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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 15 June 2026 has been entered.
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.
Claims 1, 2, 7, 8, 10-12, 14-16, 19, 20, and 24-27 are rejected under 35 U.S.C. 103 as being unpatentable over Dougherty et al (WO 2016/081030) in view of Kelsall et al (GB 2368349 A), Applicant’s admission of prior art, and Darron et al (US 2010/0089763 A1, equivalent to WO 2008/039478 A2 cited by Applicant).
Dougherty et al teach (see abstract, fig. 1B, paragraphs [0013], [0035] and [0036]) treatment of an electrolyte comprising methane sulfonic acid that comprised a first metal ion (e.g. silver) and a second metal ion (e.g. lead), wherein the first metal (silver) is more noble than the second metal and wherein the first metal ion is present in the electrolyte at a lower concentration than the second metal ion, and wherein the second metal ion is a lead ion. The treatment included (see paragraph [0036]) a pre-treatment for selective removal of the first metal ion, such as by using selective electrodeposition to remove the first metal ion while leaving the second metal ion in the electrolyte.
Dougherty et al is silent with respect to the exact concentrations of the first metal ion and the second metal ion. However, Dougherty et al teach that lead is the primary metal recovered from lead batteries and that the silver was present in the lead battery in a minor amount and extracted into the electrolyte along with the lead, and thus present at a lower amount than the lead. Further, Applicant characterized, in paragraph [0006] of the instant specification, that the lead electrolyte of the prior art, including the electrolyte produced by Dougherty et al, typically included 20-200 g/l of lead, about 5 mg/l of silver and about 5mg/l of copper.
Dougherty et al do not teach that the selective electrodeposition step comprises feeding the electrolyte into a reactor having an anode and a high-surface area cathode and controlling the electrode potential at the cathode to reduce the first metal ion in the presence of the second metal to produce a pre-treated electrolyte that comprised the second metal ion while being substantially depleted of the first metal ion.
Kelsall et al teach (see abstract, figs. 1, 3, and 5, page 1, lines 6-22 and “Potential Control” section on pages 2-3) a method for the selective recovery of a metal ion from a solution that contains multiple metal ions, wherein the potential of the cathode, such as a graphite felt cathode, is controlled to deposit the more noble metal onto the cathode while not depositing the less noble metal. Kelsall et al teach that as long as the deposition potential difference between the two metals was greater than 0.18 V, the completely separate recovery of the metals was expected. Per fig. 1, the potential difference between silver and lead, from a chloride solution, was 0.652 V, thus indicating that the silver and lead of Dougherty et al could easily be separated by depositing the silver onto the graphite felt cathode using a controlled cathode potential. In the process of Kelsall et al, the more noble metal ion is preferentially deposited onto the high-surface area cathode.
Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to have utilized the graphite felt cathode (i.e. a “high-surface area cathode” as claimed) and a step of controlling the electrode potential of the cathode as taught by Kelsall et al in a reactor having an anode and the cathode in order to perform the selective electrodeposition of silver from the solution of Dougherty et al because Kelsall et al teach that the graphite felt cathode in combination with controlling the potential of the graphite felt cathode permitted selective recovery of silver ions as silver metal from a solution that also contained lead ions.
It is further clear from the teachings of Kelsall et al (see fig. 5, page 2, lines 18-25) that the degree of recovery of the metal ions from the solution increased with respect to time, where the degree of removal of the metal ions increased over time. Therefore, absent a showing of unexpected results, it would have been obvious to one of ordinary skill in the art at the time of filing to have conducted the step of Kelsall et al to achieve a desired level of impurity (silver and/or copper) removal from the lead electrolyte of Dougherty et al to increase the purity of the recovered lead. See also MPEP 2144.04.VII. A difference in level of purity is not per se nonobvious as long as the prior art suggested a technique capable of achieving the claimed purity. The process of Kelsall et al, based upon the evidence of record, would have been capable of achieving the claimed purity of the solution with respect to silver and copper content, such as equal to or less than 5 ppb.
