I. N. Tanutrov, S. A. Lyamkin, M. N. Sviridova.

ABSTRACT

  Pyrometallurgical technology of obtaining of germanium concentrates of lignits deposits (coal, shales, siltstones) accompanied with the receipt of molten silicate slags. The mineral composition of the raw material is concentrated in the slags, reaching 60% by weight. It is obvious that the energy performance of technology is largely determined by the physical and chemical properties of slag melts. These include specific electrical conductivity (λ), reflecting the structure of silicate melts. Slag compositions from the processing of carbonaceous raw materials differ significantly from those of non-ferrous and ferrous metallurgy: they contain increased amounts of SiO2 (up to 50–55%), Al₂O₃ (up to 20–22%), as well as K₂O and Na₂O (up to 5–6%). In addition, the slag contains significant amounts of sulfide sulfur (up to 3%) and trace amounts of non-ferrous metals and rare elements (up to 5%). Differences in the composition of slag melts of germanium production from the slag of the main metallurgy affect their properties and require special research. Objects were the industrial designs cyclone and electromelting slags. The method of semi-synthetic samples obtained from industrial by adding SiO₂ and CaO was used to determine the effect of the composition on λ. For measurements, a standard compensation method for measuring the active resistance of the melt by an AC bridge with a frequency of 3.5 kHz was used. Cell served the investigated melt in Al₂O₃ crucible with submerged double molybdenum electrode. The interval of temperature measurements in the melt was in the range of 1250–1550°С. As a result of the measurements, it was found that the values of λ of melts are in the range from 0.01 to 0.30 Cm/cm and significantly depend on the basicity (the ratio of the sum of CaO and MgO co-holdings to SiO₂), as well as the content of Al2O3. It is found that the temperature dependence of λ is exponential. In General, λ of the studied melts is much higher than typical ones, for example, for blast furnace smelting with equal basicity. The results are useful for predicting melt structure and utilization.

KEYWORDS:

germanium concentrates, pyrometallurgy, slag melts, specific electrical conductivity

DOI:10.31857/S0235010620020127

V. V. Chebykin, V. M. Ivenko, L. A. Tsiovkina.

ABSTRACT

  From tensimetric data (38 compositions from 0.09 to 99.0 mol. % Cs) of Cs–CsCl melts, approximating equations were obtained for the cesium activity coefficients in specific experiments, as well as a general equation describing all experimental points. The conditions of the experiment and their influence on the error of the experimental data are discussed.

KEYWORDS:

melts, solutions, activity coefficients, cesium, cesium chloride

DOI:10.31857/S0235010620020036

A. A. Khokhryakov, A. S. Paivin, М. А. Samoylova.

ABSTRACT

  This article is devoted to investigation of optical spectra of molten systems MeF–YbF₃ (M =Li, Na, K, Cs). It was found from spectral data that complex groupings YbF₆^3- were formed. The formation of grouping YbF₆^4- was discovered in melt LiF–YbF₃ causes from partly restorative atmosphere in stove-unit. It was assumed that sharp jump of wave number corresponding to electronic transition ²F_7/2 → Г₈²F_5/2 Yb(III) from LiF, NaF melts to KF, CsF ones caused by decrease of second coordination number from 14 to 13.

KEYWORDS:

micro-inhomogeneity, micro-heterogeneity, structural transformations, overheating, aluminum alloys

DOI:10.31857/S0235010620020073

V. M. Ivenko, V. Yu. Shishkin.

ABSTRACT

  The solubility of silver in liquid potassium was measured at temperatures of 500, 600, 700, and 930°C. At each temperature, an experiment was performed with three parallels. The average solubility for each temperature is 0.59, 1.41, 2.88, and 8.67 mol. % Ag respectively.

KEYWORDS:

melts, solubility, silver, solubility coefficient, potassium

DOI:10.31857/S023501062002005X

O. E. Pukhova, S. D. Levchenko.

ABSTRACT

The results of pyrometallurgical refining of platinum-rhodium alloys from contaminants during induction remelting under the influence of oxygen are presented. The results of atomic emission, atomic absorption and X-ray fluorescence analyses are presented. The kinetic features of the reactions between the components in the purification process are considered. The effect of the dispersion of the refining powder on the rate of reactions is investigated.

KEYWORDS:

refining, platinum metals, impurities

DOI:10.31857/S0235010620020115

Yu. G. Pastukhov.

