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WO2015102865A1 - Procédé de dissolution ou d'extraction d'au moins un métal précieux d'une matière source le contenant - Google Patents

Procédé de dissolution ou d'extraction d'au moins un métal précieux d'une matière source le contenant Download PDF

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Publication number
WO2015102865A1
WO2015102865A1 PCT/US2014/070325 US2014070325W WO2015102865A1 WO 2015102865 A1 WO2015102865 A1 WO 2015102865A1 US 2014070325 W US2014070325 W US 2014070325W WO 2015102865 A1 WO2015102865 A1 WO 2015102865A1
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Prior art keywords
solvated
solution
sodium
source
metal
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PCT/US2014/070325
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English (en)
Inventor
Thanikavelu Manimaran
Joseph O'DAY
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Albemarle Corporation
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Publication of WO2015102865A1 publication Critical patent/WO2015102865A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B11/00—Obtaining noble metals
    • C22B11/04—Obtaining noble metals by wet processes

Definitions

  • This invention relates to hydrometallurgical processing involving extraction of at least one precious metal in a dissolved form from a source material containing such metal(s). At least one base metal may also be extracted from such source material.
  • DBDMH l,3-dibromo-5,5-dimethylhydantoin
  • compositions have rather high freezing points, so that freezing can be a problem even at relatively moderate temperatures.
  • low water solubility poses potential problems associated with precipitation or crystal formation in, or freezing of, aqueous systems containing DBDMH when used in cold climates.
  • Still another objective of this invention is to provide a new way of regenerating used leachant solutions, i.e., solutions which have already been used to remove or extract one or more metals, preferably at least one precious metal, from its source material.
  • used leachant solutions i.e., solutions which have already been used to remove or extract one or more metals, preferably at least one precious metal, from its source material.
  • This invention is effective for recovery of precious metals such as gold, palladium, silver, rhodium, or the like in water soluble form from which these precious metals can be conveniently recovered in economically satisfying yields. If appropriate sources containing mixtures of these precious metals exist or become available, the present process technology is deemed capable of recovering such metals, while at the same time providing aqueous solutions or slurries from which other precious metals (e.g. , platinum, osmium, iridium or the like) and/or base metals may be recovered by this or other suitable processing.
  • precious metals such as gold, palladium, silver, rhodium, or the like
  • this invention provides the opportunity of effectively fulfilling the above referred to need for improved hydrometallurgical processes for dissolving, leaching, and/or extracting precious metals and desirably base metals as well from a number of suitable sources thereby enabling recovery and isolation of such metals. Additionally, this invention makes possible the utilization of various commercially- available products that are already being produced by a number of industrial concerns for uses unrelated to usage pursuant to this invention. In most cases, only one or two simple low-cost steps readily convert and adapt such products for effective use in the practice of this invention. Thus in such cases, only relatively inexpensive equipment can be used to effect such conversion and adaptation for effective usage.
  • this invention provides effective ways of achieving the above advantages of providing new leaching solutions from which precious leached metal(s) in suitable dissolved forms can be effectively and economically recovered.
  • This invention provides the opportunity to accomplish still another desirable result referred to above, again in an efficient and a cost-effective manner.
  • the desirable result is the possibility of providing ways of also recovering commercially useful base metals associated with the precious metals.
  • a process for extracting at least gold or palladium from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N-halosulfamate source, and (C) at least one solvated alkali metal halide and/or at least one solvated alkaline earth metal halide, and/or at least one solvated ammonium halide.
  • C is one of the following:
  • At least one precious metal is extracted into a dissolved form of at least one of said precious metals. It is also possible for at least one base metal to be extracted.
  • alkali metal sulfamates include sodium sulfamate; preferred combinations of alkali metal sulfamates include sodium sulfamate and potassium sulfamate.
  • the alkali metal sulfamates are in solvated form.
  • compositions comprising at least one precious metal in the form of a solute in an aqueous medium comprising at least one solvated N- halosulfamate source, and any one of the foregoing seven compositions of (C).
  • a process for producing an aqueous dissolving, leaching, or extracting solution containing at least one precious metal comprising contacting a source of such precious metal with an aqueous leaching solution comprising (i) water, (ii) at least one solvated N-halosulfamate source, and (iii) at least one solvated alkali metal halide and/or at least one solvated alkaline earth metal halide and/or at least one solvated ammonium halide, whereby during the process at least one of said precious metals is extracted into a dissolved form of that precious metal.
  • (ii) is either at least one solvated N- bromosulfamate source, or at least one solvated N-bromosulfamate source and at least one solvated N-chlorosulfamate source.
  • the N-halosulfamate source can be at least one solvated N-chlorosulfamate source or at least one solvated N-chlorosulfamate source in combination with at least one solvated N-iodosulfamate source or at least one solvated N-fluorosulfamate source.
  • (ii) can be or include at least one solvated N- iodosulfamate source or at least one solvated N-fluorosulfamate source.
