A process and plant

Abstract

The present disclosure relates to a process and plant for desorbing lithium from a lithium enriched ion exchange material that is co-loaded with impurities. The lithium enriched ion exchange material is contacted with a solution under acid conditions to at least partially desorb lithium and, at least partially desorb impurities from the ion exchange material to provide a lithium eluate and a regenerated ion exchange material. In addition, the solution includes sulphate (ions) such that the desorption step includes at least a portion of the impurities desorbed from the ion exchange material precipitating as sulphate precipitates.

Description

A PROCESS AND PLANT RELATED APPLICATION

[0001] This application claims priority to Australian provisional application number 2023902808 entitled A PROCESS AND PLANT that was filed on 31 August 2023, the full contents of which is hereby incorporated into the present specification. FIELD

[0002] The present invention relates to a process and plant for recovering lithium, including desorbing lithium from a lithium enriched ion exchange material that is co-loaded with impurities. BACKGROUND

[0003] Lithium is an essential element for batteries and other technologies. Lithium is found in a variety of liquid resources, including natural and synthetic brines and leachate solutions from minerals, clays, and recycled products. The present disclosure relates to an alternative process and plant for recovering lithium. SUMMARY

[0004] An embodiment of the present invention relates to a process of recovering lithium, the process includes a desorption step for recovering lithium from a lithium enriched ion exchange material that is co-loaded with impurities, in which the desorption step includes: contacting the lithium enriched ion exchange material that is co-loaded with impurities with a solution under acid conditions to at least partially desorb lithium and, at least partially desorb impurities from the ion exchange material to provide a lithium eluate and a regenerated ion exchange material; wherein the solution includes sulphate (ions) such that the desorption step includes at least a portion of the impurities desorbed from the ion exchange material precipitating as sulphate precipitates, wherein the impurities include Group II metals including one or more of Ca (Calcium), Sr (Strontium) and Ba (Barium).

[0005] The desorption step may be carried out in one or more moving beds, such as a fluidised bed or an elutriating bed. The or each moving bed fluidises the precipitates and ion exchange material to reduce fouling and / or blockages during the desorption step. In addition, the moving bed allows conditions, such as pH, concentrations, and additives such as acids and alkalis to be homogeneous or near homogeneously mixed in the desorption step. In other words, the desorption step may not be carried out in a packed bed.

[0006] Precipitation of the sulphate precipitates may occur simultaneously (or concurrently) during the desorption step.

[0007] The sulphate precipitates contain at least a portion of the impurities that are desorbed from the ion exchange material.

[0008] It will be appreciated that an equilibrium will be reached in the solubility of the impurities dissolved in the solution and the sulphate precipitates. P0512WO

[0009] In one example, the impurities include Group II metals including at least two of Ca (Calcium), Sr (Strontium) and Ba (Barium).

[0010] In another example, the impurities include Group II metals including all three of Ca (Calcium), Sr (Strontium) and Ba (Barium).

[0011] The Group II metals may comprise Ca (Calcium), Sr (Strontium) and Ba (Barium). It is possible that the Group II metals may also include Ra (Radium). The sulphate precipitates of Calcium, Strontium and Barium being formed may include gypsum, celestite and barite. The sulphate precipitates will only include trace amounts of Be (Beryllium) and Mg (Magnesium). For instance, as Be (Beryllium) and Mg (Magnesium) have a high solubility in the conditions of the desorption step, it is possible that traces amounts of Be (Beryllium) and Mg (Magnesium) can be entrained in the sulphate precipitates.

[0012] The process may include discharging from the desorption step the lithium eluate and the sulphate precipitates in a single stream.

[0013] The process may include discharging the ion exchange material from the fluidised bed. The ion exchange material discharged may be partially depleted of lithium.

[0014] In one example, the process may include discharging from the desorption step the lithium eluate, depleted ion exchange material, and the precipitate from the fluidised bed.

[0015] The process may then include a separating step of separating the ion exchange material from the lithium eluate and the sulphate precipitate. The separating step may be a size separation performed using a screening device.

[0016] In one example, the ion exchange material may be discharged from the desorption step separately from the eluate and the precipitate. For example, the ion exchange material may be discharged from a bottom of a vessel in which the desorption step is carried out, for instance under gravity, or a top valve via a pulsing technique.

[0017] The ion exchange material may be coarser than the sulphate precipitate. For example, the ion exchange material may have a particle size of equal to or greater than 200μm. In another example, the ion exchange material may have a particle size from 200 to 2000μm. In another example, the ion exchange material may have a particle size from 500 to 2000μm.

[0018] The sulphate precipitates may be fine particles that are less than 200μm in size.

[0019] The process may include supplying the solution to the desorption step at a known flow rate.

[0020] The process may include washing regenerated ion exchange material discharged from the desorption step with washing water to form a first spent washing water, and using at least a portion of the first spent washing water as the solution in the desorption step. In one example, at least a portion of the spent washing water may be fed to the desorption step. In another example, all of the spent washing water may be fed to the desorption step.

[0021] The process may include a treatment step of treating the spent washing water to form a brine and a cleansed washing water. The portion of the spent washing water fed to the desorption step may P0512WObe the brine. The cleansed washing water may be reused as washing water together with optional make up washing water.

[0022] The treatment step may be a concentrating step in which the first spent washing water is concentrated to form the brine, and the cleansed washing water.

[0023] The treatment step may be a reverse osmosis treatment in which permeate of the treatment provides the cleansed washing water, and the concentrate provides the brine supplied to the desorption step for use the solution in the desorption step.

[0024] The process may include controlling the pH during the desorption step so as to provide free H+ions to facilitate desorption of lithium and the impurities from the exchange material.

[0025] In one example, controlling the pH includes adding sulphuric acid to the desorption step so that desorption step is carried out under conditions with 0.031 to 0.071 g / L free H+ions. In another example, free H+ions may be at a concentration of approximately 0.051 g / L in the desorption step. A possible benefit in adding sulphuric acid to provide the free H+ions, is that the H+ions can replace the Li+ions (and impurities) on the ion exchange material during desorption, whilst a portion of the sulphate ions from the sulphuric acid can form a salt precipitate with the impurities desorbed from the ion exchange material.

[0026] In addition, the process may include adding an alkali sulphate to a desorption step to provide sulphate anions for forming the sulphate precipitate. For example, adding alkali sulphate may include adding a solution including one or more of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4), potassium sulphate K2SO4and ammonium sulphate (NH4)2SO4to the desorption step.

[0027] Moreover, acids other than sulphuric acid can be used when alkali sulphates are added to the desorption step. For example, hydrochloric acid may also be added to the desorption step. In addition, a mixture of acids such as sulphuric acid and hydrochloric acid may be added to the desorption step, in which case alkali sulphate may also be added to the desorption step.

[0028] The step of controlling the pH should avoid lowering the pH below a threshold that can cause damage to the ion exchange material. For instance, when the conditions of the desorption step become too acidic, the ion exchange material could be weakened or even partially or fully dissolve.

[0029] The process may also include controlling the oxidation / reduction potential (ORP) of either one or both of the desorption step and the adsorption step. One possible reason for controlling ORP would be to preserve the longevity of the ion exchange material. By way of example, ozone, hydrogen peroxide or persulphate ions may be added as an oxidant. Examples of other chlorine containing oxidants include Cl2, NaOCl, or ClO2. Similarly, sulphur dioxide or metabisulphite may be added as a reductant.

[0030] The process may also include controlling the flow rate and / or volume of an acid solution fed to the desorption step, and thereby reduce dilution of the lithium eluate discharged from the desorption step. Controlling the flow rate of the acid solution may be carried out by selecting the concentration of the acid solution. Increasing the concentration of the acid solution can reduce the flow rate of the acid solution without changing the acidity of the desorption step. P0512WO

[0031] The process may also include controlling the flow rate of the solution fed to the desorption step, and thereby reduce dilution of the lithium eluate discharged from the desorption step.

[0032] This has two possible benefits including, increasing the yield of sulphate precipitates from the lithium eluate, which reduces the amount of impurities in the recovered lithium eluate. In addition, this also increases the concentration of the lithium recovered. An increased lithium concentration and decreased mass of soluble impurities in the recovered eluate can reduce downstream operating and equipment costs.

[0033] The process may include separating the lithium eluate from the sulphate precipitates to produce a lithium product solution and a solid product containing impurities.

[0034] The desorption step may be carried out in multiple sub-stages, that is in at least two sub- stages, in which the freeconditions of at least two sub-stages is controlled so that the free H+conditions are different the sub-stages. For example, the free H+in a first sub-stage in which the ion exchange material may be treated to desorb lithium and impurities, can be lower than the free H+conditions in subsequent stages of the desorption step. That is to say the pH conditions in the first substage can be higher than the pH in the subsequent sub-stage.