ABSTRACT

  It is proposed to use the electrochemical Peltier heat of the anode dissolution reaction for thermal calibration of the estance of the studied metal electrode. A change in the electrode potential leads to a gradual transition from a double-layer process of charging and adsorption to the region of a reversible electrode. The use of thermal estance data for gold in the CsCl melt made it possible to estimate the value of the Peltier and Seebeck coefficients for this half-reaction.

KEYWORDS:

Peltier electrochemical heat, Seebeck coefficient, surface tension of a solid electrode, piezoacoustic response during potential modulation, molten alkali metal halides, gold, anodic dissolution, halogen evolution, thermal estance

DOI:10.31857/S0235010620020139

D. A. Vetrova, S. A. Kuznetsov.

ABSTRACT

  The charge transfer kinetic for the redox couple Ti(IV)/Ti(III) in the KCl–KF(10 wt. %)–K₂TiF₆ was studied. The standard rate constants of charge transfer (k_s) for the redox couple Ti(IV)/Ti(III) in the KCl–KF(10 wt. %)–K₂TiF₆ melt and the activation energies of charge transfer were calculated. Influence of strongly polarizing cations on the charge transfer kinetics was studied. It was determined the linear dependence of k_s on ionic potential of alkali earth metal cation. The activation energies of charge transfer in case of strongly polarizing cations addition were calculated.

KEYWORDS:

melt, redox couple, titanium complexes, quasi-reversible process, cyclic voltammetry, standard rate constants of charge transfer

DOI:10.31857/S0235010620300015

A. Yu. Nikolaev, A. V. Suzdaltsev, Yu. P. Zaikov.

ABSTRACT

  Kinetics of the aluminum and scandium electrodeposition from the oxide-fluoride and fluoride melts was studied by mean of voltammetry. The parameters (potential range, currents) of aluminum and scandium electrodeposition from the fluoride melts with the additions of Al₂O₃, Sc₂O₃, AlF₃, and ScF₃ in the temperature range of 750–800°С were defined. A novel approach has been proposed to produce the Al–Sc master alloys enriched with scandium, including the electrodeposition of aluminum and scandium on a solid cathode during the electrolysis of oxide-fluoride or fluoride melts and the subsequent dissolution of the obtained cathode sediment in liquid aluminum. On the basis of electrochemical measurements, the parameters of stable electrolysis of the melts under study were chosen and electrolysis tests were carried out to produce Al-Sc master alloys. The cathode current efficiencies during the co-electrodeposition of aluminum and scandium were estimated, and the microstructure of the obtained Al–Sc master alloys was studied.

KEYWORDS:

aluminium, scandium, melt, voltammetry, electrowinning, electrodeposition, electrolysis, master alloy

DOI:10.31857/S0235010620020097

A. V. Kaibichev, I. A. Kaibichev. 

ABSTRACT

  The interelectrode transport of silver, the atomic mass and the number of atoms in ions are calculated from experimental transfers, changes in the electric field strength and the fraction of ions in electricity. The change in atomic masses and the number of Ag, Mo atoms in ions in the period of removal from the molybdenum electrode was determined. The difference between the interelectrode and experimental transfers was established for the negative and positive polarity of the silver melt. The conditions for the purification of silver from impurities in a direct current electric field are substantiated.

KEYWORDS:

melt, evaporation, electricity, polarity, atom, ion, electron

DOI: 10.31857/S0235010620020061

O. V. Gusakova, V. G. Shepelevich, D. V. Alexandrov, I. O. Starodumov.

ABSTRACT

  Studies of the microstructure, phase composition, component distribution, and grain structure of industrial technical eutectic silumin with composition Al–12.2Si–0.2Fe (at. %) obtained at cooling rates of 102 and 105 K/s. At both cooling rates, the alloys are characterized by three phases: α-aluminum, silicon, and iron-containing phase. Massive samples are characterized by a heterogeneous dendritic structure representing large dendrites of a solid solution based on aluminum, and a eutectic lamellar mixture of aluminum and silicon filling the interdendritic spacing. The rapidly solidified foils are characterized by a uniform microstructure, however, they have a thickness layering. The rapidly solidified foils are also distinguished by the homogeneity of the grain structure in thickness and the absence of any pronounced texture. The mechanisms of solidification and the formation of a microstructure are proposed, both for massive samples and for rapidly solidified foils.

KEYWORDS:

silumin, eutectic, microstructure, rapid solidification

DOI:10.31857/S0235010620020048