3/4/2015
Best Practices
for Belt Conveyor
Dust Control
Greg Bierie
Martin Engineering
[email protected]
Copyright Martin Engineering 2015
1
3/4/2015
Best Practices for Dust Control
1. Dust and the
Regulations
2. Open Area
Dust Control
3. Dust and
Conveyors
-3-
Fugitive Dust
Created by

Mining

Crushing

Material Handling
Less than 500 microns in size
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What’s the big deal about dust
Airborne dust is created
when dry material is
moved, manipulated,
or subjected to air currents.
• Dust is a health risk.
• Dust attracts
unwanted attention.
• Neighbors
• NGO’s
• Regulators
-5-
What’s the big deal
about a little bit of dust
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Problems from dust
Fugitive dust leads to problems:
•
•
•
•
•
•
•
Production Inefficiencies.
Extra Maintenance, Extended Outages.
Additional Housekeeping Costs.
Fire and Explosions.
Additional Safety Hazards and Accidents.
Regulatory Issues, Citations, and Fines.
Health concerns
-7-
Health Risks from Dust
Heart and Respiratory Disease
•
•
Asthma
Emphysema
Long-Term Health Issues
•
•
Healthy Lung
Lung Cancer
Silicosis
Lung Damage
-8-
Lung Cancer
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Silicosis
Cause
• Breathing crystalline silica particles
• Basic component of sand and granite
Signs and Symptoms
• Dyspnea (shortness of breath)
• Persistent Cough
• Fatigue
• Tachypnea (rapid breathing)
• Loss of appetite and weight loss
• Chest Pain
• Fever
Reducing Exposure
• PPEs
• Dust management technologies
-9-
OSHA Update
Proposal to halve and harmonize
silica exposure thresholds . . .
Reduction of permissible exposure limits
(PEL) for quartz:
 from 100 µg/m3 (general industry)
 and 250 µg/m3 (construction)
 to a uniform 50 µg/m3.
As measured in micrograms per cubic meter of air
(µg/m3) in an 8-hour weighted average
Notice of Proposed Rulemaking
published by OSHA August 23, 2013.
Regulation of exposure to silica dust
included in OSHA’s list of
“2015 Regulatory Priorities”
as published November-1021, 2014
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3/4/2015
OSHA or MSHA?
“MSHA will utilize
information provided
by OSHA to undertake
regulatory action related to
silica exposure in mines.”
“Statement of Regulatory
Priorities”…
OSHA Agency Rule List,
November 21, 2014
-11-
The Risks
of Cleaning
Around
Conveyors
•
Cleaning is NOT seen as
maintenance; it is seen as a
routine chore — drudgery
assigned to the “new kid.”
•
Often done while the
conveyor is running,
putting workers in close
proximity with moving
parts….
More than 60% of
Conveyor Accidents
come from Cleaning
Around a Moving Belt
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Conveyor workers at risk
-13-
Doing this on a moving conveyor…
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Can turn into this…
Accident Drawing from USA MSHA
-15-
Fugitive Material:
Safety Hazard
or Opportunity
• Cleaning Around the Belt Increases
Chance of Accidents/Injuries
• Fugitive Material Makes
Walkways Unsafe.
• Cleanup is a CONTINUING
Cash Drain
• Conveyor Systems can be
IMPROVED to eliminate
these problems...
Find ways to fix the problem
and eliminate the fugitive material.
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Conveyor dust control
Design to
• Maximize Throughput
• Reduce Downtime.
• Improve
Serviceability
• Eliminate
Risk
Manage
• Training
• Policies and
Procedures
• Regulatory
Compliance
Component Selection
• Best Available Technology
• Green Zone Transfer
• Dust Containment
• Dust Suppression
• Dust Collection
• Belt Cleaning
• Belt Tracking
• Belt Support
• Flow Aids
Manage
• Exposure
to Dust
• Guarding
• Confined Space
• Hot Work
Safety & Environment
-17-
Pyramid Approach
to Dust Control
Suppression
Collection
Containment
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Collection of dust
Dust Collectors
(Baghouses)
• Ventilation principles.
• Collects and isolates dust.
• Advantages vs
disadvantages.
-19-
Suppression of dust
Adding moisture
to limit escape
of airborne particles
•
Added moisture
can impair process
•
Technologies:
 Fire Hose
 Sprinklers
 Engineered Systems
•
Advantages vs
disadvantages
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Containment of dust
Enclosing the equipment and
the material that release the dust
Keep material
and process
enclosed,
so dust
cannot escape.
Note
• Dome for
stockpile
• Enclosed
galleries
and transfer
houses on
belt conveyors
-21-
When you can’t confine it…
Traditional open area dust control
Wind Fence
Surface Wetting (Fire Hose)
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3/4/2015
Technology for open area control
Atomized misting
Uses water in fine mist
to capture solid particles
of similar size.
