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 .
Priority
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Information Disclosure Statement
The information disclosure statement(s) (IDS) submitted on 1/11/24 and 1/16/26 have been considered by the examiner.
Election/Restrictions
Claims 6, 9, 21-22, 31, and 51-53 withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention or species, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 9/9/26.
Specification
The lengthy specification has not been checked to the extent necessary to determine the presence of all possible minor errors. Applicant’s cooperation is requested in correcting any errors of which applicant may become aware in the specification.
Claim Objections
The Amendment filed 10/11/23 is not in compliance with 37 C.F.R. 1.121. See MPEP § 714 II C (B) Markings to Show the Changes: All claims being currently amended must be presented with markings to indicate the changes that have been made relative to the immediate prior version. The changes in any amended claim must be shown by strike-through (for deleted matter) or underlining (for added matter) with 2 exceptions: (1) for deletion of five or fewer consecutive characters, double brackets may be used (e.g., [[eroor]]); (2) if strike-through cannot be easily perceived (e.g., deletion of number "4" or certain punctuation marks), double brackets must be used (e.g., [[4]]). As an alternative to using double brackets, however, extra portions of text may be included before and after text being deleted, all in strike-through, followed by including and underlining the extra text with the desired change (e.g., number 4 as number 14 as ). An accompanying clean version is not required and should not be presented. Only claims of the status "currently amended" or "withdrawn" will include markings.
Claim 1 is marked “Previously presented” even though amendments have been made. “A method for extracting precious metal” was changed to “A method for recovering precious metal.”
Claim 6 is marked “Previously presented” even though amendments have been made. “A method for extracting precious metal” was changed to “A method for recovering precious metal.”
Claim 23 was changed from “A method as defined in 22 that is conducted subsequent to the method of any one of claims 1 to 21” to “further comprising recovering copper during the step of adding the first reductant to the leached solution” without correct markings. Claim 22 is entirely silent as to recovering copper.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112(d):
(d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
Claims 1, 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected under 35 U.S.C. 112(a) as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Regarding claim 1, the claim was amended on 1/16/26 to recite “wherein a thiosulphate generating pH is maintained at or above pH 7.5 by addition of the base”. The instant specification does not describe “wherein a thiosulphate generating pH is maintained at or above pH 7.5 by addition of the base” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The instant specification teaches that “the thiosulphate leaching process is carried out at a pH in the range of about 7.5 to about 11, including any value therebetween, e.g. 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8 or 10.9” (paragraph [0107]). The thiosulphate leaching process is step (ii) of claim 1, not step (i). The instant specification is entirely silent as to a minimum pH during the step of thiosulphate generating. Claims 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected due to their dependence on rejected claim 1.
Regarding claim 1, the claim was amended on 1/16/26 to recite “a thiosulfate generating temperature is maintained at less than 100 °C”. The instant specification does not describe “a thiosulfate generating temperature is maintained at less than 100 °C” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The instant specification teaches that “the leaching process is conducted at a temperature in the range of about 25° C. to about 95° C., including any temperature therebetween, e.g. 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85 or 90° C” (paragraph [0106]). The thiosulphate leaching process is step (ii) of claim 1, not step (i). The instant specification is entirely silent as to a maximum temperature during the step of thiosulphate generating. Claims 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected due to their dependence on rejected claim 1.
Regarding claim 1, the claim was amended on 1/16/26 to recite “a thiosulfate generating oxidation-reduction potential (ORP) is maintained by addition of the oxidant at equal to or greater than -80 mV vs. Ag/AgCI”. The instant specification does not describe “a thiosulfate generating oxidation-reduction potential (ORP) is maintained by addition of the oxidant at equal to or greater than -80 mV vs. Ag/AgCI” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. Similarly, the instant specification discusses the oxidation-reduction potential (ORP) in relation to the leaching phase, step (ii) of claim 1, rather than the thiosulphate generating phase prior to any leaching, step (i) of claim 1. The instant specification teaches that “the reaction mixture is maintained at a desired oxidation-reduction-potential (ORP), and that in some embodiments, the reaction mixture is maintained at an ORP of at least about −80 to about 100 mV (as measured using an Ag—AgCl reference electrode), including any value therebetween” (paragraph [0113). Claims 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected due to their dependence on rejected claim 1.
