WO2025097240A1

WO2025097240A1 - Process for extraction of lithium values from spodumene feedstocks

Info

Publication number: WO2025097240A1
Application number: PCT/CA2024/051449
Authority: WO
Inventors: Pierre Gauthier; Daria Camilla BOFFITO; Sasan FAZELI
Original assignee: Central America Nickel Inc
Current assignee: Central America Nickel Inc
Priority date: 2023-11-06
Filing date: 2024-11-01
Publication date: 2025-05-15
Anticipated expiration: 2026-05-06

Abstract

A process for the extraction and recovery of the lithium values from a spodumene feedstock is described herein. More specifically, the process comprises subjection the spodumene feedstock to a thermal activation step, thereby producing a β-spodumene feedstock; leaching the β-spodumene feedstock in an acidic solution while simultaneously sonicating the acidic solution, thereby producing a pregnant solution comprising the lithium values and a leach residue; and recovering the lithium values from the pregnant solution. The process may further comprise raising the pH of the pregnant solution, providing for the precipitation of impurities and a purified pregnant solution; and eluding the purified pregnant solution through at least one solid phase extraction column, thereby producing a solution enriched in the lithium values. The solution enriched in the lithium values may be treated with a source of carbonate, thereby producing a lithium carbonate (Li₂CO₃) precipitate.

Description

TITLE

PROCESS FOR EXTRACTION OF LITHIUM VALUES FROM SPODUMENE FEEDSTOCKS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application 63/596,413, filed November 6, 2023. The contents of the referenced application are incorporated into the present application by reference.

BACKGROUND

1. Field

[0002] This disclosure relates to the field of chemistry. More specifically, but not exclusively, the present disclosure broadly relates to a process for the extraction and recovery of lithium values from a spodumene feedstock. Yet more specifically, the present disclosure relates to a process for the extraction and recovery of lithium values from a spodumene feedstock using ultrasound assisted extraction.

2. Related Art

[0003] The following discussion of the background art is only intended to facilitate an understanding of the process described herein.

[0004] Lithium has gained immense importance in recent years due to its critical role in the development of lithium-ion batteries, which power various devices and electric vehicles. Spodumene [LiAI(SiOs)2], a lithium-rich mineral, has become a primary source for lithium extraction. The process of lithium recovery from spodumene involves several steps, with acid leaching being a crucial step. Historically, sulfuric acid has been widely used for lithium extraction. However, the use of sulfuric acid has certain limitations, including the generation of large amounts of gypsum as a by-product, and a lengthy extraction process. As a result, researchers have explored alternative acids and innovative techniques to improve the efficiency of lithium recovery.

[0005] One notable development in acid leaching is the utilization of hydrochloric acid (HCI). HCI offers a more environmentally friendly alternative to sulfuric acid, as it generates fewer undesirable by-products. Recent studies have demonstrated its effectiveness in improving lithium extraction rates from spodumene feedstocks such as spodumene ores. Furthermore, the addition of ultrasound during leaching has been investigated as a means to intensify the process. Ultrasonication can enhance mass transfer and accelerate the dissolution of lithium from the spodumene feedstock, ultimately leading to higher recovery rates.

[0006] The successful application of ultrasound-assisted leaching (UAEx) has been a significant leap in lithium recovery from spodumene feedstocks. Calcination at elevated temperatures, typically at 1000°C or higher, followed by UAEx using HCI, has demonstrated promising results, with lithium extraction rates exceeding 80%. The use of ultrasound also reduces the leaching time, making the process more time efficient. Studies have explored the role of some of the critical parameters in the leaching process, such as the pH of the eluent for impurity elimination, eluent volume, and flow rate. Furthermore, an understanding of the crystal structure of spodumene, specifically the transition from a- spodumene to p-spodumene through calcination, has contributed significantly to enhanced lithium extraction. This transformation is crucial as p-spodumene exhibits greater reactivity and solubility to acid leaching, leading to improved recovery rates. However, the commercially available processes remain limited in their performance and extraction efficiencies, and continue to impose high energy demands.

[0007] A novel process for the extraction and recovery of lithium from a spodumene feedstock in high yield and purity, that is of an environmentally cleaner design, and overcoming the technical and economic limitations of the existing commercial processes is of commercial interest, especially when considering the growing demand for lithium in crucial markets such as energy storage devices and the manufacture of electric vehicles.

