Lithium recovery from lithium iron phosphate cathodic material

Abstract

According to the invention there is provided a process comprising admixing lithium iron phosphate (LFP), an oxidizing agent, carbon dioxide, and water; separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture.

Description

LITHIUM RECOVERY FROM LITHIUM IRON PHOSPHATE CATHODIC MATERIALField of the Invention

[0001] The present invention relates to the process of recovering lithium carbonate from a lithium iron phosphate cathodic material.Background of the Invention

[0002] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0003] While a significant proportion of the work on recycling battery materials focuses on post-consumer or post-battery-assembly recycled material (e.g., black mass), the process herein is preferentially focused on the recycling or recovery of lithium from LFP that was produced for use in lithium ion batteries.

[0004] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0005] Although the invention will be described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.Summary of the Invention

[0006] According to a first aspect of the present invention there is provided a process comprising:

[0007] admixing lithium iron phosphate (LFP), an oxidizing agent, carbon dioxide, and water;

[0008] separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture.

[0009] In an embodiment, admixing the LFP, oxidizing agent, carbon dioxide, and water includes:

[0010] admixing the LFP and the oxidizing agent; and then

[0011] admixing the carbon dioxide and water with the admixture of LFP and oxidizing agent.

[0012] In an embodiment, admixing the LFP and the oxidizing agent further includes admixing the LFP, the oxidizing agent, and water.

[0013] In an embodiment, admixing the LFP, oxidizing agent, carbon dioxide, and water includes:

[0014] admixing the LFP, carbon dioxide, and water; and then

[0015] admixing the oxidizing agent with the admixture of LFP, carbon dioxide, and water.

[0016] In an embodiment, admixing the LFP, oxidizing agent, carbon dioxide, and water includes the contemporaneous admixing of LFP, oxidizing agent, carbon dioxide, and water.

[0017] In an embodiment, admixing the LFP, oxidizing agent, carbon dioxide, and water includes admixing an aqueous solution of the LFP with the oxidizing agent; and then admixing therewith carbon dioxide.

[0018] In an embodiment, the oxidizing agent is selected from hydrogen peroxide, peroxyacetic acid, oxygen, and / or ozone.

[0019] In an embodiment, the oxidizing agent is an aqueous solution of hydrogen peroxide, peroxyacetic acid, oxygen, and / or ozone.

[0020] In an embodiment, the oxidizing agent is an aqueous solution of about 3 wt.% to about 60 wt.%, about 3 wt.% to about 45 wt.%, about 3 wt.% to about 30 wt.%, or about 3 wt. % to about 15 wt.% hydrogen peroxide.

[0021] In an embodiment, the oxidizing agent includes ozone and the process includes providing oxygen to an ozone generator and thereafter admixing generated ozone with the LFP.

[0022] In an embodiment, the ozone generator is a UV generator.

[0023] In an embodiment, the LFP, oxidizing agent, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C, about 75 °C to about 250 °C, about 100 °C to about 250 °C, about 100 °C to about 200 °C, or about 100 °C to about 175 °C; and at a pressure of about 80 to about 300 bar, about 80 to about 250 bar, about 80 to about 200 bar, about 80 to about 175 bar, about 80 to about 150 bar, or about 100 to about 150 bar.

[0024] In an embodiment, the oxidizing agent is oxygen; and

[0025] the LFP, oxygen, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300 bar.

[0026] In an embodiment, the oxidizing agent is ozone; and

[0027] the LFP, ozone, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300 bar.

[0028] In an embodiment, the oxidizing agent is hydrogen peroxide; and

[0029] the LFP, hydrogen peroxide, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300 bar.

[0030] In an embodiment, the hydrogen peroxide concentration in the admixture is about 1 wt.% to about 30 wt.%, about 2.5 wt.% to about 30 wt.%, about 5 wt.% to about 30 wt.%, or about 5 wt.% to about 20 wt.%.

[0031] In an embodiment, the carbon dioxide is supercritical CO2.

[0032] In an embodiment, separating the aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture includes:

[0033] filtering the admixture and recovering a filtrate which includes the aqueous solution.

[0034] In an embodiment, separating the aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture includes:

[0035] centrifuging the admixture and recovering a filtrate which includes the aqueous solution.

[0036] In an embodiment, the process further comprises crystallizing lithium carbonate from the aqueous solution that includes lithium carbonate and / or lithium bicarbonate.

[0037] In an embodiment, the process further comprises distilling water from the aqueous solution that includes lithium carbonate and / or lithium bicarbonate and precipitating lithium carbonate.

[0038] In an embodiment, the process further comprises providing the LFP by the pyrolysis of a cathodic material.

