Patent Description:
Seawater contains about <NUM>/kg, and subsurface brines may contain up to <NUM>,<NUM>/kg, more than four orders of magnitude greater than sea water. Typical commercial lithium concentrations are between <NUM> and <NUM>,<NUM>/kg. In <NUM>, subsurface brines yielded about half of the world's lithium production.

The Salton Sea Known Geothermal Resource Area ("SSKGRA") has the most geothermal capacity potential in the United States. Geothermal energy, the harnessing of heat radiating from the beneath the Earth's crust, is a renewable resource that is capable of cost-effectively generating large amounts of power. In addition, the SSKGRA has the potential to become North America's prime sources of alkali metals, alkaline earth metals and transition metals, such as lithium, potassium, rubidium, iron, zinc and manganese.

Brines from the Salton Sea Known Geothermal Resource Area are unusually hot (up to at least <NUM> at <NUM> depth), hypersaline (up to <NUM> wt. %), and metalliferous (iron (Fe), zinc (Zn), lead (Pb), copper (Cu)). The brines are primarily sodium (Na), potassium (K), calcium (Ca) chlorides with up to <NUM> percent of total dissolved solids. While the chemistry and high temperature of the Salton Sea brines have led to the principal challenges to the development of the SSKGA, lithium and other brine elements typically maintain high commodity value and are used in a range of industrial and technological applications.

The "lithium triangle" of Chile, Argentina and Bolivia is where approximately <NUM>% of the world's lithium comes from. Chile is currently the second largest producer of lithium carbonate and lithium hydroxide, which are key raw materials for producing lithium-ion batteries, behind only Australia. Salar de Atacama is one of the hottest, driest, windiest and most inhospitable places on Earth, and the largest operations are in the shallow brine beneath the Salar de Atacama dry lakebed in Chile, which as of <NUM>, yielded about a third of the world's supply. The Atacama in Chile is ideal for lithium mining because the lithium-containing brine ponds evaporate quickly, and the solution is concentrated into high-grade lithium products like lithium carbonate and lithium hydroxide. Mining lithium in the salars of Chile and Argentina is much more cost-effective than hard rock mining where the lithium is blasted from granite pegamite orebodies containing spodumene, apatite, lepidolite, tourmaline and amblygonite. The shallow brine beneath the Salar de Uyuni in Bolivia is thought to contain the world's largest lithium deposit, often estimated to be half or more of the world's resource; however, as of <NUM>, no commercial extraction has taken place, other than a pilot plant. The mining of lithium from brine resources in the "lithium triangle" historically depends upon easy access to large amounts of fresh water and very high evaporation rates. With declining availability of fresh water and climate change, the economic advantage of conventional processing techniques is disappearing.

Fixed-bed and continuous countercurrent ion exchange ("CCIX") systems have been used to recover metals, such as nickel (Ni) and cobalt (Co), from ore leach solutions. While fixed-bed systems are generally used in recovery projects, they are known to require relatively large amounts of water and chemicals and the performance is generally weaker than CCIX systems.

Utilizing CCIX-type equipment in the adsorption of lithium from brines with lithium selective adsorbents in a CCAD circuit will bring increased process efficiency versus classical fixed-bed processing. The water and reagent efficiency of a CCAD circuit/process should be a preferred replacement for evaporation ponds in the brine mining operations in the salars of "lithium triangle", saving millions of acre feet of water from evaporative loss.

It is therefore desirable to provide an improved process for selective adsorption and recovery of lithium from natural and synthetic brines.

It is further desirable to provide a continuous countercurrent adsorption and desorption process for the selective recovery of lithium from natural and/or synthetic brines, which are normally considered economically non-viable using conventional membranes, solvent extraction, or fixed-bed arrangements of lithium selective adsorbent technologies.

It is still further desirable to provide a process for recovering lithium from a natural or synthetic brine solution by treating the brine solution with a lithium selective adsorbent in a CCIX-type system using a CCAD process. <CIT> discloses a method for adsorption/desorption of lithium ions, which employs a counter current decantation (CCD) process in adsorption/desorption of lithium ions.

<CIT> discloses a fluid treating device, containing a number of vessels through which the fluid is led, at least two feed pipes and at least two discharge pipes and a distributing device to control the flow of fluid from the feed pipes through the vessels and to the discharge pipes.

Before proceeding to a detailed description of the invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or embodiments) shown and described. Those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the claims.

In general, in a first aspect, the invention relates to a process for selective recovery of lithium from a feed brine solution. The process includes concentrating the lithium in the brine solution by cyclically and sequentially flowing the brine solution through a continuous countercurrent adsorption and desorption circuit to form an enhanced lithium product stream, and recovering the lithium from the enhanced lithium product stream.

The process can also include the steps of removing impurities from the brine solution to form a polished brine solution, and then concentrating the lithium in the polished brine solution by cyclically and sequentially flowing the polished brine solution through a continuous countercurrent adsorption and desorption circuit to form an enhanced lithium product stream. Lithium is then recovered from the enhanced lithium product stream.

The process can also include the step of obtaining the brine solution having lithium chloride. The lithium chloride in the brine solution can be concentrated using the continuous countercurrent adsorption and desorption circuit to form the enhanced lithium product stream, and then, the lithium chloride can be selectively converted to lithium carbonate, lithium hydroxide, or both.

The continuous countercurrent adsorption desorption circuit has a plurality of process zones, with each of the process zones having an adsorbent bed or column containing a lithium selective adsorbent. The lithium selective absorbent can be a lithium alumina intercalate prepared from hydrated alumina, a lithium aluminum layered double hydroxide chloride, a layered double hydroxide modified activated alumina, a layered double hydroxide imbibed ion exchange resin or copolymer or molecular sieve or zeolite, layered aluminate polymer blends, a lithium manganese oxide, a titanium oxide, an immobilized crown ether, or a combination thereof. The process zones can include a brine displacement zone positioned upstream with respect to fluid flow of a brine loading zone, which is positioned upstream with respect to the fluid flow of and in fluid communication with an entrainment rejection zone, which is positioned upstream with respect to fluid flow of and in fluid communication with an elution zone, which is in fluid communication with the brine displacement zone. The brine solution is passed through the loading zone for a predetermined amount of contact time.

The process can also include dewatering the enhanced lithium product stream using a membrane separation, such as reverse osmosis or nano-filtration, in order to produce a high lithium concentration, enhanced lithium product stream and a recycle eluant solution. The enhanced lithium product stream, the high lithium concentration, enhanced lithium product stream or both can then be passed or provided to a lithium solvent extraction and electrowinning process, a solvent extraction and membrane electrolysis process, or a recovery process for production of high purity lithium hydroxide and lithium carbonate for battery production.

The brine solution can be a natural brine, a synthetic brine, or a combination thereof, such as a continental brine, a geothermal brine, an oil field brine, a brine from hard rock lithium mining, or a combination thereof.

In general, in a second aspect, the invention relates to a continuous countercurrent adsorption desorption circuit configured for the selective adsorption and recovery of lithium from a lithium-rich brine solution. The circuit has a plurality of process zones, with each of the process zones comprising a plurality of adsorbent beds or columns having a lithium selective adsorbent. The process zones include a brine displacement zone positioned upstream with respect to fluid flow of a brine loading zone, which is positioned upstream with respect to the fluid flow of and in fluid communication with an entrainment rejection zone. The entrainment rejection zone is positioned upstream with respect to fluid flow of and in fluid communication with an elution zone, and the elution zone in fluid communication with the brine displacement zone.

