DETAILED ACTION
Claims 1, 3-9, 14-15, and 17-24 are pending, and claims 1, 3-4, and 7 are currently under review.
Claims 2, 10-13, 16, and 25-27 are cancelled.
Claims 5-6, 8-9, 14-15, and 17-24 are withdrawn.
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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 12/05/2025 has been entered.
Response to Amendment
The amendment filed 12/05/2025 has been entered. Claims 1, 3-9, 14-15, and 17-24 remain(s) pending in the application.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim(s) 1, 3, and 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Villarreal-Trevino (US 6,027,545) in view of Shao et al. (CN112899427, machine translation referred to herein), Motamedhashemi (US 2016/0083811), and Metius et al. (US 2013/0312571).
Regarding claim 1, Villarreal-Trevino discloses a method for producing directly reduced iron with a hydrogen-rich gas stream [abstract, col.4 ln.1-8]. Said method of Villarreal-Trevino includes the steps of:
providing a reduction reactor (10) (ie. shaft furnace) for reducing iron oxide to metallic iron with said hydrogen-rich gas stream
providing a spent top gas stream (22) to a water washer and cooler (24) to remove dust (ie. particulates) [col.5 ln.48 to col.6 ln.6, fig.1]. The examiner notes that the water washing disclosed by Villarreal-Trevino naturally meets the common definition of gas scrubbing; and the cooling to cause condensation taught by Villarreal-Trevino would be understood by one of ordinary skill to naturally be removing steam (ie. water vapor) to at least some extent.
said aforementioned gas stream is subsequently processed and separated to create a hydrogen-rich stream and a hydrogen-lean stream, wherein one of ordinary skill would recognize that the hydrogen-rich stream having more than 99% hydrogen would naturally have a reduced amount of non-hydrogen compounds relative to the initially scrubbed top gas stream [col.6 ln.21-40]. Villarreal-Trevino further teaches that the lean gas stream includes residual H2, CO, CO2, CH4, and N2, with H2 included in a low amount of 10 to 25 percent [col.10 ln.55-65].
said hydrogen-rich gas is then recycled, mixed with another reducing gas stream (42) to create a combined reducing gas (48), and heated to 750 to 1050 degrees C prior to introduction into the furnace for further reduction [col.6 ln.12-61, fig.1]. The examiner notes that the overlap between the heating temperature of Villarreal-Trevino et al. and that as claimed is prima facie obvious. See MPEP 2144.05(I).
Accordingly, the disclosure of Villarreal-Trevino meets all of the claimed features except: 1) an electric reducing gas heater as claimed, and 2) injection of the inert stream into a transition zone for carburization as claimed.
Regarding 1), Villarreal-Trevino does not expressly teach that the reducing gas heater is non-fired as claimed. Shao et al. discloses that it is known to utilize electric heaters for heating reducing gas in iron reduction processes such that heating can be provide with clean electric energy [0001, 0007]. Therefore, it would have been obvious to one of ordinary skill to modify the method of Villarreal-Trevino by utilizing electric heaters for heating reducing gas with clean electric energy as taught by Shao et al.
Regarding 2), Villarreal-Trevino does not expressly teach using the lean gas for injection into a transition zone for carburization as claimed. Motamedhashemi discloses that it is known to utilize COG gas for producing iron (ie. recycling off gas) [abstract]; wherein hydrocarbon rich tail gas can be injected into a transition zone of the reduction furnace in order to control carbon content of the direct reduced iron (ie. control carburization). Although Motamedhashemi is directed to COG gas in general rather than specifically a lean/inert stream, one of ordinary skill would have recognized that the lean gas of Villarreal-Trevino is also rich in hydrocarbons and would therefore be similarly useful for controlling carburization, which is the express purpose disclosed by Motamedhashemi as stated above. Therefore, it would have been obvious to one of ordinary skill to modify the method of Villarreal-Trevino by utilizing the lean gas (which is rich in hydrocarbons) of Villarreal-Trevino for injection into a transition zone of the furnace to control carburization as taught by Motamedhashemi. The examiner notes that a portion of the lean gas of Villarreal-Trevino (which contains CH4) can be considered as a hydrocarbon bearing gas, and said lean gas would naturally be mixed/blended during processing based on gas flow mechanics, which meets the limitation of “blending with a hydrocarbon bearing gas” as claimed. Metius et al. further teaches that it is known to utilize recycled off gas (ie. inert stream) for a variety of different uses such as heater fuel (as expressly taught by Villarreal-Trevino) or as transition zone injection gas to control carbon content in the iron (ie. carburization) [0004-0005, 0052, 0048, 0055]. In other words, Metius et al. discloses that recycled off gases (ie. inert stream) can be equivalently utilized for heater fuel (as taught by Villarreal-Trevino) or for transition zone injection gas for carburization as claimed, which further supports the above position of obviousness of using the lean gas of Villarreal-Trevino for a transition zone gas as taught by Motamedhashemi. See MPEP 2144.06.
