Magnesium as the Metal of Dematerialization

By Alex Grant, Magrathea.

In 1944, Willard Dow told the U.S. Senate, “There is an epic quality involved in [taking] a ladle of gleaming metal out of a curling, white-capped ocean wave. Not even the old alchemists, in their wildest fancies, ever got that far.”¹ Dow Magnesium was once the largest magnesium metal producer of all time, extracting millions of tonnes of metal from seawater over the century-long lifetime of their Freeport, TX, operation (Figure 1).² The Dows were mesmerized by the technology they created. They believed magnesium from seawater was a step forward in human civilization.

Magnesium has many advantages: common alloys are a third lighter than aluminum and three to four times lighter than steel. Magnesium is easy and economical to die cast, lending itself to mass manufacturing and making it a much more scalable material than other lightweighting options like carbon fiber composites. But it was not strictly its technical properties that enthralled the Dows. They loved magnesium because it is also the only structural material that can be made from seawater (Figure 2).

Despite the success of Dow’s seawater metal operation, magnesium did not develop into a large global industry. Most lightweighting product categories went to aluminum, and today the world uses around 50 times more aluminum by mass. There is at least one reason why magnesium struggled to compete: it failed to tell its own story, or at least tell it well enough to convince potential customers to invest away from aluminum and steel. In 1966, Roger Wheeler, the International Magnesium Association president at the time, excoriated his own members, saying that “sophisticated marketing know-how has been notably absent in the magnesium industry.”³ And in 2003, Gerald Cole, a former Ford engineer, lamented that “a major problem with magnesium is that there are not enough zealots in the supply base.”⁴

Few people will invest in product development using magnesium unless the technical and marketing benefits are clear, and in the 20^th century, few understood what the Dows saw in magnesium: an opportunity to make metal without mining. The 21^st century, however, is a different story.

Everything is Changing

This is a decade of radical change. The COVID-19 pandemic and Russia’s war in Ukraine have crystallized for many people the importance of establishing shorter and cleaner supply chains in countries that share their values.⁵ Increasingly, those values are focused on reducing environmental and social impacts of civilization, while maintaining a high quality of life. Decarbonization to mitigate climate change has become a dinner table topic, but decarbonization is only part of the story. After all, carbon neutral technologies can still have severe impacts on the environment. A decarbonized tailings dam at a mining operation, for example, can still ruin ecosystems and kill people if it collapses. Ultimately, the best tailings dam is one that does not exist.

Dematerialization, on the other hand, is technology innovation focused on “doing more with less” by, for instance, achieving higher economic output per mass of natural resources consumed.^6-7 Almost all new technology creates value for customers by increasing the quality of a product or decreasing the quantity of resources required to make a product.⁸ Smartphones, solar energy, and batteries are just three examples of products that achieve radical dematerialization. What’s more, the growing focus on reducing the environmental and social impacts of supply chains will only accelerate dematerialization across many industries.⁹ In light of these trends, the Dows’ vision for magnesium appears prophetic (Figure 3).

Magnesium Use for Dematerialization

Smartphones were adopted to dematerialize information by providing access to vast amounts of knowledge from a single hand-held source. Solar, wind, and battery technologies are being deployed to dematerialize energy. In the same way, magnesium metal made from seawater without mining, using electrochemical technology like that deployed commercially for decades by Dow and Norsk Hydro, is the only way to dematerialize primary metal.¹⁰

Magnesium’s radical lightweighting feature allows it to eliminate up to 75% of dead weight from some metal parts used in vehicles, providing a literal dematerialization that allows consumers to move farther using the same amount of energy. This supports the decarbonization of transport that has been contemplated for decades via the implementation of CAFE standards in the U.S.¹¹ In the era of electric vehicles, the use of magnesium rather than aluminum and steel will allow automakers to use fewer batteries in each car to provide consumers the same driving range, a critical advantage as lithium-ion battery supply chains buckle under rapid growth.

