Dust Control Handbook for Industrial Minerals Mining and Processing

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type units. Some operations also contract this work to independent companies who bring inhigh-powered exhaust trucks to perform the vacuuming process. In almost all cases, a workeruses an exhaust system collector device to manually exhaust the product and dust into thecollector system (Figure 8.6). This is very time consuming and can be difficult to perform inareas that are not easily accessible in the plant. In most cases, this is not something that can beperformed on a shift-by-shift or daily basis because it is so labor-intensive. One safety issuewith these vacuuming devices is from static electricity charges that can be created whileperforming this cleaning technique. Using a nonconductive or grounded hosing material shouldeliminate the risk of this safety issue.Figure 8.6. Portable system used to perform vacuuming.In addition to hosing with water, sweeping, or using mechanical devices to clean the floors atmineral processing facilities, one last option that can be considered is to use a floor sweepcompound. Although it is not a common practice to use a floor sweep compound throughout anentire facility, some operations are using it in high traffic or extremely dusty areas to assist inminimizing the dust generated. Since there are many different manufacturers selling floor sweepcompounds, operations may want to consider evaluating some different types of material in someproblem areas to determine the effectiveness obtained within their facilities.Housekeeping should be performed at the end of each shift so that workers coming on to the nextshift start with a clean work environment. When housekeeping is performed at the beginning ofa shift, it increases the potential for worker clothing to become contaminated, which will increasethe worker's personal dust exposure throughout the work shift.One final aspect of effective housekeeping is proper upkeep and maintenance of plant equipmentand processes. When product is observed building up on floors, it indicates that some functionor process is causing the leakage. In some cases, visible dust can be seen leaking from holes ordamaged equipment, and this must be quickly corrected to minimize dust leakage. In addition,Controls for Secondary Sources 209
epetitive dust leaks should not simply be, "patched," but rather, the underlying cause should bedetermined and corrective action taken to both fix the leak and prevent future reoccurrences.Each process or function within mineral processing operations should have a Standard OperatingProcedure (SOP) that includes routine inspections, maintenance, and cleaning schedules. Whenequipment is cleaned and maintained on a routine basis, it can have a significant impact onminimizing dust liberation and generation.TOTAL STRUCTURE VENTILATION DESIGNThe first strategy to lower dust exposures in any structure is to have an effective primary dustcontrol plan that captures major dust sources at their point of origin, before they are allowed toescape out into the plant and contaminate workers. Most mineral processing plants control thedust by using standard engineering controls such as local exhaust ventilation systems, waterspray applications, scrubbers, and electrostatic precipitators (refer to Chapter 1—Fundamentalsof Dust Collection Systems). These engineering controls are effective at reducing and capturingthe dust generated and liberated from the primary sources at mineral processing plants; however,they do not address the continual buildup of dust from background sources, such as thefollowing:product residue on walls, beams, and other equipment which becomes airborne fromplant vibration or high-wind events;product that accumulates on walkways, steps, and access areas, and which may bereleased as workers move through the plant and by plant vibration;leakage or falling material from chutes, beltways, and dust collectors;lids and covers of screens that are damaged or when they are removed for inspection andcleaning; andproduct released because of imperfect housekeeping practices.Since most mineral processing structures can be considered closed systems, the background dustsources stated above, along with numerous other unnamed sources, can cause dust concentrationsto continually increase as the day or shift progresses inside these closed buildings. In order tokeep dust levels at safe and acceptable levels, a method needs to be used to control thesebackground dust sources. The most effective way to achieve this is to use a total structureventilation system.PRINCIPLES OF TOTAL STRUCTURE VENTILATIONThe basic principle behind the total structure ventilation design is to use clean outside air tosweep up through a building to clear and remove the dust-laden air. This upward airflow isachieved by placing exhaust fans at or near the top of the structure and away from plantpersonnel working both inside and outside the structure. The size and number of exhaust fans isdetermined based upon the initial respirable dust concentration and the total volume of thestructure. It must be noted that all the processing equipment within a mill generates heat and thisproduces a thermodynamic "chimney effect" that works in conjunction with the total structure210 Controls for Secondary Sources
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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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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 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: Spills of product material are a co
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 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
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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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