Copper Industry

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COPPER INDUSTRY

COPPER INDUSTRY. Archaeological evidence found in pits on the Upper Peninsula of Michigan and on Isle Royal in Lake Superior reveals that copper mining and the making and use of copper implements and weapons in North America were carried on during a prehistoric

period extending from about 5,000 to 1,000 b.c. Vast copper mining pits remained that indicated extensive production. Copper production revived in the United States with the discovery of a vein of copper ore at Simsbury, Connecticut, in 1705. In 1709 copper production began from this ore, followed later by the discovery and development of other deposits in the colonies. English colonial law forbade smelting in the colonies, and so most of the ore was shipped to England. Small amounts of ore were smelted in the colonies, however, in spite of the prohibition.

It was not until exploitation of the rich ore deposits of the Upper Peninsula of Michigan in the early 1850s that copper production in the United States exceeded a few hundred tons per year. In 1842 the Chippewa Indians ceded all claims to thirty thousand square miles of the Upper Peninsula. In 1843 the copper rush began as thousands came to the peninsula to try their luck in the mines. The Keweenaw Peninsula, in Lake Superior, rapidly filled with copper mining boom towns, and several important harbors opened. Copper was shipped on Lake Superior to the St. Mary's River Canal at Sault Ste. Marie until the Soo Locks opened in 1855. The opening of the locks, combined with the advent of the railroad, increased both productivity and immigration to the area. In 1849, miners discovered massive deposits of copper buried deep in the earth at the Cliff Mine area near Eagle Harbor, Michigan. Unlike surface copper, which prehistoric glaciers had scattered across the country side, the Cliff Mine area boasted rich veins of ore. Rapid developments in copper mining technology produced equipment capable of hoisting massive amounts of metal from deep mine shafts.

Production of Michigan copper increased from 728 tons in 1850 to more than 30,000 tons in 1880. In the early 1850s the U.S. copper industry was dominated by the Calumet and Hecla Mining Company in Michigan, which was producing one-half of the domestic output from ore that ran as high as 20 percent copper. All the Michigan copper, known as Lake Copper, was marketed by Calumet and Hecla through a pooling agreement known as the Lake Pool. The preeminence of Michigan in copper mining was considered unassailable, particularly by those who financed the Lake development.

Despite Michigan's apparent monopoly, competition from the western states mounted. The first discovery of copper in Montana was at Butte in 1866 in the Parrot mine, which was then being mined for silver. The area became famous for copper production in the early 1880s from the output of the Anaconda mine. Later, the Anaconda Copper Mining Company gained control of most of the mining properties in the Butte area. During this same period, exploitation of the southwestern oxidized silver-copper deposits also began. In Arizona the operations of two mines, the Bisbee and the Copper Queen, merged in 1885, forming the basis for the great copper mining operations in Arizona. In the 1970s, the Arizona mines accounted for about one-half of the domestic production of primary copper.

In the 1860s the emerging electrical industry created a new demand for metals from which to make conductors. Copper proved to work best as an electrical conductor. The potential size of the electrical industry as a market was apparently not recognized, and the competition for a supposedly limited market between the western producers and the Lake Pool headed by Calumet and Hecla became critical. Prices were slashed, and by 1886 copper sold for ten cents per pound, compared with the average selling price of twenty cents per pound during the previous ten years. The price war scarcely checked western production, and the increasing production of Butte copper surpassed the Lake Pool total Michigan output by 1888. By 1900 the Michigan mines had reached maturity, and mining there became too expensive an endeavor. This shifted the focus of the copper industry to the West.

Advances in technology had considerable impact on the U.S. copper industry. Introduction of the Bessemer steel converter for smelting copper in the late 1880s made it possible to treat many lower-grade ores. The beginning of open-pit mining in 1907 permitted profitable exploitation of the huge bodies of low-grade disseminated copper sulfide ores in the Southwest. The flotation process introduced into the copper concentrators between 1913 and 1916 drove the tenor of profitable ore even lower. Since the standard blast furnace-converter process was not suitable for smelting the fine-grain flotation concentrate, the blast furnace was replaced by the open-hearth steel-making furnace to smelt roasted concentrates. Later, after the Phelps Dodge Company demonstrated that unroasted concentrates could be smelted, many companies eliminated the roasting step.

World War I provided tremendous impetus to the domestic copper industry. The United States became the copper clearinghouse for the Western Hemisphere and for the world. With increasing worldwide demand, South American and African deposits were developed and brought into production, largely with U.S. capital. World War II brought the copper industry to all-time high production records. Refining output soared to 1.5 million tons annually, and the United States firmly established dominance in copper production. Even so, the nation's needs outstripped domestic production, and by 1970, imports accounted for about 17 percent of the domestic supply.

Following World War II, hydrometallurgy grew as a commercial method of extracting copper in the United States. Dissolution and precipitation—collectively referred to as leaching—were used extensively for treating copper-bearing mine waste and for processing oxide ores. The copper precipitates produced by this method, which accounted for less than 5 percent of the total domestic copper produced in 1945, accounted for about 12 percent in 1970.

The processing of copper ores supplies a host of by products important to the economy, including lead, zinc, gold, silver, molybdenum, palladium, and platinum. Production of copper from the porphyry deposits in the western United States provides the only domestic source of the metal rhenium. Another important by-product is sulfuric acid, made from the stack gases at copper smelters. In 1970 about 600,000 tons of this acid were produced from this source. The production of acid and other sulfurous products, whether marketable or not, increased dramatically in the late twentieth century as smelter operators strived to meet new and stringent air-pollution regulations, which severely restricted the amount of sulfur dioxide that could be discharged into the atmosphere. Pollution abatement at smelters is costly and will force the industry to adopt new smelting technologies.

In 1974 U.S. consumption of refined copper was 2.3 million tons—of which 1.6 million tons were produced domestically—and an additional 0.8 million tons of copper were consumed as scrap in production of alloys, chemicals, and other products. By 1991 the United States produced almost 18 percent of the world copper production of some 8.8 million metric tons. By the early 2000s the largest copper ore producing states were Arizona, Utah, and New Mexico.

Because copper is so malleable and has high electrical conductivity properties, the largest use of copper is in electrical applications, which consume about one-half of the supply. Copper is extremely ductile and can be drawn into wires with diameters as small as .025 mm. It is widely used in outdoor power cables and in household wiring, as well as in signaling devices, electromagnets, and communications equipment. Copper wires are commonly used in the manufacture of electric motors, power generators, motor-generator sets, electrical controls, and related apparatuses, which require the use of copper for best performance.

BIBLIOGRAPHY

Finn, Janet L. Tracing the Veins: Of Copper, Culture, and Community from Butte to Chuquicamata. Berkeley: University of California Press, 1998.

Hildebrand, George Herbert, and Garth L. Mangum. Capital and Labor in American Copper, 1845–1990: Linkages between Product and Labor Markets. Cambridge, Mass.: Harvard University Press, 1992.

Hyde, Charles K. Copper for America. Tucson: University of Arizona Press, 1998.

Lankton, Larry D. Beyond the Boundaries: Life and Landscape at the Lake Superior Copper Mines, 1840–1875. New York: Oxford University Press, 1997.

Thurner, Arthur W. Strangers and Sojourners: A History of Michigan's Keweenaw Peninsula. Detroit, Mich.: Wayne State University Press, 1994.

James T.Dunham/h. s.