Base Metals - Copper, Lead, Nickel, Zinc, and others
In chemistry, the term base metal is used informally to refer to a metal that oxidizes or corrodes relatively easily, and reacts variably with diluted hydrochloric acid (HCl) to form hydrogen. Examples include iron, nickel, lead and zinc. Copper is considered a base metal as it oxidizes relatively easily, although it does not react with HCl.
Base is used in the sense of low-born, common and inexpensive metal, in opposition to noble or precious metals like gold or silver. Coins once derived their value primarily from the precious metal content; however most modern currencies are fiat, allowing coins to now be made of base metal. In the context of plated metal products, the base metal underlies the plating metal, as copper underlies silver in Sheffield plate. A long-time goal of alchemists was the transmutation of base metal into precious metal.
In mining and economics, base metals refers to industrial non-ferrous metals excluding precious metals. These include copper, lead, nickel and zinc. The U.S. Customs and Border Protection is more inclusive in its definition. It includes, in addition to the four above: iron, steel, aluminium, tin, tungsten, molybdenum, tantalum, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium and thallium.
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High Grade Copper futures contracts are traded on the COMEX under ticker symbol HG and are delivered every month of the year.
Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; a freshly exposed surface is orange-red and acquires a reddish tarnish when exposed to air. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.
Copper has been in use at least 10,000 years. Alloying copper with tin to make bronze was first practiced about 4000 years after the discovery of copper smelting, and about 2000 years after "natural bronze" had come into general use. Brass, an alloy of copper and zinc, was known to the Greeks, but became more significant during the Roman Empire. In the Roman era, copper was principally mined on Cyprus, hence the origin of the name of the metal as cyprium (metal of Cyprus), later shortened to cuprum.
Copper compounds are commonly encountered as copper salts, which often impart blue or green colors to minerals such as turquoise and have been widely used historically as pigments. Architectural structures were built with copper corrode to give green verdigris (or patina). Together with osmium (bluish), and gold (yellow), copper is one of only three elemental metals with a natural color other than gray or silver. Decorative art prominently features copper, both by itself and as part of pigments.
Copper ions are water-soluble, where they function at low concentration as bacteriostatic substances, fungicides, and wood preservatives. In sufficient amounts, they are poisonous to higher organisms; at lower concentrations it is an essential trace nutrient to all higher plant and animal life. The main areas where copper is found in animals are the liver, muscle and bone.
The major applications of copper today are in electrical wires (60%), roofing and plumbing (20%) and industrial machinery (15%). Copper is mostly used as a metal, but when a higher hardness is required it is combined with other elements to make an alloy (5% of total use). Far East Asia and emerging economies like India and especially China are developing modern infrastructures, and are now having a greater influence on copper supply, demand and prices than western nations.
Copper can be found as either native copper or as part of minerals. There are many examples of copper-containing minerals: chalcopyrite and chalcocite are copper sulfides, azurite and malachite are copper carbonates and cuprite is a copper oxide. Copper is present in the Earth's crust at a concentration of about 50 parts per million (ppm), and is also synthesized in massive stars.
Most copper is mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits that contain 0.4 to 1.0% copper. Examples include Chuquicamata in Chile, Bingham Canyon Mine in Utah, United States and El Chino Mine in New Mexico, United States. According to the British Geological Survey, in 2005, Chile was the top mine producer of copper with at least one-third world share followed by the United States, Indonesia and Peru. The amount of copper in use is increasing and the quantity available is barely sufficient to allow all countries to reach developed world levels of usage.
More than 95% of all copper ever mined and smelted has been extracted since 1900. As of 2008, annual world production was around 18.4 million metric tons. As with many natural resources, the total amount of copper on Earth is vast (around 1014 tons just in the top kilometer of Earth's crust, or about 5 million years worth at the current rate of extraction). However, only a tiny fraction of these reserves is economically viable, given present-day prices and technologies.
