KR20230051148A - How to recover lithium from brine - Google Patents

Abstract

A method for recovering lithium ions from lithium-containing brine is to contact the lithium-containing brine with a lithium ion sieve (where LIS includes an oxide of titanium or niobium) in a first stirred reactor to obtain lithium ions with the lithium ion sieve. forming a complex and decomplexing lithium ions from the lithium ion sieve in a second stirred reactor to form a lithium ion sieve and an acidic lithium salt eluent.

Description

How to recover lithium from brine

Cross-Reference with Related Applications

This application is U.S. filed on December 27, 2017. Part-continuation-in-part of co-pending application Ser. No. 16/224,463 filed on Dec. 18, 2018, claiming the benefit of Provisional Application No. 62/610,575, Continuing-in-part applications, all of which are expressly incorporated by reference into this application.

1. Field of Invention:

The present invention relates generally to methods of recovering ions from brine, and more particularly to methods of recovering lithium ions from brine.

2. Description of Background Art:

As a result of recent interest in the use of lithium ion batteries for electric vehicles and stationary power storage, primarily in relation to renewable energy systems, including those from wind, solar, and tidal sources, the demand for lithium has grown significantly. increased and could soon exceed supply. Potentially many sources of lithium are available from a variety of sources, such as seawater, brackish water, geothermal fluids, and continental saline lakes. As used herein, “brine” and “brines” refer to these various lithium-containing solutions. However, to date, there have been few viable methods for recovering lithium from these sources without extensive enrichment by evaporation, since the concentration of lithium in these sources is typically very low. Also, much higher concentrations of other metal ions, such as sodium, potassium, calcium, and magnesium, interfere with the recovery of lithium.

Ion exchange is a well-known technique for recovering low concentrations of metal ions from aqueous solutions. However, conventional ion exchange resins, such as strong acid cation exchange resins with sulfonic acid functional groups and chelating resins with iminodiacetate groups, have a higher preference for multivalent ions that may be present, such as calcium and magnesium. The selectivity for lithium can be similar to that for other monovalent ions, such as sodium and potassium, but the presence of these competing monovalent ions, which are usually present in brine in very excessive amounts, makes recovery of lithium impracticable.

Inorganic ion exchange media, such as ionic sieves, based on manganese, titanium, or other oxides are potentially useful for recovering lithium from brines containing high concentrations of competing ions such as calcium, magnesium, sodium, and potassium. Confirmed. These materials may be referred to as lithium ion sieves (LIS). LIS shows a high preference for lithium because the LIS exchange site is so narrow that Na ⁺ (0.102 nm), K ⁺ (0.138 nm), and Ca ² have larger ionic radii than those of ^Li (0.074 nm). ⁺ (0.100 nm) cannot enter the exchange site. The ionic radius of the Mg ²⁺ ion (0.072 nm) is similar to that of Li ⁺ , but a large amount of dehydration is required to allow the magnesium ion to enter the exchange site so that the selectivity for Mg ²⁺ is maintained. Energy is needed.

However, LIS has a number of disadvantages. First, it is weakly acidic in nature and, as a result, has a reduced capacity at lower pH levels. Second, it is not stable in acid solution because some of its components are soluble in acid. As it deteriorates, it loses its ability to capture lithium and must be replaced frequently. Replacing the LIS means a significant cost. Moreover, when the LIS is installed in a conventional column, removal and replacement of the deteriorated LIS is difficult and time consuming. Finally, LIS is synthesized as a fine powder and therefore cannot be used in a fixed bed, like conventional ion exchange resins, due to its high pressure drop. Numerous attempts have been made to improve morphology, for example, through granulation, foaming, membranes, fibers, and magnetization. However, when these powders agglomerate to form larger geometries, kinetics as a result of clogging of pores and active exchange sites by binders and, typically, lower surface area to volume/mass ratios by larger particle sizes. it is seriously damaged

See, for example, Chitrakar et al. ("Lithium Recovery from Salt Lake Brine by H ₂ TiO ₃ ," Dalton Transactions , 43(23), pages 8933-8939, June 21, 2014) (hereinafter "Chitraka") relates to the synthesis, characterization, and laboratory evaluation of lithium selective adsorbents based on metatitanic acid. However, Chitraka does not mention industrial processes and does not discuss the problem of solid/liquid separation or washing of brine and eluent from adsorbents on an industrial scale. For example, an adsorption test of Chitraka was performed in a beaker at an adsorbent solids concentration of 20 g/L, and an elution test with HCl was performed at an adsorbent solids concentration of 10 g/L. Chitraka does not disclose how to use the adsorbent on a continuous industrial scale. In particular, the laboratory filtration used in the test will not be applicable on an industrial scale.

Thus, there is still a need to improve a method for recovering lithium from brine using a lithium ion sieve that overcomes the above disadvantages.

Summary of Invention

In one aspect, the invention relates to contacting a lithium-containing brine with a lithium ion sieve for less than about 1 hour in a first mixed or stirred reactor to form a lithium ion complex with the lithium ion body and a second mixed or stirred reactor. A method for recovering lithium ions from a lithium-containing brine by decomplexing the lithium ions from the lithium ion sieve in a reactor to form a lithium ion sieve and an acidic lithium salt eluent is provided.

In one embodiment, the method for recovering lithium ions from a lithium-containing brine comprises contacting the lithium-containing brine with a lithium ion sieve for less than about 1 hour in a first mixed or stirred reactor to form a lithium ion complex with a lithium ion sieve. including forming The method then includes decomplexing lithium ions from the lithium ion sieve in a second mixed or stirred reactor to form an acidic lithium salt eluent solution separated from the lithium ion sieve. The lithium ion sieve may include an oxide of titanium or niobium (eg, metatitanic acid or lithium niobate).

Decomplexation can be performed by elution with an acid. The concentration of the acid may be maintained at a constant value through the addition of the acid. The concentration of the acid should be less than 0.1 M and should preferably correspond to a pH greater than 1 and less than 3, most preferably a pH of about 2. The average contact time of the acid with the lithium ion complex with the lithium ion sieve may be less than 1 hour. The acid may be hydrochloric acid or sulfuric acid.

The pH of the first reactor can be maintained at a constant value through the addition of alkali. The pH can be maintained at a constant value above 4 and below 9 or above 6 and below 8. The alkali can be sodium hydroxide (NaOH), ammonium hydroxide, potassium hydroxide, sodium carbonate, magnesium hydroxide, calcium hydroxide, or anhydrous ammonia. For example, the alkali can be sodium hydroxide at a concentration of less than 8% w/w.

Greater than 90% of the lithium ion sieve may have an average particle diameter of less than 40 μm and greater than 90% of the lithium ion sieve may have an average particle diameter of greater than 0.4 μm. Greater than 90% by volume of the particles of the lithium ion sieve may be less than 100 μm in diameter and may be greater than 0.5 μm in diameter. Greater than 90% by volume of the particles of the lithium ion sieve may be greater than 0.5 μm in diameter. The method may further include removing the lithium ion sieve having an average particle diameter of less than 1 μm prior to contacting the lithium-containing brine with the lithium ion sieve.

