Greener lithium mining: Lithium is crucial for greening transportation and energy networks. Let’s make mining it greener, too.

Materials made from the soft, silvery-white metal such as lithium carbonate and lithium hydroxide are essential ingredients for the cathode and electrolyte of lithium-ion batteries used in electric vehicles (EVs) and energy storage applications, ranging from residential systems of a few kilowatt-hours to multi-megawatt electric grid technologies.

Demand for lithium is set to soar as auto manufacturers move toward EVs, with many countries including Canada, France, the Netherlands, Norway, Sweden, and the U.K., announcing a phase-out of internal combustion engine cars.

According to a World Bank report, “Minerals for Climate Action: The Mineral intensity of the Clean Energy Transition,” five times more lithium than is mined currently will be needed by 2050 to meet the expected demand for clean energy technologies.

Yet despite lithium’s importance to a greener energy future, there are considerable environmental impacts from obtaining lithium using conventional extraction methods. These include carbon emissions, water loss, ground destabilisation, ecosystem degradation, biodiversity loss, contaminated soil, and toxic waste.

Presently, most lithium comes from spodumene (hard silicate mineral) or underground brine reservoirs. Extracting lithium from these resources generally involves two methods.

Traditional hard rock mining can be expensive and requires a lot of energy that releases significant amounts of greenhouse gas emissions, consumes large volumes of water, and produces toxic waste streams typically containing salts, surfactants, organic extractants, and solvents.

Five of the world’s largest spodumene mines are in Western Australia, including the Greenbushes mine, the world’s highest-grade lithium mine, operated by Talison Lithium Australia .

The second method involves pumping salty, mineral-rich brines to the surface from below dried salt flats (called salars) and then leaving it to evaporate, which creates a mixture of manganese, potassium, borax, and lithium salts. The process can take between 12 to 18 months, with the lithium extracted as lithium carbonate. This can be converted into lithium hydroxide through an additional chemical process. Although generally more economical than hard rock mining, the brine process uses vast amounts of water, is chemically intensive, employing a series of solvents and reagents to isolate the lithium from impurities like magnesium, generates large volumes of waste, and is extremely slow.

Around two-thirds of global lithium production currently comes from brines in an area known as the lithium triangle – an arid region of the Andes mountains that encompasses parts of Argentina, Bolivia, and Chile. The area includes the 3,000-sq.-km Salar de Atacama in Chile, which is estimated to have lithium resources of 6.3 million tonnes. Two of the world’s leading lithium producers, SQMand Albemarle, operate there. (It is estimated that mining activities in the Salar de Atacama consume about 65% of the region’s water supply.)

Geothermal lithium brines containing hot, concentrated saline solutions and advances in technologies such as direct lithium extraction (DLE) and nanotechnology-based lithium extraction solutions, however, promise a lower-cost and more environmentally sustainable supply of lithium.

Geothermal lithium brines

While geothermal lithium brines currently make up only about 3% of known global lithium resources, extracting lithium from geothermal waters has a minuscule environmental footprint compared to hard rock mining and salars.

The Salton Sea in Southern California is the largest-known geothermal lithium brine resource globally. According to David Hochschild, chair of the California Energy Commission, the area “has the potential to supply 40% of global lithium demand … [and] will allow for the greenest way to recover lithium that exists in the world.”

Working in the Salton Sea geothermal field in Imperial Valley is Controlled Thermal Resources. The privately-held Australian company is advancing its Hell’s Kitchen lithium and power project, which will combine DLE with renewable geothermal energy to produce an environmentally sustainable source of lithium and renewably generated electricity.

Rod Colwell, Controlled Thermal Resource’s CEO, says the project “will not only provide a significant supply of battery grade lithium to meet the expected increase in demand, but the project also offers an environmentally sustainable source of lithium when compared to pit mining and evaporation ponds.”

At full production, the Salton Sea project will have a capacity of 300,000 tonnes of lithium carbonate per year and a power output of 1,100 MW of clean geothermal energy.

According to Colwell, Hell’s Kitchen will use a closed-loop system that first pumps hot brine (at over 400°C from below the ground and then separates it into steam – a portion of which is used to drive a turbine to produce electricity – and concentrated brine. The brine and remaining steam react to produce lithium chloride for conversion to lithium carbonate or lithium hydroxide, with the spent steam and brine returned to the ground.

“The process is much more cost-effective than conventional lithium extraction, produces high quality lithium products within hours with virtually zero carbon emissions, doesn’t use any solvents, leaves no tailings, and produces 100% renewably generated electricity that can be exported to the grid. Hell’s Kitchen will have a minimal physical footprint too and will eliminate the need for offshore processing of lithium,” Colwell added.

The project has a total inferred resource of 15 million tonnes of lithium carbonate. Colwell says the first 50 MW of baseload power will be delivered in late 2023 and the first 20,000 tonnes of lithium hydroxide in the first quarter of 2024.

