International Battery Metals Inc. was recently featured on The Innovation Platform, highlighting IBAT’s direct lithium extraction technology, which demonstrates superior performance over traditional extraction methods.
The market for lithium is growing rapidly, as demand for the metal continues to surge in batteries for electric vehicles and energy storage. In order to meet this demand, it's important to have a robust and efficient extraction process that can provide high-quality lithium products. In this blog post, we'll take a closer look at traditional lithium extraction methods and how IBAT's direct lithium extraction technology sets us apart from the competition.
- Intricacies Of Direct Lithium Extraction Technology
- Complications With Ion Extraction
- Why Do So Many Direct Lithium Extraction Processes Fail?
- IBAT's Direct Lithium Extraction Technology
Intricacies Of Direct Lithium Extraction Technology
Direct lithium extraction technology removes lithium and associated anions from a brine solution and transfers it into a different medium, such as water, for further processing to final products.
Conceptually, DLE is straightforward. One utilizes an extractant that will selectively remove lithium ions from a complex solution. The extractant is exposed to a lithium-bearing brine until a state of equilibrium is achieved. Depending on the ion uptake mechanism associated with a specific extractant, multiple competing ions can be found on the same extractant particle.
The goal is to extract lithium and leave the other cations behind. For economic lithium extraction to occur, the chosen extractant must present a situation where the lithium association with extraction sites is thermodynamically strongly preferred over other cations in the solution. After reaching ionic equilibrium, the exchange sites are regenerated. However, what will the lithium to non-lithium cation ratio, [Li]/[Na, K, Ca, Mg, Zn, Mn, etc.] be? This relationship defines the extraction efficiency and the lithium product purity of the process.
Complications With Ion Extraction
Natural brines vary from resource to resource and even within the same resource. In addition to lithium, oilfield brines in North America can contain very high levels of calcium, magnesium, iron, and silica. Geothermal brines in Southern California contain sodium, potassium, manganese, zinc, magnesium, calcium, iron, and silica.
Location is another issue. Andean brines are often in very remote locations with limited access to critical support systems such as labor, electricity, natural gas, or fresh water. In fact, most resource locations will typically have one or more adverse issues.
Total salt concentrations are typically very high, but lithium concentrations are low. In some cases, such as Chilean, Argentine, or oilfield brines in the United States, total salt concentrations can exceed 350,000 mg/kg (parts per million), or 35%wt. In these brines, sodium concentrations can exceed 100,000 mg/kg.
Correspondingly, target ion concentrations are very low. For instance, a commercial brine from the Salar Atacama typically presents lithium concentrations that range from 1000 to 2000 mg/kg. Some oilfield brines in Alberta may contain only 50 mg/kg to about 90 mg/kg.
Furthermore, extraction efficiency is higher with greater lithium concentrations. Thus, with a 50 mg/kg brine, we will likely see lower lithium recovery even with the very high flow rates. Thus, lithium concentration matters.
Generally, lithium extractants are quite sensitive to competing ions that are found in the brine. This is a particularly thorny problem with ion-exchange-based extractants.
Why Do So Many Direct Lithium Extraction Processes Fail?
Numerous companies have proposed and are working on various schemes designed to extract lithium from brines. Except for MGX’s failed efforts to thermally evaporate diluted Alberta brine using crystallizers to recover pure lithium chloride and millions of tons per year of unusable waste salt, DLE start-ups are focused on identifying and developing processes for the selective removal of lithium from a source brine.
In their quests, these companies have employed numerous materials to selectively recover lithium, including solvent extraction, membrane separations, polymeric- and inorganic-based ion exchange, chelation and coordination schemes, combination exchangers, adsorption and absorption materials.
The Ion Exchange Concept
The most common class of commercial extractants is ion exchange resin. These materials are employed predominantly in water purification applications. They are also utilized to perform various tasks in the chemical industry. They are polymer beads produced as polymer ‘gel’ resin or open networked polymer resin, called macro reticular resin. Polymer ion exchange resins are typically called IX Resin. Ion exchangers can also be based on inorganic materials such as zeolites or insoluble metal salts that have specific functionalities allowing charge-based association with ions.
Once the resin is at equilibrium with the source brine, it must be regenerated with strong acid. This step is followed by a strong base to restore the resin to its initial state. The total molar amount of acid and base will be equivalent to the number of ions exchanged onto the resin plus any waste in the operation. This regeneration step creates significant quantities of waste salt solution. Additionally, the resulting regeneration product solution containing lithium will be acidic, and it must also be neutralized, creating even more waste salt solution.
Thus, each ion exchange cycle is burdened by the cost of large quantities of acid and base plus correspondingly large amounts of water. Additionally, process engineers must remember that all of this waste salt must go somewhere. Therefore, there is a significant environmental challenge associated with this regeneration operation.
