Method for removing boron in lithium extraction solutions

Abstract

A method for reducing boron concentration in a lithium-containing aqueous solution, such as a lithium extraction solution, by contacting the lithium-containing solution with granular iron oxide.

Description

[0001] METHOD FOR REMOVING BORON IN LITHIUM EXTRACTION SOLUTIONS

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to use of granular iron oxide in a method for reducing the concentration of boron in lithium-containing water, such as lithium extraction solutions.

[0004] BACKGROUND OF THE INVENTION

[0005] The combination of technological advancements, environmental concerns, government support, and market demand has contributed to the popularity of lithium as a crucial element in the transition to a more sustainable energy future. The rise of electric vehicles (EVs), renewable energy storage systems, portable electronics, and other lithium-ion battery applications has led to a surge in demand for lithium. Lithium-ion batteries are lightweight, have high energy density, and are rechargeable, making them ideal for various applications. They are used to store energy generated from renewable sources like solar and wind power, providing stability to the grid and enabling greater integration of renewables into the energy mix. Electric vehicles powered by lithium-ion batteries produce fewer greenhouse gas emissions compared to traditional internal combustion engine vehicles. This shift toward electric transportation is seen as a key strategy in combating climate change and reducing air pollution. Many governments around the world are implementing policies and incentives to promote the adoption of electric vehicles and renewable energy technologies. These policies include subsidies, tax incentives, and regulations aimed at reducing carbon emissions and promoting sustainable energy solutions, thereby driving the demand for lithium-ion batteries and lithium extraction. The increasing demand for lithium and its critical role in emerging technologies have attracted significant investor interest in lithium mining and extraction projects. This interest has led to investments in exploration, development, and production of lithium resources worldwide.

[0006] There are several methods to extract lithium from natural sources. In brine extraction, lithium-rich brine is pumped to the surface from underground reservoirs, often found in salt flats or salars. The brine is then processed through various techniques, such as evaporation ponds or advanced filtration methods, to isolate and concentrate the lithium. Lithium can also be extracted from hard rock minerals, such as spodumene or petalite. This involves crushing the ore and then subjecting it to processes such as flotation, roasting, and leaching to extract the lithium. Lithium can be found in certain clay deposits. The clay extraction process typically involves acid leaching or other chemical processes to extract the lithium from the clay. Hydrothermal extraction involves using high-temperature water to dissolve lithium from certain minerals. Advances in lithium extraction technologies have made it more efficient and cost-effective to extract lithium from various sources, including brine deposits, hard rock minerals, and clay. These advancements have helped meet the growing demand for lithium while lowering production costs. However, they require improved purification techniques.

[0007] Removing boron from lithium extraction solutions is essential for ensuring the performance, safety, purity, and regulatory compliance of lithium-ion batteries and other lithium-based products used in various industries. Boron contamination can affect the purity of lithium compounds produced from lithium solutions, which can impact the quality and performance of battery materials such as lithium carbonate or lithium hydroxide. Boron impurities in lithium solutions can lead to side reactions during battery operation, which can decrease the battery's energy density, cycle life, and overall performance. Boron impurities can also increase the risk of safety issues in lithium-ion batteries. Boron contamination may lead to the formation of dendrites, which are small, needle-like structures that can cause short circuits and potentially lead to thermal runaway, fires, or explosions in lithium-ion batteries. Removing boron from lithium solutions can improve the efficiency of downstream processes, such as precipitation, crystallization, and purification of lithium compounds. Minimizing boron contamination reduces the need for additional purification steps, saving time and resources in the production process.

[0008] Common anionic ion exchange resins, which may be used for purification in lithium extraction processes, are incapable of removing boron due to their much lower selectivity on boron as compared to other common anion species coexisting in lithium brines, e.g., chloride, sulfate, nitrate and bicarbonate. Special chelating ion exchange resins with an N- methylglucamine functional group are selective to boron and can be effective for this application, but these resins are expensive, generally with lower operating capacity and are synthetic organic materials that involve non-environmentally-friendly raw materials and complex reactions. There is a need to find a special media for purifying lithium extraction solutions that has good selectivity to boron.

