Copper in the USA: Bright Future – Glorious Past

Copper was first used by man over 10,000 years ago. A copper pendant discovered in what is now northern Iraq has been dated about 8700 B.C. For nearly five millennia copper was the only metal known to man, and thus had all the metal applications.

Early copper artifacts, first decorative, then utilitarian, were undoubtedly hammered out from "native copper," pure copper found in conjunction with copper-bearing ores in a few places around the world. By 5000 BC, the dawn of metallurgy had arrived, as evidence exists of the smelting of simple copper oxide ores such as malachite and azurite.

Not until about 4000 BC did gold appear on the scene as man's second metal. By 3000 B.C., silver and lead were being used and the alloying of copper had begun, first with arsenic and then with tin. For many centuries, bronze reigned supreme, being used for plows, tools of all kinds, weapons, armor, and decorative objects. Though copper came from the island of Cyprus-from whence its name-and numerous other sites in the Middle East, the origin of the tin in the bronze is still a mystery.

The Bronze Age suddenly ended at about 1200 BC, with the general collapse of the ancient world and the interruption of international trade routes. The supply of tin in particular dried up and the Iron Age was ushered in, not because iron was a superior material, but because it was widely available. The deliberate alloying of iron with carbon to form the first steels did not occur for centuries.

Economy in the use of copper and its alloys was necessitated by these early trade interruptions, and this efficiency in use and re-use has continued from that day to this.

US History

The large-scale mining of copper had its origins in the late 1800's, primarily in the American West. Small mines existed around the country, particularly in the Upper Peninsula of Michigan and in Arizona, but they were able to extract copper only from high-grade ores. The development of efficient flotation processes ¹ around the turn of the century opened up the exploitation in Arizona, Montana, and Utah of large porphyry ore deposits in which the copper-bearing minerals are widely dispersed throughout the host rock. Open-pit mining techniques were developed for these low-grade porphyry deposits and the United States quickly became the world's largest producer of copper.

The US brass mill industry has a longer history, beginning in the early days of the Republic. The industry was heavily concentrated in the Naugatuck Valley in Connecticut over a 40 mile stretch from Torrington through the center of the industry-Waterbury-south to Ansonia and Derby. The early mills made such objects as brass buttons and copper vessels, and later pins and clock brass, and developed melting and rolling techniques. Only since World War II has the brass mill industry been dispersed widely throughout the eastern half of the United States, and little of it remains in Connecticut.

The electrical wire mill industry started in 1877, when a Connecticut brass mill man named Thomas Doolittle developed hard-drawn copper wire strong enough to be strung overhead. Prior to that time, iron wire had been used in the telegraph system. The telephone system was commercialized quickly after its discovery in 1876 and both it and the growing electric power grid began to consume large quantities of copper wire. While these events were transpiring in the USA, similar developments in copper production and in the consumption of copper mill and foundry products were occurring also in the rest of the industrialized world. Annual growth rates over these periods have ranged from a high of 5.8% at the dawning of the electrical and telecommunication ages (late 1800's-early 1900's) to a low level of 1.3% in the period since the mid 1970's. Over this time period, annual world consumption has grown by about a factor of 30. In fact, despite copper's 10,000-year history of continuous use (and re-use), about three-quarters of all copper ever consumed has been produced in the period since World War II.

Production of Copper

The copper industry in the United States has two main segments: producers-mining, smelting, refining companies; and fabricators-wire mills, brass mills, foundries, powder plants. The end products of the producers, the most important of which are refined cathode copper and wire rod, are sold almost entirely to the copper fabricators. The end products of the fabricators-copper and copper alloy mill and foundry products-consist of electrical wire, strip, sheet, plate, rod, bar, mechanical wire, tube, forgings, extrusions, castings, and powder. These products are sold to a wide variety of users: chiefly the construction industry, manufacturing industries, and the government. Certain mill products, chiefly wire, cable, and most tubular products, are used without further metalworking. On the other hand, most flat-rolled products, rod, bar, mechanical wire, forgings, castings and powder go through multiple forming, machining, finishing, and assembling operations before emerging as finished products.

Copper Producers

At the beginning of copper's flow through the economy are the mining companies, which process vast quantities of low-grade ore, mostly from open-pit mines in order to produce copper. Approximately two tons of overburden must be removed along with each ton of copper ore. The ratio of overburden to ore is sometimes as high as 5 to 1. The ore itself averages less than 0.7% copper in US mines.

