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 .
Response to Amendment and Status of Claims
Applicant’s amendments to the claims, filed April 16, 2026, are acknowledged. Claim 1 is amended and Claims 2-3 are cancelled. No new matter has been added.
Claims 1 and 4 are pending and currently considered in this office action.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on February 13, 2026 was filed after the mailing date of the Non-Final Rejection on January 16, 2026. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
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.
Claim 1, and dependent Claim 4, 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 recites the limitation "wherein in the preparing, the dolomite is pulverized such that a Blaine specific surface area is greater than or equal to 6,000cm2/g, and/or the dolomite is calcined at a temperature greater than or equal to 900C". The usage of “and/or” causes the claim to be unclear as to whether or not both the claimed Blaine surface area and calcination at 900C are required, or if only one of the limitations is needed to satisfy the claim requirements. Additionally, it is unclear if ‘the dolomite is calcined at a temperature greater than or equal to 900C’ is an inclusion of ‘the preparing’ or not.
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 1 and Claim 4 are rejected under 35 U.S.C. 103 as being unpatentable over Yasuda (previously cited and cited by Applicant in IDS filed December 22, 2023, US 20100206131 A1) in further view of Kreiger (previously cited, US 4004916 A), Sakamoto (previously cited, JP 2008127636 A, English Machine Translation provided) and Zhang (US 20170183760 A1).
Regarding Claim 1 and Claim 4, Yasuda discloses a method for producing iron ore pellets for operation of a blast furnace (Abstract; para. [0002]; para. [0012]),
wherein the iron ore pellets have a CaO/SiO2 mass ratio of 0.8 or more and a MgO/SiO2 mass ratio of 0.4 or more (Abstract; see Table 1 C/S (CaO/SiO2) and M/S (MgO/SiO2) values), the method comprising:
balling green pellets by adding water to an iron ore material and dolomite (para. [0036]-[0037]; pelletizing reads on the balling; raw pellets read on green pellets as claimed; see also para. [0005] and para. [0022] regarding dolomite), and
firing the green pellets at a temperature of 1220-1300C, which reads on (Claim 4) the claimed temperature of 1250C or more (para. [0038]).
Yasuda discloses preparing the dolomite by ball milling to impart miniaturization, wherein the auxiliary raw materials (dolomite) is ball milled before or after blending such that 80% or more particles comprise a grain size of 44um or less, which overlaps and reads on the claimed miniaturized state of the dolomite wherein 45vol% or more particles have a grain size of less than or equal to 20um after balling (para. [0036]; 44um or less reads on 20um or less).
Yasuda however fails to disclose wherein pulverization achieves the claimed Blaine specific surface area.
Kreiger teaches wherein fume (raw pulverized material mixture to be balled for green iron ore pellet) conventionally comprises a size of 0.1-25um, wherein 90% of particles are less than 25um (Col. 1, lines 35-39; Table 1, wherein raw material comprises MgO and CaO; dolomite comprises MgO and CaO), and wherein the fume comprises a Blaine surface area of 8,000-12,000 cm2/g in order to successfully ball the material into strong agglomerates (Col. 5, lines 39-48).
Sakamoto teaches wherein the Blaine surface area indicates particle size, and that the Blaine surface area may easily be tailored by changing the degree of pulverization and therefore particle size (para. [0023]; para. [0045]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have pulverized the fume (dolomite) to comprise particles wherein 90% comprise a grain size of less than 25um, which overlaps the claimed range of 45vol% or more particles having a particle size of 20um or less, and to have comprised a Blaine surface area of 8,000-12,000 cm2/g for the granulated materials forming the green pellet, including the MgO and CaO containing materials and therefore the dolomite of Yasuda, which reads on the claimed range of 6,000cm2/g or more, as taught by Kreiger, for the invention disclosed by Yasuda, in order to successfully ball the material into strong green agglomerates and because these particle sizes are conventional, well-known and suitable for the production of iron ore pellets (see teaching above). Additionally, it would be obvious that acquiring a Blaine specific surface area of 8000-12000cm2/g would produce the claimed grain sizes because Sakamoto teaches that the specific surface area indicates the particle (grain) size (see teaching above). Therefore, the claimed grain size of the dolomite particles and the claimed Blaine specific surface area of the pulverized dolomite have been met.
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). See MPEP § 2144.05.I.
Yasuda teaches wherein dolomite is used as a CaO and MgO source (para. [0002]; para. [0014]), and further discloses drying and pre-heating the pellets (para. [0038]). However, Yasuda is silent towards calcining the dolomite during preparation at 900C or higher.
Zhang teaches wherein pellets including dolomite are dried and calcined from 850-1050C, prior to high-temperature firing (reduction), in order to remove moisture, volatile matter and to decompose carbonates, thereby generating MgO which is required for the high temperature reduction process (para. [0007]; para. [0013]-[0016]). The high temperature reduction process of Zhang corresponds to the firing step of Yasuda, which reduces the pellets, and the processing of the dolomite is substantially the same function in Zhang as it is in Yasuda.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have calcined the dolomite at a temperature of 850-1050C, which reads on the claimed range of 900C or more, as taught by Zhang, for the invention disclosed by Yasuda, in order to remove moisture, volatile matter and to decompose carbonates, thereby generating the MgO which is required for the high temperature firing (reduction) process (see teachings above). Examiner notes that the balling step may be considered a part of preparing the dolomite, as the claims as currently written do not differentiate between the two steps.
