November 2001
Pit Sense--Reserve Estimation: Getting Figures Truly Written in Stone
Gravitas Superabit, Part 2--Selecting a Roof Bolting System
Success in the Field--Fox River Implements Metso Turnkey Operation
Maintenance Matters--Battery Battles
Reserve Estimation: Getting Figures Truly Written in Stone
By Larry Bolling, P.G.
A basic goal of every mine plan is to maximize mineable reserves. Every
quarry manager or pit supervisor probably has some idea of the quantity
of reserves remaining at their site, but exactly what is this idea based
on?
In general, reserves consist of that portion of available geologic resources
that can be economically extracted. Physical features such as landforms,
geologic features, groundwater levels and bodies of surface water place
obvious limits on mining existing resources. Ownership and permit constraints
further limit exploitable reserves. Even after accounting for all these
issues, the reserves must still be of acceptable quality to meet applicable
product specifications. All these factors conspire to whittle away at
the volume of reserves that are actually mineable and worth going after,
underscoring the need to wisely manage those reserves that remain.
Performing a reserve estimate can be as simple as measuring several areas
on a scaled map and assuming an average thickness of material, or as complicated
as computer modeling of rock type and quality data for every 50 ft. block
of material on a property. In practice, most estimates fall somewhere
in between these two extremes. The purpose of the reserve estimate and
the amount of information that is available generally determine the scale
of the effort expended on the project.
The reasons that compel companies to perform a detailed reserve estimate
are varied. Sale or purchase of a mining operation or valuation of a mining
property can trigger a reserve study. Questions regarding reserve abandonment
or sterilization as a result of overburden disposal, processing plant
relocations and expansions, stream relocations or difficult mining areas
can only be answered accurately through detailed analysis. If quality
of the rock is an issue, a blending plan might be the answer to extending
the operating life of a quarry. Even customers can precipitate an analysis
by demanding proof of the existence and quality of reserves before committing
to long-term purchase agreements.
The first step in estimating reserves is to gather together all the information
that is available on your site, the geologic resource you are mining and
pertinent mining regulations. This might include deed and lease documents;
mining permits; regional or municipal planning and zoning documents; local
mining ordinances; geologic reports from various federal, state and local
sources; water well data; drilling records; and any testing data available.
Organizing and becoming familiar with this information will identify all
the existing constraints on mining, paving the way for a realistic reserve
estimate.
Incidentally, this stage presents a good opportunity to document and preserve
site information for a mining operation. For many operators, just gathering
this information is a major project. The reports, test data, and drill
logs that might be available represent a large investment of your company’s
time and money. Organizing and preserving this information ensures that
the greatest benefit is derived from the investment. There are a number
of ways to consolidate this information, both in hard copy and digitally,
that can make it easily accessible and available to anyone who might require
it.
Once the available information is compiled and organized, it is possible
to identify the gaps in the data. The next task is to identify appropriate
methods to fill in those gaps. Depending on the scale of the information
required, these methods might include aerial photography and mapping,
geophysical studies, drilling test holes, geologic field studies or digging
test pits. Obtaining information to complete a database is the most expensive
part of the entire process. Generally, the level of cost is inversely
proportional to the scale of the information required.
If quality analysis is required, a sampling and testing program must be
developed. The program should provide enough information to augment whatever
data are already available to satisfy the goal of the reserve estimate.
For example, is it sufficient to confirm the existence of half a million
tons of high-quality material, or is the goal to provide a general idea
of the quality available on the entire site? Detailed quality analysis
can get very expensive, due to drilling and testing costs. Concentrate
on the material properties that are critical to your operation, but don’t
ignore other potential problems. Running an occasional sample through
a complete battery of tests can provide a baseline of data for future
sampling programs and might alert an operator of potential problems that
could be addressed before becoming critical.
Sometimes, less costly methods can be used to supplement or confirm information.
