Dust Control Handbook for Industrial Minerals Mining and Processing

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overlap to eliminate any gaps that may occur in the air-blocking shelf perimeter. Thesemodifications should not diminish the effectiveness of the air-blocking shelf.Collector Dump DischargeThe collector dump cycle can account for as much as 40 percent of the respirable dust emissions[USBM 1985]. The dust collector dump cycle operates in one of two modes: trickle mode orbatch mode. In the first mode (trickle mode), the collector filter cleaning mechanism operates atpreset time intervals, e.g., every 1 minute. This allows the fine material from the collector totrickle out onto the ground. In the second mode (batch mode), the collector cleaning mechanismoperates when the bailing airflow stops. This condition occurs during intervals when adding orremoving drill steels, or when removing the drill bit from the hole. The batch mode creates thehighest dust levels because of the longer accumulation time of fine material in the collectorbefore dumping. During the batch mode, the dust is usually emitted into the ambient air whenthe fine material is dropped, which creates significant dispersion. Also, this fine material strikesthe ground, producing more dust dispersion. Finally, the drill itself and service vehiclesfrequently drive through the dust pile formed by dumping, stirring up clouds of dust. Avoidingdisturbing the collector dump piles will prevent dust from being entrained into the air.Preventing Collector Dump Dust EntrainmentThe dust collector dump point is generally anywhere from 24 to 36 inches above the drill bench.Dumping the fine material from this height causes entrainment of the respirable sized fraction ofthis material into the air. To reduce this entrainment and lower the respirable dust concentrationsat the collector dump point, a piece of brattice cloth can be attached to the dust collector dumpusing a large hose clamp. Figures 3.13 A, B, and C show the installation of the dust collectordust shroud. This dust shroud was installed over the existing rubber boot attached to the dustcollector dump.Figure 3.13. Dust collector dump point prior to shroud installation (A).Two men installing the shroud onto the dust collector dump point (B).The dust collector dump point after installation of the shroud (C).Drilling and Blasting 93
This simple procedure of creating a dust collector dump shroud has been shown to be veryeffective in reducing the respirable dust. Respirable dust concentrations measured after3installation of the dust collector shroud ranged from 0.16 to 0.24 mg/m . Figure 3.14 shows thereduction of the respirable dust concentrations near the collector dump point with and withoutthe dust collector shroud. It can be seen that the respirable dust generated by the dust collectordump point can be reduced by between 63 and 88 percent using the shroud [Reed et al. 2004]. Itshould be noted that this reduction is highly dependent upon wind direction and wind speed.Advantages to this method of respirable dust reduction are that the material is inexpensive andrequires almost no maintenance. If the shroud becomes damaged, it can easily be replaced in10–15 minutes requiring little, if any, downtime for the drill.Figure 3.14. Comparison of dust concentrations of uncontrolled dustcollector dump to shrouded dust collector dump.To install the shroud, the length of brattice cloth (or similar material) should be sufficient toallow it to extend from the dust collector dump point to the ground. It should be cut so that it isonly long enough to just touch the ground when the drill is lowered. When wrapping the clotharound the dust collector dump, the overlap should be placed so that it is on the outside of thedust collector dump (i.e., it should be visible as the installer looks directly at the dust collectordump, as shown in Figure 3.13 C). This overlap allows the cloth to expand as fine material isdumped to the ground, while containing the entrained respirable fraction within its confines.Placement of the overlap on the outside also keeps the fine material off the drill tracks, whichotherwise could cause re-entrainment of the respirable size fraction of the material when the drillstarts in motion.94 Drilling and Blasting
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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
Page 72 and 73: Electrostatic precipitators normall
Page 74 and 75: may be related to specific applicat
Page 76 and 77: times. When considering the depth o
Page 78 and 79: Figure 1.25. Demonstration of how a
Page 80 and 81: Figure 1.26. A typical fan performa
Page 82 and 83: Fan TypesThere are two basic types
Page 84 and 85: Figure 1.30. Typical centrifugal fa
Page 86 and 87: Figure 1.32. Typical roof ventilato
Page 89 and 90: DUST CONTROL HANDBOOK FOR INDUSTRIA
Page 91 and 92: The vast majority of dust particles
Page 93 and 94: Table 2.1. Particle/droplet size in
Page 95 and 96: Air Atomizing NozzlesAir atomizing
Page 97 and 98: Hydraulic Flat Fan NozzlesFigure 2.
Page 99 and 100: for dust knockdown or suppression,
Page 101 and 102: Nozzle MaintenanceFigure 2.14. Typi
Page 103 and 104: Accidental DamageInadvertent harm t
Page 105 and 106: NDT Educational Resource Center, Io
Page 107 and 108: 78 Wet Spray SystemsDUST CONTROL HA
Page 109 and 110: contains a piston which delivers ha
Page 111 and 112: produce an increase in the penetrat
Page 113 and 114: Dry DrillingDry drilling is accompl
Page 115 and 116: Circular ShroudIn contrast to the u
Page 117 and 118: The collector airflow has a more su
Page 119 and 120: Air-Blocking ShelfThe air-blocking
Page 121: dust emissions from mast lowering,
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
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CONVEYOR DESIGN AND MAINTENANCE ISS
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Figure 5.15. Conveyor transfer encl
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High-volume, high-pressure sprays s
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Figure 5.19. Depiction of a bucket
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Figure 5.21. Depiction of two types
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Figure 5.25. Venturi eductor utiliz
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CHAPTER 6: BAGGINGThis chapter disc
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caused during manufacturing, includ
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Overall PerforationsThe use of over
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Figure 6.5. Open-top bag being load
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Bagging operators should be aware t
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Figure 6.8. Exhaust hood to capture
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In the original design, a single no
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The OASIS is a relatively simple de
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Figure 6.13. Bag storage shelves sh
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Figure 6.14. Bag and belt cleaner d
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other industrial application using
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The robotic arm automatic palletize
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For many years, this plastic wrappi
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warehouse location until a later ti
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used successfully to perform this c
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CHAPTER 7: BULK LOADINGDuring the b
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Figure 7.2. Loading spout discharge
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Cascading Loading SpoutFigure 7.5 i
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a seal at the entry and exit points
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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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