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
The amendments and response filed 05/19/2026 have been entered. Claim 5 has been canceled. Claims 1-4 and 6-8 remain pending.
The amendments made to claims 1, 4, and 8 overcome each and every 112 rejection made in the previous Office action, thus rendering these rejections moot. These rejections are therefore withdrawn by the Examiner.
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.
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.
Claims 1-4 and 7-8 are rejected under 35 U.S.C. 103 as being unpatentable over Kim et al. 2018 (KR 101828471 B1), in view of Sorour et al., Desalination and Water Treatment, 57 (2016) 22818–22823, Gomis et al., Fluid Phase Equilibria Volume 360, 25 December 2013, Pages 248-252, and Zafarani-Moattar et al., Journal of Chemical & Engineering Data, 42 (1997) pp.1241-1243, as cited in the previous Office action, and in further view of H.-R. Na, M.-J. Kim, Determination of optimal conditions for magnesium recovery process from seawater desalination brine using paper sludge ash, sulfuric acid, and ethanol., Desalination and Water Treatment 157 (2019) 324–331, referred to herein as Kim, Sorour, Gomis, Zafarani-Moattar, and Na, respectively.
Regarding claim 1, Kim teaches a method for recovering high-purity magnesium sulfate (0001) comprising
a pre-precipitation step of mixing an alkali precipitant and seawater (0019)
a concentration step of reacting a precipitate formed in the pre-precipitation step with sulfuric acid (0019, where the acid may be sulfuric acid, 0022)
followed by filtering to obtain a first eluate (0.1 μm membrane filter, 0061, Comparative Example 3-1)
a first precipitation step of adding ethanol to the first eluate (0019, where the organic solvent may be ethanol, 0023)
and then removing a first precipitated solid to obtain a second eluate (membrane filter, 0062, Comparative Ex 3-1)
to precipitate magnesium sulfate solid (0019)
wherein the high-purity magnesium sulfate obtained by the method has a purity of at least 95.1% (ethanol sample obtains 100% efficiency, Table 3)
Kim teaches a 1:2 (v : v) ratio of ethanol with the eluted solution (Comparative Example 3-1, 0112) and a range of 1:1 to 1:2 (0120); this reduces to 0.5:1 to 1:1 which overlaps with the claimed range of the total ethanol added, of 0.6:1 to 2:1. As set forth in MPEP 2144.05, in the case where the claimed range "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. 1990). In the instant case, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to perform a method for precipitating MgSO4 as suggested by Kim where the total ratio of the ethanol to eluate is in any workable or optimum range overlapping with 0.1:1 to 1:1 as taught by Kim including the claimed range in order to obtain a volume ratio of ethanol suitable for the precipitation of magnesium.
Kim does not teach a second precipitation step of further adding ethanol to the second eluate from which the first precipitated solid has been removed, to precipitate magnesium sulfate solid.
However, Kim teaches that calcium must be removed in order to optimize magnesium extraction efficiency (0096). Furthermore, Sorour teaches an analogous method of sequential selective precipitation of Ca2+ then Mg2+ from seawater/brine (abstract), wherein Ca is precipitated using sodium carbonate followed by Mg precipitated using sodium hydroxide (p. 22820 column 1, Figure 1). It would be obvious to one skilled in the art to modify the precipitation taught by Kim with a second precipitation step as Sorour teaches, motivated to do so in order to precipitate calcium out before obtaining magnesium, as Kim teaches (0096). While Sorour teaches two precipitants of different identities to precipitate Ca and Mg, it would be obvious to one skilled in the art to use ethanol as the precipitant in both steps in order to obtain MgSO4, because Gomis teaches that CaSO4 is significantly less soluble in EtOH (wCaSO4 = 7.1 x 10-4, Table 1 at 25 degrees C) than MgSO4, taught by Zafarani-Moattar (x1exp ≈ 0.2 for 10% ethanol at 25 degrees C, Figure 1). The weight fraction, wCaSO4 , is equal to a mole fraction x of 7.9 x 10-4 as demonstrated below.