SUMMARY

[0008] The present disclosure broadly relates to a process for the extraction and recovery of lithium values from spodumene feedstocks. In an aspect of the present disclosure, the process for the extraction and recovery of lithium values from spodumene feedstocks comprises an ultrasound assisted extraction step. In a further aspect of the present disclosure, the process for the extraction and recovery of lithium values from spodumene feedstocks comprises leaching a spodumene feedstock in an acidic solution while simultaneously sonicating the acidic solution. In a further aspect of the present disclosure, the process for the extraction and recovery of lithium values from spodumene feedstocks comprises leaching p-spodumene in an acidic solution while simultaneously sonicating the acidic solution. [0009] In an aspect, the present disclosure relates to a process for recovering lithium values from a spodumene feedstock, the process comprising: subjection the spodumene feedstock to a thermal activation step, thereby producing a p-spodumene feedstock; leaching the p-spodumene feedstock in an acidic solution while simultaneously sonicating the acidic solution, thereby producing a pregnant solution comprising the lithium values and a leach residue; and recovering the lithium values from the pregnant solution. In an embodiment, the process further comprises raising the pH of the pregnant solution providing for the precipitation of impurities and a purified pregnant solution; and eluding the purified pregnant solution through at least one solid phase extraction column, thereby producing a solution enriched in the lithium values. In an embodiment, the process further comprises treating the solution enriched in the lithium values with a source of carbonate, thereby producing a lithium carbonate (Li2COs) precipitate. In an embodiment of the present disclosure, the sonication is performed at a frequency ranging from about 20 kHz to about 200 kHz and an amplitude ranging from 1 % to 100%. In an embodiment, the leaching is performed at temperatures ranging between about 20°C to about 100°C. In an embodiment, the leaching is performed at temperatures ranging from about 50°C to about 99°C. In an embodiment, the leaching is performed at a temperature of about 90°C. In an embodiment, the acidic solution is at least one of a sulfuric acid solution, a hydrochloric acid solution, a nitric acid solution, a carbonic acid solution, or a combination of any thereof. In an embodiment, the acidic solution is a hydrochloric acid solution. In an embodiment, the acidic solution comprises a mass percentage ranging from about 5 wt.% to about 100 wt.% of the acid. In an embodiment, the acidic solution comprises a mass percentage ranging from about 15 wt.% to about 80 wt.% of the acid. In an embodiment, the hydrochloric acid solution has a mass percentage of about 36 wt.% HCI. In an embodiment, the hydrochloric acid solution has a concentration of about 6.0 M. In an embodiment, the acidic solution (L) and the spodumene feedstock (S) comprise a mass ratio (L-to-S) not exceeding ten to one (10:1 or 10 kg/kg). In an embodiment, the mass ratio (L-to-S) is about 7. In an embodiment, the mass ratio (L-to-S) is about 5. In an embodiment, the mass ratio (L-to-S) is about 3. In an embodiment, the mass ratio (L-to- S) is about 1. In an embodiment, the leaching is performed over a period ranging from about 0.5 hours to about 3 hours. In an embodiment, the leaching is performed over a period ranging from about 0.5 hours to about 2.5 hours. In an embodiment, the leaching is performed over a period of about 1.5 hours. In an embodiment, the thermal activation step is performed in the presence of CaO at temperatures ranging from about 800°C to about 1350°C. In an embodiment, the spodumene feedstock is maintained at temperatures ranging from about 1000°C to about 1350°C over a period ranging from about 15 minutes to about 1 hour. In an embodiment, the thermal activation step is performed in the presence of CaO at temperatures ranging from about 1000°C to about 1200°C. In an embodiment, the thermal activation step is performed in the presence of CaO at a temperatures of about 1150°C. In an embodiment, the CaO is used in an amount ranging from about 5 wt.% to about 30 wt.%. In an embodiment, the spodumene feedstock is heated at a rate of 5°C/min. In an embodiment, the spodumene feedstock is ground to a particle size of less than about 0.500 millimeter. In an embodiment, the spodumene feedstock is ground to a particle size of less than about 0.125 millimeter. In an embodiment, the spodumene feedstock is ground to a particle size of 75 microns (Pso) or less. In an embodiment, the spodumene feedstock is dried prior to being processed to remove residual moisture. In an embodiment, the leaching is performed batch wise. In an embodiment, the leaching is performed semi-continuously or continuously. In an embodiment, the source of carbonate comprises CO2 gas or a carbonate salt. In an embodiment, the carbonate salt is one or more of sodium carbonate (Na2COs), or calcium carbonate (CaCOs). In an embodiment, the sonication is performed using an external sonication probe. In an embodiment, the sonication is performed using an internal sonication probe.