[0039] In an embodiment, the cathodic material is an off-specification lithium iron phosphate cathodic material.

[0040] In an embodiment, the pyrolysis of the cathodic material is at a temperature of about 200 to about 800 °C, about 200 to about 700 °C, about 200 to about 600 °C, about 300 to about 600 °C, or about 400 to about 600 °C.

[0041] According to a second aspect of the present invention there is provided a process comprising:

[0042] providing to a lithium iron phosphate (LFP) an admixture flux that includes an oxidizing agent, carbon dioxide, and water; and

[0043] separating an effluent from the LFP that includes lithium carbonate and / or lithium bicarbonate.

[0044] In an embodiment, the admixture flux includes supercritical CO2.

[0045] In an embodiment, the admixture flux is provided to the LFP at a temperature ofabout 50 to about 250 °C; and at a pressure of about 80 to about 300 bar.

[0046] In an embodiment, the admixture flux is provided to the LFP and the effluent is separated from the LFP as a continuous process.

[0047] In an embodiment, the admixture flux fluidizes the LFP thereby commixing the LFP and the admixture flux.

[0048] According to a third aspect of the present invention there is provided a process comprising:

[0049] commixing lithium iron phosphate (LFP), an oxidizing agent, carbon dioxide, and water for a reaction time of about 5 min to about 12 hours at a reaction temperature of about 50 to about 300 °C and at a reaction pressure of about 80 to about 300 bar; and thereafter separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture.

[0050] In an embodiment, commixing the admixture includes engaging a paddle mixer within the admixture.

[0051] In an embodiment, commixing the admixture includes sonicating the admixture.

[0052] In an embodiment, the admixture includes a LFP to water mass ratio of about 1 : 100, about 1 :90, about 1 :80, about 1 :70, about 1 :60, about 1 :50, about 1 :40, about 1 :30, about 1 :20, about 1 : 10, about 1 :9, about 1 :8, about 1 :7, about 1 :6, about 1 :5, about 1 :4, about 1 :3, or about 1:2.

[0053] In an embodiment, the admixture includes an oxidizing agent to LFP molar ratio of 10: 1 to about 1 : 1, about 9: 1 to about 1 : 1, about 8: 1 to about 1 : 1, about 7: 1 to about 1 : 1, about 6: 1 to about 1 : 1, about 5:1 to about 1 : 1, about 4:1 to about 1 : 1, about 3: 1 to about 1 : 1, or about 2: 1 to about 1:1.Brief Description of the Figures

[0054] The first aspect of the invention is a process that includes admixing lithium iron phosphate (LFP), an oxidizing agent, carbon dioxide, and water; separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture.

[0055] The second aspect of the invention is a process that includes providing to a lithium iron phosphate (LFP) an admixture flux that includes an oxidizing agent, carbon dioxide, and water; and separating an effluent from the LFP that includes lithium carbonate and / or lithium bicarbonate.

[0056] The third aspect of the invention is a process that includes admixing lithium ironphosphate (LFP), an oxidizing agent, carbon dioxide, and water; commixing the LFP, oxidizing agent, carbon dioxide, and water for a reaction time of about 5 min to about 12 hours at a reaction temperature of about 50 to about 300 °C and at a reaction pressure of about 80 to about 300 bar; and thereafter separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture.

[0057] For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawing figures wherein:

[0058] Figure l is a Figure 1 shows a first preferred procedure;

[0059] Figure 2 shows a modification of the procedure of Fig. 1 and features distinct oxidation and extraction steps as well as ozone generation and carbon dioxide recycling;

[0060] Figure 3 shows a modification of the above procedures and features a pressure reduction step wherein carbon dioxide is captured and recycled;

[0061] Figure 4 shows another modification of the above procedures and features the addition of an admixture flux of water, supercritical carbon dioxide, and an oxidant to the pyrolyzed LFP;

[0062] Figure 5 shows yet another modification of the above procedures and features a first reactor (reactor A) wherein the pyrolyzed LFP is converted to an iron(III) slurry and a second reactor (reactor B) wherein supercritical CO2 is applied and a lithium bicarbonate slurry is produced;

[0063] Figure 6 shows still another modification of the above procedures and features a first reactor (oxidation reactor) wherein the pyrolyzed LFP is converted to an iron(III) slurry in the presence of carbon dioxide and a second reactor (scCCh extractor) wherein the carbon dioxide is converted to supercritical CO2 and a lithium bicarbonate slurry is produced; and

[0064] Figure 7 shows a modification of the procedure of Fig. 1 wherein the pyrolysis of the LFP feedstock is omitted.

