Extractive metallurgy of nonferrous metals
Voldman G.M., Teterin V.V., Ovchinnikova N.B., Sidorov V.A. Universal procedure to determine kinetic leaching parameters
A procedure has been proposed for calculation of the kinetic parameters. It demands no knowledge of the analytical equation describing the dependence of process proceeding degree on its duration. When using the procedure the experimental values of the process proceeding degree are compared with the values produced for the same process duration by solving the differential kinetic equation with the help of one of the numerical techniques. The unbiased estimators of the kinetic parameters can be found by minimization of the sum squared deviations of calculated and experimental values. This procedure is easily realized by standard means of the Microsoft Excel table processor. Its application is described for determining the values of serpentinite leaching kinetic parameters by hydrochloric acid.
Blinkova E.V., Eliseev E.I. Kinetics of zinc oxide dissolution in aqueous solutions of acetic acid
The mechanism of zinc oxide dissolving in water solutions of acetic acid were investigated by the rotating-disc method. The effect of temperature (283–343 K), disc rotating rate (1,0–16,2 Hz), acetic acid concentration (0,6–150 g/dm3) on the ZnO dissolution velocity was considered. The process was found to proceed under the combined conditions. The values of apparent activation energy for kinetic and diffusion modes were 53 and 11 kJ/mole respectively. The reaction order is 0,8 as to the acetic acid concentration. The equations were derived for both modes of ZnO dissolution in water solutions of acetic acid to provide satisfactory coincidence of the experimental and design specific velocities of the process considered. Temperature increase (T > 323 K) results in exchange in the mode: dissolution from the kinetic mode proceeds to the diffusion one. The diffusion limitation is related to formation of a zinc acetate film on the sample surface.
Alkatsev M.I., Kondratiev Yu.I., Alkatsev V.M. Dependence of zinc cathode efficiency and specific energy consumption on different factors during electrolysis of pure sulfuric solutions
The effect of current density, temperature, zinc and sulfuric acid concentration on the zinc cathode efficiency during electrolysis of pure solutions containing impurity traces was carried out by the design method of experiment. The regression equations were obtained resulting in the optimal electrolysis parameters.
Litvinov A.V., Poilov V.Z. Removal of sulfates from flotation carnallite melts
The purification process of flotation carnallite melt from sulfate salts dissolved was proposed to carry out by reduction by oil coke. The methods of introducing a reducing agent into the melt were investigated. The mechanism of the purification process was studied at T = 550¸ 790 ° C. Pilot and industrial studies of the carnallite melt desulphurization process were carried out. The residual concentration of sulfate ions was < 0,05 % without contamination of the electrolyte by carbon. The method developed allows us to use the flotation carnallite as stock material for production of magnesium metal by electrolysis.
Extractive metallurgy of less-common and precious metals
Zhuchkov I.A., Mineev G.G. Electrochemical investigations of gold dissolution in chloride-hypochloric medium
Electrochemical investigations of the processes proceeding in the chloride-hypochloric medium over gold electrode were carried out using a rotating electrode and a pulsed potentiostat. As a result of analyzing the potentiodynamic curves, the oxidation-reduction processes were found in weak-acid, neutral and faintly alkaline ranges. Passivation of the gold electrode surface takes place in alkaline solutions. Stationary potentials on the gold electrode in the solutions studied at pH = 11,0, 6,3, and 2,5 were determined. A possibility of electrochemical intensification of the gold dissolution process in the chloride-hypochloric composition was shown.
Casting production
Sidorov E.V., Pikunov M.V. Single-crystal growth out of solid solution alloys
Theoretical and experimental investigations were carried out to produce single-crystals of solid solution alloys subjected to oriented controlled solidification. The main characteristics of alloy crystallization and casting solidification processes are given. The processes providing origination and existence of the two-phase transition region are shown to be necessary for production of monocrystalline castings from alloys with a crystallization interval. The processes and conditions determinant the formation of the flat crystallization front are suitable only for production of single-crystals from the alloys with zero crystallization interval.
Belov M.V., Belov V.D., Ten E.B. On production of ingots from piston hyper-eutectic silumin by semicontinuous casting
Hypereutectic silumins are the most prospective material for manufacturing automotive type pistons not only by chilling but die forging as well. The investigations of the effect of heat treatment modes for samples of hypereutectic silumin Al–16 % Si have shown that a possibility of essential cutting down the homogenization duration of ingots, which serve as work stocks for die forging of pistons.
Korchmit A.V. The effect of casting temperature on structure and properties of copper alloys (review)
A review of the domestic literature on the effect of pouring temperature on formation of the structure and properties of copper alloys is given. The results of mechanical tests of samples made of tin bronzes depending on pouring temperature and casting section thickness are discussed. An interrelation between superheating and distribution of structural components of multicomponent tin bronzes is considered. A pouring temperature rise was found to gives rise to size reduction of eutectoid and tin inclusions in tin bronzes as well as favorably affect their hydraulic strength.