The lithium-rich brine solution can be a natural brine, a synthetic brine, or a combination thereof, such as a continental brine, a geothermal brine, an oil field brine, a brine from hard rock lithium mining, or a combination thereof. The lithium selective absorbent may be a lithium alumina intercalate prepared from hydrated alumina, a lithium aluminum layered double hydroxide chloride, a layered double hydroxide modified activated alumina, a layered double hydroxide imbibed ion exchange resin or copolymer or molecular sieve or zeolite, layered aluminate polymer blends, a lithium manganese oxide, a titanium oxide, an immobilized crown ether, or a combination thereof.

In a further aspect, the invention relates to a continuous adsorption and desorption process for recovery of lithium from a feed brine solution. An eluant solution passes through an elution zone and strips most of the lithium from the lithium loaded adsorbent. A portion of the lithium product solution is captured as the purified lithium concentrate, and a second portion is employed to displace latent brine from freshly loaded adsorbent. A portion of the lithium product solution along with the displaced brine is routed to the brine feed inlet and this recirculation of lithium via the displacement stream increases the effective lithium concentration in the brine feed stream. The brine feed solution, along with the recycled product and displaced brine, passes through a plurality of adsorbent beds containing lithium selective adsorbent such that lithium is selectively loaded onto the adsorbent and produces a lithium-depleted brine raffinate. A portion of the lithium-depleted brine raffinate is introduced to the elution zone, displacing latent eluant solution so it is not lost to raffinate when the first adsorbent bed in the elution zone eventually transitions from the elution zone to the loading zone. In addition, the process can include membrane dewatering of the lithium product eluate to concentrate the product lithium and replenish the low concentration lithium eluant solution.

The foregoing has outlined in broad terms some of the more important features of the invention disclosed herein so that the detailed description that follows may be more clearly understood, and so that the contribution of the instant inventors to the art may be better appreciated. The instant invention is not to be limited in its application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. Rather, the invention is capable of other embodiments and of being practiced and carried out in various other ways not specifically enumerated herein. Finally, it should be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting, unless the specification specifically so limits the invention.

These and further aspects of the invention are described in detail in the following examples and accompanying drawings.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings, and will herein be described hereinafter in detail, some specific embodiments of the instant invention. It should be understood, however, that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments so described.

This invention relates generally to a process for selective adsorption and recovery of lithium from natural and synthetic brines using CCAD. While the invention is particularly suited for geothermal brines, the source of the feed brine is not so limited. The feed brine source can be from any lithium brine deposit, such as continental sources, geothermal sources, oil field sources, or brine from hard rock lithium mining activity. The feed brine may be subject to a variety of preliminary treatment steps including the removal of solids and certain problem metals or metals of commerce (e.g., iron, manganese, zinc, silicon, etc.). Just prior to treatment by the inventive process, the feed brine preferably has a pH between about <NUM> and about <NUM>. The feed brine generally includes large quantities of chloride salts of sodium, potassium, and calcium. Higher temperature brines (about <NUM> to about <NUM>) improve the kinetic response of the lithium selective adsorbent; however, lower temperature brines can also be successfully treated (about <NUM> to about <NUM>) using the inventive process.

As generally illustrated in <FIG>, existing power plant operations <NUM> generally involve a liquid brine flow from geothermal production wells <NUM> that is partially flashed into steam due to pressure losses as the liquid brine makes its way up the production well casing. The two-phase mixture of brine and steam is routed to a high-pressure separator <NUM> where the liquid brine and high pressure steam are separated. High pressure steam <NUM> is routed from the separator <NUM> to a centrifugal type steam scrubber (not shown) that removes brine carryover from the steam, and from there the scrubbed high pressure steam <NUM> is routed to the turbine generator <NUM>. The liquid brine from the high-pressure separator <NUM> is flashed into a standard-pressure crystallizer <NUM>, and the standard pressure steam <NUM> from the standard-pressure crystallizer <NUM> is passed through a steam scrubber (not shown) and then the scrubbed standard pressure steam <NUM> is routed to the turbine <NUM>. Precipitated solids from the clarifiers are mixed with the brine in the standard-pressure crystallizer <NUM> and contact with the scaling materials, which reduces the scaling tendency in brine significantly.

A brine slurry mixture from the standard-pressure crystallizer <NUM> is flashed into a low-pressure crystallizer <NUM>. Low pressure steam <NUM> from the low-pressure crystallizer <NUM> flows through a steam scrubber (not shown) and then either to a low-pressure turbine or to the low-pressure side of a dual entry turbine <NUM>. The brine slurry mixture is flashed to atmospheric pressure in an atmospheric flash tank <NUM> and then flows into the clarifiers.

A primary clarifier <NUM> comprising an internally recirculating reactor type clarifier precipitates silica down to close to equilibrium values for the various scaling constituents at the operating temperature of the brine, e.g., approximately <NUM>°F. Primary Clarifier Overflow ("PCO") refers to the clarified brine flowing out of the primary clarifier <NUM>, and Primary Clarifier Underflow ("PCU") refers to the slurry flowing out of the bottom of the primary clarifier <NUM>. The precipitated solids are flocculated and settled to the bottom of the primary clarifier tank <NUM>. A relatively clear brine PCO passes from the primary clarifier <NUM> to a secondary clarifier <NUM> that removes additional suspended solids from the brine. Secondary Clarifier Overflow ("SCO") <NUM> refers to the clarified brine flowing out of the secondary clarifier <NUM>, and Secondary Clarifier Underflow ("SCU") refers to the slurry flowing out of the bottom of the secondary clarifier <NUM>.

Flocculent and scale inhibitor are added between the primary clarifier <NUM> and the secondary clarifier <NUM> to enhance solids settling and to prevent the precipitation of radioactive alkaline earth salts. The stable SCO <NUM> from the secondary clarifier <NUM> is pumped into injection wells <NUM>. A portion of the precipitated solids from the PCU and the SCU is recycled upstream to the standard-pressure crystallizer <NUM> as seed material <NUM>. Accumulated solids in both the primary clarifier <NUM> and the secondary clarifier <NUM> are routed to a horizontal belt filter ("HBF") <NUM> for solids removal.

The HBF <NUM> separates liquid from the solids in the slurry from the PCU and the SCU. The liquid can be separated from the solids by vacuum and passes through a filter cloth that rests on top of the carrier belt. The first stage of the HBF is a pH <NUM> acid wash of the slurry with hydrochloric acid to remove any lead precipitates from the filter cake. The second stage is a pH <NUM> condensate water wash to neutralize any residual acid in the filter cake. The third stage of the HBF steam dries the filter cake. The filter cake is transported to a local landfill for disposal.

The silica and iron concentrations in the brine at the PCO, SCO and injection wells of the power plant operations are summarized as follows in Table <NUM>:.

The polished brine <NUM> that exits the SCO from the power plant <NUM> with reduced amounts of scaling constituents is well suited for mineral extraction, and rather than injecting the polished brine <NUM> into the injection well <NUM>, it is made available to the system and process <NUM> and/or to the CCAD process <NUM> for selective recovery of lithium and/or other minerals from the polished brine <NUM>.