Kelsall et al fail to describe the surface area to weight ratio of the graphite felt. However, the graphite felt was present to “maximize the recovery of metals present at low concentrations” (pg. 1, lines 19-22). Absent a showing of unexpected results, it would have been within the ordinary level of skill in the art to have performed routine experimentation to determine a suitable range of surface area to weight ratio for the graphite felt to achieve the increased recovery of the metals present at low concentrations. Applicant has not demonstrated that the claimed range of surface area to weight produces a result different from the prior art.
Dougherty et al and Kelsall et al fail to teach arranging the graphite felt cathode as a flow-through electrode.
Darron et al teach (see fig. 2, abstract, paragraphs [0007], [0012], and [0059]) that electrochemical cells for recovery of metals from electrolyte solutions can be arranged with cathodes as “flow-through” cathodes, such as carbon felt electrodes, and the flow-through carbon felt cathodes were capable of recovering metal ions present at even low concentrations. The flow-through cathodes possessed high surface area for effectively permitting deposition of the metal from the circulating electrolyte.
Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to have adapted the graphite cathode of Kelsall et al as a flow-through cathode as suggested by Darron et al to provide recovery of even low concentrations of the silver ions from the electrolyte of Dougherty et al.
The claim limitation “wherein the electrochemical polishing reactor and the high-surface area flow-through cathode are configured to be operable at a flow rate that allows continuous lead recovery at a downstream cathode in a downstream lead reduction reactor” is noted. The broadest reasonable interpretation of this claim limitation in light of the originally filed specification merely requires the electrochemical polishing reactor to be operable with a flow rate of at least 50 mL/min (see paragraphs [0024] and [0027] of the instant specification). Darron et al teach (see paragraph [0061]) operating the high-surface area flow through cathode at a flow rate of 20 mL/sec (1200 mL/min). Therefore, the electrochemical polishing apparatus of Kelsall et al as modified by Darron et al meets this claim limitation.
The claim limitation “wherein a current density at the high-surface area flow-through cathode is less than 5 mA/cm2” is noted. Kelsall et al include several disclosures relating to the applied current density. In fig. 4, the current density is taught as being no more than 200 A/m2 (20 mA/cm2). In fig. 10, Kelsall et al showed using current densities of 161.6, 202.0, and 242.4 A/m2 (16.16, 20.20, and 24.24 mA/cm2,respectively). Figs. 11-13 all disclose operating at 484.8 A/m2 (48.48 mA/cm2). Each of these values are above the claimed range of less than 5 mA/cm2. However, Kelsall et al go on to teach (see page 3, lines 14-33 and fig. 14) that current efficiency of the metal removal increased with decreasing current density. Thus, the totality of the teachings of Kelsall et al would have suggested to one of ordinary skill in the art at the time of filing to operate with a very low current density, e.g. below 50 A/cm2 (5 mA/cm2), when current efficiency was the most important variable for optimization in the process.
Regarding claims 2 and 7, Kelsall et al and Darron et al teach using a carbon or graphite felt material for the flow through cathode.
Regarding claim 8, Dougherty et al teach the first metal ion being silver ions.
Regarding claim 10, Dougherty et al teach (see paragraph [0058], Table 3) recovering the lead from the pre-treated electrolyte in an electrochemical reactor.
Regarding claim 11, Dougherty et al teach (see abstract, fig. 1B, paragraphs [0013], [0035] and [0036]) treatment of a lead-enriched electrolyte comprising methane sulfonic acid that comprised a first metal ion (e.g. silver) and a second metal ion (e.g. lead), wherein the first metal (silver) is more noble than the second metal and wherein the first metal ion is present in the electrolyte at a lower concentration than the second metal ion, and wherein the second metal ion is a lead ion. The treatment included (see paragraph [0037]) a pre-treatment for selective removal of the first metal ion, such as by using selective electrodeposition to remove the first metal ion while leaving the second metal ion in the electrolyte.
