A specific energy-based size reduction model for a batch grinding
ball mill has been developed and implemented in the SDK version
of JKSimMet. Distinguished from the prior-art population
balance models, this specific energy-based model calculates the
particle breakage index, t10, based on the size-specific energy,
and then calculates the product size distribution by using the
t10–tn relationships and the mass-size balance approach. The
model includes an ore-specific and size-dependent breakage function,
with its parameters being independently measured by using a
fine particle breakage characteriser, the JKFBC. This has effectively
overcome the limitation of using a default breakage appearance
function in the JKMRC perfect mixing ball mill model.
Batch grinding data using a Bond ball mill were collected to test
the upgraded size reduction model. The model fits the batch grinding
data well. The calibrated model from one ore sample was used
to predict the breakage results for another ore with the measured
ore characteristic parameters. The same approach was applied to
the JKSimMet ball mill model. Comparison of the predictions by
the two models shows better results from the upgraded model.
Work is underway to incorporate classification mechanism in
the size reduction model for applications in continuous ball mill
operation.