SIC 1446 Industrial Sand

Contenidos

• NAICS CODE(S).
• INDUSTRY SNAPSHOT.
• ORGANIZATION AND STRUCTURE.
• Glass Sand.
• Molding Sand.
• Fracturing Sand.
• Abrasive Sand.
• Other Uses.
• Producing Regions.
• BACKGROUND AND DEVELOPMENT.
• Mining Methods.
• Processing.
• Developments in the late 1990s.
• CURRENT CONDITIONS.
• INDUSTRY LEADERS.
• FURTHER READING.

SIC 1446

This category covers establishments primarily engaged in operating sand pits and dredges, and in washing, screening, and otherwise preparing sand for uses other than construction, such as glass making, molding, and abrasives.

NAICS CODE(S)

212322

Industrial Sand Mining

INDUSTRY SNAPSHOT

In 2003, 67 U.S. companies in 34 states produced an estimated 28.3 million metric tons of industrial sand and gravel with a total value of $566 million. Illinois, Michigan, California, North Carolina, Texas, Wisconsin, New Jersey, and Oklahoma accounted for 59 percent of the national industrial sand and gravel total that year. U.S. consumption of industrial sand and gravel grew from 26.1 million metric tons in 2002 to 27.2 million metric tons in 2003.

ORGANIZATION AND STRUCTURE

Glass Sand

The single most common use of industrial sand (38 percent of total tonnage in 2003) is in glass making, where glass or quartz sand constitutes 52 to 65 percent of the weight of finished glass. Glass sand requires a high percentage of silica—the principal ingredient of sand—because the presence of other elements such as iron oxide and clay introduces visible impurities that mar the glass's transparency. Few sandstones or natural sands (such as beach or dune sand) are pure enough to yield glass without "beneficiation," or the removal of impurities through processing. Glass sands are graded according to average grain size, which can be determined by passing them through sieves of varying calibers.

The container glass industry was one of the largest consumers of silica-based glass sand in the United States in the late 1990s, but the trend toward glass recycling, as well as increased plastic bottle and aluminum can packaging, weakened demand for silica sand. Some states require that 35 percent of container glass be comprised of recycled glass, with the potential for increases of as high as 65 percent recycled glass content by 2005. This trend was partly offset in the late 1990s, however, by heightened demand for flat glass, special-purpose glass, glass microwave packages, and glass containers for sparkling and flavored waters.

Molding Sand

Molding or foundry sand is traditionally the second most common use (20 percent in 2003) of industrial sand. Sand is used in these applications to make molds into which molten metal is poured in metal casting and as the "core" sand used in such molds to produce hollow areas in the final casted product. Sand needs to contain several properties to be used in foundry or molding applications. Internal cohesiveness and heat resistance—or refractoriness—enable the mold to withstand the high temperatures of the metal casting process (in steel applications, temperatures of 1340 to 1500 degrees Fahrenheit). Second, the sand's moisture content, and the type and amount of bonding agent (such as clay) within it, govern its ability to withstand the pressure exerted by the casted metal during heating. A third requirement is the sand's permeability, or its ability to allow water vapor and gases from the molten metal to escape during the casting process for cooling. Finally, the sand's composition and texture determine whether it will react chemically with the casted metal and whether it will create a smooth surface on the metal when it cooled.

While so-called naturally bonded molding sand contains enough clay and other bonding material to be used in metal casting without the addition of other bonding ingredients, synthetic molding sand consists of silica sand to which a specific amount (about 5 to 10 percent)...