Nonferrous ore concentration

Evdokimov S.I., Panshin A.M. Regularities of contact interaction among particles in polydisperse mineral system
It has been experimentally proved on the model systems that fine fractions adhere mainly to their own coarse ones in the polydispersed mineral system. The flotation tests of lead-zinc ore in the industrial conditions showed that the coarse quarts admixture and pulp mixing with the prescribed intensity promote purification of the sphalerite surface from the slams of the rockforming minerals, the zinc extraction being increased.

Khodzher D.V., Punishko O.A. Prospects and problems of bedding dump processing at gold processing plants
Multiyear dumps of gold processing plants are an alternative basic material source in the content and quantity of gold concentrated in it for gold-mining enterprises. Hard-to-be-extracted gold during prolonged storing of the dumps is broken down under the effect of the natural factors and can be extracted with cyanide process. Investigations have shown that Au extraction reaches 75-82 % during percolation cyanation, and the dumps can be used by their heap leaching. However because of scarce lump size of mineral buildups, the working solution infiltration process through the stock pile size and its holding from static destruction is made difficult. A process has been proposed to palletize the dumps with the use of preliminary drying by warm air or their mixing in predetermined ratios. To prevent ablation, the stock pile height must be less than when ore using and its side walls must be protected by the natural coatings. As a result, the dump processing by heap leaching can be promising practical trend.

Extractive metallurgy of nonferrous metals

Oleinikova N.V., Chekushin V.S., Baksheev S.P. Lead extraction into metallic phase from natural sulfide compounds in alkaline medium
The reduction of lead from galenite of the Gorevsky, Dalnegorsky, and Dukatsky lead concentrates in alkaline medium under the conditions of melting and agitation has been investigated. The formation of lead metal from Dukatsky concentrate is performed at t = 450÷470 °С, from Dalnegorsky one at 500–520 °С, and from Gorevsly one at 600–620 °С. Increase in the alkali : concentrate ratio facilitates somewhat intensification of reduced metal particle coalescence. It was found that the problems of defoaming and coalescence are efficiently sold in the conditions of active mixing of the melt alkali and concentrate mixture. A criterion of hydrodynamic similarity in the process of compact metallized lead phase formation is proposed. Specific alkali consumption was determined in reducing lead from industrial sulfides and it made up 0,42–0,43 g/g.

Vovnova T.M., Orekhova A.I., Khalemsky A.M. Kinetic investigation of sulfuric-acid leaching of Zn-containing waste from NF machining plant
The kinetics of dissolution of Zn-containing waste from the brass production in sulfuric acid has been studied. The dissolution is proved to proceed during two stages. The optimum conditions of zinc sulfate production from the above waste were found. According to the recommendations obtained, commercial zinc vitriol can be produced being in agreement to GOST 8723-82.

Dashkevich R.Ya., Aleksandrov A.V. On resonant behavior of polymorphic transformations α^'_L-β-Ca₂SiO₄ phase transition
The experimental data are given, which show the quenching process in dicalcium silicate to be accompanied by structural process delaying resulting in temperature drop of α^'_L-β-Ca₂SiO₄ phase transition. Nephelinic ore and limestone were used as starting materials. In preparing charging material, the proportion of starting ingredients was calculated for obtaining CaO/SiO₂ = 2,0 mole ratio. A set of portions was prepared from the charging material. All the portions were sintered at t = 1250 °C for 30 min. Then the portions were quenched in the air at t = 750, 650, 550, 450, 350, 250, 150, 25 °C. The content of α^'_L and β-Ca₂SiO₄ in them was determined by quantitative X-ray analysis in DRON-3 spectrometer. The data obtained allow us to propose the resonant behavior of polymorphic transformations in dicalcium silicate.

