Spodumene enrichment for lithium recovery

Abstract

Provided herein is a method of recovering lithium concentrate from spodumene-containing ore. The ore is crushed to obtain a fine fraction and a coarse fraction. The coarse fraction is calcined at a temperature of about 950 to about 1100 DEG C to obtain a calcined coarse fraction comprising spodumene particles having a beta crystal structure. The calcined coarse fraction is selectively screened to separate spodumene particles to produce screened spodumene particles. The screened spodumene particles are magnetically separated to enrich spodumene particles and separate out non-magnetic contaminants to recover lithium concentrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 479,045, filed on January 9, 2023, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates generally to the field of lithium recovery from spodumene ores. Background Art

[0004] As global demand for lithium continues to grow, pressure is growing to extract lithium from ores such as spodumene. Methods for recovering lithium from spodumene typically involve enriching the spodumene through flotation or a combination of flotation and heavy media separation. Following the enrichment step, the spodumene concentrate is typically calcined to allow lithium extraction using conventional hydrometallurgical processes, such as sulfuric acid leaching.

[0005] Flotation methods require many steps to achieve satisfactory metallurgical properties: crushing, ore sorting, fine grinding, fines removal, slurry conditioning, mica removal (if necessary), spodumene flotation (multiple steps), magnetic separation, filtration, and calcination. Given its complexity and the number of steps required, lithium recoveries in this method are typically less than 80%. In addition, the use of chemical reagents complicates the handling of the residue. Dense media separation is another spodumene enrichment method, but it is not suitable for all spodumene deposits, and the recovery of this method is typically less than 50%.

[0006] It was recently discovered that calcination and selective screening of β-spodumene significantly improves lithium yields while limiting or eliminating flotation and its associated steps (WO2022 / 204787).

[0007] However, there is a need to further improve the recovery yield. Summary of the Invention

[0008] In one aspect, a method for recovering lithium concentrate from a spodumene-containing ore is provided, the method comprising: crushing the ore to obtain a fine fraction and a coarse fraction; calcining the coarse fraction, preferably at a temperature of about 950 to about 1100° C., to obtain a calcined coarse fraction comprising spodumene particles having a β crystal structure; selectively screening the calcined coarse fraction to separate the spodumene particles to produce screened spodumene particles; and / or magnetically separating the screened spodumene particles to enrich the spodumene particles and separate non-magnetic contaminants to obtain lithium concentrate.

[0009] In some embodiments, the lithium concentrate comprises at least about 3% Li2O.

[0010] In some embodiments, selective screening includes vibratory screening, air flow sorting, cyclone classification, or any other means of size separation.

[0011] In some embodiments, comminuting comprises mechanical grinding and / or milling.

[0012] In some embodiments, the coarse fraction comprises particles having a size of 850 μm or greater.

[0013] In some embodiments, the coarse fraction comprises particles having a size of 500 μm or greater.

[0014] In some embodiments, the particles of the coarse fraction have a size of up to 15 mm.

[0015] In some embodiments, the spodumene particles have a size of at least about 300 μm.

[0016] In some embodiments, the method further comprises obtaining a lithium salt from the lithium concentrate.

[0017] In some embodiments, the lithium salt is LiOH, Li2O, and / or Li2CO3.

[0018] In some embodiments, magnetic separation is performed using magnetized rollers or drums.

[0019] In some embodiments, a rare earth roller magnetic separator is used in the magnetic separation.

[0020] In some embodiments, a multi-channel magnetic separator is used in the magnetic separation.

[0021] In some embodiments, the multi-channel magnetic separator is a three-channel magnetic separator.

[0022] In another embodiment, the methods described herein further comprise the step of determining the degree of embrittlement of the spodumene particles in the calcined coarse fraction.

[0023] In one embodiment, the degree of embrittlement is determined by microscopic observation, macroscopic visual inspection, or size distribution analysis.

[0024] In another embodiment, the method described herein further comprises grinding and / or milling the spodumene particles if the embrittlement level of the spodumene particles is below a predetermined threshold.

[0025] In one embodiment, the threshold value is that the size of the spodumene particles is about 4 times smaller, about 4.25 times smaller, 4.5 times smaller, or preferably 5 times smaller than the mineral particles.

