Chemical And Metallurgical Institute Named After Zh Abishev

Kazakhstan

Chemical And Metallurgical Institute Named After Zh Abishev

Kazakhstan
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Malyshev V.P.,Chemical And Metallurgical Institute Named After Zh Abishev | Makasheva A.M.,Chemical And Metallurgical Institute Named After Zh Abishev | Zubrina Yu.S.,Chemical And Metallurgical Institute Named After Zh Abishev
Obogashchenie Rud | Year: 2017

A comparative analysis of grinding process in ball and rod mills was performed on the basis of the probabilistic model of grinding. The analysis showed that rod mills are preferred for grinding of coarser size fractions. The reason for this is their advantage with respect to steric (spatial-orientation) factor. With respect to rod grinding, this factor is greater than that of ball grinding in total size range of grains, owing to smaller shielding effect by rod for grains, rather than that provided by ball. Activation (disintegration) factor of rod grinding also exceeds that of ball grinding, although somewhat to a smaller degree, but very strongly with respect to coarse size fractions. Combined effect of steric and activation factors leads to formation of maximums in the range of mm size fractions. This maximum is significantly higher with respect to rod grinding, than for ball grinding. For this reason, coarse size fractions rod grinding process theoretically is much more efficient, than that of ball grinding, which in practical operation results in lower electric power consumption. The calculations showed, that with rod grinding, distribution of size fractions becomes more uniform, which is also in good agreement with the practical operation data. With rod grinding, just as with ball grinding, logarithmically normal distribution is formed in the course of grinding process, which is related to applicability of integrated model of grinding to any variants of sequential disintegration of material. The obtained probabilistic model of rod grinding, taking into account all acting factors, may be considered most complete and ready for practical application.


Malyshev V.P.,Chemical And Metallurgical Institute Named After Zh Abishev | Makasheva A.M.,Chemical And Metallurgical Institute Named After Zh Abishev | Bekturganov N.S.,National Scientific Technological Holding Parasat | Tokbulatov T.Y.,Kazakhmys Corporation | And 2 more authors.
Obogashchenie Rud | Year: 2014

In elaboration of the probabilistic model of grinding, proposed by the authors, the new probabilistic model application for commercial mills adjustment to actual operation conditions on the basis of direct comparison of actual and calculated particle size fractions distribution of mill product is shown. The work was performed together with the staff of Chemical-metallurgical Institute (Karaganda), AO «NNT Holding Parasat» (Astana), TOO «Kazakhmys Corporation» (Zhezkazgan) and the Karaganda State University named after Ye. A. Buketov. The measurements were performed by the personnel of the Zhezkazgan Concentrating Plant 1. Hard ore from an underground mine, blended with up to 40-45 % of «Zhomart» open pit ore with hardness similar to that of Zhezkazgan ore, was processed. 3.2×3.1 MShR grate discharge mill operated in primary grinding stage in locked circuit with KCH spiral classifier. On the whole, it may be stated, that in spite of numerous disturbances in operating conditions, the probabilistic model of grinding represents grinding process realization adequately and objectively, and may be used as a performance management tool for this most complex process, and the described sequence of this model adaptation may be employed as a technique for commercial mills Computer Modeled parameter processing. Correlation of theoretical and actual data on particle size fractions distribution may be used, if required, for correction of mill operating parameters. With that, a seeming complexity of theoretical calculations may be easily overcome through their programming for computer processing within the framework of Automatic Process Control systems, available in modern production.


