Patent Description:
With the advancement of battery technology for applications in electronics, in particular lithium-based batteries, the value of lithium as a commodity has risen substantially in the market in recent years. Lithium salts are extracted and purified from salt brines around the world.

In commonly used commercial extraction methods, naturally occurring lithium containing brines are concentrated by evaporation of water in a series of evaporation ponds. As the brine concentrates, various salts such as halite and potash precipitate out. The concentrated brine is then transported by tank trucks and unloaded into storage tanks. A typical concentrated brine can comprise varying amounts of lithium (Li), boron (B), magnesium (Mg), calcium (Ca), sodium (Na), iron (Fe), potassium (K), chlorine (Cl), sulfate, and nitrate. Impurities are then removed from the concentrated brine. Various commercial methods are available for removal of such impurities. In this connection, please see, for example, <CIT>, <CIT>, <CIT>, and<NPL>.

<CIT> discloses a process for the recovery of sodium tetraborate from aqueous boron-containing solutions utilizing sodium metaborate and boric acid intermediates. A boron-containing first feed solution is extracted with a <NUM>,<NUM>-diol to produce a boron-rich first organic phase and a boron-depleted first aqueous phase. The first organic phase is separated from the first aqueous phase and extracted with an aqueous alkaline solution comprising an alkali metal hydroxide in a second separation zone, to produce a second aqueous phase rich in sodium metaborate and a boron-depleted second organic phase, which are separated. A boron-containing second feed solution is contacted, in a third separation zone, with a water-insoluble aromatic polyol to produce a boron-depleted third aqueous phase and a boron-rich third organic phase, which are separated. The third organic phase is contacted with a mineral acid in a fourth separation zone to produce a fourth aqueous phase rich in boric acid and a boron-depleted fourth organic phase, which are separated. Boric acid from the fourth aqueous phase is then reacted with sodium metaborate from the second aqueous phase to produce a fifth aqueous phase rich in sodium tetraborate.

<CIT> describes the production of battery grade metallic lithium from brine by a process comprising one or more extractions steps to remove residual boron using an aliphatic alcohol, such as isooctyl alcohol, and a phase modifier, such as tributylphosphate, that is dissolved in an aromatic solvent. The organic extract is re-extracted in one or more steps with an alkaline solution such as sodium hydroxide.

In one commercial method, impurities are removed from a concentrated brine through multiple purification steps, prior to the conversion to high purity lithium products, such as lithium carbonate and lithium chloride. One of the purification steps, namely the solvent extraction (SX) process, is used to remove boron from the brine, reducing its content, for example, from a nominal <NUM>,<NUM> ppm to less than <NUM> ppm. The SX process can comprise: (a) acidification of the brine with hydrochloric acid to convert the boron species to boric acid, (b) extraction of boron from the acidified brine by contacting it with an alcohol-kerosene organic solution in multistage countercurrent liquid-liquid extraction operations, (c) re-extraction of boron from the boron loaded organic solution to less than about <NUM> ppm with water or diluted caustic in multistage countercurrent re-extraction operations, so the organic can be recycled to (b). Overall, the SX process requires a volumetric ratio of water to concentrated brine of greater than approximately <NUM>:<NUM>, generating a tailwater waste stream that is enriched with boron, for example approximately <NUM>,<NUM> to <NUM>,<NUM> ppm of boron. The tailwater waste stream is then transported to the evaporation ponds. Limitations often encountered in attempting to enlarge the output of such methods is the lack of availability of water and the pre-established capacity of the evaporation ponds.

Thus, there is a need for new and improved methods for concentrating lithium containing brines that minimize or reduce the impact from these and other limitations.

In general, the present disclosure provides one or more methods for extracting boron from an organic solution comprising (A) combining in a container (i) a combination comprising an alcohol, an organic solvent, and boron; and (ii) an aqueous solution comprising <NUM> wt. % to <NUM> wt. % of an alkali hydroxide based on total weight of the aqueous solution. The molar ratio of the alkali hydroxide to the boron is <NUM> to <NUM>, and the volume ratio of the combination to the aqueous solution is in the range of from <NUM>:<NUM> to <NUM>:<NUM>. The method also includes (B) heating content of the container to a temperature in the range of from <NUM> to <NUM> until the content comprises an organic layer and an aqueous layer, and the aqueous layer comprises greater than <NUM>% of the boron from the combination. The method also includes (C) separating the aqueous layer from the content of the container.

The method the invention can also include (D) separating greater than <NUM>% of the boron from the aqueous layer.

The method of the invention can also include (E) using the aqueous layer remaining after (D) as all or part of the aqueous solution in (A).

The temperature in (B) can be in the range of from <NUM> to <NUM> or in the range of from <NUM> to <NUM>, for example.

