Prosecution Insights
Last updated: April 19, 2026
Application No. 18/026,061

Device to inject a reducing gas into a shaft furnace

Final Rejection §103
Filed
Mar 13, 2023
Examiner
ABOAGYE, MICHAEL
Art Unit
1733
Tech Center
1700 — Chemical & Materials Engineering
Assignee
ArcelorMittal
OA Round
2 (Final)
75%
Grant Probability
Favorable
3-4
OA Rounds
3y 0m
To Grant
99%
With Interview

Examiner Intelligence

Grants 75% — above average
75%
Career Allow Rate
795 granted / 1054 resolved
+10.4% vs TC avg
Strong +38% interview lift
Without
With
+38.3%
Interview Lift
resolved cases with interview
Typical timeline
3y 0m
Avg Prosecution
34 currently pending
Career history
1088
Total Applications
across all art units

Statute-Specific Performance

§101
0.4%
-39.6% vs TC avg
§103
45.4%
+5.4% vs TC avg
§102
21.6%
-18.4% vs TC avg
§112
26.6%
-13.4% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1054 resolved cases

Office Action

§103
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 . Status of Claims Claim 13 has been amended, claims 19 and 21 have been canceled, and therefore claims 13-18, 20 and 22 -4 are currently under consideration in the application. Drawings The drawings are objected to under 37 CFR 1.83(a). The drawings must show every feature of the invention specified in the claims. Therefore, the triangular shape front face of the external casing recited in the amended claim 22 must be shown or the feature(s) canceled from the claim(s). No new matter should be entered. Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance. Claim Objections In claim 13, line 8, it is suggested to replace “the front face including an upper and a lower part,” with -- the front face including an upper part and a lower part, --Appropriate correction is required. 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. Claims 13-18, 20 and 22-24 are rejected under 35 U.S.C. 103 as being unpatentable over Slagley (US Patent No. 4,572,487) in view of Stoecker (US Patent No. 1,994,115) and Miller (US Patent No.1,298,761). Regarding claims 13, 15, 23 and 24, Slagley teaches a device (i.e., tuyere (12), see abstract, column 1, lines 5-20, column 3, lines 44-56 and figures 1&2) configured to inject a hot gas into a shaft furnace (see column 3, lines 44-45), the device comprising: an external casing (i.e., main tubular tuyere portion (15), see figure 2 and column 3, lines 58-68) having a rear (i.e., upstream end (16) see figure 2 and column 3, lines 58-68) and a front face (i.e. downstream nose portion (17) , see figure 2 and column 3, lines 58-68), the front face being provided with an outlet for gas injection into the shaft furnace (see in figure 2, the nose portion (17) defines an opening for gas discharge into the furnace reaction space); and an internal casing (i.e., the replaceable liner (20) comprising a metallic liner (22) and a refractory layer (23), see figures 2 and 4 and column 3, lines 58-68) located inside the external casing (15) and made of a steel (i.e., the liner (22) is made of stainless steel, see column 5, lines 27-29) able to resist to a temperature up to 1200°C (see column 4, lines 18-32 and column 5, lines 18-30). Furthermore, it is noted that though the tuyere assembly of Slagley is used for performing injection of hot gas or hot air blast into the blast furnace and not necessarily for performing reducing gas injection as stated in the preamble of the claim, however, it is capable of injection a reducing gas in that (1) a reducing gas is in the same state of matter as hot gas and (2) it includes substantially all and/or the same structure features as claimed. In addition, the reducing as recited in the instant claim only constitutes an intended use of the claim injection device. In addition, with reference to MPEP 2114.II., the Court held that "[A]pparatus claims cover what a device is, not what a device does, and that A claim containing a "recitation with respect to the manner in which a claimed apparatus is intended to be employed does not differentiate the claimed apparatus from a prior art apparatus" if the prior art apparatus teaches all the structural limitations of the claim. Slagley fails to teach an injection device in which the front face of the external casing is composed of an upper part and of a lower part, the lower part being recessed from the upper part and the gas injection outlet being provided in the lower part of the front face or the lower part being inwardly chamfered from the upper part and the gas injection outlet being provided in the lower part of the front face. Stoecker teaches an injection device in the form of a tuyere configured for gas injection into a shaft furnace (see Stoecker, figures 1 and 3 and the entire disclosure); wherein the tuyere includes an external casing having a front face composed of an upper part (i.e. wedge like insertion 2, see Stoecker , figures 1 and 3 and page 1, column 2, lines 5-20) and of a lower part (i.e., lower inner nozzle plate 3, see Stoecker , figures 1 and 3 and page 1, column 2, lines 5-20) the lower part being recessed from the upper part and the gas injection outlet being provided in the lower part of the front face (see figure 3 shows as such) or the lower part being inwardly chamfered (see in figure 3, the lower part or plate 3 is chamfered) from the upper part; and with and the gas injection outlet being provided in the lower part of the front face. It would have been obvious to one of ordinary skill in the art at the time the invention was made to modify the injection device or tuyere of Slagley to include lower part being recessed from the upper part and lower part being inwardly chamfered from the upper part as taught by Stoecker to provide the benefit of preventing material from obstructing the tuyere gas injection outlet (see Stoecker, entire disclosure). Slagley in view of Stoecker fails to teach a stone box on the upper part of the front face. Miller teaches a device (i.e., supplementary tuyere 150, see figures 1 &3, page 2, lines 86-104 and page 3, lines 