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Certain material transporting operations call for mechanical conveyance. Common conveyance methods used in battery manufacturing facilities include:
Classification separates the oxide particles by size, allowing only particles within the desired size range to
the paste mixing operation.
| Pneumatic Conveyors |
Pneumatic conveying systems use air to transfer lead oxide from one point to another via pipes.
Potential Sources of
Exposure
- Leaking equipment.
- Damaged
bags in bin vent or
baghouse.
Possible Engineering and Work Practice
Controls
- Repair leaks and
replace bags immediately.
- Use self-adhesive neoprene gaskets at all joints to provide a dust-tight seal.
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| Belt
Conveyors |
Belt conveying
systems use belts to transport lead oxide
material.
Potential Source
of Exposure
- Lead dust may be emitted from open
conveyor systems:
- At the receiving end.
- At the discharge end.
- At the underside of conveyor.
- From spillage along the conveyor
belt.
Possible
Engineering and Work Practice Controls
- Provide an enclosed conveying system,
such as a screw or pneumatic conveyor,
in place of an open conveyor belt where
possible.
- Totally enclose and exhaust ventilate
the conveyor from loading to transfer
points.
Conveyor
Belt Ventilation
Toxic Material Belt Conveying Head Pulley
- Provide an exhaust ventilated
enclosure at the conveyor loading and
unloading points to minimize dust
emissions.
- Provide a trough belt and conveyor
skirting to minimize spillage.
- Provide a baffle to ensure the
unloading of conveyor at transfer point.
- Provide a belt scraper at the
discharge end to dislodge dust particles
that may adhere to the belt surface.
- Provide access doors to conveyor and
transfer point enclosures to facilitate
maintenance, wash down, and other
activities.
- Use top-hinging doors for inspection
to prevent spillage of leaded material.
- Provide drains and sumps in conveyor
trench to collect wash water and mud.
- Provide hose bibs for manually washing
the conveyor equipment.
- Wet down floors to suppress dust
generation.
- Note: If wet lead oxide gets into a storage tank, it could lead to an oxide fire. Do not use water in
areas with lead oxide silos or storage bins. Also keep water away from molten lead as explosions may
result.
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| Drag Link Conveyor |
Figure 1. Drag link conveyor
Figure 2. Chain and flights (white discs)
of a drag link conveyor
Figure 3. Clear tube showing how
the drag linkconveyor works
|
Tubular drag link conveying systems consist of disc-shaped flights attached to a chain inside a tubular housing. The chain
is driven by a motor connected to a drive sprocket. Hoppers located above holes in the housing, feed
material into the conveyor; holes cut in the bottom of the housing form the outlet.
Potential Source of
Exposure
- Lead dust may be emitted from open conveyor
systems at:
- The receiving end.
- The discharge end.
- Leaking flange connections.
Possible Engineering and Work Practice
Controls
- Provide
a preventive maintenance program to maintain system
integrity.
- Adjust the takeup (usually located near the drive sprocket) regularly to remove slack
in the chain caused by stretching.
- Inspect the chain and flights periodically for material buildup and wear.
- Replace chain and flight components through the inspection opening to avoid dismantling
the conveyor.
- Totally enclose and exhaust ventilate
the conveyor from loading to transfer
points.
Drag
link Conveyor Configuration Diagram (Part 1)
Drag
link Conveyor Configuration (Part 2)
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| Screw Conveyors |
Figure 4. Enclosed screw conveyor
|
Screw conveyors are sometimes used in the battery manufacturing industry to transport lead oxide to the paste mixing area
(Figure 4).
Potential Sources of
Exposure
- Lead dust may be emitted from leaking screw conveyors and at
discharge points.
Possible Engineering and Work Practice
Controls
- Enclose screw conveyor systems that transport leaded
materials.
- Dust Control Handbook: Screw Conveyors.
OSHA and the Bureau of Mines, U.S. Department of the Interior (1987, February), 20
pages. This handbook consolidates information developed by industry and government
laboratories on dust control engineering techniques for metal and nonmetal mineral
processing.
- Enclose and exhaust ventilate screw conveyor transfer
points.
- Dust Control Handbook: Transfer Chutes.
OSHA and the Bureau of Mines, U.S. Department of the Interior (1987, February), 20
pages. This handbook consolidates information developed by industry and government
laboratories on dust control engineering techniques for metal and nonmetal mineral
processing.
- Maintain cover gaskets and repair leaks
immediately.
Screw
Conveyor Components
- Establish
a preventive maintenance
program for all lead
handling processes and
equipment.
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| Classification |
Figure 5. Cyclone classifiers
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Air classification equipment (cones or cyclones) operate by applying opposing
air flows and centrifugal forces to the oxide material. By balancing the two forces, the heavier
particles spiral out and down where they are collected, and finer particles flow up to the top, where
they may be passed to another cyclone with finer classification capability. Through this process, the
desired particle size distribution is obtained.
Potential Sources of
Exposure
Possible Engineering and Work Practice
Controls
- Provide
a preventive maintenance program to maintain system
integrity.
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