[0010] Also disclosed in the context of the present disclosure are embodiments 1 to 37. Embodiment 1 is a process for recovering lithium values from a spodumene feedstock, the process comprising: subjection the spodumene feedstock to a thermal activation step, thereby producing a p-spodumene feedstock; leaching the p-spodumene feedstock in an acidic solution while simultaneously sonicating the acidic solution, thereby producing a pregnant solution comprising the lithium values and a leach residue; and recovering the lithium values from the pregnant solution. Embodiment 2 is the process of embodiment 1 , further comprising: raising the pH of the pregnant solution providing for the precipitation of impurities and a purified pregnant solution; and eluding the purified pregnant solution through at least one solid phase extraction column, thereby producing a solution enriched in the lithium values. Embodiment 3 is the process of embodiment 2, further comprising treating the solution enriched in the lithium values with a source of carbonate, thereby producing a lithium carbonate (Li2COs) precipitate. Embodiment 4 is the process of any one of embodiments 1 to 3, wherein the sonication is performed at a frequency ranging from about 20 kHz to about 200 kHz and an amplitude ranging from about 1% to about 100%. Embodiment 5 is the process of any one of embodiments 1 to 4, wherein the leaching is performed at temperatures ranging between about 20°C to about 100°C. Embodiment 6 is the process of embodiment 5, wherein the leaching is performed at temperatures ranging from about 50°C to about 99°C. Embodiment 7 is the process of embodiment 5 or 6, wherein the leaching is performed at a temperature of about 90°C. Embodiment 8 is the process of any one of embodiments 1 to 7, wherein the acidic solution is at least one of a sulfuric acid solution, a hydrochloric acid solution, a nitric acid solution, a carbonic acid solution, or a combination of any thereof. Embodiment 9 is the process of embodiment 8, wherein the acidic solution is a hydrochloric acid solution. Embodiment 10 is the process of embodiment 1 , wherein the acidic solution comprises a mass percentage ranging from about 5 wt.% to about 100 wt.% of the acid. Embodiment 11 is the process of embodiment 10, wherein the acidic solution comprises a mass percentage ranging from about 15 wt.% to about 80 wt.% of the acid. Embodiment 12 is the process of embodiment 9, wherein the hydrochloric acid solution has a mass percentage of about 36 wt.% HCI. Embodiment 13 is the process of embodiment 9, wherein the hydrochloric acid solution has a concentration of about 6.0 M. Embodiment 14 is the process of embodiment 1 , wherein the acidic solution (L) and the spodumene feedstock (S) comprise a mass ratio (L-to-S) not exceeding ten to one (10:1 or 10 kg/kg). Embodiment 15 is the process of embodiment 14, wherein the mass ratio (L-to-S) is about 7. Embodiment 16 is the process of embodiment 14 or 15, wherein the mass ratio (L-to-S) is about 5. Embodiment 17 is the process of any one of embodiments 14 to 16, wherein the mass ratio (L-to-S) is about 3. Embodiment 18 is the process of any one of embodiments 14 to 17, wherein the mass ratio (L-to-S) is about 1. Embodiment 19 is the process of any one of embodiments 1 to 18, wherein the leaching is performed over a period ranging from about 0.5 hours to about 3 hours. Embodiment 20 is the process of embodiment 19, wherein the leaching is performed over a period ranging from about 0.5 hours to about 2.5 hours. Embodiment 21 is the process of embodiment 19 or 20, wherein the leaching is performed over a period of about 1.5 hours. Embodiment 22 is the process of any one of embodiments 1 to 21 , wherein the thermal activation step is performed in the presence of CaO at temperatures ranging from about 800°C to about 1350°C. Embodiment 23 is the process of embodiment 22, wherein the spodumene feedstock is maintained at a temperature ranging from about 1000°C to about 1350°C over a period ranging from about 15 minutes to about 1 hour. Embodiment 24 is the process of embodiment 23, wherein the thermal activation step is performed in the presence of CaO at temperatures ranging from about 1000°C to about 1200°C. Embodiment 25 is the process of embodiment 24, wherein the thermal activation step is performed in the presence of CaO at a temperatures of about 1150°C. Embodiment 26 is the process of any one of embodiments 22 to 25, wherein the CaO is used in an amount ranging from about 5 wt.% to about 30 wt.%. Embodiment 27 is the process of embodiment 22, wherein the spodumene feedstock is heated at a rate of 5°C/min. Embodiment 28 is the process of any one of embodiments 1 to 27, wherein the spodumene feedstock is ground to a particle size of less than about 0.500 millimeter. Embodiment 29 is the process of embodiment 28, wherein the spodumene feedstock is ground to a particle size of less than about 0.125 millimeter. Embodiment 30 is the process of embodiment 28 or 29, wherein the spodumene feedstock is ground to a particle size of 75 microns (Pso) or less. Embodiment 31 is the process of any one of embodiments 1 to 30, wherein the spodumene feedstock is dried prior to being processed to remove residual moisture. Embodiment 32 is the process of embodiment 1 , wherein the leaching is performed batch wise. Embodiment 33 is the process of embodiment 1 , wherein the leaching is performed semi-continuously or continuously. Embodiment 34 is the process of embodiment 3, wherein the source of carbonate comprises CO2 gas or a carbonate salt. Embodiment 35 is the process of embodiment 34, wherein the carbonate salt is one or more of sodium carbonate (Na2COs), or calcium carbonate (CaCOs). Embodiment 36 is the process of any one of embodiments 1 to 35, wherein the sonication is performed using an external sonication probe. Embodiment 37 is the process of any one of embodiments 1 to 35, wherein the sonication is performed using an internal sonication probe.

[0011] The word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one”, but it is also consistent with the meaning of “one or more”, “at least one”, and “one or more than one” unless the content clearly dictates otherwise. Similarly, the word “another” may mean at least a second or more unless the content clearly dictates otherwise.

[0012] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “include” and “includes”) or “containing” (and any form of containing, such as “contain” and “contains”), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0013] As used in this specification and claim(s), the word “consisting” and its derivatives, are intended to be close ended terms that specify the presence of stated features, elements, components, groups, integers, and/or steps, and also exclude the presence of other unstated features, elements, components, groups, integers and/or steps.

[0014] The term “consisting essentially of’, as used herein, is intended to specify the presence of the stated features, elements, components, groups, integers, and/or steps as well as those that do not materially affect the basic and novel characteristic(s) of these features, elements, components, groups, integers, and/or steps.

[0015] The terms “about”, “substantially” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies.

