Establishing the effect of decreased power intensity of self-oscillatory grinding in a tumbling mill when the crushed material content in the intra-chamber fill is reduced

Abstract

The influence of the content of crushed material in the intra-chamber grinding fill on the efficiency of the self-oscillatory grinding process in the tumbling mill was assessed. A dynamic effect of a significant decrease in self-oscillatory action of the two-fraction fill of the rotary chamber with an increase in the content of fine fraction was revealed by the method of visual analysis of motion patterns. A decrease in values of the following inertial fill parameters was established: maximum dilatancy υ max , the relative amplitude of self-oscillations ψ Rυ and a maximum share of the active part κ fam max with an increase in the degree of filling the gaps between particles of the coarse fraction κ mbgr. A decrease in the generalized complex degree of dynamic activation K a was also established. The effect is due to the strengthening of the cohesive properties of the incoherent coarse fraction under the influence of the fine fraction. There was a decrease in by 29 % for υ max, by 7 % for ψ Rυ , 2.9 times for κ fam max and 4.2 times for K a with an increase in κ mbgr from 0 to 1 at the degree of filling the chamber with the fill κ br = 0.45. Technological effect of a significant decrease in specific energy intensity and an increase in productivity of the innovative self-oscillatory grinding process in comparison with characteristics of the conventional steady-state process at a decrease in the content of crushed material in the fill was established. A process of milling cement clinker with grinding bo dies at relative size of 0.026 and κ br = 0.45 was considered. A decrease in specific energy intensity by 27 % at κ mbgr = 1, by 38 % at κ mbgr = 0.5625 and by 44 % at κ mbgr = 0 was found. An increase in relative productivity by 7 % at κ mbgr = 1, by 26 % at κ mbgr = 0.5625 and by 39 % at κ mbgr = 0.125 was established. The established effects will make it possible to forecast rational parameters of the self-oscillatory grinding process in a tumbling mill at the variation of the content of the crushed material in the fill Keywords: tumbling mill, content of crushed material in intra-chamber fill, self-oscillations, energy intensity of grinding

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

“…The effect of varying κ mbgr = 0.125-1 on the modes of movement of grinding bodies and the effectiveness of self-oscillatory grinding for one discrete value κ br = 0.45 was studied in [5]. The decrease in such inertial load parameters as maxi mum dilatancy υ max , the relative scope of self-oscillations ψ Rυ , the maximum share of the active part of κ fammax , and the generalized integrated degree of dynamic activation K a was detected with the growth of κ mbgr .…”

“…Works [4,5] showed that with a decrease in the value of one of the factors κ br and κ mbgr , the values of the dynamic and inertial parameters and characteristics of the self-oscillatory motion of load are increased. These parameters include the maximum load dilatancy over one pulsation period υ max , the relative scale of self-oscillations ψ Rυ , and the maximum mass fraction of the active load part κ fammax .…”

“…Papers [3][4][5] demonstrated that as the value of one of the factors κ br and κ mbgr decreases, the relative process performance value C o /C s increases while the value of the specific energy intensity Е o /Е s decreases. It was found that such a change in the characteristics of the self-oscillatory grinding is predetermined by an increase in the dynamic effect of grinding load on the crushed material due to the influence of a separate factor.…”

“…However, the significant variability in the self-oscillatory behavior in the rotating chamber, depending on the complex multi-factional poly grain load structure, significantly complicates the establishment of rational conditions for the effective implementation of such a milling process. This structure is quantitatively characterized by both the degree of filling the chamber with grinding bodies κ br [4] and the degree of filling the gaps between these bodies with particles of the crushed material κ mbgr [5].…”

Establishing the Rotation Speed Variation Range Limits for Auto-Excitation of Self-Oscillating Grinding in a Tumbling Mill

“…The applied value of the pulsating behavior of the intra-chamber feeding lies in the use of an innovative self-oscillating grinding process in a tumbling mill [3]. The energy efficiency of such a process increases with a decrease in the degree of filling the chamber [4] and the content of the crushed material in the feeding [5].…”