For example, test pits completed using an excavator available on site
might be an acceptable alternative to auger holes in overburden or sand
and gravel studies. Air rotary drill holes might produce acceptable material
for testing at a fraction of the cost of diamond core holes. Or, maybe
soundness loss results correlate to another characteristic of the rock
in question, such as absorption. Just be careful not to consider results
from substitute methods as reliable as those obtained using the best method
available.
The distance between data points depends on the required degree of accuracy
of the study as well as the geologic setting. The end result is always
a compromise between cost and confidence. Seek the input of a qualified
person who is familiar with the formations under investigation, as well
as the quality issues faced by producers, to help develop an appropriate
sampling and testing program.
After sufficient information is available, analysis can begin. Reserve
quantities can be computed based on location, quality and scheduled availability.
Computer modeling, performed properly, can provide a wealth of information
in formats from spreadsheets to colored maps, tailored to the operators’
specific needs. Keep in mind the standard computer adage: Garbage in,
garbage out. Modeling methods must be appropriate for the data being analyzed
and must respect all constraints you worked so hard to identify at the
beginning of the process.
The end result of this effort is to provide you with the information to
satisfy your original goal. Weeks of work might even be reduced to a single
number: the tons of material available for mining at a specific site.
Take the necessary steps to develop an accurate reserve estimate for your
operation, and it can result in figures that truly are written in stone.
Larry Bolling, P.G., is a geologist with the Industry & Environment Group of Morris & Ritchie Associates, Inc.
Gravitas Superabit, Part 2—Selecting a Roof Bolting System
By Jack Parker
Part 1 of this series was a general discussion of roof bolting in stone
mines. In this part, we go on to actually selecting a system.
The first question to ask and answer is this: Do we really need roof bolts?
If the need is not obvious, but an authority decrees that “This roof
shalt thou bolt,” it would make sense to ask him to explain why,
and to explain it in simple terms. If the explanation is too technical,
it is suspect.
If roof conditions need help, then see if they can be put right in some
other way, perhaps by selecting a different roof horizon or by changing
orientation of the mine openings. You look for the opportunities.
If the explanation is credible and if there are no acceptable alternatives,
then go forward with some reasonable design approach.
CHOICE OF BOLTS
Here are some generalizations to consider. Not everybody will agree with
all of them. You figure it out.
The first choice is often between mechanical and resin anchorage.
If the function of the bolts is cosmetic, or maybe to suspend occasional
slabs, or to offer some insurance for a short period of time—then
mechanical anchors may suffice. Potential problems are that the serrations
on the shell of the anchor gradually creep into the rock, allowing the
bolt to lose tension; that moisture will cause the bolts to rust; and
that weathering of the rock around the bearing plate will cause the bolt
to become completely ineffective. On the other hand, they should cost
less, and they can be installed without special roof bolting equipment.
Resin/rebars overcome most of the difficulties. Anchorage is distributed
over the grouted length, resin protects against corrosion and even if
the rock weathers away from the bearing plate, the resin/rebar will continue
to hold the rock together. A problem for some folks is that a smaller
hole must be used (to ensure mixing of resin and catalyst) and the rebar
must be thrust and spun into the hole to do the mixing. For long-term
support, the resin/rebar bolt will almost certainly be a better choice.
Cement-grouted bars will perform the same function, but they are most
often used where a large number of holes are drilled. The bolts are then
installed using a batch process for the cement. Resin comes in sausages
and sets up quicker—so the operator gets roof support as he goes,
always working under supported ground.
LENGTH, STRENGTH AND SPACING
The textbooks and much of the literature will tell you that you can “build”
beams by binding the layers or chunks together but, in my opinion, the
end result we, in mining, look for is to prevent the rocks falling—which,
when you work through it, boils down to suspending the potential loose
rock from some stable zone.
I would try to define the zone to be suspended by looking at all of the
roof falls I could find. They might, for example, include 3 ft. of geologically
thin-bedded, blast-damaged shaly limestone, stopping at a more massive
bed.
