10 Good Reasons Not to Build Your Own Spray System for Dust Control
Good Reasons Not to Build Your Own Spray System
I have often fantasized about running an ad that
read, "Here's the cheap hunk of junk spray system you always
wanted". Why, because the last
thing in the world most plants want to spend their money on is dust
control. I've had a plant manager rip up
my literature and a quarry owner storm out a meeting because of their anger and
frustration over regulation that requires them to protect the environment. Our
biggest competitor at NESCO is the plant that decides to build and install
their own spray system. I've seen a few
that are well-designed, but hundreds that aren't.
If NESCO built that cheap spray system, we would've
been out of business years ago.
Why? Because when that system
didn't control your dust, got your stone too wet and broke down all the time
you wouldn't remember that's the system you wanted but only that I was the guy
that sold it to you.
Thankfully, there are plenty of mines and quarries
that see the value in quality equipment that is designed to last in an abusive
But, if you're still thinking about building your
own system, think twice. Here are 10
good reasons not to do it:
1. If you do it right, you won't save any
money. If you build a well-designed,
high pressure spray system you won't save any money compared to commercial
system. NESCO builds systems with
quality components designed to withstand an abusive mining environment. If you use the same components and figure in
all the labor that went in to sourcing the components, purchasing the materials,
constructing the pump module and
installing system, the savings just aren't there.
2. If you do it wrong, it'll cost you
production. If you build a cheap,
low pressure system you'll save money compared to a commercial system but
you'll pay for it in lost production. For
lack of pressure and adequate controls, they add so much water that they blind
screens, cause belt carryback and throw products out of spec. Shutting a 500 tph plant down for an hour or
two to clean screens could cost you $1000 to $2500 a day! That will wipe out the savings in your do-it-yourself
spray system in a few weeks.
3. Whose going to build it? Most plants these days barely have enough
manpower to keep production equipment operating and don't have the manpower to
spare to design, build and install a spray system.
4. Whose going to fix it? When your DIY system breaks down - and it
will - there's no manual, there's no spare parts list, there's no replacement
parts in inventory. The odds are the
employee who got stuck designing and building the system has moved on and no
one knows where to go for parts or service.
5. It is rocket science. I've been listening to people tell me for 30
years that building a spray system isn't rocket science. Well, guess what - designing and installing a
spray system that will knock down the dust and won't screw up production is
just as much rocket science as designing and installing a crusher or any other
piece of production equipment. It
doesn't take any talent to dump enough water on the stone to kill the
dust. Making sure you've got the right
nozzles in the right spot at the right pressure with the right kind of controls
that won't cost production does.
6. There's no guarantee it will get you into
compliance. If you're building a new
plant, you've got 180 days after the plant achieves full production to pass a
visible emissions (VE) test. What if
your system doesn't pass that test? What
are you going to do then - just dump more water onto the stone? You'll pass the test but you won't sell those
off-spec products. NESCO guarantees
compliance by offering an Emissions Control Warranty with every DustPro System.
7. Make dust control our problem
- not yours. Who gets the blame if
your DIY system turns out to be a disaster that gets the rock so wet that you
can't screen it or make spec products?
You do. If we screw up, it's on
8. Regulators don't trust you. They'd rather see a commercial system
installed by experts.
got better things to do. Time spent
on designing and building a spray system is time lost on projects that improve
10. Support small business - when you imitate,
we can't innovate. Companies like NESCO
that sell dust control aren't General Motors. We are all small or even, micro, business
that sell into a niche market. Mining
companies intent upon driving costs down at the expense of small businesses dry
Operating Spray Systems in Cold Weather
Winter is right around
the corner and using spray systems to control dust in freezing weather can be a
real challenge. As
a practical matter, NESCO spray systems can be operated at temperatures as low
as 25 0F as long as the water is moving. Below 25 0F nozzles and other
exposed metallic parts will begin to freeze even if the system is on-line.
some guidelines for cold weather operation:
1. Install a thermometer to alert the
operator to freezing temperatures.
2. Inspect spray nozzles daily to make sure that
they are not plugged or frozen.
3. Inspect the pump daily. Verify that the heater is working and that
the water inlet line is not frozen.
4. Minimize the number of spray lines in service. In freezing weather it will not be possible
to use spray lines at feed hoppers where ice can form on sidewalls. Use only essential spray nozzles.
