Aluminum: A Critical Mineral


Most residents of the United States think of foil, beverage cans, and recycling when we hear the word “aluminum” (or “aluminium”); then lots of other things come to mind, including vehicles, aircraft, and various items in our homes and offices.

Aluminum is even more widespread than we realize. As a metal, it’s also used in construction and for electrical power systems, including wires and cables. Many machines are made of aluminum, too.

As alumina–powdery aluminum oxide–it’s present in industrial refractories and many chemicals down to and including the main ingredients in styptic pencils and antiperspirants (alum–a naturally occuring aluminum salt–has been used as an astringent for centuries).

Aluminum is obviously common and inexpensive, so why is it on the US government’s 2018 “endangered minerals” list?

What is aluminum?

Let’s first look into why this element has two names–“aluminum” and “aluminium.” Both are correct, depending on the context, and each has been around since the 19th century.

Wikipedia and much of the world use “aluminium,” and that’s not wrong. In fact, Wikipedia has an excellent summary of the whole issue. Since I am from the US, where the American Chemical Society in 1925 settled on “aluminum,” this is the most comfortable spelling for me.

Aluminum is Earth’s most common metal, making up almost 10% of the planet’s crust, but you won’t ever find a natural chunk of it lying around, shining in the sun. Its chemistry always forces aluminum into combinations with many other elements.

To get our hands on this metal, we must break those chemical bonds apart. This is not easy to do, which is why two other minerals go with aluminum: bauxite (an aluminum ore) and alumina (the middleman between bauxite and aluminum metal).

Here is what it takes to get aluminum out of the ground:

  1. First, we look for bauxite, an ore of mineral compounds that forms when water leaches aluminum and other things out of thick tropical soil, concentrating them in a single layer that can be anywhere from 7 to almost 70 feet (2 to 20 meters) thick. Strip mining is the easiest way to get at bauxite, but this is small in scale. The total area of worldwide bauxite mining today would only cover about half of Manhattan Island. Bauxite can sometimes go straight to the alumina factory but it generally needs to be treated first, producing tailings and water/air emissions.

    Associated issues include soil problems, environmental pollution, and social unrest.


    bauxite

    Bauxite looks exactly as you would expect of an ore with that origin story. (James St. John, CC BY 2.0)


    Top sources of bauxite: In 2006, six countries–Australia, China, Brazil, Guinea, Jamaica, and India–contributed 85% of world bauxite production.



  2. About 10% of mined bauxite goes into things like abrasives, cement, ceramics, chemicals, and metallurgical uses. The rest is turned into alumina by way of the Bayer process. Remember, we must break the bonds between aluminum and other elements, so extraction of aluminum oxide is a very necessary middle step.

    Queensland Alumina Ltd

    Queensland Alumina Limited refinery, 1976. (Queensland State Archives, public domain)


    When this oxide forms naturally, the result is sometimes rubies or sapphires; when we do it, it’s simply a crystalline powder.

    According to data from 2005, it takes about 2-1/2 tons of bauxite to get 1 ton of alumina.

    Ninety percent of alumina production goes into making aluminum; the rest goes into chemicals and metallurgical materials.


    Associated issues: Red mud. This is really nasty stuff, though they are looking into ways to safely use it.


    Red mud pond

    Red mud settling pond near Stade, Germany. (Ra Boe via Wikimedia, CC BY-SA 3.0)


    Top sources of alumina: In 2006, six countries–Australia, Brazil, Russia, the US, and Jamaica–produced 72% of the world’s alumina.



  3. Aluminum metal is extracted from alumina using electrolysis (Caution: There are a couple of chemical formulas in this video, but there are also interesting visuals of Britons calmly going about their business near intense heat and gigantic machinery that is in motion, in a setting where two Terminators might be having a death match just offscreen):


    Associated issues: Obviously, production is energy-intensive, using a little over 14 megawatt/hours per ton of aluminum ingot produced. This is why many smelters are near hydropower dams and, in Iceland, also geothermal energy (aluminum companies have helped this country out of its economic woes, but their presence is controversial). The biggest environmental issue is greenhouse gases–CO2 from producing those 14 Mwh per ton and perfluorocarbons from the electrolysis (these don’t affect the ozone layer, but they have an even stronger greenhouse effect than CO2). Anode and aluminum fluoride are other waste products. As a side note, per Wikipedia, we have mined the native mineral cryolite to extinction in order to get aluminum metal; the cryolite used today as a solvent is artificial.


    Top sources of aluminum: According to the most recent data I could find online, the top five producers in 2016 were China, Russia, Canada, India, and the United Arab Emirates.

It’s quite a job to mine bauxite and turn it into aluminum, but it’s the best thing we’ve got right now. Since aluminum is so common, it’s also found in clay and many other natural materials, but extracting it from these sources would be even more arduous and expensive.

It’s much easier just to recycle.



Recycling of all sorts of aluminum, not just beverage cans, has been around since the early 20th century, but it really took off in the 1970s as an alternative to steel during the energy crisis. Recycled scrap and post-consumer aluminum is just as good as the original product, and it only takes about 6% of the power needed and some 10% of capital equipment costs to make..

Today, US consumption is split almost evenly between primary and secondary (recycled) aluminum.


welding-2178127_640

Aluminum consumption isn’t just about beverage cans. (emirkrasnic, at Pixabay)


Production is another matter.

