Effects of grinding media shapes on ball mill performance
Student number : 0318567G School of Chemical and Metallurgical Engineering Faculty of Engineering === Comminution is an important process in mineral processing, power plants, cement production and pharmaceutical industries. It is costly and an inefficient process in terms of energy requirements...
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ndltd-netd.ac.za-oai-union.ndltd.org-wits-oai-wiredspace.wits.ac.za-10539-15062019-05-11T03:40:47Z Effects of grinding media shapes on ball mill performance Lameck, Niyoshaka Nistlaba Stanley grinding comminution power load behaviour grinding media breakage kinetics Student number : 0318567G School of Chemical and Metallurgical Engineering Faculty of Engineering Comminution is an important process in mineral processing, power plants, cement production and pharmaceutical industries. It is costly and an inefficient process in terms of energy requirements and steel consumption related to grinding media and liners. Spherical grinding media are predominantly used in final stages of ore grinding. The spherical balls change shape through breakage and wear. Though this is universal in milling, its contribution and effect on milling kinetics, load behaviour and mill power is not fully established. One area that is usually ignored is the relationship between media shape and mill power. The objective of this dissertation was to investigate how media shape affects grinding. Ball size distribution inside an industrial mill was analysed in terms of shapes and sizes. Load behaviour, mill power and breakage as affected by media shapes were studied in a pilot laboratory mill. An inductive proximity probe, light emitting diode, phototransistor and video photographs were used to determine the load orientation in terms of toe and shoulder positions. A load beam was used to measure the torque exerted by the charge. The variation in load orientation and mill power with speed among different media shapes was observed. Higher shoulder positions were noted with cylpebs than with worn and spherical balls. The power increased to a maximum with increasing mill speed for all media shapes reaching its peak at different mill speeds for the three shapes studied. Variations of breakage rates with media shapes were found; higher breakage rates were noted with spherical media but the differences narrows with decreasing feed size and increasing material fractional filling U. Considering that worn balls in an industrial mill charge constitute about 15 to 40 percent and that the highest difference in breakage rate observed being nine percent for purely one shape charge; it is very doubtful whether it is worthwhile in attempting to develop techniques for removing worn balls from the mill. 2006-10-31T06:53:13Z 2006-10-31T06:53:13Z 2006-10-31T06:53:13Z Thesis http://hdl.handle.net/10539/1506 en 1073957 bytes application/pdf application/pdf |
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grinding comminution power load behaviour grinding media breakage kinetics |
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grinding comminution power load behaviour grinding media breakage kinetics Lameck, Niyoshaka Nistlaba Stanley Effects of grinding media shapes on ball mill performance |
description |
Student number : 0318567G
School of Chemical and Metallurgical Engineering
Faculty of Engineering === Comminution is an important process in mineral processing, power plants, cement
production and pharmaceutical industries. It is costly and an inefficient process in
terms of energy requirements and steel consumption related to grinding media and
liners.
Spherical grinding media are predominantly used in final stages of ore grinding. The
spherical balls change shape through breakage and wear. Though this is universal in
milling, its contribution and effect on milling kinetics, load behaviour and mill power
is not fully established. One area that is usually ignored is the relationship between
media shape and mill power.
The objective of this dissertation was to investigate how media shape affects
grinding. Ball size distribution inside an industrial mill was analysed in terms of
shapes and sizes. Load behaviour, mill power and breakage as affected by media
shapes were studied in a pilot laboratory mill. An inductive proximity probe, light
emitting diode, phototransistor and video photographs were used to determine the
load orientation in terms of toe and shoulder positions. A load beam was used to
measure the torque exerted by the charge.
The variation in load orientation and mill power with speed among different media
shapes was observed. Higher shoulder positions were noted with cylpebs than with
worn and spherical balls. The power increased to a maximum with increasing mill
speed for all media shapes reaching its peak at different mill speeds for the three
shapes studied.
Variations of breakage rates with media shapes were found; higher breakage rates
were noted with spherical media but the differences narrows with decreasing feed size
and increasing material fractional filling U. Considering that worn balls in an industrial mill charge constitute about 15 to 40
percent and that the highest difference in breakage rate observed being nine percent
for purely one shape charge; it is very doubtful whether it is worthwhile in attempting
to develop techniques for removing worn balls from the mill. |
author |
Lameck, Niyoshaka Nistlaba Stanley |
author_facet |
Lameck, Niyoshaka Nistlaba Stanley |
author_sort |
Lameck, Niyoshaka Nistlaba Stanley |
title |
Effects of grinding media shapes on ball mill performance |
title_short |
Effects of grinding media shapes on ball mill performance |
title_full |
Effects of grinding media shapes on ball mill performance |
title_fullStr |
Effects of grinding media shapes on ball mill performance |
title_full_unstemmed |
Effects of grinding media shapes on ball mill performance |
title_sort |
effects of grinding media shapes on ball mill performance |
publishDate |
2006 |
url |
http://hdl.handle.net/10539/1506 |
work_keys_str_mv |
AT lameckniyoshakanistlabastanley effectsofgrindingmediashapesonballmillperformance |
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