Prosecution Insights
Last updated: October 25, 2026
Application No. 18/570,239

CARBONATION OF CALCIUM SULFATE CONTAINING MATERIALS

Final Rejection §103
Filed
Dec 14, 2023
Priority
Jul 15, 2021 — EU 21185792.5 +1 more
Examiner
GUINO-O UZZLE, MARITES A
Art Unit
1731
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Hsustainability GmbH
OA Round
2 (Final)
69%
Grant Probability
Favorable
3-4
OA Rounds
3m
Est. Remaining
86%
With Interview

Examiner Intelligence

Grants 69% — above average
69%
Career Allowance Rate
144 granted / 208 resolved
+4.2% vs TC avg
Strong +17% interview lift
Without
With
+16.6%
Interview Lift
resolved cases with interview
Typical timeline
3y 1m
Avg Prosecution
49 currently pending
Career history
264
Total Applications
across all art units

Statute-Specific Performance

§101
1.4%
-38.6% vs TC avg
§103
53.3%
+13.3% vs TC avg
§102
14.4%
-25.6% vs TC avg
§112
25.9%
-14.1% vs TC avg
Black line = Tech Center average estimate • Based on career data from 208 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 . Response to Amendment In response to the amendment received on 07/16/2026: claims 1-22 are currently pending; the 112(b) rejections to claims 3 and 7 are withdrawn in light of the amendment to the claims; and all prior art grounds of rejection are withdrawn in light of the amendment “and/or sulfide” in independent claim 1; however, new grounds of rejection are presented based on the same references as set forth herein. Claim Rejections - 35 USC § 103 The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. Claims 1-22 are rejected under 35 U.S.C. 103 as being unpatentable over Kendall et al. (US 20130195747 A1) (“Kendall” hereinafter). Regarding claim 1, Kendall teaches a method for sequestering carbon dioxide (see Kendall at [0003] teaching a method of making a composition, comprising a) contacting an industrial waste gas stream comprising carbon dioxide) comprising providing a starting material comprising calcium ions, sulfate… sulfite.. ions, and alkali metal ions (see Kendall at [0006] teaching a method, comprising: a) preparing a first composition comprising Na2CO3, NaHCO3, or a mixture thereof; b) adding calcium sulfate to the first composition, see Kendall at [0030] teaching as illustrated in FIG. 2, the SOx gas from flue gas may be subjected to flue gas desulfurization producing calcium sulfite which after hydration may form calcium sulfate). The first composition comprising Na2CO3, NaHCO3, or a mixture thereof is taken to meet the claimed alkali metal ions, and calcium sulfate/sulfite are taken to meet the claimed calcium ions, sulfate and sulfite ions, with a molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 > 2.00 (specification at [0013] discloses that [Symbol font/0x53] Alk is the sum of soluble alkali metal ions, and [Symbol font/0x53] SO3 is the sum of sulfate or sulfite ions, see Kendall at [0028]-[0029] teaching calcium sulfate source may include, but is not limited to… flue gas desulfurization… for example, in some embodiments, SO2 may be absorbed in a solution as sulfite, see Kendall at [0006] teaching in some embodiments, the calcium sulfate is a powder, see Kendall at [0057] teaching there are provided methods for making a composition, comprising a) contacting an industrial waste gas stream comprising carbon dioxide with an alkaline solution to form a carbon dioxide charged water; and b) contacting the carbon dioxide charged water with calcium sulfate under one or more precipitation conditions that favor the formation of a composition comprising a metastable component selected from the group consisting of vaterite, amorphous calcium carbonate, and combination thereof, wherein the one or more precipitation conditions include, but not limited to, temperature, pH, residence time, proton removing agent, additive, ion ratio, rate of precipitation, mixing rate, form of agitation, presence of seed crystal, catalyst, membrane, or substrate, separation, drying, refining, or combination thereof). As such, one of ordinary skill in the art would appreciate that precipitation conditions including proton removing agent and ion ratio is a result effective variable that could be optimized to provide the desired precipitated composition. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have optimized precipitation conditions including proton removing agent and ion ratio as taught by Kendall so as to arrive at a range as claimed “with a molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 > 2.00”, reacting the starting material with carbon dioxide at… ambient pressure… and at a temperature in the range from 10 to 145 oC either… in an aqueous liquid (see Kendall at [0037] teaching contact protocols for absorbing CO2, include, but not limited to: direct contacting protocols, e.g., bubbling the gas through the volume of water, concurrent contacting means… contact may be accomplished through use of infusers, bubblers… as may be convenient, see Kendall at [0059] teaching temperature of the aqueous solution… temperature to between 0o C and 100o C) (see MPEP 2144.05(I)). Direct contact protocols for absorbing CO2 is taken to meet the claimed “ambient pressure” because direct contact protocols do not require an overpressure, at a water : solids weight ratio from 1 to 100 (see Kendall at [0082] teaching in some embodiments, the ratio of the aqueous medium to the dry components… is 0.1-10) (see MPEP 2144.05(I)), and obtaining a carbonated product comprising finely precipitated calcium carbonate and alkali sulfate (see Kendall at [0006] teaching c) allowing the first composition to react with calcium sulfate to form a second composition comprising CaCO3 and Na2SO4, see Kendall at [0068] teaching the above described processes result in the production of a slurry of a carbonate containing precipitate and a mother liquor, see Kendall at [0062] teaching the nature of the precipitate may be affected by the pH of the precipitation process… in some embodiments, the high pH may lead to rapid precipitation and agglomeration of the particles whereas lower pH or slow raise in the pH may lead to finer particles). Regarding claim 2, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein the starting is reacted with carbon dioxide… at ambient pressure (see Kendall at [0037] teaching contact protocols for absorbing CO2, include, but not limited to: direct contacting protocols). Direct contact protocols for absorbing CO2 is taken to meet the claimed ambient pressure. Regarding claims 3 and 21, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein the starting material is provided by mixing a material comprising calcium sulfate, wherein the material comprising calcium sulfate is selected from the group consisting of… gypsum… to provide calcium sulfate (see Kendall at [0030] teaching in some embodiments, the methods… are integrated with the FGD process that produces gypsum), and a material comprising alkali metal ions selected from the group consisting of dusts collected during cement and clinker production… to provide alkali metal ions (claim 3), wherein the dusts collected during cement and clinker production are… clinker kiln dust (claim 21) (see Kendall [0044] teaching in addition to comprising cations… and other suitable metal forms… waste streams from various industrial processes… may provide proton-removing agents… such waste streams include, but are not limited to, mining wastes… cement kiln waste (e.g., cement kiln dust (CKD)). Regarding claims 4 and 16-17, Kendall teaches the limitations as applied to the respective claims 1-3 above, and Kendall further teaches wherein the molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 in the starting material ranges from 2.00 to 5.00 (claim 4), wherein the molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 in the starting material ranges from 2.00 to 5.00 (claim 16), and wherein the molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 in the starting material ranges from 2.00 to 5.00 (claim 17) (specification at [0013] discloses that [Symbol font/0x53] Alk is the sum of soluble alkali metal ions, and [Symbol font/0x53] SO3 is the sum of sulfate or sulfite ions, see Kendall at [0028]-[0029] teaching calcium sulfate source may include, but is not limited to… flue gas desulfurization… for example, in some embodiments, SO2 may be absorbed in a solution as sulfite, see Kendall at [0006] teaching in some embodiments, the calcium sulfate is a powder, see Kendall at [0057] teaching there are provided methods for making a composition, comprising a) contacting an industrial waste gas stream comprising carbon dioxide with an alkaline solution to form a carbon dioxide charged water; and b) contacting the carbon dioxide charged water with calcium sulfate under one or more precipitation conditions that favor the formation of a composition comprising a metastable component selected from the group consisting of vaterite, amorphous calcium carbonate, and combination thereof, wherein the one or more precipitation conditions include, but not limited to, temperature, pH, residence time, proton removing agent, additive, ion ratio, rate of precipitation, mixing rate, form of agitation, presence of seed crystal, catalyst, membrane, or substrate, separation, drying, refining, or combination thereof). As such, one of ordinary skill in the art would appreciate precipitation conditions including proton removing agent and ion ratio is a result effective variable that could be optimized to provide the desired precipitated composition. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have optimized precipitation conditions including proton removing agent and ion ratio as taught by Kendall so as to arrive at a range as claimed “wherein the molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 in the starting material ranges from 2.00 to 5.00” (claim 4), “wherein the molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 in the starting material ranges from 2.00 to 5.00” (claim 16), and “wherein the molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 in the starting material ranges from 2.00 to 5.00” (claim 17). Regarding claim 5, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein… sulfite… present in the… starting material is oxidized to sulfate prior to carbonation (see Kendall at [0029] teaching in some embodiments, SO2 may be absorbed in a solution as sulfite, which, in turn, may be converted to sulfate by oxidation through aeration). Regarding claim 6, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein a particle size of… the starting material… used to provide the starting material is optimized by… grinding (see Kendall at [0031] teaching depending upon the particle size of the sourced calcium sulfate, the calcium sulfate may be… ground). Regarding claim 7, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein exhaust gas from… coal fired power plant… is used as the carbon dioxide (see Kendall at [0031]-[0032] teaching in certain embodiments, the CO2 source is a gaseous CO2 source… this gaseous CO2 is… a waste stream or product from an industrial plant… in some embodiments, a waste stream suitable for systems and methods… is sourced from… a coal-fired power plant). Regarding claim 8, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein the reaction time ranges from 1 to 100 minutes (see Kendall at [0060] teaching the residence time of the precipitate in the reactor before the precipitate is removed from the solution, may vary… in some embodiments, the residence time of the precipitate in the solution is more than 5 seconds… without being limited by any theory, it is contemplated that the residence time of the precipitate may affect the size of the particle) (see MPEP 2144.05(I)). Regarding claims 9-10, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein carbonation is carried out in aqueous suspension by bubbling the carbon dioxide in gaseous form through the aqueous suspension (claim 9), wherein a solid product comprising calcium carbonate is separated from the aqueous suspension by precipitation (claim 10) (see Kendall at [0003] teaching a method of making a composition, comprising a) contacting an industrial waste gas stream comprising carbon dioxide with an alkaline solution to form a carbon dioxide with an alkaline solution to form a carbon dioxide charged water; and b) contacting the carbon dioxide charged water with calcium sulfate to form a composition comprising a metastable component selected from the group consisting of vaterite, amorphous calcium carbonate, and combination thereof… in the some embodiments, the method further comprises removing water, sodium sulfate, or both from the composition, see Kendall at [0037] teaching contact protocols for absorbing CO2, include, but not limited to: direct contacting protocols, e.g., bubbling the gas through the volume of water, concurrent contacting means… contact may be accomplished through use of infusers, bubblers… as may be convenient). Regarding claims 11-12 and 19, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein carbonation is carried out in a gas-solid reactor (claim 11), wherein calcium carbonate is separated from alkali sulfate by suspending the carbonated product in water and precipitating the calcium carbonate (claim 12), and wherein the gas-solid reactor is a mill and calcium carbonate is separated from alkali sulfate by suspending the carbonated product in water and precipitating the calcium carbonate (claim 19) (see claim 1 rejection, wherein the claimed “gas-solid reactor” is met by “aqueous liquid” as taught by Kendall (see MPEP 2111.04.II)). Regarding claim 13, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein the obtained carbonated product comprising calcium carbonate and alkali sulfate is used… as cement component (see Kendall at [0008]-[0009] teaching also provided is composition, comprising CaCO3 and Na2SO4, wherein the composition is self-cementing… in some embodiments, CaCO3 and Na2SO4 form a composite… also provided is a composition, comprising a concrete mixture comprising a binder and an aggregate, wherein the binder comprises a composition in accordance with foregoing compositions, see Kendall at [0087] teaching the methods… form the compositions comprising metastable components selected from the group consisting of vaterite, amorphous calcium carbonate, and combination thereof… the “cementitious composition”… includes calcium carbonate containing compositions). Regarding claims 14-15, Kendall teaches the limitations as applied to claims 1 and 13 above, and Kendall further teaches wherein the starting material contains at least 15 wt.