The alkali hydroxide can be, for example, sodium hydroxide, potassium hydroxide, or lithium hydroxide.

According to one embodiment of the invention the boron is separated from the aqueous layer as sodium borate.

The alkali hydroxide can be present in the aqueous solution, for example, in an amount ranging from <NUM> wt. % to <NUM> wt. %, based on the total weight of the aqueous solution.

To more clearly define the terms used in this disclosure, the following definitions are provided, which are applicable to this disclosure.

In this disclosure, features of the subject matter are described such that, within particular aspects, a combination of different features can be envisioned. For each and every aspect and each and every feature disclosed herein, all combinations that do not detrimentally affect the designs, compositions, processes, or methods described herein are contemplated with or without explicit description of the particular combination. Additionally, unless explicitly recited otherwise, any aspect or feature disclosed herein can be combined to describe inventive designs, compositions, processes, or methods consistent with the present disclosure.

In this disclosure, while compositions and processes are often described in terms of "comprising" various components or steps, the compositions and methods can also "consist essentially of" or "consist of" the various components or steps, unless stated otherwise. For example, a method consistent with certain aspects of the disclosed subject matter can comprise; alternatively, can consist essentially of; or alternatively, can consist of; a combining step, a heating step, and separating step.

The terms "a," "an," and "the" are intended to include plural alternatives, e.g., at least one, one or more, and one or more than one, unless otherwise specified. For example, the disclosure of "a solvent," is meant to encompass one, or mixtures or combinations of more than one, solvent, unless otherwise specified.

The term "combining" is used herein to describe any suitable form of combining two or more components, including, for example, batch combining or co-feeding.

The term "combination" means any combination of the two or more components, and can include mixtures, solutions, suspensions, and other forms, all of which will be familiar to those skilled in the art.

Various numerical ranges are disclosed herein. When a range of any type is disclosed or claimed herein (e.g., "ranging from. ", "in the range of from. ", "in a range of from") the intent is to disclose or claim individually each possible number that such a range could reasonably encompass, including end points of the range as well as any sub-ranges and combinations of sub-ranges encompassed therein, unless otherwise specified. For example, the present disclosure recites heating the contents of the container to a temperature in a range from <NUM> to <NUM> in certain aspects. By a disclosure that the temperature can be in a range from <NUM> to <NUM>, the intent is to recite that the temperature can be any temperature within the range and, for example, can be equal to about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. Additionally, the temperature can be within any range from <NUM> to <NUM> (for example, the temperature can be in a range from <NUM> to <NUM>), and this also includes any combination of ranges between <NUM> and <NUM>. Likewise, all other ranges disclosed herein should be interpreted in a manner similar to this example.

Embodiments disclosed herein can provide the materials listed as suitable for satisfying a particular feature of the embodiment delimited by the term "or. " For example, a particular feature of the disclosed subject matter can be disclosed as follows: Feature X can be A, B, or C. It is also contemplated that for each feature the statement can also be phrased as a listing of alternatives such that the statement "Feature X is A, alternatively B, or alternatively C" is also an embodiment of the present disclosure whether or not the statement is explicitly recited.

Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the subject matter described herein, the typical methods and materials are herein described.

Illustrative aspects of the subject matter claimed below will now be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

The present disclosure is generally directed to one or more methods for extracting boron from an organic solution.

In an aspect, the method comprises combining a combination with an aqueous solution comprising an alkali hydroxide. The combination comprises an alcohol, an organic solvent, and boron, which is combined with an aqueous solution comprising <NUM> wt. % to <NUM> wt. % of an alkali hydroxide, wherein the molar ratio of alkali hydroxide to boron is <NUM> to <NUM>. As a non-limiting example, the combination can comprise the boron that has been extracted from the acidified brine with an alcohol-kerosene organic solution, as mentioned above in the Background section. As another non-limiting example, the combination can comprise an organic solution comprising boron with an aqueous solution comprising an alkali hydroxide. For example, the organic solution may comprise <NUM> to <NUM> ppm boron, <NUM>-<NUM> vol. % isooctyl alcohol (e.g., EXXAL™-<NUM> commercially available from ExxonMobil), and <NUM>-<NUM> vol. % kerosene.

The combining step can be conducted in any suitable type process, including for example, in a batch process, in a semi-batch process, in a continuous stirred tank reactor, and in other type processes, as will be familiar to those skilled in the art.

The aqueous solution comprises an alkali hydroxide in an amount ranging from <NUM> wt. % to <NUM> wt. %, based on the total weight of the aqueous solution. The aqueous solution may comprise an alkali hydroxide in an amount ranging from <NUM> wt. % to <NUM> wt. %, based on the total weight of the aqueous solution. The aqueous solution may comprise an alkali hydroxide in an amount ranging from <NUM> wt. % to <NUM> wt. %, based on the total weight of the aqueous solution. The aqueous solution may comprise an alkali hydroxide in an amount of <NUM> wt. % to <NUM> wt. %, based on the total weight of the aqueous solution.

