Nonferrous ore concentration
Melik-Gaikazyan V.I., Yemelianov V.M., Yemelianova N.P., Moiseev A.A., Yemelianov V.V., Yushina T.I. To investigation of foam floatation process and selection of reagents on the basis of the mechanism of their action. Report 2. Part one. To comparison of floatation properties of milli-, micro-, and nanometer bubbles on the basis of equations of capillary physics
Using equations of capillary physics, the calculation shows the capillary pressure in bubbles from 3 mm to 5 nm in diameter changes from thousandth fractions to several hundreds of atmospheres and affects the processes concerned with foam flotation. Bubbles of 2 µm in diameter can spontaneously (i.e. with energy loss) adhere to solid surface, and this trend grows adiabatically with decrease of their size. This is the main thing. The reality of such a mechanism has been supported by the longstanding practice of application of the Potter-Delpra process. In view of the above, in investigating the flotation process, it is reasonable to use the equation of capillary physics and not to be oriented to the principle of the "effective collisions" of particles and bubbles as a necessary condition of their adhesion and flotation. This is more efficient.
Key words: equations of capillary physics, effective collisions, spontaneous adherence, microbubbles, wetting quality, flotation, coalescence.
Goryachev B.E., Nikolayev A.A. Thermodynamics of chromate-ion interaction with mineral complex of polymetallic ores: Galenite
Thermodynamic studies of the PbS–H2O–O2–CO2–C4H9OCSS––CrO4 2– system and potentiometric measurements of galena electrode potential in alkaline solutions of potassium bichromate and potassium butyl xanthate have been carried out. As a result of the analysis of feasible summary semireactions of interaction of galena with chromate and xanthate ions in alkaline media with taking different oxidation rate of sulfide sulfur of galena into account, new dependencies are found. It is established that the bond between the concentrations of chromate and xanthate ions, when their interaction with the galena surface is thermodynamically probable, does not depend on the oxidation rate of sulfide sulfur in mineral to S0, S2O3 2–, SO4 2–. The dependence of electrochemical potential on pH and concentration of chromate and xanthate ions in liquid phase is determined. The obtained results show the potential-determining character of the effect both of chromate and hydroxide ions on galena.
Key words: thermodynamic system, galena, chromate ions, potential-determining ions, alkaline medium, electrochemical potential of semireaction, galena electrode potential, selective flotation of lead-copper concentrates.
Extractive metallurgy of nonferrous metals
Komkov V.G., Gostishchev V.V., Ri E.Kh., Dorofeev S.V.The effect of nanosecond electromagnetic impulses on production of tin and properties of its alloys
It is experimentally established that the impact of nanosecond electromagnetic impulses (NEMI) on melt mixture in carbothermic reduction process of tinstone concentrate in the Na2CO3–NaNO3 (1:0.3) environment at 900–950 °C accelerates formation of metal phase ~ 2 times and affects its composition. Thus if the duration of irradiation increases to 30 min, tin content in draught alloy raises to ~ 95 %. The effect of NEMI processing of melt bronze on its physical-mechanical properties is found out. The effect of NEMI on melt bronze within 10–15 min is shown to raise the alloy density to 8,92 g/cm3, hardness 1,24 times, heat conductivity 2 times.
Key words: nanosecond electromagnetic impulses, tin production, melt processing, bronze properties.
Volkovich A.V., Trofimov I.S., Zhuravlev V.I. Anode behavior of zinc, cadmium, and their alloys with barium in chloride and oxide-chloride melts
Anode polarization of zinc, cadmium, and their alloys with barium has been investigated in chloride and oxide-chloride Ba-containing electrolytes. Barium dissolution from alloys is accompanied by concentration polarization on the part of metal phase and proceeds selectively. The electrocapillary effect on anode polarization both of metal zinc and cadmium, and their alloys with barium is shown. Diffusion layer thickness in Ba–Zn and Ba–Cd alloys is calculated. In polarizing zinc, cadmium, and their alloys with barium in oxide-chloride melt, the sections concerning the limit speed of diffusive mass transfer of dissolved ВаO to the metal anode surface appear on the curves.
Key words: anode polarization, zinc, cadmium, chloride and oxide-chloride melts, barium oxide, limiting diffusive current density, diffusion layer thickness, electrocapillary effects.