The method includes separating a lithium ion complex with a lithium ion sieve from brine, using a solid/liquid separation device; and contacting the lithium ion complex with the lithium ion body with water prior to decomplexing in the second reactor. The method also includes separating the lithium ion sieve from the acidic lithium salt eluent solution using a solid/liquid separation device; contacting the lithium ion sieve with water after decomplexing in the second reactor to obtain a regenerated lithium ion sieve and dilute acid washing water; and adding the regenerated lithium ion sieve to the first reactor. The method may further include dewatering the lithium ion complex with the lithium ion sieve to a moisture content of less than 90% by weight prior to decomplexing the lithium ions from the lithium ion sieve in the second reactor. The method may also further include dewatering the regenerated lithium ion sieve before adding it to the first reactor. Contacting the lithium ion sieve with water is such that prior to adding the regenerated lithium ion sieve to the first reactor, the lithium ion sieve is sufficiently washed from the lithium ion sieve such that greater than 50% of the decomplexed lithium ions are washed from the lithium ion sieve. It may include contacting with water. Contacting the lithium ion sieve with water may also include more than one countercurrent flow such that greater than 50% of the lithium ions decomplexed from the lithium ion sieve are washed from the lithium ion sieve prior to adding the regenerated lithium ion sieve to the first reactor. It may involve contacting the lithium ion sieve with water in a stage. The method may also further include adding dilute acid wash water and additional concentrated acid to the second reactor.

The first reactor may include an ultrafiltration or microfiltration membrane. Air or other gas may be used to agitate the contents of the first reactor. The flux rate through an ultrafiltration membrane or microfiltration membrane can be greater than 30 LMH at a transmembrane pressure of less than 30 kPa.

The concentration of the lithium ion sieve may be greater than 50 g/L or greater than 100 g/L.

Further scope of the applicability of the present invention will become apparent from the detailed description given below. However, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description, the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of example only. have to understand

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be more fully understood from the detailed description given below and from the accompanying drawings, which are given by way of example only and not as limiting of the invention. In the drawings, like reference numbers are used to indicate like features from various views.
1 is a schematic diagram of an exemplary lithium extraction system for the present method.
2 is a graph showing the amount of metal ion capture as a function of pH.
3 is a graph showing the amount of lithium and titanium extracted as a function of hydrochloric acid concentration.
4 is a graph showing an exemplary LIS particle size distribution of a sample of lithium ion metatitanate sieve taken after several hours of air agitation in the slurry.
5 is a schematic diagram of an alternative lithium extraction system for the present method.
6 is a graph of lithium concentration as a function of time for an exemplary extraction test.
7 is a graph showing the amount of lithium and titanium extracted as a function of pH.
8 is a graph showing the effect of contact time on lithium capacity and calcium sequestration.

As a result of the disadvantages discussed above, lithium ion sieves have hitherto not been widely applied for industrial scale recovery of lithium from brine. The present invention overcomes these drawbacks, making the use of lithium ion sieves in the selective recovery of lithium from brine more commercially feasible.

The average particle diameter of conventional ion exchange resins is typically about 400-1250 micrometers. The RECOFLO® monolayer ion exchange process utilizes what is commonly considered the finest particle size used in large-scale industrial applications. These particles typically have an average particle diameter of 100-200 microns.

In contrast, the lithium ion sieve used in the present invention is preferably in powder form. The average particle size of the powder is not necessarily limited. However, the average particle size is preferably less than about 100 μm, more preferably 10 to 100 μm, even more preferably 20 to 100 μm, even more preferably 20 to 95 μm. Additionally, the average particle size may be between 0.4 and 40 μm. For example, greater than 90% (by volume) of the lithium ion sieve particles may be less than 100 μm in diameter and may be greater than 0.5 μm in diameter. In the same or different embodiments, greater than 90% (by volume) of the lithium ion sieve particles may be greater than 0.5 μm in diameter. Since these materials are synthesized as powders, agglomeration costs are avoided. Moreover, the larger surface area provided by these powders significantly improves the kinetics of the ion exchange process. In other words, the lithium ion body is not a composite bonded with a polymer or other binder.

A variety of lithium ion bodies are potentially useful for lithium recovery. Exemplary LIS include, but are not limited to, oxides of manganese and titanium. Specifically, an exemplary LIS may include an oxide of titanium, preferably metatitanic acid (MTA). However, the present invention is equally applicable to other types of lithium ion sieve media, such as manganese oxide and lithium niobate (i.e., niobate). The lithium ion body may also contain dopants other than oxides of titanium, niobium, or manganese. However, the content of the lithium ion sieve will be primarily oxides of titanium, niobium, or manganese.

In one embodiment of the present invention, the powdered lithium ion sieve medium may be contacted with a lithium-containing brine in a stirred tank reactor (STR or reactor). For example, the reactor may be a tank containing a liquid to be treated with a lithium ion sieve. The lithium ion sieve may be maintained in suspension by a mixer, which provides intimate contact of the lithium ion sieve with the brine, or by fluidization by an upward flow of liquid or gas bubbles. The pH of the brine in the reactor can be maintained at a constant level through the addition of an alkali such as sodium hydroxide (NaOH), ammonium hydroxide, potassium hydroxide, sodium carbonate, magnesium hydroxide, and calcium hydroxide. For example, the pH of the brine in the reactor can be maintained above 5 and below 9.

Many brines that can be treated by the present invention contain significant concentrations of magnesium. Neutralization of brines with alkalis can present some problems in the case of brines containing high concentrations of magnesium. Magnesium hydroxide does not generally precipitate at a pH below about 8, but when alkali is added, the localized high pH conditions at the point where the alkali contacts the brine result in precipitation of the magnesium hydroxide. Despite the fact that the pH of the total brine is lower than the theoretical precipitation pH, the sediment does not dissolve rapidly. The presence of magnesium hydroxide causes numerous problems. For example, it can adhere to the surface of LIS and inhibit the trapping of lithium. If the membrane is used for solid/liquid separation, it can reduce the permeate flux and possibly foul the membrane.

When sodium hydroxide is used, the problem of magnesium hydroxide precipitation is particularly severe and more pronounced at higher NaOH concentrations. When 50% w/w NaOH is used, a large amount of Mg(OH) ₂ that is not re-dissolved is produced. When a dilute NaOH solution is used, less Mg(OH) ₂ is produced and Mg(OH) ₂ re-dissolves faster. When 4% w/w NaOH is used, only very small amounts of Mg(OH) ₂ are produced, which re-dissolve in just a few seconds. As such, when sodium hydroxide is used, it is preferably present in a concentration of less than 8% w/w.

The use of dilute NaOH is disadvantageous in that it dilutes the barren brine. In locations where depleted brine must be re-injected into the ground, over-volumes of brine produced can be a problem, as more brine cannot be pumped back into the ground than is discharged.