In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). See MPEP § 2144.05.I.
Response to Arguments
Applicant’s arguments, filed April 16, 2026, with respect to Claim 1, and dependent claims thereof, rejected under 35 U.S.C. 102(a)(1) over Yasuda, have been fully considered and are persuasive in view of Applicant’s amendments to the claims which incorporate the contents of previous Claim 2 and Claim 3 into independent Claim 1, and further limit the Blaine specific surface area to 6,000 cm2/g or greater and further limit the dolomite grain size. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of Yasuda in view of Kreiger, Sakamoto and Zhang, as detailed above.
Arguments directed to Valenti, Hedley, and the Blaine specific surface area teachings of Sakamoto, are deemed moot in view of the new ground(s) of rejection.
Regarding Kreiger:
Applicant argues that Kreiger is directed to the transportation and storage of moist agglomerates and is based on the premise that the pellets will not be sintered.
This argument is not found persuasive.
Kreiger appears to only teach away from sintering as the method for increasing pellet strength, which is different than the firing of Yasuda whom discloses firing as a means to provide self-fluxing pellets which have the correct composition for reducibility (para. [0034]). Kreiger teaches that tailoring the specific surface area achieves the needed strength for transportation, handling and storage, and the pellet formation of Kreiger is substantially the same as Yasuda, as both references pelletize the raw material with water. One of ordinary skill in the art would appreciate the benefit of strengthening the green agglomerates for transportation, storage and handling, including processing stages involving transportation, storage and handling prior to firing and/or prior to charging. Thus, the teaching of Kreiger is compatible with Yasuda as increased strength of the green pellet prior to firing would still be desirable.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Paul (US 3397070 A): teaches calcining dolomite at 3300F (about 1815C) or greater in order produce a dolomite grain with at least 98% MgO.CaO and having a hydration susceptibility of less than 5% (Abstract).
Ferraris (previously cited, “Identifying improved standardized tests for measuring cement particle size and surface area”): Ferraris teaches wherein the fineness of a particle is proportional to the Blaine surface area, and teaches wherein a particle d90 size of 17.4um comprises a Blaine surface area of 5450 cm2/g (545 m2/kg) (Pg. 4, lines 10-12; Pg. 9, Table 1). One of ordinary skill in the art would therefore appreciate that a Blaine surface area of 8000-1200 cm2/g (see teaching by Kreiger) would comprise a d90 size of 20um or less, as claimed.
Sakamoto (previously cited and applied above, JP 2008127636 A, English Machine Translation, further teachings): teaches a mixture of raw material comprising dolomite which has a Blaine surface area of 4,300 cm2/g and is therein mixed with other components with much smaller Blaine surface areas in order to comprise an optimum Blaine surface area for the final mixture, thereby improving the strength of the pellet formed while preventing bursting (Abstract; para. [0033]; para. [0035], post grinding raw material A including dolomite; para. [0036]; Table 1, see inventive case (c) for example).
Valenti (previously cited, US 4497661 A): teaches wherein dead-burned or calcined dolomite may have a MgO content of 80% or more as the MgO source (Abstract; Col. 6, line 41-42 and line 48; Col. 9, lines 17-52).
Hedley (previously cited, GB 2042499 A): teaches a stable dead-burned dolomite useful as a refractory material which has low resistance to chemical attack and tendency of hydration (Pg. 1, lines 5-15; Pg. 2, lines 14-19). Hedley teaches wherein the dead-burned product comprises 40-90% MgO and is formed using a dead-burning temperature of 1350-2000C (Pg. 1, lines 42-44; Pg. 2, lines 8-11).
Stein (US 20180187276 A): teaches wherein dead burned dolomite refers to dolomite that has been calcined or dead burned at 1500-2000C, thereby forming MgO as periclase (para. [0025]).
Zhang604 (US 20230049604 A): teaches calcining dolomite and grinding to form a powder prior to pelletizing (para. [0079]-[0080]).
De Costa (US 20200190623 A1): teaches using semi-hydrated dolime, obtained by calcination and partial hydration of dolomite, in order to properly form metallic ore fluxed pellets which withstand the induration process, giving afterwards fired pellets of good quality, including good mechanical and good metallurgical properties (para. [0035]-[0036]; para. [0040]). De Costa teaches a d50 particle size of the semi-hydrated dolime to be 4-8um (para. [0060]).
Chemetall (“Determination of average particle size (according to Blaine)”): teaches that the particle size may be estimated by the Blaine specific surface area using the equation d=6/(p*S), wherein S is the Blaine specific surface area, p is density, and d is equivalent particle size. Dolomite has a density of 2.48g/cm3, therefore a Blaine specific surface area of 8000 cm2/g equates to a particle size of approximately 3um.
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 CATHERINE P SMITH whose telephone number is (303)297-4428. The examiner can normally be reached Monday - Friday 9:00-4:00 MT.
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CATHERINE P. SMITH
Patent Examiner
Art Unit 1735
/CATHERINE P SMITH/ Examiner, Art Unit 1735
/KEITH WALKER/ Supervisory Patent Examiner, Art Unit 1735
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