[0065] While specific embodiments are illustrated in the figures, with the understanding that the disclosure is intended to be illustrative, these embodiments are not intended to limit the invention described and illustrated herein.Detailed Description of a Preferred Embodiment

[0066] Objects, features, and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention,are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

[0067] Herein, the use of 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.”

[0068] The term “about” means, in general, the stated value plus or minus 5%.

[0069] The use of the term “or” in the claims is used to mean “and / or” unless explicitly indicated to refer to alternatives only or the alternative are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and / or.”

[0070] As used herein, the term “comprising” means “including”. Variations of the word “comprising”, such as “comprise” and “comprises”, have correspondingly varied meanings. As used herein, the terms “including” and “comprising” are non-exclusive. As used herein, the terms “including” and “comprising” do not imply that the specified integer(s) represent a major part of the whole.

[0071] The transitional phrase “consisting of’ excludes any element, step, or ingredient not specified. If in the claim, such would close the claim to the inclusion of materials other than those recited except for impurities ordinarily associated therewith. When the phrase “consisting of’ appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

[0072] The transitional phrase “consisting essentially of’ is used to define a composition, process or method that includes materials, steps, features, components, or elements, in addition to those literally disclosed, provided that these additional materials, steps, features, components, or elements do not materially affect the basic and novel characteristic(s) of the claimed invention. The term “consisting essentially of’ occupies a middle ground between "comprising" and “consisting of’.

[0073] A first embodiment is a process of recovering lithium, for example lithium carbonate, from lithium iron phosphate (LFP), preferably off-specification LFP or industrially recycled LFP.

[0074] While a significant proportion of the work on recycling battery materials focuses on post-consumer or post-battery-assembly recycled material (e.g., black mass), the process herein is preferentially focused on the recycling or recovery of lithium from LFP that was produced foruse in lithium ion batteries but for one reason or another is unsuitable or unused in said lithium ion batteries. Accordingly, the process includes admixing the LFP, scrap LFP, with an oxidizing agent, carbon dioxide (preferably supercritical CO2), and water. Thereafter, the process includes separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture.

[0075] While different methods of admixing the LFP, oxidizing agent, carbon dioxide, and water are able to be envisioned, in one instance, the process includes admixing the LFP and the oxidizing agent and then or thereafter admixing the carbon dioxide and water with the admixture of LFP and oxidizing agent. Admixing the LFP and the oxidizing agent can be accomplished with or without water depending on the nature of the oxidizing agent. In one preferable instance, the LFP and oxidizing agent are admixed with water, for example by admixing a solution of the oxidizing agent in water with the LFP.

[0076] In another instance, the LFP, carbon dioxide, and water are admixed and thereafter the oxidizing agent is admixed with the admixture of LFP, carbon dioxide, and water. In yet another instance, admixing the LFP, oxidizing agent, carbon dioxide, and water includes the contemporaneous admixing of LFP, oxidizing agent, carbon dioxide, and water. In still yet another instance, admixing the LFP, oxidizing agent, carbon dioxide, and water includes admixing an aqueous solution of the LFP with the oxidizing agent; and then admixing therewith carbon dioxide.

[0077] Notably and herewith, a first example includes forming at one step of the process an admixture that includes the LFP, the oxidizing agent, carbon dioxide, and water. A second example includes an admixture of the LFP and the oxidizing agent, and thereafter admixing said first admixture with carbon dioxide to extract a lithium bicarbonate.

[0078] Herein, the oxidizing agent can be selected from hydrogen peroxide, peroxyacetic acid, oxygen, and / or ozone. In one example, the oxidizing agent is selected from the group consisting of hydrogen peroxide, peroxyacetic acid, oxygen, and / or ozone. In another example, the oxidizing agent is an aqueous solution of hydrogen peroxide, peroxyacetic acid, oxygen, and / or ozone. In one preferable instance, the oxidizing agent is an aqueous solution of about 3 wt.% to about 60 wt.%, about 3 wt.% to about 45 wt.%, about 3 wt.% to about 30 wt.%, or about 3 wt. % to about 15 wt.% hydrogen peroxide. In another instance, the oxidizing agent includes ozone and the process includes providing oxygen to an ozone generator and thereafter admixing generated ozone with the LFP. The generated ozone can be premixed with water and then the ozonated water can be admixed with the LFP. Notably, the ozone generator can be a UVgenerator.

[0079] While the LFP, oxidizing agent, carbon dioxide, and water can be admixed at a variety of temperatures and pressures, the components are preferably admixed at a temperature of about 50 °C to about 250 °C, about 75 °C to about 250 °C, about 100 °C to about 250 °C, about 100 °C to about 200 °C, or about 100 °C to about 175 °C; and at a pressure of about 80 to about 300 bar, about 80 to about 250 bar, about 80 to about 200 bar, about 80 to about 175 bar, about 80 to about 150 bar, or about 100 to about 150 bar. Notably, the components are preferably admixed at a temperature and pressure where the carbon dioxide would be supercritical. In a preferable instance, the oxidizing agent is oxygen and the LFP, oxygen, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300 bar.

