Extractive metallurgy of nonferrous metals
Baksheev S.P., Oleinikova N.V., Chekushin V.S. Review of investigations on thermodynamics and kinetics of lead reduction
Lead metallization upon lead mineral and secondary raw materials processing represented by various types of chemical compounds (oxygen sulfur-containing) was investigated. The thermodynamics data on the lead reduction out of oxygen compounds (oxides, sulfates and silicates) by carbonic, hydrocarbon and sulfur-containing reducing agents at T = 298¸ 1375 К as well as out of sulfide compounds by sulfide sulfur, hydrogen and metal iron within the specified temperature interval were presented. A lesser energy consumption of the lead reduction directly out of sulfide compounds as compared with discussed oxygen compounds was assumed. Literature data on the process kinetics of obtaining metal lead were presented. It was found out that the activation energy of reduced lead out of oxygen compound by natural gas was lowest as compared with the reduction by carbon oxide, hydrogen, and their mixtures.
Mikhnev A.D., Tregubova E.V. Estimation of sampling, sample preparing, and sample analysis errors in hydrochemistry shop checking circuit at Achinsk Alumina Integrated Plant
Errors in sampling, sample preparing and sample analysis in the hydrochemistry shop checking circuit of the Achinsk Alumina Integrated Plant were estimated. It was found out that the testing error was prevailing as compared with the error relating to the analytical signal identification. It is reasonable for its decrease to use, firstly, automatic samplers, to increase analyzed raw material homogeneity and to reduce the sample delivery period.
Extractive metallurgy of less-common and precious metals
Naumov A.V. Review of world bismuth market
A review of the state-of-the-art of world and Russian markets of bismuth was made on the basis of past-year publications, and an attempt was made to prognosticate this industry development and outlooks.
Kunty O.I. Morphology of dispersed nickel electrochemically deposited in solutions of NiSO4(NiCl2)–(NH4)2SO4–NH3 · H2O system
The morphology of dispersed nickel obtained by the electrolysis in electrolytes (0,1¸ 0,5M)NiSO4(NiCl2)–0,5M(NH4)2SO4–NH3 · H2O (to pH = 8,0¸ ¸ 8,5) simulating leaching solutions of secondary metal was investigated. It is pointed out that at a current density of 20–100 A · dm–2, a sediment which consists of three structural levels: 1) spherical particles; 2) spherical agglomerates; 3) conglomerates of fragments of the second structural level is formed on the cathode. The form of first-level elements is governed by the adsorption of surface active molecules NH3 on the surface of crystalline nuclei. The second and the third levels of structuring result from high surface energies of element fragments. Spherical agglomerates are mechanically steady and govern the main characteristics of nickel powder. Their sizes decrease with increase of the cathode current density and with decrease of the nickel concentration in electrolytes and lay within the limits of 2–10 m m.
Istomin S.A., Krasikov S.A., Pastukhov E.A., Ryabov V.V. Viskosity of niobium-containing oxide-fluoride melts
The effect of Nb2O5 on the viscosity of melts based on CaF2 and CaF2–30 wt.% Al2O3 has been studied by a vibration viscosimetry method operating in the mode of decaying oscillations at T = 1523¸ 1873 K. It was found that the viscosity of melts increases and the crystallization melting interval moves to lower temperatures when Nb2O5 concentration increases from 0 up to 25 wt.% . The activation energy values of viscous flow increases from 34 up to 110 kJ · mole–1 for CaF2-based melts and from 56 up to 148 kJ · mole–1 for CaF2–30%Al2O3-based ones. The obtained data show a niobium complex-forming behavior in oxide-fluoride melts.
Yermilov A.G., Rakova N.N., Borun A.F., Dodonov A.M. Factors affecting the process of metal-carbon link formation in organometallic mixtures
The effect of the source pulp composition, evaporation extent, temperature regime on the process of metal-carbon bond formation in tungsten- and molybdenum-containing metal-organic mixtures was examined. The exothermal character of this process was found out and a mechanism for multi-stage mixture polymerization was proposed. The effect of the polymerization extent on the metal-carbon stability and product structure formed upon mixture thermal breakdown was demonstrated.
Khamkhash A., Medvedev A.S., Krylova L.N. Changes of mineral phases in processing copper sulfide concentrate
Mineralogical, granulometric and phase compositions of copper sulfide concentrate from the Erdenet (Mongolia) deposit have been studied. It is shown that it possesses a high chemical resistance when interacting with sulfurous solutions both after preliminary oxidizing calcinations as well as after mechanical activation in the planetary centrifugal mill (in “dry” and “wet” milling modes).
Casting production
Sidorov E.V. On coefficients of component distribution and some regularities of alloy crystallization in ternary systems
The computation-graphical technique was used to study the equilibrium and non-equilibrium crystallization of ternary solid solution alloys. Complex regularities of this component redistribution in solid and liquid phases have been revealed. It is shown that during the crystallization of a number of alloys the distribution coefficient of some components can vary from k < 1 to k = 1 and then to k > 1. A new graphical analysis method of the ternary alloy crystallization has been proposed. Complex diffusion processes proceeding during the crystallization of such alloys have been revealed and the peculiarities of the component redistribution at the directional solidification of samples of such alloys being important for the crystallization refining have been determined.
