgical scheme for the extraction of copper and rhenium: sulfuric-acid leaching of cinder with cementation separation of copper with iron, and extraction of rhenium from the solution. Complex analytical studies of the intermediate and final products were carried out by the methods of atomic-emission spectrometry with inductively coupled plasma and X-ray phase analysis. The compositions of liquid solutions were determined by the method of chemical analysis. The rhenium contents in the original solutions and extraction products were determined by the methods of colorimetric and chemical analyses. This guaranteed the possibility of step-by-step quality control of the obtained products in the course of realization of the technological cycle of processing. As a result of laboratory investigations, we established the following optimal parameters of copper cementation: a temperature of 333°K (60 °C), S:L = 1.5, and a duration of the process equal to 60 min for which we obtained powdered cement copper with the following composition (wt.%): 82.0 Cu, 09.27 Pb, 1.49 Zn, 0.19 As, 0.72 Fe, 0.03 Re, 3.43 O₂; balance 11.89. The extraction of copper into a commercial product was as large as ~98%. We obtain new data on the extraction of rhenium from sulfuric-acid solutions of the process of cementation by using an extractant containing (wt. %): 10 trialkylamine (TAA), 80 kerosene, and 10 di-2-ethylhexanol. On the basis of the indicated components, it is possible to choose the composition of the extractant for the processes of extraction of dusts of different types and compositions. We obtained commercial ammonium perrhenate with a rhenium content of 69.17% corresponding to the AR‑0 grade. The end-to-end extraction of rhenium into ammonium perrhenate is as high as 93%.

This study investigates the causes of abnormal pearlite morphology, which adversely affects the mechanical properties of steels. The analysis is based on current models of pearlite colony growth. Experimental evidence confirms that oxygen dissolved in the solid solution alters the structure of interphase boundaries and promotes morphological degradation. In contrast, oxide inclusions and porosity are found to have no decisive effect on the formation of abnormal pearlite.