DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Status of Claims
Claims 1-17 remain pending in the application; claims 1, 2, 7, and 8 have been amended and claim 17 is newly added.
Response to Amendment
The amendment filed 05/12/2026 has been entered. The amendments to the claims do not overcome the 112(b) rejections made to claims 2 and 7 individually; these rejections are therefore withdrawn.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-17 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 1 recites the limitation "mixing the filtrate... with the lithium iron phosphate waste" in step (4). The lithium iron phosphate (LiFePO4) waste recited earlier in claim 1 is transformed in identity through steps (2) to (4), first transforming into a slurry, then a filtrate/slag product, then another filtrate. Step (4) requires mixing the filtrate from step (3) with the original LiFePO4 waste, which renders unclear the interaction between the filtrate with the LiFePO4 waste, as it is unclear whether the filtrate should be mixed with the LiFePO4 waste-containing slurry of step (1) or if the filtrate is mixed with a second LiFePO4 waste, since the LiFePO4 waste of step (1) is mixed with water immediately, in the instant claim.
Claim 1 has been amended to additionally recite “(4) mixing the filtrate containing Li+, Fe3+, with the lithium iron phosphate waste to obtain a mixture, and subjecting the mixture to a multi-stage counter-current circulation leaching process to obtain a lithium solution; wherein the multi-stage counter-current circulation leaching process comprises mixing the filtrate containing Li+, Fe3+ with the lithium iron phosphate waste…”. Since step (4) already begins with a mixing of filtrate with LFP waste before subjecting the mixture to leaching, it is unclear if the multi-stage counter-current circulation leaching is to comprise an additional step of mixing the filtrate with LFP waste: if so, which filtrate containing Li+, Fe3+ would be an additional filtrate containing Li+, Fe3+? And what waste would be considered that additional amount of waste? Claim 1 is therefore indefinite in the scope of to what material the filtrate of step (4) should be added. Claims 2-17 depend on, or otherwise incorporate the limitations of, claim 1 and do not rectify the issue of indefiniteness, and are therefore similarly rejected.
Response to Arguments
Applicant's arguments filed on 5/12/2026 regarding the rejections made under U.S.C. 112 have been fully considered but they are not persuasive. The amendments made to claim 1 do not rectify the issue of a lack of clarity as to what the filtrate of step (4) is to be combined with. Applicant notes that the filtrate contains water and therefore there is no need to repeat the process that adding water to obtain a lithium iron phosphate slurry, and steps (2)-(3) can be performed directly. It remains unclear as to whether the filtrate is added to the LFP waste before addition of water, support for which is found in the figure, or if the filtrate is added to the LFP waste in place of the water addition of step (1), for the multi-stage counter-current leaching, or if the filtrate is added to a slurry of LFP waste with water, to directly repeat steps (2) and (3) as argued on Remarks page 6. Since these alternative interpretations impart mutually exclusive structures to the claimed method, the claim cannot be considered definite in scope.
Applicant’s arguments filed 5/12/2026 regarding to the rejections under U.S.C. 103 have been fully considered, and the arguments regarding the recycling of both Li+ and Fe3+ not found in the prior art, and regarding the countercurrent leaching containing Li+, are persuasive. The rejections of claims 1-16 have been withdrawn.
Applicant asserts (Remarks p. 10) that the second filtrate of Dai contains only unreacted Li+. This argument is found convincing, since Dai teaches that the Fe3+ is predominantly precipitated into Fe(OH)3 (0045). While Dai teaches that the Fe3+ contained in the hydroxide does also participate in the recycling/circulation process by being redissolved (0013, 0061 step 3) and teaches that Fe3+ participates in the circulation process by being supplemented to the third filtrate being sent back to step 1 (0011, 0061), Dai does not teach that the redissolution of the hydroxide contains lithium to be recycled.
Applicant asserts that the subject matter of Xu is a multi-stage countercurrent solid-liquid contact device, whereas the present disclosure focuses more on the circulation mechanism between materials. This argument is found convincing, and the previous rejections are withdrawn.
