Mineral processing of nonferrous metals
Ignatkina V.A. Study of molecular structure of heavy metal ion and diethyldithiocarbamate precipitates
The experimental data are given which are related to the study of the molecular structure of copper, nickel, cobalt, and zinc diethyldithiocarbamate precipitates by IR-spectroscopy and differential scanning calorimetry. A series of Me¾ S bonding strengths of metal ions with DEDTC studied has been found: Ni>Cu>Co>Zn. The molecular structure of the precipitates is shown to affect its processing properties while filtering, floating, and re-extracting out of the froth product. The data of the studies make it possible to qualitatively estimate a possibility of selective extraction of metals out of the precipitates produced in ionic flotation.
Extractive Metallurgy of Nonferrous Metals
Sedykh V.I., Tupitsyn A.A., Bychinsky V.A. Thermodynamic analysis of redox processes with lead as a participant
Using the program complex “Selector-S”, thermodynamic studies found that oxidation of lead sulfide by gaseous oxygen are complex heterogeneous process the features of which are determined by temperature and oxygen content in the system. When oxygen is lacking, metal lead, its mixture with oxide and sulfide are the oxidation products. At “stoichiometric” conditions and the excess oxygen, oxidation of PbS terminates by formation of lead oxide. PbO× PbSO4 and 2PbO× PbSO4 play a significant role in the process of end product formation. Carbon takes no direct part in the redox processes. The presence of CO2 in the gaseous phase shifts the beginning of a series of reactions to lower temperatures.
Begunov A.I., Shevelyova N.N., Kiselyova O.V. Determination of heat related to the interaction of aluminum and gallium with aluminum sulfate solutions
The heats of interaction of aluminum sulfate solutions with the surface of hard gallium and aluminum specimens were measured by microcalometry in a concentration range of 0,001¾ 0,1 mol/l at 299 K. It was found that the specific heat of wetting of the metals studied by aluminum sulfate electrolytic solution is in inverse proportion to the electrolytic solution concentration. When interacting gallium with aluminum sulfate the calorific effect changes from 0,055 down to - 0,032 J/m2, and accordingly for aluminum Q = 0,156¸ 0,072 J/m2. Equations describing the electrolytic concentration dependence of the calorific effect are given in the range studied. The decrease in heat released in wetting aluminum surface and generation of large endothermic effect in wetting gallium depending on the electrolytic solution concentration can be explained by variation of total potential jump during the formation of double electric layer at the cost of its contraction and, as a consequence of the above, by reduction of free surface energy.
Casting Production
Chursin V.M., Gofenshefer L.I. Composition and properties of scale-resistant low copper alloys
The main theoretical conditions for creation of scale-resistant low-temperature copper-based alloys are described. Engineering decisions of synthesizing the alloys have been analyzed on the basis of compiled matrix of alloys using patents published for the last 20 years in the industrialized countries. Own data are given which concern compositions and properties of copper-based low alloys combining simultaneously improved operating and casting properties.
Physical Metallurgy and Heat Treatment
Aksenov A.A., Belov N.A., Medvedeva S.V. Use of Al¾ Si¾ C phase diagram for analysis of phase transformation in composite aluminum-based materials
Systematic studies have been carried out of interaction on the interfaces in composite materials on the basis of aluminum and different aluminum-silicon alloys, which contain silicon carbide particles or fibers. The kind of a hardening element is shown to exercise insignificant influence on the nature of interaction. Produced by different methods, a - and b -modifications of SiC behave practically in like manner in direct contacting the aluminum or aluminum-silicon alloy melts. Using the findings concerning the structure and phase composition of the composite materials after prolonged holding times at 700 ° C, 800 ° C, and 900 ° C as well as the literature data, a more precise definition of the Al¾ Si¾ C diagram has been given including that for non-equilibrium conditions too. Irreversible interactions in the composite materials are shown to be often connected to slowdown or entire suppression of some reactions realized only in the conditions of metastable equilibrium.