Without being bound by a particular theory, as the concentration of the alkali or other suitable hydroxide increases, the need for water in methods in accordance with this disclosure is substantially reduced as compared to currently available commercial methods. Further, this can eliminate any need for multistage re-extraction mixers/settlers. Still further, this can aid in reducing the volume of aqueous waste stream, and recovery of boron value as sodium borate (Borax) can be precipitated and sold as a byproduct.

Examples of suitable alkali hydroxides include without limitation sodium hydroxide, potassium hydroxide, and lithium hydroxide. Given the teachings of this specification, and depending on the composition of the combination, such as the boron loaded alcohol-kerosene organic solution, those skilled in the art may identify other suitable alkali hydroxides that may be used in accordance with this disclosure.

The combined combination and the aqueous solution has a molar ratio of alkali hydroxide to boron of <NUM> to <NUM>. The combined combination and the aqueous solution may have a molar ratio of alkali hydroxide to boron of <NUM> to <NUM>. The combined combination and the aqueous solution may have a molar ratio of alkali hydroxide to boron of <NUM> to <NUM>.

Examples of suitable alcohols include without limitation one or more of aliphatic alcohols, diols, and polyols, for example, iso-octanols, <NUM>-ethylhexanol, <NUM>-ethyl-<NUM>,<NUM>-hexanediol, <NUM>-t-butylcatechol, <NUM>-butyl-<NUM>-ethyl-<NUM>,<NUM>-propanediol, and EXXAL™-<NUM>. Those skilled in the art, given the teachings of this specification, can select other alcohols that are suitable for use in this invention.

Examples of suitable organic solvents include without limitation kerosene, aliphatic alkanes having six to <NUM> carbons, such as heptane, hexane, octane, and aromatics such as toluene, xylene, and petroleum ether. ESCAID™-<NUM>, which is commercially available from ExxonMobil, is another example of a suitable organic solvent that may be used in accordance with this disclosure. Those skilled in the art, given the teachings of this specification, can select other organic solvents that are suitable for use in this invention. In one aspect of this invention, the organic solvent is a diluent.

The volume ratio of the combination to the aqueous solution that are combined is in the range of from <NUM>: <NUM> to <NUM>: <NUM>. The volume ratio of the combination to the aqueous solution may be at least <NUM>:<NUM>. The volume ratio of the combination to the aqueous solution may be at least <NUM>: <NUM>. The volume ratio of the combination to the aqueous solution may be at least <NUM>: <NUM>.

In an aspect, the aqueous solution comprising an alkali hydroxide and the combination comprising an alcohol, an organic solvent, and boron, is heated to a temperature so as to form an organic layer and an aqueous layer. For this, the content of the container resulting from the combining of the aqueous solution and the combination comprising an alcohol, an organic solvent, and boron, is heated to a temperature of <NUM> to <NUM>. During heating, the content forms into an organic layer and an aqueous layer, and boron is extracted from the combination into the aqueous layer. The temperature is in the range of from <NUM> to <NUM>. The temperature may be in the range of from <NUM> to <NUM>. The temperature may be in the range of from <NUM> to <NUM>.

The heating is continued until the aqueous layer comprises greater than <NUM>% of the boron from the combination. The duration of the heating can be determined by those skilled in the art, depending on the composition of the content of the container, and given the teachings of this disclosure.

In an aspect, the method comprises separating the aqueous layer from the organic layer. For example, the aqueous layer can then be separated from the content of the container by means familiar to those skilled in the art. Such methods can additionally comprise separating greater than <NUM>%, or greater than <NUM>%, of the boron from the aqueous layer. The boron can be separated in any suitable form as will be familiar to those skilled in the art, for example, as sodium borate salts, and by any suitable means as will be familiar to those skilled in the art, for example, by crystallization after cooling or concentration by evaporation. Further, after separation of the boron, the remaining aqueous layer can be used as all or part of the aqueous solution that is combined with the combination comprising an alcohol, an organic solvent, and boron.

In an aspect, the separation of the aqueous layer from the content of the container can be done by means known to those of skill in the art, for example, without limitation, by decanting, use of a phase separator, or use of a centrifuge; and recovering boron from the aqueous layer can comprise recovering the boron as sodium borate, and by means known to those of skill in the art, for example, without limitation, by precipitation.

