1.3 What are critical commodities?

1.3.1 Definition of critical commodities

The terminology and use of ‘critical’ in the context of raw materials, chemical elements, and minerals is problematic, in part due to the multiple meanings of the word in the English language and also due to the different methodologies used to assess which materials are critical in various studies. The terms ‘critical’ and ‘strategic’ also are used loosely in this context. This report differentiates these terms and focuses only on the critical commodities, although some critical commodities also may be strategic for some countries.

There appears to be a convergence of views, captured in the following quotes from two key studies. The US National Academy of Sciences (2008) report on Minerals, Critical Minerals, and the U.S. Economy proposed that ‘a mineral can be regarded as critical only if it performs an essential function for which few or no satisfactory substitutes exist’, and ‘in addition, a mineral can be regarded as critical only if an assessment also indicates a high probability that its supply may become restricted, leading either to physical unavailability or to significantly higher prices for that mineral in key applications’. In this report the word ‘mineral’ is used in a very broad sense to include individual chemical elements (metals and non-metals) and minerals sensu stricto (see Break-out 1.3.1).

The European Commission (2010) report on Critical raw materials for the EU stated: ‘a raw material is labelled critical when the risks of supply shortage and their impacts on the economy are higher than for most of the other raw materials’.

Break-out 1.3.1. Definitions

Metals are chemical elements that ‘have a characteristic lustre, are good conductors of heat and electricity, and are opaque, fusible, and generally malleable or ductile’ (Neuendorf et al., 2005). Most metals occur in nature as compounds within minerals although some important metals such as gold, copper and platinum also occur naturally in elemental (native) form. Among metals there are several subgroups, including transition metals (such as iron, zinc, copper), noble metals (such as gold, platinum, palladium), alkaline earth metals, etc. Semi-metals have characteristics that are transitional between metals and non-metals, such as semi-conductance of electricity.

A mineral is ‘a naturally occurring inorganic element or compound having a periodically repeating arrangement of atoms, and characteristic chemical composition, resulting in distinctive physical properties’ (Neuendorf et al., 2005).

A mineral deposit is a ‘mass of naturally occurring mineral material, e.g. metal ores or non-metallic minerals, usually of economic value, without regard to mode of origin’ (Neuendorf et al., 2005).

A mineral system is ‘all geological factors that control the generation and preservation of mineral deposits’ (Wyborn et al., 1994).

Both the US and EU studies developed concepts of criticality involving simple 2-dimensional matrices, which express the combination of importance in use and availability or supply risk of the material in question (Figures 1.3.1, 1.3.2). As noted in the introduction, there are many factors contributing to each of these two dimensions—for example, supply risk will be influenced by (1) scarcity of the commodity; (2) geopolitical stability of suppliers; (3) diversity of supply and market scale; (4) method of recovery (e.g., as the main product or as a by-product); and (5) level of concentration of commodity production and processing within particular countries.

Figure 1.3.1 This diagram plots critical commodities qualitatively as a function of supply risk (abscissa) and impact of supply restriction (ordinate). Commodities with greater criticality (for example, rhodium, platinum, palladium, rare earth elements, manganese, indium and niobium) plot in the upper right of the diagram.

Figure 1.3.1: US National Academy of Sciences (2008) criticality matrix.

This report uses the term ‘commodity’ to cover the wide range of 34 metals, non-metals and minerals studied. These commodities were selected based on an initial review of previous studies of raw materials criticality by different countries. From this list we have assessed the overall criticality, and made judgements about the resource potential for Australia for each commodity (see Section 1.5).

Most of the critical commodities considered in this report are metals and semi-metals; the remainder are non-metallic elements (such as helium, a noble gas), or minerals (such as graphite, a crystalline form of carbon), or rocks (which are composed of aggregates of one or more minerals, such as bauxite).

Figure 1.3.2 This diagram plots critical commodities qualitatively as a function of economic importance (abcissa) and supply risk (ordinate). Commodities with greater criticality (for example, rare earth elements, platinum group elements, niobium, tungsten, graphite and others) plot in the upper right of the diagram.

Figure 1.3.2: European Commission (2010) criticality matrix for the European Union.

1.3.2 Uses of critical and other metal and mineral commodities

The periodic table of the elements (Figure 1.3.3) illustrates the groupings of elements with certain shared physical and chemical properties. For example, all metals are good conductors of electricity and are generally malleable and ductile, whereas semi-metals are semi-conductors of electricity, a highly valuable property in electronics and solar energy panels. Some sub-groups have particular shared properties, for example platinum-group elements (including platinum and palladium) and other noble metals such as gold are highly resistant to chemical corrosion.

Other metals are valued for their extremely high melting temperatures and hardness, such as tungsten and rhenium, so that alloys of these metals tend to have greater tensile strength at high temperatures. This property enables rhenium-bearing super-alloys in jet engine turbine blades to operate at higher temperatures than non-rhenium turbines (break-out 1.3.2), reducing aeroplane emissions and fuel costs.

The rare-earth elements, which include the lanthanide series metals as well as scandium and yttrium, have diverse and very useful properties. For example, small percentages of neodymium and dysprosium in some alloys increase permanent magnet strength by orders of magnitude, enabling step changes in miniaturising of telecommunications and other electronic devices, and much more efficient generation of electricity in commercial wind turbines.

Figure 1.3.3 This figure contains two periodic tables. Table (a) illustrates groups of elements with similar chemical properties. Highlighted groups include metals, metalloids and non-metals.