Regarding claim 1, the claim was amended on 1/16/26 to recite “segregating the liquid leaching solution from a solid leach residue in a first solid/liquid separation to produce a pregnant leaching solution”. The instant specification does not describe “segregating the liquid leaching solution from a solid leach residue in a first solid/liquid separation to produce a pregnant leaching solution” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The instant specification is entirely silent as to “segregating”. The instant specification is entirely silent as to a “liquid leaching solution”. The instant specification is entirely silent as to a “solid leach residue”. The instant specification is entirely silent as to “a pregnant leaching solution”. The instant specification is entirely silent as to “segregating”. Claims 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected due to their dependence on rejected claim 1.
Regarding claim 1, the claim was amended on 1/16/26 to recite “to produce a barren leach solution”. The instant specification does not describe “to produce a barren leach solution” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The instant specification is entirely silent as to “a barren leach solution”. Claims 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected due to their dependence on rejected claim 1.
Regarding claim 1, the claim was amended on 1/16/26 to recite “segregating the solid product from the barren leach solution in a second solid/liquid separation”. The instant specification does not describe “segregating the solid product from the barren leach solution in a second solid/liquid separation” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The instant specification is entirely silent as to “segregating”. The instant specification is entirely silent as to “a second solid/liquid separation”. The instant specification is entirely silent as to “a barren leach solution”. Claims 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected due to their dependence on rejected claim 1.
Regarding claim 1, the claim was amended on 1/16/26 to recite “recycling a thiosulfate-containing fraction of the barren leach solution”. The instant specification does not describe “recycling a thiosulfate-containing fraction of the barren leach solution” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The instant specification is entirely silent as to “a barren leach solution”. Claims 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected due to their dependence on rejected claim 1.
Regarding claim 36, the claim was amended on 1/16/26 to recite “wherein a concentration of thiosulphate during the step of adding a reductant to precipitate is maintained in a range of between about 2,000 to about 25,000 ppm”. The instant specification does not describe “wherein a concentration of thiosulphate during the step of adding a reductant to precipitate is maintained in a range of between about 2,000 to about 25,000 ppm” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The instant specification teaches that “such precipitation step carried out on the leached solution is carried out while the concentration of thiosulphate is maintained in a range of between about 2,000 to about 21,000 ppm, including any value or subrange therebetween, e.g. about 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000 or 20,000 ppm” (paragraph [0129). The instant specification is entirely silent as to “a range of between about 2,000 to about 25,000 ppm thiosulphate”.
Regarding claim 50, the claim was added on 1/16/26 to recite “wherein the thiosulphate generating pH is maintained at or above pH 9”. The instant specification does not describe “wherein the thiosulphate generating pH is maintained at or above pH 9” in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. The instant specification teaches that “the thiosulphate leaching process is carried out at a pH in the range of about 7.5 to about 11, including any value therebetween, e.g. 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8 or 10.9” (paragraph [0107]). The thiosulphate leaching process is step (ii) of claim 1, not step (i). The instant specification is entirely silent as to a minimum pH during the step of thiosulphate generating.
Claims 23 and 28 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor, or for pre-AIA the applicant regards as the invention.
Claim 23 recites the limitation " the first reductant". There is insufficient antecedent basis for this limitation in the claim.
Claim 28 recites the limitation " the first reductant". There is insufficient antecedent basis for this limitation in the claim.
Claims 16 and 28 are rejected under 35 U.S.C. 112(d) as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends.
Regarding claim 16, claim 16 depends from claim 1. Claim 1 recites “a thiosulfate generating oxidation-reduction potential (ORP) is maintained by addition of the oxidant at equal to or greater than -80 mV vs. Ag/AgCI”. Claim 16 recites “wherein the oxidant comprises oxygen (02); wherein the oxidant is supplied to the reaction mixture at a rate that maintains an oxidation-reduction-potential (ORP) in the range of about -80 mV to about 100 mV (Ag/AgCI); and/or wherein the oxidant is supplied to the reaction mixture at a rate of between about 0.35 to about 0.55 tonnes of oxidant per tonne of sulphur that is to be oxidized to thiosulphate”. Claim 16 provides three alternatives, only one of which must be true, and one is already included in claim 1. Accordingly, claim 16 fails to further limit the claim upon which it depends. Applicant may cancel the claim(s), amend the claim(s) to place the claim(s) in proper dependent form, rewrite the claim(s) in independent form, or present a sufficient showing that the dependent claim(s) complies with the statutory requirements.
