Nonferrous ore concentration
Bocharov V.A., Ignatkina V.A. On role of iron and its compounds in processes of enrichment of nonferrous and precious metal sulfide ores
A role of iron and its oxidation products in sulfide pulps is shown on the basis of analyzing the literature and the data of own researches. The determinative factors: medium pH, modifying agent concentration, mineral composition, points and procedure of flotation agent metering affecting the oxidation-reduction processes with participation of iron and the selectivity indices of sulfide minerals during flotation are designated.
Extractive metallurgy of nonferrous metals
Nikolaev I.V., Saveliev D.A. Increase of efficiency of alumina production process according to the Baeyer flow chart with the help of computer model
Alumina refinery operating according to the Baeyer flow chart is the subject of researches. The main instrument of the researches is a computer model of alumina production, which may implement its optimization. The methods have been developed, which render possible to find the extent of influence of raw material properties and process production characteristics on its economic effectiveness. The maximum attention was paid to the production processes, which constitute the Baeyer cycle: leaching, decomposition, dilution, and boil-off. The process of passing material flows through the entire Baeyer cycle with obtaining their qualitative and quantitative characteristics has been simulated. A state diagram model has been created, which allow us to determine approximately the shape and position of gibbsite solubility isotherm as function of temperature. The main result is a proposal of effective instrument providing optimization of the most important process characteristics of the alumina production based on its complex technical-economic estimation.
Lugovitskaya T.N., Naboichenko S.S., Bolatbaev K.N., Mamyachenkov S.V. The effect of lignosulphonates on elemental sulfur and zinc sulfide dispersion indices in aqueous suspensions
A new technique is proposed to determine integral and differential characteristics of zinc sulfide dispersion and elemental sulfur in suspensions on a real-time basis using technical and program interfacing of a microscope with PC. Investigations of development of particle dispersing and aggregating processes has been carried out on specific content of mesh fraction depending on surface-active reagent type (lignosulphonates) and sulfuric acid concentration.
Oleinikova N.V., Chekushin V.S., Baksheev S.P. Lead reduction in the lead sulfide – sodium hydroxide melt system
Based on thermodynamic investigations on lead reduction from its sulfide compounds with the use of electron-donor properties of sulfide sulfur, the effect of factor combination on lead metallization in the medium of melted sodium hydroxide has been studied. In the temperature range of PbS alloying with alkali (470–510 ºС), “explosive” metallization takes place reaching 95 % at t = 550 ºС; the process proceeds to completion in 15 min at t = 650 ºС; metal reduction proceeds in the diffusion range at t = 650÷500 ºС. The prescribed mass ratio NaOH : PbS (α) affects directly the yield of “lens” massive metal. The yield of massive metal is 96–98 % in the α range from 1 ,8 to 0,8. The experiments have proved that the chemistry of elemental sulfur utilization is related to disproportionation of the latter with accumulation of S2– and with possible formation of polysulfide sulfur ().
Extractive metallurgy of less-common and precious metals
Strekalova T.A., Korostovenko V.V. Raised gold extraction into solution in using combined ore beneficiation techniques
By the example of gold-bearing ores of the “Eldorado” deposit (Krasnoyarsk Area), a possibility and the conditions of increasing gold extraction at the stage of concentrate preparation to hydrometallurgical conversion are considered by means of intensification of mineral assemblage development by discharge-impulse method. Such technology allowed us to exclude the grinding stage after flotation operation. With optimal (9,2 kJ/dm3) energy of pulp processing, metal extraction into bromide solutions and thiourea solution increases by 1,2 % and 3,4 % respectively.
Casting production
Sharshin V.N., Skitovich S.V., Kechin V.A., Subbotin D.V. Investigation of processes of aluminum melt dissolution and saturation by iron
Iron-bearing built-on piece dissolution process in aluminum melts is considered. Based on the data of investigations of kinetics and iron saturation of Al-solutions, the recommendations are given for the iron-contaminated aluminum melt remelting. An intermetallic layer formation and growth mechanism is proposed.
Koltygin A.V., Tsynovnikova Yu.P., Kol’ O.A. Use of non-aqueous molding mixtures as substitute of conventional sand-argillic mixtures
Searching the molding mixtures capable of replacing sand-argillic ones, the properties of which are well investigated, is under way recently. Unfortunately, the majority of them form a mold box in the course of binder hardening, thus resulting in necessity of creating a complex system to recycle used molding mixture. In this respect, the molding mixture with the use of organobentonite as binder, which requires no changes in the green molding process, has been investigated. The effect of quantity and composition of dissolving agent on the properties of non-aqueous mixtures is estimated.