[0009] Granular iron oxide, commonly in the form of granular ferric hydroxide (GFH) or granular ferric oxide (GFO), has been widely used to purify drinking water through a process called adsorption and / or catalytic oxidation. GFO is considered environmentally friendly because it does not introduce harmful chemicals or by-products into the water. GFO, such as Applicant’s BAYOXIDE® E33 iron oxide adsorber, is commonly used to remove arsenic, antimony, vanadium and selenium from potable water, and phosphate from aquarium and surface water. It can also be used to remove silica from industrial wastewater prior to reverse osmosis process. However, the inventors are unaware of any reports of GFO being used to purify lithium extraction solutions.

[0010] SUMMARY OF THE INVENTION

[0011] The present disclosure provides use of granular iron oxide (GFO) for removing boron in lithium-containing aqueous solutions, such as lithium extraction solutions. A method of reducing boron concentration in a lithium-containing aqueous solution having boron impurities, preferably a lithium extraction solution, comprises contacting the lithium-containing aqueous solution with granular iron oxide, preferably iron oxide having an average particle size of 0.2 to 1.2 mm. Typically, the step of contacting comprises passing the lithium-containing aqueous solution through a column or bed containing the granular iron oxide to yield an effluent solution in which the amount of boron is reduced.

[0012] In some embodiments, the granular iron oxide is based on a defined yellow / brown a-Ferric oxide hydroxide structure that contains greater than 50% by weight of iron oxide. Preferably, the granular iron oxide contains less than 40 % by weight of iron hydroxide, more preferably less than 30% by weight of iron hydroxide. In certain embodiments, the granular iron oxide has a crystalline structure, a bulk density of 0.4 to 0.60 g / cm3and a BET specific surface area of 120 to 200 m2 / g. In certain embodiments, the granular iron oxide has an amorphous structure, a bulk density of 0.7 to 0.9 g / cm3and a BET specific surface area larger than 250 m2 / g. In certain embodiments, the granular iron oxide has a moisture content no greater than 20% by weight.

[0013] Often the lithium-containing solution will contain high amounts of lithium that are not found in potable water sources, such as greater than 5 ppm, more often greater than 100 ppm, or greater than 1,000 ppm, or greater than 10,000 ppm, or even greater than 100,000 ppm of lithium. The lithium-containing aqueous solution will typically contain other impurities selected from calcium, magnesium, boron, silica, , barium, strontium and heavy metals, most typically, magnesium, boron, silica and calcium. The disclosed method of removing boron has proven successful where boron concentration in the lithium-containing solution prior to contact with the granular iron oxide is greater than 1 ppm, or 10 ppm, or 100 ppm, up to as high as 10,000 ppm.

[0014] Advantageously, the disclosed method is able to remove greater than 50% of the boron in the lithium-containing solution after contact with the granular iron oxide, such as greater than 60%, or even greater than 95% in solutions containing less than 10 ppm of lithium. That is, the effluent of the disclosed method will have a boron concentration that is reduced by at least 50%, such as greater than 60% or greater than 95%. The disclosed method reduces the concentration of boron with a correspondingly controlled loss of lithium (in the effluent), such as less than 15% loss of lithium, or less than 10% loss of lithium in the lithium-containing solution after contact with the granular iron oxide.

[0015] More advantageously, if the lithium-containing solution has silica and / or heavy metals as an impurity, the granular iron oxide (GFO) can remove both boron, silica and heavy metals simultaneously, which is not economically feasible or operationally possible with other media technologies including ion exchange resins. This greatly simplifies the impurity treatment process of lithium brine.

[0016] DETAILED DESCRIPTION

[0017] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In case of any such conflict, or a conflict between the present disclosure and any document referred to herein, the present specification, including explanations of terms, will control. The singular terms “a,” “an,” and “the” include plural referents unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise. The term “comprising” means “including;” hence, “comprising A or B” means including A or B, as well as A and B together. All numerical ranges given herein include all values, including end values (unless specifically excluded) and intermediate ranges.

[0018] Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, suitable methods and materials are described herein. The disclosed materials, methods, and examples are illustrative only and not intended to be limiting.

[0019] As used herein, “removing” means the concentration of one or more substances in a solution is reduced to a desired level. For example, “removing boron from lithium-containing water” means reducing the concentration of boron, such as in the form of borate, in lithium- containing water to a desired level.