Materials science and heat treatment
Belov N.A., Khvan A.V. Structure and phase composition of Al–Ce–Cu system alloys in range of quasi-binary Al–Al8CeCu4 sectionThe phase diagram of the Al–Cu–Ce system in the quasibinary section area of Al–Al8CeCu4 has been investigated. The parameters of the eutectic reaction L ® (Al) + CeCu4Al8: Т = 610 °С were found out; the composition was 14 % Cu and 7 % Ce. This eutectics is of a disperse structure and the ternary compound contained is capable of fragmentation and spheroidization in the heating process (starting from 540 ° С). It was demonstrated that the area of optimal (Al) + CeCu4Al8 eutectics-based alloy compositions was within the narrow limits. That is related to the fact that at a comparatively little variation of the Cu : Ce = 2 ratio solidus sharply decreases and, as a result, the crystallization interval considerably extends.
Porozova S.E., Kulmetieva V.B., Borisova I.A., Volochai S.V. Distribution of alloyng elements and impurities in secondary zinc alloy after filtration
The effect of the ceramic foam filter structure on the microstructure and distribution of alloying elements (copper and aluminum) and impurities (iron and lead) in the secondary zinc alloy has been investigated. The ceramic foam filters (CFF) on the basis of corundum, cordierite, and silicon carbide with ultradispersed active layers were investigated. It is shown by the methods of metallographic, X-ray structure and X-ray microspectral analyses that the filtration through CFF allows receiving a homogeneous alloy with uniformly distributed alloying elements and impurities. It was revealed that filters on the basis of cordierite and silicon carbide with an ultradispersed layer containing elements of IV group of the Periodic system were of the most significant influence on the alloy microstructure and characteristics.
Wesling V., Ryspaev T. The effect of heat treatment on superplasticity of magnesium alloys
Grain’s small size of (d < 10 μm) was a required microstructural condition for the superplasticity effect to manifest itself in alloys. Ingots of comercial magnesium alloys are of a very coarse cast structure and d > 100 μm. The heat treatment conditions for such materials were investigated on the example of AZ91, AE42, QE22 and ZRE1 for producing a fine-grain structure. The optimal re-ageing temperature of hardened magnesium alloys is within the range of 300–350 °C. After hot pressing of heat treated samples an average grain size is (in μm): 6,4 (in alloy AZ91), 6,2 (AE42), 1,2 (ZRE1) and 0,7 (QE22). Better superplasticity characteristics were demonstrated by ZRE1 and QE22 alloys with a relative elongation of δ = 750 % and speed yield stress response factor m = 0,75 for Т = 420 °C and strain rate of 3·10–4 s–1. Under these conditions, AZ91 and AE42 alloys had δ ≤ 260 %, m = 0,45.
Metal forming
Akhtonov S.G., Suglobova L.V., Trusov V.A., Kropachev S.Yu., Aktuganova E.N., Kharitonov E.A., Kabanov A.A. Comparative investigations of methods to produce semi-products made of zirconium alloys
Comparative investigations of mechanical properties, macro- and microstructure of Zr–1%Nb alloy blanks produced in hot treatment of ingots applying two methods: forging and radial-shear rolling were carried out, and the quality of semi-finished and finished products were evaluated. It was demonstrated that forging had a larger depth of the structure processing as compared with rolling that forms the material state of higher characteristics of strength and impact viscosity and provides its compactness.
Baranov M.V., Guzanov B.N., Lekhov O.S., Minakov V.S. Characteristics of aluminum structure formation under conditions of high-rate high-temperature plastic deformation
The metal structure obtained in the process both of the primary crystallization and also of the possible subsequent phase re-crystallization is a very important characteristic governing metal properties. Therefore, studying the structure and mechanical properties of a metal ingot produced in the plant of joint process of continuous casting and deforming is of a considerable interest. The obtained data enable assuming at a certain reliability that the proposed scheme of hot plastic deformation used in the experimental plant for continuous casting and deforming implements in practice the full processing of metal treated within the specified geometric dimensions of ingot and strip.
Powder materials and coatings
Narva V.K., Vin T. Technology and properties of porous permeable materials based on aluminum
The investigation results of the conditions for producing (powder pressing pressure, temperature, and time of pressed product sintering) and the effect of aluminum oxide additives (5–20 wt. %) on the properties of sintered porous material made of aluminum powder and its mixture with Al2O3 powder are given. The possibility for producing aluminum-based porous (P = 30¸ 35 %) high-permeability (k = (2,0¸ 2,5)·10–13 м2) sintered material with additive of 20 % Al2O3 and maximum pore size of 1,3- 1,5 μm under the following conditions: р = 60 MPа, Т = 723¸ 823 К at an isothermal exposure of 30-60 min is demonstrated.
Structural macrokinetics. Self-propagating high-temperature synthesis
Stolin A.M., Stelmakh L.S. On role of deformation factors during combustion of porous powder materials
The deformation dynamics for two combustion cases: slow and rapid was investigated on the basis of the mathematical simulation of the compression process of chemically reacting powdered material in the cylindrical die mould. It is demonstrated that, in the general case, the deformation center is not related to the combustion area and can be in various places in relation to the combustion front and the deformation proper can go on also after the completion of the combustion process.
Process control and automation
Lisienko V.G., Volkov V.V., Ponomarev N.N., Nemchinova M.E. Problem of estimation related to temperature state during heating of nonferrous metal parts
The evaluation of the surface temperature of an aluminum cylindrical solid blank in the heating process under the conditions, when statistical characteristics of object’s noises and interferences in measurements are known in advance, has been simulated. The object’s distributed parameter linear model was substituted for a 7th-order model of lumped parameters. It was demonstrated that such substitution under examined conditions gave quite acceptable accuracy and the model retained the properties of controllability and observability. In order to build an observer on the basis of the Kalman filter special functions of the MATLAB medium were used. It was found out that the obtained accuracy of the temperature evaluations by blank sections was acceptable for a wide range of the measurement and control noise variations.
Chronicle
To 100-year anniversary of Vyacheslav Petrovich Elyutins birth
