A SUSTAINABLE APPROACH TO MANAGE DUST EMISSION
DURING HANDLING AND TRANSPORT OF COAL
AND IRON ORE
John Planner
Introspec Consulting, Epping, NSW, 2121, Australia
Abstract
There is an increasing requirement to minimise dust emission from bulk handling facilities located in close
proximity to residential areas, particularly in the context of dramatically increasing export volumes. Lower
level dust emissions can be controlled by operational measures such as water addition to products, and use
of water spray on stockpile surfaces. Recent research has shown that higher levels of dust emission can be
more effectively controlled by understanding and treating the dustiness characteristics of each individual bulk
product. Wind tunnel research has demonstrated speeds at which surface dust lift-off can occur, and the
relative performance of stockpile surface treatment using water spray or one-off veneer application. This
research is being progressively applied at Australia’s coal and iron ore port terminals and rail transport
systems. On-site deposition measurement and continuous air quality sampling, following application of the
research, has demonstrated that emission levels comply with health standards, and that dust nuisance
effects are being minimised to an acceptable level. Key words: Dust, Coal, Iron Ore, Research.
1.
Introduction
1.1 Sustainability objectives
As Australia’s coal and iron ore export levels
increase to meet international market growth, port
terminals, mining operations, and rail transport
systems are being expanded to handle increasing
volumes. In the context of dust management, coal
and iron ore industry sustainability objectives can
be summarised;
 Social: Community relations, and workplace
health and safety
 Economic: Profitability, increased coal and iron
ore export volumes which generate income of
high importance to the Australian economy
 Environmental: Impact of operations on air,
water, land, community health, and community
life quality.
Meeting these sustainability objectives generates a
demand for improved management of dust emission
from all elements in the mine to ship transport
chain. The improvement can be achieved by
addressing the unique dustiness characteristics of
each individual coal type and iron ore type.
Elevated deposition levels of particles in the fine
to coarse size range, rather than the very fine size
range, are the cause of most community nuisance
complaints. Very fine particles with an
aerodynamic diameter less than 10 micrometres
(PM10) may have the potential to adversely affect
human health.
Typical environmental protection agency air
quality guidelines require PM10 levels to be less
than 150 micrograms per cubic metre over a
twenty four hour averaging period, and less than
50 micrograms per cubic metre over a one year
averaging period.
However these threshold levels have been
determined from epidemiological studies of city
populations exposed to urban aerosols. As most
coal and iron ore port terminal and rail transport
operations are located adjacent to less densely
populated residential areas, the current air quality
standards are likely to overestimate the potential
for health impacts.
2. Mine to Ship Dust Emission Sources
2.1 Mine site dust emission
1.2 Community concerns
Responses received from communities in close
proximity to bulk handling facilities indicate that the
major dust related environmental concerns are
health effects, and the following amenity impacts:




Poor short term visibility
Dust deposition on house surfaces
Soiled washing and curtains
Dust deposition on cars, boats, etc
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Emission from iron ore mining production and a
majority of coal mining production results from
open cut mining operations. A recent NSW Coal
Mining Benchmarking study conducted for NSW
DECCW, in Katestone Environmental (2010),
stated that typical open cut coal mining operations
resulted in the following top four contributors to
total particulate emission;

Wheel generated dust – 50%



3. Coal and
Characteristics
Wind erosion (overburden) – 19%
Bulldozers – 9%
Trucks dumping overburden – 4%
Iron
Ore
Dustiness
3.1 Bulk products dustiness characteristics
2.2 Rail transport dust emission
During rail transport from mine to port the primary
sources of dust are:
 Coal surface of loaded wagons
 Coal leakage from doors of loaded wagons
 Wind erosion of spilled coal in corridor
2.3 Port terminals
The primary port terminal dust emission sources
are;
 Stockpile lift-off
 Stacking, particularly if done by fixed height
trippers and use of dozers
 Reclaiming, particularly if involving dozer
operation
 Conveyors including transfers
Research has shown that bulk products dustiness
characteristics have a major impact on the level of
dust emission during handling and transport. It has
been shown that every product type transported
through the mine to ship transport system has
unique dustiness characteristics, including;
 Dustiness/moisture relationship
 Ultra-fines content
 Rate of moisture loss by seepage
The following sections provide brief information on
the contribution of recent research, the outcomes
of which are achieving a significant reduction in
dust emission from bulk handling and transport
activities. (Planner J.H. 2004)
4. Dustiness/Moisture Relationship
2.4 Traditional
management
approach
to
emission
The traditional approach for management of dust
emission from bulk handling facilities has involved
enclosure of emission sources and addition of
water to the product. However secondary problems
can occur when water is applied to the bulk product
on a random basis.
