Dust Control Handbook for Industrial Minerals Mining and Processing

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In Figure 9.2, the parameter values are as follows:PF = protection factor, C o /C i ;C o = outside cab concentration;C i = inside cab concentration;η I = intake filter efficiency, fractional;Q I = intake air quantity;Q L = leakage air quantity;l = intake air leakage, Q L /Q I ;η R = recirculation filter efficiency, fractional;Q R = recirculation air quantity;Q W = wind quantity infiltration; andV C = cab volume.The results of this laboratory study indicate that intake filter efficiency and the use of arecirculation filter had the greatest impact on improving the air quality. When considering theuse of an intake air filter, the addition of the recirculation component significantly improved theair quality due to the repeated filtration of the cab's interior air. The addition of an intake pressurizer fan to the filtration system increased both intake airflow and cab pressuresignificantly. The cab air quality was also affected by intake filter loading and air leakage.Mathematical Model to Determine Enclosure Protection FactorIn the course of the laboratory study, the significance of the filtration system parameters was6evaluated and the following mathematical model was developed. Equation 9.2 was formulatedfrom a basic time-dependent mass balance model of airborne substances within a control volumewith steady state conditions. The equation determines the PF in terms of intake air filterefficiency, intake air quantity, intake air leakage, recirculation filter efficiency, recirculationfilter quantity, and outside wind quantity infiltration into the cab.CQQPF oI R RCiQI(1IlI) Q(9.2)WEquation 9.2 allows for a comparison of how changes in the various parameters and componentsin the system impact the PF. The wind quantity infiltration (Q w ) can be assumed to be zero if thecab pressure exceeds the wind velocity (Figure 9.3). By using Equation 9.2, operations have theability to determine the desired parameters necessary to systematically achieve a desired PF in anoperator's booth, control room, or enclosed cab to improve the air quality to safe levels and toultimately protect their workers.6This equation is dimensionless; therefore, air quantities used must be in equivalent units. Also, filter efficienciesand intake air leakage must be fractional values (not percentage values).Operator Booths, Control Rooms, and Enclosed Cabs 229
RECOMMENDATIONS FOR FILTRATION/PRESSURIZATION SYSTEMSBased on the knowledge gained from both laboratory and numerous field studies, the practicesrecommended in this section need to be incorporated in order to achieve an effective filtrationand pressurization system.Ensuring Enclosure Integrity by Achieving Positive Pressurization against WindPenetrationEnclosure integrity is necessary in order to achieve pressurization, which is critical for aneffective system. Testing has shown that the installation of new door gaskets and plugging andsealing cracks and holes in the shell of the enclosure have a major impact on increasing theenclosure pressurization. To prevent dust-laden air from infiltrating into the enclosure, theenclosure's static pressure must be higher than the wind's velocity pressure [Heitbrink et al.2000]. Equation 9.3 is used to determine the wind velocity equivalent for an enclosure (the windvelocity at which the cab is protected from outside infiltration as determined by the staticpressure):Wind velocity equivalent( 4000 pcab) fpm x 0.011364 mph/fpm(9.3)where Δр = cab static pressure in inches wg.@ standard air temperature and pressureFigure 9.3 provides a graphical display of this wind velocity equivalent. This shows that anenclosure pressure of 0.05, 0.1, 0.25, 0.5, and 1.0 inches wg would be able to withstand windvelocities of 10.2, 14.4, 22.7, 32.1, and 45.5 mph from penetrating dust into the enclosure.Although minimum pressurization has been shown to have positive results from field studies, agood rule of thumb is to have at least 0.05 inches wg of positive pressure in enclosures. Areasonable range of enclosure pressure is between 0.05 to 0.25 inches wg.230 Operator Booths, Control Rooms, and Enclosed Cabs
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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
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Figure 3.15. Air ring seal used to
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Figure 3.17. Illustrations showing
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unsubstantiated due to the inconsis
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safety considerations may preclude
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Figure 3.22. A filtration unit, loc
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Miller S, Emerick JC, Vogely WA [19
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USBM [1995]. The reduction of airbo
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110 Drilling and BlastingDUST CONTR
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Wet Control MethodsPREVENTION AND S
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Figure 4.2. Examples of compressive
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Figure 4.5. Illustration of a dry (
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Figure 4.6. Illustration of a dry (
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Wet dust control methods for crushi
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Work Practices to Minimize Dust Exp
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Some specialty grinding operations
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should be frequently inspected for
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Open screen decks slowly to allow i
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CHAPTER 5: CONVEYING AND TRANSPORTT
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Figure 5.3. Basic depiction of mate
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that the material falls before land
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Figure 5.10. Skirtboard used within
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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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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 216 and 217: DUST CONTROL HANDBOOK FOR INDUSTRIA
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
Page 224 and 225: a seal at the entry and exit points
Page 226: REFERENCESBiere G, Swinderman RT, M
Page 229 and 230: 200 Bulk LoadingDUST CONTROL HANDBO
Page 231 and 232: many years, as well as some new and
Page 233 and 234: Figure 8.2. Air spray manifold desi
Page 235 and 236: Figure 8.3. Test subject wearing po
Page 237 and 238: Spills of product material are a co
Page 239 and 240: epetitive dust leaks should not sim
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Page 243 and 244: Figure 8.8. Open-structure design c
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Page 247 and 248: Figure 8.12. Increase in worker’s
Page 249 and 250: In other cases, an operation may wa
Page 251 and 252: Cecala AB, O'Brien AD, Pollock DE,
Page 253 and 254: 224 Controls for Secondary SourcesD
Page 255 and 256: where C o = outside respirable dust
Page 257: minimal improvement in the cab's ai
Page 261 and 262: Effective FiltrationFigure 9.4. Res
Page 263 and 264: average decay times were between 16
Page 265 and 266: Figure 9.6. Filtration unit showing
Page 267 and 268: This table highlights a number of c
Page 269 and 270: NIOSH [2001b]. Technology news 486:
Page 273 and 274: upon the wind velocity (or disturba
Page 275 and 276: Maximum size is the largest particl
Page 277 and 278: Figure 10.4. Use of end-dumping wit
Page 279 and 280: conditions. Performance of each of
Page 281 and 282: A water truck, used to apply water
Page 283 and 284: Surfactants work by reducing the su
Page 285 and 286: which differed for the various site
Page 287 and 288: Figure 10.9. Self-tarping dump truc
Page 289 and 290: percent [Fryrear and Skidmore 1985]
Page 291 and 292: Figure 10.12. The armoring process
Page 293 and 294: A current method of stockpile forma
Page 295 and 296: Figure 10.15. Demonstration of how
Page 297 and 298: Chekan GJ, Cecala AB, Colinet JF [2
Page 299 and 300: Midwest Research Institute [1981].
Page 304 and 305: GLOSSARYAbrader. An implement used
Page 306 and 307: 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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