Various estimates of existing copper reserves available for mining vary from 25 years to 60 years, depending on core assumptions such as the growth rate. Recycling is a major source of copper in the modern world. Because of these and other factors, the future of copper production and supply is the subject of much debate, including the concept of "Peak Copper", analogous to "Peak Oil".
The world's four largest copper producers are:
- BHP Billiton (NYSE: BHP) - World's largest mining company. A leading global producer of copper, silver, lead and zinc. Large, low-cost mining operations including the Escondida mine in Chile (world's largest single copper producer). BHP also mines iron, gold, aluminium, maganese, diamonds, coal, uranium and has proved oil reserves.
- Codelco - (CorporaciÃ³n Nacional del Cobre de Chile or, in English, the National Copper Corporation of Chile) is the Chilean state owned copper mining company formed in 1976 from the foreign owned copper companies that were nationalised in 1971.
- Freeport-McMoRan Copper & Gold (NYSE: FCX) - World's largest publicly traded copper company. FCX mines geographically diverse, long-lived reserves of copper, gold and molybdenum.
- Xstrata PLC (LSE: XTA)(OTC: XSRAY)(OTC: XSRAF) - World's fourth largest copper producer and one of the world's largest producers of smelter, refined and recycled copper, including from third party materials.
Lead is a chemical element with the symbol Pb (from Latin: plumbum) and atomic number 82. Lead is a soft, malleable poor metal. It is also a heavy metal with the highest atomic number of all of the stable elements. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a liquid.
Lead is used in building construction, lead-acid batteries, bullets and shots, weights, as part of solders, pewters, fusible alloys and as a radiation shield.
Lead, at certain exposure levels, is a poisonous substance to animals as well as for human beings. It damages the nervous system and causes brain disorders. Excessive lead also causes blood disorders in mammals. Like the element mercury, another heavy metal, lead is a neurotoxin that accumulates both in soft tissues and the bones. Lead poisoning has been documented from ancient Rome, ancient Greece, and ancient China. Lead usage has been restricted in many applications recently, such as paints.
Metallic lead does occur in nature, but it is rare. Lead is usually found in ore with zinc, silver and (most abundantly) copper, and is extracted together with these metals. Most ores contain less than 10% lead, and ores containing as little as 3% lead can be economically exploited. The main lead mineral is galena (PbS), which contains 86.6 % lead by weight. Other common varieties are cerussite (PbCO3) and anglesite (PbSO4).
Consumption and production of lead is increasing worldwide. Globally we use 8 kg of lead per capita; more-developed countries use 20-150 kg compared to less-developed countries that use 1-4 kg. In 2010, 9.6 million tonnes of lead were produced, of which 4.1 million tonnes came from mining, and the balance from recycled scrap. The top lead producing countries, as of 2008, are Australia, China, USA, Peru, Canada, Mexico, Sweden, Morocco, South Africa and North Korea. Australia, China and the USA account for more than half of primary production.
At current use rates, the supply of lead is estimated to run out in 42 years. This drops to only 18 years if an implied 2% growth rate is applied. This does not take into account renewed interest in recycling, and rapid progress in alternatives like fuel cell technology.
Nickel is a chemical element with the symbol Ni and atomic number 28. It's name comes from a mischievous sprite of German miner's mythology, Nickel (similar to Old Nick), that personified the fact that copper-nickel ores resisted refinement into copper. Nickel belongs to the transition metals and is hard and ductile. Nickel is one of only four elements that are magnetic at or near room temperature, the others being iron, cobalt and gadolinium. Nickel has a silvery-white lustrous color with a slight golden tinge, is corrosion-resistant and takes a high polish.
Nickel is reactive enough with oxygen that native nickel is rarely found on Earth's surface, however an iron-nickel mixture is thought to compose Earth's inner core. Nickel deposits are classified as either sulfide or laterite. Economically viable laterite deposits are huge but with lower concentration of the ore than sulfide deposits. The primary ore associated with sulfide deposits is Millerite. Nickel's most important modern ore minerals are laterites, including limonite, garnierite, and pentlandite.