In this example, the spacing would probably depend on what “looks
right”, i.e., close enough to ensure that few chunks would fall from
between bolts. If rock were likely to fall from between bolts, we would
probably add wire mesh or steel mats to contain it.
Every square foot of that roof would potentially be loaded by 3 cu. ft.
of rock. Limestone weighs around 1 ton per 12-1/2 cu. ft., so, if we thought
that 5-ft. centers would be about right, each bolt would have to suspend
25 sq. ft. weighing 25 x 3 / 12.5 = 6 tons—which could be handled
easily by standard 5/8-in. mechanical bolts or standard 3/4-in. rebars
(but check the specs on all available bolts).
Next comes the question of bolt length, i.e., where is the stable zone?
To determine bolt length, we now try to define the stable zone from which
we can suspend the potential loose rock.
A stable arch? Most falls of roof, even in sand, probably work their way
up to an arch shape, which would be more-or-less stable. There are several
ways to explain that.
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In almost all mining situations, there is some horizontal compressive
stress in the rock mass—and that works to hold the roof rocks in
place. But if that stress is too low, or if the room is too wide, or if
the rock itself is weak—then the roof sags into the mine opening
and a zone of tension develops in the immediate roof. That is the zone
that wants to fall out. But the horizontal stresses now arch up and over
the mine opening, creating a zone of increased compression—hence
a more stable zone.
The shape of that zone is controlled largely by the ratio of horizontal
stress to vertical stress. Within moderate limits, a high vertical stress
forms a high elliptical arch and a high horizontal stress forms a low
elliptical arch, as in these sketches (Figure 1).
We could recognize local conditions by examining all of the falls of roof,
and/or by drilling observation holes in the roof and examining them to
define the uppermost fractures and separations. We could use a borescope
to find them, or going low-tech, we could use a homemade scratcher. Remember
the scratcher? It is a length of 3/4-in. steel conduit, the last inch
or so flattened, bent over at right angles, then ground or filed to a
sharp, thin point. You can mark it in inches, or centimeters if you intend
to publish the results in Mining Engineering. You shove it up the hole,
then drag it down slowly, “feeling” the walls of the hole. You
should be able to sense smooth rock, rubbly zones and separations. If
you think that you have detected a separation, rotate the tool to make
sure that the crack is present all around—not just a chip off the
wall. Jiggle the tool up and down to get a feel for the width of the separation.
Note the depths to all interesting features. Get sophisticated if you
wish and bear down on the rock and listen to the sound effects: a high
blackboard-like screech comes from fine-grained hard rock, wet shale sounds
like mud and intermediate noises come from intermediate conditions. The
tool was originally called a cracksnagger (Figure 2).
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A somewhat similar situation may exist where the rock is fairly massive,
behaving something like a beam. As the textbook would point out, the underside
of a working beam is in tension, the topside is in compression and somewhere
between top and bottom is the “neutral axis,” an imaginary line
along which the beam is neither in compression nor in tension. We would
want our bolts to be anchored above that neutral axis (Figure 3).
Even in blocky ground there is some hope that a “beam” will
be formed as the blocks key together in compression at their tops, in
what is called a “voussoir arch”—the sort of thing you
used to see in old stone bridges. In this situation, the lower tensile
zone would again be suspended from the upper compressed zone (Figure 4).
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If we stretch that idea a bit, we come close to the textbook idea of
beam building. Look at it this way: if a beam is too thin it will sag
and “buckle through” because the neutral axis is above the top
of the beam, but if we can pin several such beams together, to form a
composite beam, then the neutral axis may be within the composite beam—and
it may survive. But perhaps it is not truly a beam structure, because
of the natural cracks and weaknesses in most rocks, but a grouping of
thicker blocks, can now form a thicker voussoir arch, which may be stable
(Figure 5).
If, after doing your best, you find the roof on the floor with the bolts
sticking up like a pincushion, then the odds are that the bolts were not
long enough (Figure 6).