Minaev E.S., Vertman A.A., Burtsev V.T., Minaev Yu.A. Thermodynamics of burned dolomite reduction
Thermodynamic data have been measured and evaluations of Gibbs energy (DG 0) change standard values have been carried out for three groups (selected of 32) of silicon reduction reactions of burned dolomite distinguishing by oxygen contents in reduced products and being characteristic for the processes with restricted access of oxygen (retort method), vacuum silicon reduction with and without carbon addition. It is found that the burned dolomite reduction reactions to Fe2SiO4, Ca2SiO4, and CaMg (SiO3)2 in the retort method, presented in the classical works, have positive or negative value DG 0 close to zero and hence they are practically improbable. Reactions followed by formation of complex Ca3Mg (SiO4)2 calcium-magnesium silicate are thermodynamically more preferable. Negative absolute DG 0 value is 4–8 times more for vacuum silicon reduction with and without introduction of carbon with formation of Ca2SiO4 at temperatures of 1200–1350 K. Optimum temperature and kinetic parameters of the processes are experimentally found. The use of carbon as an additional reducing agent speeds stably Mg output by 20–30 %. Thus FeSi is diminishes 3 times as compared with the retort method and 2 times as against the vacuum process without carbon. The obtained data were a basis for the project specifications of the installation design for vacuum silicon reduction of magnesium from burned dolomites.
Key words: silicon reduction of Mg, dolomite, retort method, thermodynamic performances, calcium-magnesium silicates, ferrosilicon.
Baranov A.N., Morenko A.V., Gavrilenko L.V., Gavrilenko A.A. Resource saving technology of aluminum electrolytic furnace bottom salt slag processing
The results of studying salt slags from the aluminum electrolytic furnace bottom under the conditions of running electrolysis production are given. The mechanism of their formation, chemical composition and some properties are considered. The potential worth of this type of secondary raw materials for the electrolysis production is shown as well as the necessity of searching effective ways of their processing is indicated. Some alternatives that allow involving salt slags in the production with minimum losses are proposed. Laboratory and pilot tests on the proposed ways have been carried out and expected technological and ecological effects have been calculated.
Key words: bottom salt slags, overhaul of electrolytic furnaces, waste processing, standard secondary raw materials.
Vasyunina N.V., Vasyunina I.P., Mikhalev Yu.G., Polyakov P.V. Aluminum solubility in alumina-cryolite electrolytes
The complex effect of aluminum, calcium, lithium, and potassium fluoride additives on the total aluminum solubility in alumina-cryolite melt has been investigated. The investigations were conducted at constant overheat of the alumina saturated melt (15 °C relative to liquidus temperature). Aluminum solubility was determined by long metal holding in the melt at specified temperature followed by taking a sample that was quickly frozen, and aluminum content in it was measured gas-volumetrically. In decreasing cryolite ratio (CR) from 2,5 to 2,2, the aluminum solubility in electrolyte is reduced 1,7 times but subsequent CR decreasing to 2,1 results in no substantial aluminum solubility variation. Introduction of 3 wt.% LiF and 5 wt.% KF into the melt at constant overheat considerably decreases aluminum solubility 2,9 and 1,5 times respectively.
Key words: aluminum solubility, alumina-cryolite electrolytes, cell efficiency, current output.
Extractive metallurgy of less-common and precious metals
Zhuravlev V.I., Redkin S.A. Study of sorption properties of pyrazole-containing resins in relation to platinum-group metals
The results of investigations on improving the reactive indexes of pyrazole-containing sorbents for palladium and platinum extraction out of their acid solutions are given. For these purposes, SVPD grade sorbent having the microporous structure on the basis of N-vinil-3(5)-methyl-pyrazole and divinyl benzene has been synthesized and tested. Its reactive performances by palladium and platinum are determined. Using various acidities of the initial solutions, comparative tests of SVPD resin with SDP-grade pyrazole-containing sorbent of macroporous structure produced on the base of styrene-divinylbenzene and 3(5)-under deprotonating additive have been carried out. The advantage of SVPD grade sorbent by its reactive parameters as against macroporous SDP-d one is shown. The optimum acidities of initial solutions are found in extracting palladium and platinum by the sorbents. Two samples of bifunctional resins the structure of which contains groups of N-vinyl-3(5)-methyl-pyrazole and organic sulfides have been synthesized. The results of their tests have shown that introduction of organic sulfides in the structure of resin results not only in improving the reactivity of the sorbent by palladium but also considerably expands a working acidity range of the solutions.
Key words: acid solutions, palladium, platinum, sorbent, N-vinyl-3(5)-methyl-pyrazole, styrene, divinyl benzene, acidity of solutions.