As illustrated in <FIG>, a feed brine, such as a geothermal brine or the brine <NUM> that exits the SCO from the power plant <NUM> having reduced amounts of scaling constituents passes to the system and process <NUM> for mineral and/or lithium extraction. The feed brine is passed into the impurity removal circuit <NUM> having a first set of reaction tanks <NUM> and a first clarifier <NUM> to remove iron and silica followed by a second set of reaction tanks <NUM> and a second clarifier <NUM> to remove manganese and zinc primarily. A first or iron/silica precipitation stage 300A of the impurity removal circuit <NUM> includes adding limestone 310A and injecting air 310B into brine. The air causes the dissolved iron to oxidize and the pH to drop. A low pH solution reduces the rate of reaction; therefore, limestone is used to neutralize this effect and maintain the pH around <NUM>. The first clarifier <NUM> is positioned downstream of the first set of reaction tanks <NUM> to settle out the silica and iron in the brine. The precipitated solids are settled to the bottom of the first clarifier tank <NUM>. The first stage 300A of the impurity removal circuit <NUM> reduces the iron concentration in the brine overflow from about <NUM>,<NUM> part per million (ppm) down to less than about <NUM> ppm and reduces the silica concentration in the brine overflow from about <NUM> ppm down to less than about <NUM> ppm. A relatively clear brine overflow passes from the first clarifier <NUM> to a second or zinc/manganese precipitation stage 300B of impurity removal circuit <NUM>.

The second stage 300B of the impurity removal circuit <NUM> includes adding limestone 312A and/or lime 312B to the brine in the second set of reaction tanks <NUM>. This causes the brine pH to elevate to around <NUM>. The second clarifier <NUM> is positioned downstream of the second set of reaction tanks <NUM> and allows the metals as oxides and/or hydroxides (primarily zinc and manganese) to settle. During the second stage 300B of the impurity removal circuit <NUM>, the manganese concentration in the brine is reduced from about <NUM> ppm down to less than about <NUM> ppm, while zinc concentration is reduced about <NUM> ppm down to less than <NUM> ppm in the second stage 300B of the impurity removal circuit <NUM>. Accumulated solids in the first clarifier <NUM> and the second clarifier <NUM> are respectively routed to a pneumapress filter HBF to prepare an Fe/Si filter cake <NUM> and a Mn/Zn filter cake <NUM>.

Acid is then added <NUM> to the brine from the second clarifier <NUM> to reduce the pH back down to between about <NUM> and about <NUM>, with a brine temperature between about <NUM> and about <NUM>, which is suitable for the CCAD circuit <NUM>. The dissolved solids in the polished brine at this point in the process comprise primarily salts (as chlorides) with high concentrations of sodium, potassium, and calcium. The lithium concentration is comparatively low at only ±<NUM> ppm.

The polished brine (stream <NUM> in <FIG>) can then passed to the CCAD circuit <NUM>, which concentrates the lithium in the polished brine by approximately <NUM> times and simultaneously separates the lithium from the other salts (calcium is of particular concern for downstream operations). The target result is an enhanced lithium chloride product stream <NUM> in <FIG> and <FIG> (stream <NUM> in <FIG>) (stream <NUM> or stream <NUM> in <FIG>) (with some residual impurities) of around approximately <NUM>,<NUM> to <NUM>,<NUM> ppm lithium. The residual brine can be returned for reinjection through injection wells <NUM>.

If the inventive CCAD system is used with salar, continental or other non-geothermal brines, the brine feedstock can be passed directly to the CCAD circuit <NUM> with minimal pretreatment such as granular media filtration (GMF) and, if necessary, residual organic removal. Salar or continental brines with low iron and silica content may require only minimal pretreatment before being passed to the CCAD circuit <NUM> for concentrating lithium when compared to brines from the Salton Sea Known Geothermal Resource Area (SSKGRA). The pretreatment process may include dilution with water to prevent solids precipitating from brines that are close to saturation. In addition, GMF can be used to reduce total suspended solids (TSS) to below <NUM> ppm before introducing the brine solution. Oil field brines may require pretreatment processing to remove any residual organic material before being passed to the CCAD circuit <NUM>. The bulk of the organic material can be removed by a device such as an API oil-water separator. Any remaining organic materials can be removed with a mixed bed GMF that includes activated carbon as part of the mixed bed.

Referring now to <FIG>, the CCAD circuit <NUM> includes a series of sequential steps in a cyclic process. The CCAD circuit <NUM> has a plurality of adsorption beds or columns <NUM> each containing a lithium selective adsorbent. The adsorption beds <NUM> are sequentially subjected to individual process zones (A, B, C, D) as part of the CCAD circuit <NUM>. Each of the process zones A, B, C, and D includes one or more of the adsorbent beds <NUM> configured in parallel, in series, or in combinations of parallel and series, flowing either in up flow or down flow modes. The process zones of the CCAD circuit <NUM> include an adsorption displacement zone A, an adsorption loading zone B, an entrainment rejection (ER) zone C, and an elution zone D. Brine fluid flow through the CCAD circuit <NUM> is controlled by pumping flow rates and/or predetermined indexing of a central multi-port valve system or of the adsorbent beds <NUM>, creating a process where the adsorption beds <NUM> continually cycle through the individual process zones A, B, C and D.

In order to eliminate the possibility of residual feedstock brine <NUM> and brine salts from entering the elution zone D, an elution volume of feed brine <NUM> is displaced from the adsorbent bed(s) <NUM> of the brine displacement zone A using a portion of high lithium concentration product eluate <NUM> from the elution zone D. The elution volume of displacement feed brine <NUM> drawn from the elution zone D into the brine displacement zone A is at least enough to displace one adsorbent bed void fraction during an index time (the time interval between rotary valve indexes).

The feedstock brine <NUM>, which can be the polished geothermal brine (stream <NUM> in <FIG>) or a salar, continental or other non-geothermal feedstock brine, is pumped to the adsorbent bed(s) <NUM> in the loading zone B with a predetermined elution time sufficient to completely or almost completely exhaust the lithium selective adsorbent, and the depleted brine exiting the loading zone B is sent to raffinate <NUM>. The loading zone B is sized such that under steady state operation of the CCAD circuit <NUM>, the complete lithium adsorption mass transfer zone is captured within the zone B. The steady state operation treats the feedstock brine <NUM> so that the maximum lithium loading is achieved without significant lithium leaving with the lithium depleted raffinate <NUM> as tails.

Next, a portion of raffinate 414A is pumped to the entrainment rejection (ER) zone C to displace latent eluate solution <NUM>, which is carried forward as entrained fluid within the column transitioning from the loading zone C into the elution zone D in the cyclic process, back to the inlet of the elution zone D. The elution volume of the displacement fluid 414A drawn from the raffinate <NUM> to displace latent eluate solution <NUM> back into the ER zone C is at least enough to displace one adsorbent bed void fraction during the rotary valve index time.