0.00071
w
=
0.071
%
w
w
C
a
S
O
4
,
and
0.09996
w
E
t
O
H
≈
10
%
w
w
E
t
O
H
;
therefore the amount of water is
89.929
%
w
w
H
2
O
0.071
172
g
m
o
l
C
a
S
O
4
∙
2
H
2
O
≈
4.13
*
10
-
3
m
o
l
C
a
S
O
4
Similar calculations yield
0.217
m
o
l
E
t
O
H
,
4.99
m
o
l
H
2
O
0.00413
4.99
+
0.217
+
0.00413
=
0.0007925
≈
7.9
*
10
-
4
=
x
It would therefore be obvious to one of ordinary skill in the art before the effective filing date of the invention to modify the invention taught by Kim with a second precipitation step as taught by Sorour, wherein the precipitant is ethanol, in order to precipitate CaSO4 and remove it before proceeding with the precipitation of MgSO4 with ethanol. One of ordinary skill in the art would be motivated to do so in order to remove CaSO4 (s) as an impurity in order to increase the amount and purity of MgSO4 (s) obtained, as Kim teaches (0096). The solubilities of CaSO4 and MgSO4 in solvents including ethanol, as properties of the chemical compounds, are inherent to the identities of the compounds as a function of temperature, and would have been evident before the effective filing date of the present invention; see MPEP 2112 (II). Therefore one of ordinary skill in the art would have motivation to modify the method taught by Kim to use the ethanol twice to obtain eluates and precipitated solids, instead of once as Kim teaches in the sole ethanol step (0019), and one of ordinary skill in the art would have reasonable expectation of obtaining results of solubility taught by Gomis (Figure 1, Table 1) and Zafarani-Moattar (Figure 1, Table 1).
Kim additionally does not teach, in a first precipitation step, a 0.2:1 to 0.4:1 ratio of ethanol to eluate. However, Na discloses a method for precipitating MgSO4 from seawater (p. 325 col. 2 pp. 1) wherein ethanol is added to eluate to precipitate MgSO4 (p. 325 col. 2, ‘Materials and methods’ paragraph 2; the filtrate is called “eluent” which corresponds to the “eluate” of the instant invention, p. 326 ‘Precipitation of MgSO4’). Na discloses that an “amount of Ca decreased when a small amount of ethanol (volume ratio of 1:0.4 or less) was injected into the eluent” (p. 329 col. 1); this range overlapping with the instant claimed range. It would be obvious to one skilled in the art to combine the teachings of Kim, Sorour, Gomis, and Zafarani-Moattar with the teachings of Na to arrive at the calcium precipitation step using a volume ratio of 0.4 or less :1 of ethanol to eluate, as Na teaches; one would be motivated to do so in order to precipitate calcium, since it hinders the purity of the precipitation of MgSO4, as Kim teaches (0096), and since Na teaches that adding ethanol in a higher ratio could result in the MgSO4 containing Ca as an impurity (p. 329 col. 1). Therefore one skilled in the art would arrive at the claimed invention prior to the effective filing date. Regarding the overlap of this range with the instant claimed range of 0.2:1 to 0.4:1, as set forth in MPEP 2144.05, in the case where the claimed range "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. 1990). In the instant case, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to perform a method for precipitating MgSO4 as suggested by Kim, Sorour, Gomis, Zafarani-Moattar, and Na where the ratio of the ethanol to eluate in the first precipitation step is in any workable or optimum range overlapping with 0.4 or less :1 as taught by Na including the claimed range in order to obtain a volume ratio of ethanol suitable for the precipitation of calcium.
Regarding claim 2, Kim teaches NaOH, paper sludge ash (PSA), cement kiln dust (CKD), slag, and fly ash, 0006, fuel ash, bottom ash, fly ash, de-inking ash, steelmaking slag, and waste concrete, 0021. This meets the instant limitation of the alkali precipitant being any one selected from alkaline industrial byproducts consisting of sodium hydroxide, calcium hydroxide, paper sludge ash (PSA), cement kiln dust (CKD), fuel ash, bottom ash, fly ash, de-inking ash, slag, waste concrete, and mixtures thereof.
