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1 Single Particles in a Fluid1

1.1 Motion of Solid Particles in a Fluid1

1.2 Particles Falling Under Gravity Through a Fluid3

1.3 Non-spherical Particles5

1.4 Effect of Boundaries on Terminal Velocity5

1.5 Further Reading7

1.6 Worked Examples7

Exercises17

2 Multiple Particle Systems19

2.1 Settling of a Suspension of Particles19

2.2 Batch Settling21

2.2.1 Settling Flux as a Function of Suspension Concentration21

2.2.2 Sharp Interfaces in Sedimentation23

2.2.3 The Batch Settling Test24

2.2.4 Relationship between the Height-Time Curve and the Flux Plot26

2.3 Continuous Settling29

2.3.1 Settling of a Suspension in a Flowing Fluid29

2.3.2 A Real Thickener（with Upflow and Downflow Sections）31

2.3.3 Critically Loading Thickener32

2.3.4 Underloaded Thickener33

2.3.5 Overloaded Thickener33

2.3.6 Alternative Form of Total Flux Point34

2.4 Worked examples35

Exercises47

3 Particle Size Analysis55

3.1 Introduction55

3.2 Describing the Size of a Single Particle55

3.3 Description of Populations of Particles58

3.4 Conversion Between Distributions60

3.5 Describing the Population by a Single Number60

3.6 Equivalence of Means62

3.7 Common Methods of Displaying Size Distributions64

3.7.1 Arithmetic-normal Distributions64

3.7.2 Log-normal Distribution65

3.8 Methods of Particle Size Measurement66

3.8.1 Sieving66

3.8.2 Microscopy66

3.8.3 Sedimentation66

3.8.4 Permeametry68

3.8.5 Electrozone Sensing68

3.8.6 Laser Diffraction69

3.9 Sampling70

3.10 Worked Examples70

Exercises79

4 Fluid Flow Through a Packed Bed of Particles81

4.1 Pressure Drop-flow Relationship81

4.1.1 Laminar Flow81

4.1.2 Turbulent Flow83

4.1.3 General Equation for Turbulent and Laminar Flow83

4.1.4 Non-spherical Particles84

4.2 Filtration85

4.2.1 Introduction85

4.2.2 Incompressible Cake85

4.2.3 Including the Resistance of the Filter Medium86

4.2.4 Washing the Cake87

4.2.5 Compressible Cake88

4.3 Further Reading89

4.4 Worked Examples89

Exercises93

5 Fluidization97

5.1 Fundamentals97

5.2 Relevant Powder and Particle Properties100

5.3 Bubbling and Non-bubbling Fluidization101

5.4 Classification of Powders102

5.5 Expansion of a Fluidized Bed107

5.5.1 Non-bubbling Fluidization107

5.5.2 Bubbling Fluidization108

5.6 Entrainment110

5.7 Heat Transfer in Fluidized Beds115

5.7.1 Gas-Particle Heat Transfer115

5.7.2 Bed-Surface Heat Transfer116

5.8 Application of Fluidized Beds119

5.8.1 Physical Processes119

5.8.2 Chemical Processes120

5.9 A Simple Model for the Bubbling Fluidized Bed Reactor122

5.10 Some Practical Considerations127

5.10.1 Gas Distributor127

5.10.2 Loss of Fluidizing Gas127

5.10.3 Erosion128

5.10.4 Loss of Fines128

5.10.5 Cyclones128

5.10.6 Solids Feeders129

5.11 Worked Examples129

Exercises134

6 Pneumatic Transport and Standpipes139

6.1 Pneumatic Transport139

6.1.1 Dilute Phase and Dense Phase Transport140

6.1.2 The Choking Velocity in Vertical Transport140

6.1.3 The Saltation Velocity in Horizontal Transport142

6.1.4 Fundamentals143

6.1.5 Design for Dilute Phase Transport147

6.1.6 Dense Phase Transport152

6.1.7 Matching the System to the Powder158

6.2 Standpipes159

6.2.1 Standpipes in Packed flow160

6.2.2 Standpipes in Fluidized Bed Flow160

6.2.3 Pressure Balances During Standpipe Operation163

6.3 Further Reading166

6.4 Worked Examples166

Exercises172

7 Separation of Particles from a Gas：Gas Cyclones175

7.1 Gas Cyclones-description176

7.2 Flow Characteristics177

7.3 Efficiency of Separation177

7.3.1 Total Efficiency and Grade Efficiency177

7.3.2 Simple Theoretical Analysis for the Gas Cyclone Separator178