Then, an eluant (stripping solution) <NUM> is pumped countercurrent to the adsorbent advance (fluid flow is illustrated as right to left, while the adsorbent beds movement is illustrated as left to right) into the elution zone D to produce an enhanced lithium product stream <NUM>. Eluant <NUM> comprises a low concentration lithium product eluant (as neutral salts, generally lithium chloride) in water at a concentration from about <NUM>/kg to about <NUM>/kg lithium and at temperatures of about <NUM> to about <NUM>. Properly tuned, the enhanced lithium product stream <NUM> will have a lithium concentration <NUM>- to <NUM>-fold that of the eluant <NUM> and greater than <NUM>% rejection of brine hardness ions and most other brine components. The portion of high lithium concentration product eluate <NUM> that is recycled and displaces the displacement feed brine <NUM> from the displacement zone A is enough fluid to completely displace brine salts from the adsorbent before the adsorbent enters the elution zone D. This means that the displacement feed brine <NUM> may be recycled introduced to the loading zone B with the feedstock brine <NUM>. Depending on the tuning parameters of the CCAD circuit <NUM>, the low lithium concentration in the recycled displacement feed brine <NUM> could significantly increase the effective concentration of lithium entering the loading zone B. This enhanced feed concentration results in significantly increased lithium capacity and greater lithium recovery efficiency, especially in the case of feedstock brines with low lithium concentrations (under <NUM>/kg).

An optional membrane separation <NUM> can be inserted into stream <NUM>, which includes but is not limited to, reverse osmosis or nano-filtration, to dewater and concentrate the lithium product solution <NUM> producing a product eluate with higher lithium concentration <NUM>, while producing a recycle stream <NUM> suitable for use as make-up for fresh eluant <NUM>. The optional membrane dewatering of the enhanced lithium product stream <NUM> would recycle a portion of the water <NUM> used in the preparation of the eluant solution <NUM>. Depending on the permeability of the membrane, a portion of the lithium could pass through the membrane without passing multivalent brine components and become the lithium make-up for fresh eluant <NUM>.

The CCAD circuit <NUM> recovers between about <NUM>% and about <NUM>% of the lithium from the feed brine and produces the enhanced lithium chloride product stream <NUM> in <FIG> and <FIG> (stream <NUM> in <FIG>) (stream <NUM> or stream <NUM> in <FIG>) having a concentration <NUM>- to <NUM>-fold that of the feed brine (e.g., polished brine stream <NUM> in <FIG> or other natural or synthetic brine feedstock) with a greater than <NUM>% rejection of brine hardness ions. The production of this high purity lithium, directly from brine, without the need for extra rinse water, is an extremely cost-effective process of obtaining commercially valuable and substantially pure lithium chloride, suitable for conversion to battery grade carbonate or hydroxide.

The lithium selective adsorbent in the adsorbent beds <NUM> can be lithium alumina intercalates prepared from hydrated alumina, lithium aluminum layered double hydroxide chloride (LDH), LDH modified activated alumina, LDH imbibed ion exchange resins or copolymers or molecular sieves or zeolites, layered aluminate polymer blends, lithium manganese oxides (LMO), titanium oxides, immobilized crown ethers, or other lithium ion selective binding material.

The process for selective adsorption and recovery of lithium from natural and synthetic brines disclosed herein is further illustrated by the following examples, which are provided for the purpose of demonstration rather than limitation.

An exemplary CCAD circuit <NUM> was configured in general accordance with <FIG> using thirty (<NUM>) individual adsorption columns <NUM> arranged in a rotating carrousel pilot skid with a central rotary valve design with each column having a <NUM> inch inner diameter and <NUM> inches in length, each packed with <NUM> of macroporous resin imbibed with lithium alumina intercalate. All metal analysis was performed using inductively coupled plasma (ICP) analysis. The adsorbent bed advance rate was set to <NUM> minutes per forward step of the rotating carrousel. The turret of adsorption columns was maintained in an enclosure at <NUM>-<NUM>. All feed solutions were introduced to the circuit at <NUM>. The brine displacement zone (zone A) comprised four (<NUM>) columns in series and the flow rate was set at <NUM>/min. The adsorption zone (zone B) comprised six (<NUM>) sets of three (<NUM>) parallel columns arranged in series. The feed brine comprised a treated Salton Sea geothermal brine at pH <NUM> where the silica, iron, manganese, and zinc had been selectively removed in a pretreatment protocol and the brine flow rate was set at <NUM>/min, specific gravity <NUM>. Next the ER zone (zone C) comprised two (<NUM>) columns in series and the lithium depleted brine raffinate entered the ER zone at a flow rate of <NUM>/min. The elution zone (zone D) comprised three (<NUM>) pairs of parallel columns arranged in series and was fed by <NUM>/min of low concentration lithium (<NUM>/L) in water as eluate. The product lithium was taken from the last of the three (<NUM>) pairs of parallel columns at a flow rate of <NUM>/min and the remainder of the flow entered zone A to displace brine to the brine feed port at the flow rate of <NUM>/min (as stated above).

The CCAD circuit <NUM>, after achieving steady state operation, provided excellent results for lithium recovery. The feed brine had an average lithium concentration of <NUM>/L while the lithium product stream had an average lithium concentration of <NUM>,<NUM>/L, and as such, in this example, greater than <NUM>% of the lithium from the feed brine was recovered.

In addition, the inventive process provides excellent results for the preparation of a lithium chloride product having low calcium and magnesium concentrations, which is particularly suited as a feedstock for a solvent extraction and electrowinning (SX/EW) process, a solvent extraction and membrane electrolysis (SX/EL) process, or other recovery technology process for production of high purity lithium hydroxide and lithium carbonate for battery production. The feed brine contained <NUM>,<NUM>/L of calcium yet the lithium product stream contained only <NUM>/L of calcium, representing a <NUM>% rejection of calcium from the feed brine to the lithium product stream.

Another exemplary CCAD circuit <NUM> was configured in general accordance with <FIG> using thirty (<NUM>) individual adsorption columns arranged in a rotating carrousel pilot skid with a central rotary valve design with each column having a <NUM> inch inner diameter and <NUM> inches in length, each packed with <NUM> of macroporous resin imbibed with lithium alumina intercalate. All metal analysis was performed using ICP analysis. The adsorbent bed advance rate was set to <NUM> minutes per forward step of the rotating carrousel. The turret of columns was maintained in an enclosure at about <NUM>. All feed solutions were introduced to the system at <NUM>. The brine displacement zone A comprised four (<NUM>) columns in series and the flow rate was set at <NUM>/min. The adsorption zone B comprised six (<NUM>) sets of three (<NUM>) parallel columns arranged in series. The feed brine comprised treated Salton Sea geothermal brine at pH <NUM> where the silica, iron, manganese, and zinc had been removed in a pretreatment protocol and the brine flow rate was set at <NUM>,<NUM>/min, specific gravity <NUM>. Next the ER zone C comprised two (<NUM>) columns in series and the lithium depleted brine raffinate entered the ER zone C at a flow rate of <NUM>/min. The elution zone D comprised three (<NUM>) pairs of parallel columns arranged in series and was fed by <NUM>/min of low concentration lithium (<NUM>/kg) in water as eluate. The product lithium was taken from the last of the three (<NUM>) pairs of parallel columns at a flow rate of <NUM>/min and the remainder of the flow entered the zone A to displace brine to the brine feed port at the flow rate of <NUM>/min.

In this example, the CCAD circuit <NUM>, after achieving steady state operation, provided excellent results for lithium recovery. The feed brine had an average lithium concentration of <NUM>/kg while the lithium product stream had an average lithium concentration of <NUM>,<NUM>/kg, and the average concentration of lithium in the raffinate was <NUM>/kg, as such, in this example, lithium recovery was greater than <NUM>% of the lithium from the feed brine. Table <NUM> below shows the steady state performance of the inventive process as exemplified in this example. The CCAD product stream was <NUM>% of the volume of the treated Salton Sea Brine feed stream. Quantities of metals are expressed in mg/kg and are corrected for differences in specific gravity of feed brine vs CCAD product.