Unfortunately, for ion exchange processes, unless there is a ‘magical’ ion exchange material that can recover very high percentages of lithium in one pass, the story is worse. The next step is to run the regeneration solution from the previous step through another ion exchange column to enhance the lithium concentration on the resin.
This multistep process must be repeated numerous times to reach a reasonable lithium concentration in the working solution. The bottom line is that, unless the IX system demonstrates stunning selectivity for lithium, the entire process becomes a giant Rube Goldberg nightmare that will demonstrate poor economics with serious environmental issues.
The Chelation and Coordination Method
Other DLE groups are working with chelation and coordination systems. Most of these approaches are associated with IX, described above. Therefore, they are also wedded to acid-base regeneration cycles. Most of these processes have essentially the same problems as straight IX. A frustrating truth associated with chelation and coordination systems is that they work very well on transition metal ions such as cobalt, copper, nickel, and the like. However, these ions are enormous when compared with a lithium ion. These transition metals have large, expanded electron orbitals that easily associate with coordinating functionalities. The cobalt cation, Co++ has 25 electrons while lithium, Li+ has only two electrons. Again, without some type of special situation, lithium ions are unreachable.
The Liquid Extraction Method
Liquid extraction materials are typically immiscible with water or brine. They function by chelation or ion exchange that takes place at the organic/aqueous interface. During fundamental extractive research, Dow chemist, John Lee, studied the use of certain complex ethers to extract Li via an association mechanism. His systems worked remarkably well in simple NaCl-LiCl systems. However, when adding Ca, Mg, Zn, or Mn to the system, the Li consistently demonstrated very low selectivity. The process was impractical since natural brines will contain at least some of these ions in high concentrations.
The Selective Absorption Method
After working with these materials, IBAT found an ion ‘discriminator’ specific to only Li and could function effectively in a lithium extraction process. The material has a unique crystal structure that allows absorption of lithium ions into its crystal lattice. Other cations cannot enter the crystal lattice.
This characteristic of exclusive lithium uptake into the crystal lattice leads to a selectivity coefficient for lithium over all other cations that is essentially unmeasurable. We have conducted numerous experiments with various brine compositions. We have never observed lattice absorption of any cation other than lithium in each case.
We can routinely reduce the brine lithium concentration in the brine to less than 0.1 mg/kg. Furthermore, upon regeneration of the absorbent, we produced a lithium chloride solution that contains approximately 99% lithium chloride in water. In these operations, regeneration is done with water. No acid or base is necessary. Furthermore, unlike ion exchange systems, the absorbent reached saturation with lithium in one cycle. Thus, the industrial process will cycle between brine for lithium chloride uptake and water for regeneration.
IBAT’s Direct Lithium Extraction Technology
Over the last four years, we have worked to integrate this selective absorbent with a highly efficient modular and mobile extraction plant. First, IBAT’s direct lithium extraction technology takes advantage of an improved version of the ‘selective absorbent’ invented by Dr. John Burba and Dr. Bill Bauman in the early 1990s. As stated above, this absorbent will extract lithium and chloride ions selectively from high salinity brines.
The sorbent rejects other salt components such as sodium, potassium, calcium, magnesium, sulfate, and borate. IBAT’s process operates on a brine-water cycle, unlike virtually all other DLE systems. Lithium chloride is absorbed from the brine and released into the water. Unlike other DLE processes, acid and base are not necessary. Thus, the corresponding waste salts do not exist in the IBAT process. This inherently creates a cleaner operation.
Several other key distinctions exist between IBAT’s patented process and other proposed DLE processes.
1) IBAT’s plant is modular and mobile. This means we can build our entire plant in a fabrication shop in months. Furthermore, IBAT’s modules can be transported and assembled at the resource.
2) IBAT’s plant is designed to produce minimal environmental damage during lithium extraction. We have incorporated several novel technologies that are very environmentally protective.
a) IBAT has developed novel water recovery technology that recycles approximately 98% of the plant’s process water. Solar evaporation projects require enormous quantities of fresh groundwater to support their operations. Due to our water recovery innovations, we will not need local water.
b) With the concurrence of country regulators, IBAT prefers to inject lithium depleted brine back into salars in Chile and Argentina. A great deal of history in the US suggests that this process can be done safely. The advantage is that we will not be polluting vast resource areas with huge quantities of salt waste.
c) Our process is designed to minimize our carbon footprint. We plan to incorporate renewable energy into our plants. We will utilize solar energy. We are also investigating other novel and exciting renewable energy systems that can provide thermal and electrical energy.
IBAT’s novel patented direct lithium extraction technology is based on proven selective absorbent technology and innovative engineering. Our goal is to significantly advance the lithium extraction and production industry ethically.
You can read the full article on the Innovation News Network.
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