1. The study uses discrete element modeling (DEM) to simulate particle movement in two types of impact crushers: a vertical shaft impact crusher and a horizontal shaft hammer mill. 2. DEM simulations calculate velocity, energy distribution, and product size distribution, which agree reasonably well with experimental data from the crushers. 3. DEM provides insights into how particle size, feed position, and crusher operating conditions affect kinetic energy, strain energy, and breakage behavior inside the crushers.

1. Applying discrete element modelling to vertical
and horizontal shaft impact crushers
N. Djordjevic, F.N. Shi *, R.D. Morrison
Julius Kruttschnitt Mineral Research Centre, The University of Queensland, Isles Road, Indooroopilly, Brisbane 4068, Australia
Received 25 June 2003; received in revised form 17 August 2003
Abstract
The PFC3D (particle flow code) that models the movement and interaction of particles by the DEM techniques was employed to
simulate the particle movement and to calculate the velocity and energy distribution of collision in two types of impact crusher: the
Canica vertical shaft crusher and the BJD horizontal shaft swing hammer mill. The distribution of collision energies was then
converted into a product size distribution for a particular ore type using JKMRC impact breakage test data. Experimental data of
the Canica VSI crusher treating quarry and the BJD hammer mill treating coal were used to verify the DEM simulation results.
Upon the DEM procedures being validated, a detailed simulation study was conducted to investigate the effects of the machine
design and operational conditions on velocity and energy distributions of collision inside the milling chamber and on the particle
breakage behaviour.
Ó 2003 Elsevier Ltd. All rights reserved.
Keywords: Crushing; Comminution; Modelling; Simulation
1. Introduction
Impact-induced rock fragmentation is relevant for
many fields of science and technology. The length scale
involved in this process span from domain of astro-
physics to domain of geophysics and finally to the scale
of fragments and agglomerates in the chemical and
pharmaceutical industries. Impact crushers have been
applied in mineral, food, coal and cement industries for
a long time. The literature shows that substantial effort
has been expended in understanding the impact crusher
performance in relation to machine configuration and
operational conditions through experimental work and
mathematical modelling (Callcott, 1960; Austin et al.,
1979; Gotsis et al., 1985; Shi, 2002; Shi et al., 2003).
However, due to lack of detailed knowledge on velocity
and energy distributions of collision inside a milling
chamber, the mechanisms are still not clear.
The discrete element method (DEM) was employed in
the present work to study the kinematics of the particle
motion within the impact crushers. The DEM was first
proposed by Cundall and Strack (1979) to model the
behavior of soil particles subject to dynamic loading
conditions. Since its inception this technique has been
adapted to model a variety of physical systems. Mishra
(1991) and Mishra and Rajamani (1992, 1994) pioneered
the application of DEM to grinding mills and demon-
strated that despite the DEM simulations were two-
dimensional (2D), the technique was able to predict the
power draw of mills with reasonable accuracy over a
wide range of mill diameters. Over 10 years since then,
the DEM technique has been widely applied to ball mills
(e.g. Cleary, 1998, 2001; van Nierop et al., 2001), SAG
mills (e.g. Rajamani et al., 2000; Morrison et al., 2001),
centrifugal mill (Inoue and Okaya, 1996; Cleary and
Hoyer, 2000). Meanwhile the DEM code has been ex-
tended from 2D to 3D, and the contact parameters in-
volvedintheDEMmodelhavebeenstudiedandcorrected
to improve the simulation accuracy (e.g. Zhang and
Whiten, 1996, 1998; Mishra and Murty, 2001).
The DEM has also been applied to studies of impact-
induced particle breakage. Potapov and Campbell
(1994) found that ratio of the impact velocity to prop-
agation velocity of the longitudinal (sound) waves in the
material (Vo=C) was a useful parameter that described
the rate at which the kinetic energy of the collision was
transferred to the strain energy of the particle. When the
value of Vo=C was high, the produced fragments tended
*
Corresponding author. Tel.: +61-7-3365-5888; fax: +61-7-3365-
5999.
E-mail address: f.shi@uq.edu.au (F.N. Shi).
0892-6875/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.mineng.2003.08.007
Minerals Engineering 16 (2003) 983–991
This article is also available online at:
www.elsevier.com/locate/mineng

2. to have an elongated shape. This was in agreement with
experimental results. Thornton et al. (1996) reported
about 2D DEM of agglomerates impacting the rigid
walls. Depending on the impact velocity and adhesive
strength between particles, three regimes were observed:
shattering, semi-brittle fracture and elastic rebound.