The methods disclosed herein are advantageous in that the need for water in such methods is substantially reduced as compared to currently available commercial methods. For example, use of methods of this invention can reduce water consumption from <NUM> to <NUM> - <NUM> unit volume per unit volume of brine, as compared to use of current methods. Further, methods of this invention eliminate any need for multistage re-extraction mixers/settlers. Also, use of methods of this invention aid in reducing the volume of aqueous waste stream, and recovery of boron value as sodium borate (borax) can be precipitated and sold as a byproduct.

To facilitate a better understanding of the present disclosure, the following examples of embodiments are provided. In no way should the following examples be read to limit, or to define, the scope of the appended claims.

A <NUM>-ml PYREX™ flask was charged with <NUM> of acidified concentrated brine that contained <NUM>,<NUM> ppm boron, and with <NUM> of an organic solution, which contained <NUM> vol. % EXXAL™-<NUM> and <NUM> vol. % ESCAID™-<NUM>. The bottle was vigorously shaken by hand for <NUM> minutes and then the mixture was transferred to a separatory funnel for phase separation. The boron concentration in the separated organic layer was determined by Inductively Coupled Plasma (ICP) to be <NUM>,<NUM> ppm. The instrument used for the ICP determination is a Model <NUM> Dual View available from PerkinElmer, Inc.

A <NUM>-ml PYREX™ round-bottomed flask with a stir bar was then charged with <NUM> portion of the separated organic layer (<NUM> mmol B) and with <NUM> of <NUM> wt. % sodium hydroxide solution (<NUM> mmol NaOH). The mixture was heated to <NUM> via a heating mantle with stirring. Samples of the top organic layer, after allowing the phases to settle, were taken after <NUM>, <NUM>, and <NUM> minutes of mixing. The aqueous layer at the bottom, which was a slurry mixture, was filtered using a <NUM>-µ filter paper. The composition of the organic layer and the aqueous filtrate are given in Table <NUM>.

In the above Example <NUM>, the volume ratio of the separated organic layer to the sodium hydroxide solution is about <NUM>:<NUM>.

A <NUM>-ml PYREX™ round-bottomed flask with a mechanical overhead stirrer was charged with <NUM> of an organic solution that contained <NUM>,<NUM> ppm boron (<NUM> mmol B), <NUM> vol. % EXXAL™-<NUM> and <NUM> vol. % ESCAID™-<NUM>, and with <NUM> of an aqueous caustic solution that contained <NUM> wt. % NaOH (<NUM> mmol NaOH). The mixture was heated to <NUM> with an agitator speed of <NUM> rpm. After <NUM> minutes of mixing at <NUM>, the agitation was stopped to allow the phases to settle. The compositions of the top organic and bottom aqueous layers are given in Table <NUM>. The boron concentration in the separated organic layer was determined by Inductively Coupled Plasma (ICP). The instrument used for the ICP determination is a Model <NUM> Dual View available from PerkinElmer, Inc.

In the above Example <NUM>, the volume ratio of the organic solution to the aqueous caustic solution is about <NUM>: <NUM>.

The reactor was a jacketed glass vessel of <NUM> inch inner diameter. The mixing was provided by an impeller with dual <NUM> inch diameter TEFLON™ pitched blades, which was connected to a speed controller. An organic solution that contained <NUM>,<NUM> ppm boron, <NUM> vol. % EXXAL™-<NUM> and <NUM> vol. % ESCAID™-<NUM>, and an aqueous caustic solution that contained <NUM>% NaOH were co-fed to the reactor at a constant flow rate of <NUM>/min and <NUM>/min, respectively, while maintaining the reaction temperature at <NUM> with an agitator speed of <NUM> rpm. The reaction mass left the reactor via an overflow port, located at approximately <NUM>-ml reactor volume, to a <NUM>-liter receiver. Samples were withdrawn directly from the reactor at each turnover volume. The composition of the organic layer samples are given in Table <NUM>. The boron concentration in the separated organic layer was determined by Inductively Coupled Plasma (ICP). The instrument used for the ICP determination is a Model <NUM> Dual View available from PerkinElmer, Inc.

Claim 1:
A method comprising:
(A) combining in a container:
(i) a combination comprising an alcohol, an organic solvent, and boron; and
(ii) an aqueous solution comprising <NUM> wt.% to <NUM> wt.% of an alkali hydroxide based on total weight of the aqueous solution;
(iii)wherein the molar ratio of the alkali hydroxide to the boron is <NUM> to <NUM>;
(iv) wherein the volume ratio of the combination to the aqueous solution is in the range of from <NUM>:<NUM> to <NUM>:<NUM>; and
(B) heating the contents of the container to a temperature in the range of from <NUM> to <NUM> until the contents of the container comprises an organic layer and an aqueous layer, and the aqueous layer comprises greater than <NUM>% of the boron from the combination; and
(C) separating the aqueous layer from the contents of the container.