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 .
Priority
Receipt is acknowledged of a certified copy of JP 2021-098118 field June 11, 2021 as required by 37 CFR 1.55. Receipt is also acknowledged of WO 2022/259805, the WIPO publication of PCT/JP2022/020007 filed May 12, 2022.
Claim Status
This Office Action is in response to Applicant’s Claim Amendments and Remarks filed August 3, 2026.
Claims Filing Date
August 3, 2026
Amended
1, 22
Cancelled
4-6, 9-19
Pending
1-3, 7, 8, 20-22
Withdrawn Claim Objection
The following objection is withdrawn due to claim amendment:
Claim 1 line 3 “CaO-and-Al2O3-and MgO-containing slag” having inconsistent dashes, -, and spaces, .
Withdrawn Claim Rejections - 35 USC § 112
The following 112(a) rejections are withdrawn due to claim amendment:
Claim 1 lines 22-28 “the denitrification treatment reduces the nitrogen concentration in the molten steel to a predetermined value and the molten steel temperature after the denitrification treatment is set relative to a reference molten steel temperature that would be required to reduce the nitrogen concentration in the molten steel to the predetermined value with the denitrification treatment when there is no MgO in the slag, such that the molten steel temperature after the denitrification treatment corresponds to 5°C or more than the reference molten steel temperature for each 1.0 mass % of MgO in the slag”.
The applicant persuasively argues this concept is re-written in part as an equation (para. spanning pp. 4-5).
Claim 1 line 23 “predetermined value”.
The applicant persuasively argues support in [0026], [0028], [0030], and [0033] (p. 5 para. 2).
[0030] recites a Fifth Embodiment “the nitrogen concentration [N] in the molten steel is 35 mass ppm or lower and thus a low nitrogen concentration range is reached.” [0033], Examples, recites “good results with the N concentration [N]f after the treatment being 35 mass ppm or lower”.
Claim 1 lines 23-24 “the molten steel temperature after the denitrification treatment is set”.
Applicant persuasively argues revising “after” to “during” (p. 5 para. 3).
The molten steel temperature is set for denitrification, not after, where in applicant’s [0031] the set molten steel temperature is that required to reduce the nitrogen.
Claim 1 lines 26-27 “the molten steel temperature after the denitrification treatment”.
The molten steel temperature is for denitrification. In applicant’s [0031] the molten steel temperature is that required to reduce the nitrogen.
Claim 1 line 27 “5°C or more”.
Applicant persuasively argues support in [0031] (p. 5 para. 4).
[0031] recites “the temperature Tf of the molten steel is increased by 5°C or more each time the MgO concentration (MgO) in the slag increases by 1.0 mass%.”
The following 112(a) rejection is withdrawn due to claim cancellation:
Claim 19 line 2 “MgO…up to 17 mass %”.
The following 112(b) rejections are withdrawn due to claim amendment:
Claim 1 line 4 “metal-Al-containing substance”.
Claim 1 lines 10-12 “the furnace internal atmospheric pressure is at an atmospheric pressure of 105 Pa or at a lower depressurized atmospheric pressure”.
[0030] of applicant’s specification recites “a lower depressurized atmospheric pressure” being lower than 105 Pa.
Claim 1 line 23 “predetermined value”.
Claim 1 lines 23 and 26-27 “after the denitrification treatment”.
Claim 1 lines 26-28 “the molten steel temperature after the denitrification temperature corresponds to 5°C or more than the reference molten steel temperature for each 1.0 mass % of MgO in the slag”.
Claim 19 line 2 “MgO…up to 17 mass %”.
Claim 20 line 2 “MgO…up to 10 mass %”.
The applicant persuasively argues the issues are addressed by revising the claim 1 relationship in equation form (p. 7 para. 3).
Claim 22 lines 1-2 “the reference molten steel temperature is 1600°C”.
Withdrawn Double Patenting
The following nonstatutory double patenting rejection is withdrawn:
Claims 1-3, 7, 8, and 19-22 over claims 1-5 of U.S. Patent No. 12,252,754 (US ‘574, US App No 18/560,737) in view of Yamaguchi (JP H08-246024 machine translation).