  • Other combinations can be at least one solvated N-bromosulfamate source and at least one solvated N-iodosulfamate source; at least one solvated N-bromosulfamate and at least one solvated N-fluorosulfamate; or at least one solvated N-iodosulfamate source and at least one solvated N-fluorosulfamate.
  • Still further combinations can be at least one solvated N- bromosulfamate, at least one solvated N-chlorosulfamate, and at least one solvated N- iodosulfamate; at least one solvated N-bromosulfamate, at least one solvated N- chlorosulfamate, and at least one solvated N-fluorosulfamate; at least one solvated N- bromosulfamate, at least one solvated N-iodosulfamate, and at least one solvated N- fluorosulfamate; at least one solvated N-chlorosulfamate, at least one solvated N- iodosulfamate, and at least one solvated N-fluorosulfamate.
  • the combination can be at least one solvated N-bromosulfamate, at least one solvated N-chlorosulfamate, at least one solvated N-iodosulfamate, and at least one solvated N-fluorosulfamate.
  • the halogen atoms of (i) the halosulfamate source and of (ii) the alkali metal halides and/or (iii) the alkaline earth metal halides and/or (iv) the ammonium halides in the above processes and in the above compositions are preferably chlorine, bromine and/or iodine atoms, with bromine atoms alone or in combination with chlorine atoms being more preferred. It is possible for fluorine atoms to be present.
  • iodine and/or fluorine atoms When iodine and/or fluorine atoms are present, it is preferred that atoms of at least one other halogen are also present and that the total number of fluorine atoms is less than the total number of the other halogen atoms.
  • Preferred alkali metal halides and/or alkaline earth metal halides and/or ammonium halides which are typically in solvated form, include
  • combinations comprising (a) at least one bromide selected from alkali metal bromides and/or ammonium bromides and/or alkaline earth metal bromides, and/or combinations of any two or all three of these, and (b) at least one chloride selected from alkali metal chlorides and/or ammonium chlorides and/or alkaline earth metal chlorides, and/or combinations of any two or all three of these.
  • the N-halosulfamate in the aqueous leaching solution comprises N-bromosulfamate
  • the alkali metal halides and/or alkaline earth metal halides and/or ammonium halides comprise alkali metal bromides and/or ammonium bromides and/or alkaline earth metal bromides, and/or combinations of any two or all three of these
  • the aqueous leaching solution is a bromine-containing solution that is chlorine-free, iodine-free, and fluorine-free, and also chloride-free, iodide-free, and fluoride-free.
  • the N-halosulfamate in the aqueous leaching solution comprises N-bromosulfamate
  • the alkali metal halides and/or alkaline earth metal halides and/or ammonium halides comprise combinations comprising (a) at least one bromide selected from alkali metal bromides and/or ammonium bromides and/or alkaline earth metal bromides, and/or combinations of any two or all three of these, and (b) at least one chloride selected from alkali metal chlorides and/or ammonium chlorides and/or alkaline earth metal chlorides, and/or combinations of any two or all three of these
  • the aqueous leaching solution is a bromine- and chlorine-containing solution that is fluorine- free and iodine-free and also fluoride-free and iodide-free.
  • the terms “dissolve”, “dissolving”, “dissolved”, etc. , “leach”, “leaching”, “leachant”, etc. , and “extract” (as a verb), “extracting”, “extract” (as a noun), etc. , are used interchangeably. It matters not whether the extracting or leaching solution is quiescent, under agitation, or passing over and/or through the precious metal-containing source material being treated. Naturally, at least a portion of the precious metal in the precious metal-containing source material should be capable of being contacted by the leaching (extracting) solution.
  • At least a portion of the precious metal should be susceptible to leaching (extracting) by contact with the leaching (extracting) solution being used.
  • pretreatment such as grinding, milling or other forms of mechanical subdividing of the precious metal- containing source may be used to expose surfaces of precious metal in its source material for contact by the leaching (extracting) solution to be used.
  • pretreatment with acids or the like may be used to achieve this same objective.
  • Still other methods of rendering the precious metal in its own source material accessible to leaching (extraction) through contact by the leaching (extracting) solution are known and can be used if necessary or desirable.
  • at least one precious metal in its source material used should be leachable (extractable).
  • Another way of achieving good leaching (extraction) of precious metal from its source material is to select a precious metal source material from which suitable amounts of precious metal can be leached (extracted) without any pretreatment to make this possible.
  • this discussion about leaching (extraction) of precious metal does not signify that the precious metal is to be leached (extracted) in solution as a free metal. This may possibly occur in some cases, but in other cases the precious metal leachant (extract) can be in the form of a complex or other chemical entity that is not simply pure dissolved precious metal in ionic form. The end result is in effect the same because, in either case, the precious metal in some kind of dissolved form is removed from the rest of the source material.
  • This invention involves two different types of leaching solutions.
  • One is the dilute leaching solution used at the site of the precious metal recovery operation.
  • the other is a concentrated solution such as are available commercially for uses other than that of the present invention or which may be produced on site of the precious metal recovery or may be produced elsewhere and in any such case, stored for usage as needed.