[0016] The foregoing and other advantages and features of the present disclosure will become more apparent upon reading of the following non-restrictive detailed description of illustrative embodiments thereof, with reference to the accompanying drawings/figures. It should be understood, however, that the detailed description and the illustrative embodiments, while indicating specific embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this description.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

[0017] The following figures/drawings form part of the present specification and are included to further demonstrate certain aspects of the present specification. The present specification may be better understood by reference to one or more of these figures/drawings in combination with the detailed description. In the appended drawings/figures:

[0018] FIG. 1 - Illustration of a flowchart generally illustrating the process for the extraction and recovery of lithium values from a spodumene feedstock in accordance with an embodiment of the present disclosure. The process comprises leaching the spodumene feedstock in an acidic solution while simultaneously sonicating the acidic solution.

[0019] FIG. 2 - Illustration of a flowchart illustrating the process for the extraction and recovery of lithium values from a spodumene feedstock, in accordance with an embodiment of the present disclosure. The process comprises leaching the spodumene feedstock in an acidic solution while simultaneously sonicating the acidic solution.

[0020] FIG. 3 - Illustration of the impact of the thermal activation step on the leaching efficiency, in accordance with an embodiment of the present disclosure. [0021] FIG. 4 - Illustration of the impact of ultrasound assisted leaching on the extraction efficiency of the lithium values, in accordance with an embodiment of the present disclosure.

[0022] FIG. 5 - Illustration of an experimental plot illustrating the effect of the CaO (wt.%) on the lithium recovery rate, in accordance with an embodiment of the present disclosure. In this particular embodiment, the thermal activation step was performed at 1150°C.

[0023] FIG. 6 - Illustration of an experimental plot illustrating the effect of the L/S ratio (mL/g) on the lithium recovery rate, in accordance with an embodiment of the present disclosure. In this particular embodiment, the thermal activation step was performed at 1150°C.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0024] The present disclosure relates to a process for the extraction and recovery of lithium values from a spodumene feedstock. In an aspect of the present disclosure, the process for the extraction and recovery of lithium values from a spodumene feedstock comprises an ultrasound assisted extraction step. In a further aspect of the present disclosure, the process for the extraction and recovery of lithium values from a spodumene feedstock comprises leaching the spodumene feedstock in an acidic solution while simultaneously sonicating the acidic solution. In a further aspect of the present disclosure, the process for the extraction and recovery of lithium values from spodumene feedstocks comprises leaching p-spodumene in an acidic solution while simultaneously sonicating the acidic solution. These and other aspects of the disclosure are described in greater detail below.

[0025] The process for the extraction and recovery of lithium values from a spodumene feedstock advantageously comprises an ultrasound assisted extraction step providing for the extraction of the lithium values in high yields.

[0026] In an embodiment of the present disclosure, and with reference to FIGs. 1 and 2, the process may be broadly divided into two sections: (1) a first section aimed at providing a pregnant leach solution comprising the lithium values; and (2) a second section aimed at the isolation of the lithium values from the pregnant leach solution in high yield and purity, advantageously battery grade purity. In an embodiment of the present disclosure, the first section comprises a thermal activation step which advantageous provides for the formation of p-spodumene, and an ultrasound assisted extraction (“leaching”) step. In an embodiment of the present disclosure, the second section comprises a molecular recognition technology-solid phase separation (MRT-SPE) step. The pregnant leach solution obtained following the first section is subjected to one or more pH adjustments providing for the selective precipitation of impurities. The purified pregnant leach solution is then eluded through at least one solid phase extraction column, thereby producing a solution enriched in the lithium values. In an embodiment of the present disclosure, the solid phase extraction column may be advantageously loaded with a crown ether. The lithium values may then be advantageously obtained as a lithium carbonate (Li2COs) precipitate, following treatment of the enriched solution comprising the lithium values with a source of carbonate.

[0027] In an embodiment of the present disclosure, and with reference to FIG. 2, a spodumene sample (obtained from Madagascar) was subjected to a thermal activation step in the presence of CaO (20 wt.%) at 1150°C over a period of 30 minutes. The sample was heated to 1150°C at a rate of 5°C/min. The resulting p-spodumene was then subjected to atmospheric leaching at 90°C using HCI (6M). In an embodiment of the present disclosure, the acidic reaction mixture was characterized by a L/S of 7. The resulting pregnant leach solution (PLS) was then subjected to one or more pH adjustments providing for the selective precipitation of impurities. The purified pregnant leach solution is then eluded through at least one solid phase extraction column, thereby producing a solution enriched in the lithium values. In an embodiment of the present disclosure, the solid phase extraction column may be advantageously loaded with a crown ether. The lithium values may then be advantageously obtained as a lithium carbonate (Li2COs) precipitate. The lithium carbonate advantageously exhibits a purity in excess of 99.9%.

[0028] Spodumene Leaching

[0029] The extraction performance was determined by analyzing the concentration of dissolved lithium in the pregnant leach solution using ICP-MS-MS. Reaction parameters, including but not limited to the thermal activation temperature, the acid concentration, sonication (with or without the use of sonication), the wt.% CaO, and the L/S ratio have an impact on the leaching performance and thus the recovery of the lithium values. In an embodiment of the present disclosure, the spodumene sample is ground to a particle size of 75 pm. Grinding of the feed material provides for increasing the surface area of the feed material available for the subsequent extraction (leaching), in turn providing for enhanced leaching rates. In an embodiment of the present disclosure, the spodumene leaching step is advantageously performed using an ultrasound assisted extraction step, more specifically an acid leaching/sonication step. During the leaching step, any water lost was compensated by the addition of fresh water in order to maintain a fixed S/L ratio in the reactor. In an embodiment of the present disclosure, the atmospheric leaching was conducted as follows: HCI cone. = 6M; Acid/Spodumene Ratio (L/S) = 7; Temperature = 90°C; and Leaching time = 90 minutes.