[0026] In another embodiment, the method described herein further comprises the step of autoclaving the lithium concentrate to produce a slurry.

[0027] In one embodiment, the salt additive and / or the aqueous phase are added during heating of the autoclave.

[0028] In another embodiment, the methods described herein further comprise biocarbonization of the slurry to produce a solution containing LiHCO 3 .

[0029] In one embodiment, biocarbonization removes impurities.

[0030] In another embodiment, the process described herein produces a lithium concentrate having an impurity content of less than 0.5%.

[0031] In one embodiment, calcining the coarse fraction transforms the crystal structure of the spodumene particles from an alpha crystal structure to a beta crystal structure. Calcining the coarse fraction can be performed using natural gas, propane, heavy oil, biomass, and / or electricity, using, for example, a directly heated rotary kiln, an indirectly heated rotary kiln, and / or a fluidized bed.

[0032] In one aspect, a lithium ion battery is provided, comprising a lithium salt prepared by the method of the present disclosure.

[0033] After reading this disclosure, those skilled in the art will recognize many additional features and combinations thereof relating to the present improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A flowchart showing a method according to one embodiment of the present disclosure is provided. DETAILED DESCRIPTION

[0035] The method of the present disclosure seeks to improve the yield of lithium recovery from ore, concentrate or waste by adding a magnetic separation step after calcination (i.e., magnetic separation of β-spodumene). Magnetic separation is conventionally performed upstream of calcination (when the spodumene is α-spodumene) to remove iron-containing gangue impurities (minerals) associated with the spodumene. For example, a high-intensity magnetic separator can be used to remove iron-containing impurities. However, it was unexpectedly found that β-spodumene can be further purified as a magnetic material to remove contaminants such as quartz and other non-magnetic gangue minerals. Therefore, this method is contrary to the traditional magnetic separation of α-spodumene performed upstream, where α-spodumene is a non-magnetic mineral species and iron-rich contaminants with stronger magnetic forces are removed.

[0036] refer to Figure 1, a method for preparing lithium concentrate 100 is provided. First, ore obtained from a mine is crushed into a fine particle fraction and a coarse particle fraction 102. Alternatively, a lithium-containing concentrate or waste material may be provided. The waste material may be crushed as needed. Thus, a crushed product may be obtained after completion of step 102. Typically, the ore contains spodumene (and other minerals). The ore may be a run of ore (ROM) containing spodumene or a spodumene concentrate. Spodumene contains most of the lithium present in the ore. In some embodiments, at least 95% of the lithium in the ore is contained in spodumene. The ore may be crushed to have a size of less than about 15 mm. Crushing the ROM may dissociate spodumene particles that may be associated with other minerals. Thus, in some embodiments, the method includes crushing the ROM ore to obtain crushed ore particles having a size of less than 15 mm and, in some embodiments, less than 6 mm. The crushed ore yields a fine particle fraction and a coarse particle fraction. The spodumene ore fed to the method may have any Li2O grade and may be a run of ore, pre-concentrated ore, or concentrating ore from any process. Examples of pre-concentration / concentration methods may include ore sorting, heavy medium separation, flotation, magnetic separation, and / or others. As explained herein, in some embodiments, when calcined ore (rather than calcined concentrate) is processed, the present method does not include flotation and heavy medium separation. In this case, flotation and heavy medium separation are not required, so they only increase cost and complexity without significantly affecting the yield of lithium that can be obtained. However, heavy medium separation may be used before calcining the coarse fraction, which is only used to reduce the calcination mass / reduce the energy demand for calcination, but this is only optional. In some embodiments, flotation may optionally be applied to the fine fraction. In some embodiments, heavy medium separation is applied to the coarse fraction, and flotation is applied to the fine fraction. In some embodiments, when the raw material is a concentrate, heavy medium separation and flotation may be performed. In another embodiment, the fine fraction may also be calcined. The lithium contained in the calcined product may be recovered by screening and a magnetic separator.