Addition of moisture must be carefully controlled as
excessive water may reduce the economic value of
the product for its end use, and incur financial
penalties.
Excessive moisture content can also lead to
handling problems due to sticking in chutes and rail
wagons.
Traditional operational dust containment and
suppression features include stockpile water spray
systems, enclosure of conveyor transfers, conveyor
belt cleaning, minimised stacker drop height,
misting sprays on reclaimers, stackers, and
conveyor transfers, and minimised use of mobile
equipment.
4.1 Moisture content
As there is a direct relationship between dustiness
and moisture content for bulk products, such as
coal and iron ore, control of moisture level is the
most significant method of controlling air-borne
dust emission. Most bulk products lose surface
moisture by evaporation, seepage, and hot dry,
windy conditions.
4.2 Dustiness/moisture test procedure
The relationship between dustiness and moisture
content, and the dust extinction moisture level
(DEM), can be determined by a procedure
documented in Australian Standard AS 4156.62000 Coal Preparation Part 6: Determination of
dust/moisture relationship for coal. Apparatus in
the laboratories of Tunra Bulk Solids Research
Associates, Newcastle NSW (TUNRA) is shown in
Figure 1.
Due to extensive throughput expansion of port
terminals operating in close proximity to residential
areas, more effective procedures to control dust
emission have been required.
To meet this requirement, research has been
conducted into the unique dustiness characteristics
of individual iron ore and coal products to minimise
dust emission from handling and transport
operations. (Planner J.H. and Jackson P. 2001)
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Figure1. Test apparatus used to determine the
relationship between dustiness and moisture
content for coal and iron ore
Dust Number
1000
1000
120
Optimum
Moisture
range
100
100
80
60
10
40
20
100
0
1
0
DEM = 7.4%
2
4
6
8
10
12
%H O
Moisture
2 (%)
10
Figure3. Dust/moisture relationship and flow
property/moisture relationship indicate
optimum moisture range for typical iron ore
1
0
2
4
6
8
10
Moisture Content (%)
Figure 2. Relationship between dustiness and
moisture content for typical coal or iron ore
sample showing dust extinction moisture level
(DEM)
If the moisture level for products handled
through the mine to ship transport chain is
maintained above DEM level, dust emission
will be minimised during all handling
operations. The procedure has been
successfully applied in operations at the
Dalrymple Bay and Hay Point Coal Terminals
in Central Queensland.
4.4 Management of moisture content and
handling problems
The necessary moisture level to achieve dust
management can be achieved, while also
ensuring that bulk flow problems, described in
section 2.4, do not occur due to excess
moisture content, by determination of the flow
problem moisture target (FPM).
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5. Reduction in Ultra-fines content
by Chemical Agglomeration
5.1 “Very dusty” bulk products
Some iron ore and coal types create severe
levels of dust emission. Products may be free
draining, causing a rapid drop in moisture
content. Other very dusty products may be
run-of-mine and contain non-coal particles.
As it is difficult to continually replenish lost
moisture, an alternative is to apply a chemical
additive to the mass of coal to achieve
agglomeration of ultra-fine particles, to
minimize dust emission by creating a higher
proportion of larger particles which resist
becoming airborne.
5.2 Ultra-fines reduction by chemical
agglomeration
Total agglomeration treatment involves
application of a selected chemical diluted in
water and applied to selected “very dusty”
products. This procedure was employed on all
coal types shipped through NSW coal
terminals at Carrington, Kooragang Island and
14
Time (s)
As tests are conducted on a coal sample size of
1.2 kilograms, or 2.2 kilograms iron ore, the test
material is limited to a maximum particle size of
6.3mm. A procedure has been developed to adjust
the DEM level for the product full size range.
Dust Extinction Moisture Graph
Flow
Problem
Dust Problem
Durham Cone Flow Time (s)
A logarithmic line of best fit to plot the relationship
between dustiness and moisture content for a
typical coal or iron ore type is shown in Figure 2.
The dust extinction moisture level (DEM) is
determined as the moisture level at which the plot
line intersects a dustiness level (dust number) of
10.
Dust Number (Dust Yield x 10,000)
4.3 Dust extinction moisture level
A combined graph of DEM and FPM for a
typical iron ore product is shown in Figure 5.
This illustrates the optimum moisture range,
within which dust emission problems and
handling flow problems can both be
minimized.