Regarding claim 28, claim 28 depends from claim 1. Claim 1 recites “adding a reductant comprising one or more of copper concentrate, ferrous sulphate (FeSO4) and sodium hydrosulphide (NaSH) to the pregnant leaching solution”. Claim 28 recites “adding a scavenging precipitant after adding the first reductant to the leached solution; optionally wherein the scavenging precipitant comprises NaSH, optionally wherein the NaSH regenerates thiosulphate when added to the leached solution”. The instant specification states “precipitation may be conducted with a first reductant as described above, wherein the first reductant is not NaSH, and then a small amount of NaSH may be added as a scavenging precipitant to further increase the percentage of metal values precipitated out of the leached solution and/or to regenerate thiosulphate for recycling to the leaching reaction mixture” (paragraph [0121]). Accordingly, the instant specification teaches that when NaSH may be added as a scavenging precipitant, NaSH is not the first reductant. Accordingly, claim 28 fails to include all the limitations upon which it depends. Applicant may cancel the claim(s), amend the claim(s) to place the claim(s) in proper dependent form, rewrite the claim(s) in independent form, or present a sufficient showing that the dependent claim(s) complies with the statutory requirements.
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 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.
Language from the reference(s) is shown in quotations. Limitations from the claims are shown in quotations within parentheses. Examiner explanations are shown in italics.
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.
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 set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied 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, 7, 12, 14, 16, 19, 23, 28, 33, 36-37, and 44-50 are rejected under 35 U.S.C. 103 as being unpatentable over Aylmore et al. (WO 2004005556 A1), in view of Hackl et al. (US 20040115108 A1) and Xia et al. (US 20100025259 A1).
Regarding claims 1, 12, 16, 33, 45, and 50, Aylmore teaches “a process for leaching precious metals from an ore” (which reads upon “a method for recovering precious metal values and/or copper”, as recited in the instant claim; page 1). Aylmore teaches that “the present invention is based on the discovery that sufficient thiosulfate ions to leach precious metals can be generated in situ when a particulate ore such as a sulfide ore is exposed to a suitable source of oxygen in an alkaline aqueous environment” (which reads upon “from a sulphidic starting material comprising the steps of”, as recited in the instant claim; page 2). Aylmore teaches “contacting the milled ore with water, an alkaline reagent, a suitable source of oxygen and a suitable source of sulfur in amounts sufficient to generate at least 0.02 mol/L thiosulfate in situ, and leaching the milled ore into an aqueous thiosulfate phase” (which reads upon “(i) mixing the starting material with an oxidant and a base in a reaction mixture so as to generate thiosulphate by alkaline oxidation of the starting material, (ii) allowing the thiosulphate to complex the precious metal values and/or copper in a leaching solution, in the presence of a leaching concentration of thiosulphate that is maintained at or above 2 g/L”, as recited in the instant claim; page 2; an alkaline reagent reads on a base; 0.02 mol/L thiosulfate times 112 g/mol = 2.24 g/L thiosulfate). Aylmore teaches that “in a typical embodiment of the invention, the pH will be in the range of 9.5 to 10.5” (which reads upon “wherein a thiosulphate generating pH is maintained at or above pH 7.5 by addition of the base”, as recited in the instant claim; which reads upon claims 12, 33, and 50; page 4). Aylmore teaches that “the leaching step of the present invention may take place at a temperature of up to 70°C” (which reads upon “a thiosulfate generating temperature is maintained at less than 100 °C”, as recited in the instant claim; pages 5-6). Aylmore teaches that “any suitable alkaline reagent may be used, such as ammonia, lime, sodium hydroxide, potassium hydroxide, soda ash or potash, or a mixture thereof” (page 4; ammonia is optional). Aylmore teaches that Examples 2 and 4 do not use ammonia (which reads upon “wherein the leaching is conducted without the addition of ammonia”, as recited in the instant claim; pages 9-12). Aylmore teaches that “overall 70% of the gold has been leach from the ore without the addition of copper, ammonia or thiosulfate” (which reads upon “wherein the leaching is conducted without the addition of ammonia”, as recited in the instant claim; page 12). Aylmore teaches that “the liquor was removed from the solid by filter press and the residue washed with water” (which reads upon “(iii) segregating the liquid leaching solution from a solid leach residue in a first solid/liquid separation to produce a pregnant leaching solution”, as recited in the instant claim; page 12). Aylmore teaches that “a second and then a third leach were carried out on the residue in the same way as in the first, for a further 3 -hour period” (which reads upon “(v) segregating the solid product from the barren leach solution in a second solid/liquid separation”, as recited in the instant claim; page 12).