Annual world nickel production was 1.4 million tonnes in 2007. Most of this comes from the Sudbury Basin deposit in Ontario Canada (30%, thought to be of meteoric origin), and the Norilsk deposit in Siberia Russia (40%). Other major nickel deposits are found in New Caledonia (French Pacific Island), Australia, Cuba and Indonesia.
The fraction of global nickel production presently used for various applications is as follows: 60% for making nickel steels; 14% in nickel-copper alloys and nickel silver; 9% to make malleable nickel, nickel clad, Inconel, and other superalloys; 6% in plating; 3% for nickel cast irons; 3% in heat and electric resistance alloys, such as Nichrome; 2% for nickel brasses and bronzes; 3% in all other applications combined.
Nickel is used in many specific and recognizable industrial and consumer products, including stainless steel, alnico magnets, coinage, rechargeable batteries, electric guitar strings, microphone capsules, and special alloys. It is also used for plating and as a green tint in glass. Nickel is preeminently an alloy metal, and its chief use is in the nickel steels and nickel cast irons, of which there are many varieties. It is also widely used in many other alloys, such as nickel brasses and bronzes, and alloys with copper, chromium, aluminium, lead, cobalt, silver, and gold (Inconel, Incoloy, Monel, Nimonic).
Usage of stainless steel is increasing with the growth of emerging economies; average growth rate for stainless steel production in the "BRIC" countries (Brazil, Russia, India, China) was 26.3% during the years 2001-2008. High nickel prices initiated a switch to 200-series steels that have 3.5-6% nickel content, rather than 8-10.5% in 300-series steels. A further reaction to high nickel prices in 2007 was the use of low grade nickel ore to create nickel pig iron as a substitute for refined nickel in China - not economical if nickel prices are below 24,000 USD per tonne.
As of September 16, 2011, the melt value of a U.S. nickel coin is $0.0600409, which is 20% higher than its face value. Nickel was once a common component of coins, but has largely been replaced by cheaper iron for this purpose, especially since the metal has proven to be a skin allergen for some people. Nickel was voted Allergen of the Year in 2008 by the American Contact Dermatitis Society.
Nickel is traded on the London Metal Exchange (LME). Nickel prices surged throughout 2006 and the early months of 2007; as of April 5, 2007, the metal was trading at 52,300 USD/tonne or 1.47 USD/oz. Then the financial crisis hit most metal prices including nickel, which fell dramatically to around 10,000 USD/tonne by early in 2009. As of June 25, 2012 the spot price of nickel was just over 17,000 USD/tonne.
The world's four largest nickel producers are:
- JSC MMC Norilsk Nickel (OTC: NILSY) - World's largest producer of nickel and palladium and one of the leading producers of platinum and copper. It also produces various by-products, such as cobalt, rhodium, silver, gold, iridium, ruthenium, selenium, tellurium and sulfur, with facilities in Russia, Australia, Botswana, Finland, and South Africa.
- Vale S.A. (NYSE: VALE)(NYSE: VALE.P) - World's second largest mining company, largest producer of iron ore, and second largest producer of nickel. Vale also produces manganese, ferroalloys, thermal and coking coal, copper, cobalt, platinum group metals, and fertilizer nutrients.
- BHP Billiton (NYSE: BHP) - World's largest mining company. A leading global producer of copper, silver, lead and zinc. BHP also mines iron, gold, aluminium, maganese, diamonds, coal, uranium and has proved oil reserves. BHP's Nickel West operations included the Ravensthorpe nickel-cobalt mine in Australia (sold at a loss to First Quantum Minerals (TSX: FM) in December 2009).
- Xstrata PLC (LSE: XTA)(OTC: XSRAY)(OTC: XSRAF) - World's fourth largest nickel producer with mining operations in Ontario and QuÃ©bec, Canada; Bonao, Dominican Republic; Western Australia; and Kristiansand, Norway. Xstrata Nickel also has a highly promising portfolio of growth projects, including Koniambo in New Caledonia, Kabanga in Tanzania, and Araguaia in Brazil.