[0035] The desorption step may be carried in multiple sub-stages, where the lithium enriched ion exchange material is supplied to a previous sub-stage, (in which the desorption step is carried out), and at least partially depleted ion exchange material is discharged from the previous sub-stage and supplied to at least one subsequent sub-stage (in which the desorption step is carried out) defining a direction of movement of the ion exchange material between the sub-stages, and the solution is conveyed in counter current from the at least one subsequent stage to the respective previous stage. The ion exchange material and the solution may be separated between each sub-stage. That is to say, the process includes discharging a slurry from the at least one subsequent sub-stage, the slurry including the ion exchange material, the sulphate precipitates and the lithium eluate, and the process includes separating the ion exchange material from the lithium eluate and the sulphate precipitates, and supplying the lithium eluate and the sulphate precipitate to the previous sub-stage to provide the solution.

[0036] The process may also include discharging the slurry from the first sub-stage, the slurry including the ion exchange material, the solution including sulphate precipitates and the lithium eluate, and the process includes separating the ion exchange material from the solution, and the process includes an additional separating step in which the lithium eluate and the sulphate precipitates are separated into a lithium product solution and a solid product containing the impurities. For example the additional separating step may be by filtration, such as sand filtration.

[0037] The solution being conveyed from the subsequent sub-stage to the previous sub-stage (in the opposite direction of flow of the ion exchange material) may be the lithium eluate discharged from the subsequent sub-stage.

[0038] The lithium eluate and the ion exchange material discharged from each sub-stage may be separated.

[0039] In one example, the ion exchange material may be discharged from one or more sub-stage as separate streams of the ion exchange material and the eluate. For example, the ion exchange material P0512WOmay be discharged from a lower region of the sub-stage, and the eluate may be discharged from an upper region of the sub-stage.

[0040] In another example, the ion exchange material may be discharged from the or each as a single stream, and the ion exchange material separated from eluate include the sulphate precipitates based on the sizing. For example, the ion exchange material may be held up on sizing screen and the eluate and precipitates may pass.

[0041] The process may or may not include separating the sulphate precipitate from a solution in an intermediate step prior to the stream being passed from the subsequent sub-stage to a previous sub- stage.

[0042] In one example, one or more of the sub-stages may include a single fluidised bed. The fluidised bed may be divided into subsections.

[0043] The step of controlling the pH may include the pH of the subsequent sub-stage being lower than the pH in the previous sub-stage. That is a higher concentration of acid in the subsequent sub- stage to drive more efficient desorption.

[0044] The desorption step may be carried out in any suitable temperature range, and suitably ambient temperature in the range of 10 to 40ºC, and even more suitably in the range of 15 to 35 ºC.

[0045] The desorption step may be carried out for any reasonable residence time and suitably the total residence time is in the range of 1 to 10 hours, and preferably in the range of 3 to 5 hours. It will be appreciated that the residence time will depend on the size of the desorption sub-stages.

[0046] The process may also include an adsorption step in which a lithium feed liquid containing dissolved lithium and the impurities are sorbed by the ion exchange material, wherein the adsorption step includes contacting the ion exchange material and the lithium feed liquid under pH controlled conditions to load the ion exchange material. That is to say, the adsorption step includes contacting the lithium feed liquid with the regenerated ion exchange material under controlled pH conditions to sorb lithium and sorb at least a portion of the impurities including Ca (Calcium), Sr (Strontium), and Ba (Barium) to provide the lithium enriched ion exchange material.

[0047] A depleted lithium liquid can be discharged from the adsorption step. Optionally, the depleted lithium liquid can be returned to the origin of the lithium feed liquid.

[0048] The process may include controlling the pH conditions of the adsorption step to a pH in range of 5 to 9. In one example, the process may include controlling the pH in the range of 5 to 8, or 5 to 7, or 5 to 6. In another example, the process may include controlling the pH in the range of 6 to 9, or 7 to 9 or 8 to 9.

[0049] In another example, the process may include controlling the pH conditions of the adsorption step to be alkaline, such as in the range from, 7 to 9.

[0050] The adsorption process may include adding a base / alkali to the adsorption step. For example, the base may be in the form of calcium hydroxide (Ca(OH)2), sodium hydroxide (NaOH) and so forth.

[0051] One of the benefits in using calcium hydroxide is that a calcium sulphate precipitate (e.g. gypsum, CaSO4.2H2O) can be formed which can be separated from the depleted lithium liquid. P0512WO

[0052] The adsorption step may be carried out in the two or more sub-stages in which the lithium feed liquid is supplied to a first or preceding adsorption sub-stage and a (partially) depleted lithium feed liquid is supplied from the preceding adsorption sub-stage to a subsequent adsorption stage, and the ion exchange material is conveyed in counter current between the sub-stages from the subsequent adsorption sub-stage to the preceding adsorption sub-stage.

[0053] The adsorption step may be carried out in any suitable temperature range, and suitably at a temperature in the range of 10 to 80ºC, and even more suitably in the range of 50 to 70ºC.

[0054] The adsorption step may be carried out for any reasonable residence time and suitably the total sorbent residence time is in the range of 6 to 24 hours, and preferably in the range of the 10 to 15 hours. It will be appreciated that the residence time will depend on the size of the adsorption stages.

[0055] The lithium rich ion exchange material may have from 2,000 to 17,000 mg / kg of Lithium sorbed onto the ion exchange material. Suitably, the lithium rich ion exchange material may have from 3,000 to 17,000 mg / kg of Lithium sorbed onto the ion exchange material, or from 3,500 to 17,000 mg / kg of Lithium sorbed onto the ion exchange material.

[0056] The process may include separating the ion exchange material and the partially depleted lithium feed liquid between the adsorption sub-stages.

[0057] The ion exchange material and the partially depleted lithium feed liquid may be separated in a separating step. The separating step may be carried out as a screen separation in which the ion exchange material is held on the screen and the (partially) depleted lithium feed liquid and precipitate (if present) passes through the screen.

[0058] The adsorption stages may be a moving bed, such as fluidised bed, an agitated bed, or an elutriating bed. That is say, the adsorption sub-stages may be the moving beds.

[0059] The process may include washing the lithium enriched ion exchange material with wash water to remove lithium feed liquid (rich in impurities) from the ion exchange material to provide a spent washing water.

[0060] The process may include adding at least a portion of the spent washing water to the feed lithium liquid.

[0061] The process may include adding all of the spent washing water to the feed lithium liquid.

[0062] The process may include a step of treating the spent washing water to provide a concentrated brine which can be added to the feed liquid, and the cleansed washing water that can be used as the washing water with optional makeup wash water.

[0063] The step of treating the spent washing water may include a reverse osmosis treatment in which a permeate of the treatment provides the cleansed washing water and concentrated RO brine. The RO brine can be added to the lithium feed liquid.

[0064] An embodiment of the present invention relates to a process of desorbing lithium from a lithium enriched ion exchange material that is co-loaded with impurities, the process includes: P0512WOcontacting the lithium enriched ion exchange material with an acidic solution, to at least partially desorb lithium and to at least partially desorb impurities from the ion exchange material to form an eluate, wherein the ion exchange material contacts the acidic solution in a fluidised operation in the presence of sulphate (as ions or salts); forming precipitates including a sulphate salt of the impurities in the fluidised bed, hereinafter the sulphate precipitates, wherein the impurities include Group II metals including one or more of Ca (Calcium), Sr (Strontium), Ba (Barium); and discharging the eluate and the precipitates from the fluidised bed.

[0065] An embodiment of the present invention relates to a plant for recovering lithium, the plant includes at least one desorption stage for recovering lithium from a lithium enriched ion exchange material that is co-loaded with impurities, the desorption stage being configured to receive the lithium enriched ion exchange material that is co-loaded with impurities and receive a solution that contacts the lithium enriched ion exchange material under acidic conditions to at least partially desorb lithium to provide a lithium eluate and at least partially desorb impurities from the ion exchange material to form an at least partially regenerated ion exchange material, wherein the impurities include Group II metals including one or more of Ca (Calcium), Sr (Strontium) and Ba (Barium), and the desorption stage is configured so that sulphate ions in the solution reacts with the impurities desorbed from the ion exchange material to form sulphate precipitates in the desorption stage

[0066] The desorption stage may be configured as a moving bed in which the ion exchange material and the sulphate precipitates are fluidised.

[0067] The plant may include a washing stage in which the at least partially regenerated ion exchange material is washed with washing water, and has an ion exchange material outlet from which regenerated ion exchange material is discharged, and a water outlet from which a first spent wash water is discharged.

[0068] The plant may include a first reverse osmosis treatment stage having an inlet that receives the first spent wash water, and a brine outlet that discharges brine, the brine outlet being connected to the desorption stage so the brine can be used as the solution that contacts the lithium rich ion exchange material in the desorption stage, and a permeate outlet that discharges a permeate.

[0069] The plant may include a first pH sensor that senses the acidity of the desorption stage, an acid source including an acidic solution, and a first controller that controls the supply of the acidic solution to the desorption stage based on an output signal of the pH sensor that is received by the first controller.

[0070] The controller may include controlling the flow rate and / or volume of the acid solution fed to the desorption stage.

[0071] The plant may include an alkali sulphate source having sulphate solution including one or more of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4), potassium sulphate K2SO4 and ammonium sulphate (NH4)2SO4, and the plant includes a conduit for supplying the sulphate solution to the desorption stage. P0512WO

[0072] The plant may include at least two of the desorption sub-stages, in which a first desorption sub-stage, hereinafter referred as the previous stage, is configured to receive the lithium enriched ion exchange material, and at least partially depleted ion exchange material is discharged from the previous sub-stage and supplied to at least one subsequent sub-stage defining a direction of movement of the ion exchange material between the previous sub-stage to the subsequent sub-stage, and the solution is conveyed in counter current from the at least one subsequent sub-stage to the respective previous sub-stage.