In addition, similar to the first example and as illustrated in <FIG>, the inventive CCAD circuit <NUM> provides excellent results for the preparation of a lithium chloride product having low calcium and magnesium concentrations, which is particularly suited as a feedstock for a SX/EW process, a SX/EL process, or other recovery technology process for production of high purity lithium hydroxide and lithium carbonate for battery production. The feed brine contained <NUM>,<NUM>/kg of calcium yet the lithium product stream contained only <NUM>/kg of calcium, representing a <NUM>% rejection of calcium from the feed brine to the lithium product stream. Magnesium rejection was similar to calcium rejection giving indication that the inventive process could be well suited to salar, continental, petro-, or other non-geothermal feedstock brines.

The CCAD circuit <NUM> having only one multi-port valve is far simpler to operate than classical continuous fixed bed systems having <NUM>-<NUM> valves. In addition to the high lithium yields, the CCAD circuit <NUM> also uses absorbent, water, and reagents more efficiently than fixed bed systems. In the above examples, the CCAD circuit <NUM> requires only about half the volume absorbent as a comparable classical fixed bed system.

Turn back now to <FIG>, after leaving the CCAD circuit <NUM>, the enhanced lithium chloride product stream <NUM> (stream <NUM> in <FIG>) (stream <NUM> or stream <NUM> in <FIG>) is passed to the lithium chloride conversion circuit <NUM> where the lithium concentration is further increased to in excess of about <NUM>,<NUM> ppm. The lithium chloride conversion circuit <NUM> removes selected remaining impurities and further concentrates lithium in the lithium chloride product stream <NUM> before crystallization or electrolysis.

The lithium chloride conversion circuit <NUM> initially removes any remaining impurities <NUM>, namely calcium, magnesium and boron, from the lithium chloride product stream <NUM>. First, sodium hydroxide (caustic soda) is added in order to precipitate calcium and magnesium oxides from the lithium chloride product stream <NUM>. The precipitated solids can produce a Ca/Mg filter cake <NUM>. Boron is then removed by passing the lithium chloride product stream <NUM> through a boron ion exchange (IX) circuit <NUM>. The boron IX circuit is filled with an adsorbent that preferentially attracts boron, and divalent ions (essentially calcium and magnesium) are further removed in a divalent ion exchange (IX) circuit <NUM>. This "polishing" step <NUM> ensures that these calcium, magnesium and boron contaminants do not end up in the lithium carbonate or lithium hydroxide crystals.

Then, the lithium chloride conversion circuit <NUM> uses a reverse osmosis membrane step <NUM> to initially concentrate lithium in the lithium product stream <NUM> (target estimate from approximately <NUM>,<NUM> ppm to <NUM>,<NUM> ppm). A triple effect evaporator <NUM> is then used to drive off water content and further concentrate the lithium product stream. The triple effect evaporator <NUM> utilizes steam <NUM> from geothermal operations and/or fuel boiler to operate. After processing through the evaporator <NUM>, lithium concentration in the product stream is increased from about <NUM>,<NUM> ppm to about <NUM>,<NUM> ppm.

The next steps in the lithium chloride conversion circuit <NUM> convert the lithium chloride in solution to a lithium carbonate crystal. Sodium carbonate is added <NUM> to the lithium chloride product stream <NUM> to precipitate lithium carbonate <NUM>. The lithium carbonate <NUM> slurry is sent to a centrifuge <NUM> to remove any excess moisture resulting in lithium carbonate cake. The lithium carbonate cake is re-dissolved <NUM>, passed through a final purification or impurity removal step <NUM>, and recrystallized <NUM> with the addition of carbon dioxide <NUM>. The crystallized lithium carbonate product is then suitable for packaging <NUM>.

<FIG> illustrates another exemplary embodiment of the system and process <NUM> for recovery of lithium. After leaving the CCAD circuit <NUM>, rather than using evaporation <NUM> exemplified in <FIG>, a solvent extraction process <NUM> concentrates lithium in the enhanced lithium chloride product stream <NUM> in <FIG> and <FIG> (stream <NUM> in <FIG>) (stream <NUM> or stream <NUM> in <FIG>) using liquid-liquid separation, and after solvent extraction <NUM> and electrolysis <NUM>, the lithium is subsequently crystallized <NUM> into lithium hydroxide product <NUM>.

Similar to the embodiment illustrated in <FIG>, the lithium chloride conversion circuit <NUM> first precipitates calcium and magnesium <NUM> through the addition sodium hydroxide (caustic soda) resulting with a Ca/Mg filter cake is produced <NUM>. The pH of the lithium chloride product stream <NUM> is lowered to about <NUM> in step <NUM> and then the acidified lithium chloride product stream <NUM> is introduced to the solvent extraction step <NUM> in pulsed columns (tall vertical reaction vessels). The flow is scrubbed <NUM> and then stripped <NUM> with sulfuric acid producing a lithium sulfate product. The lithium sulfate product goes through an electrolysis unit <NUM> producing lithium hydroxide crystals <NUM>. The lithium hydroxide crystals are then dried and packaged <NUM>.

Turning now to <FIG> illustrating yet another exemplary embodiment of the process for recovery of lithium, the feed source is an incoming brine (e.g., a geothermal brine or the polished brine <NUM>) (stream <NUM>) and dilution water (stream <NUM>). The incoming dilution water (stream <NUM>) is mixed with filtrate (stream <NUM>) from a Fe/Si precipitate filter <NUM>, then split, part (stream <NUM>) being used as wash to the Fe/Si precipitate filter <NUM> and the balance (stream <NUM>) being added to the incoming brine (stream <NUM>). The combined brine, dilution water and Fe/Si filtrate (stream <NUM>) is pumped (stream <NUM>) to the Fe/Si precipitation stage 300A of the impurity removal circuit <NUM>. Limestone 310A (stream <NUM>) is slurried with recycled barren brine (stream <NUM>). The limestone/recycled barren brine slurry is added (stream <NUM>) to the first set of reaction tanks <NUM> along with recycled precipitate seed (stream <NUM>). Air is injected (stream <NUM>/<NUM>) into the first tank <NUM> using a blower <NUM>. The iron is oxidized, and iron and silica are precipitated according to the following stoichiometry:.

2CaCO<NUM> + 2Fe<NUM>+ + <NUM><NUM>O + ½O<NUM> → 2Fe(OH)<NUM> + 2CO<NUM> + 2Ca<NUM>+.

3CaCO<NUM> + <NUM><NUM>SiO<NUM> + 2Fe(OH)<NUM> → Ca<NUM>Fe<NUM>Si<NUM>O<NUM> + 3CO<NUM> + <NUM><NUM>O.

