Prosecution Insights
Last updated: April 19, 2026
Application No. 18/453,728

METHOD FOR RECYCLING HYDROPHOBIC DEEP EUTECTIC SOLVENT AND NICKEL LEACHING METHOD

Non-Final OA §103§112
Filed
Aug 22, 2023
Examiner
SIMKINS, SLONE ELIZABETH
Art Unit
1735
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Toyota Jidosha Kabushiki Kaisha
OA Round
1 (Non-Final)
74%
Grant Probability
Favorable
1-2
OA Rounds
3y 3m
To Grant
99%
With Interview

Examiner Intelligence

Grants 74% — above average
74%
Career Allow Rate
14 granted / 19 resolved
+8.7% vs TC avg
Strong +29% interview lift
Without
With
+29.4%
Interview Lift
resolved cases with interview
Typical timeline
3y 3m
Avg Prosecution
41 currently pending
Career history
60
Total Applications
across all art units

Statute-Specific Performance

§101
2.0%
-38.0% vs TC avg
§103
45.5%
+5.5% vs TC avg
§102
15.5%
-24.5% vs TC avg
§112
35.4%
-4.6% vs TC avg
Black line = Tech Center average estimate • Based on career data from 19 resolved cases

Office Action

§103 §112
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 . Information Disclosure Statement The Information Disclosure Statements filed 22 August 2023 and 29 April 2024 have been considered. 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 1-4 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, line 1, recites "a method for recycling a hydrophobic deep eutectic solvent". However, it is unclear where within the method of claim 1 the hydrophobic deep eutectic solvent is recycled, as lines 5-6, recite "bringing the hydrophobic deep eutectic solvent and hydrochloric acid into contact with each other" with no additional steps. This limitation is interpreted as requiring producing a recycled hydrophobic eutectic solvent after bringing the hydrophobic deep eutectic solvent and hydrochloric acid into contact with each other. It is further unclear how the recycled hydrophobic deep eutectic solvent is formed as a result of contacting a used deep eutectic solvent with hydrochloric acid. Claim 1, line 3, recites "preparing a hydrophobic deep eutectic solvent used for leaching a metal element". It is unclear if the limitation of a “solvent used for leaching a metal element” is the intended use of the hydrophobic deep eutectic solvent, or if this limitation requires using hydrophobic deep eutectic solvent to leach a metal element. This limitation is interpreted as requiring using a hydrophobic deep eutectic solvent for leaching a metal element, and bringing the used hydrophobic deep eutectic solvent into contact with hydrochloric acid. Claim 1, lines 6-8, recite "wherein in the hydrophobic deep eutectic solvent, a hydrogen bond donor is a carboxy group-containing compound, and a hydrogen bond acceptor is chloride salt". It is unclear what the relationship is between the hydrophobic deep eutectic solvent and the hydrogen bond donor and the hydrogen bond acceptor. The limitation is interpreted as requiring the hydrophobic deep eutectic solvent is a mixture including a hydrogen bond donor and a hydrogen bond acceptor (per [0019] of the Specification). Claim 4, line 1, recites “a nickel leaching method”. However, it is unclear where in the method of claim 4 nickel is leached, as lines 4-5 recite “bringing the recycled hydrophobic deep eutectic solvent and a nickel ore into contact with each other” with no additional steps. This limitation is interpreted as requiring leaching nickel from a nickel ore bringing the recycled hydrophobic deep eutectic solvent and a nickel ore into contact with each other. Claims 2-3 are indefinite as they depend from an indefinite base and fail to cure the deficiencies of the base claim. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. 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. Claims 1-3 are rejected under 35 U.S.C. 103 as being unpatentable over Zhang (CN 114645144) in view of Batal (WO 2023191737) and Siriwardana (CN 110392742). Regarding Claim 1, Zhang discloses a method for recycling a deep eutectic solvent (DES) [n0023]. Zhang further discloses extracting lithium from a lithium-containing solution using a deep eutectic solvent (DES used for extracting lithium meets the limitation of a DES used for leaching a metal element; [n0009], [n0011]). Zhang further discloses the DES after extraction has a low water solubility [n0023], such that the DES of Zhang meets the limitation of hydrophobic. Zhang further discloses the lithium-loaded deep eutectic solvent and a stripping agent were mixed for stripping, and after stripping equilibrium, phase separation was performed to obtain a lithium-rich solution and an empty-loaded deep eutectic solvent (empty-loaded DES meets the limitation of a recycled DES; [n0059]), wherein the stripping agent is hydrochloric acid (mixing the lithium-loaded DES and the hydrochloric acid stripping agent meets the limitation of bring the hydrophobic DES and hydrochloric acid into contact with each other; [n0060]). Zhang further discloses the empty-loaded deep eutectic solvent obtained after back-extraction can be recycled without generating any waste [n0066]. Zhang further discloses the deep eutectic solvent comprises a hydrogen bond donor and a hydrogen bond acceptor [n0010]. Zhang further discloses preferably, the hydrogen bond donor is selected from at