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Lead: Battery Manufacturing eTool

Oxide and Grid Processing >> Oxide Conveyance and Classification


Toxic Material Belt Conveying Head Pulley
View larger image of toxic material belt
conveying head pulley
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 Conveyor
View larger image of toxic material
belt conveying head pulley


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.
    Arrow Conveyor Belt Ventilation
    Arrow 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 1. Drag link conveyor


Figure 2. Chain and flights (white discs) of a drag link conveyor
Figure 2. Chain and flights (white discs)
 of a drag link conveyor


Figure 3. Clear tube showing how the drag link conveyor works
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.
    Arrow Drag link Conveyor Configuration Diagram (Part 1)
    Arrow Drag link Conveyor Configuration (Part 2)
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Screw Conveyors
Figure 4. Enclosed screw conveyor
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.
    Arrow Screw Conveyor Components

  • Establish a preventive maintenance program for all lead handling processes and equipment.
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Classification
Figure 5. Cyclone classifiers
Figure 5. Cyclone classifiers
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
  • Leaking equipment.
Possible Engineering and Work Practice Controls
  • Provide a preventive maintenance program to maintain system integrity.
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