[0080] In another preferable instance, the oxidizing agent is ozone and the LFP, ozone, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300 bar. In still another preferable instance, the oxidizing agent is hydrogen peroxide and the LFP, hydrogen peroxide, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300 bar. The hydrogen peroxide concentration in this admixture can be about 1 wt.% to about 30 wt.%, about 2.5 wt.% to about 30 wt.%, about 5 wt.% to about 30 wt.%, or about 5 wt.% to about 20 wt.%.

[0081] In one preferred instance, admixing the LFP with the oxidizing agent, carbon dioxide, and water provides in one step and / or in one pot the oxidation of the iron, the release of a lithium cation, and the formation of an aqueous lithium bicarbonate. The process thereafter preferably includes separating the aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture of the spent-LFP and / or LFP and / or other iron phosphate byproducts. The separation process can include filtering the admixture and recovering a filtrate which includes the aqueous solution which includes lithium carbonate and / or lithium bicarbonate.

[0082] In another instance, the separation process can include centrifuging the admixture and recovering a filtrate which includes the aqueous solution. In still another instance, the separation process can include one or more steps wherein iron and phosphorus containing byproducts are removed from the solution / slurry and a filtrate that includes lithium carbonate and / or lithium bicarbonate is provided.

[0083] While in certain instances solutions of lithium carbonate and / or lithium bicarbonate may be desired, the process preferably further includes crystallizing lithium carbonate from theaqueous solution that includes lithium carbonate and / or lithium bicarbonate. In one example, the process further includes distilling water from the aqueous solution that includes lithium carbonate and / or lithium bicarbonate and precipitating lithium carbonate.

[0084] Notably, increasing the temperature of the aqueous solution can have a two fold impact, increasing the temperature can decrease the concentration of carbon dioxide in the aqueous solution thereby reducing the solubility of the lithium carbonate and providing the crystallization of the lithium carbonate, and increasing the temperature of the aqueous solution can facilitate the evaporation of water thereby increasing the concentration of the lithium carbonate and providing the crystallization of the lithium carbonate. Notably, the concentration of carbon dioxide in the solution can be decreased by exposing the aqueous solution to a vacuum or sparging an inert gas (e.g., nitrogen or argon) through the aqueous solution.

[0085] As described above, the process includes admixing a lithium iron phosphate (LFP) with the oxidizing agent, carbon dioxide, and water and the process can further include providing the LFP by the pyrolysis of a cathodic material. In a preferable instance, the cathodic material is an off-specifi cation lithium iron phosphate cathodic material. In another instance, the cathodic material is a lithium iron phosphate particle coated with a carbon or graphitic coating. In still another instance, the lithium iron phosphate particle is coating with pitch. Herewith, the pyrolysis of the cathodic material is at a temperature of about 200 to about 800 °C, about 200 to about 700 °C, about 200 to about 600 °C, about 300 to about 600 °C, or about 400 to about 600 °C. In one example, the pyrolysis is in air; in another example, the pyrolysis is under an inert atmosphere (e.g., nitrogen or argon); in yet another example, pyrolysis is a vacuum pyrolysis.

[0086] Another embodiment of producing lithium carbonate from lithium iron phosphate can feature a process that includes providing to a lithium iron phosphate (LFP) an admixture flux that includes an oxidizing agent, carbon dioxide, and water; and separating an effluent from the LFP that includes lithium carbonate and / or lithium bicarbonate. In a preferable instance, the admixture flux includes supercritical CO2. In one example, the admixture flux is provided to the LFP at a temperature of about 50 to about 250 °C and at a pressure of about 80 to about 300 bar.

[0087] Herewith, the temperature can be about 40 to about 400 °C yet is preferably about 40 to about 300, about 40 to about 250, about 50 to about 250, about 50 to about 200, about 50 to about 175, about 50 to about 150, about 50 to about 125, or about 50 to about 100 °C. The pressure can be about 75 to about 400 bar yet is preferably about 80 to about 350, about 80 to about 300, about 80 to about 250, about 80 to about 200, about 80 to about 175, about 80 to about 150, about 80 to about 135, about 80 to about 125, about 80 to about 115, about 80 toabout 110, about 80 to about 105, or about 80 to about 100 bar.