Dust Number
The procedure has been effectively adapted for
iron ore and other bulk solids products. (Djukic M
and Planner JH, 2008)
Port Kembla in the late 1970s to the late
1980s, until other dust management methods
were implemented.
below DEM, dust lift-off occurs at an
increasing rate with rising surface wind speed.
The traditional practice to replace moisture
lost from stockpile surfaces involves
Laboratory tests have recently been
conducted to re-apply the procedure on
selected coal and iron ore types. More
effective laboratory procedures are now
available to develop chemicals which can
agglomerate ultra-fines to achieve a low value
of dustiness even at low moisture levels.
1000
Untreated
Treatment
Dust Number
100
5.3 Fines reduction test procedure
The test work involves the application of
agglomerating chemical to measure the
reduction
in
dustiness
using
the
dustiness/moisture
test
apparatus
in
accordance with Australian Standard AS
4156.6-2000. The results achieved following
agglomeration are compared with results of
un-treated samples.
10
1
0
0.5
1
1.5
2
2.5
3
3.5
Moisture Content (%)
Typical test results for coal and iron ore are
shown in Figures 4 and 5. The full line shows
dustiness/moisture relationship for un-treated
sample. The dotted line shows the relationship
for the treated sample. The treated samples
achieve DEM at lower moisture content.
Figure 5 Relationship between dustiness
and moisture content for typical iron ore
sample following total agglomeration treatment
compared with untreated sample
1000
application of water by stockyard spray
system or mobile spray tanker. A high level of
success is achieved under most climatic
conditions, but involves use of large volumes
of water, sometimes where water usage is a
major concern. A combination of high
temperature and high wind speed may still
lead to unacceptable levels of surface dust liftoff, with water application.
Treated
Untreated
Dust Number
100
10
1
0
6.2 Dust lift off wind speed
2
4
6
8
10
12
Moisture Content (%)
Figure 4 Relationship between dustiness and
moisture content for typical coal sample
following total agglomeration treatment
compared with untreated sample
6. Stockpile Surface Dust Emission
6.1 Surface moisture loss
Moisture is lost by evaporation from the
surface of iron ore and coal stockpiles at a
rapid rate, compared with the main mass of
stockpiled product, due to exposure to sun
and wind. As the surface moisture level falls
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In assessing the most appropriate stockpile
surface treatment for individual bulk materials
product types, it is helpful to understand the
wind speeds at which dust lift-off occurs.
Simulated stockpile conditions can be
established in a wind tunnel.
A laboratory test procedure has been
developed by Introspec Consulting, using a
wind tunnel in the TUNRA laboratories. The
apparatus is shown in Figure 5. Test trays are
placed in the wind tunnel at an angle
simulating typical angle of repose.
Samples are exposed to a gradual increase in
wind speed and visual observations are made
to record wind speed at which;
 Saltation (initial movement of dust
particles) is observed
4


Dust lift-off of dust particles commences
Major particle dust lift-off occurs
These stages for typical coal samples have been
observed to occur at the following wind speeds;
 Saltation: 5 – 7 metres/sec
 Dust lift-off commences: 7 – 9 metres/second
 Major particle dust lift-off occurs: 9 – 12
metres/second
6.3 Chemical surface veneer treatment
The alternative of applying a chemical veneer
to the stockpile surface as a one off treatment
has been extensively examined and has been
found to be more effective than water
application at regular intervals.
Veneer treatment, involves the application of
chemical in water solution to the stockpile surface,
forming a surface crust to achieve resistance to
dust lift-off during periods when the surface is
exposed to high velocity wind.
The mass of dust lift-off from typical coal types
following one-off surface treatment with chemical
veneer has been significantly reduced compared
with two hourly application of water spray.
The procedure is in operation at Australian coal
and iron ore port terminals under extreme weather
conditions, and is now implemented at the
Lyttelton Port Coal Terminal in New Zealand.
Wind tunnel tests on typical iron ore products
indicated the following mass of dust removed;
 Nil treatment – 200grams
 Water spray two hour intervals 10 grams
 Chemical surface veneer – nil dust removed
Figure 5: Wind tunnel with two sample trays
For cost effective management of stockpile dust
emission, a combination of surface water spray and
selective application of surface veneer treatment is
now being adopted at major bulk port terminals
6.4 Protocols for timely
stockpile surface veneer
application
of
Protocols have been developed to use Bureau of
Meteorology hourly wind speed forecast to apply
surface veneer in advance of conditions that have
the potential for adverse dust emission.