This problem can be avoided by using ammonia for neutralization. Ammonia can be in the form of dry ammonia gas or liquid ammonium hydroxide, so the amount of brine overvolume is negligible. Even when anhydrous ammonia gas or 30% ammonium hydroxide is used, only a small amount of Mg(OH) ₂ precipitates at the point of injection, and this precipitate quickly re-dissolves and does not adversely affect the process.

After the ion exchange reaction is complete, the lithium-depleted (ie, exhausted) brine can be separated from the lithium ion sieve and removed from the reactor by various means. For example, the brine/lithium ion sieve slurry (ie, the loaded lithium ion sieve) may be contacted with water in an additional stirred reactor to remove residual brine before proceeding to the next step. When the particle size of the lithium ion sieve is greater than about 10 micrometers, gravity settling may be used. If the particle size is less than 10 microns, a filtration device such as a rotary drum vacuum or belt filter may be used. If the particle size is less than 1 micron, membrane filtration can be used. Combinations of these solid/liquid separation devices may advantageously be used. One example of a possible solid/liquid separation device would be a centrifuge.

After removal of the spent brine, the lithium ion sieve contained in the reactor may be contacted with an eluent. This eluent may be, inter alia, an acid such as hydrochloric acid (HCl) or sulfuric acid (H ₂ SO ₄ ). For example, an acid may be added at a concentration of less than approximately 0.1 M, preferably at a pH greater than 1 and less than 3, most preferably at a pH of about 2. Without intending to be bound by any particular theory, it is believed that the acid elutes (decomplexes) the lithium from the LIS, creating a concentrated lithium salt product solution and regenerating the LIS. As used herein, a "complex" is a combination of individual groups of atoms, ions, or molecules that combine to produce one large ion or molecule. As used herein, "decomplexing" is the act of separating individual atomic groups, ions, or molecules from such larger ions or molecules. Because the lithium ion sieve is selective for lithium over other metals, the ratio of lithium to other metals can be much higher in the product solution than in the feed brine.

After the lithium ion sieve is regenerated, the lithium ion sieve can be reused to treat more brine and extract more lithium.

In one embodiment of the invention, the method can be carried out continuously. Two reactor stages may be required in this continuous process. The brine may be continuously fed to the loading stage, where the lithium ion sieve is continuously contacted with the brine as a mixed slurry. Lithium ions can then be removed from the brine by being captured by a lithium ion sieve, resulting in exhausted brine and lithium-loaded LIS. The exhausted brine can then be separated from the lithium-loaded lithium ion sieve and removed from the reactor. The lithium-loaded lithium ion sieve, now separated from the brine, can be passed to the elution stage.

Regarding the contact time of the lithium ion sieve with brine, lithium ion metatitanate sieves are known to have very poor kinetic properties. It takes a relatively long time for lithium ions to diffuse through the narrow exchange site. Therefore, it can be expected that the amount of lithium captured by the LIS increases as the contact time in brine increases. Indeed, Fig. 4(b) of Chitraka shows the effect of LIS and saline contact time. These data clearly show that the amount of lithium captured by LIS increases over time and is generally the expected amount for any ion exchange sorbent. However, the effect of contact time on lithium capture over time was found to have the opposite effect, as shown in FIG. 8 . Specifically, lithium capacity decreases over time. As shown in Figure 8, the lithium dose decreased from 15.5 mg/g at 1 hour to 12.5 mg/g at 2 hours and further decreased to 12 mg/g after 71 hours. The Ca segregation coefficient also decreases with contact time. As the contact time increases, more calcium and less lithium are trapped in the LIS. Given enough time, larger calcium ions slowly diffuse into the narrow exchange sites to displace lithium. This phenomenon may not have been observed in the case of Chitraka, since the brine of Citraka has a much higher lithium concentration and a lower calcium concentration than the brine typically used in the present invention ([Li] = 1630 mg /L, [Ca] = 230 mg/L). In Fig. 8, the brine used in the experiment had a lithium concentration of 219 mg/L and a calcium concentration of 34,500 mg/L. Thus, to maximize lithium capacity and calcium sequestration, at least in the case of brines having relatively high calcium and low lithium concentrations (e.g., brines obtained from the Smackover Formation in southern Arkansas), LIS and brine contact time should be less than about 1 hour.

The eluent may be continuously supplied to the elution stage, and the lithium-loaded lithium ion sieve removed from the loading stage may be continuously contacted with the eluent as a mixed slurry. The lithium ion sieve and liquid are separated, and this separated liquid (i.e., eluent) is the lithium salt product solution.

The lithium content of the lithium ion sieve leaving the elution stage is significantly reduced and the lithium ion sieve can be recycled back to the loading stage for reuse. In this way, the lithium ion sieve can be reused many times and the method can be operated continuously.

In one embodiment, additional stages may be used as shown in FIG. 1 . Specifically, feed brine flows through line 2 into a first stirred reactor 4 containing a lithium ion sieve, as part of a loading stage. The lithium ion sieve is maintained in suspension by the mixer (6). The brine/lithium ion sieve slurry is maintained at a constant pH through the addition of NaOH through line (8). The brine-loaded lithium ion sieve flows through line 10 to an additional stirred reactor 12 as part of the washing stage. Exhausted brine is separated from the loaded lithium ion sieve and flows through line (14). The brine-loaded lithium ion sieve is maintained in suspension by the mixer 16. In the washing stage, the loaded lithium ion sieve is contacted with water via line 18 to wash the brine from the lithium ion sieve, thereby reducing cross-contamination of the lithium salt product by contaminant ions present in the feed brine. It is thought to be The cleaned and loaded lithium ion sieve flows through line 20 into a second stirred reactor 22 as part of the elution stage. Wash water is separated from the washed and loaded lithium ion sieve and flows through line 24 to return to first stirred reactor 4. The washed and loaded lithium ion sieve is maintained in suspension by mixer 26. In the elution stage, the washed and loaded lithium ion sieve is contacted with HCl through line 28 to elute lithium ions from the lithium ion sieve. The concentration of acid in the second stirred reactor 22 is maintained at a constant value through the addition of HCl through line 28. The regenerated lithium ion sieve flows through line 30 to another stirred reactor 32 as part of the acid wash stage. Lithium ions, as LiCl product, are separated from the regenerated lithium ion sieve and flow through line 34. The regenerated lithium ion sieve is maintained in suspension by mixer 36. In the acid wash stage, residual acid is transferred to the lithium ion sieve via the addition of water via line 38 to ensure that the feed brine is not acidified in the loading stage when the lithium ion sieve is recycled and that the recovered lithium is not recycled back to the loading stage. washed from The cleaned and regenerated lithium ion sieve flows back into the first stirred reactor 4 through line 40 and is used again in the loading stage. The dilute acid wash is separated from the washed and regenerated lithium ion sieve and flows through line 44 to be used with additional concentrated acid in the elution stage.