A terminal disclaimer listing Patent # 12,252,754 was filed and approved July 13, 2026.
Response to Remarks filed August 3, 2026
112(a)
While the 112(a) rejections from the 5/5/2026 are withdrawn due to claim amendment (see above), the claim 1 amendments introduce a new 112(a) rejection as detailed below.
112(b)
Applicant's arguments filed August 3, 2026 with respect to the 112(b) rejection of claim 1 lines 26-28 and the reference molten steel temperature have been fully considered but they are not persuasive.
The applicant argues amended claim 1 recites Tref, which, in the context of Fig. 8, corresponds to the y-intercept (p. 6 para. 6).
It is important not to import into a claim limitations that are not part of the claim. For example, a particular embodiment appearing in the written description may not be read into a claim when the claim language is broader than the embodiment. MPEP 2111.01(III).
Claim 1 recites Tref, which is not limited to the 1600°C y-intercept of Fig. 8. It is unclear what the metes and bounds are of the claimed reference molten steel temperature, Tref. It is unclear if there is only one reference temperature at which denitrification treatment would be performed when there is no MgO in the slag. If there are multiple possible temperatures, then Tref would be multiple values, such that Tf would vary based on the chosen Tref, making the metes and bounds of the claim unclear. The composition of the slag beyond requiring “no MgO” is not specified. Therefore, it is unclear how to determine a reference temperature given that it is unclear what the reference temperature is relative to.
Therefore, the 112(b) rejection regarding Tref is maintained.
Yamaguchi in view of Kundrat and Suk; Yamaguchi in view of Kundrat, Suk, and Zhao
Applicant's arguments filed August 3, 2026 with respect to Yamaguchi in view of Kundrat and Suk and Yamaguchi in view of Kundrat, Suk, and Zhao have been fully considered but they are not persuasive.
The applicant argues none of the cited references control the temperature of the molten steel based on the MgO content of the slag because Kundrat adjusts the slag basicity to prevent making the slag viscous due to an increased liquidus temperature (para. spanning pp. 7-8) and Suk discloses a low-melting point slag of 1400 to 1550°C by adding a low melting point flux to more easily absorb titanium nitride (TiN) inclusions while making titanium-containing austenitic stainless steel and is not relevant to oxygen blowing procedures to reduce nitrogen (p. 8 para. 3) such the “general conditions” of the claim are not disclosed (para. spanning pp. 8-9).
The pending rejections are over the combination of Kundrat and Suk. Kundrat discloses that for CaO-Al2O3-MgO-slags high concentrations of MgO increase the liquidus temperature, making a viscous slag that is difficult to mix with the metal bath (10:36-37, 14:1-5). Suk discloses maintaining a liquid state slag more easily absorb inclusions, such as nitrogen, for improved cleanliness (Sun [0010], [0024], [0029]-[0030], Fig. 3). Therefore, one of ordinary skill in the art would understand that when adding MgO to slag the liquidus temperature increases and it is advantageous to maintain a liquid state slag by increasing the temperature for improved inclusion absorption.
While Kundrat may prevent a viscous slag by adjusting basicity, Kundrat in view of Suk also discloses MgO increases the slag liquidus temperature and the benefits to maintaining a liquid state slag for inclusion absorption.
While Suk may be directed to a low-melting point slag and absorbing TiN inclusions, Suk’s disclosure that “inclusions can be easily absorbed into the liquid…slag” is not limited to only the low-melting point slag of Suk nor TiN inclusions. Further, contrary to applicant’s arguments, Suk discloses denitrification (removal of nitrogen from the molten steel) using a low-melting slag prevents the formation of TiN ([0024]).
Yamaguchi and Suk are in the same field of endeavor of applicant’s claimed molten steel denitrification method (Yamaguchi [0001]; Suk [0010], [0024]).