And if, even after diagnosing and correcting pre-existing problems, not
all of which have been mentioned—like gas or water pressure in the
roof, and others I am leaving for you to work out—there may be special
situations which require special treatment.
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A recent example occurred in part of a mine where the roof was cut by
two sets of joints, parallel in trend but dipping in opposite directions,
to form long, heavy wedges of rock in no way bonded to each other (Figure
7).
The first step would be to orient the mine openings so that the great
majority would cross these joints at right angles (to minimize the length
of the wedges), to make those openings that are parallel to the joints
as narrow as possible and to stagger the intersections. Then we work on
the roof bolting—and we have to bind those wedges in place as early
as possible with steel straps running from bolt to bolt across the joints.
And we would have to sketch some cross-sections of the geology and the
roof falls to determine bolt length (Figure 8).
OK, so we have found a stable zone in which to anchor, now we have to
get the anchorage. The general idea is that each bolt will have to support
our calculated load, with a bit to spare.
PULL TESTS
The bolt manufacturers and the other experts will probably recommend
pull tests—to promote the value of their wares, but beware of pull
tests because they can mislead. Let me give examples.
This is how they are supposed to work: a bolt is installed and a hydraulic
jack is affixed. Tension is applied and, at fixed intervals, say every
ton of load; the movement of the head of the bolt is measured, usually
to the nearest thousandth of an inch. Normally it takes a ton or two to
settle down, and then a fairly regular change is seen with each ton of
additional load, until something different happens, and the trend of the
graph would change. Maybe the steel starts to stretch, maybe the anchor
starts to slip, or maybe the hydraulics are leaking. I have seen the hydraulic
jack bottom out and the tester said, “Wow!” (or something like
that): “That anchor’s not budging!”
The operator may choose to continue to add load, but usually not to complete
bolt failure because that may be sudden and may do damage. News item:
“Sales rep observing pull tests harpooned by 6 ft. roof bolt. Grade
75 bolt broke at 16 tons. Brittle fracture. Combination anchor and bolt
meet specifications. System approved. Next-of-kin to be informed.”
If he, the tester that is, does not choose to continue the test to failure,
then it is a good idea to back off the pressure ton by ton, noting the
displacements again—to find out how much permanent displacement there
has been. But beware! Results may not be what they appear to be.
With mechanical anchors, the test result is for short-term anchorage,
but as hours, days, months and years pass, it is not unlikely that they
will become loose—because most of the load is borne on a few sharp
teeth digging into the walls of the bolt hole. You may want to check performance
over a longer time-span, perhaps with a simple torque wrench. Adding a
slug of resin to mechanical anchorage should improve long-term performance.
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The performance of resin/rebars in pull tests may also be misleading,
since they are commonly performed on a fully-grouted bar, maybe 4 or 6
ft. long. That means that several feet of anchorage is available to resist
the pull, whereas that may not be the case in real life (Figure 9).
In Figure 9, a mass of rock about 4 ft. thick appears to be suspended
from a strong upper beam by 6-ft. rebars—so stability actually depends
on the anchorage only in the top 2 ft. of rebar—and we can discount
the top-most few inches of that because there the resin is not likely
to harden.
It is more meaningful to run tests on short lengths of anchorage, say
10 in., 20 in., 30 in. and so on, or to test anchorage on the most probable
working length (the top 2 ft. in the sketch).
And of course the resin manufacturers’ instructions for installation
must be followed.
The same caution should accompany tests of the various “friction
anchorages,” which are usually performed on full-length samples,
whereas the working anchorage may not be full-length.
A typical resin/rebar in a decent limestone should provide about one ton
of anchorage per inch of good resin, i.e., a foot of good resin should
offer about 10 tons of resistance (but we should run the tests). See Figure
10.
Note that resin anchorage, properly installed, may still fail in two ways:
- If the rock is relatively soft, and/or wet and/or smoothly drilled—then the failure is likely to be in the rock immediately adjacent to the resin—the system will slip as the rock shears. After a fall of roof, you will probably see rebars in the rockpile still encased in a smooth covering of resin.
