PNNL patents method for extracting lithium from water


Alchemists of old sought to convert low value lead into high value gold.

A solution to this puzzle remains elusive, but researchers at Pacific Northwest National Laboratory have discovered something more applicable to today’s challenges.

The lab has patented a revolutionary new method for extracting lithium from water.

There’s a lot more suspended in H2O than just loosely bound hydrogen and oxygen.

Take, for example, the mining effluent produced by oil and gas drilling. In the resulting wastewater brine generated during hydraulic fracturing (fracking) and other processes, sediments from deep within the earth are brought to the surface along with the water used to aid in the drilling process.

Among these materials are traces of high-value rare earth metals, such as lithium, which are sought after by manufacturers of semiconductors, wind turbines, electric vehicle (EV) batteries and lithium-ion batteries. rechargeable batteries in phones and other everyday electronics.

Although these elements were known to be present in these brines produced in drilling, geothermal and desalination plants, before the breakthrough of PNNL, the lingering question was how to isolate them in a way that was both practical and economical. feasible.

The secret sauce

PNNL’s newly discovered method is based on a simple concept commonly seen in a classic elementary school science experiment: using a magnet to attract iron filings, according to Karyn Hede, Media Relations Advisor and Science Communicator at PNNL. .

Instead, in this case, a specialized magnet is designed to attract the lithium.

Jian Liu, a senior chemical engineer and one of the project’s lead researchers, explained that although it was known that lithium could be extracted using a magnet, the question was how to isolate it from other magnetically attractive elements also present in brine.

Magnets are metals that indiscriminately attract other magnetic metals, making it difficult to extract only lithium.

The PNNL research team – Pete McGrail, laboratory researcher and expert in rare earth metal recovery technology, Praveen Thallapally, principal investigator, and researchers Jian Liu, Satish Nune and Yongsoon Shin – realized they had to develop some sort of filter that would select for lithium.

The team’s many years of joint experience with adsorbents – materials that cause atoms, ions or molecules in solution to adhere to their surface rather than absorb them, which would make them more difficult to isolate – provided the answer to the riddle.

Liu explained that his team “grows” a refined lithium selective adsorbent – also called a ligand – on top of a black magnetite (iron oxide) magnet. Thus, only lithium can bind to the adsorbent covering the magnet.

“The adsorbent is probably more valuable than rare earth metals,” Liu said.

This led the team to another hurdle: “You have to be able to reuse (the adsorbent) or you sacrifice one valuable material for another,” he said.

Fortunately, the magnetic nanoparticles used to isolate and extract lithium can be recharged and reused.

As McGrail explained in a PNNL press release, “Our nanotechnology process allows us to miniaturize everything and removes the need for massive ion exchange separators required in other processes.”

Instead, the brine water is passed through an extraction system, which houses the extraction nanoparticles.

“It’s quite simple. Within minutes, virtually all of the lithium has been pulled out of solution by molecular collisions with our sorbent and can then be removed with a magnet where it is easily collected and purified,” McGrail said.

The water is then returned to its source, if not unchanged.

Conventional methods using evaporation ponds can take months or even years to isolate the lithium and have far more negative impacts on the environment.

“I think this will be a technique that can be applied to a variety of different metals as long as you have a selective adsorbent,” Liu said. Other rare earth metals in high demand that could be targeted next are cesium, nickel and cobalt.

Industrial and environmental implications

The breakthrough should bring much-needed relief to a strained industry.

Due to the exponential increase in demand for rare earth metals in existing and emerging technologies, expensive and energy-intensive extraction methods are pushed to their limits to meet this demand.

Green technologies such as electric vehicles, for example, have reduced the cost of batteries since their inception, striving to achieve overall cost parity with their traditional gasoline and diesel counterparts.

However, in recent years, this downward price trend has started to level off, hooked on the cost of producing key ingredients: rare earth metals.

Currently, almost no lithium is produced in the United States.

The majority is produced in South America, primarily in Argentina and Chile, along with operations in Australia and China.

According to the Department of Energy, imports represent 100% of US supply for 14 of the 35 critical materials and more than half for 17 others.

Hede noted that many of these international sources are in high-conflict regions.

By 2028, the global lithium market is expected to reach $8.2 billion.

“The cost of lithium has increased fourfold in the past year alone,” Liu said.

With this breakthrough, the potential for the US market is great.

PNNL scientists have estimated that if 25% of lithium was collected from wastewater generated by oil and natural gas extraction, that alone would equal the current annual global production.

The additional revenue stream for these metal-rich brine producers could in turn reduce the cost of power generation.

“Why that’s important,” Liu said, “is that we’re trying to come up with a technology that can boost lithium production…so that the price of lithium batteries can hold up or even come down, in addition nickel, cobalt and other metals… We can help modernize the electric car industry and reduce greenhouse gas emissions. We are very hopeful that this will solve many great challenges for our community.

Scale it

Due to Covid-19 and some technical issues along the way, Hede said the concept is still in the lab phase to test different adsorbent ligands.

There is a pilot project planned in the pipeline, co-funded by the DOE’s Office of Fossil Energy.

Another will partner with a renewable energy investment firm, Moselle Technologies, which has licensed the technology and plans to pilot it at several of its sites.

A collaboration with Mosel and mineral recovery company Geo40 is also actively exploring routes to extract cesium and antimony from brines at a geothermal power plant in New Zealand.

Other business partners – Enerplus Corp., Prairie Lithium Corp., Enertopia Corp. and Dajin Lithium Corp. – with lithium resources in Nevada and Canada are on board to study the potential application of the extraction technology at their sites.

Established in 1965, PNNL is managed by Battelle for the DOE’s Office of Science with the stated goal of advancing scientific knowledge and addressing the challenges of sustainable energy and national security.


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