In one embodiment, several loading stages may be used in series and operated countercurrently. Brine may initially be treated in a first loading stage. The treated brine from the first loading stage, which still contains some residual lithium, can be passed to the second loading stage, where it is contacted with a lithium ion sieve to further reduce the lithium content of the brine. The lithium ion sieve from the second loading stage, containing some lithium but still having additional lithium capacity available, may be transferred to the first loading stage. The loaded lithium ion sieve from the first loading stage can then be passed to the elution stage. In this way, the lithium content of the spent brine can be further reduced. An additional loading stage may be used in this way to further reduce the lithium content of the spent brine.

The loaded lithium ion sieve can be treated similarly in several elution stages, whereby the lithium ion sieve is delivered countercurrently to the eluent flow. In this way, the lithium content of the lithium ion sieve can be further reduced, and the lithium concentration in the eluent (i.e., lithium product) can be increased.

The exchange reaction for the capture of lithium ions from brine to the lithium ion sieve is represented by the following formula (1).

LIS.H + Li ⁺ → LIS.Li + H ⁺ (1)

In the above formula, LIS.H represents a lithium ion body in the form of newly regenerated hydrogen and LIS.Li represents a lithium ion body in the form of loaded lithium.

As the reaction proceeds, hydrogen ions are released into the brine, reducing the pH of the brine. The active ingredient of the lithium ion sieve may be, for example, an oxide of titanium, such as metatitanic acid (MTA). MTA is a weak acid and therefore has a high affinity for hydrogen ions. Consequently, at low pH, where hydrogen ions are available, MTA may not readily exchange hydrogen ions for lithium. The lithium ion sieve may also further contain small amounts of dopants.

Figure 2 shows the amount of metal ion capture as a function of pH. It can be seen that lithium capture is significantly reduced at pH less than about 6.5 and lithium will hardly be captured at pH less than about 4. As lithium loading progresses, the pH of the brine drops. When the pH drops to a pH of about 4, further entrapment of lithium cannot occur.

This phenomenon is similar to that observed for conventional polymeric weak acid cation exchange resins. A conventional approach to address this problem is to pre-neutralize the ion exchange resin with sodium hydroxide to convert the exchanger to the sodium form, thereby keeping the pH of the solution constant during loading. However, this approach cannot work effectively when using a lithium ion sieve because the sodium ions are too large to penetrate the lithium ion sieve.

In one embodiment, the pH may be adjusted prior to contacting the brine with the LIS by adding NaOH or another base such as sodium carbonate or ammonium hydroxide to the brine prior to treatment. Since this pretreatment raises the initial pH, the final pH will not be so low as to prevent lithium entrapment. However, a disadvantage of this approach is that the amount of sodium ions captured by the lithium ion sieve increases at increased pH levels, as shown in FIG. 2 . Also, when the pH is raised above 8, magnesium hydroxide may precipitate out of solution.

In one embodiment, the brine/lithium ion sieve slurry in the loading reactor may be neutralized with an alkali, such as NaOH, to maintain the pH to maximize lithium entrapment while minimizing sodium entrapment. The pH may be generally greater than about 5 and less than about 9, preferably greater than 6 and less than 8. When the lithium ion body is MTA, the pH is preferably 6 to 7.

Lithium is eluted from the LIS, typically by an acid, such as hydrochloric acid, while the lithium ion body is regenerated and a lithium product is produced, as shown by equation (2) below. The lithium ion sieve effectively neutralizes the acid through this reaction.

LIS.Li + H ⁺ → LIS.H + Li ⁺ (2)

As shown in FIG. 3, the amount of lithium eluted from the lithium ion sieve increases as the concentration of HCl increases. For optimal elution efficiency, the acid concentration can be kept below 0.1 M (defined as mol·dm ⁻³ in FIG. 3 ). As shown in Figure 7, for optimal elution efficiency, the acid concentration may correspond to a pH of less than 3 and greater than 1, preferably a pH of approximately 2.

However, also as shown in FIG. 3, at acid concentrations above 0.1 M, increasing amounts of titanium are extracted from the lithium ion body, thereby degrading the lithium ion body and reducing its useful life. At acid concentrations greater than about 0.1 M, excessive amounts of titanium are extracted, resulting in extremely short lifetimes.

One way to minimize this degradation of the lithium ion sieve is to minimize the contact time of the LIS with the acid. In one embodiment, since the lithium ion sieve is in powder form, the kinetics of the ion exchange process are very fast and most of the exchange reactions of equation (2) above are completed in less than 1 hour. In one embodiment, the contact time of the LIS with the eluting acid is less than 1 hour. Thus, lithium is essentially completely removed from the lithium ion body while degradation of the lithium ion body is minimized.

Additionally, the particle size of the lithium ion sieve particles plays an important role in the design of the systems described herein. Figure 4 shows a typical particle size distribution of a sample of lithium ion metatitanate sieve taken after several hours of air agitation in the slurry. The effective particle size (d ₁₀ ) is about 0.5 μm and 90% of the material (by volume) is in the range of 0.4-40 μm. The effective size is the particle diameter such that 10 percent of the total grains are smaller and 90 percent of the total grains are larger, by weight or volume. The effective size of these materials is about 0.5 μm. While coarser material can settle from an aqueous slurry by gravity in less than 1 hour, finer particles do not settle easily even after 1 day. Without intending to be bound by any particular theory, it is believed that the larger lithium ion sieve particles are aggregates of fine particles produced by sintering during the synthesis process. As a result, large particles will be susceptible to mechanical attrition during mixing with the process liquid, resulting in an increase in the proportion of fine particles over time. As a result, separation of the lithium ion sieve from the process liquid by gravity settling is not ideal.

Membranes are increasingly being used in bioreactors for wastewater treatment. In a typical membrane bioreactor (MBR), microfiltration or ultrafiltration membranes with a pore size of less than 0.1 μm in the form of hollow-fibres, tubes or plates are immersed in a suspension of wastewater and bio-solids. Clear filtered/treated wastewater is drawn through the membrane by vacuum. The wastewater/biosolids slurry is typically agitated by air jets. Air agitation promotes oxygen transfer to the bio-solids and prevents membrane fouling due to accumulation of bio-solids on the membrane surface.

In membrane bioreactors, the suspended solids concentration is typically less than 30 g/L, more typically 10-15 g/L. Higher suspended solids concentrations are not used because oxygen delivery is hindered by the resulting higher non-Newtonian fluid viscosity. In addition, higher suspended solids concentrations decrease membrane flux rates and/or increase transmembrane pressure. Typical flux rates for submerged membranes in membrane bioreactors are 10-30 liters/hour/square meter (this unit is commonly abbreviated "LMH").

