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 .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 07/31/2025 has been entered.
Election/Restrictions
Applicant’s election without traverse of group III (claims 15-17 and 19) in the reply filed on 11/20/2024 is acknowledged.
Response to Amendment
The amendment filed on 12/31/2025 has been entered. Claims 1-3, 6-10, 14-17, 19-23, 26-27, 31-32, and 34 are pending in the application. Applicant’s amendments to the claims have not introduced new matter and are supported in the specification in at least [0010], [0025]-[0026], [0035], and [0074]-[0080] of the instant specification.
Response to Arguments
Applicant’s arguments, see Pg. 7-9 filed 12/31/2025 with respect to claim 15, have been fully considered however are partially directed to limitations regarding a high specific surface area impurity, introduced in the amendment filed 12/31/2025, which postdates the final rejection mailed 07/31/2025.
Upon further search and consideration and as necessitated by the amendment, the 35 U.S.C. 103 rejection of 07/31/2025 is withdrawn and a new grounds of rejection is made under 35 U.S.C. 103 as being unpatentable over Sohara et.al. (US 2008/0053337A1) in view of Kinnarinen et.al., (“Removal of hazardous trace elements from green liquor dregs by mechanical separation methods”, Nordic Pulp & Paper Research Journal 2018; 33(3): 420–429) and Engdahl et al. (US6074521), with evidentiary support for the rejection of claim 15 provided by Miglierini, “ How carbon dioxide can support the optimization of papermaking process”, Paper Industry World, 18 July 2017).
Applicant's remaining arguments on Pg. 7-9, filed 12/31/2025, have been fully considered but they are not persuasive.
Applicant argues on Pg. 8 that Applicant maintains that the claimed range of about 10 to about 11 is distinct from less than 9.5 and that a skilled person would not modify Sohara to use a pH above 9.5.
However, as previously stated, it is the position of the office that a teaching of “about 9.5” is interpreted as meeting the claimed limitation of “about 10 to about 11” as was relayed previously in the rejection on page 4 as it is deemed to be a slight difference absent any evidence of unexpected results. With regard to Applicants argument that “the skilled person would not have combined the teachings of Kinnarinen on centrifugation with the process described in Sohara and applied the described centrifuging conditions in Kinnarinen to the Sohara process,” this is not persuasive. The test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981).
Applicant argues on Pg. 8 the separation technique of Sohara is significantly different from the claimed method and would not result in separation of impurities.
However, the separation technique claimed is centrifuging and Sohara further teaches lime mud suspension is centrifuged to generate dewatered lime mud solids, also known as “centrifuge paste” which can be further treated [0022]-[0023].
Applicant argues on Pg. 8 Sohara obtains a suspension from the removal of grit/particles and that the suspension is further processed and a paste is not recovered. Applicant argues the dewatering step of Sohara cannot be equated to the claimed centrifugation step, as it is not of a first slurry.
However, the process of Sohara can be summarized as a screening of a lime mud suspension through a screen to provide a lime mud suspension that is then treated with CO2 to adjust the pH, this pH adjusted suspension is then subjected to filtration to provide a cake that is then collected and dispersed with a dispersant ([0040]). Additionally, the claim uses the term “comprising” which extends the scope of the claim and does not prohibit or exclude other steps from occurring. Accordingly, following the additional step in Sohara of performing a screening of the initial lime mud suspension, the subsequent method aligns with the claimed method. In response to applicant's argument that the references fail to show certain features of the invention, it is noted that the features upon which applicant relies (i.e., a first slurry) are not recited in the rejected claim. Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
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.
Claims 15-17 are rejected under 35 U.S.C. 103 as being unpatentable over Sohara et.al. (US 2008/0053337A1) in view of Kinnarinen et.al., (“Removal of hazardous trace elements from green liquor dregs by mechanical separation methods”, Nordic Pulp & Paper Research Journal 2018; 33(3): 420–429) and Engdahl et al. (US6074521), with evidentiary support for the rejection of claim 15 provided by Miglierini, “ How carbon dioxide can support the optimization of papermaking process”, Paper Industry World, 18 July 2017).