[0037] In other embodiments, the method includes sorting the crushed product to obtain a fine particle fraction and a coarse particle fraction. This can be achieved by size separation methods (for example, using a screen of appropriate size or air flow sorting). In one embodiment, the term "fine particle fraction" as used herein refers to a fraction comprising particles having a size less than about 850 μm, less than about 700 μm, less than about 600 μm, less than about 500 μm, less than about 400 μm or less than about 300 μm. The minimum size of the fine particle fraction can be, for example, 45 μm. The term "coarse particle fraction" as used herein refers to a fraction comprising particles having a size greater than that of the fine particle fraction. For example, the coarse particle fraction comprises particles having a size of at least about 300 μm, at least about 400 μm, at least about 500 μm, at least about 600 μm, at least about 700 μm or at least about 850 μm or larger.

[0038] Separating the fine and coarse particles into their respective fine and coarse fractions prior to calcination can improve the gangue / spodumene separation efficiency of the coarse particles. This can result in higher spodumene enrichment (higher concentrate grade).

[0039] The coarse fraction from the crushed ore is then subjected to a calcination step 104. In some embodiments, the coarse fraction is provided "after crushing" and no other separation steps are performed on the coarse fraction. For example, no flotation or heavy media separation is performed on the coarse fraction between crushing and calcination. On the other hand, the fine fraction can be subjected to flotation and / or any other suitable separation method to extract lithium therefrom. In the present disclosure, it is the coarse fraction that is of interest. One object of the present method is to reduce the amount of material that is subjected to flotation and / or heavy media separation (e.g., by up to 90%) by not including a coarse fraction (instead, the coarse fraction is subjected to the separation methods described herein). Significant cost reductions can thus be achieved, as flotation and heavy media separation require many steps and equipment.

[0040] The calcining 104 is performed to change the crystal structure of the spodumene particles, which then allows for selective screening 106. Spodumene naturally occurs in its relatively stable alpha crystal structure (i.e., alpha-spodumene) (and in some embodiments is resistant to chemical degradation). To allow for the selective screening of lithium-containing particles (spodumene) from the calcined ore, the spodumene crystal structure is changed from the alpha phase to the beta phase during the calcining 104 to obtain beta-spodumene.

[0041] DRX analysis showed that the conversion from α to β was over 90%, achieving 100% conversion.

[0042] The calcining 104 of the spodumene ore can be performed using any energy source, including but not limited to natural gas, propane, heavy oil, biomass, and / or electricity. Calcination 104 can be performed using any calcining equipment, either directly or indirectly, including but not limited to a directly heated rotary kiln, an indirectly heated rotary kiln, a fluidized bed, and / or any other similar equipment. Electrically powered calcining equipment can be heated using electrical resistance, arc plasma torches, microwaves, or any other similar means.

[0043] In some embodiments, the calcining 104 changes the crystal structure of the calcined spodumene particles from alpha to beta by at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more. In a specific embodiment, the crystal structure of all (i.e., 100%) of the calcined spodumene particles is in the beta phase. More specifically, in some embodiments, the crystal structure of the spodumene expands and embrittles during the calcining 104. As used herein, the term "embrittlement" is defined as causing the spodumene particles to transform from an alpha crystal structure to a beta crystal structure. The term "embrittlement" can be further defined as a loss of structural integrity in the spodumene particles (e.g., having one or more cracks).

[0044] Selective screening 106 of the calcined coarse fraction to separate spodumene particles to produce screened spodumene particles is possible because other minerals present in the coarse and fine ore particles subjected to the calcination 104 do not substantially change their crystal structure. Other (non-spodumene) minerals are not significantly embrittled by the calcination 104 because they retain substantially the same crystal structure.

[0045] In one embodiment, the calcining 104 is performed at a temperature between about 950°C and about 1100°C, between about 975°C and about 1080°C, between about 1000°C and about 1070°C, between about 1030°C and about 1060°C, between about 950°C and about 1060°C, between about 950°C and about 1050°C, or at about 1050°C. It should be understood that calcining at temperatures below about 950°C does not cause changes in the spodumene crystal structure, and calcining at temperatures above about 1100°C can soften and melt (liquefy) some other minerals in the ore. Therefore, in one embodiment, the calcining temperature is up to about 1100°C. In some embodiments, the calcining is performed at a temperature of about 1050°C. In some embodiments, the calcining 104 is performed at atmospheric pressure. In other embodiments, calcining is performed for a period of time between about 5 minutes and about 60 minutes, between about 10 minutes and about 50 minutes, between about 15 minutes and about 45 minutes, between about 20 minutes and about 40 minutes, between about 25 minutes and about 40 minutes, or between about 30 minutes and about 35 minutes. The calcining 104 produces a calcined ore comprising calcined spodumene and other minerals such as quartz and / or other gangue materials.