Kundrat is also reasonably pertinent to the problem faced by the inventor of a CaO-Al2O3-MgO-containing slag during molten steel removal of impurities with increasing MgO concentration increasing slag basicity, which increases slag viscosity and liquidus temperature (Kundrat 10:34-40, 13:53-55, 14:1-5; applicant’s claim 1; applicant’s specification [0015], [0031], Fig. 8). Therefore, Kundrat is proper for use in an obviousness rejection under 35 U.S.C. 103. MPEP 2141.01(a)(I).
For the above cited reasons the rejections of Yamaguchi in view of Kundrat and Suk and of Yamaguchi in view of Kundrat, Suk, and Zhao are maintained.
Claim Interpretation
Claim 1 lines 6-7 “a step of adding a CaO-containing substance separately or together with an MgO-containing substance” is interpreted as the step requiring 1) addition of a CaO-containing substance and, separately, a MgO-containing substance, or 2) addition of a CaO- and MgO-containing substance.
Claim 1 line 26 “the slag” is given the broadest reasonable interpretation of referring to line 3 “a CaO-and-Al2O3-and MgO-containing slag”.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-3, 7, 8, and 19-22 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement.
The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 1 lines 15-17 “during the denitrification treatment, Tf in °C, is set according to the following equation: Tf ≥ 5*[MgO] + Tref” fails to comply with the written description requirement.
In Applicant’s Remarks filed August 3, 2026, the applicant argues support in [0031], Fig. 8, and original claim 6 (para. spanning pp. 4-5).
Applicant’s [0031] and original claim 6 recite “temperature Tf of the molten steel…is increased by 5°C or more each time…MgO concentration (MgO) in the slag increases by 1.0 mass%”. Applicant’s original language does not mention the increase in temperature relative to a reference temperature, Tref. It also only supports a temperature increase of 5°C or more for 1.0 mass% increases of MgO in the slag. While applicant has support for this claim language, as previously discussed (5/5/2026 Non-Final Rejection para. spanning pp. 10-11) it introduces a 112(b) rejection. It is unclear how much MgO is required to be added, if the MgO is required to be added in 1 mass% increments, what the starting MgO concentration is, and whether or not this limitation recites a property.
Applicant’s Fig. 8 presents the equation “Tf = 5.1449(MgO) + 1600”. This Fig. 8 equation is different than the claimed equation, such that the claimed equation is not supported. In Fig. 8 the multiplier on the (MgO) is 5.1449, not 5. The equation in Fig. 8 has a y-intercept of 1600, whereas the claimed equation more broadly recites “Tref”. The Fig. 8 equation has an equal sign, whereas the claimed equation uses a greater than or equal to sign.
Therefore, applicant’s disclosure in the specification as originally filed does not support the above cited claim limitation.
Claims 2, 3, 7, 8, and 20-22 are rejected as depending from claim 1.
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 1-3, 7, 8, and 19-22 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.
Claim 1 lines 18-23 “Tref is a reference molten steel temperature, in °C, that would be required to reduce the nitrogen concentration in the molten steel to the value that is less than or equal to 35 ppm with the denitrification treatment when there is no MgO in the slag” renders the claim indefinite. It is unclear what the metes and bounds are of the claimed reference molten steel temperature. It is unclear if there is only one reference temperature at which denitrification treatment would be performed when there is no MgO in the slag. If there are multiple possible temperatures, then Tref would be multiple values, such that Tf would vary based on the chosen Tref, making the metes and bounds of the claim unclear. The composition of the slag beyond requiring “no MgO” is not specified. Therefore, it is unclear how to determine a reference temperature given that it is unclear what the reference temperature is relative to.
Claims 2, 3, 7, 8, and 20-22 are rejected as depending from claim 1.
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 1-3, 7, 8, and 20-22 are rejected under 35 U.S.C. 103 as being unpatentable over Yamaguchi (JP H08-246024 machine translation) in view of Kundrat (US 5,749,939) and Suk (KR 2012-0072822 machine translation).
