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| Feed
Mill Issues – Flow Properties and Inventory Control |
Micronutrients TBCC®
(TBCC) is an improved source of copper for animal feeds. Compared
to copper sulfate, TBCC is more concentrated, flows better
and is less irritating to workers handling the product. However,
operating personnel need to be aware of its different properties
to take full advantage of the available savings.
Copper sulfate is hygroscopic – it draws moisture out of the
air – and therefore its assay actually changes depending on
relative humidity. This same property causes it to recrystallize.
The result can be small lumps removed by the feed mill’s cleaner
screen (under-dosing copper), larger lumps that clog the micro
bin auger (downtime and worker exposure), or, in the worst
case, wasted time for return of a shipment of hardened material.
Because copper sulfate is an acid, it is very irritating to
skin, eyes and mucous membranes. Workers unclogging a micro
bin or auger can get nauseated from exposure to the dust.
By contrast, TBCC is a neutral compound and thus inherently
less irritating in the case of accidental contact. Since it
is non-hygroscopic, there is little probability of needing
to unclog equipment.
Flow Properties
Users report that TBCC "flows like water". This obvious improvement
over copper sulfate is caused by two factors:
Due to acidity and hygroscopicity, copper sulfate crystals
tend to have a "sticky" surface. TBCC particles have a smoother,
more spherical shape, are smaller and have a much tighter
size distribution. By comparison to the sulfate salt, they
behave more like marbles.
Inventory
Management
After switching to TBCC some mills have experienced problems
reconciling consumption against inventory measurements. In
each case, these problems have been eliminated by fairly simple
adjustments in procedures and/or equipment. Compared to copper
sulfate, TBCC’s copper concentration is higher by a factor
of 2.3 and its bulk density by 1.3 (these factors are multiplicative).
Any measurement errors or losses have a correspondingly bigger
material management impact. The following are some contributing
factors mentioned by various users.
- Micro
feeders need to be adjusted - not only to feed less
but also to shut off or reverse earlier. The flow-through
experienced with all products is more significant with
TBCC. The higher density, concentration and flow mean
that a given volume of run off and/or flow-through contains
3 times as much copper.
- A
lip should be welded across the bottom of the auger tube
- TBCC’s excellent flow properties can cause more volume
of flow-through. This effect is exaggerated if vibration
is present. This can be eliminated by welding a small
dam across the bottom half of the outlet end of the auger
tube.
- Inventory
measurements should be taken at consistent levels
- Measurement of inventory in the micro bin is typically
done by measuring down from the top. The volume calculations
need to be adjusted for the higher bulk density of TBCC
(110#/cu.ft.). In addition, since the sides of the bin
taper toward the auger, a volume vs. height chart needs
to be used that is specific for the bin in use. Since
any error here is about 3 times as significant with TBCC,
it is best to take the measurement each time with the
bin nearly full or nearly empty.
- Damaged
bags should be repaired immediately - Spillage losses
become more significant with TBCC. A loss of 20 pounds
of copper sulfate may be only 4% of a day’s consumption
in a large mill. With TBCC, the same 20 pounds would represent
more than 9% of daily consumption. Because it flows so
well, even a small hole can result in considerable loss
when a bag is moved around in the mill. Therefore any
bag punctures (i.e. for QC samples) or leaks should be
taped immediately.
Dust Issues
When TBCC was first introduced to the market, it had a significant
dust component – defined as particles less than 10 micron.
Particles larger than 10 micron do not float in the air or
behave electrostatically. Improvements in the manufacturing
process have steadily reduced this fraction.
The
level of dust in TBCC is currently lower than in most samples
of domestically-produced, feed-grade copper sulfate evaluated
in our laboratory, including three of the four in the earlier
graph on particle size distribution. Mills using TBCC report
that workers find it far more comfortable to handle than copper
sulfate.
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