Regarding claim 15, Sohara teaches a process for producing precipitated calcium carbonate from lime mud (Abstract; [0011]). For the limitation “admixing a lime mud cake with water to form a first slurry”, Sohara teaches re-suspending lime mud solids in water to form a slurry [0024]. For the limitation “adjusting the pH of the first slurry to be about 10 to about 11”, Sohara teaches “The step 110 of neutralizing the lime mud suspension can be achieved by adding one or more nonmetal oxides. The nonmetal oxides react with water to produce sufficient acidity to react with and neutralize the excess alkalinity of the lime mud suspension due to the presence of alkaline compounds including, but not limited to, sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)) and the like. According to some embodiments, the one or more nonmetal oxides should be added in sufficient quantity so that the reaction produces a lime mud suspension pH of about 9.5 or less.” [0017] and “The screened lime mud suspension was then treated with gaseous CO2 having a concentration of 20 percent CO2 by volume in order to lower the pH from about 13 to about 9. Approximately 700 milliliters of the resulting neutralized lime mud suspension was then milled using a laboratory scale media mill” [0040]. Sohara teaches adjusting the pH to pH 9.5 and teaches the use of CO2 to lower the pH of the lime mud suspension. Evidentiary reference Miglierini notes that CO2 is used in papermaking as “an instrument to keep under control key process parameters – such as the pH and the concentration and dissolution of calcium carbonate (CaCO3) ) – and helps to stabilize the entire process” and shows, in Fig. 3, a plot of pH vs CO2 dosage. Accordingly, a person of ordinary skill in the art, when adjusting the pH of the lime mud suspension, would be have knowledge for how to meter in the correct amount of CO2 to adjust the pH of the lime mud suspension to pH 10.
Alternatively, Sohara discloses adjusting the pH to 9.5, while the present claims require a pH of about 10 to about 11. It is apparent, however, that the instantly claimed pH and that taught by Sohara are so close to each other that the fact pattern is similar to the one in In re Woodruff , 919 F.2d 1575, USPQ2d 1934 (Fed. Cir. 1990) or Titanium Metals Corp. of America v. Banner, 778 F.2d 775, 227 USPQ 773 (Fed.Cir. 1985) where despite a “slight” difference in the ranges the court held that such a difference did not “render the claims patentable” or, alternatively, that “a prima facie case of obviousness exists where the claimed ranges and prior art ranges do not overlap but are close enough so that one skilled in the art would have expected them to have the same properties”. In light of the case law cited above and given that there is only a “slight” difference between the pH of 9.5 disclosed by Sohara and the pH of “about 10” disclosed in the present claims, it therefore would have been obvious to one of ordinary skill in the art that the pH disclosed in the present claims is but an obvious variant of the pH disclosed in Sohara, and thereby one of ordinary skill in the art would have arrived at the claimed invention.
For the limitation “centrifuging the first slurry under conditions sufficient to achieve a g-force of about 500 to about 2000 g for a residence time of about 1 to about 10 minutes to obtain a centrate slurry comprising impurity particles and a paste comprising a purified calcium carbonate”, Sohara teaches the step of “separating large lime mud particles and/or grit particles from the lime mud suspension can be achieved through any of a variety of separation means including, but not limited to, screening, sedimentation, centrifugation, hydrocycloning or any combination thereof“ [0020]. Sohara further teaches lime mud suspension is centrifuged to generate dewatered lime mud solids, also known as “centrifuge paste” which can be further treated [0022]-[0023].
Sohara is silent on the g-force and the residence time.
Kinnarinen teaches “The rotational speed of the centrifuge and the centrifugation time were constant 2500 rpm and 120 s, respectively. The radius of the centrifuge rotor was 172 mm, so the maximum driving force of sedimentation, when the centrifuge was rotating at full speed, was 1200 G” [p.423, left column and Fig. 2]. The examiner notes that the residence time of 120 s is the same as 2 minutes. 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). In the instant case, the range taught by Kinnarinen (1200 G. 120 s) overlaps with the claimed range (about 500 to about 2000 g; 1 to about 10 minutes). Therefore, the range in Kinnarinen renders obvious the claimed range.