5. Make sure that nozzles are properly targeted. Nozzles should not spray on steelwork or
6. Drain connecting hose or pipe immediately after they are taken
out of service. Do not allow water to
sit in hose lines and spray manifolds.
7. Verify by visual inspection that no water remains in
8. Keep all drain valves open after the system has been
prevent any residual water from freezing and cracking the valve.
9. Make sure that water lines run straight and true and
that drain valves are located at all low points. Bends, loops, and kinks in hose lines will
make lines more difficult to drain in cold weather.
can be equipped with the following accessories to purge and protect hose lines
in cold weather:
System: This system uses compressed air to blow water out of
connecting hose and spray nozzles after the spray line has been shut
off. When the operator uses the remote panel to switch a spray line
from the "Run" to the “Purge” position, that line will automatically
purge for a preset period of time that depends on the length and diameter of
the hose or pipe. The purge cycle can be repeated as often as necessary.
Injection System: This system operates in conjunction with the air
purge and is designed to prevent any water remaining in the hose, plumbing,
or spray nozzles from freezing. We developed this system because once the
lines are blown out with compressed air, a small amount of water may still remain
in drain valves or spray nozzles. It uses a metering pump that
automatically dispenses glycol into output hose lines after they have been
blown out with air. When the operator turns any output line to the
“Purge” position, three separate timed operations occur. First, the air purge
blows out the line. Second, the metering pump injects glycol (0.2 to 0.5 gal.)
into the line. Third, the controller turns the air purge back on to blow the
glycol through the connecting hose and out to spray nozzles. This coats the
interior of the line with glycol so that any water that collects in a drain
valve or nozzle will not freeze.
the air purge and anti-freeze injection systems do not permit continuous
operation in freezing temperatures. They are designed solely to
purge and protect hose lines and spray in cold weather.
only two ways to operate a spray system continuously in freezing temperatures:
- The system must
be housed in a heated and insulated enclosure and output lines and spray
bars are wrapped with heat tape and insulated.
- The system must
be housed in a heated and insulated enclosure and the pump is supplied
with an aqueous solution of a non-toxic glycol or corrosion inhibited,
Taping and Insulation
can be wrapped around the pipe or hose to prevent it from freezing. Heat
tape is sold in various wattages and we generally recommend a 5 watt per foot self-regulating
heat tape. This type of heat tape is thermostatically controlled and should be
set to power on when the temperature approaches 32 0F. The heat tape is wrapped around the water
line and number of wraps or turns per foot of heat tape will depend upon the lowest
temperature the system will be exposed to. The heat tape also requires
an independent power supply. For example, 1000 feet of 5 watt/ft heat
tape will require 5KW of power. Heat tape and insulation could run
anywhere from $15 to $30 per foot depending on the temperature the water lines
will be exposed to and the type of heat tracing and insulation used. Since
the heat tracing is subjected to an abusive mining environment, we recommend a
high quality fiberglass insulation that is steel-jacked to protect it from
falling rock or other items that might damage it.
economics of heat taping favor large mineral mines, like gold, silver or copper
that have to run 24/7 in any kind of weather that can justify the expense. For a typical 500 tph aggregate crushing and
screening plant with 1500 ft of pipe or hose employing 3000 ft of tape, total
installed costs could range anywhere from $45,000 to $90,000. That’s a lot to spend up front, but it may be
the most cost-effective option over the long haul.
a couple of links where you’ll find information about the design and
installation of heat tape:
It is also
possible to purchase heated hose which is pre-fabricated with insulation and
coated with a durable plastic. Technical Heaters, Inc. is one manufacturer and
here is a link to their website for more information:
two types of anti-freeze solutions that could be used to replace water when the
system is operating in freezing weather - glycols and brines.