[0030] Thermal Activation

[0031] In an embodiment of the present disclosure, and with reference to FIG. 3, the effect of the thermal activation step on the recovery of the lithium values was evaluated. In a more specific embodiment of the present disclosure, the thermal activation step, effecting the conversion of a-spodumene to p-spodumene, was advantageously conducted at 1150°C. In the absence of a thermal activation step, the extraction efficiency of the lithium values was only 2.9%. In cases where the spodumene feedstock was subjected to a thermal activation step in the presence of CaO, at a temperature of about 1000°C, the extraction efficiency of the lithium values increased to 35%. When the temperature of the thermal activation step was increased to 1150°C, in the presence of CaO, the extraction efficiency of the lithium values increased to 83%. It is surmised that thermal activation at 1000°C provides for incomplete conversion of the a-spodumene to p- spodumene. At higher temperatures, more of the p-spodumene is obtained.

[0032] Sonication

[0033] Ultrasound advantageously provides for improving the leaching efficiency of the lithium values. The improved leaching efficiency can in part be attributed to a combination of improved heat and mass transfer, surface activation and impact on the solid-liquid interface. Within heterogeneous systems, such as the leaching of the lithium values in the spodumene feed material, the formation of high velocity microjets resulting from transient cavitation collapse, propagate toward the surface of the spodumene feed material leading to pitting and erosion thereby increasing the reactive surface area. Furthermore, transient cavitation results in extreme localized conditions (up to 5000 K and 1000 atm.) resulting in violent collisions and high shear forces. Furthermore, the formation of free radicals during these extreme conditions affect the oxidation potentials of the system. Further advantages to the use of ultrasound in the leaching process of the lithium values include decreased agglomeration, increased access to a reactive surface by breaking down the particulate feed material (increasing the reactive surface area), improving the diffusion rate, and preventing passivation. [0034] In an embodiment of the present disclosure, and with reference to FIG. 4, the effect of sonication on the leaching efficiency of the lithium values was evaluated. In the absence of sonication during the leaching process, the extraction efficiency of the lithium values was about 31 %. When the leaching was performed with sonication, the extraction efficiency of the lithium values increased to about 50%.

[0035] With reference to the spodumene leaching step, and with further reference to FIG. 4, the spodumene feed material may be subjected to an ultrasound assisted extraction step, more specifically an acid leaching/sonication step. This step comprises mixing of the feed material with an aqueous acid solution to provide a slurry and subsequently sonicating the slurry while stirring. The sonication advantageously provides for increased leaching rates, shorter extraction times, and reduced acid consumption. In an embodiment of the present disclosure, the acid leaching/sonication step is performed as a batch process. In a further embodiment of the present disclosure, the acid leaching/sonication step is performed as a continuous process. Following the ultrasound assisted extraction step, a pregnant leach solution comprising the lithium values (as lithium salts) is obtained. In an embodiment of the present disclosure, ultrasound assisted extraction is advantageously used in the processing of a spodumene feed material to extract the lithium values therefrom. In a further embodiment of the present disclosure, the acid leaching/sonication step may be performed at temperatures ranging between 20°C and 100°C. In a further embodiment of the present disclosure, the acid leaching/sonication step may be performed at temperatures ranging between 50°C and 99°C. The use of an ultrasound assisted extraction step advantageously provides for reduced leaching times as well as reduced acid consumption (reduced t/t).

[0036] In an embodiment of the present disclosure, the acid leaching/sonication step is performed using hydrochloric acid, converting the lithium values of the spodumene feed material into the corresponding chlorides.

[0037] CaO wt.%

[0038] With reference to the spodumene thermal activation step, and with further reference to FIG. 5, the amount of CaO was varied between 0 to about 20 wt.%. In these particular embodiments, the activation temperature was set at 1150°C. The extraction efficiency of the lithium values increased significantly with the use of CaO in the thermal activation step. Moreover, increasing the amount of CaO from 0 to about 20 wt.% in the thermal activation step further enhanced the lithium extraction efficiency. These results are indicative of the CaO advantageously providing for improved a to p-spodumene conversion during the thermal activation step. It is surmised that the calcium ions become entwined in the spodumene lattice structure.

[0039] L/S Ratio

[0040] With reference to the spodumene leaching step, and with further reference to FIG. 6, the L/S ratio was varied between 3 and 7. In these particular embodiments, the HCI concentration was 6M, the leaching temperature was set at 80°C, and the leaching duration was set at 90 minutes. The extraction efficiency of the lithium values increased with increasing L/S ratios. It is surmised that at higher L/S ratios, there is increased diffusion and contact between the spodumene particles and the acidic solution.

