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 .
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.
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 29 April 2026 has been entered.
Terminal Disclaimer
The terminal disclaimer filed on 29 April 2026 disclaiming the terminal portion of any patent granted on this application which would extend beyond the expiration date of US Pat. 10,954,582 and/or any patent issued from application 17/706,584 has been reviewed and is accepted. The terminal disclaimer has been recorded.
The prior non-statutory double patenting rejections are withdrawn.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 28 April 2026 has been received and considered by the examiner.
Claim Amendments
Applicant’s amendment to claim 1 in the reply filed 29 April 2026 has been entered and considered for this action.
Response to Arguments
Applicant's arguments filed 29 April 2026 have been fully considered but they are not persuasive.
Applicant argues that that the limitation “derived from acid mine drainage and essentially free of solids” incorporated into claim 1 renders the claim non-obvious over the prior art because the prior art does not derive their composition from acid mine drainage, and that such a limitation is not merely a product-by-process limitation because the it defines a structural and compositional characteristic to the claimed product.
However, Applicant has provided no evidence nor cited any particular structural or compositional feature beyond those recited in the claim that distinguish the claimed product from the solution taught by the prior art. Applicant’s references to distinctions identified in the Laudal reference itself are directed to distinctions in the process and starting materials, and again fail to address any distinct properties of the products. The added limitation of being derived from acid mine drainage therefore does not overcome the prior determination that the composition itself is obvious in view of the prior art.
Regarding the limitation of being “essentially free of solids,” as noted below, Laudal teaches filtering after leaching (p. 126), which will render their solution essentially free of solids, thereby satisfying this claim limitation. Zhang also filters after adjusting pH, which likewise would maintain the solution free of solids (p. 191, col. 1, ¶ 2).
The amendments therefore do not overcome the prior art and the rejections are maintained.
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.
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 1, 2, and 29-44 are rejected under 35 U.S.C. 103 as being unpatentable over Laudal (“Evaluation Of Rare Earth Element Extraction From North Dakota Coal-Related Feed Stocks”, PhD Thesis, University of North Dakota, 2017) in view of Zhang and Honaker (Internat. J. Coal Geol. 195 (2018) 189-199, hereinafter “Zhang”) .
Regarding claim 1, Laudal teaches the leaching of rare earth metals from 60-gram samples of Hagel B coal into 125 mL of sulfuric acid and filtering of this solutions, which will generate a pregnant leach solution essentially free of solids (p. 125-126). Table 22 (page 139) discloses the quantities of elements that have been leached into the acid solution. These quantities have been reproduced in Table A (below). Based on the size of the coal sample (60 g), the concentration of elements in the coal (Table A, columns 1 and 2) the volume of the solution (125 mL) and the extraction efficiency of each element (Table A, column 4), the concentrations of the various elements in the leachate are calculated (Table A, column 6). These data show that the leachate solution of Laudal comprises lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium, wherein the aggregate concentration of thorium and uranium is less than 1 mg/L (0.2 mg/L), wherein cobalt is present in an amount of 17.6 mg/L, which lies just outside the instantly claimed range of from 20 mg/L to 30 mg/L, and wherein the total rare earth concentration is 14 mg/L.
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Table A. Calculated concentrations in leachate obtained by Laudal from data presented in Table 22 of Laudal.
Laudal also discloses a pregnant leach solution generated from Harman-Hansen coal with both higher cobalt concentrations and higher total rare earth concentrations (406 mg/L and 238 mg/L, respectively, as calculated from the data in Table 22 of Laudal). These results are consistent with Laudal’s observation that different coals have different elemental composition (p. 138, ¶ 2), including different levels of rare earth elements (Fig. 31, 34, 51, and 52).
Laudal therefore teaches that their method is able to generate pregnant leach solutions with a wide range of concentrations of both cobalt and total rare earth elements, including over concentration ranges that encompass those instantly claimed.
Laudal also teaches that solution with higher rare earth concentrations have greater value and incur less additional costs (REE concentration is a major factor in measuring the success and viability of the proposed system, as a higher concentration will decrease costs of downstream purification; Appendix D, Section 4.2).