  • dilute aqueous solutions that may be formed and used pursuant to this invention that comprise at least one solvated N-halosulfamate and at least one solvated alkali metal halide, and/or at least one solvated ammonium halide, and/or at least on alkaline earth metal halide, where the halogen atoms are preferably CI and/or Br and/or I, but may be or include F atoms.
  • the atomic ratio of halogen from sulfamate(s) to total halide ions from alkali metal halide(s) and/or ammonium halide(s) and/or alkaline earth metal halide(s) is typically in the range of about 1: 1 to about 1:20, and preferably in the range of about 1 : 1 to about 1:3.
  • the atomic ratio of halide ions from sulfamate(s) to total halide ions from alkali metal halide(s), one or more ammonium halides and alkaline earth metal halide(s) is typically in the same ratios as given above. This is accomplished by suitably proportioning the total number of active halogen atoms from the halosulfamates to the total number of halide atoms from the alkali metal halide(s), ammonium halide(s) and the alkaline earth metal halides(s). [0027] In the case of the concentrated solutions, the halogen atom ratios will be in the same ranges as given above for the dilute solutions.
  • the amount of N-halosulfamate in the concentrated and dilute solutions will vary depending upon a number of factors.
  • the active halogen concentration of dissolved N- halosulfamate can vary from as little as 0.5 grams/liter of water up to 100 grams per liter or even more depending upon the precious metal content of the precious metal source being used, the temperature of the solutions, the character of the precious metal source material, the particular leaching solution of this invention being used, the pretreatment if any and physical condition of the precious metal source being used, the amount of leaching solution being used, and the like.
  • a few simple small scale trial experiments with different specified concentrations of the N-halosulfamate leaching solution of this invention should enable determination of desirable concentrations for use in a larger scale operation.
  • any suitable concentration can be used taking into consideration shipping costs, if any, are involved, storage space available for use, quantities of precious metal source material to be processed and projected rates of precious metal source material usage are among factors of interest.
  • Leaching solutions of this invention to be used for recovery of precious metals from low grade ores should contain at least about 0.05 wt preferably at least about 0.1 wt of the leaching agent.
  • the amount sufficient to leach gold from a leachable gold source and the amount required for leaching palladium from a leachable palladium source will be in about the same range of about 0.05 wt to about 10 wt of active bromine and more preferably in the range of about 0.05 wt to about 5 wt .
  • a stronger leaching solution is preferably used, for example, one containing between about 2 pounds and about 10 pounds of leaching agent per ton of solution or between about 1 and about 10 grams per liter.
  • a high grade source is one in which the metal to be recovered is present in a weight proportion of greater than 1%, and the metal to be extracted is accessible to the leaching solution without the necessity of chemically degrading non-metallic contaminants.
  • the rate at which gold is dissolved in an extracting or leaching solution of this invention tends to be faster than the rate at which palladium dissolves in such solution. Therefore when extracting both gold and palladium from one or more suitable source materials, it is desirable to take into consideration the apparent slower rate of dissolution of palladium as compared to that of gold by providing sufficient time for a high quantity of palladium to go into solution.
  • the total respective exposed areas of the respective precious metals in the source material(s) being employed is also of importance. In general, the greater the total surface area of the precious metal exposed to the extracting or leaching solution, the greater will be the amount of dissolution of that precious metal.
  • the bromine: chlorine atom ratio is preferably at least about 1: 1.
  • the aqueous leaching solution contains in the range of about 0.01% to about 20% and preferably in the range of about 0.1% to about 5% by weight equivalent molecular bromine, the solution also contains in the range of about 0.01% to about 20% and preferably in the range of about 0.1% to about 5% by weight bromide ion, and in the range of about 0.01% to about 30% preferably in the range of about 0.1% to about 10% by weight total halide ion.
  • Another aspect of this invention is a process for extracting at least one precious metal , and/or a base metal from a source material containing said metal, the process comprising contacting said source material with an aqueous leaching solution containing a leaching agent comprising a solvated alkali metal halosulfamate, thereby producing an aqueous leachate-containing said metal in dissolved form.
  • the alkali metal is preferably lithium, sodium, and/or potassium. Of these, sodium and/or potassium are more preferred.
  • the halogen atoms of the alkali metal halosulfamate is preferably bromine, but chlorine, iodine, and/or fluorine may be the halogen atom.
  • alkali metal halosulfamates Mixtures of any two or more of the foregoing 12 alkali metal halosulfamates can be used, as well.
  • a preferred alkali metal halosulfamate is sodium bromosulfamate.
  • a preferred mixture of alkali metal halosulfamates is a mixture of sodium bromosulfamate and sodium chlorosulfamate.
  • a process for recovery of at least one precious metal , or a base metal in metallic form comprising direct current electrolysis of an electrowinning solution containing at least one N-halosulfamate compound and anions comprising a metal complexed with halogens derived from the reaction of the N-halosulfamate compound with the metal whereby during the process the precious metal or base metal in metallic form is produced and electrodeposited.