For the limitation “admixing the paste with water and a dispersant to form a dispersed slurry having a Brookfield viscosity of less than about 1000 cps at 100 rpm and containing the purified precipitated calcium carbonate”, Sohara teaches “In some embodiments, the washed lime mud solids can be diluted with water to provide a washed lime mud suspension having sufficient fluidity so as to be milled without a dispersant. In alternative embodiments, a dispersant may be added to the washed lime mud solids in an amount to provide sufficient fluidity to the washed lime mud solids so as to be milled as concentrated solids.” [0027] and “In some embodiments, the dispersant may be added to the washed lime solids before the milling process step. In other embodiments, the dispersant may be added during the milling process step to maintain sufficient fluidity to the washed lime mud solids during milling.” [0028] and “In some embodiments, a washed lime mud solids and/or suspension having a viscosity of about 1000 centipoise (as measured by a Brookfield Viscometer using a spindle speed of 100 rpm) or lower has sufficient fluidity for the milling process step.” [0029].
Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to advantageously modify the method of Sohara in view of Kinnarinen as evidenced by Miglierini to utilize the centrifuge parameters of Kinnarinen as applied to the method of Sohara. The teaching or suggested motivation for doing so being to successfully separate impurity particles from the lime mud to obtain a higher purity product of greater economic value.
The claim further requires “the lime mud cake contains one or more high specific surface area impurities” which are contained in the centrate slurry following centrifuging and are comprised of “one or more of silicates, calcium silicate hydrates, hydrotalcite-like compounds, calcium aluminates, calcium phosphates, and amorphous silicates.” Sohara does not explicitly discuss the impurities present in the lime mud or the presence in the centrate slurry following centrifuging.
Engdahl teaches a process for separating impurities from lime sludge to produce purified calcium carbonate (col. 3, lines 29-33; Fig. 1; Abstract). Lime sludge is described in Engdahl as being calcium carbonate produced from a causticizing reaction that is the reaction of Ca(OH)2 and Na2CO3 (col. 1, lines 32-50). This is the identical process as described in the instant specification (see [0004]) as producing “lime mud” and accordingly the lime sludge of Engdahl is equivalent to the “lime mud” in the instant invention.
Engdahl teaches the lime sludge contains sparingly soluble compounds including calcium phosphate, and calcium metasilicate (i.e. a silicate) (col. 3, line 2-col. 4, lines 35). Engdahl teaches the lime sludge containing the impurities is soaked with sodium carbonate to dissolve the impurities which allows for precipitation of the calcium carbonate (lime sludge) and removal of the impurities in the solution by separation by any method known per se (col. 4, lines 36-60). Engdahl further teaches the separation of the lime sludge precipitate from the solution comprising impurities can be performed by filtration methods including centrifugal separation (Claim 3; col. 6, lines 1-7).
Advantageously, treating lime sludge containing high specific surface area impurities such as calcium phosphate and calcium metasilicate allows for not only their removal from the lime sludge to provide a lime sludge with higher purity, but allows for treatment of the separation solution containing the impurities to allow for efficient recovery of useful chemicals (col. 3, lines 3-14).
Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to treat lime sludge containing calcium phosphate and calcium metasilicate impurities and separate the impurities via centrifugal separation to afford a filtrate containing the impurities in the process of Sohara in order to improve the purity of the calcium carbonate as well as efficiently recover other useful chemicals, as taught by Engdahl.
Regarding claim 16, modified Sohara teaches the method of claim 15, which further requires “further comprising milling the dispersed slurry to a median particle size of about 0.4 microns to about 5 microns”.
Sohara teaches “In some embodiments, the washed lime mud solids are milled to produce a final PCC material comprising PCC particles having a particle size distribution do value of about 4.0 micrometers or less. In other embodiments, the washed lime mud solids are milled to produce a final PCC material comprising PCC particles having a particle size distribution do value of about 2.0 micrometers or less. In further embodiments, the washed lime mud solids are milled to produce a final PCC material comprising PCC particles having a particle size distribution d50 value of from about 0.3 micrometers to about 4.0 micrometers. 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). In the instant case, the range taught by Sohara (0.3 to 0.4 microns) overlaps with the claimed range (about 0.4 to about 5 microns). Therefore, the range in Sohara renders obvious the claimed range.
