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Izvestiya. Non-Ferrous Metallurgy

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Nonferrous ore concentration

Korsak L.L., Lygach V.N. Gravitational-centrifugal processes to enrich ore minerals
The efficient ecologically clean and resource-saving technology to concentrate free-flowing compounds of minerals has been developed on the basis of the analysis of gravitational-centrifugal methods of enrichment and means of improving their efficiency. The offered method can be used in building, metallurgical, and mining industries.

Extractive metallurgy of nonferrous metals

Oleinikova N.V., Chekushin V.S., Baksheev S.P. Metal reduction from sulfide compounds
The current conceptions concerning metal reduction from oxides and sulfides are based on realization of dissociative processes connected with formation of simple substances. Metal sulfides can be considered as compounds of the opposite-charged particles forming due to combination of electrostatic and coordination binding in the Mez+–S2– system. Metal reduction from such compounds using the electron-donating properties of sulfide sulfur is an electrochemical process with participation of the electrode couple Mez+ и S2– in conditions of internal electrolysis in the system providing salvaging of the formed free sulfur due to chemical reactions. The liquated caustic soda is offered as the electrochemical medium; in presence of caustic soda disproportionation of free sulfur is running with accumulation, first of all, of sulfide and sulfate sulfur. The reaction leads to irreversibility of the reduction process.

Zaikov Yu.P., Arkhipov P.A., Plekhanov K.A., Ashikhin V.V., Khalimullina Yu.R., Chebykin V.V., Molchanova N.G. Thermodynamic characteristics of Pb–Sb alloys
Thermodynamic properties of Pb−Sb alloys containing 20- 95 % (mol.) Pb are studied by the measuring method of EMF equilibrium values in a temperature range from 723 to 873 К in the liquated mixture of potassium chloride and lead. Partial and integral thermodynamic characteristics of the system are calculated and small negative nonideality is noted. The extreme of integral shift functions is found in the field of 0,55 mol. Pb. The system cannot be attributed to the regular solution as the excess entropy perceptibly facilitates the nonideality and the excess Gibbs free energy considerably differs from the heat of mixing.

Tuzhilin A.S., Lainer Yu.A., Surova L.M. Physicochemical properties of aluminum hydroxychloride of various base strength
Physicochemical properties of aluminum hydroxychloride (AHOС) of a various base strength (1/3, 2/3, 5/6) have been studied. Dependences of their density and viscosity on concentration and temperature of solutions are plotted. The data is given on pH, the temperature of crystallization of AHOC solutions of a various base strength versus the Al2O3 content and Al : Cl proportion in the solution. It has been established that the AHOC quality depends on presence of definite aluminum forms: monomers, oligomers, and polymers. The degree of polymerization of various hydroxy-complexes contained in AHOC solutions is estimated. It has been found that the polymeric component has the effect on density, viscosity and temperature of freezing of solutions of aluminum hydroxychlorides of a various base strength.

Extractive metallurgy of less-common and precious metals

Balgaeva F.Sh., Medvedev A.S. Additional rhenium recovery from roasted products after oxidizing roasting of poor molybdenite concentrate in rotary tubular kiln
Studies have been made on the effect of various oxidizing agents during leaching upon the degree of recovery of rhenium remained in the roasted product as a result of incomplete sublimation in the course of oxidizing roasting of the molybdenite concentrate in the tubular kiln. Its maximum recovery (αRe = 88 %) is attained when manganese concentrate is used. It has been found that for the Almalykskiy Integrated Iron-and-Steel Works the most reasonable oxidizing agent is the mixture of nitrogenous and sulfuric acids (αRe = 71÷73 %); with that, practically complete cleaning of the roasted product from copper takes place (≤ 0,05÷0,07 % Cu is remainned in the latter). Possible separation of molybdenum and rhenium having passed into the solution, using the settling and ion-exchange methods is demonstrated.

Istomin S.A., Krasikov S.A., Pastukhov E.A., Ryabov V.V. Electrical conductivity of niobium-containing oxide-fluoride melts
The influence of Nb2O5 on electrical conductivity of melts based on CaF2 and CaF2–30% Al2O3 has been studied using the alternating current bridge method at a frequency of 5 kHz, in the temperature range from 1500 to 1900 К in the oxidizing medium. It has been found that with increase of Nb2O5 concentration from 0 to 25 % conductivity of melts decreases and the energy of conductivity activation steadily rises. The obtained results agree with viscosity investigations and point to complex-forming behavior of niobium in the oxide-fluoride melts.

Medvedev A.S., Malochkinа N.V. Sublimation of molybdenum trioxide from used catalysts of hydraulic cleaning of petroleum products
Investigations have been made on the effect of a temperature, process duration and a layer height in processing by sublimation of deactivated catalysts based on molybdenum and cobalt oxides used in hydraulic cleaning of petroleum products from sulfur. Difficulties arising in processing of such industrial waste were discussed and means for their elimination were offered.

Katkov A.L., Malov E.I., Koptenarmusov V.B., Ismagilov Z.R., Medvedev A.S. Gas cleaning from sulfur compounds
It is demonstrated that Fe- Mn sorbents made on the iron-manganese based concretions of the Gulf of Finland possess sufficiently high capacity (≥15 % by mass) as to sulfur compounds (H2S, RSH, SO2). The obtained results enable us to estimate them as the new, multipurpose, perspective material for gas cleaning from sulfur compounds in different branches of industry. The advantages of the Fe- Mn sorbents as compared to the other materials lie in the possibility of their regeneration for repeated usage, the high sorption capacity, and cheapness.