• Avoids oversaturation
• Reduces GPM vs surface
wetting
• Reduces labor hours
-23-
Open area dust suppression
Click in Picture to Show Video Clip
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3/4/2015
Atomized Misting
•
Creates mist of particles
from 50-200 Microns
•
Higher effectiveness
•
Larger coverage area
Slipstream Effect
-25-
Coverage of large open areas
Unit
Coverage Area
DB-30
31,000 ft2
DB-45
74,000 ft2
DB-60
125,000 ft2
DB-10
280,000 ft2
57,600 ft2
Football
Field
-26-
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3/4/2015
At conveyor discharge
Dust Suppression Ring
•
Produces virtual curtain of mist
to control dust at conveyor discharge
-27-
Suppression at truck dumps
Control dust at truck
dump with automated
suppression system.
• Spray directed into
crusher to catch
rising dust.
• Controls automatically
activate system
during unloading.
Click in Picture to Show Video Clip
Automated systems
effective in other locations
-28-
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3/4/2015
At crushers & conveyors
Dust suppression controls dust at source
Using appropriate nozzles,
with correct water pressure,
moisture is added to the air
above conveyor transfers
and crushers to mate with
airborne dust, returning
particles to the ground
or back into the process.
-29-
Conveyors generate dust
Airborne dust
is created
when dry material
is moved, manipulated,
or subjected
to air currents
Dust becomes
airborne during
conveyor…
 loading
 unloading
 movement of cargo
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3/4/2015
Belt cleaning as dust control
•
•
Cleaners remove carryback
to reduce fugitive material.
Cleaners require
maintenance;
look for methods
to make cleaner service
simple and safe.
Click to Show Video Clip
-31-
Mainframe slides out
for simple and safe blade replacement
Mainframe
never comes
off its mount
SHOWN HERE
Martin DT2
Inline
Secondary
Cleaner
in Australia
Click to Show
Video Clip
(2 Minutes)
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3/4/2015
Adding off-pulley cleaners
Extra cleaners to improve cleaning performance
Installed under
the main conveyor,
a scavenger conveyor
captures material
cleaned from belt
and moves it
to discharge chute,
allowing cleaners
to be installed
along belt return.
Click to Show Video Clip
Eliminates the need
for personnel to crawl
under conveyor to clean.
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For a really clean belt
•
Modular belt washing station
cleans belt with minimal water.
•
Pre-engineered sections
create custom washbox
to match needs of application.
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3/4/2015
Air movement lets dust escape
To reduce escape of fugitive dust, manage air movement.
Types of
Air Movement
 Displaced air
 Induced air
 Generated air
-35-
Getting a handle on dust
Control material flow at loading
• Control load placement
• Minimize air entrainment
Use modular loading zone
components
• Support the belt to prevent
spillage and dust.
• Contain dust
in covered enclosure.
• Seal enclosure to prevent
escape of fugitive material.
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Modular loading zone
-37-
Improving transfer points
for easier, safer service
Engineered for Serviceability
Modular Components
•
To match requirement
•
To allow future upgrade
Center the material load
•
To control tracking
•
To reduce fugitive material
(dust and spillage)
•
To minimize dust
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Loading zone enclosure
-39-
Control load placement
Centralize cargo, reduce impact,
control the amount of air driven off
Reducing
 Impact damage
 Belt abrasion
 Mistracking
 Air entrainment
 Dust generation
Angled loading plate lays cargo
on receiving belt in direction of belt travel
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3/4/2015
Control load placement
Centralize cargo,
reduce impact,
control the amount
of air driven off
to minimize
escape of dust
Lining or
Loading Plate
lays cargo
on receiving belt
in direction
of belt travel
Reducing
 Impact damage
 Belt abrasion
 Mistracking
 Air entrainment
 Dust generation
-41-
Problems with linings
Chute liners/deflectors are
• Prone to abrasive wear.
• Impossible to adjust without
trial-and-error downtime.
• Not serviceable.
• Hard to replace.
• Custom made.
• Expensive.
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3/4/2015
Adjustable loading plate
• Centers cargo.
• Allows simple
adjustment or
replacement
to compensate
for wear.
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Improved belt support
Keeps belt stable, like running over a table
• Stabilizes belt path.
• Decreases dust
and spillage.
• Reduces maintenance
requirements.
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3/4/2015
Close idler spacing
• Close idler
spacing
stabilizes
the belt.
• But creates
service
problems.
-45-
Service-friendly idlers
Track-mounted rollers allow slide-out service
from either side of structure.
Click to Show Video Clip
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3/4/2015
Cradles to support belt
Stabilize belt path to control fugitive material
• Improves edge sealing
to control spillage.