Aylmore is silent regarding an oxidation-reduction potential (ORP). Aylmore is silent regarding a thiosulfate generating oxidation-reduction potential (ORP) is maintained by addition of the oxidant at equal to or greater than -80 mV vs. Ag/AgCI. Aylmore teaches that “copper acts as a catalyst by increasing gold dissolution rates in the presence of thiosulfate” (page 5). Aylmore teaches that “the leaching is conducted in the presence of copper” (page 5). Aylmore is silent regarding the addition of copper sulphate so that a leaching concentration of copper in the leaching solution is maintained at or above 10 ppm. Aylmore is silent regarding (vi) recycling a thiosulfate-containing fraction of the barren leach solution to the step of mixing the starting material with the oxidant and the base.
Hackl is similarly concerned with recovering precious metals from refractory materials using thiosulfate lixiviants (abstract). Hackl teaches that “thiosulfate can be generated in situ” (which reads upon “to generate thiosulphate”, as recited in the instant claim; paragraph [0046]). Hackl teaches that “the dissolved molecular oxygen content of the lixiviant ranges from about 1 to about 50 mg/L, and more preferably from about 3 to about 40 mg/L” (which reads upon “oxidant”, as recited in the instant claim; paragraph [0018]). Hackl teaches that “the near-absence or complete absence of copper and ammonia in the leach can provide for a much more reliable and robust leaching process, yielding more stable leachates, able to operate over a wider pH and oxidation-reduction potential (ORP) range than is possible with conventional thiosulfate leaching, and that the latter process must operate in the relatively narrow window of pH and ORP where both the cupric ammine complex and the gold thiosulfate complex co-exist” (paragraph [0022]; controlling copper concentration, pH, and ORP). Hackl teaches that “maximum precipitation of gold and regeneration of thiosulfate is accomplished by adding at least a stoichiometric amount of sulfide reagent 162 (relative to the dissolved precious metal and polythionate concentrations) to reduce the solution ORP to at least about 50 mV (SHE)” (paragraph [0069]; minimum ORP given in SHE basis, rather than Ag/AgCl basis). Hackl teaches that the “tables clearly show that when air is applied to a column, the dissolved oxygen level and Oxidation-Reduction Potential or ORP both increase, and that this results in an increase in gold extraction” (paragraph [0121] and Tables 1 and 2). Tables 1 and 2 of Hackl show that to achieve at least 60% extraction, ORP Ag/AgCl must be at least -1 mV and dissolved O2 must be at least 3.3 mg/L (which reads upon “a thiosulfate generating oxidation-reduction potential (ORP) is maintained by addition of the oxidant at equal to or greater than -80 mV vs. Ag/AgCI”, as recited in the instant claim; which reads upon claim 45; Tables 1 and 2). Hackl teaches that “the base 120, thiosulfate lixiviant 122, copper 124, and binder 128 are incorporated into the agglomerate matrix” (paragraph [0039]). Hackl teaches that “preferably, the copper 124, when added, is the form of a copper sulfate, copper oxide, copper nitrate, copper chloride, and mixtures thereof” (which reads upon “with the addition of copper sulphate”, as recited in the instant claim; paragraph [0041]). Hackl teaches that “the preferred mass ratio of the copper ion to thiosulfate ion is preferably from about 1:10 to about 1:1000” (which reads upon “so that a leaching concentration of copper in the leaching solution is maintained at or above 10 ppm”, as recited in the instant claim; paragraph [0041]; 0.02 mol/L thiosulfate divided by 10 to 1000 = 0.002 to 0.00002). Hackl teaches that “sufficient copper may be added to catalyze the leaching reaction when necessary to realize desired rates of precious metal recovery” (paragraph [0041]). Hackl teaches that “the conditioned recycle solution 144 is the product of conditioning the recycled barren lixiviant 150” (which reads upon “(vi) recycling a thiosulfate-containing fraction of the barren leach solution”, as recited in the instant claim; paragraph [0046]). Hackl teaches that “the thiosulfate lixiviant 122 is made by recharging the conditioned recycle solution 144” (paragraph [0046]). Hackl teaches that “the thiosulfate lixiviant 122 is contacted with the comminuted precious metal-bearing material 108 before or during agglomeration 112” (which reads upon “(vi) recycling a thiosulfate-containing fraction of the barren leach solution to the step of mixing the starting material with the oxidant and the base”, as recited in the instant claim; paragraph [0046] and FIG. 1 which shows recycled barren lixiviant 150 being recycled to agglomeration 112).
Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Aylmore to control the ORP Ag/AgCl to at least -1 mV, as taught by Hackl to improve extraction rates. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Aylmore to add copper sulphate such that the mass ratio of the copper ion to thiosulfate ion is preferably from about 1:10 to about 1:1000, as taught by Hackl because Aylmore teaches that the leaching is conducted in the presence of copper, but does not specify the source or the amount of copper. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Aylmore to add recycling the barren lixiviant, as taught by Hackl to avoid environmental issues with waste thiosulfate.
Modified Aylmore is silent regarding (iv) adding a reductant comprising one or more of copper concentrate, ferrous sulphate (FeSO4) and sodium hydrosulphide (NaSH) to the pregnant leaching solution to precipitate the precious metal values and/or copper as a solid product and to produce a barren leach solution.
Xia is similarly concerned with a method of recovering silver and gold from leachates of thiosulfate ions and/or thiocyanate ions (paragraph [0002]). Xia teaches that “prior to performing the precious metal co-precipitation method on a pregnant leachate, any fine particulate matter is preferably removed, for example, by filtration” (which reads upon “(iii) segregating the liquid leaching solution from a solid leach residue in a first solid/liquid separation to produce a pregnant leaching solution”, as recited in the instant claim; paragraph [0055]). Xia teaches that “the ferrous salt(s) is dissolved in water and the resulting aqueous solution is added to the pregnant solution” (which reads upon “(iv) adding a reductant to the pregnant leaching solution”, as recited in the instant claim; paragraph [0049]). Xia teaches that “ferrous salts that are useful in this method include any ferrous salt that is reasonably soluble in aqueous solution, such as, for example, ferrous sulfate” (which reads upon “(iv) adding a reductant comprising one or more of copper concentrate, ferrous sulphate (FeSO4) and sodium hydrosulphide (NaSH) to the pregnant leaching solution”, as recited in the instant claim; paragraph [0061]; ferrous sulfate reads on ferrous sulphate). Xia teaches that “the precious metal recovery method described herein provides a co-precipitation wherein an aqueous solution of ferrous salt(s) is combined with an aqueous solution that contains precious metal ions and hydroxide ions, and that at the time that ferrous ions encounter the precious metal ions, a co-precipitate forms that is made up of precious metal in solid form and iron hydroxides and/or iron oxides” (paragraph [0048]). Xia teaches that “the reaction is rapid and substantially all of the precious metal ions from the pregnant solution are recovered in solid form” (which reads upon “to precipitate the precious metal values and/or copper as a solid product and to produce a barren leach solution”, as recited in the instant claim; paragraph [0048]). Xia teaches that “this method is suitable for recovering precious metals from solutions such as leachates in which they are present in low, or even very low, concentrations, and that leachates may contain thiocyanates, thioureas, halogens, thiosulfates, or combinations thereof” (paragraph [0048]).
Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Aylmore to add a ferrous salt, such as ferrous sulfate, dissolved in water, to the pregnant solution, as taught by Xia because this method is suitable for recovering precious metals from solutions such as leachates in which they are present in low, or even very low, concentrations, the reaction is rapid, and substantially all of the precious metal ions from the pregnant solution are recovered in solid form.