Figure 1.3.3 This figure contains two periodic tables. Table (b) illustrates the the status of production, development and exploration for all elements in Australia. The elements are divided into five groups. The first group includes gases and artificially produced elements. With the exception of helium, these elements are not produced or explored for in Australia. The second group includes elements that are currently produced as main commodities in Australia. In most cases, active exploration is presently underway for these elements. The third group includes elements for which resources (both demonstrated and inferred) have been identified, but which are not produced as main commoditions in Australia. The may, however, be produced as by-products in Australia. The fourth group includes elements that are not produced as main products or by-products in Australia, but are the subject of active exploration in Australia. These commodities may be recovered in downstream processing of concentrates. The last group includes elements that are not produced or currently being explored for in Australia. For more information contact clientservices@ga.gov.au.

Figure 1.3.3: Periodic tables of the elements showing (a) metals, semi-metals (metalloids) and non-metals with sub-groups, and (b) the status of production, development and exploration in Australia.

This photograph is of the intake of a jet turbine and illustrates one of the important uses of rhenium.

Image: Tony Hisgett,
Wikimedia Commons.

Break-out 1.3.2. The use of rhenium in high temperature turbines in the aerospace industry
Operating Property - testing this table Non-Rhenium Turbine Rhenium Turbine
*Source Rio Tinto December 2008 Review.
1 The values X and Y refer to nominal power and thrust and efficiency for non-rhenium turbines. The formulae for rhenium turbines indicate improvements in these parameters.
Operating temperature ˜2000–2200° F ˜3000° F
Power and thrust X1 Approximately 2X
Fuel Efficiency Y1 Y + (40–60%)
Emissions* Carbon dioxide 64% reduction
Nitrogen oxide 88% reduction
Sulphur dioxide 99.9% reduction
Particulates Eliminated
Approximate Rhenium contained per turbine 0 kg ˜25 kg (3% alloy)

Table 1.3.1 lists some of the key drivers of the technologies in which major as well as minor commodities are used, many of which are considered critical (see Sections 1.4, 1.5). The commodities assessed in this report are shown in bold. Break-out 1.3.3 illustrates the use of mineral commodities in the construction of a typical motor car. Other drivers are the production and use of low-emissions energy, which is likely to see extensive growth in the short, medium and long terms, and the communications and entertainment technology industries.

Table 1.3.1: Common uses of metals, non-metals and minerals in industrial and high-technology applications.
Driver of metal/material usage Technology/product Commodities used; bold indicates critical commodities in this study
Industrial production efficiency and infrastructure development Steel Fe, Cr, V, Mo, Ni, Co, Mn
Catalysts PGE (Pt, Pd)
Ceramics Li, Ce
Paint Ti, Cr
Moulds Zr
Flame retardant Sb
Cryogenics He
Low-emissions energy production Wind turbines—permanent magnets REE (Nd, Dy, Sm, Pr)
Photo-voltaics (PV) In, Sb, Ga, Te, Ag, Cu, Se
Nuclear reactors U, Th, Zr
Low-emissions energy usage Electric cars—batteries REE (La, Ce, Nd, Pr), Li, Ni, Co, Mn, graphite
Electric cars—magnets REE (Nd, Dy, Sm, Pr)
Electric cars—fuel cells PGE, Sc
Cars—light metals Al, Mg, Ti
Cars—catalytic converters PGE
Communications and entertainment technologies Wires Cu
Micro-capacitors—mobile phones etc Ta, Nb, Sb
Flat screens—phosphors In, Y
Fibre optics and infra-red Ge
Semiconductors Ga
Defence / security Nuclear/radiation detectors He
Armour and weapons Be, W, Cr, V
Aerospace—superalloys Re, Nb, Ni, Mo
Transport—fuel efficiency & performance Light alloys Superalloys (high-temperature performance e.g. in jet engine turbines) High speed trains—magnets Al, Mg, Ti, Sc, Th Re, Nb, Ni, Mo Co, Sm
Water & food security Water desalination PGE, Cr, Ti
Agricultural production—fertiliser Phosphate rock; potash, Mg
These photographs illustrate the use of critical commodities in modern automobiles. From left to right, the photographs illustrate (a) a modern automobile, (b) an automotive tyre and (c) automotive electrical components. Fabrication of modern automobiles require a range of critical commodities, including manganese, chromium, nickel, magnesium, molybdenum, vanadium and platinum.

(a) http://flickr.com/people/robadob,
Wikimedia Commons,
(b) Larry D. Moore,
Wikimedia Commons,
(c) Petter73, Wikimedia Commons.

Break-out 1.3.3. Metal and other selected element usage in the manufacture of an average car in 2006 (from United States National Academy of Sciences, 2008)
Element/material Mass (kg) Property (use)
Iron and steel 963 High strength, durability (frame, engine)
Aluminium 109 Light weight (frame, engine)
Carbon 23 Bond strengthener (tyres and other rubber parts)
Copper 19 Electrical conductivity (wiring)
Silicon 19 Bonding properties (windows)
Lead 11 Conductor (storage batteries)
Zinc 10 Galvaniser, strengthener (galvanised metal and alloy parts)
Manganese 8 Hardness as metal alloy parts
Chromium 7 Corrosion resistance and hardness as metal alloy
Nickel 4 Strength at elevated temperature and corrosion resistance as metal alloy
Magnesium 2 Light weight alloying element with aluminium
Sulfur 0.9 Strengthens rubber tyres
Molybdenum 0.45 Strength and toughness as metal alloy
Vanadium <0.45 Strength and toughness as metal alloy
Platinum 1.5–3.0 grams Catalytic properties (catalytic converters)
Note: In addition to the elements listed above, the average car also contains trace amounts of antimony, barium, cadmium, cobalt, fluorspar, gallium, gold, graphite, halite, limestone, mica, niobium, palladium, phosphorus, potash, strontium, tin, titanium and tungsten.