REC Mekhanobr Tekhnika

Russia

REC Mekhanobr Tekhnika

Russia
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Vaisberg L.A.,REC Mekhanobr Tekhnika | Kuskova Y.V.,Saint Petersburg Mining University
Obogashchenie Rud | Year: 2017

Gravity concentration takes the lead among other mineral processing methods. One of the frequently enough used gravity concentration processes is beneficiation on concentrating tables. Concentrating tables are used for beneficiation of small-size fractions of tin, tungsten, rare and noble metals ores, as well as other minerals. In these apparatuses pulp is moving upon inclined surface under action of gravity with low-depth water flow. A fairly large number of designs of concentrating tables are known, in particular, with circular-shaped decks. At different times, the leading specialists in gravity concentration participated in developmental studies with regard to circular concentrating tables. A considerable amount of the accomplished research and development work permitted to solve such problems as increased precision of materials separation into products, improved beneficiation process parameters, development of new designs of concentrating tables. The results of the newly-designed circular concentrating tables testing are described in this paper. A test rig has been designed and produced at the ≪Mekhanobr≫ Institute that includes a damped elastically-mounted superresonance vibration stand with bi-harmonic drive creating swinging oscillations, removable decks and a number of auxiliary units. In the course of the investigations, a number of drawbacks of the concentrating table design deficiencies were revealed, that later were eliminated during the testing and technological works. New designs of circular concentrating tables were developed and tested. The tests results proved a sufficiently high performance and efficiency of the concentrating tables in question. On the basis of these tests, improved designs of circular concentrating tables were developed over the last ten years, providing for increased minerals separation efficiency.


Blekhman I.I.,Russian Academy of Sciences | Blekhman L.I.,REC Mekhanobr Tekhnika | Yaroshevich N.P.,Lutsk National Technical University
Obogashchenie Rud | Year: 2017

Drive oscillations of vibratory machines with inertial unbalance vibration exciter are considered in this paper. In this type of machines electric motor shaft is connected with exciter shaft through an element that allows relative shafts offset (elastic coupling, V-belt transmission, cardan shaft). This connection of shafts is specific for vibratory screens, conveyors, feeders and other machines with electric motor installed on immovable foundation and exciter shaft - upon machine vibrating body. It is shown that presence of the shafts connection in question introduces significant specifics into machine drive dynamics. Body of vibratory machine with inertia excitation is usually supported by cushioned antivibration mounts. With that, natural frequencies of machine body on supports are several times lower, than operating frequency of body vibrations. As a result, during start-up and running-out system attains a condition of resonance, followed by violent vibrations, and, sometimes, with insufficient motor power, rotational frequency crawling in the vicinity of relevant natural frequency (Sommerfeld's effect). These special aspects must be taken into consideration in machines design, in order to avoid a condition of hazardous vibrations both in start-up and steady state operation. The study was performed on the basis of vibrational mechanics approach and direct motion separation method. The theoretical results are compared with the computerized simulation results.


Kazakov S.V.,REC Mekhanobr Tekhnika | Shishkin E.V.,National Mining University
Obogashchenie Rud | Year: 2015

Taking into consideration severization of requirements to vibratory machines with respect to throughput rate, reliability and compact design, their improvement becomes increasingly important and difficult task. One of the promising ways to improve vibratory machines is changeover from one-mass and two-mass machines to machines based on three-mass system. A vibratory cone crusher based on two-mass system is distinguished by a number of advantages in comparison with one-mass machines. With that, it suffers from one significant deficiency: during operation impact loads are bound to recur, producing an extremely detrimental effect upon machine's elements that are non-functioning directly in impact, in particular, on vibration exciters and their bearings. Creation of vibro-impact crusher based on three-mass system will permit to considerably decrease dynamic loads on bearings of vibration exciters' rotors owing to so-termed vibration damping effect, that may almost completely isolate crusher's foundation from unbalanced dynamic forces. In order to improve mechanical and performance parameters of vibratory cone crusher, a design model of machine based on three-mass system is proposed. Crusher's body and cone vertical-plane oscillations are generated by a pair of inertial vibration exciters, installed on vibrating platform, which, in turn is supported on immovable foundation through vibration isolators of low stiffness. Differential equations of crusher's motion, describing vertical-axis free-oscillation modes of crusher's body and cone, as well as vibrating platform, are derived. Solution of these equations permitted to establish the expressions for machine's natural frequencies and free-oscillation modes, analysis of which provides for assessment of its forced oscillation mode, specifically: to determine resonance frequencies and ratios of body and cone oscillation amplitudes to that of vibrating platform.