Istomin S.A., Pastukhov E.A., Krasikov S.A., Ryabov V.V. Electrochemical reduction of niobium from oxide-fluoride melts in electroslag melting
Regularities of electrochemical reduction of niobium from oxide-fluoride melts in electroslag melting (ESM) have been revealed for different electrical conditions. It is established that use of the assymetrical current in ESM essentially improves technological parameters of the electrolysis. The experimental data made possible to develop the program correcting the electrical conditions of melting depending on the Nb2O5 content in the oxide-fluoride melt in order to reach the assigned niobium concentration in the metal ingot.

Materials science and heat treatment

Dolgopolov N.A., Petelin A.L., Rakov S.V., Simanov A.V. Penetration of liquid tin along grain boundaries and triple joints of aluminum
Description is given on new methods of studying the liquid-metal etching grooves occurring as a result of wetting and penetration of a liquid phase on triple joints and boundary lines of grains in the Al–Sn system. Investigations were conducted using the layer-by-layer method of polishing the end surface of the wetted sample. The obtained polished sections were studied by the optical and electronic scanning microscopy method. It was shown that the groove depth did not practically vary along one boundary of the grain and on approach to the triple joint, increased. The depth of Sn penetration on the triple joints is much greater than along grain boundaries. It was demonstrated that the solid solution was formed on Sn base as a result of wetting processes in the triple joint.

Gushchin A.N., Pachurin G.V. Fatigue damage of welded joints made of commercially pure titanium after thermal-cycle treatment
Presented here are investigation results of the structural condition, variations of mechanical behavior in static and cyclic loading of welded joints made of commercially pure titanium after thermal-cycle treatment (TCT). The quantitative estimate of fatigue damage is given with respect to change of the sample relative bend deflection at the strain cycle stage up to the moment of the main crack opening displacement and extension depending on the number of TCT cycles.

Metal forming

Polyakov A.P. Power parameters of impact extrusion process of incompact wire blank
The mathematical model of the impact extrusion process of the incompact blank through the cone die body has been developed. It is grounded on superposition of solutions of the following problems: pressing of the powder material in the cylindrical compression mold and impact extrusion of the incompressible material. The model makes possible to determine the minimum tool velocity enabling execution of the indicated process. It is demonstrated that irrespective of the blank-to-tool mass ratio, depending on the friction coefficient, the cone angle of 25−40° of the cone die body is considered optimum for the impact extrusion process.

Powder materials and coatings

Rudneva V.V., Galevsky G.V. Investigation of thermal-oxidative resistance of high-melting carbide and boride nanopowders
Investigations have been made on thermal-oxidative resistance in the air of nanopowders of carbides and borides of vanadium, titanium, chromium, zirconium, and also silicon carbide. It is found that with respect to the temperature of beginning of oxidation in the air, they are arranged in the following rows: carbides – TiC (548 K), VC and Cr3(C0,80N0,20)2 (553 K), ZrC (560 K), SiC (905–913 K); borides − VB2 (620 K), TiB2 (643 K), CrB2 (763 K), ZrB2 (823 K). The investigation results make possible to recommend the carbides and borides nanopowders for use as strengthening phases of composite coatings operating in oxidizing mediums at temperatures not exceeding the specified temperatures of oxidation beginning. Nanopowders of chromium and zirconium borides and silicon carbide can be considered as equivalent substitutes of diamond nanopowders in structure of composite coatings.

Panov V.S. Nanotechnologies in production of hard alloys (review)
Publications review is presented on ultrafine and nanosize powders of wolfram and its carbide, engineering of their reception and making of hard alloys WC−Co on their base. The main fields of application of hard alloys with nanosize structure elements are noted.

Structural macrokinetics. Self-propagating high-temperature synthesis

Guryn S.V., Pogrelyuk I.N., Fedirko V.N., Dovgunyk V.M. Use of diffusion multi-component coatings for improvement of titanium antifriction properties
Investigations have been made on the wear-resisting property of comercially pure titanium of the VT1-0 brand with multicomponent coatings obtained by diffusion saturation by interstitial elements in the pair with bronze BrAZh9-4l at a specific load of 2 MPa using the disk-inset coupling pattern. It is found that carbonitride and carbooxide coatings permit efficient improvement of the titanium antifriction properties without treatment and also of titanium after single-component saturation (oxidation, nitriding, carbonization). The obtained results point to the positive effect of the gradient underlayer on the titanium wear-resisting property.

Economics and management

Galevsky G.V., Rudneva V.V., Yurkova E.K. Nanomaterials and nanotechnologies: estimations, trends, prognoses
The analytical investigation on the current state of nanotechnologies in the world has been carried out adhering to the following criteria: the quantity of registered patents, the number of published works and investable funds. Pursuant to the aforesaid, the world leaders in the field of nanotechnologies are the USA, Japan, countries of the European Union, and China. The advanced fields of nanoindustries and dominating trends of its development are outlined. Substantial growth of volumes of production of science-intensive products grounded on application of nanotechnologies is forecasted.

Chronicle
The 65-th Anniversary of Stanislav Stepanovich Naboichenko

No 2 (2007)


ISSN 0021-3438 (Print)
ISSN 2412-8783 (Online)