Copper ore normally is crushed, ground, and concentrated, usually by flotation, to produce a beneficiated ore containing about 25% copper. The ore concentrates are reduced to the metallic state, most often by a pyrometallurgical process. Traditionally, the concentrated ore is processed in a primary smelting reactor, such as a reverberatory furnace ², to produce a copper sulfide-iron sulfide matte, up to 60 percent copper. Today reverberatory technology is rapidly being replaced by oxygen/flash smelting, which greatly reduces the volume of off-gases. Sulfuric acid is manufactured from the sulfur dioxide contained in these off-gases, reducing air pollution by 95% or more and providing an important co-product of copper smelting. The matte is oxidized in a converter to convert the iron sulfides to iron oxides, which separate out in a slag, and to reduce the copper sulfide to blister copper, which contains at least 98.5 percent copper. Current technology combines the converting step with the preceding smelting step. Fire refining of blister copper then removes most of the oxygen and other impurities, leaving a product at least 99.5 percent pure, which is cast into anodes. Finally, most anode copper is electrolytically refined ³, usually to a purity of at least 99.95 percent.

The resulting cathodes are the normal end product of the producer companies and are a common item of commerce. In recent years, many producers have installed continuous-cast rod mills to directly convert cathode copper to wire rod (typically 5/16 inch in diameter), the feed material for the wire and cable mills. Primary producers may also convert the cathode to cakes or billets of copper for sale to brass mills. The consumption of refined copper (mostly cathodes) in the United States was about 2.5 million short tons (2.3 million metric tons) in 1989, about 27% of the total free world usage of 9.2 million short tons (8.3 million metric tons).

Hydrometallurgical processing is an increasingly important alternative to pyrometallurgy, particularly for nonsulfide ores, such as oxides, silicates, and carbonates. Weak acid is percolated through ore or waste dumps of rejected materials. Copper is leached out of the ore by the acid solution extraction, to produce an electrolyte suitable for electrowinning, wherein copper is extracted electrolytically much as anode copper is electrorefined. Electro-won copper is equal in quality to that produced by electrolytic refining.

In recent years well over half the copper consumed in the United States has been derived from recycled scrap, and this percentage has grown somewhat over the last two decades. About 55% of this scrap in recent years has been "new" scrap, such as turnings from screw-machined rod, and 45% has been "old" scrap, such as used electrical cable or auto radiators. Scrap recycled within a particular plant or company-runaround scrap-is not included in these statistics. About one-third of the scrap recycled in the United States is fed into the smelting or refining stream and quickly loses its identity. The remainder is consumed directly by brass mills; by ingot makers, whose main function is to process scrap into alloy ingot for use by foundries; by foundries themselves; by powder plants; and by others such as the chemical, aluminum, and steel industries.

Copper Fabricators

The four classes of copper fabricators together account for about 97% of the total copper (including alloying metal) consumed each year in the United States. Other industries, such as steel, aluminum, and chemical, consume the remaining 3%.
The wire rod mills' share of metal consumed has grown sharply over the last 20 years, to about 49% today, while brass mills have dropped to 40%. Foundries account for about 7% of fabricated products, and powder plants use only about 1% of the US supply of copper.

Copper wire mill products are destined for use as electrical conductors. Starting with wire rod, these mills cold draw the wire (with necessary anneals) to final dimensions through a series of dies. The individual wires may be stranded and normally are insulated before being gathered into cable assemblies.

Brass mills melt and alloy feedstock to make strip, sheet, plate, tube, rod, bar, mechanical wire, forgings, and extrusions. Somewhat less than half the copper input is refined and the rest is scrap. Fabricating processes, such as hot rolling, cold rolling, extrusion, and drawing are employed to convert the melted and cast feedstock into mill products.

About 45% of the output of US brass mills is unalloyed copper and high-copper alloys, chiefly in such forms as plumbing and air conditioning tube, busbar and other heavy-gage, flat products for electrical use, strip for auto radiator and other heat-exchanger fins, and roofing sheet. Copper alloys comprise the remaining 55%. Free-cutting brass rod, which exhibits outstanding machinability and good corrosion resistance, and brass strip, which has high strength, corrosion resistance, excellent formability, and good electrical properties, together constitute about 80% of the total tonnage of copper alloys shipped from US brass mills. Other alloy types of major commercial significance include copper-nickels, which are strong and particularly resistant to seawater and used for coinage; tin bronzes (phosphor bronzes), which are noted for their excellent cold forming behavior and strength; tin brasses, known for outstanding corrosion resistance; nickel silvers, which combine a silvery appearance with good formability and corrosion resistance; beryllium coppers, which provide outstanding strength when hardened; and aluminum bronzes, which have high strength along with good resistance to oxidation, chemical attack, and mechanical abrasion.