Mishra and Thornton (2001) have studied the impact
breakage of particle agglomerates. They found a dis-
tinct fracture pattern for dense agglomerates above
a threshold impact velocity. The produced fragment
size distributions showed a clear bi-modal distribu-
tion. However, application of the DEM to the impact
crushers was rare in the literature.
Over years the Julius Kruttschnitt Mineral Research
Centre (JKMRC) has successfully modelled two types of
impact crushers: the vertical shaft impact crusher (Na-
pier-Munn et al., 1996) and the horizontal shaft swing
hammer mill (Shi, 2002; Shi et al., 2003). In the present
work the PFC3D (particle flow code) that models the
movement and interaction of particles by DEM tech-
niques was employed to model the two types of impact
crusher. Modelling of fragmentation has also been at-
tempted using a strain rate concept. The data collected
from a Canica crusher treating quartzite and a BJD
swing hammer mill treating coal were used to verify the
DEM simulation results of specific energy and fragment
size distribution.
Upon the DEM procedures being validated, a detailed
simulation study was conducted to investigate the effects
of the machine design and operational conditions on
velocity and energy distributions of collision inside the
milling chamber and on the particle breakage behaviour.
2. The PFC3D models of impact crushers
Impact crusher modelling has been performed using
the PFC3D discrete element code. This code models the
behaviour of particles, which may be enclosed within a
finite volume by the non-deformable walls. The code
keeps a record of individual particles and updates any
contact with other particles or walls. Each calculation
step includes application of the law of motion to a
particle, a force–displacement law to each contact and
constant updating of the wall position (Cundall and
Strack, 1979). Details of the DEM calculation of contact
force, shear stiffness and slip model are referred to other
publication (Djordjevic, 2003).
Two types of impact crushers were modelled using
the PFC3D code. The Canica Model 90 is an industrial-
scale vertical shaft impact crusher with 5 impellers of
0.48 m in their tip rotating radius. The crusher is fed by
a belt feeder. Rocks drop into the centre of the rotor,
and are hit or accelerated by the impellers to impact on
the surrounding anvils. The distance from the rotor
centre to the surface of the anvil is 0.65 m. The Canica
crusher was employed to treat quartzite. The rotational
speeds of the crusher varied from 650 to 950 rpm in the
experiment at an average throughput of 102 tph.
The BJD swing hammer mill is a pilot-scale hori-
zontal shaft impact crusher. The hammer tip diameter is
0.38 m, mill width 0.20 m, with a nominal capacity of 3
tph when driven by a 5.6 kW motor. The rotor, rotating
at a fixed speed of 3000 rpm, carries four rows of rect-
angular hammers with a width 0.03 m, two rows of three
hammers and two rows of two hammers. The BJD
hammer mill was employed to treat coal.
The Canica vertical shaft impact crusher is repre-
sented by a cylindrical chamber and five rotating im-
pellers in the DEM simulations (Fig. 1). Feed comes
from 1 m above in the form of free falling particles. The
code is designed to perform modelling in 3D. Similarly,
the model for the BJD horizontal shaft hammer mill is
given in Fig. 2. For simplicity in the DEM calculation
code, the double-shaft swing hammers were simplified as
single-shaft rigid hammers.
For the Canica vertical impact crusher, test data at
950 rpm was used. The feed ()75 mm +2.36 mm) was
converted to the distribution of number of particles in
each size fraction. A total of 341 particles were simu-
lated. The fine end of the feed ()2.36 mm) was truncated
as there were more than 8000 particles in this size frac-
tion, which takes a very long computing time. The
truncated )2.36 mm material (4% by weight of the total
feed) was added into the DEM simulation product for
comparison with the measured data. For the BJD hori-
zontal shaft crusher, on the other hand, the data from the
test of single lithotype coal (the dull coal) of narrowly
Fig. 1. PFC3D model of vertical shaft Canica crusher (view from
below).
984 N. Djordjevic et al. / Minerals Engineering 16 (2003) 983–991

3. sized feed (8–16 mm) was used. 340 particles of same size
(11.3 mm) were simulated using the PFC3D code.