[0041] In an embodiment of the present disclosure, the acid leaching/sonication step may be advantageously performed using hydrochloric acid (HCI), converting the lithium values of the spodumene feed material into their corresponding chlorides. In embodiments of the present disclosure, the leaching solution comprises from about 5 wt.% to about 100 wt.% HCI; in a further embodiment from about 5 wt.% to about 90 wt.% HCI; in a further embodiment from about 10 wt.% to about 80 wt.% HCI; in a further embodiment from about 15 wt.% to about 70 wt.% HCI; in a further embodiment from about 20 wt.% to about 60 wt.% HCI; in a further embodiment from about 30 wt.% to about 50 wt.% HCI; about 5 wt.% HCI; about 10 wt.% HCI; about 15 wt.% HCI; about 20 wt.% HCI; about 25 wt.% HCI; about 30 wt.% HCI; about 35 wt.% HCI; about 40 wt.% HCI; about 45 wt.% HCI; about 50 wt.% HCI; about 55 wt.% HCI; about 60 wt.% HCI; about 65 wt.% HCI; about 70 wt.% HCI; about 75 wt.% HCI; about 80 wt.% HCI; about 85 wt.% HCI; about 90 wt.% HCI; about 95 wt.% HCI; or about 100 wt.% HCI.

[0042] In an embodiment of the present disclosure, the acid leaching/sonication step may be performed using sulfuric acid (H2SO4), converting the lithium values of the spodumene feed material into their corresponding sulfates. In embodiments of the present disclosure, the leaching solution comprises from about 5 wt.% to about 100 wt.% H2SO4; in a further embodiment from about 5 wt.% to about 90 wt.% H2SO4; in a further embodiment from about 10 wt.% to about 80 wt.% H2SO4; in a further embodiment from about 15 wt.% to about 70 wt.% H2SO4; in a further embodiment from about 20 wt.% to about 60 wt.% H2SO4; in a further embodiment from about 30 wt.% to about 50 wt.% H2SO4; about 5 wt.% H2SO4; about 10 wt.% H2SO4; about 15 wt.% H2SO4; about 20 wt.%

H2SO4; about 25 wt.% H2SO4; about 30 wt.% H2SO4; about 35 wt.% H2SO4; about 40 wt.%

H2SO4; about 45 wt.% H2SO4; about 50 wt.% H2SO4; about 55 wt.% H2SO4; about 60 wt.%

H2SO4; about 65 wt.% H2SO4; about 70 wt.% H2SO4; about 75 wt.% H2SO4; about 80 wt.% H2SO4; about 85 wt.% H2SO4; about 90 wt.% H2SO4; about 95 wt.% H2SO4; or about 100 wt.% H2SO4.

[0043] In an embodiment of the present disclosure, the acid leaching/sonication step may be performed using nitric acid (HNO3), converting the lithium values of the spodumene feed material into their corresponding nitrates. In embodiments of the present disclosure, the leaching solution comprises from about 5 wt.% to about 100 wt.% HNO3; in a further embodiment from about 5 wt.% to about 90 wt.% HNO3; in a further embodiment from about 10 wt.% to about 80 wt.% HNO3; in a further embodiment from about 15 wt.% to about 70 wt.% HNO3; in a further embodiment from about 20 wt.% to about 60 wt.% HNO3; in a further embodiment from about 30 wt.% to about 50 wt.% HNO3; about 5 wt.% HNO3; about 10 wt.% HNO3; about 15 wt.% HNO3; about 20 wt.% HNO3; about 25 wt.% HNO3; about 30 wt.% HNO3; about 35 wt.% HNO3; about 40 wt.% HNO3; about 45 wt.% HNO3; about 50 wt.% HNO3; about 55 wt.% HNO3; about 60 wt.% HNO3; about 65 wt.% HNO3; about 70 wt.% HNO3; about 75 wt.% HNO3; about 80 wt.% HNO3; about 85 wt.% HNO3; about 90 wt.% HNO3; about 95 wt.% HNO3; or about 100 wt.% HNO3.

[0044] In an embodiment of the present disclosure, the ultrasound-assisted extraction may be advantageously performed at the natural frequency of the spodumene feed material. In further embodiments of the present disclosure, the sonication is performed at a frequency ranging from about 20 to about 200 kHz, from about 30 to about 200 kHz; from about 40 to about 200 kHz; from about 50 to about 200 kHz, from about 60 to about 200 kHz; from about 70 to about 200 kHz; from about 80 to about 200 kHz, from about 90 to about 200 kHz; from about 100 to about 200 kHz; from about 110 to about 200 kHz, from about 120 to about 200 kHz; from about 130 to about 200 kHz; from about 140 to about 200 kHz; from about 150 to about 200 kHz, from about 160 to about 200 kHz; from about 170 to about 200 kHz; from about 180 to about 200 kHz; about 20 kHz; about 30 kHz; about 40 kHz; about 50 kHz; about 60 kHz; about 70 kHz; about 80 kHz; about 90 kHz; about 100 kHz; about 110 kHz; about 120 kHz; about 130, about 140 kHz; about 150 kHz; about 160 kHz; about 170 kHz; about 180, about 190 kHz; or about 200 kHz.

[0045] In an embodiment of the present disclosure, the ultrasound-assisted extraction may be advantageously performed at an amplitude ranging from about 1 % to about 100%; from about 5% to about 100%; from about 10% to about 100%; from about 15% to about 100%; from about 20% to about 100%; from about 25% to about 100%; from about 25% to about 100%; from about 30% to about 100%; from about 35% to about 100%; from about 40% to about 100%; from about 45% to about 100%; from about 50% to about 100%; from about 55% to about 100%; from about 60% to about 100%; from about 65% to about 100%; from 70% to about 100%; from about 75% to about 100%; from about 80% to about 100%; from about 85% to about 100%; from about 90% to about 100%; about 5%; about 10%; about 15%; about 20%; about 25%; about 30%; about 35%; about 40%; about 45%;about 50%; about 55%; about 60%; about 65%; about 70%; about 75%; about 80%; about 85%; about 90%;about 95%; or about 100%.