As used herein, the term “particle size distribution d50 value” is defined as the numerical value, usually expressed in micrometers, at which 50 percent of the mass or volume fraction of particles have particle sizes that are less than or equal to that value.” [0026]. The examiner notes that “PCC” is “precipitated calcium carbonate” and that the d50 term is another way of stating “average “ or “mean” particle size.
Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to advantageously utilize the method of Sohara in view of Kinnarinen as evidenced by Miglierini to perform a milling step to provide a dispersed slurry with a median particle size about 0.4 microns to about 5 microns. The teaching or suggested motivation for doing so being to provide smaller more uniform particles of greater economic value and utility for use in papermaking.
Regarding claim 17, modified Sohara teaches the method of claims 15 and 16, and the claim further requires “further comprising adjusting the pH of the milled slurry to be about 9 to about 10.5 and/or adjusting the pH of the dispersed slurry to be about 9 to about 10.5”.
Sohara teaches “The screened lime mud suspension was then treated with gaseous CO2 having a concentration of 20 percent CO2 by volume in order to lower the pH from about 13 to about 9. Approximately 700 milliliters of the resulting neutralized lime mud suspension was then milled using a laboratory scale media mill” [0040]. The lime mud suspension of Sohara is a dispersed slurry. Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to advantageously utilize the method of Sohara in view of Kinnarinen as evidenced by Miglierini to perform a pH adjustment step to provide a milled slurry with a median particle size about 0.4 microns to about 5 microns. The teaching or suggested motivation for doing so being to provide a milled slurry with lesser caustic properties to minimize damage to process equipment.
Claim 19 is rejected under 35 U.S.C. 103 as being unpatentable over Sohara et.al. (US 2008/0053337A1) in view of Kinnarinen et.al., (“Removal of hazardous trace elements from green liquor dregs by mechanical separation methods”, Nordic Pulp & Paper Research Journal 2018; 33(3): 420–429) and Engdahl et al. (US6074521), and further in view of Omori et. al. (JP 2008115052A), as evidenced by Miglierini, “ How carbon dioxide can support the optimization of papermaking process”, Paper Industry World, 18 July 2017) and applied to claim 15.
Regarding claim 19, modified Sohara teaches the method of claim 15, which further requires “wherein the first slurry has a solids content of about 10% to about 25%”, to which Sohara, Kinnarinen, and Engdahl are silent.
Omori teaches, in example 1, “Next, water was added to the obtained dehydrated cake of lime sludge to form a slurry with a solid content concentration of 15%”. Omori teaches that the concentrated cake of lime sludge has a moisture content too low for the impurity-removal process step (in Omori, a floatation process) to be done, so the lime sludge cake was diluted to a concentration of 30 % by mass or less. Omori teaches the lime sludge cake must be diluted in order to have a suitable viscosity for the impurity-removal step to be successful ([Pg. 3, par. 8]). 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). In the instant case, the value taught by Omori (solid concentration of 15%) overlaps with the claimed range about 10% to about 25%). Therefore, the range in Omori renders obvious the claimed range.
Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to advantageously modify the method of modified Sohara in view of Omori to utilize the % solids taught by Omori as applied to the method of modified Sohara. The teaching or suggested motivation for doing so being to generate a lime mud slurry that has a % solids concentration and rheological properties that allows for successful impurity removal.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Taylor (US3347624); Taylor teaches a process of preparing calcium carbonate that includes preparing a suspension of calcium carbonate with a pH of about 8.5 or up to about 12 to precipitate calcium carbonate prior to filtration to remove by-products, and unreacted reactants (col. 1, line 62-col. 2, line 8).
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Jordan Wayne Taylor whose telephone number is (571)272-9895. The examiner can normally be reached Monday - Friday, 7:30 AM - 5 PM EST; Second Fridays Off.
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, Sally A. Merkling can be reached on (571)272-6297. 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.
/JORDAN W TAYLOR/Examiner, Art Unit 1738