Developing new lithium mining processes is necessary to meet the need for rechargeable batteries in electric vehicles (EVs) that will help address climate change, not to mention the lithium used in all the rechargeable batteries for cellphones, laptops, and other digital devices. However, there’s an environmental tradeoff when it comes to lithium extraction. Mining processes used traditionally to extricate lithium from other minerals or underground water sources can cause significant environmental damage.
With the demand for lithium increasing tenfold, or more, in the coming decades due to the increasing use of EVs for transport, it’s important for mining companies to look at more innovative extraction methods. While there are plentiful quantities globally, lithium mining processes traditionally require vast amounts of water and often significant earth removal. Regarding lithium, mining processes can often threaten communities in drought-prone areas and disturb fragile ecosystems. Due to these challenges, companies in the United States and globally are constantly seeking to improve methods for extracting the minerals to prevent damage to communities and their local environment.
Conventional and Innovative Lithium Mining Processes
There are two primary ways in which lithium is mined. The most common method involves extracting lithium from brine contained in underground reservoirs. The second most common way of extracting lithium looks like a mining process used to extract other minerals. A third lithium mining process, which is getting increasing attention, involves directly extracting it from saltwater. Additionally, producers continue to investigate other lithium mining processes to produce enough of it to keep modern industries that utilize the mineral from running low.
Conventional Lithium Brine Extraction
For most commercially available lithium, mining processes involve the extraction from brine reservoirs underground. Called salars in Spanish, they essentially process lithium salts from these waters in much the same way as sodium-based salts are removed from saltwater. Most of these salars are located in high elevations in the Andes Mountains, where Argentinian, Chilean, and Bolivian borders meet, along with China.
This method for recovering lithium from brine is basic, though time-consuming. It involves pumping the salty brine to the surface into evaporation ponds, where the water evaporates over many months, even years until only the salts remain, which contain high concentrations of lithium. Mining processes utilizing this evaporation process add hydrated lime, also known as calcium hydroxide, to the brine to hurry the removal of elements like calcium boron and magnesium hydroxide salts, which aren’t useful to lithium producers.
Once concentrations of lithium reach a certain point, lithium production follows these steps:
- Brine is pumped into recovery facility.
- Brine is refined to eliminate undesirable elements and impurities.
- Refined brine is treated with chemicals to extract desired minerals and byproducts.
- Filtered to get rid of any unwanted leftover solids.
- Treated with sodium carbonate, known also as soda ash, to remove lithium carbonate.
- Lithium carbonate is then washed and dried into end product.
This lithium mining process also tends to consume large quantities of fresh water. This water is largely drawn from aquifers, rivers, wells, or other water sources used for drinking or irrigation. As the highest concentrations of lithium deposits from brine reservoirs are in arid areas, this means less potable water for nearby communities.
Hard Rock Lithium Mining Process
Like other minerals, lithium mining can instead involve moving vast amounts of rock, soil, and dirt. This can disrupt both animal and plant life in nearby areas. This lithium mining process is also more energy-intensive and complex than extracting the metal from brine. Though more than 145 minerals contain lithium, only five are used to extract lithium commercially. Mining processes like these look for concentrations of spodumene, petalite, lepidolite, eucryptite, and amblygonite from which to extract lithium. The most common of these minerals is spodumene, for which Australia accounts for the most production, with Brazil, China, Portugal, and southern Africa engaging in less significant mineral mining. Additionally, by 2025, new hard rock lithium mining will occur in Finland and North America.
The hard rock lithium mining process uses the following steps:
- After the ore is mined, it’s crushed.
- The crushed mineral is then cooked in a dry heat at 2012°F (1100°C).
- Once cooled to 140°F (65°C), it’s re-milled and cooked again at 482°F (250°C), treated with sulfuric acid in a process called acid leaching.
- During acid leaching, lithium ions replace the hydrogen in the sulfuric acid, producing lithium sulfate along with insoluble residue.
- As with brine’s lithium extraction, lime is added to remove the magnesium.
- Sodium carbonate is then used to filter out lithium carbonate to create a purified solution.
During the acid-leaching process, a lime slurry may sometimes be used to adjust pH and neutralize excess acid.
Other Potential Lithium Mining Processes & Sources
Though both the above conventional lithium mining processes create environmental and water issues wherever they’re used, mining companies can mitigate these with new technological advances. Additionally, a new lithium mining process utilizes a technique for direct extraction of the metal and requires very little water. Other methods involve using geothermal energy or reusable beads to extricate the dissolved metal from brine reservoirs.