[0073] The or each desorption sub-stage may include an outlet that discharges a slurry including the ion exchange material, sulphate precipitates and the solution including lithium eluate, and the or each desorption sub-stage has a stage separator that separates the ion exchange material from the sulphate precipitates and the solution.

[0074] The stage separator may be configured to separate the ion exchange material from the sulphate precipitates and the solution by holding the ion exchange material on a screening device, and the solution and the precipitates pass through screening device.

[0075] The screening device may have openings that are sized for holding the ion exchange material that is equal to greater than 200µm in size.

[0076] The washing stage may be configured to receive the ion exchange material discharged from the stage separator of the subsequent stage that is arranged last in the movement direction of the ion exchange material.

[0077] The plant may include a precipitates separator that is configured to receive the sulphate precipitates and the solution including lithium eluate from the stage separator of the previous desorption sub-stage arranged first in the movement direction of the ion exchange material, the precipitates separator separating the precipitates from the solution to produce a lithium product solution and solid product containing the impurities.

[0078] The plant may include an adsorption stage that has a feed inlet that receives a lithium feed liquid containing dissolved lithium and the impurities, and the regenerated ion exchange material, and the adsorption stage is configured to be operated under controlled pH conditions so that the ion exchange material sorbs lithium and at least a portion of the impurities, including Ca (Calcium), Sr (Strontium), and Ba (Barium) from the lithium feed liquid to provide the lithium enriched ion exchange material.

[0079] The plant may include a base / alkali source that supplies a base / alkali to the adsorption stage.

[0080] The plant may include a second pH sensor that senses the pH in the adsorption stage and a second controller that controls the supply of the base / alkali based on an output signal of the second pH sensor received by the second controller.

[0081] The adsorption stage may include at least two adsorption sub-stages in which the lithium feed liquid is supplied to a first or preceding adsorption stage and a (partially) depleted lithium feed liquid is supplied from the preceding adsorption stage to a subsequent adsorption stage, and the ion exchange material is conveyed in counter current between the stages from the subsequent adsorption stage to the preceding adsorption stage. P0512WO

[0082] The or each adsorption sub-stage may be a moving bed.

[0083] The or each adsorption sub-stage may include a material separator for separating the ion exchange material and the partially depleted lithium feed liquid.

[0084] The material separator may be configured to discharge ion exchange material and supply the ion exchange material to the subsequent adsorption sub-stage (in the direction of flow of the ion exchange material), and is configured to supply the partially depleted lithium feed liquid to the preceding adsorption sub-stage (in the direction of flow of the ion exchange material).

[0085] The plant may include a second washing stage that is configured to wash the lithium enriched ion exchange material discharged from the adsorption stage with washing water to remove lithium feed liquid from the ion exchange material which provides a second spent washing water.

[0086] The plant may include a second reverse osmosis treatment stage having an inlet that receives the second spent wash water, a concentrate outlet that discharges a concentrated RO brine, the concentrate outlet being connected to a line supplying the lithium feed liquid so the concentrated RO brine can be added to the lithium feed liquid, and a permeate outlet.

[0087] The plant may include any one or a combination of the features of the process described herein. Similarly, the process described herein may also include any one or a combination of the features of the plant described herein.

[0088] The term “moving bed” or variations thereof embraces any mixed bed or fluidised bed including an air agitated bed, a sparged bed, a counter current bed in which the ion exchange material and the solution flow in opposite directions, and / or mechanically agitated bed. The moving bed may also include an elutriation bed.

[0089] The term “lithium feed liquid” or variations thereof, embraces any lithium containing liquid resource, including, but by no means limited to, a natural brine, ground water, a dissolved salt flat salar, seawater, concentrated seawater, a geothermal brine, a desalination effluent, a concentrated brine, a processed brine, an oilfield brine, a liquid from an ion exchange process, a liquid from a solvent extraction process, a synthetic brine, a leachate from an ore or combination of ores, a leachate from a mineral or combination of minerals, a leachate from a clay or combination of clays, a leachate from recycled products, a leachate from recycled materials such as lithium batteries, or combinations thereof. BRIEF DESCRIPTION OF THE FIGURES

[0090] These and other features, aspects, and characteristics of the present disclosure are described with reference to the drawings of certain embodiments, which are intended to schematically illustrate certain embodiments and not to limit the disclosure. The accompanying Figures may be summarised as follows.

[0091] Figure 1 is a flow diagram of a process and plant for recovering lithium from an ion exchange material loaded with the lithium and co-loaded with impurities, the process and plant including a desorption step that produces a product liquid that is rich in lithium, according to a preferred embodiment. P0512WO

[0092] Figure 2 is a flow diagram of a process and plant for recovering lithium, in which the process and plant includes an adsorption step for recovering lithium from a feed liquid containing lithium by adsorbing lithium onto the ion exchange material to produce a lithium enriched ion exchange material according to the preferred embodiment. The lithium enriched ion exchange material can then be treated in the desorption step according to the flow diagram in Figure 1.

[0093] Figure 3 is an example of a stage of the desorption step in the form of an elutriation column in which ion exchange material is discharged from a bottom of the column and a slurry containing lithium eluate and sulphate precipitates are discharged from the top of the column. DETAILED DESCRIPTION

[0094] A preferred embodiment of the present invention will now be described with reference to the accompanying drawings. The following text describes a process 10 and plant 11 with reference numerals that identify the features in the Figures. In the case where the process 10 and plant 11 have corresponding features, the same references numerals have been used to denote features of the process 10 and the plant 11. A reference numeral table is provided at the end of the detailed description.

[0095] Figure 1 relates to a desorption step 12 of a process 10 and plant 11 for recovering lithium from a lithium rich ion exchange material 28 loaded with lithium and impurities. The impurities include any one or a combination of Group II metals, such as Ca (Calcium), Sr (Strontium), Ba (Barium) and Ra (Radium). The desorption step 12 comprises multiple desorption stages which in the preferred embodiment comprises Desorption stage 1D, Desorption stage 2D and Desorption stage 3D. Any suitable number of stages can be provided. Each desorption stage 1D, 2D and 3D may have one or more moving bed, such as a fluidised bed or an agitated bed (as represented in Figure 1), or an elutriating bed as represented in Figure 3. Lithium and impurities are desorbed from the ion exchange material progressively and an ion exchange material stream 13 is conveyed from the first stage, Desorption sub-stage 1D, to a subsequent sub-stage, Desorption sub-stage 2D, and then to the last sub-stage, Desorption sub-stage 3D, which defines the direction of flow of the ion exchange material represented by the dashed lines. A solution 14 flows in an opposite direction, that is in a counter current direction to the ion exchange material, from Desorption sub-stage 3D to Desorption sub-stage 2D and from Desorption sub-stage 2D to Desorption sub-stage 1D.

[0096] Regenerated ion exchange material 15 may be washed in a washing step 16 prior to being reused in an adsorption step shown in Figure 2. The washing step 16 may be carried out in any suitable washing vessel, including a moving bed or a non-moving bed. The washing step 16 includes passing washing water over the ion exchange material to wash acid and any lithium or impurities from the surface of the ion exchange material, including interstitial liquid, and acid and lithium and impurities entrained in the pores of the ion exchange material. Spent washing water 17 is discharged from the washing step 16 may then be treated in a concentrating step 18 to produce a brine solution 19 and a purified washing water 20. The concentrating step 18 may be any suitable treatment including a reverse osmosis in which the RO permeate is the purified washing water 20, and RO concentrate is the brine solution 19. The purified washing water 20 may be recycled back to the washing step 16 and, when required, make up water 21 can be added. The brine solution 19, which provide part or all of solution stream 14, can be fed to the last Desorption sub-stage 3D, where the ion P0512WOexchange material is fluidised in the presence of an acid. A stream 13 of partially depleted ion exchange material is added to Desorption sub-stage 3D from Desorption sub-stage 2D.

[0097] The acid 22, suitably concentrated sulphuric acid, H2SO4, is added to Desorption sub-stage 3D progressively to control the pH so that lithium and impurities are replaced on the ion exchange material with H+ions supplied by the acid 22. Any acid supplying H+ions can be used, including hydrochloric acid. However, one of the benefits in using sulphuric acid is that the sulphate ions can form complexes with desorbed impurities, including salts of Ca (Calcium), Sr (Strontium), Ba (Barium), including gypsum, celestite and barite. Ra (Radium) may also be an impurity. These impurities have a low solubility and may precipitate in the desorption step 12 with sulphate. In the situation where sulphuric acid is not used as the acid, or if insufficient sulphate ions are available relative to the impurities desorbed, additional sulphate can be added to the desorption step 12. This is not shown in Figure 1. For example, alkali sulphates such as one of a combination of sodium sulphate Na2SO4, magnesium sulphate MgSO4, ammonium sulphate (NH4)2SO4and potassium sulphate K2SO4can be added to the desorption step 12.