Regarding claim 1, Yamaguchi discloses a molten steel denitrification method ([0001]) carried out in a furnace ([0024]), the method comprising:
forming a CaO-and-Al2O3-and MgO-containing slag ([0008], [0017]) by a combination of a step of adding an Al-containing molten steel ([0009], [0020], [0024]) having a concentration of Al that is in a range of 0.1 to 1.0 mass% ([0018]-[0020]: [Al]>= 0.3 wt%), and a step of adding a CaO-containing substance separately or together with an MgO-containing substance to the molten steel (dolomite is CaMg(CO3)2) ([0017], [0024]-[0025]), and
then blowing an oxygen-containing gas from above and onto the slag to perform a denitrification treatment ([0008]), wherein during the denitrification treatment, the furnace internal atmospheric pressure is at a pressure of 105 Pa or lower (reduced pressure) ([0021]),
wherein a mass ratio of CaO to Al2O3 in the slag is in a range of from 0.4 to 1.8 ([0017]: 35-65 wt% CaO and 30-55 wt% Al2O3 results in a CaO/Al2O3 ratio of 0.64 to 2.17),
wherein the denitrification treatment reduces the nitrogen concentration in the molten steel to a value that is less than or equal to 35 ppm (denitrification to extremely low nitrogen range, such as N ≤ 40 ppm in the molten steel or N < 20 ppm) ([0001]-[0002], [0007], [0013], [0026]-[0031], Fig. 1).
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. MPEP 2144.05(I).
Yamaguchi is silent to the molten steel temperature during the denitrification treatment, Tf in °C, being set according to the following equation: Tf ≥ 5*[MgO] + Tref where [MgO] is the concentration of MgO in the slag in mass %, and Tref is a reference molten steel temperature, in °C, that would be required to reduce the nitrogen concentration in the molten steel to the value that is less than or equal to 35 ppm with the denitrification treatment where there is no MgO in the slag.
Kundrat discloses a CaO-and-Al2O3-and MgO-containing slag (10:23-26, 13:46-49, 59-67, 14:1-11) where each time the MgO concentration in the slag is increased the slag liquidus temperature increases (10:34-40, 13:53-55, 14:1-5).
Suk discloses a denitrification process to remove nitrogen from molten steel using a slag in the liquid state ([0010], [0024]).
It would have been obvious to one of ordinary skill in the art in the process of Yamaguchi to increase the temperature of the molten steel based on addition of MgO because adding MgO increases the slag liquidus temperature (Kundrat 10:34-30, 13:53-55, 14:1-5), which may result in trapped droplets of the alloy in the slag (Kundrat 10:34-40) and it makes the slag viscous and difficult to mix (Kundrat 14:1-5), whereas a liquid state slag (Suk [0020]) that covers the molten steel (Suk [0019]) easily absorbs inclusions, improving the cleanliness of the steel (Suk [0010]), including nitrogen removal (Suk [0029]-[0030], Fig. 3).
Therefore, Yamaguchi in view of Kundrat and Suk discloses the molten steel temperature during the denitrification treatment, Tf, is set (increased) relative to a reference molten steel temperature that would be required to reduce the nitrogen concentration in the molten steel to the value that is less than or equal to 35 ppm with the denitrification treatment when there is no MgO in the slag, Tref (Kundrat 10:34-40, 13:53-55, 14:1-5; Suk [0010], [0019], [0020], [0029]-[0030]: liquid state slag covers the molten steel, easily absorbing inclusions, including nitrogen, and improving the cleanliness of the steel). With respect to Tf ≥ 5*[MgO} + Tref, “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” MPEP 2144.05(II)(A).
The limitation of “T.Fe in the slag after denitrification is set to 3.0 mass% or lower” has been considered and determined to naturally flow from the claimed denitrification process. The prior art discloses a denitrification process that is substantially similar to that claimed, including adding Al, CaO-containing substance, and MgO-containing substance to molten steel (Yamaguchi [0009], [0017], [0020], [0024]-[0025]), denitrifying by “blowing an oxidizing gas onto the surface of the slag so that the gas does not come into direct contact with the molten metal” (Yamaguchi [0008]), and overlapping Al concentration, pressure, and CaO/Al2O3 mass ratio for the slag (Yamaguchi [0017]-[0021]), such that “T.Fe in the slag after denitrification is set to 3.0 mass% or lower” naturally flows from the disclosure of the prior art. Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” MPEP 2144.05(II)(A).