Dougherty et al is silent with respect to the exact concentrations of the first metal ion and the second metal ion. However, Dougherty et al teach that lead is the primary metal recovered from lead batteries and that the silver was present in the lead battery in a minor amount and extracted into the electrolyte along with the lead, and thus present at a lower amount than the lead. Further, Applicant characterized, in paragraph [0006] of the instant specification, that the lead electrolyte of the prior art, including the electrolyte produced by Dougherty et al, typically included 20-200 g/l of lead and about 5 mg/l of silver.
Dougherty et al do not teach that the selective electrodeposition step comprises feeding the electrolyte into an electrochemical reactor having an anode and a high-surface area flow-through cathode and applying a low current of controlling electrode potential to the cathode to reduce the first metal ion in the presence of the lead ions to produce a pre-treated electrolyte that comprised the lead ions while being substantially depleted of the first metal.
Kelsall et al teach (see abstract, figs. 1, 3, and 5, page 1, lines 6-22 and “Potential Control” section on pages 2-3) a method for the selective recovery of a metal ion from a solution that contains multiple metal ions, wherein the potential of the cathode, such as a graphite felt cathode, is controlled to deposit the more noble metal onto the cathode while not depositing the less noble metal. Kelsall et al teach that as long as the deposition potential difference between the two metals was greater than 0.18 V, the completely separate recovery of the metals was expected. Per fig. 1, the potential difference between silver and lead, from a chloride solution, was 0.652 V, thus indicating that the silver and lead of Dougherty et al could easily be separated by depositing the silver onto the graphite felt cathode using a controlled cathode potential.
Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to have utilized the graphite felt cathode (i.e. a “high-surface area cathode” as claimed) and a step of controlling the electrode potential of the cathode as taught by Kelsall et al in a reactor having an anode and the cathode in order to perform the selective electrodeposition of silver from the solution of Dougherty et al because Kelsall et al teach that the graphite felt cathode in combination with controlling the potential of the graphite felt cathode permitted selective recovery of silver ions as silver metal from a solution that also contained lead ions.
It is further clear from the teachings of Kelsall et al (see fig. 5, page 2, lines 18-25) that the degree of recovery of the metal ions from the solution increased with respect to time, where the degree of removal of the metal ions increased over time. Therefore, absent a showing of unexpected results, it would have been obvious to one of ordinary skill in the art at the time of filing to have conducted the step of Kelsall et al to achieve a desired level of impurity (silver and/or copper) removal from the lead electrolyte of Dougherty et al to increase the purity of the recovered lead. See also MPEP 2144.04.VII. A difference in level of purity is not per se nonobvious as long as the prior art suggested a technique capable of achieving the claimed purity. The process of Kelsall et al, based upon the evidence of record, would have been capable of achieving the claimed purity of the solution with respect to silver and copper content, such as equal to or less than 10 ppb total.
Kelsall et al fail to describe the surface area to weight ratio of the graphite felt. However, the graphite felt was present to “maximize the recovery of metals present at low concentrations” (pg. 1, lines 19-22). Absent a showing of unexpected results, it would have been within the ordinary level of skill in the art to have performed routine experimentation to determine a suitable range of surface area to weight ratio for the graphite felt to achieve the increased recovery of the metals present at low concentrations. Applicant has not demonstrated that the claimed range of surface area to weight produces a result different from the prior art.
Dougherty et al and Kelsall et al fail to teach the cathode being configured as a flow-through cathode.
Darron et al teach (see fig. 2, abstract, paragraphs [0007], [0012], and [0059]) that electrochemical cells for recovery of metals from electrolyte solutions can be arranged with cathodes as “flow-through” cathodes, such as carbon felt electrodes, and the flow-through carbon felt cathodes were capable of recovering metal ions present at even low concentrations. The flow-through cathodes possessed high surface area for effectively permitting deposition of the metal from the circulating electrolyte.
Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to have adapted the graphite cathode of Kelsall et al as a flow-through cathode as suggested by Darron et al to provide recovery of even low concentrations of the silver ions from the electrolyte of Dougherty et al.