Zinc is the 24th most abundant element in the Earth's crust; its chemical symbol is Zn and atomic number 30. Zinc is somewhat less dense than iron and is hard and brittle at most temperatures. Zinc is a fair conductor of electricity. Its melting point is the lowest of all the transition metals aside from mercury and cadmium. Zinc production includes froth flotation of the ore, roasting, and final extraction using electricity (electrowinning). Zinc is a bluish-white, lustrous, diamagnetic metal, though most common commercial grades of the metal have a dull finish.
The word zinc is probably derived from the German zinke, and supposedly meant "tooth-like, pointed or jagged" (metallic zinc crystals have a needle-like appearance). Zink could also imply "tin-like" because of its relation to German zinn meaning tin. Yet another possibility is that the word is derived from the Persian word سنگ seng meaning stone. The metal was also called Indian tin, tutanego, calamine, spinter, and spelter.
Brass, which is an alloy of copper and zinc, has been used since at least the 10th century BC. Impure zinc metal was not produced in large scale until the 13th century in India, while the metal was unknown to Europe until the end of the 16th century. Alchemists burned zinc in air to form what they called "philosopher's wool" or "white snow". Other metals long known to form binary alloys with zinc are aluminium, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium and sodium.
Corrosion-resistant zinc plating of steel (hot-dip galvanizing) is the major application for zinc. A variety of zinc compounds are commonly used, such as zinc carbonate and zinc gluconate (as dietary supplements), zinc chloride (in deodorants), zinc pyrithione (anti-dandruff shampoos), zinc sulfide (in luminescent paints), and zinc methyl or zinc diethyl in the organic laboratory.
Zinc is an essential mineral of "exceptional biologic and public health importance". Zinc deficiency affects about two billion people in the developing world and is associated with many diseases. In children it causes growth retardation, delayed sexual maturation, infection susceptibility, and diarrhea, contributing to the death of about 800,000 children worldwide per year. Enzymes with a zinc atom in the reactive center are widespread in biochemistry. Consumption of excess zinc can cause ataxia, lethargy and copper deficiency.
Zinc is normally found in association with other base metals such as copper, lead and iron in ores. Zinc is a chalcophile, meaning the element has a low affinity for oxides and prefers to bond with sulfides. Worldwide, 95% of the zinc mined is from sulfidic ore deposits; Sphalerite ZnS is the most heavily mined zinc-containing ore because its concentrate contains 60-62% zinc.
Identified world zinc resources total about 1.9 billion tonnes. Large deposits are in Australia, Canada and the United States with the largest reserves in Iran. At the current rate of consumption, these reserves are estimated to be depleted sometime between 2027 and 2055. About 346 million tonnes have been extracted throughout history to 2002, and one estimate found that about 109 million tonnes of that remains in use. The main zinc mining areas are China, Peru and Australia. China produced 29% of the global zinc output in 2010.
2006 Percentage of Zinc Output by Countries
Zinc is the fourth most common metal in use, trailing only iron, aluminium, and copper with an annual production of about 12 million tonnes. The world's largest zinc producer is Nyrstar (OTC: NYRSF), a merger of the Australian OZ Minerals and the Belgian Umicore. About 70% of the world's zinc originates from mining, while the remaining 30% comes from recycling secondary zinc. Commercially pure zinc is known as Special High Grade, often abbreviated SHG, and is 99.995% pure.
Major Applications of Zinc (US 2009)
- Galvanizing (55%)
- Alloys (21%)
- Brass and Bronze (16%)
- Miscellaneous (8%)
In 2009 the US used 893,000 tonnes of zinc for galvanization, the coating of iron or steel to protect against corrosion. The zinc is applied electrochemically or as molten zinc by hot-dip galvanizing or spraying of: chain-link fencing, guard rails, suspension bridges, lightposts, metal roofs, heat exchangers, car bodies etc.