In 2020, Controlled Thermal Resources signed a power purchase agreement with Imperial Irrigation District to supply 40 MW of renewable power over 25 years. Last July, the company also formed a strategic investment and commercial collaboration with General Motors to provide the U.S. auto manufacturer with battery grade lithium carbonate and lithium hydroxide for its EVs.

“We are also in talks with other U.S. carmakers and OEMs that are seeking to secure a domestic supply of sustainably sourced lithium products,” Colwell said.

Warren Buffet’s Berkshire Hathaway Energy also plans to extract lithium from brine at its geothermal operations in the Salton Sea.

In Europe, German-Australian firm Vulcan Energy Resources is also developing a combined geothermal lithium brine and geothermal power project.

The company is advancing its Zero Carbon lithium project in Germany’s Upper Rhine Valley – considered the largest lithium resource in Europe – and plans to provide lithium products for the European EV market.

Using a similar approach to that employed by Controlled Thermal Resource, Vulcan plans to produce “a unique, premium, battery quality [lithium] hydroxide product for EVs, with a zero-carbon footprint,” says Francis Wedin, Vulcan’s co-founder and CEO, in an email.

“The Zero Carbon lithium project will have the highest environmental performance, with the lowest impacts of any lithium project anywhere in the world.”

According to an analysis by raw materials experts Minviro for Vulcan, hard rock mining releases 15 tonnes of carbon dioxide (CO2) per tonne of lithium hydroxide at a cost of US$6,855 per tonne, and five tonnes of CO2 per tonne of lithium hydroxide at US$5,872 per tonne from brine reservoirs. In contrast, extracting lithium from geothermal brines releases zero CO2 emissions at only US$3,140 per tonne.

It’s a similar story for water consumption. Minviro estimates that for every tonne of lithium hydroxide extracted by hard rock mining, 170 m3 of water are consumed, which and rises to 469 m3 per tonne from brines. Lithium extracted from geothermal brines at the Zero Carbon project consume only 80 m3 of water per tonne.

In addition to a smaller carbon and water footprint, extracting lithium from the project will also have a much lower physical footprint compared to hard rock mining or extraction from salars, reports Minviro.

Their analysis showed that 464 m2 of land is needed to produce one tonne of lithium hydroxide from hard rock mining and a whopping 3,124 m2 per tonne for salars. This figure drops to only 6.0 m2 land per tonne from the Zero Carbon project.

Minviro also conducted a life cycle assessment for lithium produced from the project. The study showed that it would produce lithium monohydrate with a carbon footprint of negative 2.9 tonnes of CO2 per tonne.

Wedin says that this negative CO2 emission intensity “is a product of the significant impact of the [carbon] offset generated by renewable geothermal energy production process and the use of geothermal heat to drive lithium processing. This is underpinned by our industry leading move to strictly exclude fossil fuels as an energy source for Vulcan’s planned operations.”

This year, the company plans to complete Phase 1 of a definitive feasibility study and is targeting the first commercial production in 2024, with 15,000 tonnes of lithium hydroxide per year. In addition, a planned second stage of expansion, slated for 2025, would add 25,000 tonnes of capacity per year for a total annual production of 40,000 tonnes of battery grade lithium hydroxide.

“Our binding, definitive lithium offtake agreements with Volkswagen Group, Stellantis, Umicore and Renault Group, and most recently with LG Energy Solution, ensures we have a diversified mix of off-takers from the cathode, battery, and automotive sectors,” Wedin said.

Cornish Lithium is also working on plans to extract lithium from geothermal brines. The company said that it has found “globally significant” lithium grades in deep geothermal waters at its United Downs deep geothermal power project near Redruth in Cornwall, England.

Nanotechnology

Spun-out of the University of Calgary in 2019, Litus Energy and Environmental Solutions has developed a nanotechnology-based lithium extraction technology to extract lithium from salars and geothermal brines.

The patent-pending LiNC technology uses a nanotechnology composite material “that has an extremely high selectivity and absorption rate for lithium ions in brines solutions even in the presence of high concentrations of competing ions such as sodium, magnesium, and calcium,” says Ghada Nafie, co-founder and CEO of Litus.

“This extreme selectivity allows for much higher lithium recovery, with recoveries up to 95%. The process is also very rapid and eliminates the need for several steps used in conventional evaporation ponds, significantly reducing the cost of extracting lithium from brines.”

According to Nafie, the LiNC technology is highly energy efficient and has a small carbon footprint, leaves the brine virtually unchanged, uses significantly fewer chemical reagents, and generates minimal waste. “The technology would extract more lithium from brine sources more efficiently, more sustainably, and more economically than conventional methods.”

Litus has partnered with Canadian lithium brine explorer HeliosX Lithium & Technologies, formerly Dajin Lithium. HelixosX is evaluating the LiNC technology as a potential DLE solution for its lithium brine assets in Alberta, which includes over 125,453 hectares of prospective lithium rights. HelixosX is conducting a prefeasibility design for a pilot facility in Alberta in 2023.

Another Calgary-based tech start-up Summit Nanotech is developing its denaLi technology that also uses nanotechnology to improve lithium extraction from brines.

(By Carl Williams)