アーカンソーは私たちのリチウム需要への答えを持っているか？

リチウム供給の重要性

Lithium has quickly become a very important commodity, largely due to the rise of EVs and renewable energy and its associated massive demand for lithium-ion batteries. The demand is expected to persist in growing exponentially until 2030, making the current 1,189,000 MT lithium carbonate equivalent (LCE) demand look small in comparison.

出典: Statista

リチウムイオンは将来的にやや時代遅れの技術になる可能性がありますが、リチウムはバッテリー化学の重要な要素であり続けるでしょう。特にリチウム金属固体電池が主流になる場合はなおさらです。

この需要の増加はリチウム価格の変動を招き、供給不足が大きな価格急騰を引き起こし、その後急落するという状況が繰り返されています。

出典: Carbon Credit

これによりリチウム供給の確保が戦略的課題となっています。特に、電力会社から自動車メーカーまで、ますます多くの産業が安定したリチウムバッテリー供給に依存するようになっています。

現在、世界のバッテリーと精製リチウムの大部分は中国から供給されています。この鉱物自体は主に「リチウムトライアングル」（チリ、アルゼンチン、ボリビア）、中国、オーストラリアで採掘されています。

出典: Progress in Natural Science

Lithium production has been rather slow in North America despite large resources. These resources have now been revealed to be even larger, with massive lithium deposits discovered in Arkansas. This discovery was made by researchers at the US Geological Survey, Arkansas Department of Energy and Environment, and published in Science Advances under the title “機械学習を用いた南アーカンソーのスモックオーバー層塩水におけるリチウム資源の評価”.

新たなリチウムトライアングル？

The lithium triangle is this border zone in South America between 3 countries that contains massive amounts of lithium-rich brines, from which a large percentage of the world’s lithium comes.

米国にも、アーカンソー、テキサス、ルイジアナの交差点に独自のリチウムトライアングルがあるようです。

出典: Science Advances

And the discovery is massive, potentially doubling overnight the estimated US lithium resources.

Using these predicted lithium maps with reservoir parameters and geologic information, we calculated that there are 5.1 to 19 million tons of lithium in Smackover Formation brines in southern Arkansas, which represents 35 to 136% of the current US lithium resource estimate.

どのように発見されたか？

This was already known that the oil & gas deposits in the area were also rich in brines containing bromide and lithium. However, previous analyses could only give an indication of the lithium content at the brine sample location, with a wide range of results, from 0.08 to 1700 mg/liter.

So the researchers deployed an AI analysis to bring together all the known measurements and the geological data of the region. As the area has been extensively explored for oil & gas production, its underground structure is rather well documented.

In this study, we use published and newly collected brine lithium concentration data to train a machine-learning model and create a spatially continuous map of predicted lithium in Smackover Formation brines across southern Arkansas using geologic, geochemical, and temperature explanatory variables.

This analysis pointed out that one site, the Smackover Formation, was much more promising than the others.

出典: Science Advances

リチウム含有量の予測

The AI-driven analysis was able to determine the most important predictive factor leading to the presence of lithium or not:

• 溶存硫化水素（H2S）濃度。
• 塩水サンプルの深さ
• スモックオーバー層上部の標高
• スモックオーバー層の厚さ

出典: Science Advances

Depending on the lowest and highest estimates for brine volume and lithium concentration, the total amount available in the Smackover Formation could be:

• 100万トン（リチウム低、体積低）。
• 1100万トン（リチウム中、体積中）。
• 1100万トン（リチウム高、体積高）。

出典: Science Advances

リチウムの副産物として

Some of these brines have already been brought to the surface, as a result of exploitation for bromine production, or as a byproduct of oil & gas production.

合計で約5,000トン、すなわちスモックオーバー層の利用可能リチウム資源の0.1％未満が、油・ガス・臭素産業の廃棄物流として地上に持ち上げられました。

これは総資源のごく小さな割合ですが、米国の2022年のリチウム消費量を賄うには十分であり、この資源の潜在性を示しています。

And “Big Oil” is looking at the potential to leverage its expertise in drilling in the region, with Exxonによる「リチウム井戸」掘削計画.

直接リチウム抽出（DLE）

新たな第3のリチウム抽出技術

Currently, lithium is produced mostly using two different methods.

The first one is crushing lithium-rich rock, like spodumene, which is the type of lithium Australia produces.

The second is the evaporation of brine using solar energy in vast evaporation ponds. This is a very cost-efficient method, but it also consumes a lot of water, captures only 50% of the available lithium, and causes significant pollution.

A third method is now being developed: direct lithium extraction.

選択的膜

The commonly used lithium concentration methods rely on evaporation and/or mineral concentration. Instead, direct extraction targets the lithium atoms through a selective extraction process. This can be achieved through a few different methods:

• 吸着型DLE：リチウムが専用素材に物理的に吸着される方式。
• イオン交換型DLE：リチウムが陽イオンと交換される方式。
• 溶媒抽出型DLE：有機液体溶媒がリチウムを吸収・溶解し、塩水から分離する方式。

出典: Lithium Harvest

Oilfield brines may be an important lithium resource because these brines occur globally, are otherwise considered a waste product from the oil, gas, and brine industries, and—depending on the viability of direct lithium extraction technologies—would not require a large footprint similar to the evaporative processes used to concentrate basin brines

“機械学習を用いた南アーカンソーのスモックオーバー層塩水におけるリチウム資源の評価”。

リチウムナノ濾過

A new method for direct extraction might also have been discovered by researchers at Monash University (Australia), published in Nature Sustainability under the title “塩湖塩水からの持続可能なリチウム抽出とマグネシウム水酸化物の共同生産”.