Materials science and heat treatment
Goto Sh., Aso S., Komathsu Y., Belov N.A., Zolotarevsky V.S. Strength of eutectic alloys of the Al–Ce–Ni system
The mechanisms of high-temperature deformation and the dependencies of compressive strength characteristics on the structural parameters of two- and three-phase eutectics of the Al–Ce–Ni system have been studied. The strength of three-phase eutectic (Al) + Al4Ce + Al3Ni is shown to be higher than that of two-phase eutectics (Al) + NiAl3 and (Al) + Al4Ce at all temperatures. The yield stress of the Al–Ce–Ni system eutectics is determined by three components: internal stresses in (Al)-matrix caused by the dislocation density, the Orowan stresses due to interparticle distance and the strength of aluminide particles. At T > 600 K, the strength of the eutectics sharply decreases because of aluminide particle coarsening and decreasing the Young’s moduli of the matrix and aluminides. Within the deformation temperature of 723–873 K, the behavior of all eutectics studied is governed by the Osvald particle growth process.
Powder materials and coatings
Yemelianova T.A., Semyonova A.S. Derivatographic investigation of low-temperature oxidation of powdered metals
The oxidation process of iron and copper powders of 23,0 and 4,5 m m in average diameter of particles respectively was investigated by derivatography. Samples as briquettes with porosity of 25–51 vol. % were heated to T £ 0,32 of metal melting temperature: 250 ° C or 300 ° C for copper and 300 ° C or 500 ° C for iron. The oxidation kinetics during isothermal holding time as well as during slow continuous heating to the temperature specified were investigated. A parabolic dependence of scale lay thickness on isothermal holding time was determined. Several independent experiments fixed an oxidation rate growth when porosity in briquettes increases. The parameters of temperature dependence of oxidation rate constant were determined by the dynamic thermogravimetry. Based on the results of measurement of the specific electrical resistance, a portion of contact surface was calculated in the section of iron briquettes prior and after oxidation – no more than 2 %, proving existence of through porosity and validity of calculations made with the assumption of oxide layer formation on each particle.
Bugakov V.I. Thermal resistance of diamond materials
An analysis of the available data on the effect of compacting pressure (p) on thermal stability of both natural and artificial diamonds was carried out. The temperature of annealing and graphitizing of all diamond types was shown to increase with p value rising. The procedure of studying the effect of compacting pressure on thermal stability of A4, SDB1100, AC125 and ARK4 kind diamond powders is described. A rise in pressure was found to result in slowdown of the diamond graphitizing processes. Particularly this affects the thermal stability of diamonds having inclusions of catalyst metals.
Romanov G.N., Tarasov P.P., Diachkovsky P.K., Savitsky A.P. Dilatometric investigations of liquid-phase reaction sintering of the Al–Cr system
Compacted samples on the basis of Al powder with additive of 2,5–20,0 % (at.) underwent liquid-phase sintering in quartz tube of a dilatometer under the vacuum at 700 ° C. Simultaneously with the temperature variations of the samples during sintering, their dimensions vary in a complex manner because of heat release as a result of alloy-formation. Based on the results of the X-ray phase analysis of sintered alloys, a possible connection of observed volume and temperature variations of compacts with formation of intermediate compounds during liquid-phase sintering was considered.
Structural macrokinetics. Self-propagating high-temperature synthesis
Zozulya V.D. Go-ahead heat-transmission mechanism during thermal explosion of powdered copper-aluminum compacts
Based on the experimental results, which showed the burning front during the thermal explosion of condensed metal-particle systems, a metal-physical model of the go-ahead heat-transmission mechanism for the given process was proposed. Heat transmission by conductivity proceeds towards the temperature gradient successively among the reaction cells uniformly distributed in the mixture volume. Taking the heat transmission of intermetallic layers around the cells as well as the interspaces between them into account, a design scheme to determine the temperature gradient among the cell initially being burnt and the other cells inflammable according to go-ahead mechanism is given. A possibility of occurrence of the burning front can be determined with the help of the temperature gradient.
Heat engineering and environment protection in metallurgy
Arutyunov V.A., Levitsky I.A., Leshinin S.V., Ibadullaev T.B. On one sphere concerned with application of principle of vortex chamber in metallurgy
A new method of afterburning of fuel components in the atmosphere of metallurgical furnaces is described. The method is based on using the principles of a vortex vacuum pump and a flat-flame burner. It is designed as an afterburning device named as a vortex radiation injector (VRI) to be tested under the industrial conditions. A method of raw estimation of the VRI suction capacity was proposed. A mathematical model of gasdynamics of the device is described and some results of mathematical modeling are given.
Process control and automation
Shubladze A.M., Salikhov Z.G., Gulyaev S.V., Shubladze A.A., Salikhov K.Z., Malakhov V.A., Olshvang V.R. High-reliable control of liquid and gas flows by AAAI regulator
Moscow Steel and Alloys Institute jointly with the Trapeznikov Institute of Control Problems and OVEN Production Association (Finland) developed an automatically adjustable adaptive industrial (AAAI) regulator on the basis of which one may create the automatic control systems, which conjoin accuracy and fast response of the classic PID-systems and high reliability and service life of the pulse systems in controlling the process flows of liquid, gases, steam and steam-water mixtures with the help of control elements of the stop valves. The effectiveness of the AAAI-regulator is illustrated with some examples of comparison of its operation and that of the standard automatically adjustable PID-regulator and the pulse regulator. High consumer’s possibilities of the AAAI-regulator compared with TROVIS 6493 regulator manufactured by SAMSON, German Company are shown in their using in one of the processes at the Moscow Oil Refinery.
Chronicle
- Нинель Федоровне Пантелеевой – 80 лет
- Ninel¢ Fyodorovna Panteleeva is 80 years old