least one of benzoyltrifluoroacetone, thiophenecarboxylic acid trifluoroacetone (thiophenecarboxylic acid trifluoroacetone meets the limitation of a carboxy-group containing compound), dibenzoylmethane, naphthoyltrifluoroacetone, and phenylmethylformylpyrazolone [n0014]. Zhang further discloses the lithium-loaded deep eutectic solvent and a stripping agent were mixed by shaking at a volume ratio of (0.5-20):1 for stripping [n0059], the stripping agent is hydrochloric acid with a concentration of 0.05 mol/L to 6 mol/L [n0060], and the hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) are mixed in a molar ratio of 1:2, 1:1 or 2:1 in the preparation of the DES [n0010]. Therefore, the ranges provided in Zhang for the ratio of DES to HCl, the concentration of HCl, and the ratio of HBD to HBA, results in an amount of hydrochloric acid used in Zhang which overlaps or, in the alternative, is close to the claimed range of 1 mole or more of hydrogen chloride with respect to 1 mole of the hydrogen bond acceptor such that the range taught by Zhang obviates the claimed range. See MPEP 2144.05 (I). Additionally, regarding the amount of hydrochloric acid in claim 1, discovery of optimum ranges of a result effective variable in a known process is ordinarily within the skill of art and selection of the optimum ranges within the general condition is obvious (MPEP 2144.05 (II)). Zhang is silent to leaching the lithium metal from an ore using the deep eutectic solvent. Zhang, however, discloses lithium resources are mainly found in lithium-bearing ores [n0002]. Zhang further discloses extracting lithium from a lithium-containing solution using a deep eutectic solvent ([n0009], [n0011]), wherein the lithium-containing solution is the lithium precipitation mother liquor separated after preparing lithium carbonate by precipitation method [n0019], and the main process for producing lithium carbonate from lithium ore includes acid leaching, alkali leaching, and salt phase inversion [n0003]. Batal discloses leaching zinc and lead (zinc and lead meet the limitation of a metal element) from Zn-Pb ores using a deep eutectic solvent (Abstract). Batal further discloses leaching metal from ores, using a DES, reduces acid consumption in the acid leaching process (pg. 5, lines 15-17) and does not require extra process steps for removing metals from leaching solutions (pg. 5, lines 22-24). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Zhang to incorporate the teachings of Batal to leach a metal element from an ore containing the metal element as the lithium-containing solution of Zhang is derived from ores [n0002]-[n0003], and leaching metals from ores directly, using a DES, reduces acid consumption in the acid leaching process (pg. 5, lines 15-17) and does not require extra process steps for removing metals from leaching solutions (pg. 5, lines 22-24), as recognized by Batal. Zhang is further silent to the hydrogen bond acceptor being a chloride salt. Siriwardana discloses extraction of rare earth elements (rare earth elements meet the limitation of a metal element) in metallic or alloy form using a deep eutectic solvent [0013]. Siriwardana further discloses rare earth elements exist in ores [0008]. Siriwardana further discloses the hydrogen bond donor is selected from C1-C18 carboxylic acids (carboxylic acids meet the limitation of a carboxy group-containing compound) [0027], and the hydrogen bond acceptor is a salt of the formula Cat+X- [0039], wherein the cation (Cat+) may be a quaternary ammonium cation [0040] and the anion in the salt formula may be a halide, particularly Cl- (quaternary ammonium chloride meets the limitation of a chloride salt; [0053]). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Zhang to incorporate the teachings of Siriwardana to use a DES with a chloride salt hydrogen bond acceptor, because a chloride salt hydrogen bond acceptor is a process parameter well-known in the art of using DES for leaching metal elements. Regarding Claim 2, Zhang discloses the lithium-loaded deep eutectic solvent and a stripping agent were mixed by shaking at a volume ratio of (0.5-20):1 for stripping [n0059], the stripping agent is hydrochloric acid with a concentration of 0.05 mol/L to 6 mol/L [n0060], and the hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) are mixed in a molar ratio of 1:2, 1:1 or 2:1 in the preparation of the DES [n0010]. Therefore, the ranges provided in Zhang for the ratio of DES to HCl, the concentration of HCl, and the ratio of HBD to HBA, results in an amount of hydrochloric acid used in Zhang which overlaps or, in the alternative, is close to the claimed range of 2 moles or more of hydrogen chloride with respect to 1 mole of the hydrogen bond acceptor such that the range taught by Zhang obviates the claimed range. See MPEP 2144.05 (I). Additionally, regarding the amount of hydrochloric acid in claim 1, discovery of optimum ranges of a result effective variable in a known process is ordinarily within the skill of art and selection of the optimum ranges within the general condition is obvious (MPEP 2144.05 (II)). Regarding Claim 3, Zhang discloses the deep eutectic solvent comprises a hydrogen bond donor and a hydrogen bond acceptor [n0010]. Zhang further discloses the hydrogen bond donor may