  • Deposition of a base metal separates it from the precious metal and thus provides a more concentrated form of the precious metal as well as the recoverable base metal.
  • Also included in the invention is a process for electrodeposition of a precious metal , or a base metal.
  • the process comprises direct current electrolysis of an electrolytic solution containing (i) a dissolved N-halosulfamate source and anions comprising the metal complexed with halogens, especially bromine or bromine and chlorine atoms, whereby during the process the precious metal or the base metal are electrodeposited.
  • aqueous solvated solutions of N-halosulfamate by mixing with water (a) sulfamic acid and/or (b) one or more alkali metal halide salts, and/or one or more ammonium halide salts and/or one or more alkaline earth metal salts of sulfamic acid.
  • the alkali metal halide, and/or alkaline earth metal halide and/or ammonium halide can be added before or after the addition of the sulfamic acid or salts thereof referred to in (a) or (b) above. Also, they may be added concurrently.
  • N-halosulfamate can be pre-formed or generated in-situ by chemical or electrolytic oxidation of halides in presence of sulfamate.
  • the source of sulfamate could be from used lixiviant or a used aqueous leaching solution so that an active lixiviant or an active aqueous leaching solution is regenerated.
  • Some of the chemical oxidants for bromide oxidation include potassium
  • Figures 1-21 are graphs of, or relate to, experimental data, a more specific explanation or description of which accompanies or is provided with each Figure.
  • this invention utilizes aqueous solutions comprising aqueous solutions of solvated N-bromosulfamates or aqueous solutions of combinations of solvated N-bromosulfamates and solvated N-chlorosulfamates and/or aqueous solutions of solvated N-iodosulfamates alone or in combination with either or both of solvated N- bromosulfamates alone or solvated N-bromosulfamates together with solvated N- chlorosulfamates in combination with solvated alkali metal halides and/or solvated alkaline earth metal halides. It is realized that if water is the sole solvent, the solvated substances can be referred to as "hydrated.”
  • This invention provides a number Groups of individual novel processes or compositions, including the following:
  • a process for extracting at least one precious metal from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N- bromosulfamate source, and (C) at least one solvated alkali metal halide, or at least one solvated alkaline earth metal halide, or at least one solvated ammonium halide, or any two or more of the foregoing solvated halides.
  • a process for extracting at least one precious metal from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N-bromosulfamate source, (C) at least one solvated alkali metal halide, or at least one solvated alkaline earth metal halide, or at least one solvated ammonium halide, or any two or more of the foregoing solvated halides, and (D) at least one solvated N-chlorosulfamate source.
  • (B) and (D) are proportioned such that the active halogen atom ratio of solvated N-bromosulfamate source: solvated N- chlorosulfamate source is in the range of about 1:1 to 10:1.
  • a process for extracting at least one precious metal from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N-bromosulfamate source, and (C) at least one solvated potassium halide.
  • a process for extracting at least one precious metal from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N-bromosulfamate source, and (C) at least one solvated sodium halide and at least one solvated potassium halide.
  • a process for extracting at least one precious metal from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N-bromosulfamate source, and (C) at least one solvated sodium halide.
  • a process for extracting at least one precious metal from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N-bromosulfamate source, (C) at least one solvated sodium halide, and (D) at least one solvated N-chlorosulfamate source.
  • (B) and (D) are proportioned such that the active halogen atom ratio of solvated N-bromosulfamate source:solvated N-chlorosulfamate source is in the range of about 1:1 to 10:1.
  • a process for extracting at least one precious metal from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N-bromosulfamate source, (C) at least one solvated potassium halide, and (D) at least one solvated N-chlorosulfamate source.
  • (B) and (D) are proportioned such that the active halogen atom ratio of solvated N-bromosulfamate source:solvated N-chlorosulfamate source is in the range of about 1:1 to 10:1.
  • a process for extracting at least one precious metal from a source material containing at least one said metal comprising contacting said source material with an aqueous leaching solution comprising (A) water, (B) at least one solvated N-bromosulfamate source, (C) at least one solvated sodium halide and at least one solvated potassium halide, and (D) at least one solvated N-chlorosulfamate source.
  • (B) and (D) are proportioned such that the active halogen atom ratio of solvated N-bromosulfamate source: solvated N-chlorosulfamate source is in the range of about 1:1 to 10: 1.
  • a process as in 9) wherein said precious metal comprises gold, palladium, silver, or rhodium or any mixture of any two or more of these metals.
  • a composition comprising at least one precious metal in the form of a solute in an aqueous medium, the composition comprising (A) water, (B) at least one solvated N-bromosulfamate source, and (C) at least one solvated alkali metal halide, or at least one solvated alkaline earth metal halide, or at least one solvated ammonium halide, or any two or more of the foregoing solvated halides.
  • composition comprising at least one precious metal in the form of a solute in an aqueous medium, the composition comprising (A) water, (B) at least one solvated N- bromosulfamate source, (C) at least one solvated alkali metal halide, or at least one solvated alkaline earth metal halide, or at least one solvated ammonium halide, or any two or more of the foregoing solvated halides, and (D) at least one solvated N- chlorosulfamate source.