- If the rock is strong—stronger than the resin (which is mostly ground limestone), then excessive load will crush the resin under the deformations on the rebar, beginning at the collar of the hole (or where the load is initially applied) and working its way up the length of the bolt. After a fall of roof, you will probably see pulverized resin on exposed rebars. A remedy might be to expose more resin to the load by using rebar of larger diameter or rebar with larger deformations.
There will probably be heated debate on the question of tensioning resin/rebars.
I am reasonably sure that it is not necessary and often not to be desired.
First—only a few thousandths of an inch of rock movement is needed
to tension the rebar, which means that it will probably happen naturally.
Then there are the problems which accompany pretensioning—too much
torque and partially twisted-off nuts or bolt heads.
Another factor not generally recognized is that immediately after excavation
of a mine, opening the rocks typically relieve some of the stress in them
by moving a little into the opening, much as a pane of window glass might
be bowed after installation (you can see wavy reflections in the glass).
Obviously it would be unwise to push on the glass to straighten it, and
likewise it is unwise to try to force rocks back into their original overstressed
position. Just snug them up! As a matter of fact, it is sometimes best
to design bolting systems that will yield a little, instead of breaking.
But that is a special situation. You may have seen it in evaporite mines—salt,
potash, etc.—where roof beams separate and bow downward several inches
(I’ve seen 18 in. of separation) without breaking. In some of my
photos, those rocks remind me of wet cardboard.
Somewhat reluctantly, let us close now—not having covered the topic
completely—with a summary of the most important steps.
SUMMARY
1. Do we really need bolts? Plenty of mines manage without them. Some spot bolt in special circumstances. Some install cosmetic bolts. Some use an “approved” pattern throughout the mine to avoid confusion, which might come if choices were allowed.
2. Are there ways to make bolts unnecessary? Think about it!
3. Can we mine a greater thickness to help justify the cost of bolting? Say 50 ft. high instead of 25 ft. to halve the cost per ton…
4. Choose the system from mechanical anchorage or grouted rebars, to suit local conditions—hard rock or soft rock, wet or dry etc.
5. Determine where anchorage should be to form a stable structure. That will determine the length of the bolts.
6. Figure out a suitable spacing, usually to prevent falls from between bolts and plates. Add straps or mesh if necessary.
7. Figure the load per bolt, from number of cubic feet of rock to be suspended from the anchorage, at about 12-1/2 cu. ft. per ton.
8. Select the bolt strength to suspend that load. Civil engineers are likely to work with the yield strength of the bolt; miners are more likely to work with the ultimate strength, knowing that bolts are usually 10 to 15 percent stronger than the manufacturer specifies.
9. Test the system selected, in a small, out-of-the-way place if possible. Refine if necessary. And never stop thinking. Until we get that anti-gravity paint on the market we’ll always be looking for better ways to control the roof.
To close on a Scriptural note, we have an appropriate selection from
John 21, v. 3:
Simon Peter saith unto them “I go a-fishing.”
Everybody has to believe in something; I believe I’ll go fishing
too. And if perchance we meet at The Gates, we’ll have a lot of stories
to tell. Peter will make allowances for fish stories, which are, by definition,
not lies.
Jack Parker is the owner of Jack Parker and Associates. In reality, Parker has downsized, and the “Associates” are Jack’s wife, Levinia, and her small dog, Dulcie.
Fox River Implements Metso Turnkey Operation
Rock from Fox Riveršs
new crusher (center of photo) is conveyed
to an 8-by-20 finishing screen and then deposited to be picked
up by a wheel loader.
About 2.0 million
tons of rock are now available to Fox River Stone
customers annually, an increase of 36 percent over last year.
Located 40 miles west of Chicago in the Fox River Valley, Fox River Stone
Company was at its capacity to provide aggregates to its customers due
to the increase in new-housing and road construction in the area.
