Office Action Predictor
Last updated: April 15, 2026
Application No. 18/025,292

Weak Acid Lixiviants for Recovery of Alkaline Earth Metals

Non-Final OA §103§112
Filed
Mar 08, 2023
Examiner
BAUM, ZACHARY JOHN
Art Unit
1736
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Lixivia, INC.
OA Round
1 (Non-Final)
79%
Grant Probability
Favorable
1-2
OA Rounds
2y 11m
To Grant
93%
With Interview

Examiner Intelligence

Grants 79% — above average
79%
Career Allow Rate
86 granted / 109 resolved
+13.9% vs TC avg
Moderate +14% lift
Without
With
+14.0%
Interview Lift
resolved cases with interview
Typical timeline
2y 11m
Avg Prosecution
26 currently pending
Career history
135
Total Applications
across all art units

Statute-Specific Performance

§103
41.4%
+1.4% vs TC avg
§102
20.9%
-19.1% vs TC avg
§112
28.5%
-11.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 109 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 . Claim Objections Claim 1 is objected to because of the following informalities: In line 1, after “comprising”, the semicolon (“;”) should be a colon (“:”). Appropriate correction is required. Claim Interpretation Claim 11 recites “a weak acid lixiviant” and “the regenerated weak acid lixiviant”. As best understood by the Examiner, “regenerate[d]” is used in the sense of “to bring into renewed existence; to reproduce; to generate again” (Oxford English Dictionary, “regenerate (v.), sense 3.a,” 2025). Therefore, “the regenerated weak acid lixiviant” is interpreted to be the same chemical species as “a weak acid lixiviant”. Claim 12 recites the limitation “wherein the weak acid is a weaker acid than carbonic acid”. In Paragraph [0019], the instant Specification states, “The weak acid can be a weaker acid than carbonic acid, and in some embodiments is a weak organic acid (e.g., lactic acid, malic acid. and/or acetic acid).” In Paragraph [0027], the instant Specification states, “In some embodiments the non-amine containing weak organic acid can have a pKa that is less than that of carbonic acid (i.e. less than 6.36),” and in Paragraph [0028] cites weak organic acids having a pKa that is less than 6.36. For clarity and consistently with usage in the chemical arts, organic acids having a lower pKa than carbonic acid are considered to be stronger acids than carbonic acid, and organic acids having a higher pKa than carbonic acid are considered to be weaker acids than carbonic acid (Tissue, Basics of Analytical Chemistry and Chemical Equilibria – A Quantitative Approach (2nd Edition), 2023, Page 202, Paragraph 3 and Table 5.6). 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 11-12 and 15-21 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 11 recites the limitation "the regenerated weak acid lixiviant" in lines 7 and 8 of the claim. There is insufficient antecedent basis for this limitation in the claim. The claim previously recites the limitation “a regenerated weak organic acid lixiviant” (emphasis added) in line 6. This makes it unclear whether the claim requires “the regenerated weak acid lixiviant” to be organic and whether “a weak acid lixiviant” is therefore also required to be organic. As claim 13 further recites that the weak acid is a weak organic acid, the Examiner assumes that claim 11 does not require the regenerated weak acid lixiviant to be an organic acid, as individual claims are given their broadest reasonable interpretation in light of the specification. See MPEP § 2111. Claims 12 and 15-21 are indefinite due to their dependence on the indefinite claim 11 and because they do not cure the indefiniteness of “the regenerated weak acid lixiviant” as it appears in claim 11. As claims 13-14 resolve this indefiniteness by specifying that the weak acid is a weak organic acid, they are not rejected under 35 U.S.C. 112(b)/2nd Paragraph. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. 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 11, 13-15 and 20-21 are rejected under 35 U.S.C. 103 as being unpatentable over Kotiranta (WO 2017/162901 A1). Regarding claim 11, Kotiranta teaches a method for the recovery of an alkaline earth from a raw material (Kotiranta, Page 3, line 10 – Page 10, line 20 and Page 11, lines 12-19) comprising: providing a raw material comprising an alkaline earth (Kotiranta, Page 3, lines 12-27, calcium rich iron containing material) to a reactor (Kotiranta, Page 6, lines 20-23, leaching vessel); in the same reactor, exposing the raw material to a lixiviant (Kotiranta, Page 4, line 6, leaching) to generate an extracted raw material (Kotiranta, Page 4, lines 6-7, calcium-depleted LD slag), a solubilized alkaline earth (Kotiranta, Page 4, line 6, “leaching calcium” implies that calcium is solubilized) and a spent lixiviant (Kotiranta, Page 6, line 32 – Page 7, line 3, obtaining a “regenerated calcium poor leaching solution” as a result of bubbling carbon dioxide implies that the leaching solution (lixiviant) was spent prior to the regeneration); contacting the solubilized alkaline earth and the spent lixiviant with a precipitant (Kotiranta, Page 6, line 32 – Page 7, line 3, carbon dioxide), thereby generating an alkaline earth precipitate (Kotiranta, Page 7, line 1, calcium carbonate) and a regenerated lixiviant (Kotiranta, Page 7, line 3, regenerated calcium poor leaching solution); and separating the alkaline earth precipitate from the regenerated lixiviant (Kotiranta, Page 7, lines 1-2, “thus to remove calcium from said calcium rich leaching solution to obtain a regenerated calcium poor leaching solution”); and returning at least a portion of the regenerated lixiviant to the reactor (Kotiranta, Page 7, lines 3-4, “Said regenerated calcium poor leaching solution may then be (e) recycled to stage (a) or (i), respectively.”), wherein the weak acid lixiviant does not include an amine (Kotiranta, Page 5, lines 9-17, none of the listed lixiviants are amines). Kotiranta does not explicitly teach that the lixiviant is a weak acid lixiviant. However, Kotiranta teaches that acetic acid and ammonium chloride are each a suitable materials to use as lixiviants (Kotiranta, Page 5, lines 11 and 13). It would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to have selected acetic acid, a weak acid, as the lixiviant in Kotiranta’s method. The selection of a known material, which is based upon its suitability for the intended use, is within the ambit of one of ordinary skill in the art. See In re Leshin, 125 USPQ 416 (CCPA 1960), Sinclair & Carroll Co. v. Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945), and MPEP § 2144.07. Because Kotiranta teaches that acetic acid and ammonium chloride are suitable as lixiviants (Kotiranta, Page 5, lines 11 and 13), they would each be obvious to use, and as acetic acid and ammonium are weak acids, a weak acid would correspondingly be obvious. Regarding claims 13-14, Kotiranta renders the method of claim 11 obvious, as discussed above, wherein the weak acid is acetic acid (Kotiranta, Page 5, line 11). Regarding claim 15, Kotiranta renders the method of claim 11 obvious, as discussed above, wherein the extracted raw material is separated from a liquid phase containing the solubilized alkaline earth and the spent lixiviant prior to contacting with the precipitant (Kotiranta, Figure 1, Page 4, lines 18-21, calcium depleted material 13 and calcium rich leaching solution 9 are each obtained, implying that they have been separated.; Page 4, lines 26-31, “The calcium rich leaching solution 9 obtained from the calcium removal stage 1 is subjected to calcium precipitation 2 by feeding a carbon dioxide containing gas 11 into the calcium rich leaching solution to precipitate calcium carbonate (CaCos)[sic] 12…”). Regarding claim 20, Kotiranta renders the method of claim 11 obvious, as discussed above, wherein the extracted raw material is subjected to further processing (Kotiranta, Figure 1, Page 4, lines 22-23, “The thus obtained calcium depleted iron containing material 13 is then fed to a pyrometallurgical treatment stage…”). Regarding claim 21, Kotiranta renders the method of claim 11 obvious, as discussed above, wherein the alkaline earth is calcium (Kotiranta, Page 3, lines 12-27, calcium rich iron containing material). Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Kotiranta (WO 2017/162901 A1), as applied to claim 11 above, and further evidenced by Tissue (Basics of Analytical Chemistry and Chemical Equilibria – A Quantitative Approach (2nd Edition), 2023). Regarding claim 12, Kotiranta renders the method of claim 11 obvious, as discussed above, wherein the precipitant is carbon dioxide (Kotiranta, Page 6, line 36 – Page 7, line 1), and wherein the weak acid is a weaker acid than carbonic acid (Kotiranta, Page 5, line 13, ammonium chloride; Tissue, Page 202, Table 5.6 shows that the pKa of the ammonium ion is 9.246, which is greater than the pKa of carbonic acid, which the instant Specification states to be 6.36 in Paragraph [0027]). Claims 16-19 are rejected under 35 U.S.C. 103 as being unpatentable over Kotiranta (WO 2017/162901 A1), as applied to claim 11 above, and further in view of ‘367 (U.S. 2015/0125367) Regarding claim 16, Kotiranta renders the method of claim 11 obvious, as discussed above, but does not teach that the extracted raw material is separated from the alkaline earth precipitate and from the regenerated weak organic acid lixiviant following contacting with the precipitant. However, ‘367 teaches an analogous method for recovering calcium from a material using a weak organic acid lixiviant (‘367, [0055], amino acids) followed by precipitation of calcium with carbon dioxide (‘367, [0018]), wherein the extracted raw material is separated from the alkaline earth precipitate and from the regenerated weak organic acid lixiviant (‘367, [0042], “The inventors have determined that such amine-based lixiviants can be regenerated using carbon dioxide.”) following contacting with the precipitant (‘367, [0018], “The alkaline earth precipitate and the extracted raw material are separated, and some or all of the regenerated lixiviant is returned to the reactor.”). A reference is analogous art to the claimed invention if: (1) the reference is from the same field of endeavor as the claimed invention (even if it addresses a different problem); or (2) the reference is reasonably pertinent to the problem faced by the inventor (even if it is not in the same field of endeavor as the claimed invention). See MPEP 2141.01(a).I. In the instant case, ‘367 is reasonably pertinent to the problem of continuous operation of calcium leaching from a material using a weak acid and precipitation with carbon dioxide (Instant Specification, [0019] and [0034]; ‘367, [0017]-[0018]) and is in the same field of endeavor of hydrometallurgical recovery of alkaline earth metals from solid waste. It would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to have modified Kotiranta such that the extracted raw material is separated from the alkaline earth precipitate and from the regenerated weak organic acid lixiviant following contacting with the precipitant, as ‘367 teaches that this single separation step results in efficient recovery or segregation of the desired alkaline earth carbonate from the raw material (‘367, [0100]). A person having ordinary skill in the art would have been motivated to incorporate the continuous processing of ‘367 into Kotiranta’s method, which would include this solid-solid separation step, as ‘367 teaches that this uses a smaller amount of lixiviant than non-continuous processes (‘367, [0099]). The fact that the lixiviant in ‘367 uses an amine-containing lixiviant species rather than acetic acid, for example, is immaterial to this obviousness, as Kotiranta already teaches that the lixiviant is regenerated and reused in the same way by passing CO2 gas into the leached calcium-containing solution (Kotiranta, Page 6, line 35 – Page 7, line 4). In addition to the explicit motivation provided by ‘367, it has been generally held that making a batch process continuous does not in itself constitute a patentable distinction. See In re Dilnot, 319 F.2d 188, 138 USPQ 248 (CCPA 1963) (Claim directed to a method of producing a cementitious structure wherein a stable air foam is introduced into a slurry of cementitious material differed from the prior art only in requiring the addition of the foam to be continuous. The court held the claimed continuous operation would have been obvious in light of the batch process of the prior art.). See also MPEP 2144.04.V.E. Regarding claim 17, modified Kotiranta renders the method of claim 16 obvious, as discussed above, wherein separation is performed on the basis of density or particle size (‘367, [0019]). For reasons discussed above with respect to claim 16, it would have been obvious to incorporate the separation steps of ‘367 into Kotiranta’s method, which would include separation on the basis of density or particle size. Regarding claims 18-19, modified Kotiranta renders the method of claim 16 obvious, as discussed above, wherein the precipitant is introduced into the reactor in an essentially continuous manner (‘367, [0104]), and wherein separating is performed in an essentially continuous manner (‘367, [0104]). These components of ‘367 would be obvious to incorporate to affect the continuous processing rendered obvious as discussed above for claim 16, as a continuous process would predictably entail its component sub-processes to be enacted continuously. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to ZACHARY J. BAUM whose telephone number is (571)270-0895. The examiner can normally be reached Monday-Friday 8:30-5:00. 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, Anthony Zimmer can be reached at 571-270-3590. 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. /ZACHARY JOHN BAUM/Examiner, Art Unit 1736 /ANTHONY J ZIMMER/Supervisory Patent Examiner, Art Unit 1736
Read full office action