[0046] In an embodiment of the present disclosure, the ultrasound-assisted extraction may be advantageously performed at an ultrasound power output ranging from about 50 W to about 150 W; from about 50 W to about 145 W; from about 55 W to about 140 W; from about 60 W to about 135 W; from about 65 W to about 130 W; from about 70 W to about 125 W; from about 70 W to about 120 W; about 78 W to about 116 W; about 50 W; about 55 W; about 60 W; about 65 W; about 75 W; about 80 W; about 85 W; about 90 W; about 94 W; about 95 W; about 100 W; about 102 W; about 105 W; about 110 W; about 115 W; or about 120 W.

[0047] In an aspect, various ultrasound power outputs were investigated. In an aspect of the present disclosure, the power output ranges between 50 W and 16 000 W. The power output is determined, at least in part, based on the volume to be treated. Smaller volumes require less power. In a further aspect of the present disclosure, the sonication is performed between 200 W/L and 2000 W/L. In a particular embodiment of the present disclosure, the leaching performance was evaluated at ultrasound power outputs ranging between 70 W and 120 W using HCI (6M), while maintaining the slurry temperature at 90°C, the liquid/solid (L/S) ratio at 7, and the leaching time at 90 minutes.

[0048] In an embodiment of the present disclosure, the spodumene feed material is ground to a particle size ranging from about 3 mm to 60 microns; from about 2 mm to 60 microns; from about 1 mm to 60 microns; from about 0.5 mm to 60 microns; to a particle size less than 3 mm; to a particle size less than 2 mm; to a particle size less than 1 mm; to a particle size less than 0.5 mm; to a particle size less than 0.1 mm; to a particle size less than 0.05 mm; to a particle size less than 0.01 mm; to a particle size of about 100 microns; to a particle size of about 90 microns; to a particle size of about 80 microns; to a particle size of about 70 microns; or to a particle size of about 60 microns. In a further embodiment of the present disclosure, the spodumene feedstock is ground to a particle size of less than about 0.500 millimeter. In yet a further embodiment of the present disclosure, the spodumene feedstock is ground to a particle size of less than about 0.125 millimeter. In yet a further embodiment of the present disclosure, the spodumene feedstock is ground to a particle size of 75 mm (Pso) or less.

[0049] General Methods and Materials

[0050] Spodumene samples obtained from Madagascar, originally in the form of cubic rocks, were provided by Auxico resources Canada. The samples were subjected to an initial crushing process performed at Impact Global Solutions Inc. (IGS) (Delson, QC, Canada) and were subsequently further refined into a fine powder having a particle size of 75 pm. The chemical composition was determined using X-ray fluorescence (XRF) and the results illustrated in Table 1. High-purity grade acids (HCI, H2SO4, HNO3) and CaO were procured from Fisher Scientific.

[0051] Table 1 : Spodumene feedstock chemical composition, in accordance with an embodiment of the present disclosure.

[0052] Ultrasound Unit

[0053] The ultrasound unit, in accordance with certain embodiments of the present disclosure, was procured from SYNETUDE S.A.S., France, and featured a 20 KHz ultrasonic probe. The device was calibrated to an 80% amplitude, corresponding to a power dissipation of 102 Watts. The ultrasonic probe was positioned centrally within a controlled-temperature heating bath to ensure uniform energy propagation.

[0054] Leaching Set-up

[0055] The leaching set-up, in accordance with certain embodiments of the present disclosure, was comprised of a 500 mL jacketed glass vessel, a circular water flow bath system, an ultrasound unit, and a heater stirrer. The temperature of the spodumene/acidic solution reaction mixture was regulated using a water flow bath system and a thermocouple.

[0056] Thermal Activation of Spodumene

[0057] Powdered spodumene feed material and calcium oxide were thoroughly mixed and subsequently transferred to a ceramic crucible. The sample was then placed in a muffle furnace, and the heating rate carefully adjusted to 5°C/minute until a temperature ranging between 1000°C and 1150°C was reached. Following the thermal activation, the resulting spodumene slag was crushed and ground using a laboratory mill into a fine powder having a particle size of 75 pm. In an embodiment of the present disclosure, the thermal activation is advantageously performed at 1150°C in the presence of 20 wt.% CaO.

[0058] Acid Leaching

[0059] Fine, thermally activated spodumene slag was combined, in accordance with certain embodiments of the present disclosure, with hydrochloric acid (6M). The mixture was then thoroughly mixed and heated. The leaching was carried out with sonication and without sonication. In an embodiment of the present disclosure, the leaching was performed at temperatures ranging between about 20°C to about 100°C. In a further embodiment of the present disclosure, the leaching was performed at temperatures ranging from about 50°C to about 99°C. In a more particular embodiment, the leaching was performed at a temperature of about 90°C. The extraction performance was determined by analyzing the concentration of lithium in the pregnant leach solution using LC-MS. In an embodiment of the present disclosure, the leaching step is advantageously performed using HCI (6M), an L/S ration of 7, a leaching temperature of 90°C, a leaching time of 90 minutes, and an ultrasound power of 102 kW. [0060] LC-MS Analysis

[0061] The lithium content in the pregnant leach solution was determined by LC-MS using a Perkin Elmer NexION 5000 ICP-MS.