The DEM modelling calculates the total cumulative
energy applied to each particle, including various forms
of energy due to collisions between impellers and par-
ticles, particles and anvils, and particles to particles. The
total specific energy for the Canica test at 950 rpm, de-
termined through PFC3D modelling, is 0.43 kW h/t,
compared with 0.32 kW h/t kinetic energy determined
from the impeller tip velocity. For the BJD horizontal
hammer mill, the total specific energy determined by
DEM is 0.23 kW h/t. This is very close to the model
parameter Ecs ¼ 0:21 kW h/t fitted to the BJD hammer
mill experimental data (Shi et al., 2003).
The fragmented product size distributions were then
determined from the specific energy using a relationship
established from the single particle impact breakage test
(Napier-Munn et al., 1996). A crusher model imple-
mented in the JKSimMet software was employed to es-
timate the product size distribution from the total energy
determined by the DEM. The crusher K-parameters
were kept constant as determined from the previous
model fitting. The predicted size distributions were
compared with the experimental data, given in Fig. 3.
For the Canica vertical shaft impact crusher, the
DEM prediction of product size is in good agreement
with the experimental data at a size range coarser than
10 mm, but over-predicts for fine product. This may be
due to the fact that more than 8000 particles smaller
than 2.36 mm were removed from the DEM simulation.
Although this fraction of materials only account for 4%
by weight in the feed, the cushion effect of these particles
on the collision energy may be significant. Thus the total
cumulative specific energy should be smaller than the
one presented in this work. Similarly, the DEM pre-
diction for the BJD horizontal shaft crusher is good at
coarser size fractions (>2 mm), but over-predicts fines.
This may be attributed to the over-simplified one-shaft
configuration of hammers used in the DEM, while the
BJD mill operates with double-shaft swing hammers.
Nevertheless, the DEM predictions seem to follow
the general trends of the experimental data very well.
This verifies that the DEM simulations can provide
reasonable insight of the impact crusher performance. A
number of simulations regarding the effects of machine
design and operational conditions on the impact crusher
were then conducted.
3. Descriptions of particle kinematics by DEM simula-
tions
The impact crushers usually operate at very high ro-
tational speed (1000 rpm for the vertical shaft crusher
and 3000 rpm for the horizontal shaft hammer mill in
this study). Dynamic motion of particles inside the
crushing chamber and the interaction between the
crushing element and the particles exerts a dominant
influence on product size distribution. However, such
knowledge is rare in the literature. Although high-speed
cine camera study on the motion of coal particles inside
the BJD hammer mill was attempted by researchers (e.g.
Callcott, 1960), it was difficult to determine the impact
energy quantitatively. DEM simulations provide a
suitable tool to establish the particle kinematics and the
energy distribution patterns.
3.1. Specific energy in relation to particle size
Investigation was conducted of the effect of particle
size on the intensity of the introduced energy and the
nature of the energy split for various rotational speeds
Fig. 2. PFC3D model of horizontal shaft BJD hammer mill.
0.0
20.0
40.0
60.0
80.0
100.0
0.1 1 10 100
Size (mm)
Cum.%passing
BJD product BJD feed
Canica product
Canica feed
Fig. 3. Comparison of size distributions simulated by DEM (in lines)
with measured (in symbols) for the Canica vertical shaft impact
crusher and the BJD horizontal shaft hammer mill.
N. Djordjevic et al. / Minerals Engineering 16 (2003) 983–991 985

4. of the impellers in the vertical shaft crusher. The particle
size studied was in the range of 10–70 mm. Single
spherical particles were dropped from a height of 1 m, at
a position that corresponds to half of the impeller
length. The results show that kinetic energy is a domi-
nant form of energy and the amount of specific kinetic
energy (kW h/t) is a function of the particle size and the
rotational speed of impellers (Fig. 4a and b).
When the impact crusher operates at a low rotational
speed (650 rpm), the specific kinetic and strain energy
are almost independent of the particle size. The ratio of
strain (deformation) energy to kinetic energy is practi-
cally constant (approximately 0.45). However, as the
rotational speed increases, both specific kinetic energy
and specific strain energy increase significantly below
certain particle sizes, but decrease for larger particle
sizes. The ratio of strain energy to kinetic energy is
basically constant for small particles, but it increases for
large particles as the impeller speed increases.
