Base metals are widely used as manufactured products or in industrial applications. Their utility and ubiquity make them among the most actively traded commodities. For the economically most important of them, we more than briefly describe, production and usage.
Aluminium is very abundant (8.13% or 81300 ppm of the earth's crust), mainly as bauxite. Bauxite is first dissolved to Alumina (aluminium oxyde) , from which aluminium metal is recovered by electrolysis. The process is very energy consuming (above 13 MWh per ton of Aluminium).
Aluminium is a light and strong, grey metal, good conductor of heat and electricity. Main usages are: transportation and building material, packaging and wrapping material, electricity conduction, consumer durables.
More on aluminium: International Aluminium Institute .
Unalloyed aluminium as well as a variety of alloys are traded. The most adopted alloys classification are those registered by the Aluminum Association , which is re-used in the UNS codes.. The aluminium grades of particular importance in trading are detailed in a nutshell hereafter.
Copper ore is available natively or in minerals (55 ppm of the earth's crust). Those are converted to copper by pyro- or hydrometalurgy, followed by electrolysis.
Copper is a pink to red metal, very good electrical conductor. Main usages are: construction, electric and electronic products, transportation and equipments, consumer products. It is often mixed with with other metals to obtain alloys for particular purposes: brass (zinc), bronze (tin), cupro-aluminium, cupro-nickel.
More on copper: Copper Alliance or Copper Development Association .
Stone layers containing lead abound in nature (15 ppm of the earth's crust). The main mineral is galena. Lead is a bluish-grey, soft, very malleable metal. Main usages are: batteries, pigments, rolled products, alloys.
In mining, Nickel occurs most combined with iron ans sulfur.
Nickel is a Silver-grey metal that is hard, malleable and ductile. Main usages are: stainless steel production, superalloys, plating, steel alloys.
Mainly found in cassiterite, tin is less widespread in nature (2 ppm of the earth's crust).
Tin is a silvery, white metal that is malleable and ductile. Main usages are: anti-corrosion coating, cans and boxes, alloys with other metals, bronzes, glass-making.
Fairly widespread in nature (70 ppm of the earth's crust), zinc is found in a variety of ores and minerals.
Main usages of Zinc are: anti-corrosion galvanization (coating, alloys), die casting (alloyed with other metals), building industry (roofing), chemical industry.
The base metals market is dominated by the London Metal Exchange (LME) contracts. However markers are available for specific qualities or locations. Very often a double quote is released: premium towards the LME Cash price, and a so-called all-in, transaction or equivalent fix price, which adds the premium to the prevailing LME cash price to obtain an outright price.
The base metals market is dominated by the London Metal Exchange (LME). Other exchanges list contracts, outright or quoted as a premium or discount towards the corresponding LME metal.
LME contracts can be delivered in any LME warehouse, which are spread around the globe. Preference of the operators for particular locations underpins an active 'warrants' market, which is when the future contract transforms into an effective entitlement to metal, located in a specified warehouse.
Aluminium alloys are subdivided by material composition and fabrication method:
Wrought: material is heated and then extruded to sheets, tubes or rods.
The Aluminum Association designates wrought aluminum alloys by a 4-digit code, which first digit indicates the serie, or major alloying metal (1 99% Al, 2 Cu, 3 Mn, 4 Si, 5 Mg, 6 Mg+Si, 7 Zn, 8 Others).
Cast: material has been melted then poured into a mold.
The AA nomenclature is a 3-digit code, which first digit designates the major alloying metal (1 99% Al, 2 Cu, 3 Si+Cu/Mg, 4 Si, 5 Mg, 7 Zn, 8 Sn, 9 Others). This code can be prefixed by a letter (A indicating a higher purity of composition, B, C, ...) and suffixed by a number (.0 for Casting, .1 for Ingot).
A further distinction is made between primary and secondary, the recovery rate from scrap being very high in the aluminium industry.
High grade Aluminium, (in %: 99.7 Al, max 0.1 Si, max 0.2 Fe).
Quality eligible for LME AH delivery.
|Wrought alloy||6022||Sheet (automotive) alloy (in %: 98.7 Al, 0.4 Si, 0.6 Mg, 0.05 Mn, 0.05 Cu, 0.3 Fe).|
|6063||Universal structural alloy (in %: 97.9 Al, 1.1 Si, 0.7 Mg).|
|319||LM 4||AC2B||in %: 5.5-6.5 Si, 3.0-4.0 Cu, 1.0 Zn, 0.8 Fe|
|356||LM 25||Al-Si7Mg||Suitable where good corrosion resistance combined with thermal properties are required.|
|A380||LM 24||Al-Si8Cu3Fe (226)||AD12.1||
Alloy formulated for casting (in %: 79.6 to 89.5 Al, 7.5 to 9.5 Si, 3.0 to 4.0 Cu), furnished as fabricated, without temper or treatment.
Quality eligible for LME AA and LME NASAAC delivery.
|383, 384||LM 2||ADC 12||in %: 9.6-12 Si, 1.5-3.5 Cu, 1.0 Zn, 0.9 Fe, 0.5 Mn, 0.3 Mg|
|A413.0||LM6, LM20||Al-Si12 (230, 231)||Casting alloy with up to 11.0% Si.|