[0020] “Aqueous solution" refers to a solution in which water is a dissolving medium or solvent. The pH of the aqueous solution may be adjusted by any means known by those of ordinary skill in the art, including by the addition of potassium hydroxide, ammonia, calcium hydroxide, and / or sodium hydroxide to raise the pH, and the addition of hydrochloric acid or other inorganic acids to lower the pH.

[0021] “Lithium-containing aqueous solution” may contain elements in addition to lithium. As used herein, “contacting” means placing two or more substances, such as iithium- containing water and a filter media, together so that desired adsorption occurs to a desired extent.

[0022] Granular iron oxide is a filtering composition that can be used for reducing amounts of boron in lithium-containing aqueous solutions, like lithium extraction solutions, by contacting the lithium-containing aqueous solutions with the granular iron oxide.

[0023] Granular iron oxide has a high surface area and a high affinity for binding various contaminants present in water. When water passes through a filter bed containing granular iron oxide, contaminants such as boron, as well as silica, arsenic, heavy metals (like lead, cadmium, and chromium), phosphates, and certain organic compounds are adsorbed onto the surface of the iron oxide particles.

[0024] “Granular iron oxide" as used herein refers to iron oxide that has an average particle size of 0.2 to 1 .2 mm, preferably iron oxide having an average particle size of 0.4 to 1 .0 mm, as determined by dynamic light scattering or a sieving method. The granular iron oxide may contain iron hydroxide, but the amount of iron hydroxide is less than the amount of iron oxide. That is, the granular iron oxide contains greater than 50% by weight of iron oxide.

[0025] Iron oxide is preferably Hematite (a-Fe2O3). The iron oxide alone can be used as a boron adsorbent / desorbent or can be a mixture with other forms of iron oxide or iron hydroxide, such as Akaganeite (P-FeOOH). Lepidorocrocite (y-FeOOH), Ferryhydrite (FesO? (OH).4H2O). Preferably, the granular iron oxide is based on a defined yellow / brown a-Ferric oxide hydroxide structure that is predominantly Hematite and contains less than 40 % by weight of iron hydroxide, more preferably less than 30% by weight of iron hydroxide. In certain embodiments, the granular iron oxide has a crystalline structure, a bulk density of 0.4 to 0.60 g / cm3, and a BET specific surface area of 120 to 200 m2 / g. In certain embodiments, the granular iron oxide has an amorphous structure, a bulk density of 0.7 to 0.9 g / cm3and a BET specific surface area larger than 250 m2 / g. In certain embodiments, the granular iron oxide has a moisture content no greater than 20% by weight.

[0026] The lithium-containing solution typically remains in contact with the filtering compositions for a period of time sufficient to remove a solute, such as boron ions, to a desired concentration range. In particular examples, the empty bed contact time (EBCT) ranges from about 1 to about 10 minutes, such as about 2 to about 5 minutes, is sufficient to remove boron to the desired concentration, such as below about 0.2 ppm, when the concentration of boron in solution is at about 10ppm. Disclosed processes can be used to remove more than 95% of boron species from aqueous solution. In more particular implementations, concentrations of less than 0.2 ppm boron are achievable. In particular implementations, adjustment of the solution pH is not required prior to passage through the filtering composition. Particular disclosed adsorbents are effective over a wide pH range, such as from about 6.0 to about 11.0, such as about 6.5 to about 9.5.

[0027] Overtime, the granular iron oxide bed becomes saturated with contaminants and loses its effectiveness. However, unlike other adsorbents, such as activated carbon, granular iron oxide can be regenerated in situ. This means that it can be treated with a chemical solution to remove the adsorbed contaminants and restore its adsorption capacity, allowing for longer operational lifetimes and lower operating costs.

[0028] EXAMPLE

[0029] Experimental:

[0030] 1 . Materials

[0031] Bayoxide® E33 synthetic iron hydroxide oxide o-FeOOH granules from LANXESS have a minimum Fe2Os content of 70%, bulk density of 0.46-0.57 g / cm3, specific surface area of 120-200 m2 / g, moisture content max 20%, and density of about 4.0 g / ml.

[0032] Sodium tetraborate decahydrate, sodium chloride, lithium chloride, 1N sodium hydroxide solution and calcium chloride were obtained from Thermo Fisher Scientific.

