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

Yuriy Naumenko,Kateryna Deineka

doi:10.15587/1729-4061.2020.209050

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 bodies 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

Highlights

Tumbling mills continue to be the main equipment for multi-ton fine grinding of various materials in many industries
The study objective is to establish the influence of the content of crushed material in the chamber fill on cha racteristics of the dynamic action of pulsation filling and parameters of conventional and self-oscillatory grinding processes in a tumbling mill
Experimental dependences of numerical values of maximum dilatancy, relative amplitude of self-oscillations, share of the active part of the fill and the degree of dynamic activation characterize the influence of the content of crushed material on dynamic action of the grinding bodies

Summary

Introduction

Tumbling mills continue to be the main equipment for multi-ton fine grinding of various materials in many industries. The application of the self-oscillatory grinding process is a new technological line to a significant increase in the relatively low energy efficiency of such mills. The auto-excitation of self-oscillations makes it possible to set in motion and activate the passive part of the intra-mill fill and significantly increase the intensity of interaction between grinding bodies and the crushed material. The problem of forecasting the influence of the content of the crushed material in the intra-chamber fill on dynamic action of grinding bodies and technological and energy efficiency of the self-oscillatory process of grinding in a tumbling mill seems to be quite relevant

Literature review and problem statement

The aim and objectives of the study

Findings

Conclusions