Dust Control Handbook for Industrial Minerals Mining and Processing

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High-volume, high-pressure sprays should be avoided. The energy of the spray transfersto the material particles, resulting in more dust production [Goldbeck and Marti 2010].The amount of moisture applied should be varied and tested at each operation todetermine the optimum quantity, but a one percent moisture to product ratio is a goodstarting point. Excess moisture can promote slippage and adversely affect conveyor beltperformance in cold weather conditions.Some studies indicate that wetting the return side of the conveyor belt also helps tominimize dust liberation. This practice reduces dust generation from the idlers as well asat the belt drives and pulleys.Water sprays located on the top (wetting the product) and the bottom (reducing dust fromthe idlers) at the same application point can be a very effective strategy [Courtney 1983;Ford 1973]. These locations are also beneficial from an installation and cost standpoint.Fan spray nozzles are the most commonly used because they minimize the volume ofwater added for the amount of coverage. It is more advantageous to locate the watersprays at the beginning of the dust source (i.e., the dump or transfer location) because asthe water and ore continually mix together, the wetted surface of the ore grows involume, increasing the suppression potential and reduction in dust liberation.Using more spray nozzles at lower flow rates and positioning them at locations closer tothe ore is more advantageous than using fewer sprays at higher flow rates [NIOSH 2003].Suppression of airborne dust involves the application of water, either untreated or chemicallytreated, in the form of spray, fog, or foam to prevent the dust fines from escaping into the air.Fog and foam are less used than water application alone, in particular because of the potentiallyhigher costs and chemical contamination issues.SCREW CONVEYORSScrew conveyors are one of the oldest and simplest methods for moving bulk materials(Figure 5.17). They consist of a conveyor screw rotating in a stationary trough. Material placedin the trough is moved along its length by rotation of the screw. Screw conveyors can bemounted horizontally, vertically, and in inclined configurations.Figure 5.17. Depiction of a typical screw conveyor.Conveying and Transport 147
Normally, screw conveyors are totally enclosed except at the ends, where dust emissions can becontrolled by proper transfer chute design. The screw conveyor cover is usually fastened by nutsand bolts. However, to maintain a proper dust seal, a self-adhesive neoprene rubber gasketshould be installed.Screw conveyors are essentially dust- and spillage-free as long as the casings, packing glands,and transfer chutes are properly designed and maintained. The only location where spillagetypically may occur is where the screw shaft exits the screw conveyor housing. Pedestalmountedpillow block support bearings (Figure 5.18) should be used and mounted outside thecasing. Packing gland seals can be installed where the shaft exits the casing and before thebearing. This will prevent spillage and protect the bearings.Figure 5.18. Packing gland and pillow block support bearing.BUCKET ELEVATORSA typical bucket elevator (Figure 5.19) consists of a series of buckets mounted on a chain or beltthat operates overhead and tail pulleys. The buckets are loaded by scooping up material from theboot (bottom) or by feeding material into the buckets. Material is discharged as the bucketpasses over the head pulley.148 Conveying and Transport
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Report of Investigations 9689Dust C
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FUNDAMENTALS OF DUSTCOLLECTION SYST
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Minimizing Field Fits and Welds ...
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Recommendations for Proper Wet Dril
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CONTROL TECHNOLOGIES FOR FILLING 50
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Effective Filtration ..............
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ILLUSTRATIONSFigure 1.1. Relationsh
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Figure 3.2. The air and water flow
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Figure 9.5. Problem created by heat
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UNIT OF MEASURE ABBREVIATIONSUSED I
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Robert J. Franta, Quotation Enginee
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silica. Quartz is the most common s
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DUST CONTROL HANDBOOK FOR INDUSTRIA
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CHAPTER 1: FUNDAMENTALS OFDUST COLL
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The shape of particles affects how
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EXHAUST SYSTEMS DESIGNAll exhaust s
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stripping, which allows workers to
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When using the air quantities in Ta
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X = distance in feet from the face
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Checklist for Hood EffectivenessThe
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A major disadvantage of the high-ve
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A common misconception when designi
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Avoiding Mitered Elbows Greater Tha
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Figure 1.13. Depiction of the horiz
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Figure 1.14. Typical design of grav
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Baghouse CollectorsBaghouse dust co
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Table 1.2. Emission factors for cru
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Figure 1.17. Typical design of a me
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Reverse Jet (Pulse Jet) CollectorsR
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Figure 1.20. Cartridge collector wi
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Wet scrubbers are particularly adva
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Electrostatic precipitators normall
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may be related to specific applicat
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times. When considering the depth o
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Figure 1.25. Demonstration of how a
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Figure 1.26. A typical fan performa
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Fan TypesThere are two basic types
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Figure 1.30. Typical centrifugal fa
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Figure 1.32. Typical roof ventilato
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The vast majority of dust particles
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Table 2.1. Particle/droplet size in
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Air Atomizing NozzlesAir atomizing
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Hydraulic Flat Fan NozzlesFigure 2.