[0046] After calcining 104, the embrittlement of the calcined spodumene can optionally be determined. As used herein, the term "embrittlement" can refer to a measure of the property of a particle that readily loses at least some of its structural integrity (i.e., fractures). The embrittlement is also an indicator of the suitability of the particle for selective screening 106. The embrittlement can be determined at predetermined intervals during operation to control / regulate the process. If a particle is not suitable for selective screening based on its embrittlement, further grinding (selective spodumene grinding) and / or milling is indicated to increase embrittlement and can be performed. The embrittlement can be determined based on direct or indirect analysis of the particle's crystal structure. For example, direct analysis can be performed by observing the crystal structure using a microscope. In another embodiment, indirect analysis can be performed by macroscopic visual inspection or size distribution analysis to determine the embrittlement. If the embrittlement of the calcined spodumene is below a preset threshold, grinding and / or milling is performed to increase the embrittlement to equal or above the preset threshold. In one embodiment, the threshold can be that the size of the spodumene particles is approximately 4 times smaller than that of other (non-spodumene) mineral particles. In other embodiments, the threshold value can be that the spodumene particles have a size that is about 4.25 times smaller, 4.5 times smaller, 5 times smaller, or more times smaller when compared to the size of other (non-spodumene) mineral particles. Once the embrittlement is above the preset threshold value, the calcined spodumene can be subjected to the step of selective screening 106. If the embrittlement of the calcined spodumene is determined to be above the preset embrittlement threshold value, the calcined ore can be directly provided for the selective screening 106. Therefore, in some embodiments, the embrittlement can be additionally determined after the grinding and / or milling to assess whether the grinding and / or milling is sufficient. If necessary, the grinding and / or milling can be performed before or simultaneously with the selective screening 106. Examples of grinding include, but are not limited to: adding steel / ceramic balls to the screen plate to make the spodumene particles embrittled, grinding (attrition) before screening, soft ball milling (soft ball milling) before screening, and combinations thereof. Therefore, in some embodiments, the method also includes determining the embrittlement of the calcined spodumene particles. In other embodiments, the method further comprises subjecting the calcined ore to said grinding and / or pulverizing before or during said selective screening 106 .

[0047] The method of the present disclosure provides selective screening 106 to separate the calcined spodumene particles from other minerals that may be present in the calcined coarse fraction of the ore, thereby obtaining screened spodumene particles. Selective screening can be performed to obtain screened spodumene particles having a size of less than about 300 μm. Selective screening can be performed using a suitable filter (or screen), for example, having an opening (pore size) size between equal to or greater than about 25 μm, equal to or less than about 300 μm, and in some specific embodiments, between about 45 μm and about 300 μm. In some embodiments, the size of the selectively screened spodumene particles is less than 300 μm, less than 290 μm, less than 280 μm, less than 270 μm, less than 260 μm or less than 250 μm. In one embodiment, selective screening 106 includes the use of a vibrating screen, an airflow separator, an airflow separator, a cyclone classifier and / or any other means of separation by size. Vibration and other similar means can be used to facilitate and / or accelerate screening.

[0048] It has been discovered that after calcination 104 and the selective screening step 106, the screened spodumene particles can be further processed using magnetic separation 108 to recover β-spodumene particles from other non-magnetic particles, such as quartz and other gangue minerals. During the magnetic separation process, iron oxide minerals / particles and screened spodumene particles containing a high amount of iron in their β crystal structure are enriched in the magnetic product, while quartz and other gangue minerals are enriched in the non-magnetic product. This is because iron inclusions in the spodumene crystals increase the magnetic susceptibility of the β-spodumene particles during the α-to-β transition. Thus, magnetic separation further improves the quality of the lithium concentrate. This magnetic separation should not be confused with the magnetic separation routinely used upstream in the industry to separate iron oxide from α-spodumene. Rather, magnetic separation step 108 is used to separate magnetic iron-containing β-spodumene from other minerals / particles. One advantage of magnetic separation method 108 is that it can be a dry process, eliminating the need for any wetting, filtering, or drying of the product, thereby reducing the number of steps performed and the overall process cost.

