Page 438 - Solid Waste Analysis and Minimization a Systems Approach

416 PRIMARY AND FABRICATED METAL INDUSTRIES

The industry includes manufacturers and processors of steel, iron, aluminum, copper,
and specialty metals like titanium, molybdenum, and beryllium. Steel products
account for about 50 percent of the market. Companies are involved in three major
types of activities. Primary processing is the separation of metal from ores in a furnace
to produce slabs or ingots of metal. Secondary processing involves mainly the rolling
or drawing of metal slabs into sheets, plates, foil, bars, and wire. Foundry operations
produce metal shapes by pouring molten metal into casts or molds. Some producers
have fully integrated operations, from mining raw materials to manufacturing finished
products, but most operate in just one type of activity.
Steel production first involves converting iron ore or scrap iron into molten steel.
The ore-based process uses a blast or oxygen furnace in a blast mill, and the scrap-
based process uses an electric arc furnace in a minimill. Next, molten steel is poured
and solidified in a continuous caster to produce semifinished products, like steel slabs,
billets, and blooms. These materials are put through a mechanical and heat-treatment
process known as hot rolling, and some hot-rolled sheets are rolled again at lower tem-
peratures (cold rolling) to form finished flat products such as plates, coils, or sheets,
or long products such as wire, bars, rails, or beams. These products may then be coated
with protective anticorrosion material.
The production of aluminum, copper, and other metals is similar. Metal is separated
from an ore by melting it. Metal alloys are produced by adding various elements to the
main metal. For example, 17 percent chrome and 8 percent nickel are added to iron to
create stainless steel. The different properties and characteristics of metal are pro-
duced by altering the chemical composition and the different stages of the process,
such as rolling, finishing, and heat treatment.
Primary production of metals requires large amounts of ore and large amounts of
energy, so producers often locate near ore deposits (copper companies); coal fields; or
sources of cheap electricity (aluminum companies). To ensure a supply of raw materials,
many primary producers control their own ore deposits. Transporting the finished prod-
uct is typically by rail. Producers can make thousands of different products because
metals can be made in many different grades of hardness or other properties. A producer
of castings and forgings, such as Citation, sells 20,000 products to 2000 customers.
The technology of making metals with desired physical and chemical properties is
highly complex. Modern production technology allows better control of the process
and is more energy-efficient, but is also expensive to install. Many modern plants are
highly automated, partly to reduce the need for expensive labor. Computerized inven-
tory systems are used to track thousands of products at multiple locations.
Industries in the primary metal manufacturing subsector smelt and/or refine ferrous
and nonferrous metals from ore, pig, or scrap, using electrometallurgical and other
metallurgical process techniques. Establishments in this subsector also manufacture
metal alloys and superalloys by introducing other chemical elements to pure metals.
The output of smelting and refining, usually in ingot form, is used in rolling, drawing,
and extruding operations to make sheet, strip, bar, rod, or wire, and in molten form to
make castings and other basic metal products.
Primary manufacturing of ferrous and nonferrous metals begins with ore or concen-
trate as the primary input. Establishments manufacturing primary metals from ore and/or