The quarry had adequate reserves, but needed to increase capacity and
lower operating costs. Consequently, in the spring of 1999, Rein, Schultz
& Dahl, Fox River Stone’s parent company, decided to invest in
a state-of-the-art aggregates processing facility.
The company developed design criteria and sent out bid packages. The packages
asked for bids for a plant that would provide a 50-percent increase in
rock produced per hour and rock that would meet Illinois DOT specifications.
The call for bids asked for a turnkey delivery that included everything
from planning the production flow to installing the crushing plants.
When Metso Minerals received the request for bid from Fox River Stone,
Jack Lange, its manager of systems application and design, and his team
of 11 people developed a plan.
The Metso Minerals team created a computerized flow chart of the plant
and determined the optimum production capability for each required product.
The plant was then analyzed to ensure complete flexibility for producing
new products, re-screening of products and operating at reduced production
during maintenance periods.
The previous machinery produced 500 tph; the new Nordberg primary crusher
produces 750 tons per hour with a maximum capability of producing 850
tons per hour, according to the company. Three 50-ton trucks make about
21 trips per hour between the quarry and crusher.
Yearly production capacity will increase and provide customers the opportunity
to purchase up to 2.0 million tons a year, which is a 36-percent increase
over previous years.
Construction on the new plants began in November 1999, while the quarry
was still in operation. All footings were poured and support materials
were put into place before the plant was shut down to install the new
crushers and update the conveyors.
Metso Minerals provided an onsite project manager during the construction
of the plants, and even though all of the mechanical and automated systems
were tested at the company’s Milwaukee facility prior to installation,
Metso Minerals sent technicians to the quarry on a regular basis to ensure
everything was working properly.
An important part of the project was the development of a computerized
operating system tied together with a fiber-optic cable, allowing the
primary plant to be controlled by the secondary-plant operator. Metso
Minerals worked with Fox River Stone and an integrator to install a system
that became the eyes for the plant operator.
The primary crusher has two television cameras that are monitored by the
plant operator in a control tower at the secondary crushing plant. Previously,
the primary crusher had an operator in a control room watching the plant
100 percent of the time.
In addition to monitoring the equipment, the automated system tracks much
of the statistical data of the quarry. Reports can be produced showing
the number of hours the crushers have run, how much down-time has occurred,
tons of each product produced per day, total primary and secondary plant
tonnage per day and other statistical data that enables plant managers
to make effective plant-management decisions.
The automated system provides the operator with data, which he uses to
schedule repair work and preventive maintenance. Each crusher, screen
and the 4,000 ft. of conveyer belts are monitored by sensors that route
information through a programmable logic computer which is interfaced
with a desktop computer. This computer has custom-designed graphics that
show the operator the product flow through the primary and secondary plants.
The operator knows which pieces of equipment are running and their operating
condition.
The sensors allow the plant operator to know what is going on with the
machinery in real time. If a problem occurs somewhere in the system, the
computer shuts down the plant sequentially. This prevents a pile-up of
rock, unnecessary clean-up and serious damage to equipment.
Sensors also allow plant operators to pinpoint problems and eliminate
guess work. And, in the event the automated system goes down, there is
a backup manual system at the primary and secondary control towers.
Not only is the machinery more productive, but the automated system also
allows employees to concentrate on the little things, like clean-up, lubrication
and preventive-maintenance checks that make the quarry run smoothly. Mike
Lacke, vice president of operations for Rein, Schultz & Dahl, said
no employees were let go as a result of all this automation.
“We’re going to be able to increase production by 36 percent
over last year and keep the plant’s manpower at the same level,”
he said. “We now have a computer system that does the mundane duties,
allowing employees to be more productive with their time.
“Our employees have worked hard to learn how to operate and maintain
the new plant, which has contributed to the success of this project,”
said Lacke.
During construction and onsite testing, and after the plant was up and
running, Metso Minerals personnel were onsite to ensure the plant was
running smoothly and construction was on schedule.
