(MERAF) for the Base Metals Smelting Sector - CCME

concentrations of heavy metals, and present a risk to the environment by the
gradual leaching of heavy metals from the residue material. Residues generated
during the leaching process are landfilled or stored in a secure site, are stabilized
to immobilize the metals, or are sent to another process for recovery of remaining
metals of value.
2.4.9. Electrowinning
As electrowinning takes place in tank houses open to the atmosphere, oxygen
gas or other gas generated during the electrowinning process can entrain the
acid or other solvent into the air.
2.4.10. Casting
Air emissions of particulate matter and metals arise from the transfer of molten
metal to the mold and from the cutting to length of the product with torches.
Wastewater effluents are generated during the cooling and cleaning of the hot
metal and can contain scale particles and oil. Wastewater is typically treated and
reused or recycled. Solid waste is generated from the cutting of the metal but is
minor in amount and is recycled within the plant.
2.4.11. Process Off-Gas Conditioning
Process off-gas conditioning generates collected dusts and sludges which are
either returned to production processes for recovery of metals or are disposed of.
The type of off-gas conditioning technology is also of environmental concern.
The use of wet ESPs and wet scrubbers results in the cross-media transfer of
pollutants in air to water.
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