The spent air is vented (stream <NUM>) from the first tanks <NUM>, and the exit slurry (stream <NUM>) is pumped (stream <NUM>) to a thickener or clarifier <NUM> where flocculent (stream <NUM>/<NUM>) is added and the solids are settled out. The underflow from the clarifier <NUM> (stream <NUM>) is pumped (stream <NUM>) back to the first set of reaction tanks <NUM> as seed (stream <NUM>) and (stream <NUM>) to the filter feed tank <NUM>. Precipitate from the Ca/Mg precipitation stage <NUM> of the impurity removal circuit <NUM> is added (stream <NUM>) and the combined slurry (stream <NUM>) is filtered in the Fe/Si filter <NUM>. The resulting Fe/Si filter cake is washed with dilution water (stream <NUM>) and the washed filter cake <NUM> (stream <NUM>) leaves the circuit <NUM>. The filtrate (stream <NUM>) is pump (stream <NUM>) to the dilution water tank <NUM>.

The clarifier overflow (stream <NUM>) from the Fe/Si precipitation stage 300A is combined with filtrate from a Zn/Mn precipitate filter <NUM> (stream <NUM>) in a feed tank <NUM> and the combined solution (stream <NUM>) is pumped (stream <NUM>) to the Zn/Mn precipitation stage 300B. Recycled precipitate (stream <NUM>) is added as seed and lime 312B (stream <NUM>) is slaked with recycled barren solution (stream <NUM>). Any gas released is vented (stream <NUM>). The lime/recycled barren solution is added (stream <NUM>) to the second set of reaction tanks <NUM> to raise the pH to just over <NUM> and precipitate zinc, manganese and lead oxides/hydroxides.

Any gas released is vented (stream <NUM>) from the second set of reaction tanks <NUM>. The exit slurry (stream <NUM>) is pumped (stream <NUM>) to the clarifier <NUM>. Recycled solids from a subsequent polishing filter <NUM> (stream <NUM>) and flocculent (stream <NUM>/<NUM>) are added and the precipitated hydroxides are settled out. The clarifier underflow (stream <NUM>) is pumped (stream <NUM>) to seed recycle (stream <NUM>) and to the Zn/Mn precipitate filter <NUM> (stream <NUM>). The resulting Zn/Mn filter cake is washed with process water (stream <NUM>) and the washed filter cake <NUM> (stream <NUM>) leaves the circuit <NUM>. The filtrate (stream <NUM>) is pumped (stream <NUM>) to the feed tank <NUM> ahead of the Zn/Mn precipitation stage 300B. The clarifier overflow (stream <NUM>) is mixed with mother liquor (stream <NUM>) from a first precipitation of lithium carbonate <NUM> and the combined solution (stream <NUM>) is pumped (stream <NUM>) through the polishing filter <NUM> to capture residual solids. The captured solids are backwashed out (stream <NUM>) and sent to the Zn/Mn precipitate clarifier <NUM>.

The filtrate from the polishing filter <NUM> (stream <NUM>) is mixed with spent eluant from the divalent IX circuit (stream <NUM>) and hydrochloric acid <NUM> (stream <NUM>/<NUM>) is added to reduce the pH to approximately <NUM>. The resulting solution is cooled to approximately <NUM>°F in the mixing tank <NUM> and the cooled solution (stream <NUM>) is passed through the CCAD circuit <NUM> in which the lithium chloride is selectively captured onto the lithium selective adsorbent. The resulting barren solution (stream <NUM>) is pumped (stream <NUM>) to a holding tank <NUM> from which it is distributed as follows:.

The loaded adsorbent is eluted with process water (stream <NUM>) and the resulting eluate (stream <NUM>) is pumped (stream <NUM>) to a third set of reaction tanks <NUM> for addition impurity removal <NUM>, initially calcium and magnesium precipitation. Sodium hydroxide <NUM> (stream <NUM>) is dissolved in process water (stream <NUM>) and added (stream <NUM>) to the tanks <NUM>. Sodium carbonate <NUM> (stream <NUM>) is dissolved in process water (stream (<NUM>) pumped from a process water reservoir <NUM> and added (stream <NUM>). A bleed of mother liquor (stream <NUM>) from a second precipitation of lithium carbonate <NUM> and the spent regenerant from the boron IX circuit <NUM> (stream <NUM>) are also treated in the Ca/Mg precipitation section of the lithium chloride conversion circuit <NUM>. The alkali earth ions (mainly Ca<NUM>+ and Mg<NUM>+) are precipitated according to the following stoichiometry:.

Ca<NUM>+ + Na<NUM>CO<NUM> → 2Na+ + Ca(CO)<NUM>.

Any vapor evolved is vented (stream <NUM>). The exit slurry (stream <NUM>) is pumped (stream <NUM>) to a thickener or clarifier <NUM>, flocculent is added (stream <NUM>/<NUM>) and the precipitate is settled out. The overflow (stream <NUM>) is pumped (stream <NUM>) through a polishing filter <NUM>. The underflow (stream <NUM>) is pumped (stream <NUM>) to a mixing tank <NUM> where it joins the solids (stream <NUM>) from the polishing filter <NUM> and the combined slurry (stream <NUM>) is pumped (stream <NUM>) back to the feed tank <NUM> ahead of the Fe/Si filter <NUM>. The filtrate (stream <NUM>) from the polishing filter <NUM> is pumped (stream <NUM>) to a feed tank <NUM> ahead of the boron IX circuit <NUM>.

The filtrate (stream <NUM>) from the Ca/Mg precipitation section of the lithium chloride conversion circuit <NUM> is pumped (stream <NUM>) through the boron IX circuit <NUM> in which boron is extracted onto an ion exchange resin. The loaded resin is stripped with dilute hydrochloric acid (stream <NUM>) that is made from concentrated hydrochloric acid (stream <NUM>), process water (stream <NUM>) and recycled eluate (stream <NUM>). The first <NUM>% of the spent acid (stream <NUM>), assumed to contain <NUM>% of the boron eluted from the loaded resin, is mixed with similar spent acid from the subsequent divalent IX circuit <NUM> and recycled to the feed to the CCAD circuit <NUM> (stream <NUM>). The balance of the spent acid (stream <NUM>) is recycled to the eluant make-up tank and recycled (stream <NUM>). The stripped resin is regenerated with dilute sodium hydroxide (stream <NUM>) that is made from fresh sodium hydroxide (stream <NUM>), process water (stream <NUM>) and recycled regenerant (stream <NUM>). The first <NUM>% of the spent regenerant (stream <NUM>) is recycled to the Ca/Mg precipitation section and the balance (stream <NUM>) returns to a regenerant make-up tank <NUM> and is recycled (stream <NUM>).

The boron-free product solution (stream <NUM>) is pumped (stream <NUM>) through divalent IX circuit <NUM> in which <NUM> percent of any remaining divalent ions (essentially only Ca<NUM>+ and Mg<NUM>+) are captured by the resin. The loaded resin is stripped with dilute hydrochloric acid (stream <NUM>) that is made from fresh hydrochloric acid (stream <NUM>), process water (stream <NUM>) and recycled spent acid (stream <NUM>). The first <NUM>% of the spent acid (stream <NUM>) joins the first half of the spent acid from the boron IX circuit <NUM> and the combined solution (stream <NUM>) is sent back to the feed tank <NUM> ahead of the CCAD circuit <NUM>. The balance of the spent acid (stream <NUM>) goes back to an eluant make-up tank <NUM> and is recycled (stream <NUM>). The stripped resin is converted back to the sodium form by regeneration with dilute sodium hydroxide (stream <NUM>). The first <NUM>% of the spent regenerant (stream <NUM>), assumed to have regenerated <NUM>% of the resin, joins the spent regenerant (stream <NUM>) from the boron ion exchange stage and goes back (stream <NUM>) to the Ca/Mg precipitation section. The balance of the spent regenerant (stream <NUM>) returns to the regenerant make-up tank <NUM>.

