A method to predict shape and trajectory of charge in industrial mills

Moghaddam, M. M., Mohsen, Yahyaei and Banisi, S. (2012). A method to predict shape and trajectory of charge in industrial mills. In: Pradip (Conference President), XXVI International Mineral Processing Congress - IMPC 2012: Conference Proceedings. XXVI International Mineral Processing Congress - IMPC 2012, New Delhi, India, (3189-3203). 24-28 September 2012.

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Name Description MIMEType Size Downloads
Author Moghaddam, M. M.
Mohsen, Yahyaei
Banisi, S.
Total Author Count Override 3
Title of paper A method to predict shape and trajectory of charge in industrial mills
Conference name XXVI International Mineral Processing Congress - IMPC 2012
Conference location New Delhi, India
Conference dates 24-28 September 2012
Proceedings title XXVI International Mineral Processing Congress - IMPC 2012: Conference Proceedings
Place of Publication New Delhi, India
Publisher Technowrites
Publication Year 2012
Sub-type Fully published paper
ISBN 8190171437
Editor Pradip (Conference President)
Start page 3189
End page 3203
Total pages 15
Collection year 2013
Language eng
Formatted Abstract/Summary
Charge motion is of prtme importance in the efficiency of comminution in tumbling mills. Since direct
observation of charge shape and its motion in industrial mill are not possible, a combination of
analytical and physical studies was used to determine charge trajectory. Software packages, which
predict charge motion such as the GMT (Grinding Media Trajectory) only consider the outermost layer
of charge (single ball) and ignore the interactions of grinding elements. In this research, the measured
charge trajectory in a 1m-diameter mill with the transparent end, called model mill, was compared with
that of the GMT. Four types of polyurethane rings were accurately machined to scale down the liners
arrangements at two industrial mills. To explore various charge shapes and trajectories, the model mill
was operated at 55, 70 and 85% of critical speed for five levels of mill filling (10, 15, 20, 25 and 30%
by volume). The angular displacement of the toe, toe departure, shoulder and charge impact point
were determined from the photographs taken from the model mill. New relationships to predict charge
shape and charge impact points were introduced to modify the GMT results. The relationships were
validated by the model mill using the new liner of the Sarcheshmeh copper complex SAG mill. The
relative error of prediction was found to be 1.1 %. The results indicated that when the lifter face angle
increased from 7 to 30°, the distance between the charge impact point and the toe decreased from 52
to 31° for 25% filling. This meant increasing the probability of charge impacting the toe not the liner
which favoured more efficient comminution practice. After converting AG mills to SAG mills on account
of liner profile change, 31% increase in throughput (from 419 to 548 tlh) in addition to 4% decrease in
the product size (from 516 to 496 µm) were realized which was a significant contribution in the plant
performance improvement.
Keyword SAG mill
Charge motion
Charge shoulder
Q-Index Code E1
Q-Index Status Confirmed Code
Institutional Status UQ

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Created: Mon, 08 Oct 2012, 13:15:50 EST by Karen Holtham on behalf of Julius Kruttschnitt Mineral Research Centre