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Refining and Casting > Refining
| Typically, metal from the smelting furnace is melted in an indirect-fired kettle or pot and the trace elements are combined to produce the desired alloy. Employees may be exposed to lead fume and particulate during the refining process. |
Click for larger view of refining kettle diagram |
| Refining |
Potential Sources of Exposure:
- Lead particulate may become airborne due to updrafts created by thermal rise from the surface of the refining kettle during preheating and cleaning.
- Lead fumes or particulate may be emitted from the surface of the molten lead
during
the
transfer
of
lead
to the
kettle
and
from the kettle during melting, adding refining agents, and stirring of molten alloy.
- Lead emissions may occur while drossing lead kettles.
- Settled dust may be reentrained due to vibrating equipment and vehicular traffic in the area.
Engineering and Work Practice Controls:
Fig. 1. Removing pump from enclosed refining kettle
Fig. 2. Ventilated lead launders to refining kettles |
- Provide exhaust ventilated enclosure for refining
kettles (Fig. 1).
 Refining Kettle Diagram
- Enclose
and
exhaust
ventilate
all
launders (Fig. 2).
Controls for Lead Tapping and Pouring
- Pump rather than pour molten lead when possible.
- Keep molten lead temperatures to a minimum to reduce lead fume generation.
- Provide local exhaust ventilation hoods and ductwork that does not interfere with the use of overhead cranes.
- Provide roll back access doors to allow the addition of refining agents.
- Provide a supplied air island near the refining kettle.
Supplied Air Island Diagram
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