50 minerals critical to our society

The Energy Act of 2020, which directs an update of this list at least every three years, defines a “critical mineral” as a nonfuel mineral, element, substance, or material “essential to the economic or national security of the United States” and which has a supply chain “vulnerable to disruption.” Critical minerals are further characterized as serving at least one essential function in the manufacturing of a product, the absence of which would have significant consequences for the economy or national security.

As an example, according to Benchmark Mineral Intelligence, the demand for graphite among the battery sector is expected to rise 30 percent each year until 2030, and the nation is already in a deficit this year. The United States currently has zero manufacturing plants that can supply automotive-grade graphite. Meanwhile, China controls 84 percent of the global supply.

The 2022 List of Critical Minerals, as provided by the USGS on its website, is given below. To see the minerals’ uses and relevant statistics at the USGS web site, click the mineral names.

A year prior to the release of the USGS list, Simon Michaux, associate professor of geometallurgy at the Geological Survey of Finland, published his highly acclaimed report The Mining of Minerals and the Limits to Growth, about the amount of mining that will be required if the world continues as is, or attempts to quit using hydrocarbons. He determined that the rate-limiting step for achieving a decarbonized economy was copper.

Globally, we will need 4.2 billion tons of copper by 2050. However, throughout all of human history, we have mined only 700 million tons. Even if we do not decarbonize, we will still need another 700 million tons over the next 20 years just for business as usual. Unfortunately, we have already mined out most of the high-grade copper ores. Using lower-grade ores requires much more energy per ton recovered. This is an issue for many minerals.

Copper plays a larger role in renewable energy generation than it does in conventional thermal power plants in terms of tonnage of copper per unit of installed power, rising from approximately 1 metric ton of copper per megawatt installed in coal or nuclear plants to over 5 metric tons in onshore wind and solar, much of it used in the processes of connectivity to the grid, connectivity to each other, and storage systems.^, The amount of copper in offshore wind farms increases with the distance to the coast, averaging about 10 tons per megawatt. Germany’s Borkum Riffgrund-2 offshore wind farm uses 5,800 tons for a 400-MW, 200-km connection to the external grid—approximately 14.5 tons of copper per megawatt.

Of all power sources, nuclear is the least dependent on critical minerals.

Copper conductors are used in major electrical components, such as turbines, generators, transformers, inverters, electrical cables, power electronics, and information cables. Solar thermal heating and cooling energy systems rely on copper for their thermal energy efficiency benefits. Copper is also used as a special corrosion-resistant material in renewable energy systems in wet, humid, and saline-corrosive environments.

Fortunately, copper is 100 percent recyclable and has the highest recycling rate of any metal.

Human innovation can provide some technological solutions concerns surrounding mineral sourcing and supply. Advances in carbon nanotubes may provide a material as conductive and strong as carbon. For uranium, we are on the verge of economically extracting it from seawater.

Many of these elements are not directly mined but are recovered during the smelting or refining of the host rock or material for other commodities. These byproducts are typically chemically similar to their host material so are present in the same ores, but in smaller quantities. So refining copper ores allows us to recover significant amounts of tellurium, for example.

The recovery of byproducts is usually low relative to the total amount of material that was made available from mining, but the process to get the bigger prize makes recovery economical. This complicates the strategy for increasing the strategic supply of all of these elements as they are sometimes tied together.

A short geology lesson may be needed here. The List of Critical Minerals contains mostly elements—not minerals—although they are naturally found in rocks and purified by some form of smelting or separation method. A few listed, like fluorspar, actually are minerals.

The word “mineral” in this case is the old colloquial term for anything not animal or vegetable and includes many things that are not actually minerals, like oil and gas. Geologically speaking, a mineral is any naturally occurring crystalline substance that has a fixed physical structure (arrangement of atoms in space) and a chemical composition that varies within strict limits.

So those cool quartz crystals are made of a mineral having a chemical composition of silicon dioxide (commonly known as silica) and a structure with the oxygen atoms arranged in a tetrahedron around each silica atom. But glass, also made of silica, is not a mineral, as it has no fixed structure, being just a quenched liquid. (Remember those wavy 100-plus-year-old glass windows that have flowed under gravity so the glass is thicker at the bottom? Very pretty.)

A rock is an aggregate of minerals that may also consist of only one mineral. Calcite- or silica-cemented pebbles in nature are called conglomerates, similar to man-made concrete. But concrete is not a rock.

Regardless of how you discuss them, these elements are critical to our lives—especially if you’re reading this on a screen.

James Conca is a scientist in the field of earth and environmental sciences specializing in geologic disposal of nuclear waste, energy-related research, planetary surface processes, radiobiology and shielding for space colonies, and subsurface transport and environmental cleanup of heavy metals.

References:

1. “U.S. Geological Survey releases 2022 list of critical minerals,” national news release, Feb. 22, 2022; usgs.gov/news/national-news-release/us-geological-survey-releases-2022-list-critical-minerals.
2. Simon P. Michaux, The Mining of Minerals and the Limits to Growth, Geological Survey of Finland report no. 16/2021, Jan. 2021; tupa.gtk.fi/raportti/arkisto/16_2021.pdf.
3. Edgar G. Hertwich et al., “Integrated life-cycle assessment of electricity-supply scenarios confirms global environmental benefit of low-carbon technologies,” Proceedings of the National Academy of Sciences 112, 20 (2015); doi.org//10.1073/pnas.1312753111.
4. Konrad J. A. Kundig, with BBF Associates, “Market study: Current and projected wind and solar renewable electric generating capacity and resulting copper demand,” July 2011; copperalliance.org.
5. James L. Conca, “Uranium extraction from seawater makes nuclear power virtually renewable,” in vol. 2, part 5, Encyclopedia of Nuclear Energy, ed. Ehud Greenpsan, pp. 277–85, Elsevier (2021).