In the U.S.
the only glycol approved for use as anti-freeze is propylene glycol because it
has low toxicity and low volatility. Here is a link to the freeze point
curve of propylene glycol:
diagram shows that you need about 20% glycol in solution with water to reduce
the freeze point to 20 0F (-7 0C). We use a 60%
glycol/40% water solution for our glycol injection system. Propylene
glycol is commonly sold as a 60/40 mix because that is about as concentrated as
you can get before viscosity starts to pose pumping problems. It sells in
bulk for about $3 /gallon depending on purity so you could be looking at
treatment costs on the order of $1 to $2 per ton depending on the concentration
required. The high cost of propylene
glycol has inhibited its widespread use.
many other glycols available including waste materials and you should check with
your environmental agency to see what is approved. You might also check
with chemical companies that sell freeze conditioning agents, also known as ice
crystal modifiers, to the coal industry where they are widely used to prevent
coal from freezing in railcars. These are usually solutions of salts like
sodium acetate or urea with a bit of glycol and water mixed in.
and Magnesium chloride brines are very effective anti-freeze agents which are
much less expensive than glycols. However, they may be corrosive to spray
system components. We have a couple of
customers using brine without incident but our systems use brass, bronze or
stainless steel plumbing. If your spray
system uses black iron or galvanized components, they are going to corrode
unless the brine solution contains a corrosion inhibitor.
solution of calcium chloride in water, for example, will depress the freeze
point to about -4 0F (-20 0C). Concentrated liquid brines
(32%) sell for anywhere from about $0.70 to $0.90 per gallon - about a third
the price of propylene glycol. It may be possible to find a waste brine
that is a byproduct of gas drilling that is even less expensive. For a
20% commercial brine solution to operate at -4 0F (-20 0C),
treatment costs would run about $0.20 per ton assuming it was sprayed at an
addition rate of 0.2% (about 0.5 gal/ton).
For a 500 tph aggregate plant producing a total of 30,000 tons over 60
days of winter operation, treatment costs for anti-freeze could range from
$6,000 to $12,000. For a plant like
this, the anti-freeze option looks much more cost-effective than heat
remember that anti-freeze agents can alter the chemical properties of aggregate.
Glycols are set-retarders in concrete and brines are set accelerators. At mineral processing plants, the anti-freeze
could potentially upset downstream processes like froth flotation or waste
water treatment. It is unlikely that the small concentration of anti-freeze
agent present in the stone or ore could cause a problem but better to be safe
and sorry and take a hard look at potential side effects.
How to Save Dollars on Dust Control
Times are tough and cost control is
the key to profitability. Air quality
standards are a fact of life and quarries have little choice but to spend money
on control measures that will keep them in compliance. But why spend more than you have to? .
What’s the difference between a
million dollar and a ten thousand dollar race horse? Does the former run one hundred times faster
than the latter? Of course not. The difference is the nose that gets across the
finish line first. In other words, it’s
the little things that count. If you
want to save money on dust control, do the little things that will add up to
Here ten money-saving tips to
control dust from roads, piles and crushing plants.
The slower a vehicle travels the
less dust it produces. On most roads,
vehicles that travel at 15 mph do not produce appreciable dust emissions. A
speed limit of 10 mph is even better. Is a 15 mph practical for haul routes? If trucks can get stone up to the primary
crusher fast enough at 15 mph, it makes sense.
If they can’t, calculate the minimum speed required to the maintain
production rate and set speed limits accordingly. I’ve seen haul trucks race to a primary
crusher at 40 mph in a cloud of dust only to sit there for 10 minutes waiting
to dump – that’s what you want to avoid.
No. 2 - Enforce Speed Limits
Posted speed limits won’t reduce
dust if they aren’t enforced. That can
be tough if truck drivers aren’t your employees. Speed bumps can help trucks to observe speed
limits but banging tailgates can cause a noise problem. Rumble strips are more likely to slow trucks
down without causing gates to bang. Posting
and rigorously enforcing speed limits is the best way to reduce dust emissions
and the frequency of treating unpaved roads.
Plant management has to set the example.
If you blast around the plant in your pick-up, don’t expect anyone else
to slow down.
Shorten traffic routes as much as
possible. Fewer vehicle-miles traveled
means less dust in the air and less road to water or chemically treat. Use flags or other markers to delineate
traffic areas and install concrete barricades to make sure trucks do not wander
off of designated routes. Keep paved roads clean by restricting access to them
from unpaved roads.
No. 4 – Improve Road Structure
Poor construction, bad drainage and
lack of maintenance all aggravate dust emissions and track-out. Inspect roads to make sure they have a proper
crown, a good mix of fines and aggregates and a well-compacted surface. When surface material has more than 30% silt,
dust control measures will work but will not be cost-effective. Put some chips or other coarse aggregate down
to reduce the amount of silt on the surface.
