Extractive metallurgy of nonferrous metals
Vostrikov V.A., Vostrikova N.M. Study of the process to utilize vapor-gas sulfur-containing mixtures with producing elemental sulfur
The condensation process of vapor-gas mixture with approximately equal vapor content (~99 % vol.) was investigated at different temperatures with and without the air present. The roasting process was studied in effervescing gas composition, quantity of elemental sulfur produced during condensation, content of acidic gas component as well as time dependences. It was found that sulfur disengages in elemental form and arsenic does in the form of sulfides of different stoichiometry during condensation of vapor-gas sulfur-containing mixtures. The results obtained afford ground for designing the process flow diagrams and the devices for utilization of sulfur-containing gases from pyrometallurgical processes by non-catalytic methods on the basis of directed regulation of H2S and SO2 contents in the gases.
Begunov A.I., Yakovlev S.A., Yakovleva A.A. Kinetic regularities of magnesium dissolving in acidic media
The kinetic mechanisms of magnesium dissolving with using its metal powder of MPF-3 grade were investigated. Acidic and acid-salt systems: H2SO4 (0–2,90 M), MgSO4 (0–2,96 M), HCl (0–1,25 M), and MgCl2 (0–3,20 M) solutions served as solvents. The experiments were carried out at the room temperature. The quantitative characteristics of the process being investigated were obtained. Increasing the concentration of any solvent was shown to raise the apparent dissolving constant (k) of magnesium metal. It was found that it dissolves more actively in hydrochloric media: in particular, k value is practically greater by an order of magnitude in the saturated solution of MgCl2 (1,08∙10- 1 h- 1) than in the saturated solution of MgSO4 (2,23∙10- 2 h- 1).
Golovnykh N.V., Bychinsky V.A., Tupitsyn A.A., Shepelev I.I. Optimization of process flow diagrams for fluoride salt recycling under the conditions of present-day aluminum production
Allowing providing the recycling of the main mass of sludge, up-to-date approaches to the solution of the problems related to utilization of waste from production of fluoric salts are considered. In modernizing the aluminum production, the correction of the process flow sheet was shown to be necessary to reduce amount of solid waste. It is reasonable to process the gas cleaning solutions producing low-modulus cryolite (chiolite) with the help of ion-exchange filters while removing sulfates as sulfuric acid solution. The given version of “acidic” flow chart may be realized under the conditions of conventional soda reflux without acidification of the gas cleaning solutions – with using “own” fluorine only. Implementation of the “dry” anode technique in electrolyzers with top current feedthrough results in reducing the volumes of coal-froth flotation tailings 1,5–2,0 times as well as gas cleaning dusts and sludge. Flotation selection of finely dispersed particles with the help of downgoing sludge-air flow in column apparatuses facilitates increasing the cryolite output and decreasing by 7–10 % the waste coming to the sludge fields. The technological measures allow us to significantly raise the efficiency and competitiveness of the existing gas cleaning systems during electrolysis of aluminum.
Extractive metallurgy of less-common and precious metals
Naumov A.V. Review of the world market of selenium and tellurium. Economy of selenium and tellurium
A review of the present-day state of the world and Russian markets of selenium and tellurium is given based on the publications of the recent years.
Elyutin A.V., Medvedev I.A., Nikitin A.E. High-purity tantalum production by zinc-thermal reduction of its pentachloride
The article presents the results of a thermodynamic study concerned with the possible reactions of reduction of tantalum chlorides by zinc metal. Material of the reduction reactor has been selected. Complex compound KTaCl6 with KCl in plenty was proposed for using as initial material for reduction. The design of the installation is given and the two-stage reduction process of KTaCl6 by liquid and then gaseous zinc followed by vacuum separation of the reduction products is described. High-purity tantalum with the content of metal impurities: K, Zn, Al, Fe, Si, Ca, and W ≤ 10 ppm each, Nb = 10÷20 ppm, O2 0,2 % wt. was produced as a result of separation. The direct extraction of tantalum metal reaches 94,5 % during the zinc-thermal reduction from its pentachloride.
Strizhko L.S., Zakharova V.I., Bezrukova Zh.N. Extraction of silver from diluted solution by biosorbents
Sorption capacity of various kinds of waste from the production of healthcare products was investigated with respect to silver. Producent biomasses of lincomycin, gentamycin, neomycin, ristomycin (produced at AO “Ferein”, Moscow), and fusidyn, erythromycin, levorin, and penicillin (AO “Biosynthesis”, Penza city) were used. In studying the behavior of microbial biomass in neutral and acidic environments, it was found that they affect the solution pH and lose weight during processing. Being greatest for producents of levorin, neomycin, and gentamycin, the biomass capacity by silver was investigated. The effect of environment pH, temperature, and duration of the process on biosorption of silver was studied. The dependence of exchange capacity of biomasses on equilibrium metal concentration, the regularities of silver sorption by biosorbents under the dynamic conditions as well as its desorption with biomasses were investigated.