The purified solution (stream <NUM>) is pumped (stream <NUM>) to a feed tank <NUM> ahead of reverse osmosis <NUM> and mixed with wash centrate (stream <NUM>) from a first lithium carbonate centrifuge <NUM>. The combined solution is split, part (stream <NUM>) being used to dissolve sodium carbonate and the balance (stream <NUM>) being pumped (stream <NUM>) through a reverse osmosis stage in which the water removal is manipulated to give <NUM> percent saturation of lithium carbonate in the concentrate (stream <NUM>). The permeate goes to the process water reservoir (stream <NUM>).

The partially concentrated solution from reverse osmosis <NUM> is further concentrated in a triple-effect evaporation <NUM>. The solution ex reverse osmosis (stream <NUM>) is partly evaporated by heat exchanger <NUM> with incoming steam (stream <NUM>). The steam condensate (stream <NUM>) goes to the process water reservoir <NUM>, and the steam/liquid mixture to the heat exchanger <NUM> (stream <NUM>) is separated in a knock-out vessel <NUM>. The liquid phase (stream <NUM>) passes through a pressure reduction <NUM> (stream <NUM>) and is further evaporated in a heat exchanger <NUM> with steam (stream <NUM>) from the first knock-out vessel <NUM>. The condensate (stream <NUM>) is pumped (stream <NUM>) to the process water reservoir <NUM>. The steam-liquid (stream <NUM>) mixture is separated in a second knock-out vessel <NUM>. The liquid (stream <NUM>) goes through another pressure reduction step <NUM> (stream <NUM>) and is evaporated further another heat exchanger <NUM> with steam (stream <NUM>) from the second knock-out vessel <NUM>. The condensate (stream <NUM>) is pumped (stream <NUM>) to the process water reservoir <NUM>. The steam-liquid mixture (stream <NUM>) is separated in a third knock-out vessel <NUM>. The steam (stream <NUM>) is condensed (stream <NUM>) by heat exchanger <NUM> with cooling water and pumped (stream <NUM>) to the process water reservoir <NUM>.

The concentrated solution (stream <NUM>) is pumped (stream <NUM>) to the lithium carbonate crystallization section <NUM>. Sodium carbonate <NUM> (stream <NUM>) is dissolved in dilute lithium solution (stream <NUM>) from the feed tank <NUM> ahead of reverse osmosis <NUM> and added (stream <NUM>/<NUM>) to precipitate lithium carbonate. Any vapor evolved is vented (stream <NUM>). The resulting slurry (stream <NUM>) is pumped (stream <NUM>) to a centrifuge in which the solution is removed, leaving a high solids cake. A small amount (stream <NUM>) of process water is used to wash the solids. The wash centrate (stream <NUM>) is returned to the feed tank ahead of reverse osmosis <NUM>. The primary centrate (stream <NUM>) is recycled to a feed tank <NUM> ahead of the polishing filter <NUM> before the CCAD circuit <NUM>.

The washed solids (stream <NUM>) from the first centrifuge <NUM> are mixed with wash (stream <NUM>) and primary centrate (stream <NUM>) from a second centrifuge <NUM>. The resulting slurry (stream <NUM>) is pumped to <NUM> bar abs. (stream <NUM>) and contacted with pressurized carbon dioxide <NUM> (stream <NUM>) to completely dissolve the lithium carbonate according to the following stoichiometry:.

Li<NUM>CO<NUM> + CO<NUM> + H<NUM>O → 2Li+ + 2HCO<NUM>-.

The amount of primary centrate is manipulated to give <NUM> percent saturation of lithium carbonate in the solution (stream <NUM>) leaving the redissolution step <NUM>. Any other species (Ca, Mg) remain as undissolved carbonates. The temperature of this step is held at <NUM>°F by heat exchange with chilled water <NUM> (stream <NUM> in, stream <NUM> out). The resulting solution of lithium bicarbonate (stream <NUM>) is filtered <NUM> and the solid impurities leave the circuit <NUM> (stream <NUM>). The filtrate (stream <NUM>) is heated by live steam (stream <NUM>) injection, to decompose the dissolved lithium bicarbonate to solid lithium carbonate and gaseous carbon dioxide:.

2Li+ + 2HCO<NUM>- → Li<NUM>CO<NUM>↓ + CO<NUM>↑ + H<NUM>O.

The carbon dioxide formed (stream <NUM>) is cooled by chiller <NUM> (stream <NUM>) and mixed with surplus carbon dioxide (stream <NUM>) from the re-dissolution step <NUM> and make-up carbon dioxide <NUM> (stream <NUM>) in a knock-out vessel <NUM> from which the condensed water (stream <NUM>) is removed and the carbon dioxide (stream <NUM>) is compressed <NUM> and returned (stream <NUM>) to the lithium re-dissolution step <NUM>. The slurry of purified lithium carbonate (stream <NUM>) is pumped (stream <NUM>) to the second centrifuge <NUM> in which it is separated and washed with process water (stream <NUM>). The wash centrate (stream <NUM>) is returned to the re-dissolution step <NUM>. The primary centrate (stream <NUM>) is pumped (stream <NUM>) back to the Ca/Mg precipitation section (stream <NUM>) and to the lithium re-dissolution step (stream <NUM>). The washed solids (stream <NUM>) leave the circuit as the lithium carbonate product.

The condensate from the carbon dioxide knock-out vessel <NUM> (stream <NUM>) and condensate from the carbon dioxide compressor <NUM> (stream <NUM>) are combined and sent (stream <NUM>) to the process water reservoir <NUM>. The permeate from the reverse osmosis <NUM> (stream <NUM>) and the condensates from the evaporation sequence <NUM> (streams <NUM>, <NUM>, <NUM>) also go to the process water reservoir <NUM>. Make-up water (stream <NUM>) is added to the process water reservoir <NUM>, if necessary, to balance the following requirements for process water:.

<FIG> shows an illustrative example of mineral recovery as part of the system and process <NUM> disclosed herein. After the impurity removal circuit <NUM>, the recovery of metals from the second filter cake <NUM> is possible through a solvent extraction (SX) circuit <NUM>. The SX circuit leaches manganese and zinc from the filter cake with an application of an acid and then selectively strips the manganese and zinc using a solvent under different pH conditions. The resulting intermediate products are zinc sulfate liquor and manganese sulfate liquor, both of which can be sold as agricultural products, processed further by electrowinning into metallic form, or as feedstock to alternative products such as electrolytic manganese dioxide among others.

The SX circuit <NUM> begins with leaching <NUM> the second filter cake <NUM> in a stirred, repulp reactor <NUM> with sulfuric acid (H<NUM>SO<NUM>) or hydrochloric acid (HCl) to reduce the pH down to about <NUM> (<NUM>). A reducing agent such as NaHS or SO<NUM> is added to the reactor <NUM> to ensure all of the manganese is in the +<NUM>-valence state for leaching. This improves the kinetics and yield of the acid leach. The discharge from the leach reactor <NUM> will have its pH raised to approximately <NUM> - <NUM> with lime to precipitate any residual iron. The slurry will then be pumped to a polishing filter (not shown) followed by a pH adjustment to approximately <NUM> to approximately <NUM>. This becomes the Zn/Mn aqueous feed solution <NUM> to the SX circuit <NUM>.