[0049] Generally, iron comes from two different sources: iron-bearing minerals (usually separated from alpha spodumene by magnetic separation) and iron contained within spodumene crystals (alpha and beta). Incorporation of iron into the spodumene crystal structure occurs during the geological formation of the spodumene. The iron contents of alpha and beta spodumene are generally considered to be similar. However, alpha spodumene is non-magnetic. Calcination of alpha spodumene oxidizes the iron contained in its crystal structure and increases its magnetic susceptibility. As a result, beta spodumene is weakly magnetic and can be effectively separated from non-magnetic gangue minerals. The iron content of spodumene crystals varies from one spodumene deposit to another, which affects their magnetic behavior after calcination.

[0050] In some embodiments, magnetic separation is performed using a rare earth roller magnetic separator. Due to the magnetic field applied by the magnet, particles with stronger magnetism drift with the movement of the magnetic roller. This can produce a magnetic concentrate, in this case, β-spodumene particles. Preferably, before the calcination step, iron-containing minerals (which are magnetic) are removed from the non-magnetic α spodumene by magnetic separation. This can be done, for example, by a wet process using a wet high-intensity magnetic separator, or by a dry process using a rare earth roller magnetic separator. However, this is done before the present method (i.e., before step 102). After the calcination step 104, a rare earth roller magnetic separator (high-intensity magnetic field) is used to separate the weakly magnetic β spodumene from the non-magnetic gangue minerals. Preferably, a multi-channel magnetic separator, such as a three-channel (three-roller) magnetic separator, is used to obtain a better quality product.

[0051] Lithium concentrate can be used to obtain lithium salt 110. The lithium salt 110 is obtained from the lithium concentrate by any suitable method. The lithium salt can be a commercially available salt, such as LiOH, Li2O, and / or Li2CO3. Therefore, in some embodiments, the method includes obtaining the lithium salt from the lithium concentrate. In some embodiments, these methods can produce battery-grade lithium carbonate with an impurity content of less than 0.5%.

[0052] In one embodiment, a hydrometallurgical process is performed to obtain LiOH from lithium concentrate. The lithium concentrate is first heated in an autoclave to obtain a slurry. The autoclave heating can be performed, for example, by adding a salt additive (e.g., a sodium salt) and an aqueous phase (e.g., water). The autoclave heating can be performed, for example, at a temperature between about 200° C. and 240° C. and a pressure between about 320 psi and 360 psi (i.e., 2.2-2.48 MPa). The autoclave heating can be performed under stirring. The autoclave heating can be performed for at least 60 minutes. The slurry obtained from the autoclave can then be converted into a suspension, i.e., a mixture of LiOH and CaO (e.g., a slurry), by adding water and CaO to make the lithium in a soluble form. The mixture of LiOH and CaO can then be filtered to obtain a LiOH filtrate containing LiOH. The LiOH is then precipitated by crystallization to obtain LiOH crystals suspended in the solution. In one embodiment, the precipitation is performed by changing the pressure (e.g., vacuum) and / or temperature to evaporate the liquid component of the filtrate. The LiOH crystals can then be separated from the solution by centrifugation or other similar solid / liquid separation methods. By optionally dissolving the LiOH crystals (for example in a dissolution tank), the LiOH crystals can be subjected to a further precipitation (crystallization) step and a separation step to recover more lithium and reduce the impurity content. The precipitated LiOH crystals are then dried to obtain dried LiOH crystals, which can then be optionally packaged. In one example, the drying can be performed at a temperature between 50°C and 90°C, or until all free water is removed and the lithium hydroxide is in the form of a monohydrate. The packaging can be, for example, an airtight bag of packaging.