Sokolova Yu.V., Cherepanin R.N., Sagalova T.B. Synthesis and some properties of potassium fluoroscandates
Interaction of scandium chloride solution with crystalline potassium hydrodifluoride in the range of molecular ratios F : Sc from 2 to 12 was studied. X-ray phase, X-ray spectral, differential thermal, and thermal gravimetric analyses were used for investigation of the properties of the compounds produced. Their solubility was studied.
Kozin V.F., Omelchuk A.A. Kinetics and mechanism of monovalent indium ion formation in the system of In0- In2(SO4)3- In2SO4
Using optical and spectrophotometric analysis, the kinetics and mechanism of lowest-oxidation-degree indium formation were investigated and equilibrium concentrations in the system In0–In2(SO4)3–In2SO4 were determined. The stability of In+ ions in sulfuric solutions was found to be dependant on the content of trivalent indium, temperature, and solution acidity. It was shown that compound In2SO4, being characterized by occurrence a band in the range of 210 nm on the spectra of electronic absorption, is formed in the contact of indium metal with In3+ ions. The dependence of its intensity on In3+ ion contact time with indium metal was used for determination of the kinetic indices of In+ formation. The results obtained can be useful for estimation of the parameters of indium production and electrochemical refining.
Rubtsov Yu.I. Use of solid solutions of silver sulfates in anglesite during “dry” sulfatation
The regularities of formation of badly soluble solid solutions of silver sulfate in anglesite during sulfatation of sulfide concentrates by sulfuric acid were theoretically substantiated and experimentally studied. The flow schemes of simple and complex sulfatation of arsenic-containing materials were developed. The schemes permit producing iron-arsenic-containing product and commercial concentrates – leaded product with solid solution of silver sulfate in anglesite and lean tin-containing product. Throughout recovery of the main components is 92–98 %. Arsenic-containing solutions are neutralized to ecologically nonhazardous product or realized after completion as toxic pigment.
Rubtsov Yu.I. Procedure of the system approach to metal dissolution kinetics
The experimental technique to determine the maximum rate of dissolution of metals was developed. The technique was supported by the theoretical concepts on the kinetics taking the secondary interactions into account when the Gibbs diagram was used as a concentration coordinate for the reagents. It was theoretically substantiated that the metal dissolution rate in the heterogeneous system of water–reagents–metal with isomolar concentration of reagents passes through the maximum. The efficiency of the given proposition was proved by the laboratory investigations and pilot tests related to extraction of gold and accompanying metals from mineral raw materials.
Materials science and heat treatment
Belov N.A., Alabin A.N., Istomin-Kastrovsky V.V., Stepanova E.G. The effect of annealing on structure and mechanical properties of cold-rolled sheets of Al- Zn-alloys
The effect of annealing conditions on the structure and mechanical properties of cold-rolled sheets from aluminum-zirconium alloys containing as much as 0,6 % wt. Zr was studied. It was shown that the mechanical hardening may be retained and additionally hardness and ultimate strength may be improved at the zirconium concentration ≥ 0,4 % and application of step-wise annealing as high as T = 450 ° C. Addition of 0,2 % Zr and heating to T > 300 ° C result in strong softening. The positive effect of increased zirconium concentration is caused by formation of secondary precipitations of metastable phase Al3Zr (< 10 nm in size) during annealing, which not only suppress recrystallization process but facilitate additional precipitation hardening.
Powder materials and coatings
Putintseva M.N. Study of complex tungsten-cobalt carbide formation during solid alloy dispersion
The reasons of formation of complex tungsten-cobalt carbides and intermetallic compounds were studied depending on the conditions and dispersion medium as well as on Co and Ti contents in the initial alloys. It was found that the dispersion of WC–Co in hydrocarbons is accompanied by formation of tungsten-cobalt complex carbide of h 1-phase. Dispersion in water can result in formation of h 2- and c -phases and Co7W6 intermetallic compound. Occurrence of CoTi intermetallic compound was representative for the powders of WC–TiC–Co composition.
Vostrikov V.A., Vostrikova N.M. The effect of pulse current supply on iron powder size during electrolysis of melt
An opportunity of reducing the powder size at the cost of pulse current supply in the course of electrolysis was found. The current interruption for 2–5 s after time limit for 1 min under current facilitates reducing the yield of unconditioned powder fraction (+0,4 mm) from 6,2–8,6 to 2,0–3,3 %. The particle size grows when the electrolysis time increases and the number of cycles decreases. Small powder forms particles of irregular shape (needles, sheet-like crystals), which fracture as a result of hydrometallurgical processing.
Surface engineering. Multifunctional films. Corrosion and metal protection
Gulevsky S.A., Yemelina N.B., Petelin A.L. Liquid-metal penetration of bismuth along grain boundaries and triple junctions in copper
An original technique is considered for studying the processes of liquid-metal moistening along the grain boundaries and triple junctions. The technique has a number of essential advantages in analyzing the penetration of liquid phase along the triple junctions. It is shown qualitatively that a portion of the moistened grain boundaries as well as the triple junctions drops with the depth. The light microscopy found out that the penetration depth of bismuth along the triple junctions is greater in the mean than that along the grain boundaries.
Chronicle
- Michail Iosifovich Alkatsev is 80 years old
- Vladimir Aleksandrovich Arutyunov is 70 years old
- Boris Petrovich Burylev