  • (B) and (D) are proportioned such that the active halogen atom ratio of solvated N-bromosulfamate source:solvated N- chlorosulfamate source is in the range of about 1: 1 to 10:1.
  • a composition comprising at least one precious metal in the form of a solute in an aqueous medium, the composition comprising (A) water, (B) at least one solvated N- bromosulfamate source, and (C) at least one solvated potassium halide.
  • a composition comprising at least one precious metal in the form of a solute in an aqueous medium, the composition comprising (A) water, (B) at least one solvated N- bromosulfamate source, and (C) at least one solvated sodium halide and at least one solvated potassium halide.
  • a composition comprising at least one precious metal in the form of a solute in an aqueous medium, the composition comprising (A) water, (B) at least one solvated N- bromosulfamate source, and (C) at least one solvated sodium halide.
  • a composition comprising at least one precious metal in the form of a solute in an aqueous medium, the composition comprising (A) water, (B) at least one solvated N- bromosulfamate source, (C) at least one solvated sodium halide, and (D) at least one solvated N-chlorosulfamate source.
  • (B) and (D) are proportioned such that the active halogen atom ratio of solvated N-bromosulfamate source:solvated N- chlorosulfamate source is in the range of about 1: 1 to 10:1.
  • a composition comprising at least one precious metal in the form of a solute in an aqueous medium, the composition comprising (A) water, (B) at least one solvated N- bromosulfamate source, (C) at least one solvated potassium halide, and (D) at least one solvated N-chlorosulfamate source.
  • (B) and (D) are proportioned such that the active halogen atom ratio of solvated N-bromosulfamate source: solvated N-chlorosulfamate source is in the range of about 1: 1 to 10:1.
  • a composition comprising at least one precious metal in the form of a solute in an aqueous medium, the composition comprising (A) water, (B) at least one solvated N- bromosulfamate source, (C) at least one solvated sodium halide and at least one solvated potassium halide, and (D) at least one solvated N-chlorosulfamate source.
  • (B) and (D) are proportioned such that the active halogen atom ratio of solvated N-bromosulfamate source:solvated N-chlorosulfamate source is in the range of about 1: 1 to 10: 1.
  • a composition as in 9) wherein said precious metal comprises gold, palladium, silver, or rhodium or any mixture of any two or more of these metals.
  • A) forming or obtaining a composition comprising an aqueous medium containing (i) at least one solvated N-halosulfamate compound which is totally in solution or is partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated alkali metal halide, and/or at least one solvated ammonium halide and/or at least one solvated alkaline earth metal halide, or any two or more of the foregoing solvated halides; B) acidifying said composition with a mineral acid to form a lixiviant solution having a pH in the range of about 7.5 + 0.5 or less, and optionally diluting said lixiviant solution with water to provide a diluted solution having a reduced active bromine content sufficient to leach the precious metal from its source; and
  • the leachate is recovered from the remainder of the so-processed composition (i.e., that which is left after such recovery).
  • the source material additionally contains at least one base metal
  • the leachate can also contain at least one base metal in solution.
  • a process for forming a water-soluble form of at least one precious metal comprising:
  • A) forming or obtaining a composition comprising an aqueous medium containing (i) at least one solvated N-bromosulfamate compound and at least one solvated N- chlorosulfamate compound either or both of which are totally in solution or are partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated alkali metal halide and/or at least one solvated ammonium halide and/or at least one solvated alkaline earth metal halide, or any two or more of the foregoing solvated halides;
  • leachate is formed containing said at least one precious metal in solution.
  • leachate is recovered from the remainder of the so-processed composition (i.e. , that which is left after such recovery).
  • the source material additionally contains at least one base metal
  • the leachate can also contain at least one base metal in solution.
  • a process for forming a water-soluble form of at least one precious metal comprising:
  • A) forming or obtaining a composition comprising an aqueous medium containing (i) at least one solvated N-bromosulfamate compound which is totally in solution or is partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated potassium halide (preferably solvated sodium bromide or solvated potassium bromide or solvated ammonium bromide, or a mixture of any two or all three of these);
  • leachate is formed containing said at least one precious metal in solution.
  • leachate is recovered from the remainder of the so-processed composition (i.e. , that which is left after such recovery).
  • the source material additionally contains at least one base metal
  • the leachate can also contain at least one base metal in solution.
  • a process for forming a water-soluble form of at least one precious metal comprising:
  • A) forming or obtaining a composition comprising an aqueous medium containing (i) at least one solvated N-bromosulfamate compound which is totally in solution or is partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated sodium halide and at least one solvated potassium halide;
  • leachate is formed containing said at least one precious metal in solution.
  • leachate is recovered from the remainder of the so-processed composition (i.e. , that which is left after such recovery).
  • the source material additionally contains at least one base metal
  • the leachate can also contain at least one base metal in solution.