1-14) for injecting at least a hot gas into a shaft furnace, the device having a nozzle portion (34, see figures 1 and 3) defining an upper part and a lower part (see figures 1 and 3), and a fire brick mass (38, see figure 3) provide at said upper part to reinforce and strengthen said upper part to increase the service life of the front face or hot face of the nozzle portion (34, see page 3, lines 1-14). It would have been obvious to one of ordinary skill in the art at the time the invention was made to modify the injection device or tuyere of Slagley in Stoecker, to provide a fire brick mass at said upper part of the front face or hot face of the nozzle portion as exemplified by Miller so as to provide the advantage and/or benefit of reinforcing and/or strengthening said upper part to increase the service life of the front face or hot face of the nozzle portion. Regarding claim 14, Slagley in view of Stoecker and Miller teaches an injection device in which the refractory layer (23, see Slagley, figures 2 and 4) is located between the external casing (15) and the internal casing (steel liner 22 of the inner casing, see Slagley, column 3, lines 62-68). Regarding claim 16, Slagley in view of Stoecker and Miller teaches an injection device or tuyere (12, see Slagley, figure 2) which comprises at least an inner casing (22) that is uncooled or in other words has no attached cooling jacket provided (see Slagley, column 5, lines 14-17); and therefore; Slagley figure 2 substantially reads on the claim. Regarding claim 17, Slagley in view of Stoecker and Miller teaches an injection device in which the shaft furnace is a blast furnace (see Slagley, abstract and column 3, lines 44-45). Regarding claim 18, Slagley in view of Stoecker and Miller teaches an injection device that is fastened or bolted to the shaft furnace or blast furnace wall (10, see Slagley, figure 1 and column 4, lines 55 -68). Regarding claim 20, Slagley in view of Stoecker and Miller teaches a tuyere (12) defining an internal casing (22&23, see Slagley, figures 1 and 2, shows) that is inclined slightly with respect to the horizontal axis at a none zero angle to blast furnace wall, the claimed angle of inclination α between 0 and 30° is met. Regarding claim 22, Slagley in view of Stoecker and Miller teaches an injection device in which the front face of the external casing (i.e., main tubular tuyere portion (15), see Slagley, figure 2 and column 3, lines 58-68) that appears to be circular in shape, but fails to teach said front face being triangular in shape as claimed. However, with reference to MPEP 2144.04. IV.B which pertains to the obviousness of changes in shape, similar to the instantly-claimed shape of the front face of the external casing and that taught by Slagley, the court held that the configuration of the claimed disposable plastic nursing container “was a matter of choice which a person of ordinary skill in the art would have found obvious absent persuasive evidence that the particular configuration of the claimed container was significant.” In this instant case the circular shape front face of the external casing of Slagley equally performs hot gas injection into the blast furnace reaction space effective to yield the expected result in the iron ore smelting process. Furthermore, none of the figures in the drawing show said claimed triangular shape front face of the external casing to allow one of ordinary skill in the art to understand and/or appreciate the structure being claimed for a prior art to be applied to. Response to Arguments Applicant’s arguments, filed 12/15/2025, with respect to the rejection(s) of claim 13-19, 20 and 22-24 under 103 have been fully considered and are persuasive. However, upon further consideration, and the amendment to the independent claim 13, a new ground(s) of rejection is made by Slagley in view of Stoecker and Miller, where Miller is a new reference introduced into the instant office action dues to said amendment. Applicant’s principal argument is that Slagley and Stoecker, either considered individually or as combined do not render obvious an injection device that includes a stone box on the upper part of the front face” as recited in amended claim 13. In response, the Examiner recognizes that Slagley in view of Stoecker does not particularly teach a stone box provided on the upper part of the front face as in the amended claim 13, however Miller teaches a known a device for injecting at least a hot gas into a shaft furnace that includes a nozzle portion defining an upper part and a lower part and a fire brick mass provide at said upper part for the purpose of reinforce and strengthen said upper part to increase the service life of the front face or hot face of the nozzle portion. Therefore, Miller remedies the deficiencies of Slagley in view of Stoecker, and/or Slagley in view of Stoecker and Miller reads on claim 13 as amended. Conclusion The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Gammon et al. (US 4,371,151) is also cited in PTO-892. 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. Any inquiry concerning this communication or earlier communications from the examiner should be directed to MICHAEL ABOAGYE whose telephone number is (571)272-8165. The examiner can normally be reached 8:30AM-5:00PM. 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 Hendricks can be reached at 571-272-1401. 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. /M.A/ Examiner, Art Unit 1733 /JESSEE R ROE/ Primary Examiner, Art Unit 1759
Read full office action

Prosecution Timeline

Mar 13, 2023
Application Filed
Sep 12, 2025
Non-Final Rejection — §103
Dec 15, 2025
Response Filed
Feb 05, 2026
Final Rejection — §103 (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

3-4
Expected OA Rounds
75%
Grant Probability
99%
With Interview (+38.3%)
3y 0m
Median Time to Grant
Moderate
PTA Risk
Based on 1054 resolved cases by this examiner. Grant probability derived from career allow rate.

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