4 slides on silos and granular solids research

							Granular solids research

                 Jin Ooi

Institute for Infrastructure & Environment
           School of Engineering
          University of Edinburgh
              Granular solids
                               • Granular solids are
                                 everywhere!
                               • Over 75% of raw
                                 materials in industry are
                                 granular
 landslides     Snow avalanche
                               • Handling and processing
                                 of granular solids are
                                 widespread in many
                                 industries
                               • 40% of capacity in
                                 industrial plants is
                                 wasted because of
                                 granular solid problems
                                 (Ennis et al, 1994)

Industrial bulk solids handling
Silo failures are quite common. Each year,
over 1000 silos and hoppers fail in North
America alone (Knowlton et al)
           Research focus
• Fundamental research on granular solids
  and structures
• Applications in industrial infrastructure such
  as silos and bulk handling problems
• Novel multidisciplinary approach to address
  challenging industrial and scientific
  problems
• A few examples …
   Arching and ratholing problems
     are widespread in industry




Cohesive arch   Rathole
    Novel testers to assess handlability of
     sticky industrial solids and powders




  Edinburgh Cohesion
  Tester for coal testing
Licensed to Ultradynamics,                         EPT powder tester for
        Australia                                     DuPont USA:
                                                   commercial prototype

                             Large Automated ECT
        Flow and pressure in silos
• Mechanics of granular solids flow
• Pressures in flowing solids in silos
• Strength and design of silo structures




Silo design for LKAB Ltd: 10 x 40m diameter silos
for storing ~1 million tonnes of iron ore pellets in Narvik
  DEM research
 Discrete Element Method is an increasingly
  popular computational technique
 models the motion and interaction of individual
  particles
 models interaction with machinery surfaces
  and interstitial fluids
 Edinburgh spin-out company DEM Solutions
  Ltd providing state-of-the-art EDEM software
 DEM as a multi-scale computational tool

 Mixing dynamics
                          Macro-scale information
                                                                      Segregation
Uniformity of flow
                                                                    Mixing efficiency
                               Particle-scale data
                                 Spatial position                         Flow behaviour
Conductive heat
                         Translation & Rotational Velocity                   Jamming
   transfer
                     No.of contacting particles Contact history         Shear rate gradients
 Mass transfer
 Hold-up                  Particle size/mass/temperature
                       Particles contacting machine surfaces             Granulation
Comminution
                            Contact forces Drag forces                  Agglomeration
 Mechanical
   energy                       Electrostatic forces                   Surface coating
consumption
     Attrition                                                      Particle-machine
                                                                  interaction dynamics
 Damage/breakage            Fluidisation
                            phenomena
                        Pneumatic transport
             Scientific validation of DEM




   Particle filling   Discharge through an outlet        Rotating drum




                                                    Direct shear testing
Confined compression       Rod penetration
  Case Study: VR Steel
                                                     www.vrsteel.co.za

The quest for reduced operating costs
  – Reduce equipment mass and retain or improve performance




   Truck load body mass= 34 ton       Dragline bucket mass= 43 ton
         Payload = 230 ton                  Payload = 106 ton

       Source:
  Case Study: VR Steel Load body
                                         www.vrsteel.co.za
• Load body mass reduction of
  20%
   – Less dead mass to haul, less fuel
   – Less power required to tip, less
     fuel
• Improved shape
   – Reduced unloading time, less fuel
• Overall performance
  improvement




             Source:
         Belt Loading on Transfer Point
                            Comparison of Pressure across
                                       Belts
                    16000
                    14000
  Pressure (N/m2)




                    12000
                    10000
                     8000
                                                                              Belt 1 (X)
                     6000
                                                                              Belt 2 (Y)
                     4000
                     2000
                        0
                            0   200     400      600     800    1000   1200
                                      Position across Belt (mm)




Aim to obtain even loading distribution on the belt
                Wear Analysis
• Implementation of Archard wear model
• Analyse effects of different parameters on the
  level of wear on the machine




      Source:
  PARDEM European project
• cohort of 15 highly interactive projects,
  led by Edinburgh University
• collaboration with universities and
  industries
• to train top class DEM researchers          P&G
• To develop best practice methodologies
  in DEM calibration and validation
Thank you for your attention!