In one embodiment, a submerged ultrafiltration or microfiltration membrane process may be used in the present invention as a means of separating the lithium ion sieve from the process liquid. The pore size of the membrane is smaller than the smallest lithium ion sieve particle, typically less than about 1 μm, so that nearly 100% solids separation can be achieved. In the present invention, oxygen delivery is not a problem. However, immersion aeration (air agitation) can provide the necessary slurry mixing, while rising bubbles wipe the membrane surface to reduce membrane fouling and reduce attrition and shear of the LIS particles compared to mechanical mixing.

The embodiments described herein differ significantly from typical submerged membrane applications such as MBR. Lithium ion sieve particles allow processing of much higher suspended solids concentrations while achieving much higher fluxes. Fluxes obtained in conventional MBR applications are typically less than 30 LMH at transmembrane pressures of 10-30 kPa and total suspended solids (TSS) levels of less than 30 g/L. In contrast, when using the present invention, fluxes as high as 300 LMH at a transmembrane pressure of 20 kPa have been obtained with lithium ion sieves at TSS levels greater than 100 g/L.

According to the present invention, the suspended solids concentration may be greater than about 50 g/L, preferably greater than 100 g/L. Without intending to be bound by any particular theory, a higher solids concentration in the reactor is believed to be advantageous because it reduces the reactor volume required to achieve a given lithium ion body-liquid contact time.

In a fixed bed ion exchange system, the acid eluent lowers in acid concentration as it passes through the bed and is neutralized by the reaction given by equation (2) above. To maintain elution efficiency, the pH of the acid entering the bed may be much lower than 1 to keep the pH of the acid in contact with the lithium ion sieve below 3. As a result, when the lithium ion sieve is regenerated in the fixed bed, the lithium ion sieve toward the entry end of the bed will be severely deteriorated by the more concentrated acid.

According to the present invention, the lithium ion sieve can be regenerated as a slurry in a reactor vessel where the lithium ion sieve is contacted with a uniform concentration of acid. The acid concentration may be maintained at a concentration of less than 0.1 M, preferably an acid concentration corresponding to a pH of less than 3 and greater than 1, preferably a pH of approximately 2. This concentration can be maintained by continuously measuring the acid concentration of the liquid in the reactor using suitable means and adding as much concentrated acid as necessary to maintain the concentration in the desired range (e.g., pH = 2).

In order to minimize impurities such as calcium, magnesium, potassium, and sodium in the final lithium salt product produced by acid elution of a lithium ion sieve, residual feed brine is added to the loaded lithium ion sieve after loading and prior to acid elution. It can be removed from the lithium ion sieve by mixing with water and then separating the water. In an alternative embodiment, residual feed brine may be removed by filtering the loaded lithium ion sieve directly through a suitable filter. According to the present invention, the preferred particle size of the lithium ion sieve is in the range of 0.4-40 μm. Solid particles in this range can be filtered and dewatered by conventional solid/liquid separation devices using filter media such as woven filter cloths with openings greater than 10 μm instead of membranes with pore sizes less than 1 μm. . Thus, most of the feed brine will be separated from the loaded lithium ion sieve. The dehydrated lithium ion sieve can then be washed directly on the filter to remove residual brine from the lithium ion sieve without the need to re-slurry the lithium ion sieve in water. Exemplary types of filters include, but are not limited to, horizontal belt vacuum and pressure filters, rotating drum vacuum and rotating disk vacuum and pressure filters, pressure filter presses, and centrifuges.

As discussed above, elution of lithium from the lithium ion sieve using an acid yields an acidic lithium salt solution. To minimize the return of recovered lithium back to the loading reactor with the regenerated lithium ion sieve, the lithium ion sieve is preferably separated from the acidic lithium salt eluent solution. A similar approach to that used to separate the feed brine from the loaded lithium ion sieve may be used. Thus, the regenerated lithium ion sieve can be mixed with water and then separated from the water. Alternatively, the lithium ion sieve may be filtered through a suitable filter, preferably one having water washability.

Care should be taken to minimize the moisture content of the lithium ion sieve delivered to the regeneration reactor. If an excessive amount of water enters the regeneration reactor with the lithium ion sieve, the recovered lithium salt eluent solution will be too dilute. Similarly, lithium will be recovered along with the liquid entrained on the loaded lithium ion sieve exiting the regeneration reactor.

As shown in Example 1 below, the working capacity of the lithium metatitanate sieve can be about 0.01 g of lithium per gram of lithium ion sieve. Then the flow rate of the lithium ion sieve on a dry basis would be 100 g lithium ion sieve/g Li recovered. The slurry in the loading reactor has a suspended solids concentration of 100 g/L (i.e., about 90 wt% moisture and about 10 wt% solids; 1 liter of water per 100 grams of lithium ion sieve), and this slurry is passed directly to the regeneration reactor. If it is, it will bring (1 g lithium ion sieve/0.01 g Li/100 g/L lithium ion sieve) = 1.0 liters of water per gram of lithium recovered. Ignoring the water contained in the concentrated acid, then the concentration of lithium in the eluent will be 1 g/l.

Also, when the concentration of suspended solids in the regeneration reactor is maintained at 100 g/L and discharged at this concentration, the amount of lithium entrained with the regenerated lithium ion sieve is (1 liter/g Li x 1 g/L Li) = 1 will be g Li/g Li recovered. In other words, all lithium eluted from the lithium ion sieve will be released by the lithium ion sieve. Then, if this lithium ion body is recycled directly back to the loading reactor, net lithium will not be recovered.

The regenerated lithium ion sieve slurry may be mixed with water in a wash reactor to restore the lithium value prior to recycling the lithium ion sieve to the loading reactor. Separating 90% of the lithium from the lithium ion sieve would require 9 liters of water per gram of lithium recovered. The dilute liquid in the wash reactor can then be separated by gravity or a membrane, for example. Then the concentration of lithium will be only 0.1 g/l. However, these concentrations are too low to be used in practice. Thus, the lithium ion sieve must be dehydrated to a water content well below 90%.

For example, if a loaded lithium ion sieve slurry is dehydrated to 50% moisture (i.e., 1 liter water/1000 g lithium ion sieve), the lithium ion sieve is only (1 liter water/1000 g lithium ion sieve)/ (0.01 g Li/g lithium ion sieve) = will carry 0.1 liter of water per gram of Li recovered. Ignoring the water contained in the concentrated acid, then the concentration of lithium in the eluent would be 10 g/liter.

Also, the regenerated lithium ion sieve must be dehydrated when it is removed from the regeneration reactor. Otherwise, a large portion of the recovered lithium will be recycled back to the loading reactor together with the lithium ion sieve. Even if the regenerated lithium ion sieve is highly dehydrated, lithium lost as moisture entrained in the lithium ion sieve can be a problem. For example, when the regenerated lithium ion sieve is dehydrated to a water content of 50% by weight (i.e., 1 liter of water per 1000 g of lithium ion sieve), the amount of lithium entrained with the lithium ion sieve is (1 liter/1000 g of lithium ion sieve)/(0.01 g Li/g lithium ion sieve) x 10 g Li/1L) = 1 g Li/g Li recovered. In other words, all lithium eluted from the lithium ion sieve will be released by the lithium ion sieve. Then, when this lithium ion body is recycled back to the loading reactor, no pure lithium will be recovered.

