Revealing the effect of decreased energy intensity of grinding in a tumbling mill during self-excitation of auto-oscillations of the intrachamber fill

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Оцінено вплив величини ступеня заповнення камери завантаженням на ефективність автоколивного процесу подрібнення в барабанному млині. За допомогою наближеного аналітико-експериментального методу встановлено динамічний ефект підвищення автоколивної ударної дії молольного завантаження на подрібнюваний матеріал порівняно із традиційним усталеним режимом руху. Виявлено суттєве зростання середніх сум вертикальних складових автоколивних ударних імпульсів та середніх сум потужностей таких складових зі зменшенням заповнення камери. Прояв ефекту зумовлено збільшенням розмаху автоколивань при зменшенні заповнення. Виявлено зростання максимальних значень імпульсів приблизно у 2,4 рази при ступені заповнення κ = 0,45, у 3,1 рази при κ = 0,35 та у 5,8 рази при κ = 0,25. Встановлено зростання максимальних значень потужностей імпульсів у 5,7 рази при κ = 0,45, у 9,6 рази при κ = 0,35 та у 45,5 рази при κ = 0,25. Експериментально встановлено технологічний ефект суттєвого спадання питомої енергоємності та зростання продуктивності інноваційного автоколивного процесу подрібнення, порівняно із характеристиками традиційного усталеного процесу, зі зменшенням заповнення камери. Було розглянуто процес помелу цементного клінкера при повному заповненні частинками подрібнюваного матеріалу проміжків між кульовими молольними тілами із відносним розміром 0,026. Встановлено, що під час самозбудження автоколивань енергоємність подрібнення спадає, а продуктивність зростає. Виявлено зниження відносної питомої енергоємності на 27 % при κ = 0,45, на 42 % при κ = 0,35 та на 55 % при κ = 0,25. Встановлено підвищення відносної продуктивності на 7 % при κ = 0,45, на 30 % при κ = 0,35 та на 46 % при κ = 0,25. Встановлені в роботі ефекти дозволяють прогнозувати раціональні параметри автоколивного процесу подрібнення в барабанному млині при варіації ступеня заповнення камери Ключові слова: барабанний млин, ступінь заповнення камери, автоколивання завантаження, питома енергоємність подрібнення

“…The creeping layer and the restricted fall zone partially (Fig. 5, [9]) or completely ( Fig. 6) transform into this zone.…”

Section: The Procedures Of Studying the Effect Of Degree Of Chamber Fimentioning

confidence: 99%

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Section: The Procedures Of Studying the Effect Of Degree Of Chamber Fimentioning

confidence: 99%

Section: The Procedures Of Studying the Effect Of Degree Of Chamber Fimentioning

confidence: 99%

Section: The Procedures Of Studying the Effect Of Degree Of Chamber Fimentioning

confidence: 99%

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Establishing the effect of a decrease in power intensity of self-oscillating grinding in a tumbling mill with a reduction in an intrachamber fill

Deineka

Naumenko

2019

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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

Deineka

Naumenko

2020

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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

Deineka¹,

Naumenko²

2021

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The effect of a simultaneous change in the degree of filling a chamber with load κbr and in the content of the crushed material κmbgr on the efficiency of the self-oscillatory grinding process has been estimated. Using a method of numerical modeling based on the results of experimental visualization of the flow has helped establish an emergent dynamic effect of the sharp increase in the self-oscillatory action of two-faction loading at a joint reduction in κbr and κmbgr. A significant decrease in the passive quasi-solid loading motion zone has been detected, as well as an increase in the active pulsation zone and a growth of dilatancy. The manifestation of the effect is enhanced by the simultaneous interaction of increasing the scope of self-oscillations and weakening the coherent properties of particles in a loose large fraction under the influence of the particles of fine fraction. A significant decrease in the values of the inertial loading parameters has been established: maximum dilatancy υmax, the relative scale of self-oscillations ψRυ, the maximum share of the active part of κfammax, and the generalized complex degree of dynamic activation Ka. A 2.65-time growth of υmax was detected, ψRυ increased by 5 times, κfammax ‒ by 4.36 times, Ka ‒ by 18.4 times, at a joint decrease in κbr from 0.45 to 0.25, in κmbgr ‒ from 1 to 0. The synergistic technological effect of a sharp decrease in the specific energy intensity Еo/Еs has been established, as well as an increase in the relative performance Co/Cs in the self-oscillatory grinding, due to a significant increase in the dynamic action of loading, which is exacerbated by the joint interaction of reduced κbr and κmbgr. The process of the self-oscillatory grinding of cement clinker has been investigated. A 62 % reduction in Еo/Еs and a 125 % increase in Co/Cs were detected at a joint decrease in κbr from 0.45 to 0.25, in κmbgr ‒ from 1 to 0.125. The established effects make it possible to substantiate the parameters for the energy-efficient self-oscillatory process of grinding in tumbling mills with a conventional structure