[0053] In another embodiment, lithium concentrate is autoclaved to obtain a slurry. The autoclave heating can be performed under the same conditions as the autoclave heating of LiOH. The autoclave heating can be performed, for example, by adding a salt additive (e.g., a sodium salt) and an aqueous phase (e.g., water). The autoclave heating can be performed, for example, at a temperature between about 200°C and 240°C and a pressure between about 320 psi and 360 psi (i.e., 2.2-2.48 MPa). The autoclave heating can be performed with stirring. The autoclave heating can be performed for at least 60 minutes. After leaching by autoclave heating, the slurry can be sent to a bicarbonation tank for bicarbonation to obtain a solution containing LiHCO. The bicarbonation step can be performed, for example, by injecting CO at a pressure between 140 psi and 160 psi (i.e., 0.965-1.1 MPa) (i.e., 150 psi / 1.03 MPa and 20°C) at room temperature. The bicarbonation converts the medium-soluble lithium carbonate into lithium bicarbonate that is more soluble in solution (e.g., a slurry in which it is dissolved). The solution is then filtered to remove aluminosilicate residues. The filtrate is heated to 95° C. to remove CO 2 , which can be recycled to the bicarbonation step. The heat-driven CO 2 removal further converts the lithium bicarbonate into lithium carbonate with lower solubility and precipitation. The precipitated lithium carbonate can then be separated from the liquid phase in any suitable manner (e.g., centrifugation). Depending on the quality of the initial raw materials, a second bicarbonation step can optionally be performed to remove impurities. Therefore, removal of impurities can include a second precipitation and centrifugation performed under the same conditions as above. In addition, removal of impurities can optionally also include ion exchange (e.g., ion exchange chromatography) to further improve purity. Finally, the crystals can be dried and packaged.

[0054] In some embodiments, the lithium concentrate contains at least about 3% Li2O. In some embodiments, the other mineral particles of the calcined ore (which are not retained by the selective screening) contain less than 2% Li2O. Since the lithium concentrate is not obtained by the use of chemical additives (e.g., flotation) but by physical separation (i.e., selective screening 106 and magnetic separation 108), in one embodiment, the method of preparing lithium concentrate of the present disclosure is free of chemical reagents and pollutants (e.g., flotation reagents). The absence of chemical pollutants reduces the environmental footprint of the method of the present disclosure when compared to the methods of the prior art including flotation. In fact, the residual waste produced by the present method can be easily processed because it can be free of harmful reagents compared to the residues produced by the prior art.

[0055] The methods of the present disclosure advantageously achieve a lithium recovery rate of at least 80%, at least 85%, at least 87%, at least 88%, at least 89%, or at least 90% in the lithium concentrate. The lithium recovery rate represents the amount of lithium contained in the concentrate divided by the amount of lithium contained in the ROM ore.

[0056] The manufacture of lithium-ion batteries is contemplated within the present disclosure. Lithium salts (e.g., LiOH or Li2CO3) can be obtained by the methods of the present disclosure and incorporated into batteries. For example, lithium can be incorporated into the electrodes of a battery. Methods for manufacturing batteries are well known to those skilled in the art.

[0057] Example

[0058] Lithium concentrate was prepared as follows. Run-of-mine (ROM) ore was first crushed until a sufficient degree of spodumene dissociation was achieved, specifically to a maximum size of 6 to 15 mm, to produce crushed ore particles. The crushed ore particles were screened to separate coarse ore particles (0.9 tonnes) from fine ore particles (0.1 tonnes). The screening process separated 0.1 tonnes of fine ore particles with a size of less than 850 μm.

[0059] The coarse ore particles were calcined by heating at 1050°C under atmospheric pressure. The crystal structure caused the spodumene grains to expand and embrittle, resulting in calcined ore. The other minerals were not significantly embrittled and essentially retained the same crystal structure. Due to the embrittlement of spodumene during the calcination process, the spodumene grains broke or easily broke into smaller grains. The spodumene grains were separated from the other coarse mineral grains by screening to obtain screened lithium concentrate particles. The following procedure was carried out on two ores, labeled Ore 1 (Table 1) and Ore 2 (Table 2).