Regarding claim 3, Kim teaches seawater, title. Without evidence that “ordinary seawater” required in the instant claim is different in identity than seawater, this is interpreted to meet the limitation of ordinary seawater required in the instant claim.
Regarding claim 4, Kim teaches that the concentrations of magnesium and calcium in the seawater being 1300 and 443 mg/L, respectively, 0072, and the concentration of magnesium in the eluate was 4850 to 5300 mg/L (0111, 0112); this is about 4 times the Mg concentration in the seawater used in the pre-precipitation step, falling within the claimed range of 3 to 5 times the Mg concentration in the seawater.
Kim does not teach the concentration of Ca after precipitating CaSO4. However, Na teaches an analogous process of precipitating CaSO4 with 1.0 M H2SO4 wherein the seawater used contains 664 mg/L of Ca (Table 1) and the eluate contains 725 mg/L of Ca (Table 3), which gives a value of about 1.1 times the Ca concentration in the seawater, falling within the claimed range of 0.5 to 1.5 times the Ca concentration in the seawater. It would be obvious to one skilled in the art to combine the teachings of Kim and Na and obtain the concentration of Ca in the first eluate being 1.1 times the concentration of Ca in the seawater, since Na teaches that the conditions which lead to the Ca concentration of 725 (the 1 M H2SO4) are sufficient to produce MgSO4 of high purity (p. 329 col. 2, 89.6% purity and up to 93%, whereas the stronger 1.5 M H2SO4 contains too many impurities, Al, Fe). Therefore one skilled in the art would be motivated to obtain a first eluate wherein the Ca is present in the concentration disclosed by Na in the intermediate precipitation step. Thus one skilled in the art would arrive at the claimed invention.
Regarding claim 7, Kim teaches performing fractional distillation on the organic solvent to recover the organic solvent (0067, 0069, 0122, 0126). Kim does not teach the use of fractional distillation on ethanol, specifically. However, it would be obvious to one skilled in the art before the effective filing date of the invention to modify the invention taught by Kim by replacing the acetone taught by Kim with the ethanol taught by Kim. One would be motivated to do so because Kim teaches that the organic solvent that is recovered can be the ethanol (pyridine, acetone, ethanol, 0120). One of ordinary skill in the art would therefore arrive at the claimed invention with reasonable prediction of success.
Regarding claim 8, Kim teaches the purity of magnesium sulfate obtained is 95 to 100%, 0024. As set forth in MPEP 2144.05, in the case where the claimed range "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. 1990). It would have been obvious to one of ordinary skill in the art at the time of filing of the invention to perform the method as suggested by Kim, Gomis and Zafarani-Moattar where the purity of the MgSO4 product is in any workable or optimum range overlapping with 95 to 100%, as taught by Kim, including the claimed range of at least 99.8%, in order to obtain a product of suitable purity.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Kim in view of Sorour, Gomis, Zafarani-Moattar, and Na, as applied to claim 1 above, and in further view of Roche et al. US 20090148365 A1, herein referred to as Roche.
Regarding claim 6, Kim, Sorour, Gomis, Zafarani-Moattar, and Na discloses a method of obtaining solid MgSO4 as applied to claim 1 above.
They do not disclose a step of separating the precipitated magnesium sulfate solid after the second precipitation step followed by drying at room temperature.
However, Roche teaches a process for recovering solid magnesium sulfate hydrate (abstract) wherein the crystals are separated from the acid by filtration (0051) and washed with ethanol and then allowed to stand at ambient temperature to evaporate excess ethanol (0052). It would therefore be obvious to one skilled in the art to modify the invention suggested by Kim, Sorour, Gomis, Zafarani-Moattar, and Na to further include the step of separating the precipitated magnesium sulfate solid after the second precipitation step followed by drying at room temperature. One would be motivated to do so in order to obtain the solid and evaporate excess ethanol, as Roche teaches (0052).