Thus, lithium from the liquid entrained with the dehydrated lithium ion sieve must be recovered. For example, a regenerated lithium ion sieve can be washed with water. Lithium will then be recovered from the wash water. The amount of wash water should be sufficient to recover most of the lithium, but not so great as to over-dilute the recovered lithium salt solution. One way to accomplish this would be to re-slurry the lithium ion sieve in water and then re-filter the lithium ion sieve from the slurry. To wash 90% of the lithium from the Li-ion sieve, about 9 mL of water is required per mL of liquid entrained in the Li-ion sieve, which allows recovery of a lithium salt solution containing 1 g/L lithium under these conditions. something to do.

By using two or more countercurrent washes, the amount of wash water can be reduced and the lithium concentration can be increased at the same time. Thus, the dehydrated lithium ion sieve recovered from the first washing stage is once again re-slurried in water in the second washing stage and then dewatered again. The wash water recovered from the second stage dewatering unit is used in the first wash stage instead of clean water. When using two countercurrent washing stages, the amount of water required for 90% lithium recovery can be reduced from about 9 mL of water per mL of entrained liquid to about 3 mL of water per mL of entrained liquid and The concentration can be increased from 1 g/L to about 3 g/L.

In a further embodiment, the slurry may be dewatered by a device such as a horizontal vacuum belt filter. The dewatered lithium ion sieve cake can then be washed directly on the filter. One or more countercurrent washing stages may be used on the filter. As another option, a centrifuge may be used. If a centrifuge is used, the solids can be re-slurried in water and then dewatered by the centrifuge. If multiple washing stages are used, the dewatered solids from the first centrifuge can be re-slurried back with water and then dewatered in the second centrifuge. The liquid discharged from the second centrifuge may be used as water to slurry the solids supplied to the first centrifuge. An additional centrifuge can be used in this way to effectively achieve multi-stage countercurrent solids washing.

When the particle size of the lithium ion sieve is too small, this dehydration becomes more difficult. Indeed, even when most of the particles are greater than 10 microns in diameter, the presence of particles much smaller than 10 microns in diameter makes dewatering difficult. In particular, when the average particle size of the ion sieve is 0.1 μm or less, dehydration becomes virtually impossible.

In another embodiment of the present invention, the dry lithium ion sieve may be classified by a suitable device such as an air classifier, or the wet lithium ion sieve may be sieved to remove fine particles having a diameter of less than 1-10 micrometers. It can be classified by elutriation. By doing so, separation of the lithium ion sieve from the liquid to be treated is facilitated. Removal of the fine particles will significantly improve the filtration rate, avoid clogging of the filter media, and result in a filter cake with a lower moisture content. By removing fine particles in this way, conventional solid/liquid separation devices such as horizontal belt vacuums and pressure filters, rotating drum vacuums and rotating disk vacuums and pressure filters, pressure filter presses, centrifuges, and the like can be used more effectively.

To maximize the purity of the recovered lithium salt product, the feed brine must be efficiently separated from the loaded lithium ion sieve. For example, the purity requirements for battery grade lithium carbonate are very stringent. Any residual feed brine retained in the loaded lithium ion sieve will contaminate the product with impurities in the feed brine, such as calcium, magnesium, sodium, potassium, and the like. Since the concentration of these impurities in brine is much higher than lithium, even minimal brine carry-over is a problem. In practice, the contribution of impurities from the entrained brine on the loaded lithium ion sieve is potentially greater than the amount of impurities actually exchanged onto the lithium ion sieve in most cases. Additional processes, such as lime/soda and ion exchange softening, can be used to purify the recovered lithium solution, but these additional process steps entail additional capital and operating costs. However, efficient dewatering and washing of the loaded lithium ion sieve prior to delivery to the regeneration reactor can minimize the need for these costly processes. As discussed above, if the lithium ion sieve does not have a significant amount of particles less than 1-10 microns in diameter, efficient dewatering can be achieved using conventional solid/liquid separation devices. Additionally, wash water requirements can be reduced by using multi-stage countercurrent washing.

The present invention will hereinafter be described with reference to exemplary embodiments, which are intended to be understood as examples only and are not intended to limit the scope of the present application.

Example

A test unit was constructed to demonstrate a method according to one embodiment of the present invention. A schematic diagram of the test unit is shown in FIG. 5 .

The test unit consisted of six reactors (R1-R6), each equipped with an air agitated diffuser and five of them with submerged membrane modules. Reactor R4, used for acid regeneration of the lithium ion sieve, was not equipped with a membrane. The working volume of each reactor was approximately 5 liters, except for reactor R4, which had a working volume of approximately 1.1 liters.

Lithium titanate (LTO) was used as the lithium ion sieve. LTO was synthesized by reacting lithium hydroxide with titanium dioxide at a molar ratio of approximately 2.2:1 at a temperature of 700° C. for 4 hours. Figure 4, discussed above, provides the particle size distribution of the LTO used in this example. LTO was converted to HTO by acid washing the initial LTO produced through synthesis in 0.2 N HCl for 16 hours and then washing the produced metatitanic acid (HTO) with water. Reactors R1 and R2 were initially charged with 100 g/L of an aqueous slurry of LIS, while the remaining reactors were initially charged with 500 g/L of a slurry of LIS. The lithium ion sieve was conveyed from the reactor to the reactor using a peristaltic pump as a slurry. The flow rate of the lithium ion sieve slurry was adjusted so that the solids transfer rate was approximately 100 g/h on a dry weight basis.

The membrane modules were laboratory-scale submerged POREFLON™ units manufactured by Sumitomo Electric Corporation, each having an effective membrane area of 0.1 m 2 . The liquid was drawn through the membrane using a vacuum with a peristaltic pump. The vacuum was maintained below 40 kPa.

The lithium-containing brine was made from brine obtained from the Smackover Formation in Southern Arkansas and had the composition shown in Table 1 below. After lithium was extracted from the brine according to the process, the brine was re-reinforced with lithium chloride and recycled to the process. As a result, the lithium concentration in the feed brine was somewhat higher than in the initial brine as received. Sodium and potassium concentrations were estimated based on published saline analysis.

<Table 1>

^* Estimated from published brine analysis data.

The loading reactor, reactor R1, was equipped with a pH controller that automatically controlled the addition of 1 N NaOH to maintain a pH of 7.8. Thus, the acid generated by the ion exchange reaction was continuously neutralized. Feed brine was introduced into the reactor (R1) and contacted with HTO. HTO was supplied from reactor R6 to reactor R1 as a 500 g/L slurry. As a result of mixing the concentrated slurry from reactor R6 with the feed brine, the solids concentration of the lithium ion sieve in reactor R1 was about 100 g/L. As the HTO extracted lithium ions from the brine, the HTO was partially converted back to LTO. Lithium-depleted (ie, exhausted) brine was drawn through the membrane by a pump.

