Establishing the effect of a simultaneous reduction in the filling load inside a chamber and in the content of the crushed material on the energy intensity of self-oscillatory grinding in a tumbling mill

Deineka, Kateryna; Naumenko, Yuriy

doi:10.15587/1729-4061.2021.224948

Cited by 5 publications

(11 citation statements)

References 19 publications

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“…In the mutual transition of the continuous modes of circulation motion and the wall layer, the periodic self-oscillating mode may occur [4][5][6][7]. If the chamber speed increases, instability of the continuous circulation mode develops, which leads to periodic self-oscillations of the filler [8] (Fig.…”

Section: Results Of the Study Of The Qualitative Nature Of The Motion...mentioning

confidence: 99%

“…5. The values of ψ ωbif were determined by expression (7). The graphs of changes in the increase in the extreme value of filler dilatancy Δυ ext depending on κ lf for κ ff = 0 and 1 are shown in Fig.…”

Section: Results Of the Study Of Quantitative Conditions Of Self-exci...mentioning

confidence: 99%

“…1. Sequential images of the self-oscillating motion of the laboratory ball mill filler for one oscillation period [3] In [4][5][6][7], the effectiveness of the innovative self-oscillating grinding process in a drum mill was evaluated. Quantitative estimation of the dynamic parameters of the filler impact action and the energy and technological parameters of grinding for one value of the filling degree of the chamber was carried out in [4].…”

Section: Introductionmentioning

confidence: 99%

“…The effect of the material content on the motion modes of grinding bodies and the efficiency of self-oscillating grinding for one value of the chamber filler was studied in [6]. In [7], the influence of a simultaneous change in the chamber filling degree and ground material content on the grinding process was studied. However, conditions for self-oscillations of the rotating drum granular filler remain unclear.…”

Section: Introductionmentioning

confidence: 99%

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Revealing the mechanism of stability loss of a two-fraction granular flow in a rotating drum

Deineka

Naumenko

2022

EEJET

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The qualitative nature and quantitative parameters of motion instability of a two-fraction granular filler of a rotating drum were determined. The factors of motion instability and key parameters of the oscillating system were identified and their influence on the self-excitation of pulsed self-oscillations was estimated. Two continuous and one periodic steady-state modes of filler motion were found. Periodic self-oscillations due to the development of instability during the transition from continuous circulation mode to the wall layer mode were revealed. As factors of motion instability, filler dilatancy and damping effect of fine fraction particles on the pulsed interaction of coarse fraction particles were taken. It turned out that the main key parameter of the oscillating system is the drum speed, which determines a change in dilatancy. The increase in instability is realized as a reduction of the bifurcation values of speed and dilatancy. Other key parameters are the content of the fine fraction in the filler κff and the filling degree of the chamber κlf, the growth of which increases the self-oscillating instability. The features of the oscillatory system are the relaxation type, discontinuous nature of self-oscillations and hard self-excitation mode under bistability. The discontinuous character and oscillatory hysteresis increase with decreasing κff and κlf. The limit values of the dynamic motion parameters corresponding to the conditions of self-excitation of self-oscillations in the absence and presence of fine fraction were determined: 0.96–1.11 and 0.218–0.382 for the bifurcation value of relative speed, 0.745–0.855 and 0.24–0.322 for the bifurcation value of dilatancy. The effects found make it possible to substantiate the parameters of the self-oscillating process of processing polygranular materials in drum-type machines.

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Section: Results Of the Study Of The Qualitative Nature Of The Motion...mentioning

confidence: 99%

Section: Results Of the Study Of Quantitative Conditions Of Self-exci...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Revealing the mechanism of stability loss of a two-fraction granular flow in a rotating drum

Deineka

Naumenko

2022

EEJET

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“…The energy efficiency of such a process increases with a decrease in the degree of filling the chamber [6] and the content of the crushed material in the load [7]. Specific energy consumption sharply decreases with a joint decrease in the filling of the chamber and the content of the material [8].…”

Section: Introductionmentioning

confidence: 99%

The effect of the filling degree of the tumbling mill chamber on the bifurcation value of the froude number