Shishkin E.V.,National Mining University | Kazakov S.V.,REC Mekhanobr Tekhnika
Obogashchenie Rud | Year: 2015

Vibratory cone crusher, developed by the Research-and-Production Group «Mekhanobr-Tekhnika» for disintegration of different hard materials, is characterized by such advantages as a high reduction ratio and low content of small size fractions in crushed product. The article considers the dynamics of vibratory cone crusher that comprises body with inner crushing cone, attached to it by means of a special resilient member. Cone possesses only single translational degree-of-freedom relative to body, and with that, crusher is driven from a pair of self-synchronizing vibration exciters, attached to machine body symmetrically about its vertical axis. In addition to that, crusher's dynamic model is symmetrical and balanced, with body and cone performing in operating regime purely vertical opposite-phase oscillations of the same frequency. Besides, viscous interaction force is assumed to act between body and cone with coefficient β. The value of this coefficient may be selected through experimental determination of energy losses over crusher's synchronous oscillations period. In this case, the dynamic model under consideration may be also tentatively used for analysis of vibro-impact operating mode. In order to verify the results of the theoretical studies of vibratory cone crusher's dynamics, the experimental studies were performed, and the theoretical results agreed with the experimental ones with sufficient degree of accuracy. In addition to that, on the basis of the performed studies a conclusion may be drawn, that in the system in question a regime is possible, when body and cone perform synchronous opposite-phase oscillations (crusher's operating mode). A possibility for realization of required regime of body and cone oscillations will considerably improve operational parameters of crushers, designed according to the described configuration.


Arsentyev V.A.,REC Mekhanobr Tekhnika | Gerasimov A.M.,REC Mekhanobr Tekhnika | Mezenin A.O.,REC Mekhanobr Tekhnika
Obogashchenie Rud | Year: 2017

The paper presents the results of the Troshkovskoye deposit kaoline ore dressability study with application of hydrothermal modification for the purpose of kaoline concentrate subsequent chemical-and-metallurgical processing with a view to alumina production. It is shown, that provision of a high-performance kaolines processing technology requires modification of starting kaoline feed structure, thus providing for mineral product with particles that are characterized by a lower ability, if compared with starting kaoline feed, for interacting with each other and with dispersion medium. An approximate comparative technical and economical evaluation of two technologies has been accomplished: the conventional wet gravity technology, developed at the «Mekhanobr» Institute, and the proposed technology that includes kaoline feed processing in autoclave with subsequent wet sizing. As a result of the study, it was established, that high-silica kaoline ores are a promising raw material for alumina production. Kaoline feed hydrothermal modification in autoclave leads to a considerable decrease in kaoline slurry viscosity and facilitates subsequent efficient beneficiation. The developed process flow diagram of high-silica kaoline raw material wet processing permits to produce kaoline concentrate with Al2O3 mass fraction of 30.1 %, recovery being 91.1 %, suitable for chemical-and-metallurgical conversion to alumina.


Dmitriev S.V.,REC Mekhanobr Tekhnika | Stepanyan A.S.,REC Mekhanobr Tekhnika
Obogashchenie Rud | Year: 2017

At the present time, only a certain part of electronics scrap characterized by an appreciable value owing to precious metals content, becomes subject to salvaging. It accounts for only 15 % of the total electronics scrap volume. The remaining 85 % is thrown on the scrap-heap. Taking into consideration the increasing negative impact of electronics scrap upon environment, there is a pressing need for development and introduction of salvaging methods that would render economically sound recycling of time-expired electronics with low content of precious metals. In spite of substantial number of research, performed in recent years, and commercial availability of offers with respect to technologies and equipment for recycling of electronics scrap, they fail to take into account the changes made in modern electronics, and, consequently, changes in material composition of electronic scrap, and more specifically, decreasing content of valuable elements. Alongside this, electronics miniaturization caused a limitation in application of physical-mechanical methods that constitute a basis of the existing technologies for electronics scrap recycling. At the present day, both in mineral processing, and electronics scrap recycling, electrical separation methods are widely applied, based on strong electric field effect upon charged solid particles. It is the authors' opinion that methods and devices for electrical separation with combined action of different factors upon separated material attract the most interest. A new design of this type of separator has been developed at the Research and Engineering Corporation «Mekhanobr-Tekhnika».


Aminov V.N.,Petrozavodsk State University | Kameneva E.E.,Petrozavodsk State University | Ustinov I.D.,REC Mekhanobr Tekhnika
Obogashchenie Rud | Year: 2017

