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The Non-Ferrous Metals Industry:
Improvement of Resource Efficiency and Environmental Performance
There are many kinds of
non-ferrous metals. The most common, aluminum, lead, copper and zinc, are
specifically covered in the EPA Profile of the Nonferrous Metals Industry and in
several other reports. Many of the cleaner production possibilities described in
this report would apply to other metals as well. Once metal has been refined, it is
usually cast into ingots at the same factory, so the Profile
of the Metal Casting Industry is a complementary report to the two just described.
Forging is a related industry. See the Iron and Steel
page for related links.
Most cleaner production options in this industry and its subsectors involve installing
emissions control equipment that enables product recovery. There are relatively few
low cost options. Air emissions control is very important for refiners. Many
have modified their production processes by installing sulfur fixation equipment. This
equipment not only captures the sulfur before it enters the atmosphere, but processes it
so that a marketable sulfuric acid is produced. In primary aluminum refining, when a
pre-baked anode is used, the electrolytic cell, or pot, can be closed, thereby increasing
the efficiency of the collection of fluoride emissions. New carbon liners have been
developed which significantly increase the life of the aluminum reduction cell. This has
resulted in large reductions in the amount of spent potliner material generated by the
aluminum industry. Energy conservation and cleaner production are closely linked in
this industry. Researchers will find several good basic guides and a number of case
studies. The trade and professional associations are likely to be the best source
for detailed process-specific solutions.
The table below lists solutions to reduce waste and
pollution in non-ferrous metal production. Company environmental programs should
demonstrate that these options have been considered thoroughly. Direct links to online
guides to non-ferrous metals pollution prevention follow the table.
Solutions to Increase Efficiency and Reduce Waste in Non-Ferrous Metals
Production
| Control and recover gases |
Use doghouse enclosures where appropriate; use
hoods to collect fugitive emissions. |
| Produce new product from waste gases |
Mix strong acidic gases with weak ones to
facilitate production of sulfuric acid from sulfur oxides, thereby avoiding the release of
weak acidic gases. |
| Recover by-products |
Maximize the recovery of sulfur by operating
the furnaces to increase the SO2 content of the flue gas and by providing efficient sulfur
conversion. Use a double-contact, double-absorption process. |
| Neutralize acid wastes |
Desulfurize paste with caustic soda or soda
ash to reduce SO2 emissions. |
| Conserve energy |
Use energy-efficient measures such as waste
heat recovery from process gases to reduce fuel usage and associated emissions |
| Improve equipment |
Use low-NOx
burners. |
| Change |
Use suspension or fluidized bed roasters,
where appropriate, to achieve high SO2 concentrations when roasting zinc sulfides. |
| Recycle wastes |
Recover and reuse iron-bearing residues from
zinc production for use in the steel or construction industries. |
| Improve pollution control |
Give preference to fabric filters over wet
scrubbers or wet electrostatic precipitators (ESPs) for dust control. |
| Change fuel type |
Give preference to natural gas over heavy fuel
oil for use as fuel and to coke with lower sulfur content. |
last updated 02/25/06
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