• Minimizes fluctuation
in belt path
that allows dust to escape.
•
Impact Cradles
•
Slider Cradles
•
Combination Cradles
-47-
Slide-in/slide-out for service
No entry of confined spaces
Track-mounted components
allow maintenance
from outside the conveyor structure.
Click in Picture to
Show Video Clip
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3/4/2015
Modular skirtboard design
Improves control of air and dust
• Longer skirtboard
gives cargo time to settle.
• Higher walls allow air to
slow so dust drops out.
• Top cover prevents dust
escape.
• Prefabricated components
allows engineering of stilling
zone.
• Bolted flanges allow
simple assembly and
alterations to match
operating requirements.
-49-
Wear liner protects seals
• Improve sealing
effectiveness and life
by keeping pressure
of material load away
from sealing strip.
• But traditional wear liner
(inside of the skirtboard)
is hard to install,
worse to replace,
difficult to inspect,
and impossible
to adjust.
-50-
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3/4/2015
External wear liner
Liner located OUTSIDE
the skirtboard
• Preserves sealing strip
by keeping weight of cargo
off the elastomer seal.
• Easier to install, inspect,
adjust, and replace,
from outside the enclosure.
-51-
Wear liner adjusts from outside
External
wear liner
allows
adjustment
or
replacement
from outside
the structure.
Click in Picture
to Show Video Clip
Mounting system allows wear liner to be moved down toward belt
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3/4/2015
Low maintenance skirt seal
Outrigger flap maintains
effective containment
of dust and fines.
Seal rides on belt;
self-adjusting
to accommodate
fluctuations in belt travel.
Improved adjustability,
when service required.
-53-
Effective seal prevents spillage
Multiple-barrier
sealing system
keeps
fine material
on belt
while allowing
simple
adjustment
and
replacement.
Click in Picture
to Show Video Clip
Sealing strip flips for double wear life
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3/4/2015
Controlling air movement
Passive Controls
• Reduce airflow with baffles
and curtains.
• Trap dust with dust bags.
Active Technologies
 Remove dust from air stream
with dust collectors.
 Minimize escape of dust
with suppression systems.
-55-
Passive controls for dust
Control air movement to minimize dust escape
•
Skirtboard Covers
contain the air stream,
allowing it to slow.
•
Air Baffles
prevent air from
entering transfer point.
• Dust Curtains
slow air leaving
transfer point.
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3/4/2015
Dust bags for passive control
Bags provide dust collection
without consuming energy.
When loading stops,
airflow stops,
and bag collapses,
dropping collected dust
back onto belt.
-57-
Insertable air cleaner
Air cleaner
above load zone
collects airborne dust
before it escapes.
•
Self-cleaning system
returns dust to conveyor.
•
Small footprint.
•
Low energy consumption.
Click in Picture
to Show Video Clip
-58-
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Wet suppression systems
Water, or enhanced water, applied as spray, foam, or fog
•
Systems designed
to match materials
and conditions.
•
Chemicals can be added
to minimize water use
while providing
longer-term effect.
-59-
Modular settling zone
with Dust Management Options
Click to Add
Insertable
Air Cleaner
Click to Add
Fog System
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3/4/2015
Best practices for dust control
Dynamic transfer point design with modular components
 Replaceable loading plate
to centralize cargo,
control impact, and
reduce air expulsion.
 Baffles and dust curtains.
 Effective seals at belt edge.
 Passive dust collectors
(bags).
 Insertable air cleaners to control
dust as it is created.
 Dust suppression where water is available and
material allows.
-61-
And one more thing: training
•
Conveyors and their hazards
– Danger Areas
– How Conveyor Accidents
Happen
•
How To Work Safely
Around Conveyors
(Best Practices)
•
How To Make Conveyors
Run Better
How to Make Conveyors Run Better
(Cleaner and More Productively)
and so Reduce the Activities
that Lead to Accidents
(Maintenance and Cleanup).
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3/4/2015
Conveyor Training
Classroom Workshops
•
•
Available at your facility
or neutral site
3 Levels now available
• Basic
• Operations and
Maintenance
• Advanced
Classroom Training:
can be customized
for specific plant
equipment and problems.
-63-
Who has the first question?
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3/4/2015
Reduce dust problems
Issues with dust
and housekeeping
are here for the long haul,
with increasing regulation
and environmental
pressures
Head off problems
using effective
technologies
for conveyor
dust control
-65-
“If you do
what you’ve always
done,
you’ll get
what you’ve always
gotten.”
Anthony Robbins,
Leadership Consultant
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3/4/2015
Best Practices
for Belt Conveyor
Dust Control
Greg Bierie
Martin Engineering
[email protected]
Copyright Martin Engineering 2015
THE END
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