Grinding cylpebs are slightly tapered cylindrical grinding media with a ratio
of length to diameter of unity. The manufactures have made conflicting claims
regarding the milling performance of Cylpebs in comparison with balls. One major
point of interest is which one grinds finer at the same operating conditions.
The difficulty in comparison is due to the shape difference. The two grinding
media have different surface area, bulk density and contact mechanisms in
grinding action.
Comparative tests were conducted using the two types of grinding media in a
laboratory Bond ball mill at various conditions of equality such as media mass,
size distribution, surface area and input specific energy. The laboratory
results indicate that at the same specific energy input level the Cylpebs
produce a product with slightly less oversize due to their greater surface area,
but essentially the same sizing at the fine end as that produced with the balls.
The reason may be that the advantage of greater surface area is balanced by the
line contact and area contact grinding actions with the Cylpebs.
A new ball mill scale-up procedure [Man, Y.T., 2001. Model-based procedure
for scale-up of wet, overflow ball mills, Part I: outline of the methodology.
Minerals Engineering 14 (10), 1237–1246] was employed to predict grinding
performance of an industrial mill from the laboratory test results. The
predicted full scale operation was compared with the plant survey data. Some
problems in the original scale-up procedures were identified. The scale-up
procedure was therefore modified to allow the predicted ball mill performance to
match the observed one. The calibrated scale-up procedure was used to predict
the Cylpebs performance in the full scale industrial mill using the laboratory
tests results.