The loaded lithium ion sieve (i.e., LTO) was withdrawn from reactor R1 as a brine slurry and directed to reactor R2, which is a brine wash reactor. Water was supplied to the reactor (R2) to wash residual brine from the LTO. Wash water was withdrawn from reactor R2 through another submerged membrane module.

The loaded/washed LIS was withdrawn from the reactor (R2) as an aqueous slurry and directed to the thickening reactor, the reactor (R3). As water was withdrawn from reactor R3 through another submerged membrane module, the solids concentration in reactor R3 was increased to approximately 500 g/L.

A thickened slurry of loaded/washed LIS at a solids concentration of about 500 g/L was withdrawn from reactor R3 and directed to reactor R4, which is a regeneration reactor. The lithium ion sieve in reactor R4 was contacted with hydrochloric acid at a concentration of approximately 0.2 M. The lithium ion sieve solids concentration in reactor R4 was approximately 500 g/L. The acid concentration was monitored and maintained at a constant level by a conductivity controller at a conductivity set point of 150 mS/cm through the addition of 5 M HCl. When the lithium ion sieve was contacted with acid, it was converted from the LTO form back to the HTO form and a lithium ion sieve slurry of lithium chloride and about 0.2 M hydrochloric acid was produced. Reactor R4 was not equipped with a membrane, and the lithium ion sieve slurry of HCl/lithium chloride was simply allowed to overflow into reactor R5. An acid concentration of 0.2 M is recognized as undesirable due to excessive dissolution of the titanium from the LIS, but this example still illustrates the method of the present invention.

Reactor R5 was the first of two acid wash reactors operated countercurrently. Most of the HCl/lithium chloride was washed from the lithium ion sieve in reactor R5, while most of the residual HCl/lithium chloride was washed from the lithium ion sieve in reactor R6. The lithium ion sieve in reactor R5 was contacted with wash water from reactor R6 at a solids concentration of about 500 g/L. The acid wash water was withdrawn from the reactor (R5) through another submerged membrane module. The acid wash water discharged from reactor R5 constituted the lithium chloride product recovered from the process. A slurry of lithium ion sieve at a concentration of about 500 g/L was withdrawn from reactor R5 and directed to reactor R6.

Fresh water added to reactor R6 washed most of the remaining HCl/lithium chloride from the lithium ion sieve. Wash water was withdrawn from reactor R6 through another submerged membrane module and directed to reactor R5. This reduced the concentration of lithium chloride in the wash water in reactor R6 to less than 10% of the concentration of lithium in reactor R4. The lithium ion sieve/wash water slurry was withdrawn from reactor R6 and directed back to reactor R1, where it was reused to extract lithium from the feed brine.

Continuous 12 hour test runs were performed. Aliquots of exhausted brine and product were sampled and analyzed hourly. A graph showing brine and product concentrations consumed over the course of the run is shown in FIG. 6 . The results summarized in Table 1 were obtained from a 1 hour composite sample taken after 10 hours of operation. The lithium concentration was reduced from 244 mg/L to 61 mg/L with 75% recovery. The liquid residence time in the loading reactor was about 1 hour.

The lithium product had a lithium concentration of 4,300 mg/L. More lithium was removed from the product (2,322 mg/h) than was actually extracted from the brine (957 mg/h). Without intending to be bound by any particular theory, it is believed that the difference (1,365 mg/h) is probably residual lithium on the lithium ion sieve that was not completely removed from the LTO during the initial HCl pickling. Based on the lithium actually extracted from the brine, the lithium ion sieve capacity was 9.6 mg/g. The liquid residence time in the strip reactor was 2.2 hours. Based on the loaded and recovered lithium, the lithium concentration factor was about 10 times.

The feed brine had a calcium concentration of 22,000 mg/L, while the product had a calcium concentration of only 1,400 mg/L. The ratio of calcium to lithium in the feed was 90. The ratio in the product was 0.33. However, only about half of the lithium in the product was actually extracted from the brine. When only lithium in the product extracted from the brine was considered, the ratio of Ca to Li in the product was 0.62, indicating an enrichment factor of 90/0.62 = 145.

The feed brine had an estimated sodium concentration of 43,000 mg/L, while the product had a sodium concentration of only 9,770 mg/L. The sodium to lithium ratio in the feed was 176. The ratio in the product was 2.3. When only lithium in the product extracted from the brine is considered, the ratio of Na to Li in the product is 4.3, indicating an enrichment factor of 176/4.3 = 41.

The feed brine had a magnesium concentration of 2,170 mg/L, while the product had a magnesium concentration of only 76 mg/L. The ratio of magnesium to lithium in the feed was 8.9. The ratio in the product was 0.018. When only lithium in the product extracted from the brine was considered, the ratio of Mg to Li in the product was 0.034, indicating an enrichment factor of 8.9/.034 = 262.

Thus, the systems and methods described herein have the ability to selectively recover lithium from brine containing high concentrations of calcium, sodium, and magnesium.

In this example, only one brine wash reactor was used, so some brine was passed to the regeneration reactor on the loaded lithium ion sieve, and some calcium, sodium, and/or magnesium was transferred to the regeneration reactor on the loaded lithium ion sieve. will carry Without intending to be bound by any particular theory, it is believed that the results could be improved by including a second brine wash reactor. Also, as discussed above, by lowering the loading pH to 6-7, the amount of sodium loaded on the lithium ion sieve could be reduced without significantly reducing the lithium capacity.

comparative example

A major test was performed by Chitraka to evaluate the effect of HCl concentration on the initial extraction of lithium and titanium from the adsorbent, and is shown in Figure 4a of Chitraka. Figure 4a of Chitraka shows the amount of lithium and titanium extracted as a function of HCl concentration. Chitraka's data show that the HCl concentration should be above 0.2 M. Indeed, Fig. 4a of Chitraka does not provide data for lithium extraction from the adsorbent at acid concentrations below 0.1 M, which is the preferred acid concentration at which the present invention operates. In the present invention, the lithium and titanium components of the LTO adsorbent are extracted at much lower acid concentrations than predicted by Chitraka.

References herein to terms such as "vertical", "horizontal", etc. are made by way of example and not limitation, in order to establish a frame of reference. It is understood that various other frames of reference may be used to describe the present invention without departing from the spirit and scope of the present invention. It is also understood that features of the invention are not necessarily drawn to scale in the drawings. Moreover, so far as the terms "consisting of", "comprises", "having", "has", "having", or variations thereof are used in the description or claims, such terms shall be used in a manner similar to the term "comprising". It is intended to be both inclusive and open.

References herein to terms modified by approximation language such as “about,” “approximately,” and “substantially” should not be limited to the exact value specified. Approximation language may correspond to the precision of the instrument used to measure the value and, unless otherwise dependent on the precision of the instrument, may represent +/- 10% of the stated value(s).

