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 .
Response to Amendment
The amendment filed 02/03/2026 has been entered. Claims 1-7 and 9-20 are pending in this application and examined herein. Claims 18-20 are withdrawn. Claims 1, 5-6, and 10 are amended. Claim 8 is cancelled.
The rejections under 35 USC 112(b) to claims 5-6, 10-12, and 14-15 are withdrawn in view of the amendments to claims 5, 6, and 10, and Applicant’s arguments regarding claims 14 and 15.
Drawings
The drawings were received on 02/03/2026. These drawings are acceptable.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-7 and 9-17 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 1 recites “wherein the at least one stripping stage utilizes a stripping solution comprising a dilute acid” in lines 11-12. The instant specification discloses wherein the stripping stage(s) utilize a stripping solution comprising dilute nitric acid specifically (e.g., instant specification: [0069, 0108]), however the instant specification does not disclose using dilute acids generally (i.e., that any dilute acid including those which are not nitric acid are used), and therefore does not describe the claimed invention in a manner understandable to a person of ordinary skill in the art in a way that shows that the inventor invented the claimed invention at the time of filing.
Claims dependent upon claims rejected above, either directly or indirectly, are likewise rejected under this statute.
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 1-7 and 9-17 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.
A broad range or limitation together with a narrow range or limitation that falls within the broad range or limitation (in the same claim) may be considered indefinite if the resulting claim does not clearly set forth the metes and bounds of the patent protection desired. See MPEP § 2173.05(c). In the present instance, claim 1 recites the broad recitation "in at least one stripping stage" in line 8 and “the at least one stripping stage” in line 11, and the claim also recites “in at least six stripping stages” in line 10 which is the narrower statement of the range/limitation. The claim(s) are considered indefinite because there is a question or doubt as to whether the feature introduced by such narrower language is (a) merely exemplary of the remainder of the claim, and therefore not required, or (b) a required feature of the claims.
The term “dilute acid” in claim 1 is a relative term which renders the claim indefinite. The term “dilute acid” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention, making unclear which concentration(s) of acid are claimed.
Claims dependent upon claims rejected above, either directly or indirectly, are likewise rejected under this statute.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-2, 4-7, 9-10, and 13-15 are rejected under 35 U.S.C. 103 as being unpatentable over Kuzmin (RU 2293134 C1, supplied with IDS filed 12/29/2022, complete machine translation supplied with restriction requirement dated 07/23/2025) in view of Das (“Thermo-economic analysis of supercritical extraction of rare earth elements from coal ash”, supplied with restriction requirement dated 07/23/2025), and Liao et al. (US 20170267540 A1).
Regarding claims 1 and 9, Kuzmin teaches a method of extracting rare earth metals and yttrium from coals and ash and slag waste from their combustion (i.e., a process for obtaining at least one rare earth element from a coal-based resource) (Title), the process comprising forming a mixture comprising tributyl phosphate (i.e., an extractant complex) and a coal-based resource comprising at least one rare earth element [0013], and recovering the at least one rare earth element by re-extraction of metal salts in water (i.e., in at least one stripping stage) [0014]. Kuzmin teaches wherein the process step of recovering the at least one rare earth element in a number of re-extraction stages (i.e., stripping stages) [0027] may include any number of stripping stages [0027], which would include the claimed numbers of stripping stages.
Kuzmin does not teach extracting the at least on rare earth element from the mixture in the presence of a supercritical fluid.
Das discusses extraction of rare earth elements from coal ash using supercritical CO2 (Title, Abstract), where supercritical fluid extraction is performed with tributyl phosphate (Abstract, 2. Literature review: paragraph 1, 3.1. Process configuration and analytical approaches: paragraphs 1-2). Das teaches supercritical CO2 is a popular solvent as CO2 upon depressurization turns into non-hazardous CO2 gas, is readily available in high purity and is inexpensive to purchase, and is environmentally benign (1.1. Coal ash as a source of rare earths: paragraph 6). Therefore, it would have been obvious to have use supercritical carbon dioxide as an extraction solvent during the extraction of rare earth from coal-bearing material of Kuzmin, as doing so would benefit from readily available and inexpensive reagents which are environmentally benign and non-hazardous as taught by Das.
Kuzmin in view of Das teaches stripping the rare earth element by utilizing a stripping solution (Kuzmin: [0027]). Kuzmin in view of Das does not teach wherein the stripping solution comprises a dilute acid.