Regarding claim 7, modified Aylmore teaches the method of claim 1 as stated above. Aylmore teaches “a process for leaching precious metals such as gold from an ore such as a sulphide ore” (abstract).
Regarding claim 14, modified Aylmore teaches the method of claim 1 as stated above. Aylmore teaches that “the ore of Example 1 was ground in a batch 1.4 litre attritor mill for 5 hours under either mixtures of oxygen and 0.3M NaOH or 0.4M ammonia-oxygen and 0.15M NaOH in solution” (page 11).
Regarding claim 19, modified Aylmore teaches the method of claim 1 as stated above. Aylmore teaches that “although the leaching step of the present invention may take place at a temperature of up to 70°C, it can be performed at slightly elevated temperatures (up to 50°C) or even at ambient temperature” (pages 5-6; overlapping ranges). Aylmore teaches that “although the leaching step can be conducted at slightly elevated pressures, it is suitably conducted at atmospheric pressure” (page 6).
Regarding claim 23, modified Aylmore teaches the method of claim 1 as stated above. Hackl teaches that “sulfide precipitation not only precipitates the precious metal but also precipitates transition metals, such as copper, and regenerates the thiosulfate by converting polythionates into thiosulfate” (paragraph [0063]). Xia teaches that “the aqueous solution may further contain copper ions, and that the step of purifying elemental precious metal may comprise treating the solid containing precious metal with a copper complexing agent and removing the resulting copper complex” (paragraph [0024]).
Regarding claim 28, modified Aylmore teaches the method of claim 1 as stated above. Hackl teaches that “a sulfite reagent can also be used for thiosulfate regeneration” (paragraph [0029]). Hackl teaches that “the first processing step 160 is sulfide precipitation of the dissolved precious metals using a sulfide reagent 162 to form a precipitate-containing slurry 164, and that sulfide precipitation not only precipitates the precious metal but also precipitates transition metals, such as copper, and regenerates the thiosulfate by converting polythionates into thiosulfate” (paragraph [0063]). Hackl teaches that “sufficient sulfide is added to the pregnant leach solution 138 to precipitate at least most of the dissolved precious and transition metal(s) as sulfides and to convert at least most of the polythionates to thiosulfate, more preferably to precipitate at least about 99% of the precious and transition metals and convert at least about 90% of the polythionates to thiosulfate, effectively regenerating the thiosulfate lixiviant” (paragraph [0068]). Hackl teaches that “the regeneration phase of the conditioning step 182 can be performed in a variety of locations; for example, regeneration phase can be performed in the recycle loop before or after fresh thiosulfate 148 addition and before comminution 200, between comminution 200 and thickening 208, in the thickener, and/or immediately before or during leaching 220” (paragraph [0126]).
Regarding claim 36, modified Aylmore teaches the method of claim 1 as stated above. Aylmore teaches “contacting the milled ore with water, an alkaline reagent, a suitable source of oxygen and a suitable source of sulfur in amounts sufficient to generate at least 0.02 mol/L thiosulfate in situ, and leaching the milled ore into an aqueous thiosulfate phase” (page 2). 0.02 mol/L = 20,000 ppm.
Regarding claim 37, modified Aylmore teaches the method of claim 1 as stated above. Aylmore teaches that “although the leaching step can be conducted at slightly elevated pressures, it is suitably conducted at atmospheric pressure” (page 6).
Regarding claims 44 and 47-49, modified Aylmore teaches the method of claim 1 as stated above. Aylmore teaches that “the pyrite concentrate was milled for up to 1.5 hours” (page 13). Aylmore teaches that “evidence of gold and silver dissolution from thiosulfate generated from the leaching of ultra fine milled pyrite concentrate in oxygen at a pH of 9.5 is shown in Figure 2A” (page 10).
Regarding claim 46, modified Aylmore teaches the method of claim 1 as stated above. Aylmore teaches that “the thiosulfate generated in situ constitutes from 30% to 100% of the thiosulfate present in the aqueous phase, more preferably 50% to 100% and most preferably 80% to 100%” (page 2).
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/REBECCA JANSSEN/Primary Examiner, Art Unit 1733