[0098] As shown in Figure 1, a third slurry 23 and a regenerated ion exchange material 15 depleted of lithium and impurities is discharged from Desorption stage 3D, optionally as a single stream, and a (third) separating step 24 separates ion exchange material from a slurry containing sulphate precipitates, the brine solution, and the lithium eluate. The separating step 24 may be carried out by a screen on which the ion exchange material is held up, and the solution 14 including the lithium eluate and the sulphate precipitates pass through the screen. Specifically, the ion exchange material may have a particle size of equal to or greater than 200μm, and the sulphate precipitates are fines smaller than the ion exchange material. The solution 14 is then supplied to the previous desorption stage, namely Desorption stage 2D. After the separation step 24, the regenerated ion exchange material 15 is fed to the washing step 16. The desorption procedure for Desorption sub-stage 3D is repeated in Desorption sub-stage 2D, including acid 22 being added progressively under controlled pH conditions, additional sulphate can be added as required, and lithium and impurities are desorbed from the partially regenerated ion exchange material. The desorption step 12 includes the formation of additional precipitates, and the Desorption sub-stage 2D can be operated as a fluidised bed.

[0099] Partially depleted / partially regenerated ion exchange material 25 and a second slurry 26 formed in the Desorption sub-stage 2D are discharged and separated in a second separating step 27. After separation, the second slurry 26 including the solution 14 containing lithium eluate, dissolved acid, and the sulphate precipitates are fed to Desorption sub-stage 1D of the desorption step 12 and the partially depleted / regenerated ion exchange material 13 is fed to the Desorption sub-stage 3D. The lithium rich ion exchange material 28, which may or may not have been washed from the adsorption step shown in Figure 2 is fed to the Desorption sub-stage 1D, together with an acid 22, and optionally, sulphate ions as described above in relation to Desorption sub-stages 3D, 2D and 1D. Specifically, the acid facilitates desorption from the ion exchange material and the sulphate facilitates precipitation of impurities as sulphate salts or complexes.

[0100] A first slurry 29 and partially depleted / partially regenerated ion exchange material 25 is discharged from Desorption sub-stage 1D and processed in a first separation step 30 which separates the ion exchange material 25 and the first slurry 29 comprising rich lithium eluate and the sulphate precipitates. When free of the ion exchange material, the first slurry 29 undergoes a further P0512WOseparation step 31 to separate the rich eluate and the sulphate precipitates to produce a product stream 32 and precipitated impurities 33. The further separation step 31 may be any suitable mass separation step such as sedimentation, or a particle size separation step such as filtration. Although not shown in Figure 1, the precipitated impurities 33 may be washed to recover entrained lithium.

[0101] We have realised that the precipitates formed in the desorption step 12 are in these circumstances fine, generally less than 200μm, which means that the precipitates can be separated from the ion exchange material, which has a size equal to or greater than 200μm using a sizing separation. The ion exchange material may have a particle size in the range of 500 to 2000μm. Examples of a suitable sizing separation for separating steps 24, 27 and 30 include is a screen separator or an elutriation separator.

[0102] In addition, the process 10 includes controlling the acidic conditions in which the desorption step 12 is carried out to achieve adequate desorption from the lithium rich ion exchange material 28 and preserve the longevity of the ion exchange material for repeated reuse between the adsorption and desorption steps over a suitable period. The acid level in the later stage(s) of the desorption step 12 such as Desorption sub-stage 3D, is ideally stronger than acid levels in the earlier stage(s) of the desorption step, such as Desorption sub-stage 1D. For example, the acid level in the later stage(s) of the desorption step 12, which in the case of Figure 1 comprises Desorption sub-stages 2D and 3D, may be measured in terms of free sulfuric acid in solution which is preferably in the range from 0.03 to 0.071g / L free H+ions, and optionally, approximately 0.05 g / L of free H+ions. In the case of the earlier stage(s) of the desorption step 12, which in the case of the Figure 1 comprises Desorption sub-stage 1D, the acidity of the desorption step 12 may be less than 0.05 g / L of free H+ions, and optionally in the range of 0.01 to 0.05g / L of free H+ions. A possible benefit in having the conditions in the Desorption sub-stage 1D less acidic is that neutralisation, or the degree of neutralisation, in downstream processing of the product 32 may be reduced. Ultimately, the acidity of the desorption step 12, and the individual desorption stages will depend on the properties of the ion exchange material and possibly other downstream requirements of the product stream 32.

[0103] The process 10 also includes controlling dilution of the lithium eluate during the desorption step 12. This can possibly provide several benefits including, increasing yield of the sulphate precipitates, which in turn reduces the amount of the impurities in the product stream 32. In addition, it also enables the product stream 32 to be more concentrated in recovered lithium which can reduce downstream operating expenses and capital expenses.

[0104] Controlling dilution of the lithium eluate can include controlling the volumetric flow rate of the RO brine 19 fed to the desorption step 12, namely the final Desorption sub-stage 3D or any of the Desorption sub-stages 1D to 3D. In addition, controlling dilution of the lithium eluate can include controlling the volumetric flow rate of the acidic solution 22 added to each sub-stage of the desorption step 12. Controlling the volumetric flow rate may include selecting or adjusting the concentration of the acid solution 22 added to each desorption sub-stage 1D to 3D. The residence time of the solution in each desorption sub-stage 1D to 3D will depend on factors including mixing and fluidisation of the desorption step 12, and the flow rate of the ion exchange material in the desorption step 12. Generally speaking, the residence time of the ion exchange material in the desorption step 12 may in the range of 1 to 10 hours, and suitably 4 to 6 hours, and for example approximately 5 hours. P0512WOHowever, the residence time will depend on the circumstances and the size of the desorption sub- stages 1D, 2D and 3D.

[0105] The desorption step 12 may be carried out in any suitable temperature range, and suitably ambient temperature in the range of 10 to 40ºC, and even more suitably in the range of 15 to 35ºC.

[0106] The desorption step 12 can be operated as a moving bed, such as a fluidised bed, an agitated bed, or an elutriation bed to prevent fouling or blockage of the desorption step 12, particularly in view of the formation of the sulphate precipitates. That is to say, each of the sub-stages 1D, 2D and 3D may be a moving bed. Although not shown in detail in Figure 1, the moving bed may be mechanically agitated, or air agitated by blowing air into the bottom of the bed. Ideally, the ion exchange material can withstand the mechanical loads during the desorption step 12, and may for example, sustain less than a loss of 10% according to a ball mill test due to attrition and percussive action.

[0107] The ion exchange material may be any suitable ion exchange material that is selective for lithium. Generally speaking the ion exchange material comprises inorganic Li-selective components which are held together by a binder. An example of a suitable ion exchange material that has active Li- selective material comprises a mixture of Mn(III) / Mn(IV) / Al oxide which are held together with a non- active polymer binder. Another example is an ion exchange material having an active Li-selective material comprises titanium or manganese, or combination thereof, and a binder. The binder may be organic, such as polymer, or inorganic such as a silica. By way of the example, Xtralit Ltd of Israel can supply suitable ion exchanger materials. These ion exchange materials have a lithium loading capacity greater than 5,000 mg / kg, and suitably a capacity up to 50,000 mg / kg. Suitably the lithium rich ion exchange material has a lithium loading in the range of 2,000 to 17,000 mg / kg of Lithium sorbed onto the ion exchange material. Suitably, the lithium rich ion exchange material may have from 3,000 to 17,000 mg / kg of Lithium sorbed onto the ion exchange material, or from 3,500 to 17,000 mg / kg of Lithium sorbed onto the ion exchange material.

[0108] Figure 2 illustrates the adsorption step 35 which comprises contacting the regenerated, or a partially regenerated, ion exchange material 15 with a feed lithium liquid 36 over multiple stages. In the case of Figure 2, the adsorption step 35 is carried out over three stages, namely, Adsorption sub- stage 1A, Adsorption sub-stage 2A and Adsorption sub-stage 3A. The lithium feed liquid 36 is passed sequentially from Adsorption sub-stage 1A to Adsorption sub-stage 2A to Adsorption sub-stage 3A, whereas the ion exchange material 15 moves between the stages in the opposite direction from Adsorption sub-stage 3A to Adsorption sub-stage 2A to Adsorption sub-stage 1A to progressively load the ion exchange material at each sub-stage 1A, 2A and 3A, with lithium and if present, impurities such as one or a combination of Ca (Calcium), Sr (Strontium), Ba (Barium) and Ra (Radium). A loaded ion exchange material 28 enriched with lithium and co-loaded with impurities is discharged from Adsorption stage 1A and fed to the first Desorption stage 1D in Figure 1.

