The document outlines the concept and operational principles of roller presses, highlighting their role in grinding and pyro-processing. It details specifications, key parameters, and advantages of roller presses, including energy savings and enhanced grinding efficiency. Additionally, it compares different modes of operation regarding capacity increase, energy savings, and maintenance costs.

1. ROLLER PRESS
(HIGH PRESSURE GRINDING
ROLLS)
V Naga Kumar
STRENGTHENING CAPABILITIES IN PYRO-PROCESSING & GRINDING
NATIONAL COUNCIL FOR CEMENT & BUILDING MATERIALS
BALLABGARH (HARYANA)

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3. What is Roller Press ?
Originally a compaction tool rather than a grinder
Mainly as a pre-grinder for Capacity increase
Integral Grinding with a high recirculation rate
Applies the concept of high pressure transfer
through a bed of material
Pressure across the bed has a compacting effect
on material which is crushed and gradually reduces in
size
Stability ensured by uniform feed control
Can be utilized in various configurations
Energy saving: substitution rate w.r.t. Ball Mill: 1.5~2.5
kWh/t 3

4. Principle of roller press
• The compaction of the
material with the
density ρ start at the nip
angle αo. The maximum
is achieved at the so
called attack angle β(
center of pressure)
where the material
reaches the slab density
ρG.
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5. • High grinding pressure between 50 and 400 MPa
• Roller circumferential speed 0.5 to 1.8 m/s
• Feed grain size up to 60 mm
• Compacted cakes contain up to 40 % fines (< 90 µm)
• Compacted cakes contain also coarser particles with large
numbers of cracks and weak points
• Reduce energy during further grinding
Specifications of roller press
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6. Operating principle
In high-pressure roller press comminution
The feed material is exposed to very high pressure for a short
time.
The high pressure causes formation of micro cracks in the feed
particles and generates a substantial amount of fine material.
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7. Feed is nipped into the gap as a result of opposite rotation;
Material Commuted, compacted & shaped -
Into slabs / flakes /cakes
Different operations proceed simultaneously:
 Density increases from 1.6 to 2.4 t/Cu.m
 Expelling most of the air contained in the feed
 Interparticle communition
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Feed to product

8. Key Parameters of Roller press
• Press throughput
M= W x S x V x ρ x 3.6 t/h
1000
M = Press through put t/h
S = Slab thickness mm
V = Circumferential speed m/s
ρ = Density of slab t/m3
for clinker 2.4 – 2.5 t/m3
for raw material 2.3 – 2.4 t/m3
for slag 2.2 – 2.3 t/m3
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9. Key Parameters of Roller press
• Roller force
M= d/1000 2x л x Z x P x 100/4 KN
d = diameter hydr cylinder mm
Z = Number hydr cylinders
P = Hydraulic pressure (b)
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10. Key Parameters of Roller press
• Absorbed motor power at counter
P= 2 x F x β x V kW
η
F = Press Force k/N
η = Efficiency gear and motor
β = Attack angle 0
for clinker 2.3 – 2.85 0
for raw material 2.85 – 4 0
for slag 1.7 – 2.3 0
V = Circumferential speed m/s
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11. Circulating load factor [-]
Roller speed [m/s]
Stable operation
unstable operation
 Maximize absorbed power by increasing circulating load close to
point of unstable operation
Maximizing Absorbed Power
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12. Key Parameters of Roller press
• Specific roller pressure
K = F x 106 kN/m2
D x W
k ≤ 6000 kN/m2
W = Roller width mm
D = Roller diameter mm
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13. Key Parameters of Roller press
• Specific surface load
L= F x 103 N/mm2
W x D/2 X α
F = Press force k/N
W = Roller width mm
D = Roller diameter mm
α = Nip angle 0
for clinker 6.9 – 9.2 0
for raw material 9.2 – 12.6 0
for slag 5.7 – 7.5 0 13

14. Key Parameters of Roller press
• Specific energy consumption
E = P/M kWh/t
P = Abs motor power kW
M = Press throughput t/h
for clinker 2.5 – 3 kWh/t
for raw material 2 – 2.5 kWh/t
for slag ~ 3 kWh/t
Ec = P U /M kWh/t
Ec = Closed circuit ( with separator or/and slab
recirculation)
U = Circulation factor 14

15. Communition in roller press
• Increases with rising pressure , but only little
beyond an optimum level ,as after reaching
that level of compression cake behaves as non
compressible, viscous fluid
• Closely graded material requires high pressure
as more voids present
• Widely graded requires less as less void
present
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16. Material layer
• Material layer above roller gap gives efficient
comminution
• Feed bin above roller gap serves as buffer to avoid
feed fluctuation
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17. Material hardness
Material hardness is reduced if processed
through roller press, help in grinding hard
material
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18. Feed size
For a gap width of 25 mm, material size
around 100 mm can be processed
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19. Roller diameter
• Cake thickness changes proportional to roller
diameter and roller thickness
• Cake thickness can be changed by narrowing
nipping area of roller too
• Nipping area can be changed by modifying roller
surface too
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20. Roller press advantages
• Long wear part life
• Low operational and maintenance costs
• Short shutdown for wear part
• Replenishment
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21. Roller press cake quality
• Raw Grinding 2.2 to 2.3 MT / M3
• Finish grinding 2.6 MT/ M 3
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22. CONFIGURATION FOR ROLLER PRESS CIRCUITS
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23. Comparative performance in different
modes of operation
MODE OF
OPERATION
CAPACITY
INCREASE,
%
ENERGY
SAVING,%
MAINTEN-
ANCE
COST %
INVESTMENT
COST,%
PRE-
GRINDING
25-40 10-20 105 90-110
HYBRID-
GRINDING
50-70 20-30 110 90-110
COMBI-
GRINDING
80-200 25-45 130 130
FINISH-
GRINDING
--- 40-60 120 100
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