Dust Control Handbook for Industrial Minerals Mining and Processing

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During a field study by the National Institute for Occupational Safety and Health(NIOSH), the application of water was shown to prevent high dust emissions from thehaul road for several hours after application during a hot dry day when the skies were clearof any clouds [Organiscak and Reed 2004]. The application rate of the water was notmeasured, but was observed to be very liberal as observations of the water truckapplication noted water runoff from the haul road. During the day the temperature rangedfrom a low of 77°F increasing to 90°F and the relative humidity ranged from a high of 64percent decreasing to 37 percent throughout the day. Figure 10.8 shows the dustconcentrations measured throughout the day with one water application at approximately10:00 a.m.Figure 10.8. Respirable dust concentrations measured from haul roadafter water application occurred at 10:00 a.m. [Organiscak and Reed 2004]There are no published guidelines for the amount of water to use for dust control on haulroads. In the past, an old U.S. EPA emissions factor had stated that days having as little as0.01 inches of precipitation resulted in no dust emissions from haul trucks [EPA 1998].However, it was not until recently that the optimal haul road moisture content for bestreduction of respirable dust was found to be approximately 2 percent in a study completedin Kansas [Mulesky and Cowherd 2001]. Additionally, except for the applicationintervals previously mentioned, there are no published guidelines for determiningoptimum haul road watering intervals. Determining optimum haul road watering intervalswould be dependent upon the amount of water applied to the road, the time between waterapplications, the traffic volume of the road, and the prevailing meteorological conditions[Cowherd et al. 1988].SurfactantsSurfactants or wetting agents can be added to the water to extend its life as a dust controlagent. Like water, surfactants generally do not require any special application procedures,except to remove any excess loose material from the road surface.Haul Roads, Stockpiles, and Open Areas 253
Surfactants work by reducing the surface tension of water. This allows the particles fromthe road surface to better penetrate the water droplets, thereby increasing the potentialsurface area coverage of the droplet (i.e., the penetration of the water droplet lets the waterwet a larger surface area). The reduced surface tension also permits easier penetration ofthe treated water into a few inches of the sub-surface. This action allows the wetted subgradeto act as a reservoir of water such that, once the surface moisture evaporates, thesub-grade can provide moisture for dust control through capillary action, thus extendingthe life of the water [Midwest Research Institute 1981].There is very little information about the use of surfactants to extend the effective life ofwatering haul roads. However, observations have noted that the time between wateringroads can be extended 33–50 percent when surfactants are used [Midwest ResearchInstitute 1981].SaltsSalt solutions are commonly mixed with water and used for haul road dust control.Magnesium chloride is one of the most common salt-based dust control agents. Otheragents are calcium chloride, hydrated lime, and sodium silicates, with calcium chloridebeing the most common and having properties similar to magnesium chloride. Calciumchloride is hygroscopic and deliquescent, meaning that it absorbs moisture from theatmosphere to keep the road in a moist condition. In very dry climates, periodicapplication of water may be required to maintain road performance at acceptable levels[Midwest Research Institute 1981]. Application procedures for magnesiumchloride/calcium chloride are similar to those described for dust suppressants in thesection titled "Road Preparation."After application to control haul-truck-generated dust, magnesium chloride controlefficiencies were shown to average 95 percent for up to 22 days after application [USBM1987]. For calcium chloride, two weeks after the initial application, the control efficiencywas measured as 82 percent and decreased over time to 14 percent at seven weeks afterapplication [USBM 1983]. This decline has been attributed to road surface wear due totraffic volume and precipitation, in that chlorides are water soluble and can be washedaway.Advantages of using chlorides for dust control are that they absorb moisture from theatmosphere to maintain the moisture content of the road at a higher level than normal.They can also act as a de-icer to thaw ice and snow on roads in freezing conditions. Also,chlorides generally do not require time to cure after application.Disadvantages are that chlorides may cause corrosion on equipment using the roadssooner than normal. They can also be harmful to vegetation and to personnel if skin oreye contact occurs. Chlorides are also water soluble and may leach from the road surfaceduring precipitation, thereby degrading in performance over time [Midwest ResearchInstitute 1981].254 Haul Roads, Stockpiles, and Open Areas
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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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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
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
Page 241 and 242: Effective Upward Airflow PatternThe
Page 243 and 244: Figure 8.8. Open-structure design c
Page 245 and 246: manually removing the bags and plac
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 and 258: minimal improvement in the cab's ai
Page 259 and 260: RECOMMENDATIONS FOR FILTRATION/PRES
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 271 and 272: DUST CONTROL HANDBOOK FOR INDUSTRIA
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: A water truck, used to apply water
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 302 and 303: DUST CONTROL HANDBOOK FOR INDUSTRIA
Page 304 and 305: GLOSSARYAbrader. An implement used
Page 306 and 307: Carryback. Material that sticks or
Page 308 and 309: End-dumping. A process of spreading
Page 310 and 311: Open structure building design. A p
Page 312 and 313: Table bushing. A bushing used to se
Page 314: Delivering on the Nation’s promis
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