[0062] While the present disclosure has been described with reference to specific examples, it is to be understood that the disclosure is not limited to the disclosed examples. To the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0063] All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

Claims

1. A process for recovering lithium values from a spodumene feedstock, the process comprising: subjection the spodumene feedstock to a thermal activation step, thereby producing a p-spodumene feedstock; leaching the p-spodumene feedstock in an acidic solution while simultaneously sonicating the acidic solution, thereby producing a pregnant solution comprising the lithium values and a leach residue; and recovering the lithium values from the pregnant solution.

2. The process of claim 1 , further comprising: raising the pH of the pregnant solution providing for the precipitation of impurities and a purified pregnant solution; and eluding the purified pregnant solution through at least one solid phase extraction column, thereby producing a solution enriched in the lithium values.

3. The process of claim 2, further comprising treating the solution enriched in the lithium values with a source of carbonate, thereby producing a lithium carbonate (Li2COs) precipitate.

4. The process of any one of claims 1 to 3, wherein the sonication is performed at a frequency ranging from about 20 kHz to about 200 kHz and an amplitude ranging from about 1 % to about 100%.

5. The process of any one of claims 1 to 4, wherein the leaching is performed at temperatures ranging between about 20°C to about 100°C.

6. The process of claim 5, wherein the leaching is performed at temperatures ranging from about 50°C to about 99°C.

7. The process of claim 5 or 6, wherein the leaching is performed at a temperature of about 90°C.

8. The process of any one of claims 1 to 7, wherein the acidic solution is at least one of a hydrochloric acid solution, a sulfuric acid solution, a nitric acid solution, a carbonic acid solution, or a combination of any thereof.

9. The process of claim 8, wherein the acidic solution is a hydrochloric acid solution.

10. The process of claim 1 , wherein the acidic solution comprises a mass percentage ranging from about 5 wt.% to about 100 wt.% of the acid.

11. The process of claim 10, wherein the acidic solution comprises a mass percentage ranging from about 15 wt.% to about 80 wt.% of the acid.

12. The process of claim 9, wherein the hydrochloric acid solution has a mass percentage of about 36 wt.% HCI.

13. The process of claim 9, wherein the hydrochloric acid solution has a concentration of about 6.0 M.

14. The process of claim 1 , wherein the acidic solution (L) and the spodumene feedstock (S) comprise a mass ratio (L-to-S) not exceeding ten to one (10:1 or 10 kg/kg).

15. The process of claim 14, wherein the mass ratio (L-to-S) is about 7.

16. The process of claim 14 or 15, wherein the mass ratio (L-to-S) is about 5.

17. The process of any one of claims 14 to 16, wherein the mass ratio (L-to-S) is about 3.

18. The process of any one of claims 14 to 17, wherein the mass ratio (L-to-S) is about 1.

19. The process of any one of claims 1 to 18, wherein the leaching is performed over a period ranging from about 0.5 hours to about 3 hours.

20. The process of claim 19, wherein the leaching is performed over a period ranging from about 0.5 hours to about 2.5 hours.

21. The process of claim 19 or 20, wherein the leaching is performed over a period of about 1.5 hours.

22. The process of any one of claims 1 to 21 , wherein the thermal activation step is performed in the presence of CaO at temperatures ranging from about 800°C to about 1350°C.

23. The process of claim 22, wherein the spodumene feedstock is maintained at a temperature ranging from about 1000°C to about 1350°C over a period ranging from about 15 minutes to about 1 hour.

24. The process of claim 23, wherein the thermal activation step is performed in the presence of CaO at temperatures ranging from about 1000°C to about 1200°C.

25. The process of claim 24, wherein the thermal activation step is performed in the presence of CaO at a temperatures of about 1150°C.

26. The process of any one of claims 22 to 25, wherein the CaO is used in an amount ranging from about 5 wt.% to about 30 wt.%.

27. The process of claim 22, wherein the spodumene feedstock is heated at a rate of 5°C/min.

28. The process of any one of claims 1 to 27, wherein the spodumene feedstock is ground to a particle size of less than about 0.500 millimeter.

29. The process of claim 28, wherein the spodumene feedstock is ground to a particle size of less than about 0.125 millimeter.

30. The process of claim 28 or 29, wherein the spodumene feedstock is ground to a particle size of 75 microns (Pso) or less.

31. The process of any one of claims 1 to 30, wherein the spodumene feedstock is dried prior to being processed to remove residual moisture.

32. The process of claim 1 , wherein the leaching is performed batch wise.

33. The process of claim 1 , wherein the leaching is performed semi-continuously or continuously.

34. The process of claim 3, wherein the source of carbonate comprises CO2 gas or a carbonate salt.

35. The process of claim 34, wherein the carbonate salt is one or more of sodium carbonate (Na2COs), or calcium carbonate (CaCOs).

36. The process of any one of claims 1 to 35, wherein the sonication is performed using an external sonication probe.

37. The process of any one of claims 1 to 35, wherein the sonication is performed using an internal sonication probe.