Verbovenko I.M., Rychkov V.N., Kartashov V.V. Kinetics of aluminum, zirconium, and hafnium sorption over KM 2P carboxylic cation exchange resin
The aluminum, zirconium, and hafnium ion interchanging kinetics over KM 2P in Na+ form carboxylic cation exchange resin are given as experimental and design data produced in investigation by the bath method. The effect of grain size of ion exchanger, agitation speed, and temperature on the sorption process rate is shown. It is established that the system limiting stage is the pore diffusion. The interdiffusion coefficients and apparent activation energy values of the process are calculated.
Key words: ion exchange, carboxylic cation exchange resins, zirconium, hafnium, aluminum.
Materials science and heat treatment
Kotelkin A.V., Zvonkov A.D., Lyutsau A.V., Matveev D.B., Tikhonov V.S., Nurgaleev A.R. The effect of nanodimensional strengthening phase on the behavior of 1953T1 aluminum alloy at cyclic load
The article contains the results of behavior fatigue correlation investigation (number of cycles N to fracture) and level of surface residual stresses (s) of cyclic deformation of specimens made of high-strength aluminum alloy with nanodimensional strengthening phase used for manufacture of drill pipes. The tests were carried out at zero-to-tension stress cycle with maximum value of tensile load of 160 MPa. To determine the s level, portable X-ray diffractometer DRP-RIKOR was used. As a result, essential increase of fatigue resistance (increase in number of cycles to fracture) was found in the presence of initial compressing surface residual stresses of order –120–200 MPa (0,25–0,4 of alloy yield strength). The dependence s(N) has non-monotone character that can be caused to irregularity of local plastic deformation near dispersed intermetallic precipitations. At the same time, in case of local cyclic character the specified dependence tends to the increment that is expressed by means of a linear function thus allowing us to evaluate and forecast fracture by the level of surface residual stresses.
Key words: cyclic fatigue, residual stresses, X-ray diffraction analysis, aluminum alloys, Pearson correlation coefficient.
Metal forming
Agapitova O.Yu., Byvaltsev S.V., Zalazinsky A.G. Improvement of hydromechanical extrusion process of nonferrous metal
Mathematical simulation of the hydromechanical extrusion process of color and difficult-to-form metals through two sequentially fitted cone dies has been carried out. The process is accompanied by active friction forces that allowed us to reduce considerably extruding forces. The optimum parameters of the tool for minimization of extruding forces are determined. A program complex integrated with SolidWorks and DEFORM packages and intended for solving the problems of plastic deformation of metals and designing an optimum construction of extrusion tools has been developed for computer simulation in the MATLAB system.
Key words: hydromechanical extrusion, simulation, optimum construction, MATLAB, SolidWorks, DEFORM.
Powder materials and coatings
Blinkov I.V., Volkhonsky A.O., Kuznetsov D.V. Physical-mechanical and operational properties of nanostructural wear-resisting ion-plasma vacuum-arc coatings on the basis of multi-component nitrides
The work is devoted to investigation of hardness (H), elastic modulus (E), and adhesion/cohesive strength of ion-plasma vacuum-arc coatings of the Ti–Cr–Al–N system. It is shown that H and E values are determined by crystallite sizes and microdeformation level. The maximum hardness (as high as 32 GPa) and elastic modulus (as high as 700 GPa) are according to the coatings with minimum crystallite size and maximum microdeformation. Wear-and-tear of produced coatings is accompanied by cohesion failure. Adhesion strength of coatings is evaluated by the values of 90 N. The stability of cutting cemented-carbide tools with designed coatings increases 5,1 and 5,7 times respectively in operations of continuous and interrupted cutting of 38KhNMA steel.
Key words: ionic-plasma electric arc deposition, coatings, crystallite size, microdeformations, hardness, elastic modulus, adhesion-cohesive failure of coatings, tool durability.
Process control and automation
Novokreshchenov S.A., Shvydky V.S., Zhukov V.P., Cheremisin D.D., Kholod S.I. Mathematic simulation of bubble flow hydrodynamics during bottom blowing of furnace ladle. Report 1
The results of mathematic simulation of changes in geometrical sizes of a gas bubble in its moving to the melt surface during fire refining of copper in a ladle furnace are given. The effect of temperature field and hydrostatic pressure on the bubble sizes is evaluated. As a result, the essential change in gas bubble volume allows us to suggest that its movement to the melt surface is of unsteady nature.
Key words: mathematic simulation, hydrodynamics, gas bubble, temperature field, ladle furnace, melt.