This will reduce the frequency of treatment and the amount of water or
chemical used per square yard.
No. 5 - Use Road Dust Suppressants
A wide variety of chemical additives
are used as road dust suppressants. Just
about every sticky, gooey or gummy chemical you can imagine has been used to
control road dust. They can reduce the
frequency of treatment to the point where they are less costly than routine
watering especially in dry, arid environments where water is hard to come by. Vendors may be willing to provide a free
trial to let you gauge effectiveness of chemicals and determine cost savings.
If you are currently using chemicals
to control road dust, try to use a waste product for this purpose. For example, waste brine produced from oil
and gas wells can be just as effective as more refined and expensive products. Pulp and paper plants, steel mills, oil refineries
and chemical plants may all be sources of waste or off-spec materials that can
be used on unpaved roads.
No. 6 – Replace Tankers with Sprinklers
Install a stationary sprinkler
system instead of using a mobile tanker for road dust control. It can cost in excess of $100,000 annually in
capital and operating costs to employ a mobile tanker to water roads in a large
quarry. Stationary sprinkler systems can
significantly reduce these costs depending on the distance that requires
watering. Simple computer controls can
be used to optimize the frequency and duration of treatment. Just make sure that the sprinklers are
protected from errant trucks and can be drained in cold weather.
No. 7 – Train Loader Operators in Control Measures
Loaders are the most active vehicles
in quarries. Train operators to take
personal responsibility for dust control.
That means not overfilling buckets and spilling stone as they load trucks. Avoiding sharp turns and rapid accelerations
also helps to keep dust down. Loading
out from the lee side of a pile on windy days can also make a big
difference. In most cases, dumping
quickly can help to reduce the amount of dust that gets into the air.
No. 8 - Choke feed crushers
Good operating practice can not only
reduce dust but also improve production.
Choke feeding crushers is one example.
Crushers, particularly horizontal or vertical shaft impactors produce
less airborne dust when they are operating at capacity because they are moving
less air. Some plants I’ve seen are a
Frankestein mix of mis-matched equipment slapped together with screens or belts
to small to keep up with their crushers.
Dust produced from impactors that are operating at less than 50% of
capacity is almost impossible to control.
No. 9 - Avoid Interruptions
Avoiding interruptions in process
flow also reduces emissions and keeps production rates up. Crushers that are “windmilling” an put ten
times the dust into the air as they do when they’re loaded. The most common reason for intermittent
operation is the lack of sufficient haulage to sustain primary plant
operation. Stone runs through the plant
in a burst of production followed by a burst of dust.
No. 10 – Enclose Dust Sources
Enclosing dust sources is one of the
most cost-effective ways to reduce emission levels and your reliance on more
expensive controls like wet suppression systems or baghouses. The EPA estimates that partial enclosure of a
dust source like a transfer point or hopper on three sides with a cover has a
control efficiency of 70%. Adding a
simple rubber dust curtain at discharge points also helps to contain
emissions. Make sure that belt skirting
is in good shape and there is enough idler support at load points to prevent
dust and spillage. Workers have their
greatest exposure to respirable dust when they have to shovel or bobcat
spillage caused by leaking skirts. Much
of this work can be accomplished using scrap steel, old belting and a little
Conclusion – Implement the least expensive control
A cost-effective dust control plan
designed to comply with air quality standards at the lowest possible cost
requires the use of good operating and engineering practices combined with a
proper wet suppression (or dry collection) system. Good operating practice means training operators
to take personal responsibility for minimizing dust. Training them to do so is barely a blip in
the budget and can have a big payoff.
Good engineering practices that emphasize the containment of dust
sources can often be implemented with in-house labor and material. Do the least expensive things first. You’ll find that the savings that result will
go a long way in reducing the costs of more expensive controls like wet
suppression and dry collection systems.
Fog Dust Suppression
I get a lot of calls and
e-mails from customers looking for a ”fog” system because they have this idea
that fog systems are able to control dust without adding any moisture to the
process. That’s true, but
there are a lot of practical difficulties and hidden costs.