The family of electrochemical technologies used by companies like Dow, Norsk Hydro, and others involves four main steps: hydrometallurgy, dehydration, electrolysis, and metal foundry. In the first step, brine concentrates are obtained from seawater or from waste brines produced from potash or sea salt operations. These brine concentrates are purified and evaporated until they contain pure magnesium salt hydrates. Once obtained, they are processed using various types of dehydration technology to produce anhydrous magnesium salt without any water. Every time that electrochemical magnesium was ever developed or deployed, a different dehydration technology was used, so dehydration technology has never consolidated into one approach. Then, the anhydrous magnesium salt is melted and electrolyzed to make magnesium metal. This metal is “tapped off” from electrochemical cells and can be used to make a variety of products, including pure ingots for the aluminum industry, alloyed ingots for die casting, or sent straight to casting without ever letting the metal solidify. The only byproducts of this process are water, chlorine, and a small amount of impurities that are removed from the brine, with no major slag production.

By comparison, the Pidgeon process deployed by Chinese producers in the 1990s and early 2000s, works completely differently and does not lend itself well to future growth. It uses an immense amount of energy as high temperature heat and directly emits carbon dioxide in the calcination of magnesite ores, in the production of reductants like ferrosilicon, and in the generation of the high temperature heat used to operate the process. Despite its downsides, the Pidgeon process benefits from a cost structure that is dependent on energy from burning coal and from cheap human labor. This has made it nearly impossible for Western producers to compete with Chinese producers, especially after the Chinese government created rebates to incentivize export of cheap, dirty metal.¹²

However, the magnesium market is beginning to see a shift. Producers in China are now struggling to access coal power and cheap labor, as the country works to decarbonize its industries and most of its people start entering the middle class. In addition, electrochemical magnesium will benefit enormously from the growth of solar energy and batteries, unlocking potential for low-cost production in new geographies.

As renewable energy sources like solar, wind, and geothermal drive down the cost and carbon emissions of electricity and as carbon taxes and other measures from governments around the world make it more expensive to emit carbon dioxide, magnesium producers will begin to see that there is no technological or economic incentive to directly emitting carbon dioxide. By comparison, the electrochemical production process using seawater, which is inherently decarbonizable, will begin to look more attractive. In fact, electrochemical magnesium production is so attractive for the future that even China is trying to ramp down its dirty, labor-intensive Pidgeon operations in favor of a newly commissioned plant producing magnesium from brine using electrochemical technology.¹² Soon, producing magnesium with electrochemical technology could become one of the most economically competitive pathways to lightweight metal in the world.

Similarly, magnesium is easier to decarbonize than primary aluminum or steel production. Using conventional technologies, aluminum and iron reduction both require oxygen removal using carbon. These processes are responsible for 10% of the world’s carbon dioxide emissions. While startups spend hundreds of millions of dollars and decades trying to figure out how to make steel and aluminum without emitting carbon dioxide, magnesium metal has already been made without direct carbon dioxide emissions for a century. In addition to the inherent lack of oxygen in magnesium salts, magnesium electrolysis occurs at much lower temperatures than aluminum electrolysis and steel production, which means that it consumes far less energy.

The production of primary magnesium has the potential to be some of the cleanest extractive metallurgy in the world, but there are even more benefits of the metal at the end of its life. Magnesium turns into magnesium hydroxide when it corrodes and eventually returns to the ocean as a soluble bicarbonate. When it ends up in this form, it is able to automatically sequester carbon dioxide. It can then be produced from seawater without emitting carbon dioxide back into the atmosphere. This makes magnesium the only inherently circular structural metal.