The primary objective of rocks physico-mechanical properties studies with a view to use rock materials for construction purposes is to determine their applicability in principle for crushed stone production. For this purpose, a number of rocks physical parameters are determined: Strength, water absorption capacity, porosity, harmful components and impurities content, and others. If these parameters comply with the specified requirements, crushed stone size fraction 10-20 mm, obtained by crushing under the laboratory conditions, is subjected to testing. The test parameters are strength, abrasion strength, freezethaw resistance, bulk density and mineral density, water absorption capacity. As a rule, laboratory jaw crushers DSCH 60x100 or DSCH 100×200 are used for rocks geological samples crushing, providing for feed lump size within 50 and 90 mm, respectively, and producing required product size for subsequent tests. A high flakiness of crushed stone produced under laboratory conditions leads to underestimated values in main strength characteristics. In order to eliminate variances in size-fraction composition of crushed stone produced in conventional laboratory jaw crushers and crushed stone material produced on a commercial basis, a new laboratory jaw crusher 2 SCHDS 100×200, developed at the Research-and-Engineering Corporation ≪Mekhanobr-Tekhnika≫, is proposed for application. This jaw crusher working organs are two jaws kinematically interlocked in synchronous operation, performing complex reciprocating and elliptical motion. This character of jaws motion provides for application of shearing and compressive forces to crushed material, resulting in product crushed stone with low fraction of flaky grains. This crushed product is in the main of cubic shape, possessing a granulometric characteristic close to product parameters of commercial-scale crushers, thus permitting to correctly compare physical properties of crushed stone produced commercially and under the laboratory conditions.


Blekhman I.I.,Russian Academy of Sciences | Blekhman L.I.,Russian Academy of Sciences | Vaisberg L.A.,REC Mekhanobr tekhnika | Ivanov K.S.,Russian Academy of Sciences
Vibroengineering Procedia | Year: 2014

This talk presents two approaches for modeling of the vibration screening process. The first approach is analytical. It models the screening process as a diffusion of undersize fraction taking into account the special term for vibration separation (the Brazil nut effect). The talk provides a solution of the corresponding partial differential equation. The solution in turn allows estimation of the screening performance dependence on both deterministic and stochastic factors as well as evaluation of the factors dominance conditions. The talk presents simple evaluation formulae for the screening process performance. The second approach is based on a simulation model. The model deals with monolayer dynamics. Embodying traditional concepts of vibration transportation, the approach introduces some novel techniques of evaluation of the effect of the granular particles shape. Taking into account the particle shape factor may significantly improve the modeling precision for nonspherical particles. © JVE INTERNATIONAL LTD.


Kazakov S.V.,REC Mekhanobr Tekhnika | Shishkin E.V.,Saint Petersburg Mining University
Obogashchenie Rud | Year: 2016

A symmetrical flat dynamic design of vibratory cone crusher based on three-mass system is considered. It includes carrying body (vibrating platform) with two working organs (body and cone). Crusher's body and cone are linked with each other through elastic system with coefficient of stiffness Cp, cone and vibrating platform - Through elastic system with coefficient of stiffness n. Vibrating platform is supported by immovable foundation via resilient shock absorbers of negligible stiffness. Oscillations in the system under consideration are excited by a pair of self-synchronizing inertial vibration exciters, installed not on one of the working organs, as in conventional dynamic design of vibratory cone crusher, but on carrying body. The laws of pure forced oscillations of working organs and carrying body were revealed, and their amplitudefrequency characteristics were plotted, permitting to determine crusher's optimum operating mode. This operating mode is provided with working organs' exact antiphase oscillations at same oscillation frequency. Besides, it is shown, that at a certain disturbing frequency, carrying body becomes stationary (antiresonance), and only working organs vibrate. The latter together with elastic system n form so- Termed dynamic absorber of carrying body. Owing to vibration absorbing effect, dynamical loads on vibration exciters' bearings in the machine in question may be significantly decreased, also including impact loads. Moreover, application of this effect will permit to almost completely isolate foundation from unbalanced dynamic forces. A method of approximate estimate is proposed with respect to equivalent viscous resistance coefficient permitting to take into consideration effect of crushed material upon crusher's dynamics. The considered dynamic design of vibratory cone crusher seems to be promising for application in vibratory machines, designed for disintegration of various hard materials.


Arsentyev V.A.,REC Mekhanobr Tekhnika | Vaysberg L.A.,REC Mekhanobr Tekhnika | Ustinov I.D.,REC Mekhanobr Tekhnika
Obogashchenie Rud | Year: 2014

Scientific pre-requirements for development of promising dry and low-water-consumption technologies for finely ground mineral materials processing have been considered. Such technologies and equipment for their realization may be based on application of vibratory effects, in particular, on the effect of separated material vibrational fluidization. In vibrational fluidization state, particles move relative to one another with partial loss of contact. With that, particles detach from one another with thorough mixing. Dry separation of powder-particles smaller than 0.5 mm by their mechanical-and-physical properties is possible in the following processing operations: size classification; separation of particles according to magnetic properties; separation of particles according to electrical properties. In addition to that, subjecting of flotation slurry to vibrational effects opens the way to development of vibratory flotation machines, operating with slurries of significantly higher density, than slurries in conventional mechanical-air and pneumatic flotation machines. This in its turn creates prerequisites for drastic cuts in process water consumption in flotation - the most mass-scale process used for non-ferrous metal ores benefication. © 2014 John Wiley & Sons, Ltd.

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