  • a process for forming a water-soluble form of at least one precious metal comprising: A) forming or obtaining a composition comprising an aqueous medium containing (i) at least one solvated N-bromosulfamate compound which is totally in solution or is partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated sodium halide;
  • leachate is formed containing said at least one precious metal in solution.
  • leachate is recovered from the remainder of the so-processed composition (i.e. , that which is left after such recovery).
  • the source material additionally contains at least one base metal
  • the leachate can also contain at least one base metal in solution.
  • A) forming or obtaining a composition comprising an aqueous medium (i) containing at least one solvated N-bromosulfamate compound and at least one solvated N- chlorosulfamate compound either or both of which are totally in solution or are partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated potassium halide;
  • leachate is formed containing said at least one precious metal in solution.
  • leachate is recovered from the remainder of the so-processed composition (i.e. , that which is left after such recovery).
  • the source material additionally contains at least one base metal
  • the leachate can also contain at least one base metal in solution.
  • a process for forming a water-soluble form of at least one precious metal comprising: A) forming or obtaining a composition comprising an aqueous medium containing (i) at least one solvated N-bromosulfamate compound and at least one solvated N- chlorosulfamate compound which is totally in solution or is partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated sodium halide and at least one solvated potassium halide;
  • leachate is formed containing said at least one precious metal in solution.
  • leachate is recovered from the remainder of the so-processed composition (i.e. , that which is left after such recovery).
  • the source material additionally contains at least one base metal
  • the leachate can also contain at least one base metal in solution.
  • a process for forming a water-soluble form of at least one precious metal comprising:
  • A) forming or obtaining a composition comprising an aqueous medium containing (i) at least one solvated N-bromosulfamate compound and at least one solvated N- chlorosulfamate compound which is totally in solution or is partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated sodium halide;
  • leachate is formed containing said at least one precious metal in solution.
  • leachate is recovered from the remainder of the so-processed composition (i.e. , that which is left after such recovery).
  • the source material additionally contains at least one base metal
  • the leachate can also contain at least one base metal in solution.
  • XII A process as in IX) wherein the precious metal is gold or palladium or both, wherein the aqueous leaching solution has dissolved therein as a solution a precious metal selected from gold or palladium or both, and at least one dissolved metal other than gold or palladium, wherein (B) comprises at least one solvated N- bromosulfamate source, wherein (C) comprise solvated sodium bromide or solvated ammonium bromide or solvated alkaline earth metal bromide or a combination of any two or all three of these, and wherein the solution has a pH in the range of about 4 to about 6.
  • (C) can be only "at least one solvated ammonium halide", or can include "at least one solvated ammonium halide”.
  • aqueous lixiviant or extracting solutions of this invention comprise water containing solvated sodium bromosulfamate and solvated sodium bromide. These solutions have shown the best overall performance and product characteristics. These solutions are sometimes referred to hereinafter as "Stabilized Bromine" in recognition of the enhanced stability characteristics which they possess.
  • Still another embodiment of this invention is a process for dissolving at least one precious metal from a material containing or composed of at least one said precious metal in leachable form and optionally at least one base metal in leachable form, and/or leaching at least one said precious metal in leachable form from a source material comprising at least one precious metal, the process comprising the steps of: A) forming or obtaining (i.e., providing) a composition comprising (i) an aqueous medium containing (i) at least one solvated N-halosulfamate compound which is totally in solution or is partially in solution and partially in the form of crystals or particles in said aqueous medium, and (ii) at least one solvated alkali metal halide, and/or at least one solvated ammonium halide and/or at least one solvated alkaline earth metal halide (preferably where the halogen of said halosulfamate compound and of said metal halide being, independently, bromine, chlorine, or
  • a lixiviant solution having a pH in the range of about 7.5 + 0.5 or less (preferably a pH in the range of about 4 to about 6 for gold and/or palladium, and preferably a pH in the range of about 1 or less for silver and/or rhodium), and optionally diluting said lixiviant solution with water to provide a diluted lixiviant solution having a reduced active bromine content sufficient to leach the precious metal from its source; and
  • Temperatures used in the leaching (extraction) operations of this invention can vary provided that under the pressure conditions at which the process is conducted, the leaching solution contains enough liquid water to enable leaching to occur. Desirably, however, temperatures of the leaching solution when in use are in the range of about ambient room temperature to about 60°C. Pressures may be atmospheric, autogenous, sub-atmospheric, or super-atmospheric. Atmospheric or autogenous pressures are usually preferred.
  • the metal leaching processes of the invention may be carried out without the use of any cyanide, it offers significant advantages from the standpoint of both safety and environmental protection. This translates into major cost advantages, since elaborate cyanide disposal facilities and procedures may be entirely eliminated.
  • the extraction or leaching operation will be conducted using a contact time long enough to ensure that at least most of the extractable metal has been leached into the leaching solution.
  • time is not a critical parameter - any suitable contact time may be used.
  • N-halosulfamates attack the precious metal source materials to extract the metal therefrom at rates which may be substantially enhanced in comparison to those achieved in cyanide extraction processes.
  • contact with a leaching solution of this invention may typically provide substantial leaching of ores which require a greater number of hours for leaching with cyanide solutions.
