We demonstrate the urgency of investigations of the technologies of production of hexagonal cladding tubes made of ChS82 steel (04Cr14Ti3B1V) and used for the storage of spent nuclear fuel assemblies. It is explained by the high resource intensity of the material and its low technological plasticity caused by the elevated contents of boron and titanium. The traditional technology based on the use of ingots obtained by electroslag remelting (ER) with intermediate hot deformation in a pilger mill is characterized by a metal consumption factor (MCF) that can be as high as 3.4, which determines the significance of the development of alternative resource-saving methods and technologies of production. We estimate the efficiency of using centrifugally cast billets (CCB) and the possibility of application of intermediate hot-rolled tubes 288×10 mm in size rolled in a tube-rolling plant (TRP) equipped with continuous mill with an aim to decrease the MCF and simplify the process of production of seamless hexagonal tubes 257×6 mm in size made of ChS82 steel with elevated boron content. We analyze the following three schemes of production based on the use of CCB: direct tube forming, hot extrusion, and pilger rolling. We performed plastometric tests (upsetting, tension, and torsion), metallographic structural analyses, and finite-element simulation carried out with the use of the QForm-3D software. By the numerical-analytic method (NAM) of rate setting, it is possible to show that the scheme based the use of hot extrusion is characterized by a lower MCF than the scheme with pilger rolling and, moreover, the procedure of direct forming of the CCB additionally decreases the value of MCF. Defects were detected near the outer and inner surfaces of the CCB. The results of commercial testing of manufacturing schemes reveal technological difficulties encountered in the process of production carried out with the help of CCB. The expedience and efficiency of application of the production scheme based on the use of continuous mill is demonstrated.
Refractory gold-bearing ores are technologically complex mineral raw materials due to the fine-grained dispersion of gold within a sulfide matrix, primarily pyrite and arsenopyrite, and the presence of toxic and difficult-to-remove impurities, such as arsenic, antimony, and carbonaceous compounds. These characteristics prevent efficient gold extraction by direct cyanidation without the preliminary oxidation of sulfides. Thus, the preliminary unlocking stage of the sulfide matrix, which ensures gold accessibility for subsequent leaching, is particularly important. This review organizes and analyzes modern technologies for unlocking refractory gold-bearing ores. These technologies include traditional oxidative roasting, bacterial oxidation, and autoclave oxidative leaching, as well as alternative methods such as microwave treatment, chloride leaching, ultrasonic treatment, and ozonation. The review pays special attention to the mechanism of action, technological features, advantages, and limitations of each method. The data presented in the review enable an evaluation of the potential of existing approaches and the identification of promising directions for further developing technologies for unlocking refractory gold-bearing materials.
The anodic behavior of the tin-alloyed AlFe5Si10 aluminum alloy in a NaCl solution was investigated using the potentiostatic method under potentiodynamic conditions at a potential sweep rate of 2 mV/s. The free corrosion potential of the AlFe5Si10 aluminum alloy was shown to shift in the positive direction with increasing tin concentration, whereas increasing chloride ion concentration in the electrolyte shifted this potential negatively. Higher tin concentrations in the base alloy increased the corrosion, pitting formation, and repassivation potentials. The corrosion-electrochemical behavior of the AlFe5Si10 aluminum alloy in NaCl solution indicates that alloying with up to 1.0 wt
This review outlines the key stages in the development and industrial implementation of stiff vacuum extrusion, a technology novel to ferrous metallurgy. It analyzes the distinctive features of extrusion agglomeration and their influence on the metallurgical properties of brexes (extrusion briquettes). The discussion provides a general analysis of the critical results obtained from many years of operating extrusion agglomeration lines within blast furnace and ferroalloy shops. Furthermore, the review demonstrates the effectiveness of using brexes as charge components in direct iron reduction reactors. Finally, it identifies promising directions for the advancement of extrusion agglomeration technology in the context of decarbonization and emission reduction.
Modern highly automated production lines impose stringent flatness requirements on cold-rolled strip, because even minor deviations can stop robotic processing lines. Existing active flatness-control systems, including CVC and WRB, on cold rolling mills, operate mainly in feedback mode. As a result, they cannot reliably maintain flatness during transient conditions or when processing steel grades difficult for flatness control. The main challenge is the adverse effect of the inherited condition of hot-rolled feedstock. This paper presents a three-stage approach to the predictive initial setup of CVC and WRB systems that compensates for this inherited condition before rolling begins and thereby ensures compliance with flatness requirements. In the first stage, a machine-learning model uses the geometric parameters of the feedstock and hot-rolling process data to calculate an integral feedstock quality index X, which quantitatively characterizes the inherited condition of the hot-rolled strip. In the second stage, regression models trained on historical data predict the optimal initial setpoints for the CVC and WRB systems in the critical mill stands. In the third stage, the approach operates in a closed loop that includes industrial rolling with the calculated setpoints, quality monitoring, and model adaptation based on new data. The approach was validated in industrial trials on a 2100 four-stand cold rolling mill processing high-ductility IF steel. The trials confirmed the advantage of the predictive method: all strips rolled with the calculated setpoints met the flatness requirements, whereas baseline control produced local flatness deviations in every case. The proposed approach is intended for implementation on cold rolling mills producing automotive sheet and other products subject to stringent flatness requirements. The results support stable downstream high-speed processing and help eliminate process upsets on fully automated customer lines. The approach also has potential for adaptation to other steel grades. More broadly, the predictive setup framework provides a deterministic link between the feedstock parameters and the calculated CVC and WRB setpoints needed to achieve the required flatness. Its effectiveness was confirmed in industrial trials, which showed that flatness defects were eliminated when the approach was applied. A key advantage is the potential economic benefit without capital investment through lower scrap rates and improved production continuity. The approach thus provides a basis for shifting from reactive to proactive quality control in rolling production.