First, what exactly is a
fog? By definition, a fog consists of
droplets that have an average mean diameter of 10 microns. If the spray system
is not capable of producing droplets with a mean diameter of 10 microns, it
cannot be termed a fog system. There are commercially available systems which
represent themselves as "fog" systems which do not meet this criteria
so you have to be careful. Unfortunately, “fog” is a term that has been used
There are only two types
of commercially available equipment that are capable of producing a fog. The
first uses a postive dislacement pump to produce pressures in excess of 1000
psi and nozzles with an orifice about the width of a human hair. The tremendous
shear that occurs at the nozzle tip produces droplets in the 10 micron range.
The second is air atomization in which compressed air and specially designed
nozzles are used to shatter water into 10 micron droplets.
Fog systems are
designed to suppress only airborne dust and do not add any detectable moisture
to the substrate. Because excessive moisture can decrease screen efficiency,
aggravate crusher wear and cause wet handling problems like belt carryback,
aggregate processing and other material handling plants have every incentive to
keep moisture addition rates for dust control to a minimum. This is why the term "fog" is so
often used as an effective marketing tool.
However, while I’ve
designed and built a lot of fog or air atomizing systems I don’t recommend them
for use in quarry and mining environments for the following reasons.
require a high degree of enclosure for optimal performance. The enclosure is used to create a
"dead air" space in which the fog droplets and dust particles are
able to collide, agglomerate and drop out of the air. For example, a truck
hopper should be completely enclosed on three sides and covered for a fog
system to effectively control dust. Without the benefit of an enclosure, even
the slightest wind will blow the fog off target.
Because they are
designed to suppress airborne dust and add no detectable moisture, they do not
have any "residual effect" that helps to prevent dust from
downstream operations. For this reason, nozzles must be installed at every
drop or transfer point. This means more
nozzles and can significantly
systems require a very clean (city) water supply. Fog and air atomizing nozzles have very fine
orifices and are much more susceptible to pluggage than conventional spray
nozzles. In the case of fog systems which use positive displacement pumps, any
suspended particulate in the water supply will aggravate pump wear.
4. In the case of
air-atomizing systems, we have seen instances where the injection of large
amounts of compressed air required to produce fog droplets pressurize the
enclosed source area causing mist and wet fines to blow out of the area and
actually aggravate emissions.
displacement pumps used to produce fog require periodic (monthly) lubrication. The vertical stage centrifugal pumps we use in
lower pressure misting systems is self-lubricating and requires no regular
Air atomizing systems
require significantly more maintenance than a conventional water spray system.
Air atomizing systems use regulated water and air flows and pressures to
produce an atomized fog spray. With all the clanging, banging and vibration in
a typical plant, it is not unusual for these settings to drift. Too much air
and the nozzle fails to atomize enough water to maintain the spray, too little
air and the spray becomes too wet and droplet size increases.
Air atomizing nozzles
are significantly more expensive than conventional and fog nozzles. Prices for
fog nozzles range from $8 to $15. The typical flat spray nozzles we use in a
conventional water spray system in the same price range. Air atomizing
nozzles are much more highly machined and cost 5 to 10 time as much. The
fact of the matter is that nozzles get damaged and wear out and air atomizing
nozzles have a much higher replacement cost.
Fog systems require the use of more
expensive hose and hydraulic fittings. The conventional water spray systems
we’ve designed operate at 200 psi because that is about as high as you can go
with conventional pipe and hose fittings. At pressures in excess of 300 - 400
psi, hydraulic hose and fittings are required.
systems in particular and air-atomizing systems to a lesser extent are not
designed for use in an abusive mining environment. Both systems were originally developed for
evaporative cooling applications and that remains their major market. Air
atomizing systems were the first to be adapted to dust control in the '70's.
Raring Corporation introduced the "Sonic" system in the U.S. and
installed many of these in quarries (all of which have been abandoned - I know
of no quarry in the U.S. using an air atomizing system). We, in fact, were contracted to install a
Sonic system in 1990 at a quarry in New Jersey. They were termed
"sonic" nozzles because these air atomizing nozzles were equipped
with a resonator tip that promoted fog droplet atomization. After one week in
service, every resonator tip had been damaged by errant stone. In our 23 years
in business we have installed three or four air atomizing systems of our own
design (no resonator tips). All of these have been used to produce a curtain of
mist at an enclosed truck hopper.