[0088] In a particularly preferable instance, the process of producing lithium carbonate from LFP is continuous wherein, for example, the admixture flux is provided to the LFP and the effluent is separated from the LFP as a continuous process. In one example, the admixture flux is prepared external to the LFP and then pumped or passed through a reactor containing the LFP; thereafter the effluent is separated from the LFP and passed to a further processing step, e.g., crystallization of lithium carbonate from the extracted lithium carbonate and / or lithium bicarbonate.

[0089] In another example, the admixture flux fluidizes the LFP thereby commixing the LFP and the admixture flux. The fluidization of the LFP can be within a fluidized bed reactor or can be in a mixing volume wherein a slurry of the LFP and the admixture flux are fluidly conveyed to a separating unit.

[0090] Yet another embodiment includes commixing the LFP, oxidizing agent, carbon dioxide, and water for a reaction time of about 5 min to about 12 hours at a reaction temperature of about 50 to about 300 °C and at a reaction pressure of about 80 to about 300 bar; and thereafter separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture. Herewith, the reaction time can be about 5 min to about 12 hours yet is preferably about 5 min to about 10 h, about 5 min to about 8 h, about 5 min to about 6 h, about 5 min to about 4 h, about 5 min to about 2 h, about 5 min to about 100 min, about 5 min to about 80 min, about 5 min to about 60 min, about 5 min to about 45 min, about 5 min to about 30 min, or about 5 min to about 15 min. In another preferable instance, the reaction time can be even shorter, for example the reaction time can be about 10 sec to about 5 min, about 10 sec to about 4 min, about 10 sec to about 3 min, about 10 sec to about 2 min, or about 10 sec to about 1 min.

[0091] The temperature can be about 40 to about 400 °C yet is preferably about 40 to about 300, about 40 to about 250, about 50 to about 250, about 50 to about 200, about 50 to about 175, about 50 to about 150, about 50 to about 125, or about 50 to about 100 °C. The pressure can be about 75 to about 400 bar yet is preferably about 80 to about 350, about 80 to about 300, about 80 to about 250, about 80 to about 200, about 80 to about 175, about 80 to about 150, about 80 to about 135, about 80 to about 125, about 80 to about 115, about 80 to about 110, about 80 to about 105, or about 80 to about 100 bar.

[0092] The commixing of the slurry of LFP, oxidizing agent, carbon dioxide, and water can be accomplished via turbulent flow of the slurry. In another example, commixing the slurry caninclude engaging a paddle mixer within the admixture. In still another example, commixing the slurry can include sonicating the admixture. Other examples of equipment applicable to the commixing of the slurry include drum mixers, screw mixers, tumbler mixers, ribbon mixers, emulsifiers, planetary mixers, and static mixers.

[0093] Herein, relative concentrations of materials in the admixtures / slurries can be important. In one instance, the admixture / slurry can include a LFP to water mass ratio of about 1 : 100, about 1 :90, about 1 :80, about 1 :70, about 1:60, about 1 :50, about 1 :40, about 1 :30, about 1:20, about 1 : 10, about 1 :9, about 1 :8, about 1 :7, about 1 :6, about 1 :5, about 1 :4, about 1 :3, or about 1 :2. Notably, the LFP to water ratio can be varied depending on the type of reactor / reach on volume utilized for the process. For example, if the admixture / slurry is commixed with a paddle mixer the relative mass ratio of water can be lower, i.e., the slurry thicker, than if the commixing is via fluidization in a fluidizing column. In another instance, the admixture / slurry can include an oxidizing agent to LFP molar ratio of 10: 1 to about 1 : 1, about 9: 1 to about 1 : 1, about 8: 1 to about 1 : 1, about 7: 1 to about 1 : 1, about 6: 1 to about 1 : 1, about 5: 1 to about 1 : 1, about 4: 1 to about 1 : 1, about 3: 1 to about 1 :1, or about 2: 1 to about 1:1.

[0094] A further understanding of the described embodiments can be ascertained from the drawing figures wherein Figure 1 depicts one preferred procedure for the production of lithium carbonate from a LFP feedstock. Therein, a LFP feedstock is fed to a furnace, e.g., a rotary kiln or a batch kiln. The LFP feedstock is heated to a predetermined temperature for a predetermined time thereby providing a material feed for the extractor. The extractor can be charged directly with supercritical CO2 or can be charged with liquid and / or gaseous CO2 that is then converted to supercritical CO2. The extractor is further charged with the oxidant and water. This slurry is admixed at the predetermined temperature and pressure wherein the oxidant preferentially oxidizes the iron, and an aqueous lithium bicarbonate slurry is generated.