Response to Arguments
Applicant's arguments filed 5/19/2026 have been fully considered but they are not persuasive.
Applicant asserts that there is no disclosure in the prior art to suggest a reason why a person of ordinary skill in the art would have added ethanol and filtered sequentially in the method disclosed in Kim in a manner that would correspond to the presently claimed invention. In response to applicant’s argument that there is no teaching, suggestion, or motivation to combine the references, the examiner recognizes that obviousness may be established by combining or modifying the teachings of the prior art to produce the claimed invention where there is some teaching, suggestion, or motivation to do so found either in the references themselves or in the knowledge generally available to one of ordinary skill in the art. See In re Fine, 837 F.2d 1071, 5 USPQ2d 1596 (Fed. Cir. 1988), In re Jones, 958 F.2d 347, 21 USPQ2d 1941 (Fed. Cir. 1992), and KSR International Co. v. Teleflex, Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007). In this case, Kim teaches that calcium sulfate must be precipitated in order to prevent calcium from interfering with the recovery of magnesium (0096), and it is well known in the art that calcium sulfate is much less soluble than magnesium sulfate as demonstrated by Gomis and Zafarani-Moattar. The prior art therefore motivates the combination of the teachings to arrive at the claimed invention. The Applicant asserts that the combined teachings of the prior art would, at best, indicate that both calcium sulfate and magnesium sulfate would precipitate out, but this is the goal of the present invention as well. That the present invention separates these two precipitants in two precipitation steps is taught by the combination of Sorour, in precipitating out Ca ions before proceeding with Mg ions (page 3), and the use of ethanol taught by Kim (0023), and thus the combination of teachings arrives at the claimed invention with ethanol used as the precipitant in both steps. Regarding applicant’s assertion that the teachings of Gomis and Kim would suggest that both CaSO4 and MgSO4 would precipitate out, rather than the selective precipitation of CaSO4, the Examiner finds this unconvincing in light of the solubility mole fractions taught by Zafarani-Moattar and Gomis, as discussed in the previous Office action. The combination of the prior art renders obvious to one skilled in the art that CaSO4 is much less soluble in ethanol than MgSO4 and therefore one would see a precipitation of CaSO4 until the quantity of ethanol added is sufficient to precipitate MgSO4.
Applicant asserts that the ranges of the volume ratios of ethanol to the first eluate and second eluate are not taught in the prior art; this argument is rendered moot by the new grounds of rejection set forth above.
Applicant asserts that there is no motivation to increase ethanol concentration between the first and second precipitation steps. The Examiner notes that the difference in solubility between CaSO4 and MgSO4 in ethanol, as taught by Gomis and Zafarani-Moattar, provides such motivation. It would be obvious to one skilled in the art that a higher concentration of ethanol would result in more MgSO4 precipitated after having precipitated CaSO4.
Applicant asserts that the same solvent being used to remove calcium sulfate in one step and then later remove magnesium sulfate in another is not disclosed in a single document. However, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). In the instant case, Kim and Sorour disclose sequentially removing calcium then magnesium, Kim discloses calcium sulfate and magnesium sulfate, and Gomis and Zafarani-Moattar motivate the use of ethanol as the precipitant; thus the combination of teachings arrives at the claimed invention.
Regarding claim 6, Applicant asserts that Roche does not overcome the deficiencies of Kim, Gomis, and Zafarani-Moattar. This argument is rendered moot by the new grounds of rejection set forth above.
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 Eileen Moudou whose telephone number is (571)272-1768. The examiner can normally be reached M-Th 8 AM - 4 PM 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, Sally Merkling can be reached at (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.
/Eileen Moudou/ Examiner, Art Unit 1738
/MICHAEL FORREST/ Primary Examiner, Art Unit 1738
Prosecution Insights