The relative reactivity of zinc and its ability to attract oxidation to itself makes it an efficient sacrificial anode in cathodic protection (CP). For example, cathodic protection of a buried pipeline can be achieved by connecting anodes made from zinc to the pipe. Zinc acts as the anode (negative terminus) by slowly corroding away as it passes electric current to the steel pipeline. Zinc is also used to cathodically protect metals that are exposed to sea water from corrosion. A zinc disc attached to a ship's iron rudder will slowly corrode while the rudder stays unattacked. Other similar uses include a plug of zinc attached to a propeller or the metal protective guard for the keel of the ship.
Zinc is used as an anode material for batteries. (Even more reactive lithium is used for anodes in lithium batteries). Powdered zinc is used in this way in alkaline batteries and sheets of zinc metal form the cases for and act as anodes in zinc-carbon batteries. Zinc is used as the anode or fuel of the zinc-air battery/fuel cell.
A widely used alloy which contains zinc is brass, in which copper is alloyed with anywhere from 3% to 45% zinc, depending upon the type of brass. Brass is generally more ductile and stronger than copper and has superior corrosion resistance. These properties make it useful in communication equipment, hardware, musical instruments, and water valves.
Other widely used alloys that contain zinc include nickel silver, typewriter metal, soft and aluminium solder, and commercial bronze. Zinc is also used in contemporary pipe organs as a substitute for the traditional lead/tin alloy in pipes. Alloys of 85-88% zinc, 4-10% copper, and 2-8% aluminium find limited use in certain types of machine bearings. Zinc is the primary metal used in making American one cent coins since 1982. The zinc core is coated with a thin layer of copper to give the impression of a copper coin. In 1994, 33,200 tonnes (36,600 short tons) of zinc were used to produce 13.6 billion pennies in the United States.
Alloys of primarily zinc with small amounts of copper, aluminium, and magnesium are useful in die casting as well as spin casting, especially in the automotive, electrical, and hardware industries. These alloys are marketed under the name Zamak. An example of this is zinc aluminium. The low melting point together with the low viscosity of the alloy makes the production of small and intricate shapes possible. The low working temperature leads to rapid cooling of the cast products and therefore fast assembly is possible. Another alloy, marketed under the brand name Prestal, contains 78% zinc and 22% aluminium and is reported to be nearly as strong as steel but as malleable as plastic. This superplasticity of the alloy allows it to be molded using die casts made of ceramics and cement.
Similar alloys with the addition of a small amount of lead can be cold-rolled into sheets. An alloy of 96% zinc and 4% aluminium is used to make stamping dies for low production run applications for which ferrous metal dies would be too expensive. In building facades, roofs or other applications in which zinc is used as sheet metal and for methods such as deep drawing, roll forming or bending, zinc alloys with titanium and copper are used. Unalloyed zinc is too brittle for these kinds of manufacturing processes.
Cadmium zinc telluride (CZT) is a semiconductive alloy that can be divided into an array of small sensing devices. These devices are similar to an integrated circuit and can detect the energy of incoming gamma ray photons. When placed behind an absorbing mask, the CZT sensor array can also be used to determine the direction of the rays.
As a dense, inexpensive, easily-worked material, zinc is used as a lead replacement. In the wake of lead concerns, zinc appears in lab weights, tire weights, and flywheels. However zinc has its own concerns, as the production of sulfidic zinc ore produces large amounts of sulfur dioxide and cadmium vapor. Smelter slag and other residues of process also contain significant amounts of heavy metals.
Levels of zinc in rivers flowing through industrial or mining areas can be as high as 20 ppm. Concentrations of zinc as low as 2 ppm adversely affects the amount of oxygen that fish can carry in their blood. Soils contaminated with zinc through the mining of zinc-containing ores, refining, or where zinc-containing sludge is used as fertilizer, can contain several grams of zinc per kilogram of dry soil. Levels of zinc in excess of 500 ppm in soil interfere with the ability of plants to absorb other essential metals, such as iron and manganese. Zinc levels of 2000 ppm to 180,000 ppm (18%) have been recorded in some soil samples.
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