[0095] The aqueous lithium bicarbonate slurry is separated into solid residue and a filtrate via a first solid-liquid separation apparatus (Sep. A), e.g., a filter, a centrifuge, or a hydrocyclone. Thereafter the filtrate is added to a crystallizer wherein a concentration of water and / or CO2 is reduced and lithium carbonate is precipitated. The desired lithium carbonate is then separated from the mother liquor (filtrate) which can be returned to the extractor or disposed of.

[0096] Figure 2 depicts another preferred procedure for the production of lithium carbonate. Therein and similar to Figure 1, a LFP feedstock is fed to a furnace, e.g., a rotary kiln or a batch kiln. The LFP feedstock is heated to a predetermined temperature for a predeterminedtime thereby providing a material feed for the oxidizer. In addition to the material feed, the oxidizer can be charged with water and an oxidant, as depicted in Fig. 2 the oxidant is ozone and is generated from an oxygen or air feed through an ozone generator. In an example, the as generated ozone can be admixed with the water prior to charging the oxidizer or the components can be added separately. In another example, the water can be admixed and bubbles of oxygen or air can be suspended in the water and this solution can then be passed through the ozone generator prior to addition to the material feed. In still another example, the water and oxygen (or air) can be admixed with the material feed and then subjected to the ozone generator, e.g., a UV ozone generator.

[0097] Thereafter the material feed with the oxidized iron can be admixed with carbon dioxide (e.g., supercritical CO2) in an extractor. Therein, an aqueous lithium bicarbonate slurry is generated. The aqueous lithium bicarbonate slurry is separated into solid residue and a filtrate via a first solid-liquid separation apparatus (Sep. A), e.g., a filter, a centrifuge, or a hydrocyclone. Thereafter the filtrate is added to a crystallizer wherein a concentration of water and / or CO2 is reduced and lithium carbonate is precipitated. The separated CO2 and water can themselves be separated with the CO2 being recycled in the system. Optionally, the water can be recycled also. The desired lithium carbonate is then separated from the mother liquor (filtrate) which can be returned to the extractor or disposed of.

[0098] Figure 3 depicts yet another preferred procedure for the production of lithium carbonate. Therein and similar to Fig. 1, a LFP feedstock is fed to a furnace and thereafter to an extractor to which is admixed the oxidant, supercritical carbon dioxide, and water. Figure 3 further depicts a pressure reducer or pressure reduction step wherein carbon dioxide is removed from the admixture and preferentially recovered and recycled for further extractions.

[0099] Figure 4 depicts still yet another preferred procedure for the production of lithium carbonate. Therein and similar to Figure 1, a LFP feedstock is fed to a furnace, e.g., a rotary kiln or a batch kiln. The LFP feedstock is heated to a predetermined temperature for a predetermined time thereby providing a material feed for the extractor. The extractor carrying the pyrolyzed LFP (material feed) is further fed an admixture flux that includes an oxidizing agent, carbon dioxide, and water. Notably, the admixture flux can include carbon dioxide or supercritical carbon dioxide depending on the temperature and pressure of the admixture flux. Preferably within the extractor, the carbon dioxide is supercritical carbon dioxide. The commixing of the oxidant and the pyrolyzed LFP can oxidize the iron and generate an aqueous lithium bicarbonate slurry. The aqueous lithium bicarbonate slurry is separated into solid residue and afiltrate via a first solid-liquid separation apparatus (Sep. A), e.g., a filter, a centrifuge, or a hydrocyclone. Thereafter the filtrate is added to a crystallizer wherein a concentration of water and / or CO2 is reduced and lithium carbonate is precipitated. The separated CO2 and water can themselves be separated with the CO2 being recycled in the system. Optionally, the water can be recycled also. The desired lithium carbonate is then separated from the mother liquor (filtrate) which can be returned to the extractor or disposed of.

[0100] Figure 5 depicts yet still another preferred procedure for the production of lithium carbonate. Therein and similar to Figure 1, a LFP feedstock is fed to a furnace, e.g., a rotary kiln or a batch kiln. The LFP feedstock is heated to a predetermined temperature for a predetermined time thereby providing a material feed for an oxidation process (Reactor A).

[0101] Therein Reactor A is further fed an oxidant and water, providing an aqueous slurry with the pyrolyzed LFP. The commixing of the oxidant and the pyrolyzed LFP can oxidize the iron and provide an iron(III) slurry. The iron(III) slurry is then admixed with supercritical CO2 generating an aqueous lithium bicarbonate slurry. The aqueous lithium bicarbonate slurry can then be depressurized and the venting carbon dioxide recovered and recycled for later extractions.

