Prosecution Insights
Last updated: April 19, 2026
Application No. 17/792,576

CALCINATION APPARATUS AND PROCESS USING HYDROGEN

Non-Final OA §102§103§112
Filed
Jul 13, 2022
Examiner
FIORITO, JAMES A
Art Unit
1731
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Rio Tinto Alcan International Limited
OA Round
1 (Non-Final)
71%
Grant Probability
Favorable
1-2
OA Rounds
2y 11m
To Grant
99%
With Interview

Examiner Intelligence

Grants 71% — above average
71%
Career Allow Rate
502 granted / 711 resolved
+5.6% vs TC avg
Strong +29% interview lift
Without
With
+29.0%
Interview Lift
resolved cases with interview
Typical timeline
2y 11m
Avg Prosecution
36 currently pending
Career history
747
Total Applications
across all art units

Statute-Specific Performance

§101
0.1%
-39.9% vs TC avg
§103
45.9%
+5.9% vs TC avg
§102
24.8%
-15.2% vs TC avg
§112
27.2%
-12.8% vs TC avg
Black line = Tech Center average estimate • Based on career data from 711 resolved cases

Office Action

§102 §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 . Election/Restrictions Applicant's election with traverse of claim 1-6, 8, 10, 12-16, 19-20, and 22 in the reply filed on 12/11/2025 is acknowledged. The traversal is on the ground(s) that the prior art of Misura US 5141734 does not teach special technical feature of claim 1. This is not found persuasive because the special technical feature of claim 1 is found obvious according to the prior art rejections below. The requirement is still deemed proper and is therefore made FINAL. 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 2, 10, 13, 16 and 22 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. In claims 2 and 13, the phrase “transferring at least some of the steam produced in and discharged from the process to the process”, the scope of this phrase is indefinite because it calls for both the discharging of steam and the transferring of the steam to the same process, which is unclear how steam can be both discharged and transferred to the process. For the purpose of examination, the Office will interpret this feature to mean that at least a portion of the steam produced is recycled back to the calcination process. In claims 10, 16 and 22, the phrase “the oxygen is supplied as oxygen or oxygen-enriched air and not air and not oxygen-enriched air” is indefinite because unclear whether oxygen is required or prohibited by the claim. Claim Rejections - 35 USC § 102 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) 19, and 22 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Mills WO 2008/052249. Regarding claim 19, Mills teaches a process of calcining aluminum hydroxide (Abstract) by directly calcining at least a portion of the aluminum hydroxide with steam (Abstract). Mills also teaches that the process may include another calcination stage, wherein aluminum hydroxide is further calcined with direct or indirect combustion of the fuel gases (Claim 10). The process of Mills is performed in a plant (Figures 1 and 2) that would inherently require startup, and Mills teaches that the aluminum hydroxide is preheated by the combustion products (Page 12, l. 25 – Page 13, l. 10), preheating would inherently end when a steady state temperature condition was reached. Regarding claim 22, the combustion of the fuel would inherently require oxygen. 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. Claim(s) 1-6, 8, 10, 12-16, and 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Mills WO 2008/052249 in view of Bligh AU 2005237179. Regarding claim 1, 12, 14-15, and 20, Mills teaches a process of calcining aluminum hydroxide (Abstract) by directly calcining at least a portion of the aluminum hydroxide with steam (Abstract). Mills also teaches that the process may include another calcination stage, wherein aluminum hydroxide is further calcined with direct or indirect combustion of the fuel gases (Claim 10). As a matter of claim interpretation claim 1 includes the possibility of calcining the aluminum hydroxide by combusting hydrogen both directly and indirectly. Directly meaning that hydrogen is combusted in the same vessel where the aluminum hydroxide is being calcined and indirectly meaning that hydrogen is combusted in a separate vessel and the heat produced therein is transferred to the aluminum hydroxide calcination vessel. Mills teaches that a fuel may be combusted to calcine aluminum hydroxide to alumina both directly and indirectly (Claim 10). Mills is silent with respect the names of the fuels that may be combusted. Bligh teaches a process that for calcining aluminum hydroxide to form alumina to liberate the water in the crystallize hydroxide (Abstract, Page 7, l. 25-30). Bligh teaches that the combustion heat fuel may include a burning process of hydrogen (Page 2, l. 26). The burning of hydrogen inherently requires a mixture of oxygen and hydrogen, which produces water. The steam generated in the reaction chamber would be considered transport gas because it would transport the gases from the reaction chamber. At the time of invention, it would have been obvious to the person having ordinary skill in the art to perform the process of Mills while using the burning of hydrogen as the fuel source in view of Bligh. The suggest or motivation for doing so would have been to provide a suitable fuel in Mills that was required but not disclosed. The person having ordinary skill in the art would have understood that the use of hydrogen as fuel was a heat source that would have provided predictable results in view of Bligh (Bligh, Page 2, l. 26). Regarding claim 2 and 13, Mills teaches that the steam produced in the process may be recycled (Page 13, l. 10). Regarding claim 3, Mills teaches that the temperature is at least 250 degrees C, which is above the 100 deg C condensation temperature of water (Page 6, l. 6). Regarding claim 4, Mills does not expressly state that the pressure is at atmospheric pressure. Bligh teaches that the calcination may occur at ambient pressure in order to produce a condensed water that is may be used for consumption (Page 2-3). At the time of invention, it would have been obvious to the person having ordinary skill in the art to perform the process of Mills including calcining at ambient temperature in view of Bligh. The suggestion or motivation for doing so would have been to provide a condensable water supply that could be used for consumption (Bligh Pages 2-3). Regarding claim 5, the steam generated in the reaction chamber would be considered transport gas because it would transport the gases from the reaction chamber. Regarding claim 6, the steam generated in the reaction chamber is a heat transfer medium because it transfers heat to the aluminum hydroxide to drive the calcination. Regarding claim 8, Mills and Bligh do not expressly state that the flue gas from the reaction chamber is 95% by volume steam. However, since the reaction in the reaction chamber is the combustion of hydrogen, which produces steam as a product. It would be obvious to the person having ordinary skill in the art to completely combust the hydrogen before it leaves the reaction chamber, which would result if a flue gas having a steam content of greater than 95%. Regarding claim 10 and 16, hydrogen is combusted by a reaction with oxygen. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to JAMES A FIORITO whose telephone number is (571)272-9921. The examiner can normally be reached Monday-Friday 9AM-5PM. 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, Amber Orlando can be reached at (571) 270-3149. 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. /JAMES A FIORITO/Primary Examiner, Art Unit 1731
Read full office action

Prosecution Timeline

Jul 13, 2022
Application Filed
Jan 15, 2026
Non-Final Rejection — §102, §103, §112 (current)

Precedent Cases

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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
71%
Grant Probability
99%
With Interview (+29.0%)
2y 11m
Median Time to Grant
Low
PTA Risk
Based on 711 resolved cases by this examiner. Grant probability derived from career allow rate.

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