Foundries use pre-alloyed ingot, scrap, and virgin metal as raw materials. Their chief products are shaped castings for many different industrial and consumer goods, the most important of which are plumbing products and industrial valves. Centrifugal and continuous cast copper alloy products find major application as bearings, cylinders, and other symmetrical components.

Powder plants produce powder and flake for further fabrication into powder metallurgy parts, chiefly small sintered 4 bronze bushings, and other uses.

Industry Structure

The structure of the US copper and copper alloy industry has undergone dramatic changes over the last ten or twenty years. In 1966, for example, the United States was by far the largest producer of newly mined copper, as well as the largest consumer. In addition, US companies accounted for most of the output of the copper mines in South America, chiefly Chile and Peru, thus representing effective US control of about 45% of free world production.

The US-owned mines in Chile began to be nationalized in the late 1960s, and the government of Chile has greatly expanded their output. Today the US share of world mine production is about 18%. Chile has over a 23% share, nearly all of which is exported, and has the largest copper reserves in the world. Other important producers are, in order of mine production, Russia, Canada, China, Australia, and Zambia.

US Companies

were purchased by oil companies in the 1970s. A string of unprofitable years in the early 1980s led the oil companies (except one) to divest their copper subsidiaries. This, along with expanding international competition, led management of the again independent copper producers to bring new hydrometallurgy technology on stream, institute other production efficiencies and tighten other cost controls in a revitalization program that was perhaps unprecedented in US industry.

Today the US copper companies, despite the high cost of the world's strictest environmental standards, are well positioned to live with low price levels and to profit from improvements in the demand for copper.

Restructuring of the US brass mill industry in the past few years has been at east as profound. The same economic factors at work in recent years in the mining industry squeezed the profit margins of brass mills, which had been dominated by large full-line mills producing a wide range of products including strip, sheet, plate, rod, bar, forgings, mechanical wire, and tubing. Today there is only one full-line mill as compared to eight in 1970.

What has emerged are largely single-product operations, most with up-to-date production equipment, able to complete on a worldwide scale. Many older mills have been closed and other companies restructured through leveraged buyouts and employee stock ownership plans.

The wire and cable mills have seen some restructuring, particularly in the breakup of some of the large, multi-product operations with former equity ties to mining companies, and also through numerous mergers and buyouts. Overall, however, these changes have not been so profound as in the case of the copper companies and brass mills.

In contrast to other metal industries there exists today almost no top-to-bottom integration of the US copper industry. The only move toward integration in the last 20 years has been the addition of continuous cast wire rod mills to the end of the production process by several refining companies.

Markets

Despite popular belief that copper is a material that is always on the defensive and being substituted for, analysis shows the opposite to have been true over the last ten or fifteen years. In the late 1960's and early 1970's, copper was indeed the object of considerable substitution, particularly by aluminum in wire mill products. This aluminum penetration resulted in copper reaching its lowest market share at 71.9% of the total insulated wire and cable market in 1974, with particularly sharp aluminum inroads into power cable, building wire, and magnet wire (used to wind motors and transformers).

At about that time, safety problems, well publicized by the US Consumer Product Safety Commission, began to occur at connections in aluminum branch-circuit wiring used in well over a million homes up to that time. These problems were undoubtedly responsible for a sudden return to copper in building wire and some spillover effect into other wire and cable categories. Only in power cable, primarily overhead utility cable installed by highly trained professionals, has aluminum increased its market share since the mid-1970's. Today copper's share of the US insulated wire and cable market is about 78%.

Building wiring and plumbing have been the two top markets in recent years. Both have benefited from an increasing intensity of use (more electrical loads and more bathrooms in new homes). Plastics are an ongoing threat to copper in plumbing applications but their usage is still held back by their susceptibility to permeation by gasoline and other organics and to mechanical damage. They also do not exhibit copper's bacteriostatic properties.

Automotive applications, copper's third largest market, is the source of the most serious current substitution threat-aluminum in the radiator. Copper's answer to this threat is new soldering materials, better radiator designs, and new automated production techniques. Though aluminum has made inroads into the radiator, copper has gained far more due to the dramatic increase in wiring and electronics within the average car. Today, the use of copper and copper alloys in an average US-built passenger car is about 50 pounds, versus 36 pounds in 1980.