These protocols are in use at the Dalrymple Bay
Coal Terminal for the timely and cost effective
application of surface veneer to coal stockpiles.
The combination of water spray and selective
application of surface veneer, together with having
moisture content of each coal type above DEM,
has resulted in a reduction in dust emission.
The reductions have occurred during a period of
increased Terminal throughput (Dalrymple Bay
Coal Terminal 2010)
P2 / Louisa Creek ‐ TSP um/m3
140
120
P2 TSP
Total Suspended Particles (ug/m3)
100
80
Introduction of veneering and second water truck
60
40
20
0
Figure 6: Dalrymple Bay Coal Terminal dust deposition showing reduction in dust emission following DEM moisture
content for all coal types and introduction of stockpile surface veneer treatment, during 25% increase in Terminal capacity
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8. Rail Transport Dust Emission
.
8.1 Dust emission from rail wagons
The key factor that contributes to dust emission
from wagons is the speed of air passing over the
bulk surface. This is influenced by train speed and
ambient wind speed. Other factors found to
contribute include:
 Bulk product properties such as dustiness,
moisture content, and particle size
 Bulk product load profile
 Transport distance
 Surface exposure to wind
Application of the research has provided a basis for
Australia’s coal and iron ore industries to meet dust
management
sustainability
objectives
while
achieving significant increases in export levels to
meet International market growth.
Aknowledgments
The assistance with laboratory test procedures by
Miroslav Djukic and other staff at TUNRA Bulk
Solids Research Associates, University of
Newcastle, is acknowledged.
8.2 Coal wagon surface veneer treatment
References
Extensive studies have been conducted for
Queensland Rail, who provides rail transport of coal
from mines to all port terminals in Queensland. The
objective was to provide improved management of
dust emission from coal trains, to meet upgraded
requirements of Department of Environment and
Resource Management Queensland.
Djukic M and Planner JH, 2008, ‘Determination of
the Dustiness Characteristics of Bulk Solids
Through the Use of Experimental Procedures and
Test Apparatus’ Bulk Europe 2008 Conference
Prague, Czech Republic
Research included wind tunnel studies using 1:50
scale model coal wagons at University of Sydney,
and dust lift-off studies to confirm the effectiveness
of surface veneer applied at mine site loading
facilities. (Djukic M and Planner JH, 2010)
The outcomes from the studies are leading to
progressive installation of equipment at selected
Queensland mine site rail loading facilities to apply
surface veneer chemical to coal in wagons, prior to
departure for port terminals and other end users.
9. Conclusion
A review of current coal dust management practice,
including the application of the research described
in this paper, has been conducted for the
Australian Coal Industry. (Planner 2010)
Dust emission management procedures based
on the understanding of each product’s unique
dustiness
characteristics,
are
being
implemented at major mine to ship
transport systems in Australia.
This approach involves tackling the problem of dust
emission at the source by understanding and
treating the dustiness characteristics of each
individual coal type or iron ore type.
Successful implementation of the research has
been verified by on-site air quality measurement to
confirm compliance with authority health standards
Dust nuisance effects to adjoining communities are
being minimised to an acceptable level.
CASANZ 2011 Conference - Auckland - 31 July - 2 August 2011
Paper 203
Djukic M and Planner JH, 2010, ‘Evaluation of
Dust Emission from Coal Wagons’ Bulk Europe
2010 Conference held in September Glasgow,
Scotland
Dalrymple Bay Coal Terminal 2010, “Stockpile
Veneering Update – An Overview of
Performance Since Introduced to the Site”,
DBCT P/L
Katestone Environmental 2010, “NSW Coal
Mining Benchmarking Study: International Best
Practice for the Prevention and/or Minimisation
of Emissions of Particulate Matter from Coal
Mining” NSW DECCW
Planner J.H. and Jackson P, 2001, Dust
Management at Dalrymple Bay Coal Terminal”
7th International Conference on Bulk Materials
Handling and Transportation, University of
Newcastle
Planner J.H. 2004, “Improved Management of
Dust Lift-off from Coal Surfaces during
Stockpiling and Rail Transport” 8th International
Conference on Bulk Materials Handling and
Transportation, University of Wollongong
Planner J.H. 2007, DBCT P/L & BBI “Test
Program for the Evaluation of Potential Health
Effects of Coal Dust in Drinking Water from
Rainwater Tanks in the Hay Point Area
Queensland”
Planner J.H. 2010, “Coal Dust Control
Techniques – Review of Current Practice”,
ACARP Project C19007
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