Fox River Stone employees also attended training sessions at Metso Minerals
to learn about the equipment and received hands-on training on maintaining
and repairing the plants. They also were trained in the operation of the
automated systems. Fox River Stone was shut down for a month while the
machinery and automation systems were installed and final testing was
completed. It was operational by May 2000. During the down time, Fox River
Stone had stockpiled rock and worked with customers to continue to meet
their needs.
Also providing support for the start-up of the turnkey operation was Roland
Machinery of Bolingbrook, Ill., a Metso Minerals distributor. Lamont Cantrell,
general manager for the Chicago division of Roland Machinery, explained
that because Metso Minerals designed an entire system, a lot of testing
and tweaking occurred, “similar to a shake-down cruise on a ship.”
He said his company acts as a communication liaison between Metso Minerals
and the quarry.
Fox River Stone supplies crushed dolomite products to asphalt and concrete
companies. Fox River Stone is a state-certified quality control/quality
assurance (QC/QA) supplier for Illinois DOT projects and meets all Superpave
regulations for state and federally funded projects. Fox River Stone employs
14 people in its quarry operation. Because it is located in a growing
residential area in South Elgin, it is allowed to operate only 12 hours
a day and 10 hours on Saturday.
Fox River Stone is unique in its mining process. The quarry has a contractor
remove 68 ft. of soil and clay to expose a 38-ft. depth of mineable rock.
This equates to about 150,000 cu. yds. of overburden to be removed monthly,
which is used to reclaim mined-out areas. Land that has been mined and
filled is planted with native grasses and trees to complete the reclamation
process.
A buffer of trees and grasses surrounds Fox River Stone and a high-pressure,
dust-suppression system is installed on plant equipment. Water trucks
further reduce dust.
The turnkey operation by Metso Minerals is one of the few the company
has done in North America. “Metso Minerals has been doing turnkey
operations in Europe for almost 40 years,” said Lange.
Crushing equipment includes a Nordberg C3055 jaw primary crusher plant.
Six-in.-minus rock then travels to a secondary cone crusher, a Nordberg
HP300. It is screened, and if necessary, is processed through one of two
tertiary crushers, both Nordberg HP400 cone crushers.
The site of the secondary and tertiary crushers, along with the conveyor
belts, is 600 ft. long and 135 ft. wide. The primary crusher is located
approximately one-half mile from the secondary plant. The plant layout
was designed to most efficiently utilize the area the company has available
for processing.
the bottom line...
Rein, Shulz & Dahl’s Fox River Stone Company had installed an automated Metso Minerals turnkey system, and it expects yearly production capability to increase by 36 percent over previous years.
To submit a suggestion for a Success in the Field or for more information about this story, contact AggMan at (717) 337-0027, fax (717) 337-9337 or e-mail Bill@aggman.com.
Battery Battles
Editor’s Note: This monthly column is supplied exclusively
for AggMan by The Equipment Maintenance Council (EMC).
As soon as one puts the key in the ignition of a vehicle and it does not
start, the immediate reaction is “Battery problem!” But as Roland
Best from Best Battery in Baltimore, Md., reports, batteries today do
not cause many vehicle problems.
When
a vehicle fails to start, the usual suspect is not always to blame.
“The battery manufacturing process is typically very good,”
said Best. “Most batteries simply wear out over time. For fleet-wide
problems, a qualified electrical technician is sometimes needed to determine
the actual cause.”
And Best should know. His service manager, Harold Winterbottom, has been
with Best Battery for many years and has made literally hundreds of road
calls to solve problems for customers.
Take, for example, the case of one major airline who was experiencing
problems with their baggage loaders.
“It was the middle of winter and this airline called us frantically
because half of their baggage loaders would not start,” explained
Winterbottom. “The equipment spent a great deal of time idling on
the runway in harsh winter weather.”
Winterbottom took amp readings at idle and while revving the engine, and
it was determined that the battery was not getting enough current at idle.