Regarding claim 2, Yamaguchi discloses in the denitrification treatment, the oxygen-containing gas is supplied such that a ratio Ls/Ls0 between a thickness Ls0 of the slag and a depth Ls of a depression in the slag resulting from blowing of the oxygen-containing gas becomes 0.9 or lower ([0008]: oxidizing gas blown onto the surface of the slag so that the gas does not come into direct contact with the molten metal reads on Ls/Ls0 of less than 1).
For Ls/Ls0 of less than 1, in the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. MPEP 2144.05(I).
For the blown oxidizing gas not coming into direct contact with the molten metal, “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” MPEP 2144.05(II)(A).
Regarding claims 3 and 8, Yamaguchi discloses in the denitrification treatment, the oxygen-containing gas is an O2 gas diluted with an inert gas other than an N2 gas ([0021]: mixing O2 with Ar).
Regarding claim 7, Yamaguchi in view of Kundrat and Suk and optionally Fujimoto discloses a steel production method wherein molten steel smelted by the molten steel denitrification method according to claim 1 (see claim 1 rejection) is cast (Yamaguchi [0006]).
Regarding claim 20, Yamaguchi in view of Kundrat and Suk discloses MgO is present in the slag at a concentration of up to 10 mass % (10 and 20 wt%) (Kundrat 10:40, 13:66 to 14:5). In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. MPEP 2144.05(I).
Regarding claim 21, Yamaguchi in view of Kundrat and Suk discloses MgO is present in the slag at a concentration in a range of from 5 to 10 mass % (10 and 20 wt%) (Kundrat 10:40, 13:66 to 14:5). In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. MPEP 2144.05(I).
Regarding claim 22, Yamaguchi in view of Kundrat and Suk discloses Tref is 1600°C (at least 1500°C, preferably between 1500 and 1750°C, with examples at 1600°C) (Kundrat 9:15-18, 10:15-22, 17:40 to 18:57, Tables V-VI).
Claims 1-3, 7, 8, and 20-22 are rejected under 35 U.S.C. 103 as being unpatentable over Yamaguchi (JP H08-246024 machine translation) in view of Kundrat (US 5,749,939), Suk (KR 2012-0072822 machine translation), and Zhao (CN 113373278 machine translation).
In the event it is determined that the T.Fe in the slag after denitrification being set to 3.0 mass% or lower does not naturally flow from the disclosure of Yamaguchi in view of Kundrat and Suk, then the below rejection including Zhao is applied.
Regarding claim 1, Yamaguchi discloses a molten steel denitrification method ([0001]) carried out in a furnace ([0024]), the method comprising:
forming a CaO-and-Al2O3-and MgO-containing slag ([0008], [0017]) by a combination of a step of adding an Al-containing molten steel ([0009], [0020], [0024]) having a concentration of Al that is in a range of 0.1 to 1.0 mass% ([0018]-[0020]: [Al]>= 0.3 wt%), and a step of adding a CaO-containing substance separately or together with an MgO-containing substance to the molten steel (dolomite is CaMg(CO3)2) ([0017], [0024]-[0025]), and
then blowing an oxygen-containing gas from above and onto the slag to perform a denitrification treatment ([0008]), wherein during the denitrification treatment, the furnace internal atmospheric pressure is at a pressure of 105 Pa or lower (reduced pressure) ([0021]),
wherein a mass ratio of CaO to Al2O3 in the slag is in a range of from 0.4 to 1.8 ([0017]: 35-65 wt% CaO and 30-55 wt% Al2O3 results in a CaO/Al2O3 ratio of 0.64 to 2.17),
wherein the denitrification treatment reduces the nitrogen concentration in the molten steel to a value that is less than or equal to 35 ppm (denitrification to extremely low nitrogen range, such as N ≤ 40 ppm in the molten steel or N < 20 ppm) ([0001]-[0002], [0007], [0013], [0026]-[0031], Fig. 1).