%... sulfate… calculated as calcium sulfate to provide… the cement component being an activator (claim 14), and the starting material contains from 0.1 to 25 wt.%... sulfate… calculated as calcium sulfate (claim 15) (see Kendall at [0018] teaching calcium sulfate (gypsum), see Kendall at [0055] teaching in some embodiments, the gypsum powder or gypsum containing water is added is added to the reactor containing… less than 20%... of the CO2 gaseous stream or the solution containing the partially or fully dissolved CO2) (see MPEP 2144.05(I)). Calcium sulfate (gypsum) is expected to be capable of the claimed “the cement component being an activator” in claim 14. Regarding claim 18, Kendall teaches the limitations as applied to claim 1 above, and Kendall further teaches wherein the particle size is adjusted to range from 0.1 µm to 200 µm (see Kendall at [0006] teaching the calcium sulfate comprises particles less than about 150 microns) (see MPEP 2144.05(I)). Regarding claim 20, Kendall teaches the limitations as applied to claims 1 and 13 above, and Kendall further teaches wherein the starting material contains at least 50 wt.%... sulfate… calculated as calcium sulfate (Kendall teaches this limitation as outlined below). Kendall teaches the source of calcium sulfate… when combined with an aqueous solution of sodium carbonate… from electrochemical system… may react in accordance with the following equation to produce calcium carbonate (see Kendall at [0053]): PNG media_image1.png 39 347 media_image1.png Greyscale One of ordinary skill in the art would appreciate that 1 mole of sodium carbonate reacts with 1 mole of calcium sulfate to produce 1 mole of calcium carbonate, as outlined in the equation above. As such, one of ordinary skill in the art would appreciate that the amount of calcium sulfate is a result effective variable that could be optimized to provide the desired calcium carbonate product. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have optimized the amount of calcium sulfate as taught by Kendall to provide the desired calcium carbonate product so as to arrive at the claimed “wherein the starting material contains at least 50 wt.%... sulfate… calculated as calcium sulfate”. Regarding claim 22, Kendall teaches a method for sequestering carbon dioxide (see Kendall at [0003] teaching a method of making a composition, comprising a) contacting an industrial waste gas stream comprising carbon dioxide) comprising providing a starting material comprising calcium ions, sulfate… sulfite.. ions, and alkali metal ions (see Kendall at [0006] teaching a method, comprising: a) preparing a first composition comprising Na2CO3, NaHCO3, or a mixture thereof; b) adding calcium sulfate to the first composition, see Kendall at [0030] teaching as illustrated in FIG. 2, the SOx gas from flue gas may be subjected to flue gas desulfurization producing calcium sulfite which after hydration may form calcium sulfate). The first composition comprising Na2CO3, NaHCO3, or a mixture thereof is taken to meet the claimed alkali metal ions, and calcium sulfate/sulfite are taken to meet the claimed calcium ions, sulfate and sulfite ions, with a molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 being 2.68 to 5.00 (specification at [0013] discloses that [Symbol font/0x53] Alk is the sum of soluble alkali metal ions, and [Symbol font/0x53] SO3 is the sum of sulfate or sulfite ions, see Kendall at [0028]-[0029] teaching calcium sulfate source may include, but is not limited to… flue gas desulfurization… for example, in some embodiments, SO2 may be absorbed in a solution as sulfite, see Kendall at [0006] teaching in some embodiments, the calcium sulfate is a powder, see Kendall at [0057] teaching there are provided methods for making a composition, comprising a) contacting an industrial waste gas stream comprising carbon dioxide with an alkaline solution to form a carbon dioxide charged water; and b) contacting the carbon dioxide charged water with calcium sulfate under one or more precipitation conditions that favor the formation of a composition comprising a metastable component selected from the group consisting of vaterite, amorphous calcium carbonate, and combination thereof, wherein the one or more precipitation conditions include, but not limited to, temperature, pH, residence time, proton removing agent, additive, ion ratio, rate of precipitation, mixing rate, form of agitation, presence of seed crystal, catalyst, membrane, or substrate, separation, drying, refining, or combination thereof). As such, one of ordinary skill in the art would appreciate that precipitation conditions including proton removing agent and ion ratio is a result effective variable that could be optimized to provide the desired precipitated composition. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have optimized precipitation conditions including proton removing agent and ion ratio as taught by Kendall so as to arrive at a range as claimed “with a molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 being 2.68 to 5.00”, reacting the starting material with carbon dioxide at… ambient pressure… and at a temperature in the range from 10 to 145 oC either… in an aqueous liquid (see Kendall at [0037] teaching contact protocols for absorbing CO2, include, but not limited to: direct contacting protocols, e.g., bubbling the gas through the volume of water, concurrent contacting means… contact may be accomplished through use of infusers, bubblers… as may be convenient, see Kendall at [0059] teaching temperature of the aqueous solution… temperature to between 0o C and 100o C) (see MPEP 2144.05(I)). Direct contact protocols for absorbing CO2 is taken to meet the claimed “ambient pressure” because direct contact protocols do not require an overpressure, at a water : solids weight ratio from 1 to 100 (see Kendall at [0082] teaching in some embodiments, the ratio of the aqueous medium to the dry components… is 0.1-10) (see MPEP 2144.05(I)), and obtaining a carbonated product comprising finely precipitated calcium carbonate and alkali sulfate (see Kendall at [0006] teaching c) allowing the first composition to react with calcium sulfate to form a second composition comprising CaCO3 and Na2SO4, see Kendall at [0068] teaching the above described processes result in the production of a slurry of a carbonate containing precipitate and a mother liquor, see Kendall at [0062] teaching the nature of the precipitate may be affected by the pH of the precipitation process… in some embodiments, the high pH may lead to rapid precipitation and agglomeration of the particles whereas lower pH or slow raise in the pH may lead to finer particles). Response to Arguments Applicant’s amendments that narrows the claim limitations have obviated the previous rejection. However, upon further consideration, a new ground of rejection is set forth using the same reference Kendall. Thus, relevant arguments are addressed below. Applicant discusses that the Kendall and the present application is different… Kendall provides a method needing two steps, while the present application recites a one-step approach (see Applicant’s arguments at page 10 paragraph 4 page 11 paragraph 2). Examiner acknowledges the arguments and respectfully notes that the argument is not commensurate with what is claimed. The method as claimed in independent claims 1 and 22 are broadly recited and comprises providing a starting material, reacting the starting material with carbon dioxide, and obtaining a carbonated product. Kendall has reasonably met the claimed limitations of independent claims 1 and 22. As such, the rejection is maintained. Applicant discusses the claimed “molar ratio [Symbol font/0x53] Alk : [Symbol font/0x53] SO3 > 2.00” based on Kendall, as evidenced by Hill (see page 11 paragraph 3 to page 14 paragraph 3). Examiner have been considered the arguments but are moot because the new ground of rejection relies on the teaching that precipitation conditions including proton removing agent and ion ratio is a result effective variable (see independent claims 1 and 22). As such, the rejection is maintained. 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. Any inquiry concerning this communication or earlier communications from the examiner should be directed to MARITES A GUINO-O UZZLE whose telephone number is (571)272-1039. The examiner can normally be reached M-F 8am-4pm EST. 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, Amber R Orlando can be reached at (571)270-3149. 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. /MARITES A GUINO-O UZZLE/Examiner, Art Unit 1731
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Prosecution Timeline

Dec 14, 2023
Application Filed
Apr 29, 2026
Non-Final Rejection mailed — §103
Jul 16, 2026
Response Filed
Oct 06, 2026
Final Rejection mailed — §103 (current)

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Prosecution Projections

3-4
Expected OA Rounds
69%
Grant Probability
86%
With Interview (+16.6%)
3y 1m (~3m remaining)
Median Time to Grant
Moderate
PTA Risk
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