[0102] Herewith, depressurizing the aqueous lithium bicarbonate slurry from Reactor B can include decreasing the pressure on the slurry to about 1 to about 50, about 1 to about 40, about 1 to about 30, about 1 to about 20, about 1 to about 10, or about 1 to about 5 bar. Thereafter, the depressurized-aqueous lithium bicarbonate slurry can be separated into solid residue and a filtrate via a first solid-liquid separation apparatus (Sep. A), e.g., a filter, a centrifuge, or a hydrocyclone. Thereafter the filtrate is added to a crystallizer wherein a concentration of water and / or CO2 is reduced and lithium carbonate is precipitated. The separated CO2 and water can themselves be separated with the CO2 being recycled in the system. As shown, the water can be recycled also. The desired lithium carbonate is then separated from the mother liquor (filtrate) which can be returned to the extractor or disposed of.

[0103] Figure 6 depicts another preferred procedure for the production of lithium carbonate. Therein and similar to Figure 1, a LFP feedstock is fed to a furnace, e.g., a rotary kiln or a batch kiln. The LFP feedstock is heated to a predetermined temperature for a predetermined time thereby providing a material feed for an oxidation reactor.

[0104] Similar to Fig. 5, the pyrolyzed LFP is admixed with an oxidant and water. The commixing of the oxidant and the pyrolyzed LFP can oxidize the iron and provide an iron(III) slurry. Notably, the oxidation reactor is further fed with carbon dioxide, in one example thecarbon dioxide is subcritical, in another example the carbon dioxide is liquid, in still another example the carbon dioxide is gaseous. Thereafter formation of the iron(III) slurry, the carbon dioxide is converted to supercritical CO2 by, for example, increasing the temperature and / or increasing the pressure and the supercritical CO2 generating an aqueous lithium bicarbonate slurry. The aqueous lithium bicarbonate slurry can then be depressurized and the venting carbon dioxide recovered and recycled for later extractions.

[0105] Herewith, depressurizing the aqueous lithium bicarbonate slurry from the scCCh Extractor can include decreasing the pressure on the slurry to about 1 to about 50, about 1 to about 40, about 1 to about 30, about 1 to about 20, about 1 to about 10, or about 1 to about 5 bar. Thereafter, the depressurized-aqueous lithium bicarbonate slurry can be separated into solid residue and a filtrate via a first solid-liquid separation apparatus (Sep. A), e.g., a filter, a centrifuge, or a hydrocyclone. Thereafter the filtrate is added to a crystallizer wherein a concentration of water and / or CO2 is reduced and lithium carbonate is precipitated and separated via a second solid-liquid separation apparatus (Sep. B). The separated CO2 and water can themselves be separated with the CO2 being recycled in the system. As shown, the water can be recycled also. The desired lithium carbonate is then separated from the mother liquor (filtrate) which can be returned to the extractor or disposed of.

[0106] Figure 7 depicts another preferred procedure for the production of lithium carbonate. Therein the process is similar to Figure 1 with the exception that the LFP feedstock is used without pyrolysis. Notably, any of the above preferred procedures for the production of lithium carbonate can utilize non-pyrolized LFP as long as the LFP is free of a surface coating that may prevent the oxidant and / or the carbon dioxide from interacting with the iron and lithium therein.

[0107] While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and / or methods in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain agents that are both chemically and physically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-1. A process comprising: admixing lithium iron phosphate (LFP), an oxidizing agent, carbon dioxide, and water; separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture.

2. The process of claim 1, wherein admixing the LFP, oxidizing agent, carbon dioxide, and water includes: admixing the LFP and the oxidizing agent; and then admixing the carbon dioxide and water with the admixture of LFP and oxidizing agent.

3. The process of claim 2, wherein admixing the LFP and the oxidizing agent further includes admixing the LFP, the oxidizing agent, and water.

4. The process of claim 1, wherein admixing the LFP, oxidizing agent, carbon dioxide, and water includes: admixing the LFP, carbon dioxide, and water; and then admixing the oxidizing agent with the admixture of LFP, carbon dioxide, and water.

5. The process of claim 1, wherein admixing the LFP, oxidizing agent, carbon dioxide, and water includes the contemporaneous admixing of LFP, oxidizing agent, carbon dioxide, and water.

6. The process of claim 1, wherein admixing the LFP, oxidizing agent, carbon dioxide, and water includes admixing an aqueous solution of the LFP with the oxidizing agent; and then admixing therewith carbon dioxide.

7. The process of claim 1, wherein the oxidizing agent is selected from hydrogen peroxide, peroxyacetic acid, oxygen, and / or ozone.

8. The process of claim 7, wherein the oxidizing agent is an aqueous solution of hydrogen peroxide, peroxyacetic acid, oxygen, and / or ozone.