Marvina L.A., Marvin V.B., Karibiants V.R., Neupokoeva I.V. On criterion of the stability of grain structure in dispersion-hardened alloys during primary crystallization
A stability criterion of the grain structure in dispersion-hardened alloys (DHA) during primary recrystallization was derived on the basis of equality of the grain boundary and particle velocities in the course of their joint migration and taking the curvature of the grain boundaries among the particles into account. The condition found makes it possible to qualitatively explain known experimental dependences of the grain boundary-particle complex stability on a volumetric portion and sizes of the particles as well as on particle to grain boundary mobility ratio. The last factor is shown to exercise significant influence on the stability of DHA grain structure in moving the particles by the volumetric flow-around mechanism.
Shelekhov E.V., Pripisnov O.N., Rupasov S.I. Analysis of fine crystalline a -Cr structure during mechanical activation of chromium-carbon mixture
The a -Cr crystal latitude unsoundness is estimated after machining of chromium-carbon mixture in centrifugal planetary mill. Duration of mechanical activation was 12 though 43 min, ball to material ratio was 20:1. An improved method of analysis to widen X-ray diffraction lines was applied. The method presupposes the domain profile by ascent to have the value between Cauchy and Gauss functions and can be approximated by their convolution as well as, in addition to homogeneous mean-square microdeformation e , random microdeformation e 1 of separate interplanar distance takes place. It was found that the both linear dimensions of a domain (á Dñ vol, á Dñ area) reduce whereas both microdeformations grow. The fact of random deformation domination is mentioned.
Belov N.A., Matveeva I.A. Computer analysis of Al¾ Fe¾ Si phase diagram as applied to low aluminum alloys
A computer analysis of the Al¾ Fe¾ Si phase diagram in the range of rather small Fe and Si concentrations (<3 %) has been proposed. Based on well-known data, EXCELL patterns were generated to calculate weight and volumetric portions of the phases for preset compositions and annealing temperatures. Using calculated values, polythermal sections were plotted at constant iron and silicon concentrations making it possible to analyze the phase composition of commercial aluminum and low alloying alloys. As examples, the quantitative analysis of the phase composition of semiproducts produced by twin rolling and following treatment and chill castings produced of Al¾ Fe¾ Si alloys is described.
Yegorova Yu.B., Vilkov V.I., Belova S.B. On conditions of titanium alloy hydrogenation in hydrogen technology of metals
On the basis of generalization of published data the expediency of dividing titanium alloys into three groups is shown depending on hydrogen diffusivity. Duration of sufficiently entire hydrogenation of plates and cylindrical samples is estimated for these three groups of alloys.
Barsukov A.D., Khachatryan A.A. To the question on calculations of mixture heat in substitutional solid solutions using lattice spacing data
A precision analysis of lattice spacing for Rh¾ Al, Ir¾ Al, Cu¾ Al, Ni¾ Al, Ag¾ Al, Au¾ Al solid solutions was carried out. A calculation inaccuracy did not exceed 0,05 %. The data obtained made it possible to calculate the mixture heat of above solid solutions with the inaccuracy not exceeding the experimental one.
Powder Materials and Coatings
Yermilov A.G., Safonov V.V., Kolyakin A.V., Doroshko L.F. The effect of preliminary mechanical activation on calorific power of titanium-carbon charge
The effect of different mechanical activation parameters on the reactivity of stoichiometric titanium-carbon charge is estimated. It is shown that heat liberation during reacting the activated charges can exceed the enthalpy of interaction 1,5 times. The energy absorbed in the process of charge machining is ~100 kJ/mole titanium. Heat liberation during heating depends on heating rate of the activated materials up to the component reaction temperature. The stored relaxation parameters during heating are estimated.