[0033] Three test solutions were prepared as shown below:

[0034] The targeted concentrations of ionic species are shown in the below table:

[0035] 2. Test procedure

[0036] (a). Lithium extraction solution preparation

[0037] Appropriate amounts of sodium tetraborate decahydrate, sodium chloride, lithium chloride and calcium chloride were added to deionized water to provide 10, 100 and 1000 ppm of the boron in a brine matrix solution containing 14000 ppm lithium, 14000 ppm sodium and 1000 ppm calcium. The solutions were prepared gravimetrically, and the pH was adjusted to about 9.0 using 1N NaOH.

[0038] (b). Column test

[0039] The test was performed on a glass column (0.9 inch diameter, and 20 inches long) manufactured by Ace Glass Inc.. The testing procedure is shown below:

[0040] (1). Add 50ml Bayoxide® E33 granules into the column

[0041] (2). Backwash at 50% bed expansion for 15-20 min until the backwash water becomes clear

[0042] (3). Feed 500ml Li solutions containing different amounts of boron to the column at 12.5ml / min

[0043] (4). Collect all effluent in a bottle, and measure the target species concentration

[0044] (5). The % removal of the species were calculated by the formula:

[0045] (influent species concentration - effluent concentration) / influent species concentration * 100

[0046] Results:

[0047] Boron removal from synthetic lithium extraction solutions by Bayoxide® E33 granules

[0048] Boron could be removed from LiCI and NaCI brines, even at high concentration level (1 ,000 ppm). The efficiency of boron removal was significantly higher at relatively low concentrations such as 10 ppm. In practical operations, the granular iron oxide media can be arranged in multiple vessels in series, for example, a led / lag / polisher design. The lead vessel will remove a large load of the boron from feed, then the lag vessel further reduces the boron concentration to a relatively lower level. Finally, the polisher vessel will remove the boron to very low levels at higher efficiency. After the lead vessel is exhausted, the lag vessel can be moved to the lead position, and the polisher vessel can be moved to the lag position. The former lead vessel will then be placed as the polisher vessel after regeneration.

[0049] The presently disclosed use and methods involving granular iron oxide may be used in a variety of filtration applications. More particularly, the disclosed methods can be used to remove unwanted species, from lithium extraction solutions, including boron, silica, arsenic, fluoride, phosphate, vanadium, and heavy metals.

Claims

CLAIMSWhat is claimed is:

1. A method for reducing boron concentration in a lithium-containing aqueous solution comprising contacting the lithium-containing solution with granular iron oxide.

2. The method according to claim 1 , wherein the lithium-containing solution has greater than 5 ppm lithium prior to contact with the granular iron oxide.

3. The method according to claim 1, wherein the lithium-containing solution has a pH of about 6 to about 11.

4. The method according to claim 2, wherein the lithium-containing aqueous solution is a lithium extraction solution.

5. The method according to claims 1 or 2, wherein the granular iron oxide contains greater than 50% by weight, preferably greater than 70% by weight of iron oxide (Fe2O3).

6. The method according to claims 1 or 2, wherein the granular iron oxide contains less than 40 % by weight of iron hydroxide, more preferably less than 30% by weight of iron hydroxide.

7. The method according to any of the preceding claims, wherein the granular iron oxide has moisture content no greater than 20% by weight.

8. The method according to any of the preceding claims, wherein the average particle size of the granular iron oxide is 0.2 to 1.2 mm.

9. The method according to any of the preceding claims, wherein the granular iron oxide has a crystalline structure, a bulk density of 0.4 to 0.6 g / cm3, and a BET specific surface area is 120 to 200 m2 / g.

10. The method according to any of claims 1 -8, wherein the granular iron oxide has an amorphous structure, a bulk density of 0.7 to 0.9 g / cm3, and a BET specific surface area is larger than 250 m2 / g.

11. The method according to any of the preceding claims wherein the step of contacting comprises passing the lithium-containing aqueous solution through a column or bed containing the granular iron oxide to yield an effluent solution in which the amount of boron is reduced.

12. The method according to any of the preceding claims, wherein the concentration of boron is reduced by 60% or greater than 60%.

13. A method for removing boron from a lithium extraction solution comprising passing the lithium extraction solution through a column or bed of granular iron oxide.

14. The method according to claim 13, wherein the granular iron oxide contains greater than 70% by weight of a-Fe2O3and no greater than 20% by weight moisture content.

15. Use of granular iron oxide for removing boron from a lithium extraction solution.

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