Dust Control Handbook for Industrial Minerals Mining and Processing

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Checklist for Hood EffectivenessThe following is a checklist of effective practices or considerations regarding the use of hoods inexhaust ventilation systems.The most effective hood design is one that encompasses the entire dust generationprocess. This virtually eliminates dust escaping and contaminating mine/plant air and theexposure of workers.Openings/doors/access points into the hood should be minimized as much as isreasonably possible. When access is necessary, a partial enclosure application, normallyreferred to as a booth or tunnel, is then recommended. When access points are not able tobe closed, sealing these areas with clear plastic stripping is a common and effectivetechnique.When neither total nor partial hood enclosures are possible, capture hoods should beused. The hoods need to be located as close to the dust source as feasibly possible.Remember that the distance component is a squared relationship that affects the requiredhood air volume.Hood capture velocities must be able to overcome any exterior air current between thedust source and the hood.The use of a push-pull ventilation system should be considered when the distancebetween the dust source and the hood becomes too great, or when there are significantexterior air currents in the area.It is critical that makeup air drawn past a worker before entering an exhaust hood beessentially dust-free. If the air is drawn from a contaminated area, the potential exists toincrease a worker's respirable dust exposure. Dust-laden air from a dust source shouldnever be pulled through a worker's breathing zone as it is being drawn into an exhausthood.Flanges on hoods should be used because they significantly improve the airflow from thefront of the hood area, which should be directed towards the dust source. In cases wherebell shaped hoods and ducts can be used, they provide the optimum design.All hoods should be designed to meet the criteria established by the ACGIH handbook,Industrial Ventilation: A Manual of Recommended Practice for Design [ACGIH 2010].DUCTWORK AND AIR VELOCITIESThere are three basic types of systems used to transport dust to the collector: high-velocity, lowvelocity,and modified low-velocity. Most familiar to industry is the high-velocity system,where air-carrying velocities are in the range of 3,000–4,500 fpm. Fundamentally, this is a dustcollection system, while a low-velocity system can best be described as a dust containmentsystem, with duct velocities always less than 1,800 fpm. Low-velocity systems are designed sothat they will not transport nonrespirable size dust particles (generally particles over 10 μm). Itis important to keep in mind that low-velocity transport does not imply low airflow. Capturevelocities (the air velocity at the hood opening required to capture the contaminant) and hood airvolumes are the same in all designs, be they high-velocity, low-velocity, or modified lowvelocitysystems. Figure 1.9 depicts the basic difference between high- and low-velocitysystems.Fundamentals of Dust Collection Systems 19
The implication of the figure is that, in a high-velocity system, the dust will be carried to thecollector regardless of the slope or angle of the duct. However, in a low-velocity system, it isnecessary to slope the duct to an inlet hood or discharge point, because some of the largerparticles, inadvertently collected, will settle out in transport, and must be removed.High-Velocity SystemsFigure 1.9. Schematics of high- and low-velocity systems.The high-velocity system is characterized by its ability to carry dust-laden air (particles largerthan 10 μm) from the entry points of the system to the dust collector without having the particlessettle out in the duct. To keep the particles from settling, high transport velocities are required.Because the ducting in a high-velocity system can be run both horizontally and vertically, thereare few engineering restrictions. Effective ducting layouts can be easily designed, normally witha central horizontal duct and smaller collection ducts branching off to the dust-producingequipment/hood.20 Fundamentals of Dust Collection Systems
Page 2 and 3: Report of Investigations 9689Dust C
Page 4: FUNDAMENTALS OF DUSTCOLLECTION SYST
Page 7 and 8: Minimizing Field Fits and Welds ...
Page 9 and 10: Recommendations for Proper Wet Dril
Page 11 and 12: CONTROL TECHNOLOGIES FOR FILLING 50
Page 13 and 14: Effective Filtration ..............
Page 15 and 16: ILLUSTRATIONSFigure 1.1. Relationsh
Page 17 and 18: Figure 3.2. The air and water flow
Page 22: Figure 9.5. Problem created by heat
Page 25 and 26: UNIT OF MEASURE ABBREVIATIONSUSED I
Page 28: Robert J. Franta, Quotation Enginee
Page 32 and 33: silica. Quartz is the most common s
Page 34 and 35: DUST CONTROL HANDBOOK FOR INDUSTRIA
Page 36 and 37: CHAPTER 1: FUNDAMENTALS OFDUST COLL
Page 38 and 39: The shape of particles affects how
Page 40 and 41: EXHAUST SYSTEMS DESIGNAll exhaust s
Page 42 and 43: stripping, which allows workers to
Page 44 and 45: When using the air quantities in Ta
Page 46 and 47: X = distance in feet from the face
Page 50 and 51: A major disadvantage of the high-ve
Page 52 and 53: A common misconception when designi
Page 54 and 55: Avoiding Mitered Elbows Greater Tha
Page 56 and 57: Figure 1.13. Depiction of the horiz
Page 58 and 59: Figure 1.14. Typical design of grav
Page 60 and 61: Baghouse CollectorsBaghouse dust co
Page 62 and 63: Table 1.2. Emission factors for cru
Page 64 and 65: Figure 1.17. Typical design of a me
Page 66 and 67: Reverse Jet (Pulse Jet) CollectorsR
Page 68 and 69: Figure 1.20. Cartridge collector wi
Page 70 and 71: 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.
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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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DUST CONTROL HANDBOOK FOR INDUSTRIA
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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
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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
Page 312 and 313:
Table bushing. A bushing used to se
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Delivering on the Nation’s promis
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