Characterization of the Centrifugal Mill

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• Characterization of the Centrifugal Mill
• by Lumped Kinetic Math Model and Discrete Element
  Model
• T. Inoue and K. Okaya
• Department of Earth System Engineering,
• University of Tokyo

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Centrifugal Mill
Eccentricity Acceleration Coefficient
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Force balance in centrifugal mill (Bradley et al.)
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Theoretical Model (Bradley et al.)
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Upper limit of phase angle (theoretical)
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Mill Solver - A 2-D DEM Model -1
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Mill Solver - A 2-D DEM Model -2
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Mill Solver - A 2-D DEM Model -3
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Effect of mill diameter (D) on mill power,
determined by DEM simulation.
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Effect of ball density on mill power, determined
by DEM simulation
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Effect of centrifugal coefficient (z) on mill
power and energy consist,determined by DEM
simulation -1
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Effect of centrifugal coefficient (z) on mill
power and energy consist,determined by DEM
simulation -2
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Effect of eccentricity (G/D) on mill power,
determined by DEM simulation
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Effect of ball filling (J) on power draft,
determined by DEM simulation
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Effect of eccentricity (G/D) on energy
dissipation pattern
Energy Consist
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Effect of friction coefficient and restitution
coefficient on power draft -1
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Effect of friction coefficient and restitution
coefficient on power draft -2
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Effect of Restitution Coefficient on Power
Dissipation
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Weighted density distribution of energy spectrum
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Theoretical (Bradley et al.)
DEM simulation (Inoue-Okaya)
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Specification of prototype X-Mill
Type Double cylinder self- balancing
centrifugal mill Mill Operation Batch or
continuos Dimension of 150 mm dia. Mill
cylinders 300 mm length Eccentricity
(G/D) 0.2 Grinding media 17 kg (for steel
balls) Equipment size 762 (W) 935 (H)
1190 (L) mm Motor 7.5 kW
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X-Mill
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X-Mill (prototype)
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X-Mill (prototype) in motion
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Batch grinding (quartz)
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Continuous grinding (quartz)
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Autogenous grinding (limestone)
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Figure 2. Phase angle of the centrifugal mill
estimated from math model.
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Figure 3. Net power draft of the centrifugal mill
estimated from math model
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Figure 4. Phase angle of the centrifugal mill
estimated from math and simulator models.
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Figure5. Net power draft of the centrifugal mill
estimated from math and simulator models.
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Conclusion

• Theoretical model can present approximate but
  clear view of the equipment property in the
  form of a simple equation
• DEM simulation can present a more realistic
  vision of the equipment and its performance
• DEM simulation can present the property of
  the possible mill design under less
  restriction and less expenses
• DEM simulation gives a microscopic view of
  the comminution events together with their
  integral effects in realistic figures