Materials science and heat treatment
Kurbatkin I.I., Podgorny D.A., Chepelenko N.V. Investigation of the effect of structural factors and composition of surface on properties of eutectic silver-copper solders used in vacuum technology
The structural changes have been considered, which take place in silver-copper eutectic solders when they are produced with the use of new production processes. Changes on the contact material surface and their effect on the solder flowing process have been investigated by microscopic metallography, local X-ray analysis, and Auger spectroscopy. The content of allowing elements in phase components of the alloys was found. The composition of films formed on the material surface has been determined. The data obtained allowed us to optimize the solder production process and improve the soldering quality.
Powder materials and coatings
Yermilov A.G., Rakova N.N. The effect of nucleation centers of process of formation of nanostructure in decomposing organo-metallic compounds
The effect of nucleation process on thermal decomposition of organo-metallic compounds (OMC) is considered. The introduction of nucleation centers into the starting OMC is found to affect the structure and the composition of the product being produced. The structure of the nucleation centers defines the structure of phases being formed and the amount of introduced nuclei defines the phase composition of the final product. An opportunity of using the decomposition products of the same OMC as nucleation centers is shown. The effect of coherent-scattering region (CSR) extent reduction for the crystalline phases formed on the nucleation centers with the greater CSR extent of the same phases has been found out. The effect begins to develop at the equality of inoculation producing and its decomposition temperatures with present OMC.
Structural macrokinetics. Self-propagating high-temperature synthesis
Levashov E.A., Kudryashov A.E., Pogozhev Yu.S., Vakaev P.V., Zamulaeva E.I., Sviridova T.A. Special features of formation of nanostructurized electrospark protective coatings on OT4-1 titanium alloy in using nanoparticle dispersion-hardened electrode materials of the TiC–Ti3AlС 2 system
The effect of nanosized ZrO2, Al2O3, NbC, W, WC and WC–Co additives into the composition of TiC–Ti3AlC2 electrode on the coating formation kinetics according to the electrospark allowing (ESA) on OT4-1 grade titanium alloy with varying the impulse discharge time in a wide range has been studied. A package of investigations of structure, phase composition, properties (integrity, thickness, microhardness, friction coefficient, wear resistance and heat resistance) and topography of electrospark coatings produced has been carried out. Optimal energy level of OT4-1 grade titanium alloy ESA-processing by new electrode materials has been determined. The introduction of a nanosized component promotes the improvement of integrity and microhardness of electrospark coatings, essential increase of wear resistance and heat resistance of titanium alloys.
Chukhlomina L.N., Maksimov Yu.M., Akhunova Z.S. Silicon nitride production by technique of acid enrichment of products of ferrosicium combustion in nitrogen
The silicon nitride (Si3N4) production process by the technique of acid enrichment of ferrosilicium and gas nitrogen interaction products in the mode of self-propagating high-temperature synthesis (SHS) has been investigated. The effect of the nature acid, its concentration, agitation of solution, and temperature of process conduction has been found. The stage character of Si3N4 + Fe composite powder interaction with hydrochloric acid solutions is shown. The apparent activation energy of iron to solution transfer process is determined. Purity of Si3N4 powder obtained is shown to depend on the degree of SHS-product nitriding. Its chemical and phase compositions are found out and the specific surface is estimated.
Surface engineering. Multifunctional films. Corrosion and metal protection
Pustov Yu.A., Filonov M.R., Anosova M.O., Kutuzov A.V., Posdeev A.I., Olesova V.N. Electrochemical diagnosis of compatibility of stomatological metallic materials after thermal treatment for application of ceramic coatings
The paper gives the results of investigating the electrochemical properties of stomatological metallic alloys after high-temperature annealing (900–1200 °C) in the air in the course of exposition in biological solution (simulating human saliva) being in stationary state and in the conditions of renewal of thermally oxidized surface. It was shown that the change of electrode potentials takes place unsteadily, giving evidence of presence of porous thermal oxide film on the metal surface. In exposing in the solution, the highest rate of sintering-out of pores can be observed for NiCrMo, VT5, VT14, CoCrMo alloys. Based on the results of EMF measurement, galvanic current in “Ti (VT1-0) – metal (alloy)” pairs as well as pulse currents in the moment of renewing the surface of one of the contact pair elements, a conclusion was made of a possibility of application of all material investigated in the pair with the control material (unannealed titanium), and the combinations most preferable with it were determined.