Per the USGS 2018 mineral commodies study, US production of aluminum is the lowest it has been since 1951 and is 64% lower than it was in 2012, when we were the fourth-highest primary aluminum producer worldwide (now we’re #7, as of 2017).

By the end of 2015, about 27% of the total US aluminum production capacity was shut down, not counting permanently closed smelters.

The reasons for this dramatic downturn aren’t clear.

Why is aluminum a critical mineral to the US?

The news release about critical minerals simply says that aluminum is used in all sectors of the US economy. That’s as good a reason as any for critical importance, but it lacks detail.

Graedel and others (see sources below) say that the most concerning critical minerals are those that are mostly byproducts and used in small quantities for specialized markets, with no effective substitutes.

Aluminum doesn’t fit this at all. It’s a primary product (and recyclable); there’s lot of it around; and in a pinch a number of other materials can substitute for it in certain circumstances–magnesium, steel, copper, wood, titanium, graphite, paper, and fiber epoxies, according to the US Environmental Protection Agency (section 2.3.2).

That leaves supply-demand as an explanation for aluminum’s importance to the US economy and national security. And with a commodity like this–so common, with so many uses–things get complicated very quickly.


abstract-1869948_640

My general impression of the sociopoliticoeconomic global aluminum supply/demand situation. (EliasPix at Pixabay)


You don’t want to go there in this post, and neither do I. Let’s see what else we can do.

The US produces a lot of alumina, but it must import both bauxite (mainly from Jamaica, Brazil, Guinea, and Guyana) and aluminum metal (mainly from Canada, 56% per the USGS 2018 mineral commodities study, just hit by tariffs; Russia, 8%, which has been sanctioned; the United Arab Emirates, 7%; and China, 6%).

Clearly, from the tariffs and sanctions alone (let alone whatever must be going on behind the scenes!), aluminum is caught up in some global power plays at the moment.

The really peculiar thing is that, according to Papp and others (see source list), aluminum prices are at an all-time high, while world stocks are at an all-time low. This mystifies me because that big gap should be spurring aluminum production right now.

President Trump and others might not agree with the “all-time high prices” statement, saying instead that China’s state-supported sector is producing more aluminum that it can sell, driving aluminum prices down globally, though some experts are unconvinced.

It’s hard for those of us in the general public to understand what’s going on, but clearly aluminum has economic and political strategic importance on the international level, too.

I’m just going to close the post here, because the complexities of supply and demand are beyond this blog’s scope, and the current political and economic world situation with aluminum is volatile right now.

Below are some resources that can start you on your own exploration of aluminum as a critical mineral.



Featured image: Kristian Bjornard, CC BY-SA 2.0.



Sources:

Barry, J. J.; Matos, G. R.; and Menzie, W. D. 2013. US mineral dependence—Statistical compilation of US and world mineral production, consumption, and trade, 1990–2010 (No. 2013-1184). US Geological Survey.

Brown, T. J.; Idoine, N. E.; Raycraft, E. R.; Shaw, R. A.; and others. 2018. World Mineral Production 2012-16. British Geological Survey.

Cullen, J. M., and Allwood, J. M. 2013. Mapping the global flow of aluminum: From liquid aluminum to end-use goods. Environmental Science and Technology, 47(7): 3057-3064.

Graedel, T. E.; Harper, E. M.; Nassar, N. T.; Nuss, P.; and Reck, B. K. 2015. Criticality of metals and metalloids. Proceedings of the National Academy of Sciences, 112(14): 4257-4262.

Habashi, F. 1995. Bayer’s process for alumina production: a historical perspective. Bulletin for the History of Chemistry, 17(18): 15.

Hudson Institute of Mineralogy/Mindat.org. All pages accessed on May 30, 2018:

Los Alamos National Laboratory. n.d. Aluminum. periodic.lanl.gov/13.shtml Last accessed May 30, 2018.

Nappi, C. 2013. The global aluminium industry 40 years from 1972. World Aluminium, 1-27.

Organisation for Economic Co-Operation and Development (OECD). 2010. Global Forum on Environment Focusing on Sustainable Materials Management, Materials Case Study 2. Aluminium. PDF. Last accessed June 1, 2018.

Papp, J. F.; Bray, E. L.; Edelstein, D. L.; Fenton, M. D.; and others. 2008. Factors that Influence the Price of Al, Cd, Co, Cu, Fe, Ni, Pb, Rare Earth Elements and Zn. US Department of the Interior, US Geological Survey.

Price, A. H. n. d. Follow the money: The state financial sector and the aluminum and steel overcapacity crisis. OECD. PDF Last accessed June 1, 2018.

The Whatmans and Wove Paper website. n.d. In Defence of Alum – 1. The early history. http://www.wovepaper.co.uk/alumessay1.html Last accessed May 30, 2018.

US Geological Survey. n.d. Aluminum statistics and information web page (multiple links, generally the most recent or unique). Last accessed June 1, 2018. Most heavily used USGS sources include:

  • Bray, E. L. 2016. USGS 2015 Minerals Yearbook: Aluminum (Advanced Release). PDF.
  • Buckingham, d. A. 2005. Aluminum stocks in use in automobiles in the United States. https://pubs.usgs.gov/fs/2005/3145/ USGS Fact sheet 2005-3145.

Wikipedia. All pages accessed on May 30, 2018:

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