Applicant asserts on Remarks page 11 that the prior art does not teach mixing the filtrate containing Li+ and Fe3+ with LPF waste for multi-stage countercurrent leaching. This argument is found convincing, since Dai does not motivate one skilled in the art to optimize the process of Dai towards obtaining lithium in solution, and therefore does not teach a motivation to subject Li+ in solution to a multi-stage counter-current circulation leaching as instantly claimed. Such motivation can similarly not be found in the prior art. Therefore the previous rejections are withdrawn.
The examiner notes that page 13 of Remarks summarizes that claim 17 is newly added with a scope of 5-10 cycles; the present claim 17 claims 10-15 cycles. It is interpreted that page 13 of Remarks is a typographic error that should similarly read 10-15 cycles.
Allowable Subject Matter
Claims 1-17 are subject to rejections under U.S.C. 112 as discussed above. Claims 1-17 contain subject matter that is allowable over the prior art.
The closest prior art is considered to be Dai, CN 110474123 A, as cited herein and in the previous Office action, and Dai et al. 2020, Theoretical-molar Fe3+ recovering lithium from spent LiFePO4 batteries: an acid-free, efficient, and selective process, Journal of Hazardous Materials, Volume 396, 5 September 2020, 122707. Dai teaches a method for recovering lithium from lithium iron phosphate waste (0060) comprising adding waste LiFePO4 battery cathode material to a trivalent iron salt in solution form (step 1, 0032), such a solution necessarily containing water. Dai further teaches filtering a resulting product to obtain an iron phosphate slag and a filtrate (0032) containing Li+, Fe2+ (0037) ; (3) adding an oxidizing agent to the filtrate containing Li+, Fe2+ to perform a reaction, and filtering to obtain iron hydroxide and a filtrate containing Li+,Fe3+ (step 2, 0044, 0045, filtered, 0051). Dai teaches a molar amount of iron in the soluble iron salt in step (2) is 1 : 1 to a molar amount of iron in the lithium iron phosphate slurry (0038). Dai teaches that the method is a circulation process (closed-loop circulation system, 0024) wherein the ferric ions obtained are recirculated to the step 1 of adding waste LFP material into the trivalent iron salt solution (0013).
Dai does not teach that the second filtrate (corresponding to the filtrate containing Li+, Fe3+ of the present claim) still contains Fe3+, and does not teach that the second filtrate is mixed with LFP waste to obtain a mixture and subjecting the mixture to multi-stage countercurrent leaching for 3-15 cycles, where the countercurrent leaching comprises repeating steps (2) and (3) to obtain the lithium solution.
Dai specifically teaches that lithium is isolated in the solid carbonate form, and is therefore not circulated in the third filtrate that is circulated (0011).
Dai further does not teach that the multi-stage countercurrent leaching process of repeating steps (2) and (3) is performed for 3-15 cycles.
Although it is known in the prior art to perform multi-stage countercurrent circulation leaching (Xu) to purify lithium solution, Dai does not provide motivation to implement such methods in the disclosed invention, since Dai teaches a solid lithium product. Dai further only teaches the circulation of Fe3+ ions, and does not teach the circulation of Li+ ions.
Non-patent literature Dai similarly does not teach the circulation of lithium ions, and further does not teach the circulation of ferric ions without addition of acid or alkali. Figure 1 of non-patent literature Dai is provided below for clarity, wherein it is shown that sulfuric acid and sodium hydroxide are both required, and the ferric ion is not recirculated with lithium ion.
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Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Non-patent literature Dai et al. 2020, Theoretical-molar Fe3+ recovering lithium from spent LiFePO4 batteries: an acid-free, efficient, and selective process, Journal of Hazardous Materials, Volume 396, 5 September 2020, 122707 teaches a method of leaching LFP powder (Section 2.2.2.) wherein the powder is leached with ferric salt and persulfate in the same step, followed by obtaining FePO4 and Fe2(SO4)3 without the addition of acid, which can be recycled (Figure 2). The equivalence of FeCl3 and MSO4 (M = Fe, Cu, Ni, Mg) with the leaching materials of Figures 1 and 2 is further taught (Section 2.2.3.).
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Eileen Moudou whose telephone number is (571)272-1768. The examiner can normally be reached M-Th 8 AM - 4 PM EST.
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/Eileen Moudou/Examiner, Art Unit 1738
/MICHAEL FORREST/Primary Examiner, Art Unit 1738
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