  • the leaching processes of this invention enable recovery of the precious metals from refractory ores and ores containing sulfide minerals and carbonaceous material.
  • the processes are deemed capable of providing improved rates of leaching such ores as compared to cyanide-based processing. While oxidative treatment of sulfide-containing or carbonaceous ores generally remains necessary, the oxidizing power of the leaching agents used pursuant to this invention is such that it may be used for this purpose as well.
  • an acidic solution of the leaching agent is used for both oxidative pre-leaching and leaching of the precious metal from such ores, while either an acidic or basic solution of the leaching agent is used for recovery of the metal from the ore after oxidation and removal of sulfides and excess carbonaceous material.
  • the process technology of this invention makes possible the recovery of metal values from gold ores and other precious metal ores. Moreover, leaching using the leaching solutions of this invention is effective and advantageous for secondary recovery of precious metals from other source materials such as jewelry scraps, spent colloidal gold suspensions, gold plating from electronic circuit boards, spent platinum metal catalysts and the like.
  • the solvated N-halosulfamate source together with one or more solvated alkali metal halides and/or one or more alkaline earth metal halides may be utilized for leaching of the various base metals, particularly those which form halide complex anions such as aluminum, magnesium, chromium, iron, cobalt, nickel, copper, tin, bismuth, antimony, cadmium, lead, zinc, indium, gallium and arsenic.
  • Precious metals of particular interest in the practice of this invention include gold, palladium, silver, rhodium, platinum, osmium, iridium, and the like. Some of these metals may be co-extracted in very small amounts along with other more highly recoverable precious metals. Such other metals may remain as precipitates or in slurry form after recovery of the dissolved forms (e.g., complexes, etc.) of, for example, gold, palladium, silver, and/or rhodium. In short, the processes of this invention have the potential of concentrating these other precious metals in solid form so that they may be recovered and isolated by other processing procedures.
  • the solvated N-halosulfamate source(s) used may react with the with at least one precious metal in the source material to form an anion comprising the precious metal complexed with halogen, and that this complex anion has sufficient stability to remain in the leaching solution.
  • the processes of this invention provide effective methods for recovery of the precious metal(s) while optionally enabling recovery of at least one base metal as well, because of its separation or ready separability from the precious metal complex or other chemical entity form.
  • another embodiment of this invention is a process which comprises preforming or generating in situ at least one N-halosulfamate by chemically or by electrolytically oxidizing at least one halide source in presence of at least one sulfamate source such as sulfamic acid or a water soluble salt of sulfamic acid.
  • the source of sulfamate can be a previously used lixiviant solution whereby the residual active lixiviant is regenerated either chemically or electrolytically.
  • Some of the chemical oxidants for use in forming and/or regenerating N-halosulfamate include Oxone (potassium peroxymonosulfate), bleach (sodium hypochlorite), chlorine and Trichlor (trichloroisocyanuric acid).
  • Oxone potassium peroxymonosulfate
  • bleach sodium hypochlorite
  • chlorine and Trichlor (trichloroisocyanuric acid).
  • Trichlor trichloroisocyanuric acid
  • an advantageous feature of this invention is that concentrated aqueous solutions developed and produced commercially for uses not related to the present invention (e.g., biocidal uses) are available commercially in the form of concentrated aqueous solutions. Simple operations can readily convert most of such solutions into solutions adapted, and highly effective, for use pursuant to this invention.
  • Stabrom ® 909 biocide is a clear yellow to clear orange liquid having a total halogen content expressed as Br 2 of 14.5-15.9 wt , a pH of 12.4-14.0, and a specific gravity at 20°C/20°C of 1.295-1.370. It has a freezing point of approximately 0°C and a boiling point of approximately 106°C, and has complete solubility in water.
  • Stabrom ® Plus biocide is a clear yellow to clear orange liquid having a total halogen content expressed as Br 2 of 17.3-19.1 wt , a pH of 12.4-14.0, and a density of 1.35-1.45 g/mL at 25°C. It has a freezing point of approximately 2°C, a boiling point of approximately 106°C, and is completely soluble in water.
  • Maxxis ® biocide is a clear yellow to clear orange liquid having a total halogen content expressed as Br 2 of 19.7-21.7 wt , a pH of 12.4-14.0, and a density of 1.4-1.55 g/mL at 25°C. It has a freezing point of approximately 7°C (as a summer formulation), and -1°C (as a winter formulation), a boiling point of approximately of 106°C, and is completely soluble in water.
  • the pH levels given above for the Albemarle Corporation products result from use of at least one suitable base of the manufacture of the product.
  • bases are typically alkali metal hydroxides, although other bases can be used, non-limiting examples of which include alkali metal oxides, alkali metal carbonates, alkali metal bicarbonates, or their alkaline earth counterparts, and the like.
  • the components in the above commercial Albemarle Corporation products include a number of other components due to reaction in water among the ingredients used in producing the products.