[0109] The process 10 may include controlling the alkalinity of each of the adsorption sub-stages 1A to 3A by adding an alkali 49 to each adsorption sub-stage 1A to 3A. This may be carried out by adjusting the amount of the alkali added. A suitable alkali is calcium hydroxide Ca(OH)2. The alkali neutralises the H+desorbed from the ion exchange material, and helps to maintain the adsorption step 35 within a suitable pH range for the ion exchange material. P0512WO

[0110] Depending on the composition of the feed lithium liquid 36, calcium sulphate, i.e. gypsum, may or may not precipitate during the adsorption step 35. Gypsum is a fine precipitate and has a particle size less than 200μm which allows it to be separated from the ion exchange material, which has a larger size using screen separators or by elutriation. Specifically, as can be seen in Figure 2, intermediate streams 37 which may or may not be a slurry containing the feed lithium liquid 36 and precipitates, if any, are discharged from Adsorption sub-stages 1A and 2A together with the ion exchange material 28 and 38. The ion exchange material 28 and 38 is separated from the intermediate streams 37 in first and second separation steps 40 and 41 respectively. The intermediate stream 37 containing a depleted portion of the feed lithium liquid 36 can be fed successively to the Adsorption sub-stages 2A and 3A respectively. The final liquid / slurry 39 is discharged from Adsorption stage 3A and passes through a final separation step 42 to produce a discharge liquid 43 that is depleted in lithium and Group II impurities including any one or a combination of Ca (Calcium), Sr (Strontium), Ba (Barium) and Ra (Radium). In addition, it will be appreciated that other impurities, particularly those that are soluble over the pH range of the adsorption step 35, such as Boron (B) and Sodium (Na), may also be adsorbed by the ion exchange material and, as a result depleted from the discharge liquid 43 compared to the feed lithium liquid 36. In any event, the volumetric flow of the discharge liquid 43 is likely to be similar to the volumetric flow of the feed lithium liquid 36. This may provide the possible advantage of allowing the discharge liquid 43 to be returned to the origin of the feed lithium liquid 36 with minimal environmental impact.

[0111] The adsorption step 35, including Adsorption sub-stages 1A to 3A, can be operated as a moving bed, including a fluidised bed that may be agitated by mechanical means or by air blowing. Operation as a fluidised bed may be preferred if gypsum is precipitated. The adsorption step 35 may also be operated as a fixed bed. The residence time of the ion exchange material in the adsorption step 35 will depend on the selectivity and affinity of the ion exchange material for lithium. Generally speaking, the feed lithium liquid 36 may have residence time in the adsorption step 35 ranging from 1 to 3 hours, and suitably from 1.5 to 2.5 hours, or from 0.5 hour to 1 hour per adsorption sub-stage 1A to 3A. In contrast, the ion exchange material may have residence time in the adsorption step 35 ranging from the 10 to 24 hours, and suitably a total residence time is in the range of 6 to 24 hours, and preferably in the range of the 10 to 15 hours. It will be appreciated that the residence time will depend on the size of the adsorption sub-stages. The adsorption step may be carried out in any suitable temperature range, and suitably at a temperature in the range of 10 to 80ºC, and even more suitably in the range of 50 to 70ºC.

[0112] The loaded ion exchange material may be washed in a cleansing step 44 with washing water 45 which produces a spent wash water 46. Part of, or all of, the spent wash water 46 may be added to the feed lithium liquid 36. In addition, the spent wash water 46 may be treated to produce a concentrated brine 47 which may be added to the feed lithium liquid 36, and a purified water 48 which may be added to the washing water 45. The treatment may be a reverse osmosis in which the RO permeate provides the purified water 48 and the RO brine provides the concentrated brine 47. The purpose of the washing step 44 is to displace feed lithium liquid 36 containing impurities, mainly Ca, Na and K with a washing water containing low levels of impurities, to reduce transfer of the impurities from the adsorption step 35 to the desorption step 12.

[0113] The desorption and adsorption steps 12 and 35 may be carried out in stages as shown in Figures 1 and 2 respectively. Each of the Desorption and Adsorption sub-stages 1D, 2D and 3D, and 1A, P0512WO2A and 3A may include one or more moving beds. The moving beds may be characterised by fluidisation of its contents by means of counter current movement of the ion exchange material and the liquid within the bed. In addition to, or instead of the movement of the ion exchange material and liquid within the bed, the beds may also include mechanically agitated or air agitated, as mentioned above. For example, the desorption step 12 could be carried out in a single stage. In this example, the desorption sub- stages 1D, 2D and 3D, illustrated in Figure 1 could be replaced with the single stage. The steps carried out in relation to the desorption stages 1D, 2D and 3D, can be carried out in relation to a single sub-stage, or any number of the sub-stages. The desorption step 12 can be carried out in a single stage and can be described as follows using the reference numerals in Figure 1 although the desorption step 12 carried out as single stage is not illustrated in the Figures. Specifically, the desorption solution 14 can be at least partially provided by the brine 19 obtain from the spent wash water 17, for example by concentrating the spent wash water in a reverse osmosis treatment. The desorption solution can then be fed to the single stage to provide at least part of the desorption solution 14. The lithium rich ion exchange material 28 can be fed to the same stage, together with an acid solution, suitably sulphuric acid to control pH as described above to desorb lithium and impurities from the ion exchange material. As described above the acid solution can be added progressive during the desorption step 12. Similarly, optional alkali sulphate including one or more of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4), potassium sulphate K2SO4 and ammonium sulphate (NH4)2SO4 can also be added to ensure desorbed impurities can be precipitated. A slurry including regenerated ion exchange material 15, impurity precipitates and lithium eluate can be discharged from the single stage desorption step 12, and ion exchange material separated from the impurities based on size. The lithium eluate can also be separated from the impurity precipitates.

[0114] Figures 1 and 2 also illustrate a plant 11 for recovering lithium, which includes a desorption stage 12 in which lithium is recovered from a lithium rich ion exchange material 28 loaded with lithium and impurities, and an adsorption stage 25 in which lithium is loaded onto the ion exchange material. The plant 11 may include any one or a combination of the features of the process.

[0115] The plant 11 includes at least one desorption sub-stage, which as shown in Figure 1 comprises three desorption sub-stages, namely Desorption sub-stage 1D, Desorption sub-stage 2D and Desorption sub-stage 3D. However, it will be appreciated that any number of sub-stages can be provided. Each of the desorption sub-stages 1D, 2D and 3D are configured to include an inlet for receiving ion exchange material, with Desorption sub-stage 1D being configured to receive the lithium rich ion exchange material, and then move to Desorption sub-stage 2D and then to Desorption sub- stage 3D. A solution 14 flows in the opposite direction from Desorption sub-stage 3D to Desorption sub-stage 2D and then to Desorption sub-stage 1D. An acid source 50 comprising an acid solution is flow connected to each of the desorption sub-stages 1D, 2D and 3D which supplies acid to the desorption sub-stages 1D, 2D and 3D to maintain each under acid conditions such that contact the solution 14 contacts the lithium rich ion exchange material which results in lithium and impurities being desorbed from ion exchange material, thereby providing slurry 29 including a lithium eluate and an at least partially regenerated ion exchange material. As described herein, the impurities may include Group II metals including one or more of Ca (Calcium), Sr (Strontium) and Ba (Barium). The desorption stage 12 is configured so that sulphate ions in the solution react with the impurities desorbed from the ion exchange material to form sulphate precipitates in the desorption stage 12. For instance, the sulphate ion may be provided by the sulphuric acid of the acid source. In addition, the P0512WOplant 11 may include an alkali sulphate source, not shown in Figure 2, that supplies alkali sulphate separately to each desorption stage 1D, 2D and 3D. As mentioned above, each desorption sub-stage 1D, 2D and 3D may be a moving bed such as fluidised bed, or an elutriating bed as described and shown in Figure 3.

[0116] The plant 10 also includes a washing stage 16 which receives the regenerated ion exchange from Desorption stage 3D which is the last desorption stage. The washing stage 16 has a water inlet for washing water, a solids inlet for supplying the ion exchange material, and a water outlet for discharging first spent watering water and a solids outlet for discharging washed ion exchange material. The washing stage 16 may be operated as continuous counter current operation or a semi batch operation in which wash water flows through the washing stage, and ion exchange material is discharged intermittently.

[0117] The plant 10 also includes a first reverse osmosis treatment stage 18 having an inlet that receives the first spent wash water, and a brine outlet that discharges brine 19. The brine outlet is connected to Desorption sub-stage 3D, being the last the desorption sub-stages, in which the brine 19 is used to supply all or part of the solution 14 that contacts the lithium rich ion exchange material in the desorption stage 12. The first reverse osmosis treatment stage 18 also includes a permeate outlet that discharges a permeate 20 which can reused to provide part of the washing water.

[0118] The plant 10 includes a first pH sensor, not illustrated, that senses the acidity of the Desorption sub-stages 1D, 2D and 3D, and a first controller, not illustrated, that controls the supply of an acidic solution from the acid sources to the Desorption sub-stages 1D, 2D and 3D, based on an output signal of the pH sensor. The output signal of the first pH sensor is received by the first controller and may be a digital or analogue signal. The controller can control the flow rate and / or volume of the acid 22 supplied to the or each desorption stages 1D, 2D and 3D from the acid source 50.

[0119] Although not shown in Figure 1, the plant 11 may also include an alkali sulphate source containing a sulphate solution such as one or more of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4), potassium sulphate K2SO4 and ammonium sulphate (NH4)The plant 10 includes a conduit for supplying the alkali sulphate solution to the desorption stages 1D, 2D and 3D, to supplement sulphate ions that form precipitates in the desorption stages 1D, 2D and 3D, with the impurities.