Liao teaches the use of amino-containing neutral phosphine extractant in extraction and separation of thorium (i.e., a rare earth element) (Title), where thorium is solvent extracted using an extractant [0012], where the extractant may comprise an auxiliary extractant [0039], which may be tri-butyl-phosphate (TBP) [0045], and where a thorium-loaded organic phase is stripped with a stripping agent [0056], thus Liao and Kuzmin are analogous to the instant application as both are directed to obtaining rare earth element by extraction with an extractant complex and recovery by stripping. Liao teaches the stripping of rare earth element comprises utilizing a stripping solution comprising a solution of nitric acid, hydrochloric acid, or sulfuric acid [0056], preferably a diluted nitric acid solution [0056]. Liao teaches products with purities of 99.99% (Examples 1-2), 99.95% (Example 3), 99.9% (Example 6) and 99.999% (Example 9) are recovered using nitric acid stripping solution.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have used a dilute nitric acid stripping solution as taught by Liao as the stripping solution of Kuzmin as doing so is associated with products of 99.9% or greater purity in Liao.
Further, it has long been held that it is prima facie obvious to substitute equivalents taught by the prior art to be useful for the same purpose. See MPEP 2144.06 (II). As in the instant case Kuzmin in view of Das only differs from claim 1 in that the instant claim uses a stripping solution comprising a dilute acid to recover REE, while Kuzmin in view of Das uses a stripping solution consisting of water to recover REE, and Liao uses a stripping solution comprising dilute acid to recover REE, a prima facie case of obviousness exists as it would have been obvious to have substituted the dilute nitric acid solution of Liao into the method of modified Kuzmin to perform stripping.
Regarding claim 5, Kuzmin teaches wherein the extractant complex is TBP-HNO3 [0014].
Regarding claim 6, Das teaches wherein the supercritical fluid is supercritical CO2 (1.1. Coal ash as a source of rare earths: paragraph 6).
Claims 2, 4, 7, 10, and 13-15 remain rejected as set forth in the Office Action dated 11/04/2025. Claims 2, 4, 7, and 13-15 have not been amended since that time, and claim 10 has not been amended since that time, therefore, the previously presented grounds of rejection set forth how the prior art teaches or suggests all of the limitations of the claims.
Claim 3 is rejected under 35 U.S.C. 103 as being unpatentable over Kuzmin in view of Das and Liao as applied to claim 1 above, further in view of Wang et al. (“Rare earth elements and yttrium in coal ash from the Luzhou power plant in Sichuan, Southwest China: Concentration, characterization and optimized extraction”, supplied with Office Action dated 11/04/2025) with evidence from Belli et al. (“Search for α decay of natural Europium”, supplied with Office Action dated 11/04/2025).
Claim 3 remains rejected as set forth in the Office Action dated 11/04/2025. Claim 3 has not been amended since that time, therefore, the previously presented grounds of rejection set forth how the prior art teaches or suggests all of the limitations of the claim.
Claim 11 is rejected under 35 U.S.C. 103 as being unpatentable over Kuzmin in view of Das and Liao as applied to claim 10 above, further in view of Nechaev et al. (RU 2685833 C1, original document supplied with IDS filed 12/29/2022, machine translation supplied with Office Action dated 11/04/2025).
Claim 11 remains rejected as set forth in the Office Action dated 11/04/2025. Claim 11 has not been amended since that time, therefore, the previously presented grounds of rejection set forth how the prior art teaches or suggests all of the limitations of the claim.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Kuzmin in view of Das and Liao as applied to claim 10 above, further in view of Sugita et al. (US 20140283652 A1, cited in Office Action dated 11/04/2025).
Claim 12 remains rejected as set forth in the Office Action dated 11/04/2025. Claim 12 has not been amended since that time, therefore, the previously presented grounds of rejection set forth how the prior art teaches or suggests all of the limitations of the claim.
Claims 16-17 and are rejected under 35 U.S.C. 103 as being unpatentable over Kuzmin in view of Das and Liao as applied to claim 1 above, further in view of Laudal et al. (US 20180265948 A1, cited in Office Action dated 11/04/2025).
Claims 16-17 remain rejected as set forth in the Office Action dated 11/04/2025. Claims 16-17 have not been amended since that time, therefore, the previously presented grounds of rejection set forth how the prior art teaches or suggests all of the limitations of the claims.
Response to Arguments
Applicant’s arguments, see pg. 6-7 of remarks, filed 02/03/2026, with respect to the rejections of claims 1-17 under Kuzmin in view of Das have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new grounds of rejection is made in view of Liao et al. (US 20170267540 A1), which teaches using diluted acid to perform stripping.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). 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.
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/Keith D. Hendricks/Supervisory Patent Examiner, Art Unit 1733
/NIKOLAS TAKUYA PULLEN/Examiner, Art Unit 1733
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