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.