Kozin V.F., Omelchuk A.A. Formation of complex univalent-copper compounds at Cu⁰–Cu²⁺ phase interface formation of univalent-copper compounds in chloride solutions
The kinetics and mechanism of formation of univalent-copper compounds at the Cu^0-Cu²⁺ interface in the solution containing excess chlorine anions was investigated by spectrophotometry. It is shown that when metallic copper comes in contact with Cu²⁺ ions, complex anions [CuCl₂]^– and [CuCl₃]^2– are formed. The formation of [CuCl₂]^– ions is characterized by appearance of a band at 233 nm in the electronic absorption spectra, and the formation of [CuCl₃]^2– ions by appearance of a band at 273 nm. The Cu²⁺ ions with copper contacting time dependence of the intensity of absorption bands was used to estimate the kinetic parameters of formation and oxidation of [CuCl₂]^– and [CuCl₃]^2– ions. Thickness of the reaction layer, in which anionic complexes of univalent copper are formed, has been determined. The formation of univalent-copper compounds during contact interaction between copper and Cu²⁺ ions has been confirmed by the results of electrochemical investigations. A mechanism of catholic reduction of copper compounds on copper electrode is proposed.

Extractive metallurgy of less-common and precious metals

Kunty O.I., Zozulya G.I., Kurilets O.G. Gold cementation by magnesium in cyanide solutions
The contact gold deposition by magnesium powder in the hydrodynamic regime in 0,001-0,005 M solutions of the [Au(CN)₂]^––CN^– system has been studied. It is established that the gold cementation rate at the early stage is directly proportional to concentration of [Au(CN)₂]^– complex and the cementing agent surface area. In increasing temperature in ranges of 20–30 °C and 30–40 °С, the increments of gold cementation rates are 20–25 % and 8–10 % respectively. The time dependence of degree of gold extraction on magnesium is of extreme nature because of inverse process rate increase, i.e. leaching. Gold cementation rate and extraction degree grow in the ultrasonic field, as caused by destruction of hydroxide layer on magnesium surface. The deposited gold is of filmy in nature.

Naumov A.V. Rhenium rhythms (review of world market)
The current state of the world rhenium market as well as the economics of production and the development trend of rhenium-containing products have been surveyed on the basis of the publications of recent years.

Casting production

Pikunov M.V., Sidorov E.V. On equilibrium crystallization and distribution coefficients of alloy components in the ternary systems with continuous solid and liquid solutions
The features of equilibrium alloy crystallization are discussed in detail for the ternary system consisting of solid and liquid solutions of A, B, and C, the temperatures of which are matched up as t_C < t_А < t_В. The B and C component distribution coefficients are shown to be k_B > 1 and k_C < 1 respectively in the alloys of any composition. Depending on alloy composition, this figure for A component can be more than one or less than one, and we have k_А = 1 at temperature t_A.

Chernomas V.V. Technological characteristics of combined process to produce continuous-cast deformed sections of nonferrous metals
A foundry-forging module is developed and made to produce deformed profiles of predetermined cross section from molten metal in continuous mode. The results of metallographic investigations of continuous-cast deformed sections (CCDS) from technical copper as well as their comparison with the structures of cast test samples are given. Estimation of dimensionally-geometrical accuracy of CCDS samples is given.

Materials science and heat treatment

Denisov V.M., Antonova L.T., Talashmanova Yu.S. Oxidation of liquid tin-silver alloys
The kinetics of Sn–Ag liquid alloy oxidation at T = 1273 К in the air has been investigated. So-called catastrophic oxidation of melts containing 70 and 80 at. % Ag was found. X-ray phase analysis of scale forming on all Sn–Ag alloys as well as under such oxidation has showed that it consists of SnO₂ and silver metal. It is found that the tin dioxide wetting angle by liquid silver is constant and makes up 72,4 ± 4,3 degrees in a range of T = 1234÷1303 К.

Bryantsev P.Yu. Quantitative method of estimating ferrous phase transformation in 6XXX series alloy homogenizing annealing process
A simple quantitative method of estimating ferrous phase transformation in the homogenizing annealing process by particle shape changing is proposed. It was used for analysis of homogenizing annealing extent in dilute alloy 6060 (6063) and optimal isothermal holding mode selection. Feasibility of annealing temperature increasing as high as 600 °С is shown from the analysis results.