Telecommunications, on the other hand, has dropped from the number 2 spot to number 4 in less than a decade. Fiber optics is the popular explanation for this dip, but in fact it accounted for little of it prior to 1990. Other technological factors are responsible, such as subscriber carrier (piggybacking of many phone conversations on a single pair of copper wires) and the use of wires of smaller cross-section. This is a textbook example of copper applications being engineered for ever-increasing efficiency of use, which results in decreased poundage. Optical fibers are indeed a real threat for the future, however. Whether that threat is realized may depend more on cost factors than technical considerations.

Copper also goes head-to-head with aluminum in power utilities. Aluminum's light weight is its one advantage in current-carrying applications and it is used almost exclusively in overhead transmission and distribution cable. The advent of high temperature superconductors, today's hottest technical area, opens new vistas of possibility. Superconductors need to be surrounded by "shunt" materials, which can carry heavy currents around faults that occasionally occur in the superconductor. The mini-materials battle between copper and aluminum for the best such material for current-technology superconductors such as niobium-titanium has been won by copper. Superconductivity could be an important new market for copper, particularly in transmission lines, energy storage devices, and other applications not yet contemplated.

One negative of note for copper consumption is a large loss in copper's use in coinage. This occurred with a stroke of the pen in 1982, when a copper alloy was replaced by zinc in the penny. Roughly three-quarters of all US coins minted are pennies. A move is now afoot to create a new copper-base dollar coin, of more logical design than the ill-fated Susan B. Anthony coin, to eventually replace the dollar bill. Today's dollar is worth what a quarter was in the early 1960's, and Australia, Britain, Canada and many other countries have replaced their smallest denomination bills with coins.

A fact that is surprising to many is that when the markets are put on a usage-intensity basis-that is, pounds of copper used per unit of measure of each industry (use per housing start, per vehicle, per ton of air-conditioner capacity, etc.) -copper has shown increasing use in the last ten years. This is in contrast to the oft-quoted statement that the intensity of use of copper and other "mature" metals is falling rapidly.

The Future

Copper's healthy maintenance of markets and its promise to gain new ones, such as superconductivity applications, new marine uses such as ship hulls and sheathing of offshore platforms, electric vehicles, earth-coupled heat pumps, solar energy (which will inevitably re-emerge at some point when oil supplies tighten), fire sprinkler systems, and nuclear waste disposal canisters, to name a few, must be balanced against its prospects of future availability.

Of the world's reserves of copper about one-quarter of the deposits are economically recoverable now or in the near future. Of this reserve base about 16% (198 billion pounds of copper) is in the USA.

Each year about 3 billion pounds are withdrawn from the earth as US mine production, a barely discernible amount. The copper already mined through history amounts to 700 billion pounds, most still in recycling use.

Interestingly enough, although copper is continuously mined and put into use, the estimated US reserve base has stayed relatively constant in recent years, and has increased fourfold from estimates made in 1952 as new deposits have been found and, even more important, because better extraction techniques have allowed leaner deposits to be added to the reserve base. There is every reason to believe that these dynamics will continue well into the 21st century.

Three other factors will also influence copper supply: US self-sufficiency, energy efficiency and recyclability.

The availability of major domestic deposits makes the USA self-sufficient in copper. This is in stark contrast to aluminum which, despite recent advances in domestic supply due to recycling of beverage cans, has only averaged 20% US self-sufficiency.

There are wide variations in the energy used to recover metals from the earth's crust. Copper ranks near the middle for energy required for extraction-higher than iron, zinc or lead, but at considerable advantage to aluminum, titanium and magnesium, which require much larger quantities of energy to break down the ore (or seawater and brines in the case of magnesium) into metallic form.

For all metals the recycling of scrap is considerably more energy-efficient than recovery from ores, and here copper's high recycling rate-higher than any other engineering metal-makes it the material of choice.

Each year in the USA more copper is recovered and put back into service from recycled material than is derived from newly mined ore. Copper's recycle value is so great that premium-grade scrap normally has at least 95% of the value of primary metal from newly mined ore.

The inescapable conclusion is that copper will continue its 10,000-year history of usefulness many millennia into the future.

Term Definitions

Flotation Process - The process of separating different minerals by agitating a pulverized mixture of the materials with water, oil, and chemicals. Differential wetting of the suspended particles causes unwetted particles to be carried by air bubbles to the surface for collection.
Reverberatory Furnace - A furnace or kiln in which the material under treatment is heated indirectly by means of a flame deflected downward from the roof.
Electrolytically Refining - A hexademical change produced by running an electric current through a mineral when molten to produce an electrically conductive medium.
Sinter - To cause (metallic powder, for example) to form a coherent mass by heating without melting.

The information provided in this section has been collected from many varied sources and is true and accurate insofar as the Copper Development Association Inc. has been able to determine.