7.3.3 Cyclones Grade Efficiency in Practice181

7.4 Scale-up of Cyclones181

7.5 Range of Operation182

7.6 Some Practical Design and Operation Details185

7.6.1 Effect of Dust Loading on Efficiency185

7.6.2 Cyclone Types185

7.6.3 Abrasion185

7.6.4 Attrition of Solids186

7.6.5 Blockages186

7.6.6 Discharge Hoppers and Diplegs186

7.6.7 Cyclones in Series187

7.6.8 Cyclones in Parallel187

7.7 Worked Examples187

Exercises191

8 Storage and Flow of Powders-Hopper Design193

8.1 Introduction193

8.2 Mass Flow and Core Flow193

8.3 The Design Philosophy196

8.3.1 Flow-No Flow Criterion197

8.3.2 The Hopper Flow factor ff197

8.3.3 Unconfined Yield Stress，σy197

8.3.4 Powder Flow Function198

8.3.5 Critical Conditions for Flow198

8.3.6 Critical Outlet Dimension199

8.3.7 Summary200

8.4 Shear Cell Tests200

8.5 Analysis of shear cell test results202

8.5.1 Mohr’s Circle-in Brief202

8.5.2 Application of Mohr’s Circle to Analysis of the Yield Locus202

8.5.3 Determination of σy and σc203

8.5.4 Determination of δ from Shear Cell Tests204

8.5.5 The Kinematic Angle of Friction Between Powder and Hopper Wall205

8.5.6 Determination of the Hopper Flow Factor206

8.6 Summary of Design Procedure209

8.7 Discharge Aids210

8.8 Pressure on the Base of a Tall Cylindrical Bin210

8.9 Mass Flow Rates213

8.10 Conclusions213

8.11 Worked Examples214

Exercises217

9 Mixing and Segregation223

9.1 Introduction223

9.2 Types of Mixture223

9.3 Segregation224

9.3.1 Causes and Consequences of Segregation224

9.3.2 Mechanisms of Segregation225

9.4 Reduction of Segregation229

9.5 Equipment of Particulate Mixing230

9.5.1 Mechanisms of Mixing230

9.5.2 Types of Mixer230

9.6 Assessing the Mixture232

9.6.1 Quality of a Mixture232

9.6.2 Sampling232

9.6.3 Statistics Relevant to Mixing232

9.7 Worked Examples235

Exercises239

10 Particle Size Reduction241

10.1 Introduction241

10.2 Particle Fracture Mechanisms241

10.3 Model Predicting Energy Requirement and Product Size Distribution245

10.3.1 Energy Requirement245

10.3.2 Prediction of the Product Size Distribution249

10.4 Types of Comminution Equipment250

10.4.1 Factors Affecting Choice of Machine250

10.4.2 Stressing Mechanisms251

10.4.3 Particle Size256

10.4.4 Material Properties257

10.4.5 Carrier medium258

10.4.6 Mode of operation258

10.4.7 Combination with Other Operations258

10.4.8 Types of Milling Circuit259

10.5 Worked Examples260

Exercises263

11 Size Enlargement267

11.1 Introduction267

11.2 Interparticle Forces268

11.2.1 Van der Waals Forces268

11.2.2 Forces due to Absorbed Liquid Layers268

11.2.3 Forces due to Liquid Bridges268

11.2.4 Electrostatic Forces269

11.2.5 Solid Bridges270

11.2.6 Comparison and Interaction between Forces270

11.3 Granulation271

11.3.1 Introduction271

11.3.2 Granulations Rate Processes271

11.3.3 Simulation of the Granulation Process275

11.3.4 Granulation Equipment279

12 Fire and Explosion Hazards of Fine Powders283

12.1 Introduction283

12.2 Combustion Fundamentals284

12.2.1 Flames284

12.2.2 Explosions and Detonations284

12.2.3 Ignition，Ignition Energy，Ignition Temperature-a Simple Analysis284

12.2.4 Flammability Limits287

12.3 Combustion in Dust Clouds289

12.3.1 Fundamentals Specific to Dust Cloud Explosions289

12.3.2 Characteristics of Dust Explosions289

12.3.3 Apparatus for Determination of Dust Explosion Characteristics290

12.3.4 Application of the Test Results292

12.4 Control of the Hazard293

12.4.1 Introduction293

12.4.2 Ignition Sources294

12.4.3 Venting295

12.4.4 Suppression296

12.4.5 Inerting296

12.4.6 Minimise Dust Cloud Formation296

12.4.7 Containment296

12.5 Worked Examples297

Exercises299

Notation301

References309

Index315