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. MPEP 2144.05(I).
Yamaguchi is silent to the molten steel temperature during the denitrification treatment, Tf in °C, being set according to the following equation: Tf ≥ 5*[MgO] + Tref where [MgO] is the concentration of MgO in the slag in mass %, and Tref is a reference molten steel temperature, in °C, that would be required to reduce the nitrogen concentration in the molten steel to the value that is less than or equal to 35 ppm with the denitrification treatment where there is no MgO in the slag.
Kundrat discloses a CaO-and-Al2O3-and MgO-containing slag (10:23-26, 13:46-49, 59-67, 14:1-11) where each time the MgO concentration in the slag is increased the slag liquidus temperature increases (10:34-40, 13:53-55, 14:1-5).
Suk discloses a denitrification process to remove nitrogen from molten steel using a slag in the liquid state ([0010], [0024]).
It would have been obvious to one of ordinary skill in the art in the process of Yamaguchi to increase the temperature of the molten steel based on addition of MgO because adding MgO increases the slag liquidus temperature (Kundrat 10:34-30, 13:53-55, 14:1-5), which may result in trapped droplets of the alloy in the slag (Kundrat 10:34-40) and it makes the slag viscous and difficult to mix (Kundrat 14:1-5), whereas a liquid state slag (Suk [0020]) that covers the molten steel (Suk [0019]) easily absorbs inclusions, improving the cleanliness of the steel (Suk [0010]), including nitrogen removal (Suk [0029]-[0030], Fig. 3).
Therefore, Yamaguchi in view of Kundrat and Suk discloses the molten steel temperature during the denitrification treatment, Tf, is set (increased) relative to a reference molten steel temperature that would be required to reduce the nitrogen concentration in the molten steel to the value that is less than or equal to 35 ppm with the denitrification treatment when there is no MgO in the slag, Tref (Kundrat 10:34-40, 13:53-55, 14:1-5; Suk [0010], [0019], [0020], [0029]-[0030]: liquid state slag covers the molten steel, easily absorbing inclusions, including nitrogen, and improving the cleanliness of the steel). With respect to Tf ≥ 5*[MgO} + Tref, “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” MPEP 2144.05(II)(A).
Yamaguchi is silent to T.Fe in the slag after denitrification being set to 3.0 mass% or lower.
Zhao discloses molten steel with a CaO-and-Al2O3-and MgO-containing slag ([n0008], [n0010]) wherein T.Fe in the slag after the denitrification treatment is set to 3.0 mass% or lower ([n0012]).
It would have been obvious to one of ordinary skill in the art in the process of Yamaguchi to control the T.Fe in the slag after denitrification to 3.0 mass% or lower to ensure that the slag surface deoxidizer fully melts and reacts with the original oxidizing slag, and then significantly reduces the oxidizing properties of the slag (Zhao [n0016]).
Regarding claim 2, Yamaguchi discloses in the denitrification treatment, the oxygen-containing gas is supplied such that a ratio Ls/Ls0 between a thickness Ls0 of the slag and a depth Ls of a depression in the slag resulting from blowing of the oxygen-containing gas becomes 0.9 or lower ([0008]: oxidizing gas blown onto the surface of the slag so that the gas does not come into direct contact with the molten metal reads on Ls/Ls0 of less than 1).
For Ls/Ls0 of less than 1, in the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. MPEP 2144.05(I).
For the blown oxidizing gas not coming into direct contact with the molten metal, “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” MPEP 2144.05(II)(A).
Regarding claims 3 and 8, Yamaguchi discloses in the denitrification treatment, the oxygen-containing gas is an O2 gas diluted with an inert gas other than an N2 gas ([0021]: mixing O2 with Ar).