A feature “connected” or “coupled” to or with another feature may be directly connected or coupled to or with another feature, or alternatively, there may be one or more intervening features. . In the absence of intervening features, a feature may be “directly connected” or “directly coupled” to or to another feature. Where at least one intervening feature is present, the feature may be “indirectly connected” or “indirectly coupled” to or to another feature. A feature “on” or “contacting” another feature may be directly on or in direct contact with another feature, or, instead, there may be one or more intervening features. In the absence of intervening features, the feature may be “directly on” or “directly in contact” with another feature. Where at least one intervening feature is present, the feature may be “indirectly on” or “indirectly in contact with” another feature.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. . The terms "comprises" and/or "comprising" when used herein indicate the presence of the stated features, integers, steps, operations, elements, and/or components, but also indicate the presence of one or more other features, It will be further understood that the presence or addition of integers, steps, actions, elements, components, and/or groups thereof is not excluded.

Although the present invention has been illustrated by the description of various embodiments and these embodiments have been described in great detail, it is not Applicant's intention to limit the scope of the appended claims to these details or to limit in any way. Additional advantages and modifications will readily appear to those skilled in the art. Accordingly, the invention in its broader aspects is not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. In order to enable those skilled in the art to fully make and use the claimed invention, Applicants have provided information regarding both advantages and disadvantages of various detailed embodiments. One skilled in the art will appreciate that in some applications, the disadvantages of specific embodiments as detailed above may be completely avoided or outweighed by the full advantages provided by the present invention as claimed. Accordingly, new endeavors may be made from the above detailed teachings without departing from the spirit or scope of the applicant's general inventive concept.

Claims (30)

A method for recovering lithium ions from lithium-containing brine, comprising:
contacting the lithium-containing brine with the lithium ion sieve for less than about 1 hour in a first reactor to form a lithium ion complex with the lithium ion sieve; and
Decomplexing lithium ions from the lithium ion sieve in a second reactor to form an acidic lithium salt eluent solution separated from the lithium ion sieve.
contains;
wherein the lithium ion body comprises an oxide of titanium or niobium;
Here, the pH of the first reactor is maintained at a constant value through the addition of alkali.
method. 2. The method of claim 1, wherein the decomplexation is effected via elution with an acid. 3. The method of claim 2, wherein the concentration of the acid is maintained at a constant value through the addition of the acid. 4. The method according to claim 2 or 3, wherein the concentration of the acid is less than 0.1 M. 5. The method according to any one of claims 2 to 4, wherein the pH of the acid is greater than 1 and less than 3. 5. The method of any one of claims 2-4, wherein the pH of the acid is approximately 2. 7. The method according to any one of claims 1 to 6, wherein the pH is maintained at a constant value above 4 and below 9. 8. The process of any one of claims 1 to 7, wherein the pH in the first reactor is greater than 6 and less than 8. 9. The method of any one of claims 1 to 8, wherein greater than 90% of the lithium ion sieves have an average particle diameter of less than 40 μm and greater than 90% of the lithium ion sieves have an average particle diameter of greater than 0.4 μm. way of being. 10. The method according to any one of claims 1 to 9, wherein greater than 90% by volume of the particles of the lithium ion sieve are less than 100 μm in diameter and greater than 0.5 μm in diameter. 10. The method according to any one of claims 1 to 9, wherein greater than 90% by volume of the particles of the lithium ion sieve are greater than 0.5 μm in diameter. 12. The method according to any one of claims 1 to 11, wherein the lithium ion body comprises metatitanic acid. According to any one of claims 1 to 12,
separating the lithium ion complex with the lithium ion sieve from the brine using a solid/liquid separation device; and
Contacting the lithium ion complex with the lithium ion sieve with water prior to decomplexing in a second reactor.
How to further include. According to any one of claims 1 to 13,
using a solid/liquid separation device, separating the lithium ion sieve from the acidic lithium salt eluent solution;
contacting the lithium ion sieve with water after decomplexing in the second reactor to obtain a regenerated lithium ion sieve and dilute acid wash water; and
Adding the regenerated lithium ion sieve to the first reactor.
How to further include. 15. The method of claim 14, further comprising adding dilute acid wash water and additional concentrated acid to the second reactor. 16. The method according to any one of claims 1 to 15, wherein the average contact time of the acid and the lithium ion complex with the lithium ion sieve is less than 1 hour. 17. The process according to any one of claims 1 to 16, wherein the first reactor comprises an ultrafiltration or microfiltration membrane. 18. The method of any one of claims 1 to 17, wherein air is used to agitate the contents of the first reactor. 19. The method of any one of claims 1 to 18, wherein the concentration of the lithium ion sieve is greater than 50 g/L. 18. The method of claim 17, wherein the flux rate through the ultrafiltration membrane or microfiltration membrane is greater than 30 LMH at a transmembrane pressure of less than 30 kPa. 21. The method of any preceding claim, further comprising removing the lithium ion sieve having an average particle diameter of less than 1 μm prior to contacting the lithium-containing brine with the lithium ion sieve. 15. The method of claim 14, further comprising dewatering the lithium ion complex with the lithium ion sieve to a moisture content of less than 90% by weight prior to decomplexing the lithium ions from the lithium ion sieve in the second reactor. 15. The method of claim 14, further comprising dewatering the regenerated lithium ion sieve prior to adding it to the first reactor. 15. The method of claim 13 or 14, wherein contacting the lithium ion sieve with water results in greater than 50% of the lithium ions decomplexed from the lithium ion sieve being lithium prior to adding the regenerated lithium ion sieve to the first reactor. and contacting the lithium ion sieve with sufficient water to be washed from the ionic sieve. 25. The method of claim 24, wherein contacting the lithium ion sieve with water causes greater than 50% of the lithium ions decomplexed from the lithium ion sieve to the lithium ion sieve prior to adding the regenerated lithium ion sieve to the first stirred reactor. and contacting the lithium ion sieve with water in more than one countercurrent stage to be washed from the sieve. 26. The method of any preceding claim, wherein the alkali comprises sodium hydroxide, ammonium hydroxide, anhydrous ammonia, potassium hydroxide, sodium carbonate, magnesium hydroxide, or calcium hydroxide. 7. The method according to any one of claims 2 to 6, wherein the acid comprises hydrochloric acid or sulfuric acid. 28. The method of any preceding claim, wherein the concentration of the lithium ion sieve is greater than 100 g/L. 29. The process of any one of claims 1-28, wherein the alkali comprises anhydrous ammonia or ammonium hydroxide. 30. The method of any one of claims 1 to 29, wherein the lithium-containing brine and/or lithium ion complex is incubated for about 5 to about 59 minutes, about 15 to about 59 minutes, about 25 to about 59 minutes, about 30 to about 30 minutes. contacting the lithium ion sieve for a time selected from the group consisting of 55 minutes, about 40 to about 55 minutes, and about 45 to about 55 minutes.

Images