Alternatively, Villarreal-Trevino does not expressly teach a scrubber as claimed. Motamedhashemi and Metius et al. both further disclose that it is known to utilize a scrubber to clean the spent top gas to be recycled [0011 & 0030, respectively]. Therefore, it would have been obvious to one of ordinary skill to modify the method of Villarreal-Trevino by including a scrubber to clean the recycled gas as taught by Motamedhashemi or Metius et al. The examiner notes that cleaning as taught by Motamedhashemi or Metius et al. would naturally pertain to removal of undesired components such as steam and particulates
Regarding claim 3, the aforementioned prior art discloses the method of claim 1 (see previous). Metius et al. further teaches that it is well-known to those of ordinary skill in the art to remove CO2 from the aforementioned off gases (ie. inert stream) prior to mixing with hydrogen bearing gas [0004]. The examiner notes that removal of CO2 would naturally require an apparatus for removing CO2 (ie. CO2 stripper) as claimed and would naturally result in an inert stream with CO2 removed (ie. lean CO2 gas) added to a transition zone of the furnace for carburization as suggested by the prior art combination and explained above.
Regarding claim 7, the aforementioned prior art discloses the method of claim 1 (see previous). Metius et al. further teaches that CO2 removal (ie. CO2 stripper) can be pressure swing adsorption unit [0052].
Claim(s) 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over Villarreal-Trevino (US 6,027,545) and others as applied to claim 1 above, and further in view of Doshi (US 4,645,516).
Regarding claim 4, the aforementioned prior art discloses the method of claim 1 (see previous). The aforementioned prior art does not expressly teach separation of the hydrogen-rich stream and hydrogen-lean stream through membrane gas separation as claimed. Doshi discloses that membrane systems are commercially feasible means for separating gas mixtures [col.1 ln.11-20]. Therefore, it would have been obvious to one of ordinary skill to modify the method of the aforementioned prior art by utilizing a membrane for gas separation as a commercially feasible gas separation means as taught by Doshi.
Response to Arguments
Applicant's arguments filed 12/05/2025 have been fully considered but they are not persuasive.
Applicant argues that Villarreal-Trevino requires using the lean gas stream for fuel because this concept is depicted in every embodiment. The examiner cannot concur. As stated previously, specific embodiments do not constitute a teaching away from the broader disclosure of the prior art. See MPEP 2123. Again, Villarreal-Trevino expressly and broadly teaches that the lean gas stream “may be used as fuel…” (emphasis added) [col.6 ln.61-65]. One of ordinary skill would understand that the term “may” indicates the possible/potential use of the lean gas stream as fuel rather than a strict requirement. Villarreal-Trevino further does not expressly teach away from using the leas gas stream for other purposes. Therefore, the examiner cannot concur with applicant’s unreasonably narrow interpretation of the disclosure of Villarreal-Trevino.
Applicant argues that Shao et al. is directed to a heat exchanger for removing water. The examiner cannot concur. Shao et al. expressly and broadly teaches utilizing electrical energy heating for ironmaking systems, and is not solely directed to only simple heat exchangers [abstract, 0006-00010]. One of ordinary skill would understand that “heating for ironmaking systems” as taught by Shao et al. reasonably pertains to a reducing gas heater.
The examiner notes that amending the claims to distinguish over the prior art (ie. Specifying inert/oxidant stream components, specifying inert/oxidant stream components after stripping, processing parameters, etc.) would appear to overcome the previous rejections.
Applicant’s arguments, filed 12/05/2025 with respect to the rejection(s) over Metius et al. have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of both Motamedhashemi and Metius et al. together as seen above.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to NICHOLAS A WANG whose telephone number is (408)918-7576. The examiner can normally be reached usually M-Th: 7-5.
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/NICHOLAS A WANG/Primary Examiner, Art Unit 1734