After a period of time, the battery charge would simply run out. Upon
reviewing both the airline’s equipment and operating environment,
it was decided that a specially designed heavy-duty starter and alternator
package was needed to accommodate long idle times on the runway. Best
commented that this airline has not had any battery or starter-related
problems with baggage loaders to date.
A well-known bakery company was complaining about frequent problems with
dead batteries on delivery trucks. Upon investigation of the electrical
system, Winterbottom noticed that there was a constant drain on the battery
causing it to lose its charge. Warehouse workers frequently played the
delivery van’s radio while loading the trucks. The aftermarket radios
were wired to the ignition side, instead of the accessory side of the
switch, which created an 8-amp draw from the battery. A simple re-wiring
solved the bakery’s problem.
Best recommends reviewing persistent battery and starting problems with
a qualified electrical technician before making any conclusions about
defective equipment. And when batteries do fail (as they sometimes do),
Peggy Bykowsky, battery product manager for John Deere explains that they
typically fail for one of two reasons:
About 50 percent of batteries fail because of the natural internal corrosion
process that builds up after years of use. This corrosion causes the battery
to lose its chemical effectiveness, and therefore it can no longer hold
a charge. Incidentally, hot weather and high ambient temperatures are
linked to early battery failures. Batteries used in very hot climates
tend to have shorter useful lives than their counterparts in cooler climates.
The other 50 percent of batteries fail as a result of poor maintenance,
improper charging techniques or general abuse. To prolong battery life,
Bykowsky suggests the following:
- Check batteries in the spring and fall for leakage, state-of-charge,
loose or frayed wires;
- Make sure terminal connections are tight and free from corrosion to
increase starting capability;
- Use the proper battery type for the application;
- Check fluid levels twice a year and do not overfill batteries to avoid
leakage that can result in damage to the battery;
- Keep battery holddowns tight to reduce vibration that can damage cases
and plates; and
- Disconnect the battery ground cable if the equipment will not be used for 60 days or longer. This will help reduce power drainage and prolong battery life.
Roland Best is president of Best Battery. He can be reached for comments or questions at (410) 342-8060. Peggy Bykowski is battery product manager for John Deere. She can be reached for comments or questions at (309) 765-4372.
The Equipment Maintenance
Council (EMC) is an individual membership organization comprised of equipment
maintenance professionals. Its members are responsible for the purchase,
maintenance, employee training, shop facilities and parts management of
leading corporations and government entities that utilize heavy, off-road
equipment. Its members also represent the major manufacturers and suppliers
of the heavy equipment industry. EMC provides end users with cutting-edge
education, and it is the only organization to offer a certification program
for the industry, the Certified Equipment Manager (CEM). For more information,
contact Stan Orr, CAE, EMC executive director,
at (970) 384-0510, e-mail at ceo@equipment.org,
or visit EMC’s web site at www.equipment.org.
Cold temperatures can be particularly detrimental to batteries that must be stored for the winter season. Gale Kimbrough from Interstate Battery System of America, Inc. in Dallas, Texas, recommends taking the following steps for long-term battery storage:
- Disconnect and remove the battery from the vehicle.
- Fully charge batteries to 100 percent before storing because they can deteriorate when allowed to remain discharged for extended periods of time. *Note: Always charge batteries according to charger instructions.
- Store battery in a cool, dry place and avoid areas where excessive heat or cold could affect the battery.
- Clean the battery case and terminals before storing. Clean with a neutralizing solution and dry thoroughly.
- Check and correct electrolyte levels before storage. The proper electrolyte
fill level is 1/8 in. below the vent well split ring.
It is best to use distilled or deionized water to fill the level as high as splash barrels (split ring) or as low as plate tops. - Do not stack batteries on top of one another.
- Test the battery’s state-of-charge every six to eight weeks with
a hydrometer or voltmeter to verify state-of-charge
is above 75 percent. - Always observe safety precautions when working on or near batteries.
Gale Kimbrough is technical services manager with Interstate Battery System of America, Inc. He can be reached for comment or questions at (800) 541-8419, ext. 6866.