[0120] The desorption sub-stages 1D, 2D and 3D, include an outlet that discharges a slurry 23, 26 and 29 including the ion exchange material, sulphate precipitates and the solution 15 including lithium eluate. Each desorption sub-stages 1D, 2D and 3D, has a stage separator 24, 27 and 30 that separates the ion exchange material from the sulphate precipitates and the solution 14, with the solution 14 including sulphate precipitates and the lithium eluate. The stage separators 24, 27 and 30 includes a screening device having openings that are sized to retain the ion exchange material. For example, the openings may be sized to retain ion exchange material equal to greater than 200µm in size, thereby allowing the solution including sulphate precipitates and lithium eluate to pass through the stage separators 24, 27 and 30 and be supplied to previous desorption sub-stage in the direction of flow of the ion exchange material.

[0121] The plant 11 also includes a precipitates separator 31 that is configured to receive the solution 14 including sulphate precipitates and the lithium eluate that is discharged from the stage separator 30 P0512WOof the first desorption sub-stage arranged first in the movement direction of the ion exchange material, namely the Desorption sub-stage 1D. The precipitates separator 30 separates the sulphate precipitates from the solution 14 to produce a lithium product stream 32 and solid product containing the precipitated impurities 33. The precipitates separator 31 may be any suitable device such as a centrifuge, a filter / screening device, or a gravitational separator such as a settling pond, an overflow weir.

[0122] With reference to Figure 2, the plant 11 includes an adsorption stage 35 comprising adsorption sub-stages 1A, 2A and 3A, that has a feed inlet that receives a lithium feed liquid containing dissolved lithium and the impurities, and a solid inlet that receives the regenerated ion exchange material from the washing stage 16 shown in Figure 1. The adsorption sub-stages 1A, 2A and 3A, are configured to be operated under controlled pH conditions so that the ion exchange material sorbs lithium and at least a portion of the impurities, including Ca (Calcium), Sr (Strontium), and Ba (Barium) from the lithium feed liquid to provide the lithium enriched ion exchange material. As can be seen the adsorption sub-stage includes three adsorption sub-stages in which the lithium feed liquid is supplied to a first adsorption sub-stage, namely Adsorption Stage 1A, and a partially depleted lithium feed liquid is supplied from the subsequent adsorption sub-stage, namely Adsorption sub-stage 2A, and then to a final adsorption sub-stage, namely Adsorption sub-stage 3A. The ion exchange material is conveyed in counter current between the sub-stages 1A, 2A and 3A from the final adsorption sub-stage 3D to the first adsorption sub-stage 1D. Each of the adsorption sub-stages 1A, 2A and 3A can be arranged as a moving bed.

[0123] The plant 11 includes a base / alkali source, not illustrated, that supplies a base / alkali to each of the adsorption sub-stages 1A, 2A and 3A. Although not shown in Figure 2, the plant 11 includes a second pH sensor that senses the pH in each of the adsorption sub-stages 1A, 2A and 3A and a second controller that controls the supply of the base / alkali based an output signal of the second pH sensor received by the second controller.

[0124] Each of the adsorption sub-stages 1A, 2A and 3A is associated with, or includes a material separator 40, 41 and 42 for separating the ion exchange material and the partially depleted lithium feed liquid. As can be seen in Figure 2, the material separator 40 receives intermediate slurry 37 including the final loaded lithium rich ion exchange material 28, the material separator 41 receives the intermediate slurry 37 including the lithium stream 32, and the material separator 42 receives the final slurry 39 including partially loaded ion exchange material 38 and the discharge liquid 43. The plant also includes a second wash step 44 to remove lithium feed liquid from the lithium rich ion exchange material 28 which provides a second spent washing water 46 and rinsed ion exchange material that can then be fed to the desorption sub-stage 1A.

[0125] The plant 11 also includes a second reverse osmosis treatment stage 51 having an inlet that receives the second spent wash water 46, a concentrate outlet that discharges a concentrated RO brine 47, and a permeate outlet. The concentrate outlet is connected to a line supplying the lithium feed liquid so the concentrated RO brine can be added to the lithium feed liquid. The permeate outlet is connected to a line that the washing water so a permeate 48 can be added to the second spent wash water.

[0126] Figure 3 is a schematic illustration of a moving bed in the form of an elutriating bed which combines gravitational settling and air agitation. The elutriating bed may be used in either one, or P0512WOboth of, the adsorption step 35 and the desorption step 12. As can be seen, both ion exchange material and a liquid enter the top of the elutriating bed, and ion exchange material exits at the bottom of the bed, and lithium eluate and precipitates (if present) can be discharged from the top of the bed. A fluidising stream, such as air, is blown into the bed toward the bottom third or quarter of the bed to assist in fluidising the contents, and simultaneous separation of ion exchange material from the liquid generally occurs below an inlet of the fluidising stream.

[0127] In the case of the desorption step 12, the liquid entering the top of the elutriating bed shown in Figure 3 will be either the RO brine for the Desorption stage 3D, or the lithium eluate for Desorption sub-stages 1D and 2D. Partially regenerated ion exchange material 13 will be discharged from the bottom of Desorption sub-stages 1D and 2D, and regenerated ion exchange material 15 will be discharged from the bottom of Desorption sub-stage 3D. The acid solution may be added with the fluidising stream or at some other inlet, including with the liquid stream.

[0128] In the case of the adsorption step 35, the feed lithium liquid or a partially depleted form thereof, and the ion exchange material, are fed to the top of the elutriating bed. A partially loaded ion exchange material is discharged from the bottom of the bed of, for example, Adsorption sub-stage 3A, and a loaded ion exchange material is discharged from the bottom of bed, for example, Adsorption sub-stage 1A. The alkaline solution may be added with the fluidising stream or at some other inlet, including with the liquid stream.

[0129] A possible advantage of the elutriating bed is that when used for the desorption step, it can avoid the need for dedicated separation steps of the ion exchange material and the lithium eluate discharged from the desorption step. Similarly, when used for the adsorption step, it can avoid the need for dedicated separation steps of the ion exchange material and the feed lithium liquid and a precipitate (if present). EXAMPLE

[0130] A series of trials have been conducted demonstrating implementation of the process and plant. The trials included loading an ion-exchange material in an adsorption step with lithium feed liquor including impurities, and a desorption step in which lithium and impurities were desorbed to provide a lithium eluate and precipitates including of sulphate impurities. Adsorption

[0131] The trials included forming equilibrium adsorption isotherms in multiple batch reactors in which a Li-selective adsorbent was contacted with a Lithium feed liquor to produce a barren lithium liquor and a loaded absorbent material. The sorbent was Mn-based sorbent provided by XtraLit, a commercial supplier of ion exchange materials based in Rehovot, Israel. Table 1 below details the elemental composition of the Lithium feed liquor. Table 1: Composition of Li-containing brine (mg / L)P0512WO

[0132] Each adsorption stage was performed for a minimum of 6 hours in a stirred jacketed reactor connected to a water bath for temperature control. Each batch reactor had a fixed amount of Li- barren sorbent which was stirred with a fixed volume of lithium feed liquor at constant pH until approximate equilibrium was established. The sorbent was separated from the liquor, and a sample of the liquor was retained. A fresh portion of Li-barren sorbent was added to the partially Li-depleted liquor, and the process was repeated again for another three or four times, denoted by the letters A to E in Tables 2a, 2b and 2c below.

[0133] A pH probe was immersed into the Lithium feed liquor and connected to the automatic pH controller to maintain pH at the desired value of 6.6 ± 0.1. Isotherms were maintained at temperatures of 50°C and 70°C using sodium hydroxide for pH control, and another isotherm using lime for pH control at 70°C. Adsorption kinetics were measured at 70°C and pH 6.6 ± 0.1.

[0134] Table 2a, 2b and 2c comprise data on Lithium concentrations in the barren liquor and the loaded onto the adsorbent after each adsorption stage for 50 or 70°C isotherms using with NaOH or lime pH control as shown. Table 2a: Adsorption isotherm data Table 3b: Adsorption isotherm dataTable 4c: Adsorption isotherm data

[0135] Table 3 below shows the loadings of Lithium adsorbed in the sorbent as a function of time and P0512WOin turn the percentage of loaded Li for an equilibrium loading. Each loading was measured after stirring a portion of the sorbent with lithium feed liquor for the time periods shown at 70ºC. Since a high liquor-to-sorbent ratio was used, pH control was not required, and acidity remained constant at approximately pH 6.6. Table 5: Adsorption kinetics data (Li)

[0136] Table 4 below shows the loadings of Calcium (Ca), Strontium (Sr), Potassium (K), Magnesium (Mg) and Barium (Ba) as a function of. Each loading was measured after stirring a portion of the sorbent with lithium feed liquor for the time periods shown at 70ºC. Since a high liquor-to-sorbent ratio was used, pH control was not required, and acidity remained constant at approximately pH 6.6. Table 4: Adsorption kinetics data (for precipitating metals, Ca, Sr and Ba, and non-precipitating metals K and Mg)Desorption

[0137] Lithium rich sorbent was prepared as described and washed to remove entrained feed liquor. The desorption step included mixing the washed lithium rich sorbent with a fixed amount of water in rotatable vessel, and then concentrated sulfuric acid was slowly added drop-wise to achieve a free acid concentration of 0.015 g / L H+(pH 1.5) while stirring. During acid addition, a white precipitate (alkaline earth sulphates) formed. Once the free acid concentration had stabilised, the slurry was mixed by rolling for 15 hours. A solution including Lithium eluate was recovered, which was been denoted trial A, see description in Table 6, and was contacted with a lithium rich sorbent, denoted as trial B, and the same process was repeated again twice more, and denoted as trials C and D, to generate an elution isotherm. In addition, partially depleted Li-loaded sorbent from trials A, B C and D was added to a fixed amount of water and again concentrated sulfuric acid was slowly added drop- wise to achieve a free acid concentration of 0.015 g / L H+(pH 1.5) while stirring. Precipitates including alkaline earth sulphates were again formed. Once the free acid concentration had stabilized, the slurry P0512WOwas mixed by rolling for 15 hours.