Structural Macrokinetics. Self-Propagating High-Temperature Synthesis
Levashov E.A., Malochkin O.V., Kudryashov A.E., Glukhov S.A., Sviridova T.A., Gammel F., Zukhentrung R. On Characteristics of the Effect of Nanocrystalline Powders on Burning Processes and Formation of Composition, Structure, and Properties of SHIM-3B Alloy
A study is made of the effect of different additives of nanocrystalline powders on the macrokinetics of combusting Ti¾ Cr¾ C¾ Ni mixtures as well as on the composition, structure, and physical-mechanical properties of SHIM-3B alloy produced by the power SHS-compaction technique. An additive of nanocrystalline powder is found to result in 2¾ 5-fold modification of aloy structure and, in most cases, in improving physical-mechanical properties (bending strength, hardness, microhardness, and crack growth resistance).
Surface engineering. Multifunction films. Corrosion and metal protection
Kutyrev A.E., Andreev Yu.Ya. Thermodynamic calculation of limited gold enrichment of Ag¾ Au and Cu¾ Au alloys in the course of corrosion
An idea is introduced of limited equilibrium enrichment of gold-bearing alloys by gold that can be achieved during corrosion in order to ground the existence of limiting corrosion resistance of the alloys. A thermodynamic calculation is made of the dependence of limited gold enrichment of Ag, Au- and Cu, Au-alloys on its content inside alloys.
Heat Engineering and Environment Protection in Metallurgy
Sborshchikov G.S. Hydrodynamics and heat-mass exchange in furnaces with bubble layer
Consideration of thermophysical processes in a bubble layer does not make it possible to regard it as incompressible liquid. Taking compressibility of the layer into account the analysis of differential transport equations can reveal two mechanisms of substance transport in it: at the cost of temperature or impurity concentration gradients as well as due to unequal field of velocities and density in the layer volume. Accordingly there are two zones in the layer: a tuyere one (both transport mechanisms operate) and a quasi-stationary layer (with gradientless mechanism the intensity of which depends on the agitating degree of the layer and the gas distribution non-uniformity in it). The tuyere zone structure is examined at different blowing modes through the submerged side tuyere. Semiempirical and empirical formulas are given to calculate outflow parameters and elements of layer structure as well as dimensionless coefficients of interphase exchange.
Miroshkina L.A., Koblova N.S., Klimov M.A. Study of the effect of multicomponent pollution of the atmosphere (air environment) on the health of children’s garden at Zheleznodorozhny town, Moscow Province
An ecological and hygienic estimate of the atmosphere over Zheleznodorozhny town was made. The data concerning pollutant emissions out of industrial enterprises and motor transport are the calculating basis of the surface detrimental substances according to OND-86 procedure. The results of calculations were used as starting data for a model describing the dependence of the disease incidence related to children breathing organs on the environmental condition. The precision of the model results and actual disease levels made it possible to forecast changing the disease incidences while expanding the extent of the industrial production and the designing new enterprises.
Grechko A.V. Extracts from the history of furnaces: theory, practice, prospects
Historical stages of furnace development in different technical fields and creation of furnace theory beginning from Lomonosov’s proceedings and including the works of great scientists Grum¾ Grzhimailo and Glinkov are shortly considered. Considerations related to further development of general theory of furnaces on the eve of XXI century are stated.
Process Control and Automation
Kimyaev I.T., Salikhov Z.G., Spesivtsev A.V., Drozdov A.V. Study of supercritical domains of factorial space in controlling calcination in a gas-fluidized bed with the help of fuzzy control model
Nonlinearity resides in multivariate (multiple-factor) processes, which practically the whole metallurgical ones concern to. The technological instructions regulate carrying out the process for every factor (variable), i.e. in a linear form. Nevertheless as well known from the practice, a combination of factors even in acceptable limits can result in the emergency condition of a process. Identification of such combinations is possible in the nonlinear control model [1] developed with the use of fuzzy sets.
Danilin E.N., Salikhov Z.G., Khodov N.V. Mathematical model of low-temperature alkaline lead-concentrate melting process
A mathematical model of a new prospecting low-temperature alkaline lead-concentrate melting process, which can be used for decision of the actual problem related to the synthesis of the automatic control system for this process, is developed. Adequacy of the model developed is shown on the basis of comparative analysis of experimental data and data produced with the help of mathematical modeling.
