Vol 61, No 5-6 (2017)

The finite-element method is used to study the effect of the design parameters of the die on the production of hollow brass parts by cold direct extrusion and expansion on a cone punch. The results are compared with data on conventional indirect extrusion. The elastic deformation and increase in the temperature of the metal during cold extrusion are taken into account. Intermediate and final shapes and dimensions of workpieces are determined by simulation. The dependence of the extrusion force on the tool displacement and the distribution of normal stress over the tool–workpiece contact surface under the maximum force is established. The stress-strain state of the workpiece during extrusion is determined. The distribution of stress intensity, strain intensity, and temperature over the deformed workpiece at the final stage of extrusion is plotted. Rational design parameters of a die for direct extrusion and expansion are proposed.

The article is devoted to studying the possibility of preparing iron concentrates from fine classes of dumped fly ash of Far East thermal power plants by means of dry magnetic separation using a laboratory pulsed magnetic field separator. Process indices are compared for ash separation in different types of magnetic separators. Characteristics of a laboratory pulsed magnetic field separator and experimental scheme are provided. Separation products are analyzed and separation indices are calculated.

By finite-element simulation of the rolling of a Ø957 mm wheel blank on a horizontal six-roll wheel-rolling mill, it is established that rolling resulting in a 18–20 mm axial reduction of the rim minimizes its thickness variation and prevents an abrupt change in the thickness of the web at the junction between its forged and rolled portions.

An unfavorable effect is established for a high sulfur content on the high-temperature strength properties of single-crystal alloy ZhS36 in stress-rupture tests based on 500 h, on the average number of cycles to failure during low-cycle fatigue tests, and also on coated alloy isothermal heat resistance. The unfavorable effect of sulfur may be overcome by alloy refinement with lanthanum followed by melt filtration through a ceramic foam filter during casting. Metallographic study confirms the results obtained for the effect of alloy refinement with lanthanum.

Electrochemical preparation of lead from lead-containing waste in molten alkali-carbonate is described. The dust studied forms during shaft smelting of lead battery scrap being a technogenic resource with a high lead content. An ecologically clean process is developed for electrochemical processing of technogenic lead-containing raw material in molten electrolyte consisting of 60–95% NaOH and 5–40% Na₂CO₃. A large laboratory electrolyzer is constructed and prepared and tested with a current strength of 200–600 A. The use of plant shaft furnace dust from lead battery treatment makes it possible to obtain molten lead at a cathode and oxygen at an anode. There is no rapid evaporation of lead metal, lead compounds, and molten alkali-carbonate with an electrolysis temperature of 490–550°C.

The possibility is studied of preparing polymetal specimens of Ti and Ti–6Al–4V by direct laser deposition. The microstructure of deposited specimen zones given heat treatment shows a transition zone from (α+β) phase from the side of Ti–6Al–4V alloy to α-phase from the Ti side. No cracks are observed within the structure. With a change-over from Ti–6Al–4V to Ti microhardness varies from 380 to 200 HV.

Manganese-containing ores in Russia and prospects for expanding the resources by including ferromanganese nodules (FMN) are analyzed. Processes for manganese-containing materials are reviewed. The combined pyro-hydrometallurgical processing of deep-water ferromanganese nodules from the Clarion–Clipperton Zone in the Pacific Ocean is described. The results of studies on the sulfating roasting of FMNs with pyrite and the results of the one-stage neutral leaching of cinders are presented. It is concluded that it is promising to combine the processing of nodules and preliminary roasting to produce saleable concentrates of manganese and non-ferrous metals.