3.2. Specific energy in relation to feed position
The effect of particles feeding position to the vertical
shaft impact crusher was investigated numerically for
the case of 40 mm-diameter particles in the crusher with
impellers rotating at a speed of 650 rpm. The energy
introduced to the particles is a function of the position
along the impeller where contact with the particle oc-
curs. Radial velocity of the specific point along the im-
peller is determined by the angular velocity of the
impeller and the distance from the rotation centre. In
order to minimise the rolling effect of the particles, the
friction coefficient between particles and crusher sur-
faces were increased to a high value. This may be re-
flected to the effect of irregular particle shape of natural
rock material, which often has a relatively high effective
coefficient of friction. Results show that both specific
kinetic and strain energy increase as the impact point
becomes closer to the tip of the impeller (Fig. 5).
3.3. Particle kinematics
DEM is a suitable tool for investigation of the par-
ticle motion after initial impact, particularly in gaining
insight into the particle motion when interception of the
particle by the impeller occurs away from the impeller
tip. Simulations were performed in the vertical shaft
impact crusher using a cube composed from a number
of rigid balls bonded together to represent a rock sam-
ple. The strength of the sample was kept constant, while
the impeller varied.
Fig. 6 shows that at low rotational speeds the rock
just bounces on the surface of the impeller, while at
higher speeds some breakage occurs due to the initial
impact.
Fig. 7 shows the breakage process for the samples
built from 5 and 2.5 mm-radius balls respectively. As-
suming that bond strength between individual balls re-
mains the same, a decrease in the ball size (grain size in
real life) would produce a particle of higher strength.
Fig. 7 demonstrates that the initial impact results in
0
0.1
0.2
0.3
0.4
0.5
0 20 40 60 80
Particle diameter (mm)
Specifickineticenergy(kWh/t)
650 rpm 850 rpm 950 rpm
0
0.1
0.2
0.3
0.4
0.5
0 20 40 60 80
Particle diameter (mm)
Specificstrainenergy(kWh/t)
650 rpm 850 rpm 950 rpm
(a) (b)
Fig. 4. Specific energy as a function of particle size and speed of the crusher. (a) kinetic energy, (b) strain energy.
0
0.02
0.04
0.06
0.08
0.1
0.12
0 100 200 300 400 500
Distance from the centre of the crusher (mm)
Specificenergy(kWh/t)
Kinetic
Strain
Fig. 5. Specific strain and kinetic energy introduced as a function of
distance of the impact point from the centre of the impeller.
986 N. Djordjevic et al. / Minerals Engineering 16 (2003) 983–991

5. breakage of particles close to the surface of the impeller.
The tensile strain causes the sample to split. The heavily
damaged sample slides along the surface of the impeller
towards its tip. Comparing Fig. 7a with b, the particle
with smaller grain size appear to be less damaged after
colliding with the impeller. This supports the assump-
tion that particles with smaller grain size have a higher
strength.
It is interesting to observe that both large and small
fragments tend to migrate along the surface of the
Fig. 6. Collision of particles with impeller at various rotational speeds. (a) Sample remains intact after collision with impeller rotating at 100 rpm, (b)
sample remains intact after collision with impeller rotating at 500 rpm, (c) breakage occurs after collision with impeller rotating at 700 rpm.
Fig. 7. Breakage process of particles built from different grains at an impeller speed of 900 rpm. (a) Sample immediately after impeller impact (grain
radius ¼ 5 mm); (b) sample immediately after impeller impact (grain radius ¼ 2.5 mm); (c) sample immediately after impact to anvil (grain radius ¼ 5
mm); (d) sample immediately after impact to anvil (grain radius ¼ 2.5 mm).
N. Djordjevic et al. / Minerals Engineering 16 (2003) 983–991 987

6. impeller towards its tip. When they reach the tip, the
fragments take-off with a maximum possible velocity
towards the surrounding anvils of the crusher. The
dominant phase of fragmentation occurs when the par-
ticles hit the anvils.
3.4. Energy distribution
In order to further investigate the effect of the inter-
cept position on the energy introduced into particles, a
25 mm cube made from 125 balls was placed in the
vertical shaft impact crusher at a distance of 5 and 45 cm
from the centre of the crusher respectively. Rotational
rate of the impeller was kept constant (1000 rpm). Re-
sultant (vector sum) velocity and total accumulative
specific energy of the cube are given in Figs. 8 and 9.
When particles are dropped close to the centre, the
impact velocity is not sufficient to cause fragmentation.
Particles are then translated and bounced along the
length of the impeller until they reach its tip. They are
accelerated at the tip speed towards the crusher anvils.