[0138] The separation of the sorbent from the precipitates was carried out based on size, and a similarly, separation of the precipitates from the lithium eluate was carried out by filtration. Based on the elution isotherm, an eluate containing over 8 g / L lithium was produced, which reduces the flow for downstream treatment. Table 5 shows that the concentrations of Ca, Sr and Ba in the lithium eluate remained low, as the solubility of these ions was limited by the presence of. Table 5: Elution isotherm dataTable 6. – details of tests for elution isotherm data:

[0139] Table 7 shows the mass balances based on eluate solution and sorbent after trials A, B C and D. As can be seen, the recovery to eluate for Ca, Sr and Ba are low since these elements have poorly soluble sulfate salts, the unaccounted mass for Ca, Sr and Ba in the Lithium eluate was assumed to present in the precipitates. Conversely, the recovery to eluate based on Lithium eluate and sorbent for Li, Mg and K are close to 100%, since the sulfate salts of these elements are soluble. P0512WOTable 7: Mass balance data for elution (metal in sorbent and liquor out vs metal in sorbent and liquor in)

[0140] These results of the trials show that the desorption of Li is efficient, and that co-loaded Ca, Sr and Ba are eluted from the sorbent and precipitated as precipitates than can be separated from the ion exchange material and the lithium eluate solution.

[0141] The effect of free acid on desorption was also tested. Portions of a loaded sorbent (generated from the lithium feed liquor were contacted with different amounts of sulphuric acid, resulting in different final free acid concentrations. Table 8 below shows the metals, Li, Ca, K Mg and Na are desorbed across the range of pH 2-4, and that desorption is more efficient at lower pH (higher free acid). P0512WOTable 8: Effect of free acid on desorption

[0142] Finally, desorption kinetics were measured by contacting portions of lithium rich sorbent with a volumetric excess of sulphuric acid solution (0.015 g / L free H+) for various periods of time (up to 24 hours) at ambient temperature (approximately 20°C). At the end of each contact, the sorbent was separated from the solution, washed, and stripped to account for residual Li concentrations which are summarized in Table 9 below. More than 90% of equilibrium elution was achieved within one hour, and the sorbent was fully equilibrated with the lithium eluate solution in under 5 hours. On average, a residual lithium concentration of ~1,500 mg / kg was achieved, corresponding to ~90% stripping efficiency. Table 9: Elution kinetics data (N / A = not analysed, ND = not detected)

[0143] While the above detailed description has shown, described, and pointed out novel features as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices or methods illustrated can be made without departing from the spirit of the disclosure. As will be recognized, certain embodiments of the inventions described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others. P0512WOReference numeralsP0512WO

Claims

CLAIMS 1. A process of recovering lithium, the process includes a desorption step for recovering lithium from a lithium enriched ion exchange material that is co-loaded with impurities, in which the desorption step includes: contacting the lithium enriched ion exchange material that is co-loaded with impurities with a solution under acid conditions to at least partially desorb lithium and, at least partially desorb impurities from the ion exchange material to provide a lithium eluate and a regenerated ion exchange material; wherein the desorption solution includes sulphate (ions) such that the desorption step includes at least a portion of the impurities desorbed from the ion exchange material precipitating as sulphate precipitates, wherein the impurities include Group II metals including one or more of Ca (Calcium), Sr (Strontium) and Ba (Barium).

2. The process according to claim 1, wherein the impurities include Group II metals including at least two of Ca (Calcium), Sr (Strontium) and Ba (Barium).

3. The process according to claim 1, wherein the impurities include Group II metals including all three of Ca (Calcium), Sr (Strontium) and Ba (Barium).

4. The process accruing to claim 1, wherein the sulphate precipitates includes only trace amounts of Be (Beryllium) and Mg (Magnesium).

5. The process according to any one of the preceding claims, wherein the desorption step is carried out in one or more moving bed to reduce fouling and / or blockages.

6. The process according to any one of the preceding claims, wherein precipitation of the sulphate precipitates occurs simultaneously (or concurrently) during the desorption step.

7. The process according to any one of the preceding claims, wherein the process includes discharging the lithium eluate and the sulphate precipitates in a single stream from the desorption step.

8. The process according to any one of the preceding claims, wherein the process includes discharging the ion exchange material, the lithium eluate and the sulphate precipitates in a single stream from the desorption step.

9. The process according to the preceding claim, wherein the process includes a separating step of separating the ion exchange material from the lithium eluate and the sulphate precipitates.

10. The process according to any one of the preceding claims, wherein the ion exchange material is larger than the sulphate precipitates, and preferably the ion exchange material has a particle size of equal to or greater than 200μm, and preferably the ion exchange material has a particle size from 200 to 2000μm, and preferably the ion exchange material has a particle size from 500 to 2000μm.

11. The process according to any one of the preceding claims, wherein the sulphate precipitates are fine particles that are less than 200μm in size. P0512WO12. The process according to any one of the preceding claims, wherein the process includes washing the regenerated ion exchange material with washing water to form a spent washing water, and using at least a portion of spent washing water to provide the solution in the desorption step.

13. The process according to claim 12, wherein the process includes a treatment step of treating the spent washing water to form a brine and a cleansed washing water, in which at least a portion of the brine forms the desorption solution fed to the desorption step.

14. The process according to the preceding claims, wherein the treatment step is a reverse osmosis treatment in which permeate of the treatment provides the cleansed washing water, and a concentrate provides the brine.

15. The process according to any one of the preceding claims, wherein the process includes controlling the pH during the desorption step so as to provide free H+ions to facilitate desorption of lithium and the impurities from the exchange material.

16. The process according to claim 12, wherein controlling the pH includes adding sulphuric acid to the desorption step so that the desorption step is carried out under conditions with 0.03 to 0.071 g / L free H+ions.

17. The process according to claim 16, wherein the process includes controlling the flow rate and / or volume of an acid solution fed to the desorption step, and thereby reduce dilution of the lithium eluate discharged from the desorption step 18. The process according to any one of the preceding claims, wherein the process includes adding an alkali sulphate to a desorption step to provide sulphate anions for forming the sulphate precipitates.

19. The process according to claim 18, wherein adding alkali sulphate to the desorption step includes adding a solution including any one or more of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4), potassium sulphate K2SO4and ammonium sulphate (NH4)2SO4.

20. The process according to any one of the preceding claims, wherein the process includes controlling the flow rate of the solution fed to the desorption step, and thereby reduce dilution of the lithium eluate discharged from the desorption step.

21. The process according to any one of the preceding claims, wherein the process includes separating the lithium eluate from the sulphate precipitates to produce a lithium product solution and a solid product containing impurities.

22. The process according to any one of the preceding claims, wherein the desorption step is carried out in multiple sub-stages in which the free H+conditions of at least two sub-stages is different from the free H+conditions of another stage.

23. The process according to any one of the preceding claims, wherein the desorption step is carried out in multiple desorption sub-stages, where the lithium enriched ion exchange material is supplied to a first sub-stage, hereinafter referred to as the previous sub-stage, and at least partially depleted ion exchange material is discharged from the previous sub-stage and supplied to at least one subsequent sub-stage defining a direction of movement of the ion exchange material between the P0512WOdesorption sub-stages, and the solution including the lithium eluate is conveyed in counter current from the at least one subsequent sub-stage to the previous sub-stage.

24. The process according to claim 23, wherein free H+in the previous sub-stage is lower than the free H+conditions in the at least one subsequent sub-stage.

25. The process according to claim 23 or 24, wherein the process includes discharging a slurry from the at least one subsequent sub-stage, the slurry including the ion exchange material, the sulphate precipitates and the lithium eluate, and the process includes separating the ion exchange material from the lithium eluate and the sulphate precipitates, and supplying the lithium eluate and the sulphate precipitate to the previous sub-stage to provide the solution.

26. The process according to any one claims 23 to 25, wherein the process includes discharging the slurry from the first sub-stage, the slurry including the ion exchange material, the sulphate precipitates and the lithium eluate, and the process includes separating the ion exchange material from the lithium eluate and the sulphate precipitates, and the process includes another separating step in which the lithium eluate and the sulphate precipitates are separated into a lithium product solution and a solid product containing the impurities.

27. The process according to any one of the preceding claims, wherein the desorption step is carried out at ambient temperature, and has a residence time in the range of 1 to 10 hours.