The claim limitation “wherein the electrochemical polishing reactor and the high-surface area flow-through cathode are configured to be operable at a flow rate that allows continuous lead recovery at a downstream cathode in a downstream lead reduction reactor” is noted. The broadest reasonable interpretation of this claim limitation in light of the originally filed specification merely requires the electrochemical polishing reactor to be operable with a flow rate of at least 50 mL/min (see paragraphs [0024] and [0027] of the instant specification). Darron et al teach (see paragraph [0061]) operating the high-surface area flow through cathode at a flow rate of 20 mL/sec (1200 mL/min). Therefore, the electrochemical polishing apparatus of Kelsall et al as modified by Darron et al meets this claim limitation.
The claim limitation “wherein the low current density at the high-surface area flow-through cathode is qual or less than 5 mA/cm2” is noted. Kelsall et al include several disclosures relating to the applied current density. In fig. 4, the current density is taught as being no more than 200 A/m2 (20 mA/cm2). In fig. 10, Kelsall et al showed using current densities of 161.6, 202.0, and 242.4 A/m2 (16.16, 20.20, and 24.24 mA/cm2,respectively). Figs. 11-13 all disclose operating at 484.8 A/m2 (48.48 mA/cm2). Each of these values are above the claimed range of less than 5 mA/cm2. However, Kelsall et al go on to teach (see page 3, lines 14-33 and fig. 14) that current efficiency of the metal removal increased with decreasing current density. Thus, the totality of the teachings of Kelsall et al would have suggested to one of ordinary skill in the art at the time of filing to operate with a very low current density, e.g. below 50 A/cm2 (5 mA/cm2), when current efficiency was the most important variable for optimization in the process.
Regarding claim 12, Dougherty et al teach (see paragraph [0058], Table 3) recovering the lead from the pre-treated electrolyte in an electrochemical reactor.
Regarding claims 14 and 15, as noted above, Dougherty et al is silent with respect to the exact concentrations of the first metal ion and the second metal ion. However, Dougherty et al teach that lead is the primary metal recovered from lead batteries and that the silver was present in the lead battery in a minor amount and extracted into the electrolyte along with the lead, and thus present at a lower amount than the lead. Further, Applicant characterized, in paragraph [0006] of the instant specification, that the lead electrolyte of the prior art typically included 20-200 g/l of lead and about 5 mg/l of silver.
Regarding claim 16, both Kelsall et al and Darron et al teach using graphite felt.
Regarding claim 19, the other metal ion of Dougherty et al included silver. Applicant characterized, in paragraph [0006] of the instant specification, that the lead electrolyte of the prior art typically included 20-200 g/l of lead, about 5 mg/l of silver, and about 8 mg/l of copper.
Regarding claim 20, Kelsall et al teach (see fig. 4) that the applied current density for the controlled potential embodiment was less than 200 A / m2 (20 mA / cm2)1. Further, Kelsall et al teach (see fig. 14, page 3, lines 14-33) that current efficiency increased as current density approached zero, with values under 100 A/m2 (10 mA/cm2) having the highest current efficiency. Therefore, as discussed with respect to claim 11 above, it would have been obvious to one of ordinary skill in the art at the time of filing to have applied a lower current density within the broad range taught by Kelsall et al to maximize the current efficiency of the impurity removal process.
Regarding claims 24 and 25, based upon the teachings of Kelsall et al, one of ordinary skill in the art at the time of filing would have been motivated to conduct the selective electrodeposition of the silver and copper under conditions such that all or substantially all of the silver and copper was removed from the electrolyte in order to fully recover the valuable silver and copper metals from the lead, while also increasing the purity of the recovered lead.
Regarding claim 26, since the electrochemical reactor suggested by Kelsall et al and Darron et al was configured with a flow-through cathode it was understood as operable on a continuous basis. Dougherty et al teach that the electrochemical reactor for production of metallic lead was operated on a continuous basis. Thus, one of ordinary skill in the art at the time of filing would have expected that the two electrochemical reactors were operated concurrently.