In such cases the initial fragmentation due to impact is
missed, but the secondary fragmentation due to impact
on the surrounding anvils remains.
Fig. 8. Resultant velocities for the samples intercepted by the impeller at different positions. (a) Close to the centre of the crusher (5 cm away from
the centre), (b) close to the tip of the impeller (45 cm away from the centre).
Fig. 9. Accumulated specific energy for the samples intercepted by the impeller at different positions. (a) Close to the centre of the crusher (5 cm away
from the centre), (b) close to the tip of the impeller (45 cm away from the centre).
988 N. Djordjevic et al. / Minerals Engineering 16 (2003) 983–991

7. On the other hand, where the particle is intercepted
near the tip of impeller, the initial impact is sufficient
to fragment the sample. After the impact, the individ-
ual grains are directed towards the crusher anvils
where further fragmentation occurs. However, the ini-
tial fragmentation due to the impact of impeller is
dominant. Although the peak resultant velocity of the
ball intercepted near the impeller tip is slightly smaller
than that intercepted near the impeller centre (87.4 vs.
89.8 m/s), the total accumulative specific energy intro-
duced into the sample is about 23% higher (0.87 vs. 0.71
kW h/t).
Fig. 9 also shows that the amount of energy intro-
duced into the particles rapidly increases when the
sample hits the crusher anvils and becomes heavily
fragmented. Particularly there is a large increase in shear
energy. This occurs due to the large increase in the
surface area of fragments that are sliding in contact with
the crusher anvils. The shear forces are a significant
factor in producing fines.
4. Analytical modelling of rock fragmentation in impact
crushers
An impact crusher fragments the rock by the dynamic
strain energy introduced into the feed by the impactor.
The process of dynamic fragmentation, by its nature,
exploits the existence of flaws and micro-discontinuities.
Hence, product fragments tend to be of good quality
and shape. Specific fragmentation energy introduced
into the rock is a function of the impacting velocity. The
initial impact velocity is a function of the rotational
velocity of the crusher as well as the position along the
impeller, where falling feed becomes intercepted by the
rotating impellers.
For high velocity crushers, the initial collision is fre-
quently a significant cause of fragmentation. Any sub-
sequent crushing only complements the crushing action
of the impeller. The intensity of dynamic stress induced
by the impeller and by impact into the fixed surface can
be calculated using a simple equation:
S ¼ qVpVpp ð1Þ
where S is the dynamic stress (Pa), q is the rock density
(kg/m3
), Vp is the propagation velocity of the longitu-
dinal stress wave in the material (m/s), Vpp is the peak
particle velocity (m/s).
The peak particle velocity at the contact point of the
rock and impeller, for the simplest case, is equal:
Vpp ¼ Vi ð2Þ
where Vi is impact velocity (m/s).
Impact velocity of the impeller is determined by the
angular (rotational) velocity of the impeller as well as
the distance from the centre of rotation where impact
occurs, described by the formula:
Vi ¼ Xd ð3Þ
where X is the angular velocity of the impeller (rad/s), d
is the distance from the centre along the impeller where
collision occurs (m).
Using this simple model, it can be shown that inten-
sity of initial impact stress is determined by the rota-
tional speed and distance from the centre of rotation
where collision occurs (Fig. 10).
Effect of the initial impact can be calculated based on
the theory of dynamic fragmentation developed by
Grady (1985). Based on energy considerations at high
strain rates, Grady developed a relationship for the
mean fragment size based on the induced strain rate and
rock properties such as fracture toughness, density and
the propagation velocity of elastic waves, using the
equation:
D ¼
4:472 Â Klc
q  Vp  Sr
2=3
ð4Þ
where D is mean fragment size produced by the impact
(m), Klc is fracture toughness (mode 1) of the rock
(Pa m0:5
), q is rock density (kg/m3
), Vp is propagation
velocity of the longitudinal elastic waves in the rock (m/
s), Sr is the induced strain rate (1/s).
Grady’s model has been successfully applied in the
modelling of rock fragmentation induced by explosives.
The strain rate in the sample is defined as the difference
in rock particle velocity at the point of impact and at the
opposite, free end of the rock sample. The strain rate
can be calculated from the rotational velocity of the
impeller and the radial distance between the centre of
rotation and impact point:
0
200
400
600
800
1000
1200
1400
1600
1800
0 500 1000 1500 2000 2500 3000 3500
Rotational velocity (rpm)
Inducedstress(MPa)
d = 0.5 m
d = 0.1 m
Fig. 10. Effect of the rotational speed and distance of the impact point
from the centre of rotation on the intensity of induced stress in the
rock.