Ivanov D.O., Aksenov A.A., Ivanov I.A. Study and modeling of foam aluminum produced from secondary aluminum raw material by mechanical alloying technique
The structure and phase composition of specimens cut from foam aluminum on the basis of AMg6 alloy (Al–6%Mg–0,7%Mn) produced in the high-energy planetary mill have been investigated. Mechanical alloying provides high dispersion ability and homogeneity of all structural components including TiH₂ foam agent particles, permitting production of foam aluminum with pore size of 0,6–5,0 mm and density of 1,20–0,80 g/cm³. The mechanical properties of foam aluminum were estimated from the results of the compression tests. A foam-forming process simulation model, which describes well the process, is proposed on the basis of the preliminary investigations.

Powder materials and coatings

Romanov G.N. “Memory” effect of growth and shrink-off during liquid-phase Al–Cu powder body sintering
Bulk changes of Al–6wt.%Cu powder bodies in the course of liquid-phase sintering have studied by dilatometry. It is shown that the changes that take place during heating can be suspended for indefinitely time period as a result of fast quenching. Exhibition of the “memory” effect of growth and shrink-off in the two-stage liquid-phase Al–Cu powder body sintering process is caused by the diffusion nature of two metals interaction one of which is in the liquid state.

Narva V.K., Shugaev V.A., Vin T. Aluminum powder sintering in the air in the presence of silumin and KAlF₄ flux
KAlF₄ flux role and the effect of its particle size on the PA-4 aluminum powder sintering process have been investigated. Disperse flux is more effective. The model experiments have found the flux flowing regularities over the aluminum surface; it is recommended to use flux with particle size < 50 mm and its total content of 1–3 % in sintering Al-powder with particle size > 60 mm.

Corrosion and metal protection

Belomyttsev M.Yu., Yevseev M.S., Kozlov D.A., Kreitser K.K., Safonov V.V., Chernukha L.G., Shtremel M.A. High-temperature resistance of metal–NiAl based intermetallic compound
High-temperature resistance of NiAl intermetalliс compound, its alloys with Hf and Nb, and composite materials with microcellular structure (tungsten cells with wall thickness of 0,3–3 mm and core of NiAl or NiAl–4at.%Nb alloy) has been investigated. The oxidation rate (w⁺) is calculated by increase in weight in the air at t = 1000÷1300 °С for t ≤ 21 h and the loss rate (w^–) is calculated by loss of weight in removing scale. NiAl and its alloy with 4,4 wt. % Hf has minimum oxidation rate (w⁺ = 4,5÷20 g/(m²·h) at t = 1200 °С). Scale resistance at t = 1000÷1300 °С of NiAl–(13÷44)at.%W(Mo) is well below that that of NiAl intermetallic compound. The higher is the content of refractory metal and porosity, the lower is the scale resistance. It depends very slightly on the method of material composing (cellular structure NiAl–W or mixture of NiAl and W grains of 10–20 mm in size) but short-term heating of the composite with cellular structure (13%W, intermediate layer of 0,5 mm) to 1200–1300 °С (higher that test temperature) can reduce the following oxidation rate by factor of 200 at t = 1000 °С and by factor of 30 at t = 1100 °С.

Process control and automation

Salikhov Z.G., Krivodubsky O.A., Gazimov R.T. Multiposition estimation of the ready strip quality with automatic rolling process control
The principles of solving the urgent task of finishing rolling activity control based on multiposition estimation of the strip quality in each interstand space are given. The proposed method to calculate the estimations is based on using prospective compact laser-optical systems of strip measurement. Strip quality estimate recording separately for every stand allows correcting the control directly in the course of rolling and eliminating shape distortions in case of their arising.

Rutkovsky A.L., Salikhov Z.G., Alekhin V.I. Techniques of derivation of asymptotic theory for optimal control of kinetic processes in processing installations
The article gives an illustration representation of the asymptotic theory of optimal control (OC), a recurrent sequence of the OC systems, which are modified by the Whithem method for the OC systems perturbed in the coordinate of state and perturbed singularly. It is shown that the OC recurrent sequence obtained in this case can be solved simply enough for every its component separately.