[0060] 1. Crushing the ore to 6.7mm,

[0061] 2. Use RO-Tap shaker to remove fine particles (less than 850μm).

[0062] 3. The coarse fraction (greater than 850 μm) was magnetically separated to remove iron-containing minerals (using a rare earth roller magnetic separator, one channel, 50 rpm roller speed, 0.13 mm Kevlar belt, 3:1 magnetic configuration, magnetic separator model: Outokumpu Technology High Magnetic Laboratory Separator L / P 10-30),

[0063] 4. Calcine the non-magnetic coarse fraction in a muffle furnace at 1050°C for 30 minutes.

[0064] 5. Use RO-TAP screener to screen calcined ore at 212 microns and 75 microns, and

[0065] 6. Magnetic separation of the 75-212 μm fraction to separate the magnetic beta spodumene from the non-magnetic gangue minerals (same magnetic separator / parameters as used in step 3).

[0066] To obtain lithium salts, lithium concentrate undergoes hydrometallurgical processing. More specifically, the lithium concentrate is mixed with NaCO and water in a stirred autoclave at 180°C-220°C and 340 psi (equivalent to 2.34 MPa) for 60 minutes or longer. During the reaction, the lithium in the spodumene structure is replaced by aqueous sodium ions. As a result, the lithium concentrate forms lithium carbonate, which has moderate solubility. The lithium carbonate is primarily present as a precipitate.

[0067] To produce lithium hydroxide, the slurry exiting the autoclave is converted to convert Li2CO3 into highly soluble LiOH with CaO. The filtered residue is a waste material containing aluminosilicates and CaCO3 (from the reaction between CaO and Li2CO3). The filtrate contains LiOH and is sent to a first crystallizer, where water is evaporated under vacuum to precipitate LiOH. LiOH crystals are separated from the remaining solution by centrifugation. Depending on the initial feed mass, a dissolution step and a second crystallization are optionally performed to reduce the impurity level, followed by centrifugation. Finally, the product is dried (LiOH(H2O)).

[0068] Results are presented for two different ores, Ore 1 (Table 1) and Ore 2 (Table 2). For Ore 1, upgrading a run-of-mine sample containing 1.05% Li₂O by 212 μm screening resulted in a 62.7% Li recovery at a 5.1% Li₂O grade (Table 3), whereas without magnetic separation, only a 3.6% grade was obtained. For Ore 2, upgrading a run-of-mine sample containing 1.11% Li₂O by 212 μm screening resulted in a 93.1% Li recovery at a 5.8% Li₂O grade (Table 4), whereas without magnetic separation, only a 4.9% grade was obtained.

[0069] Table 1 : Characterization of ore 1

[0070] Ore 1 <![CDATA[Li2O]]> quality Li yield ％ ％ ％ raw ore 1.19 100.0 100.0 Greater than 212μm (waste) 0.19 80.0 12.9 N-Mag (waste) 3.51 8.1 23.8 Mag(Concentrate) 6.14 3.9 20.0 Less than 75μm (concentrate) 6.39 8.0 43.3

[0071] Table 2 : Characterization of ore 2

[0072] Ore 2 <![CDATA[Li2O]]> quality Li yield ％ ％ ％ raw ore 1.11 100 100 Greater than 212μm (waste) 0.08 78.5 5.7 N-Mag (waste) 0.38 3.5 1.2 Mag(Concentrate) 4.77 6.9 29.6 Less than 75μm (concentrate) 6.4 11.1 63.5

[0073] Table 3 : Results of Ore 1

[0074] <![CDATA[Li2O]]> quality Li yield No magnetic separation 5.2％ 20.0％ 87.1％ Magnetic separation 6.3％ 11.9％ 63.3％

[0075] Table 4 : Results of Ore 2

[0076] <![CDATA[Li2O]]> quality Li yield No magnetic separation 4.9％ 21.5％ 94.3％ Magnetic separation 5.8％ 18％ 93.1％

[0077] Although the present disclosure has been described in conjunction with specific embodiments of the present disclosure, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations, including those that depart from the present disclosure, as long as the departure is within the scope of known or conventional operation in the art and is applicable to the basic features described herein and falls within the scope of the appended claims. Features described in the context of different aspects and embodiments of the present invention may be used together and / or interchangeably. Similarly, features described in the context of a single embodiment may also be provided separately or in any suitable subcombination.