Aluminum and steel are doomed to have linear value chains. They will always require inputs of solid mineral natural resources and will always output wastes that do not sequester carbon dioxide or re-appear in the same place from where they came. All metals can be recycled, but never infinitely: metal is always lost to dross or slag every time it is recycled, so metals like aluminum can only be recycled an average of 10-15 times before it becomes lost to waste.¹³

Magnesium from seawater eliminates the need to mine solid mineral resources and eliminates the production of tailings, both of which can inflict significant harm. Iron ore mining, for example, can cause severe impacts like the destruction of Juukan Gorge in Australia, which led to the resignation of Rio Tinto’s CEO.¹⁴ Mining iron ore and bauxite have both led to tailings dam collapses, destroying ecosystems, and killing thousands of people. Substituting mining with magnesium from seawater is the only way to eliminate these harmful environmental and social impacts.

Back to the Future

The world will always need mining to produce some metals. Aside from breakthroughs in alloy development, magnesium is not going to be able to perform some of the functions of steel and aluminum, at least not for a long time. Even so, it is possible to minimize the amount of mining necessary for maintaining society’s high quality of life and continue human economic development by using much more magnesium metal in vehicles and beyond.

As demonstrated by Volkswagen and the major automakers for decades, magnesium is a phenomenal material that is dramatically underutilized as a tool for the decarbonization and dematerialization of transport.¹⁵

At your next dinner party, tell your guests that we can make electric vehicles, bicycles, helicopters, eVTOL aircraft, satellites, and planes from seawater. In fact, all these things have already been made from magnesium. Magnesium metal made without mining offers hope for a better future where abundance reigns and impacts on the planet are low. Magnesium from seawater is the metal that should carry us through the 21^st century.

The Dows had this vision 100 years ago, but only now with the rise of climate and social impact conscience has its time truly come. The revival of low-carbon emission magnesium metal without mining would be the ultimate “back to the future” technology breakthrough.

References

1. Dow, Willard Henry, Dow and Magnesium, The Dow Chemical Company and the University of Michigan, 1944.
2. “75 Years of Magnesium at Freeport,” Light Metal Age, June 1991, pp. 30–31.
3. “Magnesium: What’s Wrong with It and What to Do with It,” Light Metal Age. June 1966, pp. 17–18.
4. Cole, Gerald, “Issues that Influence Magnesium’s Use in the Automotive Industry,” Materials Science Forum, Vol. 419–422, March 2003, pp. 43–50, DOI:10.4028/www.scientific.net/MSF.419-422.43.
5. Enslen, Alan F. and John M. Scannapieco, “Managing Global Supply Chains in a Volatile World,” The National Law Review, November 4, 2022.
6. McAfee, Andrew, “Dematerialization and What It Means for the Economy – and Climate Change,” Harvard Business Review, September 17, 2019.
7. Konietzko, Dr. Jan, “Moving Beyond Carbon Tunnel Vision With a Sustainability Data Strategy,” Forbes, April 7, 2022.
8. Fey, Victor, Innovation on Demand: New Product Development Using TRIZ, Cambridge University Press, January 2010.
9. Steinberger, Julia K., et al., “Development and Dematerialization: An International Study,” PLoS One, Vol. 8, No. 10, 2013, National Library of Medicine.
10. “Norsk Hydro’s Magnesium Production at Porsgrunn, Norway,” Light Metal Age, August 1979, pp. 24-25, 40.
11. “Corporate Average Fuel Economy Standards for Model Years 2024-2026 Passenger Cars and Light Trucks,” Federal Register, May 2, 2022.
12. Baker, Phil, “Pidgeon or Electrolytic Technology – The Choice for Modern China,” 73^rd World Magnesium Conference, Rome, Italy, May 15–17, 2016.
13. Das, Subodh and Martin Hartlieb, “Addressing the Problem of Greenwashing in the Aluminum Industry,” Light Metal Age, August 2022, pp. 18.
14. Albeck-Ripka, Livia, “Executives to Step Down After Rio Tinto Destroys Sacred Australian Sites,” New York Times, September 11, 2020.
15. Holrigl-Rosta, F. “Magnesium in the Volkswagen,” Light Metal Age, August 1980, pp. 22–23, 26-29.

Editor’s Note: This article first appeared in the February 2023 issue of Light Metal Age. To receive the current issue, please subscribe.