As for fog systems, they were also adapted to
dust (and odor) control in the early '90s and their major market in this regard
has been enclosed trash transfer stations where arrays of fog nozzles are
installed in the ceiling to settle dust and deisel exhaust on the tipping
floor. We have used fog systems in warehouses for the same purpose and recently
completed a large installation for Pacific Coast Materials near Sacramento, CA -
a large clay pipe manufacturer. We also use a fog system in our line of
SpreadKleen products that are designed to suppress dust from trucks spreading
lime, ash or portland cement for soil stabilization. They work well in enclosed
applications but we do not recommend them for quarry applications because they
just don't hold up. Positive displacement pumps simply don't last because they
have to operate in a dirty environment with poor water quality where production
machinery is always the first priority of maintenance.
I have no axe to grind with fog and air atomizing systems
technologies - they work well in the proper application but there’s no getting
round their principal problems of high maintenance, the need for clean water
and poor reliability.
Now, conventional spray systems (and I don’t mean a garden
hose stuck in a crusher) that are designed to operate at 200 psi and use conventional spray nozzles will produce an atomized mist with droplets
distributed within a 50 to 500 micron range. This is also the size range for
most of the visible dust produced in a crushing and screening plant. As a
result, the system affords an excellent match between dust and droplet sizes
that enables the system to suppress a wide range of particulate. Now, we can go
to impingement nozzles which will consistently produce droplets with a mean
diameter in the 40 to 60 micron range (mayber 5-10% of droplets in the 10
micron range) but that's about as fine as we can get.
Conventional spray systems like NESCO’s DustPro are designed to
control dust in two ways:
It produces a higly
atomized mist that suppress airborne dust and
adds from 0.2% to
0.5% by weight water to the process to prevent dust emissions from
In the instances where we have been able to track water addition
rates, we find our customers are operating in the 0.2% to 0.3% range. The addition of moisture to the process
reduces the dustiness of the stone and eliminates the requirement for nozzles
at every drop point. We have found empirically that the addition of less than 0.5%
moisture rarely leads to reduced screen efficiency, aggravated crusher wear or
wet handling problems. The only exceptions to this have been at quarries
processing a very soft, chalky limestone or materials contaminated with large
amounts of fine clay. In both cases, we have been able to resolve these
problems by installing smaller nozzles and improving operator training.
When I began NESCO in 1989, I had the benefit of previously
working as a consultant to mining companies and much of this work was designing
water spray systems. At the time, (early '80s) there was no manufacturer of
water spray systems for quarries. There were chemical systems that were widley
used in the coal industry, air-atomizing and fog systems for special
applications but, surprisingly, no company sold a simple, reliable water spray
system. Many plants simply built their own systems.
At that time, the main
problems with these water spray systems were:
Low pressure - most
systems operated at 40 - 80 psi and had to add as much as 1% to 1.5% water to
acheive the desired level of dust control. Such low pressure systems could not
suppress fine airborne dust because droplet size was too large. It was these
low pressure water spray systems that gave water spray systems a bad name - the
garden hose in the crusher approach.
Manual control -
operators had to leave their production tasks to open and close valves and were
unable to adjust the amount of water in response to dust levels. Multi-million
dollar, highly automated production plants were saddled with rudimentary spray
systems that either added too much or too little water for dust control because
operators could not respond fast enough to changes in the production process or
Cheap construction -
This was a big problem - companies were reluctant to invest in quality
pollution control equipment because it did not contribute to production. This
kept the accountants happy but maintenance personnel had to deal with constant
So we designed the DustPro to overcome these deficiencies. First,
we used a 200 psi pump so that we could improve droplet atomization and
increase penetrating power. This enabled us to reduce moisture addition
rates to values that would not affect screen performance or crusher wear.
Secondly, the DustPro is electronically controlled. The operator
can remotely switch nozzles in independent spray zones on or off in response to
dust levels. The same man who controls production equipment also controls the
spray system. This enables the operator to maintain an optimum moisture
additon rate - just enough to control the dust but not so much as to cause
screen blinding etc.
Thirdly, our equipment is built to last. All the plumbing
is brass or bronze and the pump has stainless internals. The system uses the
best components we can find because it has to hold up in a very abusive
environment. I visited a LaFarge plant outside of Chicago last month where we
installed a system in 1992 that was still in excellent operating condition.