Claims

1. A method for recovering lithium concentrate from a spodumene-containing ore, the method comprising: Crushing the ore to obtain a fine fraction and a coarse fraction; calcining the coarse fraction, preferably at a temperature of about 950 to about 1100° C., to obtain a calcined coarse fraction comprising spodumene particles having a beta crystal structure; selectively screening the calcined coarse fraction to separate the spodumene particles to produce screened spodumene particles; and / or The screened spodumene particles are subjected to magnetic separation to enrich the spodumene particles and separate non-magnetic pollutants to obtain lithium concentrate.

2. The method of claim 1 , wherein the lithium concentrate comprises at least about 3% Li2O.

3. The method according to claim 1 or 2, wherein the selective screening comprises vibratory screening, air flow sorting, cyclone classification and / or any other means of size separation.

4. The method according to any one of claims 1 to 3, wherein the comminution comprises mechanical grinding and / or milling.

5. The method according to any one of claims 1 to 4, wherein the coarse fraction comprises particles having a size of 850 μm or more.

6. The method according to any one of claims 1 to 5, wherein the coarse fraction comprises particles having a size of 500 μm or more.

7. The process according to claim 5 or 6, wherein the particles of the coarse fraction have a size of up to 15 mm.

8. The method of any one of claims 1 to 7, wherein the spodumene particles have a size of at least about 300 μm.

9. The method according to any one of claims 1 to 8, further comprising obtaining lithium salts from the lithium concentrate.

10. The method according to claim 9, wherein the lithium salt is LiOH, Li2O and / or Li2CO3.

11. The method according to any one of claims 1 to 10, wherein the magnetic separation is performed using a magnetized roller or drum.

12. The method according to any one of claims 1 to 11, wherein a rare earth roller magnetic separator is used in the magnetic separation.

13. The method according to any one of claims 1 to 12, wherein a multi-channel magnetic separator is used in the magnetic separation. The method according to claim 13 , wherein the multi-channel magnetic separator is a three-channel magnetic separator.

15. The method according to any one of claims 1 to 14, further comprising the step of determining the degree of embrittlement of the spodumene particles in the calcined coarse fraction.

16. The method of claim 15, wherein the degree of embrittlement is determined by microscopic observation, macroscopic visual inspection, or size distribution analysis.

17. The method according to claim 15 or 16, wherein if the embrittlement degree of the spodumene particles is below a predetermined threshold, the spodumene particles are further ground and / or pulverized.

18. The method of claim 17, wherein the threshold value is that the size of the spodumene particles is about 4 times smaller, about 4.25 times smaller, 4.5 times smaller, or preferably 5 times smaller than the mineral particles.

19. The method according to any one of claims 1 to 18, further comprising the step of autoclaving the lithium concentrate to produce a slurry.

20. The process according to claim 19, wherein the salt additive and / or the aqueous phase are added during heating of the autoclave.

21. The method according to any one of claims 18 to 20, further comprising biocarbonization of the slurry to produce a solution containing LiHCO3.

22. The method of claim 21, wherein biocarbonization removes impurities.

23. The method according to any one of claims 1 to 22, wherein the impurity content of the produced lithium concentrate is less than 0.5%.

24. The method of any one of claims 1 to 23, wherein calcining the coarse fraction changes the crystal structure of the spodumene particles from an alpha crystal structure to a beta crystal structure.

25. The process according to any one of claims 1 to 23, wherein calcining the coarse fraction is performed using natural gas, propane, heavy oil, biomass and / or electricity.

26. The process according to any one of claims 1 to 25, wherein calcining the coarse fraction is carried out using a directly heated rotary kiln, an indirectly heated rotary kiln and / or a fluidized bed.

27. A lithium ion battery comprising a lithium salt prepared by the method of claim 9 or 10.

28. The lithium ion battery of claim 15, wherein the battery comprises a lithium carbonate grade having an impurity content of less than 0.5%.

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