Lithium mining is sort of a fashionable gold rush. The ingredient is the primary ingredient in batteries powering smartphones, electrical vehicles, and even AI. International demand is surging. Elevated manufacturing might information the world towards a extra sustainable power future.
However satirically, present extraction strategies offset a few of these beneficial properties. Lithium mining entails separating the ingredient from brines utilizing poisonous chemical substances, a course of that additionally pumps out carbon dioxide. This, alongside huge water and power prices—resulting from excessive temperature necessities—has confined mining to a handful of nations.
To deal with these drawbacks, scientists on the Massachusetts Institute of Know-how have now developed a low-cost, low-temperature, greener course of counting on an considerable useful resource: Laborious rock. Though rocks containing lithium cowl massive elements of the US, Europe, and Africa, extracting it from them is difficult.
Whereas renovating his toilet, research writer But-Ming Chiang realized a chemical in glass etching cream—which makes glass translucent—might eat away at lithium-rich rocks. His group then designed a recyclable course of to extract lithium in addition to two elements used to make greener cement and different supplies.
“You’ve heard of nose-to-tail consuming?” stated Chiang in a press launch. “We check with this as nose-to-tail mining.”
Not like earlier strategies, the method runs at temperatures under the boiling level of water. All liquid chemical substances are virtually recyclable and may be reused in a number of rounds of extraction.
“This might set up a low-carbon different to laborious rock refining, addressing each the surging demand for lithium and the carbon footprint that undermines the sustainability of the power transition that lithium is supposed to allow,” wrote Gang San Lee and Karthish Manthiram on the California Institute of Know-how, who weren’t concerned within the research.
A Rock and a Laborious Place
The Earth’s crust teems with lithium. Getting it out is the laborious half.
At the moment, many mining operations depend on brine that naturally leaches lithium over millennia. Later steps purify the lithium right into a battery-ready product. The method depends on massive evaporation swimming pools and is proscribed to some international locations, making the useful resource scarce.
Lithium might, alternatively, be harvested from stable rocks. One ore, spodumene, is full of lithium, roughly 1.5 % by weight. However liberating it has been a troublesome nut to crack.
Historically, miners crush rocks and take away chunks that don’t include lithium. The rocks are then blasted at temperatures as excessive as 1,100 levels Celsius (2,012 levels Fahrenheit) and showered in a cocktail of harmful chemical substances. The method spews liquid waste into the atmosphere and releases 20 tons of carbon for every ton of lithium.
Researchers are engaged on extra temperate strategies.
One among these is known as ball milling. Ore is rotated in a container stuffed with laborious balls that mechanically grind the stone right into a wonderful energy. It’s like utilizing a mortar and pestle as an alternative of a blender. However the course of takes longer, and lithium is misplaced alongside the way in which, leading to decrease yields. One other methodology, referred to as electrochemical leaching, refines the ore at room temperature. However researchers have had blended success with the method, and it’s robust to scale up. It additionally produces in quite a lot of waste rock that might, in principle, be harvested for different makes use of as an alternative being discarded.
Triple Menace
The brand new methodology popped into Chiang’s thoughts as he was brainstorming methods to interrupt aside spodumene, a lithium-rich ore with excessive quantities of silica—the primary ingredient in glass.
Dissolving silica to get to lithium requires hydrofluoric acid, a extremely poisonous chemical. However glass etching cream additionally eats away at silica with ammonium fluoride. Tubes of the gentle acid can be found in dwelling enchancment shops, and it really works at room temperature. Why not give it a attempt?
By mixing ammonium fluoride with water, the group confirmed they might fully dissolve spodumene at temperatures under 100 levels Celsius with out releasing poisonous fumes. They solely wanted to constantly stir the ore in a easy plastic tank. The method yielded a number of forms of lithium salt with 99 % purity. In early experiments, extraction took a number of days, however the group has since lower the time to underneath 12 hours.
“Dissolving silica is the laborious half in mining,” stated research writer Benjamin Mowbray. “The subsequent query was how can we apply it to impactful mineral processing issues?”
Together with lithium, spodumene is jam-packed with two often discarded elements: Alumina, which after smelting makes aluminum, and silica, which may be immediately used as a sustainable ingredient in greener cement. The brand new course of can separate out each supplies, and the group vetted the ensuing merchandise, together with energy testing cubes of fabricated cement.
“First our aim was to supply these merchandise, then there have been further steps of characterizing their purity and properties and ensuring our merchandise met the specs for goal markets,” stated Mowbray.
“If any product didn’t meet the goal specs, you’d find yourself with a waste stream.”
With a couple of chemical tweaks, the group confirmed the acid could possibly be regenerated and reused at the very least 5 occasions. The group efficiently processed 17 spodumene ores sourced from around the globe, suggesting the tactic could possibly be broadly relevant.
They’ve additionally spun the work right into a startup, Rock Zero, and intention to scale it. If the acid may be recycled with near-perfect effectivity, the group estimates the method would lower prices over 40 % in comparison with typical hard-rock extraction, making it aggressive with brine operations.
Its simplicity might additionally reshape the place lithium will get produced. In 2024, roughly 74 % of worldwide lithium output got here from simply three international locations: China, Australia, and Chile. By eliminating the necessity for excessive warmth and large waste-treatment vegetation, the method could possibly be simpler to implement, particularly in international locations wealthy in spodumene however missing the capital for infrastructure.
That opens the door to a community of smaller refineries constructed nearer to the mines themselves, lowering transportation prices and supply-chain bottlenecks. As a result of the method can also be far much less power intensive, it could possibly be powered by photo voltaic and wind, additional shrinking its environmental affect.
The expertise is also tailored to recuperate different beneficial metals hidden inside mineral ores. One candidate is beryllium, a light-weight however extraordinarily stiff and secure metallic utilized in satellites and the James Webb Area Telescope’s mirrors. Present manufacturing processes usually generate poisonous mud and fumes linked to severe lung irritation. A cleaner extraction route might make it safer and cheaper to supply.
As for Rock Zero, going up in opposition to established lithium giants is like David and Goliath. They’ll additionally need to take care of world market volatility and growing competitiveness of sodium-ion batteries and different different battery chemistries.
However the group is unfazed. “We imagine this method is the lowest-energy, lowest-cost method of getting lithium not solely out of laborious rock, however interval,” stated Chiang. “That’s what’s motivating us to scale this.”