I believe that conventional water spray systems represent the best
compromise between performance, ease of operation, and reliability in an
abusive mining environment. If you have
to have a fog system make sure that you have the benefit of an enclosed source area,
are prepared for higher maintenance costs, have a very clean water supply and
use only heavy-duty components.
Welcome to my first blog post. I hope that this blog will become a forum to provide you with information about dust control that you’ll find helpful. Sure, we manufacture and sell equipment but I’m not here to hype our products. I’ve been involved in dust control since 1978 - first as a chemist developing additives for dust control, then as a consultant putting together dust control plans and preparing permits and, since 1989, designing wet suppression systems. I’ve been in just about every major industrial plant and mine in the US and then some including coal mines, steel mills, copper mines, quarries and shipping terminals.
All that experience has taught me that dust control is a lot more than just having the right piece of equipment. It’s also about good operating practice – training operators how to minimize dust and take personal responsibility for controlling emissions. I’ve seen too many plants spend tens of thousands of dollars on a spray system or baghouse only to be fined because an operator did something stupid. Years ago, we installed a spray system in a truck loading facility at a transshipping terminal. This company had spent lots of money on an enclosed bay where trucks were loaded. It was vented to a baghouse, equipped with curtains, and now with a brand new spray system around the perimeter of the bay door where the loader filled the trucks. So, I’m standing there with the owner to start the system up and show him what it can do when a big ball of dust billows up from behind a warehouse. Turns out that a trucker didn’t want to wait in line to fill up and got a hold of his buddy on a loader who agreed to sneak behind the building and load him up. Well, guess who just happened to be passing by the plant when this happened – a state EPA inspector on his way to his nearby office – who wheeled into the plant and fined them $10,000 on the spot.
It was a real shame. The plant had spent all this money only to have it foiled by an operator who violated best management practice. Even worse, it cost the loader operator his job.
Training operators how to minimize dust in their daily operations is one of the most-effective and least expensive control measures. It doesn’t cost a dime and can really help to prevent fines and citations.
Good engineering practice is another way to control dust and keep costs down. Enclosing transfer points and installing dust curtains are easy to do and can often be done using in-house labor and material and go a long way to reducing dust. I’ve seen a lot of new plant construction where there isn’t enough idler support under load points or where belts are loaded to close to the tail pulley which leads to fugitive dust and spillage. The poor schmuck that has to bobcat or shovel that spillage up is going to get a noseful of dust. In fact, that’s where most of the exposure to respirable dust occurs – when operators have to clean up the plant.
Look, good dust control is just good process control. If it’s not going up in the air or spilling on the ground, it’s going into a truck, barge or railcar and and make money. In these tough times, it’s more important than ever to keep the costs of dust control down and production up.
So let’s hear your questions, comments, and suggestions about what we can all do to protect our health and improve the bottom line.
Thanks to Dave Carlson of Michigan Tech and Ken Cunningham of Sargent Sand as well as all the other organizers of the 17th Annual MSHA Winter Workshops of the Great Lakes District Council of The Holmes Safety Association, January 17-19. I gave a presentation on dust control at the meetings in Gaylord and Okemos, MI and was joined on the program by Paul Cook of MSHA’a Small Mines Office. Paul spoke about current MSHA concerns and trends and his office is a great resource for any mining company trying to wade through MSHA regulations. Chuck Rehmann spoke about the hazards of silica containing dusts and Andy Crause of Bureau Veritas North American Health, Safety and Environmental Services gave a terrific presentation about dust sampling methods and costs.
I’ll be at the AGG1 Academy at the AGG1 Forum and EXPO in Charlotte on Wed. March 14 at the Charlotte Convention Center in Charlotte NC to present a program on “How to Control Dust”. This program discusses how dust emissions from mining and material handling operations arise from four major sources: unpaved roads, paved roads, material processing and stockpiles. The presentation describes a method for developing a dust control plan that relies upon a combination of good operating and engineering practices coupled with wet suppression and dry collection systems. Based on the philosophy that good dust control is good process control, this method is designed to comply with regulation without sacrificing productivity. By treating dust control as a problem of process control rather than a regulatory issue I try to show plants how to employ low-cost, low-efficiency controls first in order to reduce reliance upon more expensive and efficient control measures.
These seminars are one of my favorite things to do and I’ll go anywhere anytime to spread the gospel about dust control.
Jan. 30, 2012