In the United States, the only mined lithium production done at a commercial level comes from an operation in Nevada that extracts the metal dissolved in brine reservoirs. Additionally, Ohio hosts one of the largest lithium battery recycling plants in North America, with plans to expand its facility there in the works. Pressure continues to grow to increase US lithium production, especially after the 2020 pandemic showed the effects of disrupted supply chains. For this reason, it’s likely that domestic lithium mining processing will become a priority.
Direct Lithium Extraction
This method involves absorbing lithium from saltwater sources using a material or bead that supports ion exchange, after which it’s washed with hydrochloric acid. Direct lithium extraction produces a diluted solution containing lithium chloride, along with impurities, and works well for areas where evaporation ponds are unsuitable. This lithium mining process offers opportunities in areas where there are geothermal brine pools, such as from the Salton Sea in California and water used in shale gas fracking in Texas. A few different methods are being looked at to remove impurities. This includes acid leaching with both hydrochloric and sulfuric acids, along with the use of calcium carbonate to neutralize waste before releasing the water back into the environment.
Geothermal Brine Extraction
Using geothermal energy to extract the metal is a lithium mining process that’s nearing commercial stages of development. This technique also has the unique side effect of producing electricity. It’s very similar to the most popular method of using brine reservoirs to produce lithium, though it uses hot salty water, also known as geothermal brine. In short, it involves pumping this naturally heated brine to the surface, where it generates electricity by turning a turbine.
Benefits from this geothermal lithium mining process include:
- Environmentally friendly energy production
- Nearly carbon-free extraction method.
- Not dependent on weather
- Small physical footprint
Currently, energy companies are using super-heated underground brine pools by the Salton Sea in California to produce electricity. This brine is pumped from thousands of feet below the surface to move pressurized water with temperatures around 500°F (260°C) through pipes until it loses pressure and becomes steam. This steam turns turbines to generate electricity before it’s reinjected back into the rock formation from which it was pumped, thus making the resource renewable.
There are three main steps to this lithium extraction process:
- Heavy metals are removed from the brine within a shipping container.
- An absorbent soaks up the lithium while keeping other minerals dissolved within the brine; this is paired with equipment that makes this process much more efficient, reducing the time it takes to process.
- Lithium is currently sent to another facility, where it’s converted to an end product sufficiently pure for batteries, though this could eventually be done onsite.
This process takes minutes or hours to concentrate and purify the lithium, which can take as much as 18 months using the methods used in South America.
Ion Exchange Beads
This lithium mining process involves making porous ion exchange beads that are made by coalescing and blending particles that create a reverse exchange between hydrogen and lithium, along with filler and matrix materials. The mixing of these porous beads forms a solution, with an option of heating the beads. This filler material is then removed to create ion exchange beads. This method treats low-concentration solutions containing lithium salts that also contain high amounts of heavy metals, alkaline earth, and alkali. These treatments can be used in conjunction with geothermal lithium extraction processes to obtain even higher amounts of lithium after the brine has gone through the absorbent material.
Production During & After the Lithium Mining Process
Heyl Patterson Thermal Processing makes a variety of dryers and coolers used for bulk powders and solids that can be utilized for any of the lithium mining processes described above. Our company has been building customized dryers and coolers since the 19th century, continuously focusing on efficiency and innovation.
These include Heyl Patterson’s:
- Rotary dryers and coolers used as mainstays within the thermal processing industry and are capable of handling many different kinds of materials, from liquid sludges to hardened minerals; our rotary dryers and coolers can additionally be customized for air velocity, beginning and finishing requirements for moisture, holding times and temperature parameters for materials.
- Fluid bed dryers and coolers are among the largest globally, which are capable of gently handling materials and high heat transfer rates; able to be adjusted to work best with specific materials, we offer three main varieties: the circular, trough or vibrating types.
- Flash dryers work well for materials that are very finely ground, sensitive to temperatures, or those with high moisture content; our flash dryers leave the end product completely dry and undegraded, with drying times for particles proportional to their dimensions and mass.
- Calciners use a thermal processing technique called calcination to carry out two separate steps, decrepitation and acid roasting. These, in turn, help to produce lithium carbonate and lithium hydroxide.
To learn more about how we can assist with your lithium mining processing needs, we invite you to contact our expert team today.