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for dust knockdown or suppression,
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Nozzle MaintenanceFigure 2.14. Typi
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Accidental DamageInadvertent harm t
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NDT Educational Resource Center, Io
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78 Wet Spray SystemsDUST CONTROL HA
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contains a piston which delivers ha
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produce an increase in the penetrat
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Dry DrillingDry drilling is accompl
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Circular ShroudIn contrast to the u
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The collector airflow has a more su
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Air-Blocking ShelfThe air-blocking
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dust emissions from mast lowering,
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This simple procedure of creating a
Page 125 and 126: Figure 3.15. Air ring seal used to
Page 127 and 128: Figure 3.17. Illustrations showing
Page 129 and 130: unsubstantiated due to the inconsis
Page 131 and 132: safety considerations may preclude
Page 133 and 134: Figure 3.22. A filtration unit, loc
Page 135 and 136: Miller S, Emerick JC, Vogely WA [19
Page 137 and 138: USBM [1995]. The reduction of airbo
Page 139 and 140: 110 Drilling and BlastingDUST CONTR
Page 141 and 142: Wet Control MethodsPREVENTION AND S
Page 143 and 144: Figure 4.2. Examples of compressive
Page 145 and 146: Figure 4.5. Illustration of a dry (
Page 147 and 148: Figure 4.6. Illustration of a dry (
Page 149 and 150: Wet dust control methods for crushi
Page 151 and 152: Work Practices to Minimize Dust Exp
Page 153 and 154: Some specialty grinding operations
Page 155 and 156: should be frequently inspected for
Page 157 and 158: Open screen decks slowly to allow i
Page 160 and 161: DUST CONTROL HANDBOOK FOR INDUSTRIA
Page 162 and 163: CHAPTER 5: CONVEYING AND TRANSPORTT
Page 164 and 165: Figure 5.3. Basic depiction of mate
Page 166 and 167: that the material falls before land
Page 168 and 169: Figure 5.10. Skirtboard used within
Page 170 and 171: CarrybackMaterial that sticks or cl
Page 172 and 173: CONVEYOR DESIGN AND MAINTENANCE ISS
Page 174 and 175: Figure 5.15. Conveyor transfer encl
Page 178 and 179: Figure 5.19. Depiction of a bucket
Page 180 and 181: Figure 5.21. Depiction of two types
Page 182 and 183: Figure 5.25. Venturi eductor utiliz
Page 186 and 187: CHAPTER 6: BAGGINGThis chapter disc
Page 188 and 189: caused during manufacturing, includ
Page 190 and 191: Overall PerforationsThe use of over
Page 192 and 193: Figure 6.5. Open-top bag being load
Page 194 and 195: Bagging operators should be aware t
Page 196 and 197: Figure 6.8. Exhaust hood to capture
Page 198 and 199: In the original design, a single no
Page 200 and 201: The OASIS is a relatively simple de
Page 202 and 203: Figure 6.13. Bag storage shelves sh
Page 204 and 205: Figure 6.14. Bag and belt cleaner d
Page 206 and 207: other industrial application using
Page 208 and 209: The robotic arm automatic palletize
Page 210 and 211: For many years, this plastic wrappi
Page 212 and 213: warehouse location until a later ti
Page 214 and 215: used successfully to perform this c
Page 218 and 219: CHAPTER 7: BULK LOADINGDuring the b
Page 220 and 221: Figure 7.2. Loading spout discharge
Page 222 and 223: Cascading Loading SpoutFigure 7.5 i
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REFERENCESBiere G, Swinderman RT, M
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200 Bulk LoadingDUST CONTROL HANDBO
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many years, as well as some new and
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Figure 8.2. Air spray manifold desi
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Figure 8.3. Test subject wearing po
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Spills of product material are a co
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epetitive dust leaks should not sim
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Effective Upward Airflow PatternThe
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Figure 8.8. Open-structure design c
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manually removing the bags and plac
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Figure 8.12. Increase in worker’s
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In other cases, an operation may wa
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Cecala AB, O'Brien AD, Pollock DE,
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224 Controls for Secondary SourcesD
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where C o = outside respirable dust
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minimal improvement in the cab's ai
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RECOMMENDATIONS FOR FILTRATION/PRES
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Effective FiltrationFigure 9.4. Res
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average decay times were between 16
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Figure 9.6. Filtration unit showing
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This table highlights a number of c
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NIOSH [2001b]. Technology news 486:
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upon the wind velocity (or disturba
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Maximum size is the largest particl
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Figure 10.4. Use of end-dumping wit
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conditions. Performance of each of
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A water truck, used to apply water
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Surfactants work by reducing the su
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which differed for the various site
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Figure 10.9. Self-tarping dump truc
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percent [Fryrear and Skidmore 1985]
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Figure 10.12. The armoring process
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A current method of stockpile forma
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Figure 10.15. Demonstration of how
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Chekan GJ, Cecala AB, Colinet JF [2
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Midwest Research Institute [1981].
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GLOSSARYAbrader. An implement used
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Carryback. Material that sticks or
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End-dumping. A process of spreading
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Open structure building design. A p
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Table bushing. A bushing used to se
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Delivering on the Nation’s promis
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