Dust control handbook

1. DUST AND ITS CONTROL 1 What Is Dust? 1 How Is Dust Generated? 1 Types of Dust 2 Respirable Dust 2 Inhalable Dust 3 Total Dust 3 Why Is Dust Control Necessary? 3 Health Hazard Factors 4 How Is Dust Controlled? 5 Prevention 5 Control Systems 5 Dilution-Isolation 6 2. PREVENTING DUST FORMATION 7 Introduction 7 Belt Conveyors ' 8 Types of Belt Conveyors 8 Emission Points 8 Dust Prevention Measures 9 Transfer Chutes 11 Dust Prevention Measures 11 Enclosures 13 Dust Prevention Measures 13 Crushers ..........•......................................................14 Types of Crushers 14 Emission Points 15 Dust Prevention Measures 15 Screens 16 Types of Screens ...•.....................................................16 vii viii Contents Emission Points 17 Dust Prevention Measures ......•••.••••.•.•...........•..•....••.•.••...•..17 Storage Bins and Hoppers ..............•.................•.........•.....••..17 Emission Points.•...•..............•.....................................18 Dust Prevention Measures .......•...............................•..........18 Bucket Elevators .•.....•...............•........................•..•.......19 Types of Bucket Elevators....•...•..•...........•.•..........•......••.••..19 Emission Points........•.•..•........•.....................••....•.••••..19 Dust Prevention Measures •.....................................•.....•.•...19 Feeders ........•...••..•...••......•.....................................20 Types of Feeders....•••............•........•..•.............•...........20 Emission Points............•..•.•••.•...••..............•....•••.•...•.••.21 Dust Prevention Measures •...•....................•........................21 Screw Conveyors ..............•.•...............................•..•.......21 Emission Points............•...........................•.................21 Dust Prevention Measures ......................................•...........21 Pneumatic Conveyors ..•.......•............................................22 Emission Points........••...................................•••..........22 Dust Prevention Measures ..••.....•........................................22 Grinding Mills .................•...........................................23 Emission Points.......................................•.•........••......23 Dust Prevention Measures .....................................••...........23 Dryers , " 23 Emission Points........................•.......•............•........•...24 Dust Prevention Measures ...............................••.•..•............24 Stockpiles ......................................•.....•.....•.............24 Emission Points........................•.................................25 Dust Prevention Measures ...........•.........•..............•.............25 Haul Roads ..........................................•...........•.•..•.•.26 Emission Points....................................................•.....26 Dust Prevention Measures .•.......•.••••........................•....••.••.26 '!'ruck and Railroad Car Dumping ..•.•.....••..................................27 Emission Points..•.........•...............................•...........•.27 Dust Prevention Measures ....•...................•.•......•.•.....•.....••.27 Powder Handling and Packing ...•.......••........•...................•..•....28 Bagging .....•...•...••.....•..........•.......••....................•..28 Barrel or Drum Filling.......•......•.................................•....29 Emission Points. : ..•..•..................................................29 Dust Prevention Measures .......•...........•.................•............30 3. DUST CONTROL SYSTEMS .......•...........................................33 Why Dust Control? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Types of Dust Control Systems 34 Selection of a Dust Control System............................••.....•.....•...34 Dust Collection Systems .........•..................................•.....•..35 Principles of Airflow ..•.......•.•........•..•.•.......••...•........•..•.•36 Exhaust Hood ....•......•...............•...........•..••..•........•..•37 Ductwork ...•......................•......•............................43 Wet Dust Suppression Systems ...............................•...•....•.......54 Factors Affecting Surface Wetting.....................................•......54 Types of Wet Dust Suppression Systems •....................................•.55 Contents ix Airborne Dust Capture Systems 57 Factors Affecting Collision 57 Types of Airborne Dust Capture Systems 58 Design of a Water-Spray System 58 Water Flow and Compressed Airflow Rates 61 Piping Design 61 Instruments 62 Pump and Compressor Selection 62 4. COLLECTING AND DISPOSING OF DUST 63 What Is a Dust Collector 63 Necessity for Dust Collectors 63 Types of Dust Collectors 63 Types of Inertial Separators 64 Fabric Collectors 69 How They Work 69 Types of Baghouses 70 Wet Scrubbers 80 Types of Scrubbers 81 Electrostatic Precipitators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87 Types of Precipitators ...............................•.....................88 Unit Collectors 90 selecting a Dust Collector 91 Fan and Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94 Types of Fans 94 Fan Selection 95 Fan Installation 97 Electric Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98 Types of Motors 98 Selection of Motor 99 Disposal of Collected Dust 104 Removing Dust from Hopper 104 Conveying the Dust 104 Storing the Dust ..............................•.........................105 Treating the Dust for Final Disposal 105 5. SPECIFIC ILLU5TRATIONS 107 6. ESTIMATING COSTS OF DUST CONTROL SYSTEMS 147 Necessity for Cost Estimates 147 Cost Estimating Procedures 147 Cost Components 148 Capital Costs 148 Operating and Maintenance Costs 152 Cost Justification 155 7. CONTROLLING SURROUNDING DUST SOURCES 157 Introduction 157 Contributing Sources/Factors 157 Administrative Measures 158 Preventive Maintenance Program 160 x Contents Proper Operating Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . .161 Managerial Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . .162 Outside Dust Source Control. 162 Recirculation of Uncontrolled Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~. . . . .163 8. SAMPLING DUST IN THE WORK ENVIRONMENT 167 Personal Dust Sampling 167 ABC's of Personal Dust Sampling 168 Threshold Limit Value (TLV) 169 Time-Weighted Average (TWA) .................................•...........169 Personal Dust Sampling Equipment......................................•.....169 Cyclone 170 Filter-Cassette Assembly 170 Sampling Pump 171 Sampling Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171 In Office 171 In Field ....................•..........................................171 Errors in Respirable Dust Sampling 174 9. TESTING DUST CONTROL SYSTEMS 177 Reason for Testing 177 Dust Collection System Testing 177 Test Procedure 178 Airflow Measurements 178 Wet Dust Suppression 181 Test Procedure ........................................•................181 Evaluating Dust Control Systems 185 Types of Samples 185 Sampling Locations 185 Sampling Instrumentation 186 Sampling Approaches 186 Data Collection 187 Data Analysis ..........................•...............................187 BIBLIOGRAPHY 189 INDEX 199