Deineka¹,

Naumenko²,

Myronenko³

2021

TT: PhE

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The influence of the filling degree of the drum chamber on the bifurcation value of the Froude number in the case of self-excitation of self-oscillations of a two-fraction granular charge with a minimum swing is considered. Such a pulsating mode of the charge movement is used in the self-oscillating grinding process in a tumbling mill. The coarse fraction that simulated the milling bodies consisted of spherical particles of an incoherent granular material with a relative size in the chamber ψb=0.00733. The fine fraction, simulating the material to be ground, was cement with a relative particle size ψm≈0.092∙10-3. The value of the adopted analogue of the kinematic viscosity of the two-fraction granular loading approached the value of 10-3 m2/s. The main variable factor in experimental studies was the filling degree of the drum chamber with loading at rest κb=0.25, 0.35, and 0.45. An additional factor was the degree of filling the gaps between the spherical particles of the coarse fraction with particles of the fine fraction κb=0, 0.25, 0.5, and 1. The method of visual analysis through the transparent end wall of the chamber of transient processes of the loading behavior with a smooth change and fixation of the velocity was applied. The bifurcation minimum value of the rotation speed was recorded, at which the steady-state circulation mode of the load movement turns into a transient pulsation one with a minimum swing. A decrease in the bifurcation values of the Froude number Frb on the cylindrical surface of the chamber with an increase in κb has been established. An increase in the intensity of the decrease in Frb with an increase in κm was revealed. The recorded effect is due to an increase in the connected properties of a two-fraction loading during self-excitation of self-excited oscillations with an increase in κb and κm. The numerical values of the boundaries of the range of bifurcation values of the Froude number for a tumbling mill Frb=0.0484–1.17 have been determined. The obtained Frb range corresponds to the Reynolds value in the range Re=40–197. The maximum Frb value is obtained with coarse grinding. An increase in the likelihood of self-excitation of self-oscillations of the intra-chamber loading with a decrease in the fineness of grinding was revealed

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Building a model of the impact grinding mechanism in a tumbling mill based on data visualization

Naumenko

Deineka

2023

EEJET

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A mathematical model was built based on data visualization for the impact grinding mechanism in a tumbling mill, which is mainly implemented during coarse grinding. The determination of impulse interaction parameters is problematic due to the difficulty of modeling and the complexity of hardware analysis of the behavior of intramill loading. Conceptually, it was envisaged to identify the relative dynamic parameters of the impact action as components of the model, which are criteria for the similarity of the loading movement and the grinding process. Impact power was taken as an analog of grinding performance. The initial characteristic of the impact was considered to be the averaged vertical component of the speed of loading movement in the flight zone at the boundary of contact with the shear layer. The formalization of the model revealed the effect on the performance of the mass fraction of the flight zone and the reversibility of loading. The method of numerical modeling was applied, based on experimental visualization of the behavior of granular loading in the cross section of a rotating chamber. The influence of the rotation speed on the performance at a chamber filling degree of 0.45 and a relative particle size of a milling load of 0.0104 was estimated by experimental simulation. The maximum productivity value was found at the relative speed of rotation ψω=1–1.05. A rational condition for impact grinding at ψω=0.75–0.9 has been established. The test proved the effectiveness of using visualization to evaluate dynamic loading interaction analogs. Verification of modeling results was implemented by comparison with the data of the technical standard. The use of similarity criteria unifies approaches to modeling different mechanisms of destruction. The model built makes it possible to predict the rational parameters of the grinding processes by impact, crushing, and abrasion

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Establishing the effect of a simultaneous reduction in the filling load inside a chamber and in the content of the crushed material on the energy intensity of self-oscillatory grinding in a tumbling mill

Cited by 5 publications

References 19 publications

Revealing the mechanism of stability loss of a two-fraction granular flow in a rotating drum

Revealing the mechanism of stability loss of a two-fraction granular flow in a rotating drum

The effect of the filling degree of the tumbling mill chamber on the bifurcation value of the froude number

Building a model of the impact grinding mechanism in a tumbling mill based on data visualization

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