N. Djordjevic et al. / Minerals Engineering 16 (2003) 983–991 989

8. Sr ¼
Vpp1 À Vpp2
L
ð5Þ
where Vpp1 and Vpp2 are particle peak velocities at the
impact point and at the free end of the particle respec-
tively, and L is linear dimension of the rock sample (m).
Considering that particle peak velocity Vpp1 at the
interface of the impeller and rock is equal to the impeller
impact velocity Vi, and that Vpp2 at the free end of the
rock sample is of opposite sign of Vpp1 (due to reflection
from the free surface), and ignoring strain attenuation in
the rock sample and the effect of transit time, the strain
rate can be represented as
Sr ¼
2 Â Vi
L
ð6Þ
Combining Eqs. (3), (4) and (6) gives the mean product
size due to impact:
D ¼
4:472  Klc  L
0:133  q  Vp  pWd
2=3
ð7Þ
where W is rotational speed in rpm.
Application of this equation for the case of a rock
with density q ¼ 2650 kg/m3
, Vp ¼ 4000 m/s, fracture
toughness Klc ¼ 1 MPa m0:5
, size L ¼ 0:1 m and radial
distance of the impact point from the centre of rotation
of d ¼ 0:5 and 0.3 m respectively, produces the follow-
ing diagram (Fig. 11).
Investigation was further carried out on the size dis-
tribution of the fragmentation using a PFC3D model of
rock sample with cubical shape comprising 343 balls
(6 mm diameter). The size of the cube was 42 mm. Balls
bond strength was kept constant. The speed of the
crusher varied in the range 800–1000 rpm. It was ob-
served that the intensity of fragmentation was a function
of the rotational speed of the impeller. For low rota-
tional speeds, fragmentation initially did not occur until
it impacts on the crusher anvil. Forces induced into the
crusher anvil were always higher than that induced from
the impacting impeller. As speed of the impeller in-
creases, initial impact becomes a significant cause of
fragmentation. These effects are demonstrated in Fig.
12.
5. Conclusions
The DEM technique provides estimates that consider
single particles and some particle interactions in the
impact crushers. The distribution of collision energies
can be converted into a product size distribution for a
particular ore type using impact breakage test data. The
PFC3D code has been applied to two types of impact
crusher: the industrial-scale vertical shaft impact crusher
and the pilot-scale horizontal shaft swing hammer mill.
Upon the DEM procedures being validated, a de-
tailed simulation study has been conducted to investi-
gate the effects of the machine design and operational
conditions on velocity and energy distributions of col-
lision inside the milling chamber. Analytical modelling
of rock fragmentation has also been attempted using a
strain rate concept.
0
5
10
15
20
25
0 500 1000 1500 2000 2500 3000 3500
Rotational speed (rpm)
Meanfragmentsize(mm)
d = 0.3 m
d = 0.5 m
Fig. 11. The influence of the rotational speed on the impact-induced
mean fragment size at two different impact positions (initial rock size
L ¼ 0:1 m).
0
20
40
60
80
100
0 10 20 30 40
Fragment diameter (mm)
Cum.wt%passing
1000 rpm
900 rpm
800 rpm
0
20
40
60
80
100
0 10 20 30 40
Fragment diameter (mm)
Cum.wt%passing
1000 rpm
900 rpm
800 rpm
(a) (b)
Fig. 12. Fragment size distributions created by different breakage mechanisms. (a) Impacted by the impellers, (b) impacted by the impellers and
crusher anvils.
990 N. Djordjevic et al. / Minerals Engineering 16 (2003) 983–991

9. The results show that DEM can be used to model the
particle flow behaviour, energy utilisation and product
size in the impact crushers, and thus assist in machine
and process design.
Acknowledgements
The authors wish to acknowledge the assistance of
Dr. Toni Kojovic in providing the breakage data that
were used for the Canica crusher modelling. The data of
the BJD hammer mill were from ACARP Project
C8057, for which the financial support from ACARP
and BHP-Billiton Port Kembla steelworks is greatly
appreciated. Useful discussions with Dr. Peter Cundall
of ITASCA are acknowledged. The work was funded by
the JKMRC.
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