Screening
Difficult Materials
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Compost - Sod - Top Soil with Weeds and
Grass |
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Weeds and grass pose no big problems as they will quickly be sorted out
and deposited in two piles.
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What to Watch For:
If the material is full of roots, some of the good dirt will go out
with the roots.
Simply run it through again to finish breaking up the root balls and
sortingout of good material.
Old fence rows, ditch banks etc. will yield great top soil to sell. |
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Log
Yard
Waste
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Very impressive but could be a
problem
These photos show (Photo 1) on the far right a pile of
log yard waste. It includes dirt, decayed wood and
larger pieces of wood. In the area near the loader is
the overs while at the center between the piles is
the screened (3/4”) dirt and decayed wood. |
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Photo
2
shows a close up of the overs which screened out very easily.
Trouble can arise, however if the longer pieces of wood are much
longer. What you see here is about maximum length before trouble may
start.
If a longer stick stands up and then lodges between the feeder conveyor
and the screen dish, it may poke a hole through the screen.
Obviously, a light wire, small hole screen is more vulnerable than a
larger opening, heavy wire screen.
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Screening
Sand
and Rocks |
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Screen wear and/or damage is effected by the shape of the rocks,
concrete or asphalt. Round rocks are much easier on the screen
then rocks with sharp corners. Therefore, be informed that heavier
screen wire is required for sharper shaped rocks, concrete or
asphalt.
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Rock Effect On Conveyors
Small rocks, 1/2” through 2” getting into the chain link and jamming at
the sprocket is remedied with rock guards on the single chain
conveyors. Belts or double chain conveyors are not subject to jamming
with small rocks.
Sand Problems
Single or double chain conveyors are not recommended for sand as
accelerated wear may
occur. To minimize problems with the overs conveyor, do not screen sand
with less than a 1/2” screen and do not over feed causing sand to be
discharged into the overs conveyor. A belt fines conveyor is best
for sand and should always be recommended. |
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Summary
In general, the chain conveyors will address the widest range of
operating conditions. The available conveyor
options may be selected to improve operating results for specific
applications.
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Trash
and
Long Stringy Roots |
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Shows material that should be removed prior
to loading in the hopper. The long pipe is sure to
cause the screen to stop
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Shows the type of material being screened out. The pile on the right
was successfully carried up the overs conveyor. The small pile close to
the machine was long, flexible roots that coiled up into a ball and had
to be pulled out by hand.
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Basswood
Bark |
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Ground wood such as materials ground in a hammer mill may have long
wood fibers with the
small particles mixed in.
These materials are hard to separate, even if you try to shake the
fines out by shaking a hand full. |
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Note the long stringy and frizzy strands of material.
While screening is possible, it takes attention to detail.
In this case, new material must be fed into the screen at the very top
(11:00) position.
If the customer has a way to feed at the top, such as a
grinder discharge conveyor, it may be worth a try.
Do not expect big production volumes |
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About
a
Grizzly
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You will hear folks talking about a “Grizzly”, so here are photos of
one.
It is simply spaced bars welded to a frame which material is dropped on
from a loader bucket. The big rocks will not pass through the bars and
small particles mixed in will. |
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The smaller particles do pass through and can be
retrieved from the rear. |