彼らはEDTA支援緩やかなナノ濾過（EALNF）を用いてリチウムを抽出しました。この方法はリチウムとマグネシウムを同時に抽出でき、全体的な効率を向上させます。従来、マグネシウムはリチウム抽出の廃棄物と見なされていました。

このプロセスはMg2+の超高除去率（99.85％）と超高速Li+フラックス、そして産業条件下で前例のないLi+/Mg2+分離係数を実現します。

Magnesium is often present in brine and can cause problems for selective extraction of lithium. This has often caused such resources to be ignored in favor of “easier” brines.

“Our technology achieves 90 percent lithium recovery, nearly double the performance of traditional methods, while dramatically reducing the time required for extraction from years to mere weeks.”

It is also less water-consuming than waiting for brine to evaporate in artificial pounds. In fact, it even produces fresh water as a byproduct, instead of consuming it. With a lot of lithium resources in water-poor regions, this could make a difference.

リチウムとバッテリーテクノロジーへの投資

Lithium-ion batteries have already changed the world several times, from allowing people to carry advanced electronics everywhere to powering cars with electricity only.

それらは再び、100％再生可能エネルギーの電力網を実現したり、十分なエネルギー密度に達すれば航空機の電動化を可能にしたりすることで、再び世界を変える可能性があります。

You can invest in battery-related companies through many brokers, and you can find here, on securities.io, our recommendations for the best brokers in the USA, Canada, Australia, the UK, as well as many other countries.

If you are not interested in picking specific battery companies, you can also look into biotech ETFs like Amplify Lithium & Battery Technology ETF (BATT), Global X’s Lithium & Battery Tech ETF (LIT), or the WisdomTree Battery Solutions UCITS ETF (WT ), which will provide a more diversified exposure to capitalize on the growing lithium and battery industry.

Or you can consult our “Top 10 Battery Metals & Renewable Energy Mining Stocks”.

直接リチウム抽出企業

リオ・ティントは鉱業界の巨人（世界で2番目に大きい）で、鉄鉱石採掘を中心に、銅、アルミニウム、金、ウランなどにも強い存在感を持っています。

リオ・ティントは、ギニアのシマンドゥ巨大鉄鉱山プロジェクトやモンゴル史上最大のプロジェクトであるオユ・トルゴイ銅鉱山など、急速に拡大しています。

リオ・ティントは今後5年間で世界の銅供給増加量の25％を占めると予測されています。

最近、リオ・ティントはリチウム採掘部門に大規模に参入し、リチウム大手Arcadium Lithiumを取得しました。Arcadiumは2023年に大手リチウム生産者AllkemとLiventの合併により誕生し、世界で3番目に大きいリチウム生産者となっています。

出典: Arcadium

The merger created a company in all lithium production and processing steps. Arcadium has expansion plans in place to more than double capacity by the end of 2028

Arcadium イノベーション

DLE

Regarding this acquisition, what has been described as “Rio Tinto’s real prize (RIO ) ” is Arcadium’s direct lithium extraction (DLE) technology. Arcadium has actually been working on DLE since 1996, in combination with evaporation pounds, and recently made significant progress in making it commercially viable as a stand-alone extraction method.

Notably, Livent acquired  ILiAD Technologies in 2023.

“ILiAD Technology Platform combines a superior lithium selective adsorbent with continuous countercurrent bed processing”

“Livent is the world’s foremost practitioner and largest user of DLE-based production processes, and we are thrilled that they have recognized the advantages that ILiAD brings to the future of DLE.

It seems that the long-term expertise of Arcadium with DLE, and the “vast range of lithium laden brines under a wide variety of conditions” of ILiAD were a prime reason for Rio Tinto’s decision to acquire Arcadium, on top of its low valuation due to the cyclical nature of lithium markets.

リチウムフォイル

Arcadium also developed LIOVIX, a form of printable lithium foil that could be used to boost battery performances, reduce manufacturing costs, and reduce lithium use.

出典: Arcadium

リオ・ティントのグリーン・プロファイル

Arcadium’s acquisition firmly put Rio Tinto in the camp of mining industry innovators after its innovation in copper extraction through its venture Nuton. Nuton’s new technology allows for a much higher rate of copper recovery from mined ore.

Rio Tinto’s aluminum production is low-carbon, thanks to hydropower being used to refine bauxite into alumina and then aluminum.

Rio Tinto also invested in other lithium projects, recently acquiring the Ricon project in Argentina and the controversial Jadar lithium project in Serbia (potentially the largest lithium project in Europe).

Due to its recent acquisitions and new projects, Rio Tinto should increasingly be seen as an iron miner at the core, with an increasingly green profile and strong growth in all the metals required by the energy transition, especially copper, low-carbon aluminum, and lithium.

研究参考文献：

^{1. Knierim, K. J., et al. (2024). 機械学習を用いた南アーカンソーのスモックオーバー層塩水におけるリチウム資源の評価. Science Advances, 10, Article adp8149. https://doi.org/10.1126/sciadv.adp8149}