Pavlovich M.V.,Chemical And Metallurgical Institute Named After Zh Abishev | Sultanovich B.N.,Academician of National Academy of science of the Republic of Kazakhstan | Mundukovna T.A.,Chemical And Metallurgical Institute Named After Zh Abishev | Asanovich K.D.,Karaganda State University
Obogashchenie Rud | Year: 2013

The probabilistic model of grinding, developed by the authors, analyses the effect of balls' sizes and their mixture upon ore grinding. With that, an explanation is given to certain features, earlier known only through the practical data. If small balls are used, product size-fractional makeup is characterized by appearance of two analytical maximums in coarse and small fractions areas, providing a theoretical basis for sep- aration of these fractions in mill's operation in locked cycle with classifier. If balls' mixture is used, grinding process rate becomes higher, if compared with mono-fractional balls of the same total mass, indicating a synergistic effect in their mutual impact upon the process. Position of logarithmic-normal maximum, in contrast to separate application of different size balls, is shifted in time towards small fractions' area, and is accompanied by passage through greatest absolute magnitude of maximum, which is higher, than any current magnitude of maximum with separate application of the same sizes of balls. This maximum is formed earlier, if compared with separate application of balls of different sizes, not at the very end of the studied interval (3600 s), which is also a highly favorable factor. Absolute magnitude of maximum fractions yield is higher for balls' mixture, when compared with separate application of balls of different sizes, with shift towards finer fractions' area, providing a basis for a preferred application of different size balls' mixtures. It is noted, that in the considered modeled conditions with respect to a sufficiently coarse quarts ore mono fraction (0.01 m) grinding, all processes of fine product fractions yield become time-shifted towards greater process duration. If finer fraction is subjected to grinding, especially, if it simultaneously contains middle and fine size fractions, time intervals should essentially decrease.


Pavlovich M.V.,Chemical And Metallurgical Institute Named After Zh Abishev | Mundukovna T.A.,Chemical And Metallurgical Institute Named After Zh Abishev | Asanovich K.D.,Karaganda State University
Obogashchenie Rud | Year: 2013

The probabilistic model of grinding, developed by the authors, permits to consider wet grinding process in a drum ball mill in tumbling regime, and, on this basis, to recommend a more general expression for process rate constant. Consideration of diluting action of water with respect to volume fraction of balls and ore grains mixed with water may be expressed through additional consideration of water mass and density. With that, integral model of grinding remains unchanged. All calculations of water content diluting action in mixture with grinding balls and ore grains are given by way of example of commercial ball mill operation. Besides it is defined, that a common specialty with respect to dry and wet grinding is position of rate constant maximum. With increase in balls and ore grains mixture plasticity and their grinding-in during lift to circular cycle top point, in free fall of this mixture on impact area, effect of smoothing influence of water will not be produced, as falling velocities of all mixture components are practically equal, and in this case closeness of contacts between balls and grains will be dominating, being entirely dependent on water disagglutinating action-diluter in this peculiar suspension. In connection with new calculations, it becomes important to consider wet grinding with use of mixture of balls of different sizes, and also with stage grinding in locked circuit with classifiers.


Malyshev V.P.,Chemical And Metallurgical Institute Named After Zh Abishev | Makasheva A.M.,Chemical And Metallurgical Institute Named After Zh Abishev | Zubrina Yu.S.,Chemical And Metallurgical Institute Named After Zh Abishev
Obogashchenie Rud | Year: 2016

The purpose of the study consists in substantiation of a possibility for direct simulation of laboratory and commercial mills operation. In the context of the probabilistic theory of grinding it was established that, because with mill diameter increase collision frequency decreases, and grains breaking increases, scaling factor of grinding rate is determined by counter effect of mill diameter on required collision frequency of balls and grains and upon grains breaking with impact. As a result, extremal dependence of grinding rate constant on mill diameter is formed, permitting to substantiate the maximum identity with respect to grinding rate of laboratory and commercial mills of certain size. It was established that, laboratory mills of smaller diameter simulate operation of larger diameter commercial mills better, owing to equality of frequency and activation factors product with regard to them. Maximum identity with respect to grinding rate falls on batch-laboratory and commercial mills of 1.8-1.9 m in diameter. Stricter correspondence of operational results of both types of mills may be established by additionally taking into account the starting fractional makeup of grinding bodies and ground mill feed material. In the general case, direct calculation of current fractional makeup of ground mill feed material is expedient by means of immediate probabilistic model of grinding with respect to commercial mill's operational conditions.