The SX circuit <NUM> includes a zinc extraction stage <NUM>, a zinc scrubbing stage <NUM>, and a zinc stripping stage <NUM>. The Zn/Mn aqueous feed solution <NUM> and an organic solvent <NUM> (e.g., Cytex <NUM>) are fed in a counter-current manner into a first stage contactor in which the two phases are mixed and Zn is transferred from the aqueous phase into the organic phase. After settling, the aqueous raffinate is separated <NUM> and pH adjusted to between approximately <NUM> and approximately <NUM>. After pH adjustment <NUM>, the raffinate containing Mn <NUM> is sent for recovery of a manganese sulfate product liquor <NUM>.

From the zinc extraction stage <NUM>, the zinc loaded solvent <NUM> is fed into a second stage contactor where it is scrubbed with a suitable aqueous solution <NUM> to remove small amounts of impurities remaining. After settling in the zinc scrubbing stage <NUM>, the scrub raffinate will be recycled to an appropriate stream <NUM>. The loaded solvent <NUM> is then pumped to the zinc stripping stage <NUM> and fed into a third stage contactor in which the Zn is stripped from the organic phase by a sulfuric acid solution. The aqueous concentrated strip ZnSO4 product liquor <NUM> then goes for further processing depending on the desired product form. The stripped solvent <NUM> is recycled back to the zinc extraction stage <NUM>.

The SX circuit <NUM> includes a manganese extraction stage <NUM>, a manganese scrubbing stage <NUM>, and a manganese stripping stage <NUM>. Similar to the zinc SX circuit, the raffinate containing Mn <NUM> and an organic solvent <NUM> (e.g., Cytex <NUM>) are fed in a counter-current manner into a first stage contactor in which the two phases are mixed and Mn is transferred from the aqueous phase into the organic phase. The manganese loaded solvent <NUM> is fed into a second stage contactor where it is scrubbed with a suitable aqueous solution <NUM> to remove small amounts of impurities remaining. After settling in the manganese scrubbing stage <NUM>, the scrub raffinate will be recycled to an appropriate stream <NUM>. The loaded solvent <NUM> is then pumped to the manganese stripping stage <NUM> and fed into a third stage contactor in which the Mn is stripped from the organic phase by a sulfuric acid solution. The aqueous concentrated strip MnSO4 product liquor <NUM> then goes for further processing depending on the desired product form. The stripped solvent <NUM> is recycled back to the manganese extraction stage <NUM>.

It is to be understood that the terms "including", "comprising", "consisting" and grammatical variants thereof do not preclude the addition of one or more components, features, steps, or integers or groups thereof and that the terms are to be construed as specifying components, features, steps or integers.

It is to be understood that where the claims or specification refer to "a" or "an" element, such reference is not be construed that there is only one of that element.

It is to be understood that where the specification states that a component, feature, structure, or characteristic "may", "might", "can" or "could" be included, that particular component, feature, structure, or characteristic is not required to be included.

Where applicable, although state diagrams, flow diagrams or both may be used to describe embodiments, the invention is not limited to those diagrams or to the corresponding descriptions. For example, flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described.

Systems and processes of the instant disclosure may be implemented by performing or completing manually, automatically, or a combination thereof, selected steps or tasks.

The term "process" may refer to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the art to which the invention belongs.

For purposes of the instant disclosure, the term "at least" followed by a number is used herein to denote the start of a range beginning with that number (which may be a range having an upper limit or no upper limit, depending on the variable being defined). For example, "at least <NUM>" means <NUM> or more than <NUM>. The term "at most" followed by a number is used herein to denote the end of a range ending with that number (which may be a range having <NUM> or <NUM> as its lower limit, or a range having no lower limit, depending upon the variable being defined). For example, "at most <NUM>" means <NUM> or less than <NUM>, and "at most <NUM>%" means <NUM>% or less than <NUM>%. Terms of approximation (e.g., "about", "substantially", "approximately", etc.) should be interpreted according to their ordinary and customary meanings as used in the associated art unless indicated otherwise. Absent a specific definition and absent ordinary and customary usage in the associated art, such terms should be interpreted to be ± <NUM>% of the base value.

When, in this document, a range is given as "(a first number) to (a second number)" or "(a first number) - (a second number)", this means a range whose lower limit is the first number and whose upper limit is the second number. For example, <NUM> to <NUM> should be interpreted to mean a range whose lower limit is <NUM> and whose upper limit is <NUM>. Additionally, it should be noted that where a range is given, every possible subrange or interval within that range is also specifically intended unless the context indicates to the contrary. For example, if the specification indicates a range of <NUM> to <NUM> such range is also intended to include subranges such as <NUM> -<NUM>, <NUM>-<NUM>, etc., <NUM>-<NUM>, <NUM>-<NUM>, etc., as well as any other possible combination of lower and upper values within the stated range, e.g., <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, etc. Note that integer range values have been used in this paragraph for purposes of illustration only and decimal and fractional values (e.g., <NUM> - <NUM>) should also be understood to be intended as possible subrange endpoints unless specifically excluded.

It should be noted that where reference is made herein to a process comprising two or more defined steps, the defined steps can be carried out in any order or simultaneously (except where context excludes that possibility), and the process can also include one or more other steps which are carried out before any of the defined steps, between two of the defined steps, or after all of the defined steps (except where context excludes that possibility).

Claim 1:
A process for recovering lithium from a natural or synthetic brine solution, said process comprising the steps of:
concentrating the lithium in the brine solution by cyclically and sequentially flowing the brine solution through a continuous countercurrent adsorption and desorption (CCAD) circuit to form an enhanced lithium product stream, and
recovering the lithium from the enhanced lithium product stream,
wherein said CCAD circuit comprises a central multi-port valve system, wherein said CCAD circuit comprising said central multi-port valve system further comprises a plurality of process zones, wherein each process zone comprises an adsorbent bed or column containing a lithium selective adsorbent, wherein said plurality of process zones further comprises:
a brine displacement zone positioned upstream with respect to fluid flow of a brine loading zone;
said brine loading zone positioned upstream with respect to fluid flow of and in fluid communication with an entrainment rejection zone;
said entrainment rejection zone positioned upstream with respect to fluid flow of and in fluid communication with an elution zone; and
said elution zone in fluid communication with said brine displacement zone, and
wherein said process further comprises the steps of:
a) displacing a lithium-containing feed brine solution from a freshly loaded adsorbent bed or column using a lithium product eluate and passing a displacement liquor solution to a brine feed inlet of a lithium adsorption zone;
b) incorporating said displacement liquor solution into said feed brine solution to form a combined liquor/feed brine solution;
c) passing said combined liquor/feed brine solution through a lithium loading zone where lithium is adsorbed on one or more loading adsorbent beds or columns and forming a lithium depleted brine raffinate;
d) displacing an eluate solution from said loading adsorbent beds with a portion of said lithium depleted brine raffinate from said lithium loading zone and into an elution zone;
e) flowing a fresh eluant solution through said elution zone stripping a portion of lithium adsorbed on said adsorbent beds or columns; and
f) collecting a portion of eluate having high lithium concentration as an enhanced lithium product solution.