28. The process according to any one of the preceding claims, wherein the process includes an adsorption step in which a lithium feed liquid containing dissolved lithium and the impurities are contacted with the regenerated ion exchange material and under controlled pH conditions to sorb lithium and sorb at least a portion of the impurities include Ca (Calcium), Sr (Strontium), and Ba (Barium) from the lithium feed liquid to provide the lithium enriched ion exchange material.

29. The process according to claim 28, wherein a depleted lithium liquid can be discharged from the adsorption step, and preferably, the depleted lithium liquid can be returned to the origin of the lithium feed liquid.

30. The process according to claim 28 or 29, wherein the process includes controlling the pH conditions of the adsorption step to a pH in the range of 5 to 9, and preferably to a pH in the range from 7 to 9.

31. The process according to any one of claims 28 to 30, wherein the adsorption step includes adding a base / alkali to control the pH, preferably the base / alkali includes calcium hydroxide (Ca(OH)2), and / or sodium hydroxide (NaOH).

32. The process according to any one of claims 28 to 31, wherein the adsorption step is carried out in multiple adsorption sub-stages in which the lithium feed liquid is supplied to a first or preceding adsorption sub-stage and a (partially) depleted lithium feed liquid is supplied from the preceding adsorption sub-stage to a subsequent adsorption sub-stage, and the ion exchange material is conveyed in counter current between the sub-stages from the subsequent adsorption sub-stage to the preceding adsorption sub-stage. P0512WO33. The process according to claim 32, wherein the process includes a separating step in which the ion exchange material and the partially depleted lithium feed liquid are separated between the adsorption sub-stages.

34. The process according to any one of claims 28 to 33, wherein each adsorption sub-stage is a moving bed, such as fluidised bed or agitated bed.

35. The process according to any one of claims 28 to 34, wherein the process includes washing the lithium enriched ion exchange material with wash water to remove lithium feed liquid from the ion exchange material to provide a second spent washing water.

36. The process according to claim 35, wherein the process includes adding at least a portion of the second spent washing water to the feed liquid.

37. The process according to claim 36, wherein the process includes adding all of the second spent washing water to the feed water.

38. The process according to claims 36 or 37, wherein the process includes a second step of treating the second spent washing water to provide a concentrated brine which can be added to the feed liquid, and a cleansed washing water that can be used as the washing water with optional makeup wash water.

39. The process according to claim 38, wherein the step of treating the spent washing water includes a reverse osmosis treatment in which a permeate of the treatment provides the cleansed washing water and concentrated RO brine can be added to the lithium feed liquid.

40. The process according to any one of claims 28 to 39, wherein the adsorption step is carried out at a temperature in the range of 10 to 80ºC, and even more suitably in the range of 50 to 70ºC.

41. The process according to any one of the preceding claims, wherein the lithium rich ion exchange material has from 2,000 to 17,000 mg / kg of Lithium sorbed onto the ion exchange material.

42. A plant in which the process of any one of the preceding claims is carried out.

43. A plant for recovering lithium, the plant includes at least one desorption stage for recovering lithium from a lithium enriched ion exchange material that is co-loaded with impurities, the desorption stage being configured to receive the lithium enriched ion exchange material that is co-loaded with impurities and receive a solution that contacts the lithium enriched ion exchange material under acidic conditions to at least partially desorb lithium to provide a lithium eluate and at least partially desorb impurities from the ion exchange material to form an at least partially regenerated ion exchange material, wherein the impurities include Group II metals including one or more of Ca (Calcium), Sr (Strontium) and Ba (Barium), and the desorption stage is configured so that sulphate ions in the solution react with the impurities desorbed from the ion exchange material to form sulphate precipitates in the desorption stage.

44. The plant according to claim 43, wherein the desorption stage is configured as a moving bed in which the ion exchange material and the sulphate precipitates are fluidised.

45. The plant according to claim 43 or 44, wherein the plant includes a washing stage in which the at least partially regenerated ion exchange material is washed with washing water, and has an ion P0512WOexchange material outlet from which regenerated ion exchange material is discharged, and a water outlet from which a first spent wash water is discharged.

46. The plant according to any one of claims 43 to 45, wherein the plant includes a first reverse osmosis treatment stage having an inlet that receives the first spent wash water, and a brine outlet that discharges brine, the brine outlet being connected to the desorption stage so the brine can be used as the solution that contacts the lithium rich ion exchange material in the desorption stage, and a permeate outlet that discharges a permeate.

47. The plant according to any one of claims 43 to 46, wherein the plant includes a first pH sensor that senses the acidity of the desorption stage, an acid source including an acidic solution, and a first controller that controls the supply of the acidic solution to the desorption stage based on an output signal of the pH sensor that is received by the first controller.

48. The plant according to claim 47, wherein the controller includes controlling the flow rate and / or volume of the acid solution fed to the desorption stage.

49. The plant according to any one of claims 43 to 48, wherein the plant includes an alkali sulphate source having sulphate solution including one or more of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4), potassium sulphate K2SO4and ammonium sulphate (NH4)2SO4, and the plant includes a conduit for supplying the sulphate solution to the desorption stage.

50. The plant according to any one of claims 43 to 49, wherein the plant includes at least two of the desorption sub-stages, in which a first desorption stage, hereinafter referred as the previous sub- stage, is configured to receive the lithium enriched ion exchange material, and at least partially depleted ion exchange material is discharged from the previous sub-stage and supplied to at least one subsequent sub-stage defining a direction of movement of the ion exchange material between the previous sub-stage to the subsequent sub-stage, and the solution is conveyed in counter current from the at least one subsequent sub-stage to the respective previous sub-stage.

51. The plant according to any one of claims 43 to 50, wherein the or each desorption sub-stage includes an outlet that discharges a slurry including the ion exchange material, sulphate precipitates and the solution including lithium eluate, and the or each desorption sub-stage has a stage separator that separates the ion exchange material from the sulphate precipitates and the solution.

52. The plant according to claim 51, wherein the stage separator is configured to separate the ion exchange material from the sulphate precipitates and the solution by holding the ion exchange material on a screening device, and the solution and the precipitates pass through screening device.

53. The plant according to claim 52, wherein the screening device has openings that are sized for holding the ion exchange material that is equal to greater than 200µm in size.

54. The plant according to any one of claims 51 to 53 when appended to claim 45 or 46, wherein the washing stage is configured to receive the ion exchange material discharged from the stage separator of the subsequent sub-stage that is arranged last in the movement direction of the ion exchange material.

55. The plant according to any one of claims 51 to 54, wherein the plant includes a precipitates separator that is configured to receive the sulphate precipitates and the solution including lithium P0512WOeluate from the stage separator of the previous sub-stage arranged first in the movement direction of the ion exchange material, the precipitates separator separating the precipitates from the solution to produce a lithium product solution and solid product containing the impurities.

56. The plant according to any one of claims 43 to 55, wherein the plant includes an adsorption stage that has a feed inlet that receives a lithium feed liquid containing dissolved lithium and the impurities, and the regenerated ion exchange material, and the adsorption stage is configured to be operated under controlled pH conditions so that the ion exchange material sorbs lithium and at least a portion of the impurities, including Ca (Calcium), Sr (Strontium), and Ba (Barium) from the lithium feed liquid to provide the lithium enriched ion exchange material.

57. The plant according to claim 56, wherein the plant includes a base / alkali source that supplies a base / alkali to the adsorption stage.

58. The plant according to claim 57, wherein the plant includes a second pH sensor that senses the pH in the adsorption stage and a second controller that controls the supply of the base / alkali based an output signal of the second pH sensor received by the second controller.

59. The plant according to any one of claims 56 to 58, wherein adsorption stage includes at least two adsorption sub-stages in which the lithium feed liquid is supplied to a first or preceding adsorption sub-stage and a (partially) depleted lithium feed liquid is supplied from the preceding adsorption sub- stage to a subsequent adsorption sub-stage, and the ion exchange material is conveyed in counter current between the sub-stages from the subsequent adsorption sub-stage to the preceding adsorption sub-stage.

60. The plant according to any one of claims 56 to 59, wherein the or each adsorption sub-stage is a moving bed.

61. The plant according to any one of claims 56 to 60, wherein the or each adsorption sub-stage includes a material separator for separating the ion exchange material and the partially depleted lithium feed liquid.

62. The plant according to claim 61 when appended to claims 59, wherein the material separator is configured to discharge ion exchange material and supply the ion exchange material to the subsequent adsorption sub-stage (in the direction of flow of the ion exchange material), and is configured to supply the partially depleted lithium feed liquid to the preceding adsorption sub-stage (in the direction of flow of the ion exchange material).

63. The plant according to any one of claims 56 to 62, wherein the plant includes a second washing stage that is configured to wash the lithium enriched ion exchange material discharged from the adsorption stage with washing water to remove lithium feed liquid from the ion exchange material which provides a second spent washing water.

64. The plant according to claim 63, wherein the plant includes a second reverse osmosis treatment stage having an inlet that receives the second spent wash water, a concentrate outlet that discharges a concentrated RO brine, the concentrate outlet being connected to a line supplying the lithium feed liquid so the concentrated RO brine can be added to the lithium feed liquid, and a permeate outlet. P0512WO

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