Pavlovich M.V.,Chemical And Metallurgical Institute Named After Zh Abishev | Mundukovna T.A.,Chemical And Metallurgical Institute Named After Zh Abishev
Obogashchenie Rud | Year: 2013

The probabilistic model of grinding elaborated by the authors, based on similarity to the theory of molecular collisions for irreversible successive reactions with unlimited stages, is applicable in analyzing the grinding process in the context of concepts used in chemistry and physics to describe energy of activation, half-life, entropy of mixing and dissipative structures in cases of non-linear deviation from equilibrium and selforganization. The energy of activation of disintegration of grains with balls determined through a constant value of the speed of grinding of the coarsest (primary) size based on one or several test runs, may thereafter be used to calculate for other sizes, as well as to provide case-by-case description of grinding resistance in comparing it for different materials. More direct parameters of grindability may offered by the so-called half-time period, determined through a constant of the process speed for a specific size range and providing an indication of the length of half-time disintegration of the feed beginning at any point in time. Entropy of mixing of sizes produced in grinding overtime is characterized by steady reduction down to the limits in line with formation of lognormal size distribution by content. It shows the emergence of self-organization processes in a chaotic mechanical system of balls and grains in a cyclic motion and exposure of grains to the energy of impacts of balls, under the effect of resistance forces of the activation and steric (spacial) factors.


Oskembekov I.M.,Chemical And Metallurgical Institute Named After Zh Abishev | Katkeeva G.L.,Chemical And Metallurgical Institute Named After Zh Abishev
Obogashchenie Rud | Year: 2014

The results of the studies, performed with a view to develop a technology for heat-and-power facilities' bottom ash waste treatment, are presented. The experiments on ash sintering with ammonium bifluoride and ammonium sulphate were performed on the basis of probabilisticand-deterministic approach in order to achieve coal ash breakdown. A mathematical model of sintering was obtained, by means of which the process optimal conditions were determined. Possible production of high-grade silicon oxide from coal ash is described. The effects of sintering factors: temperature, time and liberating reagents consumption were studied. Analysis of partial dependences showed, that in matrix experiments silica recovery degree is mostly affected by sintering process duration and ammonium bifluoride consumption. So, silica recovery is increased by 27 % on the average with sintering duration increase from 30 to 180 min, and ammonium bifluoride consumption - from 50 to 150 %. As a result, a silica product - silicon oxide is produced, its chemical composition complying with the requirements for high-grade silica white. The proposed treatment technology will permit not only to enhance the raw material base for silica production, but also significantly improve the environmental situation in the region. © 2014 John Wiley & Sons, Ltd.


Malyshev V.P.,Chemical And Metallurgical Institute Named After Zh Abishev | Makasheva A.M.,Chemical And Metallurgical Institute Named After Zh Abishev | Zubrina Y.S.,Chemical And Metallurgical Institute Named After Zh Abishev
Obogashchenie Rud | Year: 2016

The purpose of the work is to provide theoretical justification for more efficient and less costly process of ore grinding. The probabilistic theory of material grinding in ball mills is used for this purpose. In accordance with this theory, grinding process is affected by four probabilistic factors: frequency, concentration, steric and activation. In this paper the authors reveal the antagonism of the two latter factors and their coeffect is estimated. The antagonism of steric and activation factors is considered for different combinations of balls and grains sizes, as well as with mill diameter variations. In this respect it has been established, that on the strength of steric and activation factors' antagonism, most efficient grinding is achieved with balls and grains sizes ratio of 20 : 1, which was corroborated by the practical data. With that, maximum efficiency is equal to the value of 0.134 (13.4 %), this demonstrates the existence of the upper limit of energy efficiency of grinding, which has never been overcome in practice. As far as mill diameter is concerned, its increase leads to a certain increase in maximum of grinding efficiency. This is achieved through activation factor, but only up to a diameter of about 7 m, with further increase in diameter, increase in maximum of grinding efficiency slows down. The obtained results provide evidence of productivity of probabilistic theory of grinding and expediency of its further development.

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