Possibilities are considered for a model-based decision support system developed and put into pilot operation at the Magnitogorsk Metallurgical Combine (MMK) for appraisal of operation and prediction of process situations in blast furnaces. The main model blocks make it possible to calculate material and heat balances; model heat, slag and gas dynamic conditions of blast furnace operations; select burden composition; calculate the viscoplastic iron-ore materials zone; and predict process situations. The model system is implemented as a complex of program modules and integrated into the MMK information system. A module for calculating melting material and heat balances includes both fulfilment of overall generally accepted balances, and calculation for balances of iron, sulfur, manganese, and titanium. A Slag Regime program module makes it possible to determine the most important properties of melted slag for implementation of normal slag conditions of smelting, to find the ratio of iron-ore materials providing slag of required viscosity and viscosity gradient, and to produce cast iron with required sulphur content. A Gas Dynamics of Blast-Furnace Smelting program module accomplishes calculation and visual display of gas dynamic characteristics of a burden layer as well as assessment of the change in pressure drop and degree of burden balancing in separate zones of the furnace in the design period with the change of burden parameters. A program module built into a balanced model of the UrFU–MMK blast-furnace process makes it possible to find iron ore compositions providing preparation of slag of the required properties with respect to viscosity and viscosity gradient, and makes it possible to prepare cast iron of the quality required with respect to sulfur content. A Viscoplastic Iron-Ore Materials Zone of Blast Furnace program module performs model calculation of a set of parameters specifying radial nonuniformity of charge and gas flow distribution in blast furnaces. The module includes calculation of temperature characteristics of iron-ore materials used for smelting, which makes it possible to display the shape and position of the cohesive zone in the profile of the furnace in question. Some results are provided of practical application of the system developed, and recommendations are given for certain aspects of resolving production tasks using the model-based decision support system.

Achievements are considered for contemporary metallurgy and metal science in improving quality and operating properties, and also trends in the development of low alloy steels for oil and gas pipelines. The possibility is analyzed for using ultralow-alloy austenitic martensitic steels as promising structural materials for seamless pipes and connections for main pipelines. The most essential parameters for composition and technology affecting a set of steel mechanical properties with a low-carbon microstructure are revealed.

Interest in developing new compositions and technology for preparing foam aluminum is explained by the existence for objects of this material of an unusual set of properties: low density, low thermal and electrical conductivity, good resistance to the action of fire, ecological cleanliness, and capacity to absorb impact energy effectively. Foam aluminum is prepared by liquid- and solid-phase methods, and mainly from primary materials, which is quite expensive. One of the solid phase (or powder) methods is mechanical alloying, which is a most promising direction for composite material production. This is one of the most contemporary methods for preparing precipitation hardening ceramic particles of composite materials based on nonferrous metals. Foam aluminum may be considered as a composite where instead of ceramic particles there are particles of porofor TiH₂. Therefore, mechanical alloying may also be considered as a promising method for its preparation. The method includes treatment of powder components and their mixtures in high-energy mills followed by consolidation of a uniform activated mixture in order to prepare a semiproduct or finished component. Another advantage of mechanical alloying is the possibility of using aluminum alloy production waste, which significantly cheapens production (raw material component in the cost of production is reduced by 45–65%). Results are provided for studying the process of modeling and development of technology for preparing foam aluminum from aluminum secondary raw material.

The problem of improving the efficiency of processing of rich gold-bearing concentrates is considered. A review and the critical analysis of existing ways of processing concentrates is provided. Special attention is paid to cyanide leaching that is a priority way of processing gold-bearing concentrates in gold-extraction plants using a cyanide cycle. As applied to the gravitational concentrate of Berezovsky Mine, measures are developed aimed at accelerating leaching of coarse gold. Features of gold dissolution using oxidizing agents as an alternative to oxygen are studied: hydrogen and calcium peroxides, and potassium bromate. Research and laboratory verification of technology of gold cyanide leaching with chemical activation of the process are performed. Based on research results, an operational section has been planned and introduced for processing of rich gold-bearing concentrates at the Berezovsky Mine enterprise. With the use of hydrogen peroxide compared with traditional conditions, the leaching rate for gold increases by a factor of 1.5–2. With an initial content in concentrates of 100–500 g/ton under comparable conditions, the content in tailings decreases from 10–15 to 1–3 g/ton. Commercial operation of the technology developed shows that gold extraction from concentrates reaches 98–99%, and at the same time loss of gold with dump tailings is reduced by 4 kg a year.

The possibility of using cryogenic treatment technology for tool steel of grade Kh12VMF in preparing rolls for a profile-bending mill is analyzed. The nature of the effect of cryogenic treatment on the structure is considered: proportion of residual austenite and secondary carbide distribution, mechanical properties, and wear resistance of steel analog AISI D2. Results are analyzed for this experiment under Severstal conditions for improving the wear resistance of roundhead rolls by cryogenic treatment. Preliminary evaluation is provided for the efficiency of using cryogenic treatment in the production of bent rolled product.

The authors’ affiliation should read Kremenchuk Mykhailo Ostrohradskyi National University, Kremenchug, Ukraine.