Regarding claim 27, Dougherty et al teach (see paragraph [0019]) that the lead could be recovered at high purity. Further, by removing impurities, such as silver, copper, etc. as suggested by Dougherty et al according to the process taught by Kelsall et al, one of ordinary skill in the art at the time of filing would have expected to increase the purity of the lead recovered in the electrochemical reactor of Dougherty et al.
Claim 18 is rejected under 35 U.S.C. 103 as being unpatentable over Dougherty et al (WO 2016/081030) in view of Applicant’s admission of prior art, Kelsall et al (GB 2368349 A) and Darron et al (US 2010/0089763 A1) as applied to claim 11 above, and further in view of Cardarelli et al (US 2010/0044243 A1).
Regarding claim 18, Kelsall et al fail to describe the composition of the anode used in the electrochemical reactor for recovery of silver. Note that the anode of Kelsall et al was taught as producing chlorine gas.
Cardarelli et al teach (see abstract, fig. 4, paragraph [0108]) in an electrochemical reactor for recovery of metal where chlorine gas was evolved at the anode, wherein the anode composition included titanium provided with a coating that comprised platinum group metals such as RuO2 or IrO2.
Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to have utilized an anode as taught by Cardarelli et al that included titanium coated with RuO2 or IrO-2 for the anode of Kelsall et al according to known techniques with a reasonable expectation of successfully forming the chlorine gas at the anode.
Response to Arguments
Applicant's arguments filed 18 February 2026 have been fully considered but they are not persuasive. Applicant has argued that:
Kelsall et al teach conducting the electrolytic impurity removal at 484 A/m2 -(48.4 mA/cm2) which is nearly an order of magnitude higher than the instantly claimed range.
In response, Applicant has chosen to focus on only one value of current density taught by Kelsall et al. A full reading of Kelsall et al shows other expressly recited examples that have lower values of current density (although still not within the claimed range). However, Kelsall et al also show (see fig. 14) that the current efficiency of the metal recovery process increased as the current density decreased. Therefore, the totality of the teachings of Kelsall et al provided motivation to one of ordinary skill in the art at the time of filing to utilize very low current densities in the process in order to achieve maximum current efficiency.
Darron et al teach conducting the electrodeposition at 3000 A/m--2.
In response, the cited current density in Darron et al (paragraph [0063]) refers to a copper plating step which utilized the flow-through graphite felt cathode. However, there is no indication that the current density was necessary to achieving the advantage of using the flow-through graphite felt as a cathode. The teachings of Darron et al are considered to be insufficient to overcome the teachings of Kelsall et al.
The Office improperly ignores the claim limitation that the high-surface area flow-through cathode and the electrochemical polishing reactor are “configured to be operable at a flow rate that allows continuous lead recovery at a downstream cathode in a downstream lead reduction reactor”.
In response, this claim limitation, by failing to recite numerical values, is limited solely by the capability of the recovery of any amount of continuous lead recovery at the downstream lead reduction reactor. Clearly the electrochemical polishing reactor as suggested by Kelsall et al and the high-surface area flow-through cathode of Darron et al were capable of supporting at least a small amount of continuous lead recovery at the downstream lead reduction reactor of Dougherty et al.
Conclusion
All claims are identical to or patentably indistinct from, or have unity of invention with claims in the application prior to the entry of the submission under 37 CFR 1.114 (that is, restriction (including a lack of unity of invention) would not be proper) and all claims could have been finally rejected on the grounds and art of record in the next Office action if they had been entered in the application prior to entry under 37 CFR 1.114. Accordingly, THIS ACTION IS MADE FINAL even though it is a first action after the filing of a request for continued examination and the submission under 37 CFR 1.114. See MPEP § 706.07(b). 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.
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/HARRY D WILKINS III/Primary Examiner, Art Unit 1794
1 The Office incorrectly converted this value in the Office action mailed 2 April 2026. The value cited here corrects the deficiency of the prior action.
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