9. The process of claim 8, wherein the oxidizing agent is an aqueous solution of about 3 wt.% to about 60 wt.%, about 3 wt.% to about 45 wt.%, about 3 wt.% to about 30 wt.%, or about 3 wt. % to about 15 wt.% hydrogen peroxide.

10. The process of claim 7, wherein the oxidizing agent includes ozone and the process includes providing oxygen to an ozone generator and thereafter admixing generated ozone with the LFP.

11. The process of claim 10, wherein the ozone generator is a UV generator.

12. The process of claim 1, wherein the LFP, oxidizing agent, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C, about 75 °C to about 250 °C, about 100 °C to about 250 °C, about 100 °C to about 200 °C, or about 100 °C to about 175 °C; and at a pressure of about 80 to about 300 bar, about 80 to about 250 bar, about 80 to about 200 bar, about 80 to about 175 bar, about 80 to about 150 bar, or about 100 to about 150 bar.

13. The process of claim 12, wherein the oxidizing agent is oxygen; and wherein the LFP, oxygen, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300 bar.

14. The process of claim 12, wherein the oxidizing agent is ozone; and wherein the LFP, ozone, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300 bar.

15. The process of claim 12, wherein the oxidizing agent is hydrogen peroxide; and wherein the LFP, hydrogen peroxide, carbon dioxide, and water are admixed at a temperature of about 50 °C to about 250 °C; and at a pressure of about 80 to about 300bar.

16. The process of claim 15, wherein the hydrogen peroxide concentration in the admixture is about 1 wt.% to about 30 wt.%, about 2.5 wt.% to about 30 wt.%, about 5 wt.% to about 30 wt.%, or about 5 wt.% to about 20 wt.%.

17. The process of claim 1, wherein the carbon dioxide is supercritical CO2.

18. The process of claim 1, wherein separating the aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture includes: filtering the admixture and recovering a filtrate which includes the aqueous solution.

19. The process of claim 1, wherein separating the aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture includes: centrifuging the admixture and recovering a filtrate which includes the aqueous solution.

20. The process of claim 1, further comprising crystallizing lithium carbonate from the aqueous solution that includes lithium carbonate and / or lithium bicarbonate.

21. The process of claim 1, further comprising distilling water from the aqueous solution that includes lithium carbonate and / or lithium bicarbonate and precipitating lithium carbonate.

22. The process of claim 1, further comprising providing the LFP by the pyrolysis of a cathodic material.

23. The process of claim 22, wherein the cathodic material is an off-specifi cation lithium iron phosphate cathodic material.

24. The process of claim 22, wherein the pyrolysis of the cathodic material is at a temperature of about 200 to about 800 °C, about 200 to about 700 °C, about 200 toabout 600 °C, about 300 to about 600 °C, or about 400 to about 600 °C.

25. A process comprising: providing to a lithium iron phosphate (LFP) an admixture flux that includes an oxidizing agent, carbon dioxide, and water; and separating an effluent from the LFP that includes lithium carbonate and / or lithium bicarbonate.

26. The process of claim 25, wherein the admixture flux includes supercritical CO2.

27. The process of claim 25, wherein the admixture flux is provided to the LFP at a temperature of about 50 to about 250 °C; and at a pressure of about 80 to about 300 bar.

28. The process of claim 25, wherein the admixture flux is provided to the LFP and the effluent is separated from the LFP as a continuous process.

29. The process of claim 25, wherein the admixture flux fluidizes the LFP thereby commixing the LFP and the admixture flux.

30. A process comprising: commixing lithium iron phosphate (LFP), an oxidizing agent, carbon dioxide, and water for a reaction time of about 5 min to about 12 hours at a reaction temperature of about 50 to about 300 °C and at a reaction pressure of about 80 to about 300 bar; and thereafter separating an aqueous solution that includes lithium carbonate and / or lithium bicarbonate from the admixture.

31. The process of claim 30, wherein commixing the admixture includes engaging a paddle mixer within the admixture.

32. The process of claim 30, wherein commixing the admixture includes sonicating the admixture.

33. The process of claim 30, wherein the admixture includes a LFP to water mass ratio ofabout 1:100, about 1:90, about 1:80, about 1:70, about 1:60, about 1:50, about 1:40, about 1:30, about 1:20, about 1:10, about 1:9, about 1:8, about 1:7, about 1:6, about 1:5, about 1:4, about 1:3, or about 1:

2.

34. The process of claim 30, wherein the admixture includes an oxidizing agent to LFP molar ratio of 10:1 to about 1:1, about 9:1 to about 1:1, about8:l to about 1:1, about7:l to about 1:1, about 6: 1 to about 1:1, about 5: 1 to about 1:1, about 4: 1 to about 1:1, about 3:1 to about 1:1, orabout2:l to about 1:1.

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