Regarding claim 7, Yamaguchi in view of Kundrat and Suk and optionally Fujimoto discloses a steel production method wherein molten steel smelted by the molten steel denitrification method according to claim 1 (see claim 1 rejection) is cast (Yamaguchi [0006]).
Regarding claim 20, Yamaguchi in view of Kundrat and Suk discloses MgO is present in the slag at a concentration of up to 10 mass % (10 and 20 wt%) (Kundrat 10:40, 13:66 to 14:5). In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. MPEP 2144.05(I).
Regarding claim 21, Yamaguchi in view of Kundrat and Suk discloses MgO is present in the slag at a concentration in a range of from 5 to 10 mass % (10 and 20 wt%) (Kundrat 10:40, 13:66 to 14:5). In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. MPEP 2144.05(I).
Regarding claim 22, Yamaguchi in view of Kundrat and Suk discloses Tref is 1600°C (at least 1500°C, preferably between 1500 and 1750°C, with examples at 1600°C) (Kundrat 9:15-18, 10:15-22, 17:40 to 18:57, Tables V-VI).
Related Art
Tada (US 2009/0019968)
Tada discloses a molten steel denitrification method ([0001], [0019]) in which CaO-and-Al2O3-containing slag ([0064], [0085]) is formed by a combination of an Al addition step of adding a metal-Al-containing substance to molten steel to deoxidize and turn the molten steel into Al-containing molten steel ([0077]-[0081]) and a CaO addition step of adding CaO-containing substance to the molten steel ([0077], [0082]-[0084]), and then an oxygen-containing gas is blown from above and through the slag to perform a denitrification treatment ([0088]-[0091]) without using carbide denitrification flux ([0077]-[0087]), wherein the Al concentration is adjusted to a predetermined range in the Al addition step ([0078]), the atmospheric pressure in the furnace during the denitrification process is adjusted to a predetermined range ([0028], [0055], [0057], [0092]-[0100]), the mass ratio C/A of CaO/Al2O3 is within a predetermined range for the slag composition ([0084]).
Numata (US 2013/084205)
Numata discloses a slag with not less than 40% CaO, not less than 5% MgO, and total content of Fe oxides and Mn oxides of not more than 3% ([0091]), where limiting the Fe oxides and Mn oxides subjects the slag to reducing reaction and prevents an issue with oxygen activity at the slag-metal interface ([0094]). Numata also discloses the content of Al in the molten steel is about 0.01 to 0.05% ([0097]).
Kim (KR 2013-0034253 machine translation)
Kim discloses a flux for steelmaking that reduces the T.Fe in the slag ([0001]) by adding Mg, which generates oxidation reaction heat ([0005]). Kim also discloses that steel properties deteriorate due to non-metallic inclusions, where preventing molten melt from coming into contact with the atmosphere prevents molten metal oxidation ([0002]). Kim also discloses flux covering molten metal prevents directed contact between molten metal and the atmosphere ([0003]).
Yonezawa (JP H11-269524 machine translation)
Yonezawa discloses pretreatment of molten iron ([0001]) so that the T.Fe content of the slag is 3% to 20% ([0011]) to increase the degree of oxidation of the slag and keep the molten iron temperature low ([0013]) and to achieve sufficient dephosphorization reaction ([0022]).
Zhao (CN 113373278 machine translation)
Zhao discloses a slag modification process ([n0001], [n0005]) using slag that includes 40 to 50% CaO and 15 to 25% Al2O3 (CaO/Al2O3, C/A, is 1.6 to 3.3, 40/25 to 50/15) ([n0008], [n0010]) with a T.Fe in the ladle slag below 3% ([n0012]) to significantly reduce the oxidizing properties of the slag by fully melting and reacting the original oxidizing ladle slag ([n0016]).
Ban-Ya (US 2011/0167960)
Ban-Ya discloses a flux (slag) for refining steel of low nitrogen ([0002]) with 5 to 17% MgO ([0009]) and a refining temperature of approximately 1600°C ([0016], [0042], Table 3).
Conclusion
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.
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/STEPHANI HILL/Examiner, Art Unit 1735
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