Prosecution Insights
Last updated: April 19, 2026
Application No. 18/044,677

SYSTEM AND METHOD FOR PRODUCING SULFUR DIOXIDE AND ASSOCIATED SULFURIC ACID PLANT

Non-Final OA §102
Filed
Mar 09, 2023
Examiner
YOUNG, NATASHA E
Art Unit
1774
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Chemetics Inc.
OA Round
1 (Non-Final)
83%
Grant Probability
Favorable
1-2
OA Rounds
2y 8m
To Grant
92%
With Interview

Examiner Intelligence

Grants 83% — above average
83%
Career Allow Rate
887 granted / 1070 resolved
+17.9% vs TC avg
Moderate +9% lift
Without
With
+9.2%
Interview Lift
resolved cases with interview
Typical timeline
2y 8m
Avg Prosecution
24 currently pending
Career history
1094
Total Applications
across all art units

Statute-Specific Performance

§101
1.5%
-38.5% vs TC avg
§103
42.9%
+2.9% vs TC avg
§102
20.0%
-20.0% vs TC avg
§112
21.0%
-19.0% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1070 resolved cases

Office Action

§102
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 . Election/Restrictions Applicant’s election without traverse of Group I (claims 1-8) in the reply filed on December 3, 2025 is acknowledged. Claim Rejections - 35 USC § 102 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 the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claim(s) 1 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Dijkstra (CA 3021202 A1). Regarding claim 1, Dijkstra discloses a system for the production of sulfur dioxide gas comprising: a submerged combustion reactor for the combustion of molten sulfur to sulfur dioxide comprising an inlet for a supply of molten sulfur, an inlet for a supply of oxygen at > 90% purity by volume, an inlet for condenser sulfur, and an outlet, since Dijkstra discloses using a submerged combustion system where the oxygen is sparged into molten sulfur, the majority of the sulphur contained in the process gas is condensed in the sulphur condenser and returned to the combustion system (see page 6, lines 1-8 and figures 2-3); a vapour phase combustion chamber (secondary combustion chamber) for the combustion of sulfur vapour to sulfur dioxide comprising an inlet connected to the outlet of the submerged combustion reactor, an inlet for a supply of oxygen at > 90% purity by volume, and an outlet, since Dijkstra discloses that in the secondary combustion chamber/system the process gas is mixed with additional oxygen and recycled process gas from the absorber tower to convert any remaining sulphur to SO2, and that the O2:SO2 ratio of the process gas (see figures 2-3 and page 6, line 1-32); and an apparatus (superheater) for cooling a gas and for condensing sulfur vapor into liquid sulfur comprising an inlet connected to the outlet of the vapour phase combustion chamber, an outlet for liquid sulfur connected to the condensed sulfur inlet of the submerged combustion reactor, and an outlet for a gas mixture comprising sulfur dioxide and residual sulfur vapour (see figures 2-3 and page 6, line 1-32), since Dijkstra discloses that the process gas is cooled in a superheater (see page 6, lines 10-14) and since the use of the apparatus isn't limiting or the material the apparatus acts upon isn't limiting. Allowable Subject Matter Claims 2-3 are allowed. The closest prior art references are Dijkstra (CA 3021202 A1) and Schendel (US 5,204,082). Regarding claim 2-3, Dijkstra fails to disclose or suggest a system wherein the apparatus for cooling a gas and for condensing sulfur vapour into liquid sulfur comprises: a heat exchanger for cooling a gas comprising the inlet connected to the outlet of the vapour phase combustion chamber, and an outlet; and a sulfur condenser for condensing sulfur vapour into liquid sulfur comprising an inlet connected to the outlet of the heat exchanger, the outlet for liquid sulfur connected to the condensed sulfur inlet of the submerged combustion reactor, and the outlet for a gas mixture comprising sulfur dioxide and residual sulfur vapour; and wherein the sulfur condenser is sized to condense less than 10 times the mass of molten sulfur supplied to the submerged combustion reactor. The following is a statement of reasons for the indication of allowable subject matter: Claims 4-8 are allowed. Regarding claim 4, Dijkstra discloses a sulfur dioxide production system of claim 1 (see figures 2-3 and page 6, line 1-32). Dijkstra fails to disclose or suggest a sulfuric acid plant comprising: a secondary combustion chamber for the combustion of residual sulfur vapour to sulfur dioxide comprising an inlet connected to the outlet of the sulfur condenser for the gas mixture, an inlet for an oxygen containing gas, and an outlet for process gas consisting essentially of sulfur dioxide and oxygen; a contact apparatus for converting sulfur dioxide to sulfur trioxide comprising an inlet connected to the process gas outlet of the secondary combustion chamber and an outlet for sulfur trioxide; and an absorption system for converting sulfur trioxide to sulfuric acid comprising an inlet connected to the sulfur trioxide outlet of the contact apparatus, and an outlet for sulfuric acid. Claims 5-8 depend on claim 4. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to NATASHA E YOUNG whose telephone number is (571)270-3163. The examiner can normally be reached M-F 7:00 am - 6:00 pm. 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, Wang Claire can be reached at 571-270-1051. 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. NATASHA E. YOUNG Examiner Art Unit 1774 /NATASHA E YOUNG/Primary Examiner, Art Unit 1774
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Prosecution Timeline

Mar 09, 2023
Application Filed
Feb 05, 2026
Non-Final Rejection — §102 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
83%
Grant Probability
92%
With Interview (+9.2%)
2y 8m
Median Time to Grant
Low
PTA Risk
Based on 1070 resolved cases by this examiner. Grant probability derived from career allow rate.

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