Therefore, it would have been obvious to one of ordinary skill in the art to apply the leaching method of Laudal to a variety of different coals, including ones that would generate pregnant leach solutions having cobalt and total rare earth concentrations in the instantly claimed ranges. One of ordinary skill in the art would have been motivated to do so in order to extract the valuable rare earth elements at high concentrations.
It is further noted that, generally, differences in concentration will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration 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." See MPEP 2144.05 and In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). The instantly claimed concentrations of cobalt and total rare earths are therefore considered an obvious variation and/or routine optimization of the concentrations disclosed by Laudal.
Laudal does not explicitly teach a pregnant leach solution where iron is present at concentrations less than or equal to 15 mg/L. However, Laudal does teach that removal of iron from the leachate is an important goal to increase monetization value of the rare earth extracts (Chapter 6, p. 156-160), and that methods to remove iron include pH adjustment and selective precipitation from the leachate (p. 160, ¶ 1 and Fig. 82), gravity concentration pre-treatment (p. 157, ¶ 2), and an air oxidation process (p. 160, ¶ 1 and Appendix D, p. 17-18).
Therefore, it would have been obvious to one of ordinary skill in the art to apply at least one of these techniques in order to minimize the iron concentration in the PLS solution, including into the instantly claimed range of less than 15 mg/L. One of ordinary skill in the art would have been motivated to do so in order to increase the value of the leachate by removing unwanted impurities to the greatest extent possible.
It is noted that the courts have stated where the claimed ranges “overlap or lie inside the ranges disclosed by the prior art” and even when the claimed ranges and prior art ranges do not overlap but are close enough that one skilled in the art would have expected them to have similar properties, a prima facie case of obviousness exists (see 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); Titanium Metals Corp. of America v. Banner, 778 F2d 775. 227 USPQ 773 (Fed. Cir. 1985) (see MPEP 2144.05.01). Therefore, the claimed range of iron concentrations of less than 15 mg/L merely represents an obvious variant and/or routine optimization of the solutions taught by Laudal where iron concentration is reduced by various methods.
While Laudal does teach pH adjustment to precipitate iron impurities (p. 157, ¶ 2 and p. 160, ¶ 1), Laudal does not specifically teach a pregnant leach solution with a pH from 2.8 to 3.0.
However, like Laudal, Zhang also teaches that altering the pH of a leachate solution can be used to selectively precipitate different impurities from rare earth leachates (abstract). Zhang further teaches that raising the pH of a leachate to 3.0 can remove >95% of the iron from solution (p. 194, Section 3.4), and that the solution can be filtered to remove the solids precipitate by increasing the pH (p. 191, col. 1, ¶ 2). Zhang further teaches that raising the pH further may causes additional loss of rare earth ions (p. 195, ¶ 1, Table 3 and Fig. 9b).
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to increase the pH of the solutions obtained by Laudal to 3.0 and to remove the solids by filtration, thereby removing nearly all of the iron, as taught by Zhang, and maintaining a pregnant leach solution essentially free of solids. One of ordinary skill in the art would have been motivated to do so in order to decrease the iron concentration and therefore increase the monetary value of the extracts, as suggested by Laudal.
While neither Laudal nor Zhang teach deriving their compositions from acid mine drainage, the source of the material that is leached represents a product-by process by limitation. "[E]ven though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process." In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985). Because no compositional distinctions between the pregnant leach solution taught by Laudal and Zhang and one derived from acid mine drainage are apparent, the instant claim in unpatentable.
Regarding claims 2 and 29-44, the concentrations of the rare earth elements disclosed by Laudal teach all the additional limitations recited in claims 2 and 29-44 (Table A, above).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Nicholas A Piro whose telephone number is (571)272-6344. The examiner can normally be reached Mon-Fri, 8:00 am-5:00 pm.
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/NICHOLAS A. PIRO/Assistant Examiner, Art Unit 1738
/PAUL A WARTALOWICZ/Primary Examiner, Art Unit 1735
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