be thiophenecarboxylic acid trifluoroacetone (thiophenecarboxylic acid trifluoroacetone meets the limitation of a carboxy-group containing compound) [n0014]. Zhang is silent to the hydrogen bond donor being a fatty acid, and the hydrogen bond acceptor being a quaternary ammonium chloride. Siriwardana discloses extraction of rare earth elements (rare earth elements meet the limitation of a metal element) in metallic or alloy form using a deep eutectic solvent [0013]. Siriwardana further discloses rare earth elements exist in ores [0008]. Siriwardana further discloses the hydrogen bond donor is selected from C1-C18 carboxylic acids (C12-C18 carboxylic acids are fatty acids) [0027], and the hydrogen bond acceptor is a salt of the formula Cat+X- [0039], wherein the cation (Cat+) may be a quaternary ammonium cation [0040] and the anion in the salt formula may be a halide, particularly Cl- (a salt with a quaternary ammonium cation and chloride anions meets the limitation of a quaternary ammonium chloride; [0053]). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Zhang to incorporate the teachings of Siriwardana to use a DES with a fatty acid hydrogen bond donor and a quaternary ammonium chloride hydrogen bond acceptor, because fatty acid hydrogen bond donors and quaternary ammonium chloride hydrogen bond acceptors are process parameters well-known in the art of using DES for leaching metal elements. Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Zhang (CN 114645144) in view of Batal (WO 2023191737) and Siriwardana (CN 110392742) and Kujawa (US 2024/0084416). Regarding Claim 4, Zhang, Batal, and Siriwardana teach the elements as described above with regards to claim 1. Zhang discloses the empty-loaded deep eutectic solvent obtained after back-extraction can be recycled without generating any waste [n0066], such that Zhang meets the limitation of bringing the recycled hydrophobic deep eutectic solvent and the lithium-containing solution into contact with each other. Zhang further discloses lithium resources are mainly found in lithium-bearing ores [n0002]. Zhang further discloses extracting lithium from a lithium-containing solution using a deep eutectic solvent ([n0009], [n0011]), wherein the lithium-containing solution is the lithium precipitation mother liquor separated after preparing lithium carbonate by precipitation method [n0019], and the main process for producing lithium carbonate from lithium ore includes acid leaching, alkali leaching, and salt phase inversion [n0003]. Zhang is silent to leaching a metal element from ore using the DES. Batal discloses leaching zinc and lead (zinc and lead meet the limitation of a metal element) from Zn-Pb ores using a deep eutectic solvent (Abstract). Batal further discloses leaching metal from ores, using a DES, reduces acid consumption in the acid leaching process (pg. 5, lines 15-17) and does not require extra process steps for removing metals from leaching solutions (pg. 5, lines 22-24). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Zhang to incorporate the teachings of Batal to leach a metal element from an ore containing the metal element as the lithium-containing solution of Zhang is derived from ores [n0002]-[n0003], and leaching metals from ores directly, using a DES, reduces acid consumption in the acid leaching process (pg. 5, lines 15-17) and does not require extra process steps for removing metals from leaching solutions (pg. 5, lines 22-24), as recognized by Batal. Zhang is further silent to the metal element being nickel. Kujawa discloses recovering one or more metals or salts thereof from rock, ore, waste materials, etc. by leaching comminuted or crushed feed materials with a leach reagent, wherein the metals include lithium, nickel, lead, etc. [0002]. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Zhang to incorporate the teachings of Batal and Kujawa to leach nickel from a nickel ore by brining the recycled hydrophobic deep eutectic solvent and a nickel ore into contact with each other, because Zhang in view of Batal and Siriwardana teach the claimed invention except that lithium, zinc, or lead is used instead of nickel. Kujawa teaches that the lithium, lead, and nickel are equivalent products known in the art of leaching metal elements. Therefore, because the two products were art recognized equivalents at the time the invention was made, one of ordinary skill in the art would have found it obvious to substitute the lithium or lead for the nickel. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to SLONE ELZABETH SIMKINS whose telephone number is (571)272-3214. The examiner can normally be reached Monday - Friday 8:30AM-4:30PM. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, KEITH WALKER can be reached at (571)272-3458. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /S.E.S./Examiner, Art Unit 1735 /PAUL A WARTALOWICZ/Primary Examiner, Art Unit 1735
Read full office action

Prosecution Timeline

Aug 22, 2023
Application Filed
Jan 27, 2026
Non-Final Rejection — §103, §112 (current)

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Prosecution Projections

1-2
Expected OA Rounds
74%
Grant Probability
99%
With Interview (+29.4%)
3y 3m
Median Time to Grant
Low
PTA Risk
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