Prosecution Timeline

Mar 08, 2023
Application Filed
Aug 28, 2025
Non-Final Rejection — §103, §112
Mar 30, 2026
Response after Non-Final Action

Precedent Cases

Applications granted by this same examiner with similar technology

Patent 12595183
METHOD FOR PRODUCTION OF SHEET PHASE PSEUDO-BOEHMITE USING COUETTE-TAYLOR VORTEX REACTION
2y 5m to grant Granted Apr 07, 2026
Patent 12595185
PROCESS FOR RECOVERING MATERIALS FROM BAUXITE RESIDUE, MICROWAVE REACTOR FOR HEATING MINING PRODUCTS AND METHOD FOR HEATING A MINING PRODUCT
2y 5m to grant Granted Apr 07, 2026
Patent 12592383
Method of Manufacturing Cathode Active Material for Lithium Secondary Battery
2y 5m to grant Granted Mar 31, 2026
Patent 12590353
PROCESS FOR THE RECOVERY OF HIGH PURITY Metallic SODIUM AND THE SAFE TREATMENT OF HIGH CALCIUM CONTENT SODIUM SLAG
2y 5m to grant Granted Mar 31, 2026
Patent 12584190
Methods for Selective Recovery of Rare Earth Elements and Metals from Coal Ash by Ionic Liquids
2y 5m to grant Granted Mar 24, 2026
Study what changed to get past this examiner. Based on 5 most recent grants.

AI Strategy Recommendation

Get an AI-powered prosecution strategy using examiner precedents, rejection analysis, and claim mapping.
Powered by AI — typically takes 5-10 seconds

Prosecution Projections

1-2
Expected OA Rounds
79%
Grant Probability
93%
With Interview (+14.0%)
2y 11m
Median Time to Grant
Low
PTA Risk
Based on 109 resolved cases by this examiner. Grant probability derived from career allow rate.

Sign in for Full Analysis

Enter your email to receive a magic link. No password needed.

Free tier: 3 strategy analyses per month