  • NaOH is present in Stabrom ® 909 biocide and Stabrom ® Plus biocide
  • NaOH and KOH are present in the Maxxis ® biocide formulations.
  • a suitable amount of an acid such as H 2 SO 4 , HC1 or HBr or the like, can be used to reduce the pH of the concentrated solution or preferably the pH of the more dilute aqueous solution for use in the leaching solution just prior to its use in a leaching operation.
  • the base is used as a pre-formed water solution for addition to the concentrated solution as received from Albemarle Corporation. This ensures that the storage life of the remaining concentrated solution will remain high.
  • composition of the BromMax biocides as specified by the supplier in its Material Safety Data Sheet are as follows:
  • the pH of the aqueous leaching solutions used in the practice of this invention can be readily adjusted if necessary to achieve optimum extraction or leaching conditions to the particular precious metal source being treated.
  • mineral acids e.g. , sulfuric acid, hydrobromic acid, hydrochloric acid, nitric acid, phosphoric acid, or the like with H2SO4, HBr, and HC1 being preferred
  • H2SO4, HBr, and HC1 being preferred
  • the acid can be added to the precious metal source, (2) the precious metal source can be added to the acid, or (3) both the acid and the precious metal source can be fed concurrently into the extraction vessel.
  • Precious metal sources which have extraction characteristics similar to gold can be effectively extracted or leached at pH levels in the range of about 7.5 + 0.5 or less, e.g., in the range of above about 1 to about 8, typically in the range of about 2 to about 7.5 + 0.5. In some cases pH levels in the range of about 4 to about 7 or about 4 to about 8 are more preferred. Continuous addition of such acids during the extraction or leaching operation is usually preferred. In any given situation, a few simple pilot tests with a given proposed aqueous leaching solution, a given precious metal source, and a selected acid to achieve optimum extraction at a given temperature will suffice.
  • the treating solution be acidic.
  • the acidic solution should contain at least about 0.05%, preferably at least about 0.1% by weight of the leaching agent.
  • the pH is preferably in the range of about 1 to about 7. Acids which may be used in the acidic leaching solution include hydrochloric acid, hydrobromic acid, phosphoric acid, nitric acid, sulfuric acid, and like mineral acids.
  • the metal source material may be contacted with the leaching solution in any conventional fashion, for example, by causing the leaching solution to percolate through a mass of ore or other sources material.
  • the ore is initially crushed, typically to a particle size of less than 25 millimeters, and the particulate mass is placed on impermeable surfaces such as liners, sheeting or pads prior to initiating perculation of the leaching solution through the crushed source material.
  • the ore may be subjected to vat leaching or agitation leaching.
  • vat leaching the ore is crushed, again typically to a particle size of less than 25 mm, and agglomerated, for example, with lime or cement.
  • Leaching solution is passed through a bed of particulate ore contained within a leaching vessel. The solution may be passed either upwardly or downwardly through the bed of material; or the leaching solution and ore can be moved countercurrently through a continuous or cascade leaching system.
  • the ore In agitation leaching, the ore is typically ground to a finer particle size, for example, to a size in which 50% by weight or more passes through a standard 200 mesh sieve. Thereafter, a leaching slurry is formed by suspending a source material in the leaching solution. Leaching rates are enhanced by agitating the leaching slurry to promote mass transfer from the solid source material to the leaching solution. However, while agitation is desirable, excessive shearing action is undesirable. Therefore, typically a propeller type agitator is used.
  • leaching of ore the ore is contacted with leaching solution in relative proportions equivalent to at least about 2 preferably at least about 5 pounds of N- halosulfamate source per ton of ore.
  • the solids content of the leaching slurry should not be greater than about 40% by weight.
  • Leaching may be carried out at any temperature above ambient, but is preferably conducted at a temperature of between about 70° and about 140° F., i.e., between about 20° and about 60°C. At temperatures in the aforesaid range, leaching proceeds very rapidly. In slurry leaching, complete and quantitative recovery of the precious metal from ore may be accomplished within a contact time of one to two hours, or even less.
  • the conditions employed are generally comparable to those used for leaching.
  • the pre-leaching oxidative treatment step is not normally necessary.
  • the leachate may be subjected directly to electro winning or precipitation.
  • the metal to be recovered is preferably recovered on a cathode of the same metal.
  • an inert cathode may be used.
  • Conventional inert anode materials, current densities, temperatures and other conditions conventionally appropriate for the particular metal to be recovered are utilized in the electrowinning process.
  • the electrolytic system comprises a steel wool cathode and an ion exchange membrane for dividing the anodic and cathodic zones.
  • the leachate contains a precious metal
  • precipitation may be carried out by methods known to the art, for example, in a Merrill- Crowe apparatus using zinc as the precipitating agent.
  • the leachate is contacted with zinc shavings or zinc powder in the presence of lead acetate, the lead acetate typically being provided as a coating on the surface of the zinc.
  • the leachate may be contacted with an ion exchange resin effective for separating anionic precious metal complexes from aqueous solutions. Typical of these are the 3200 to 4200 series of resins selective for silver and gold as sold by Rohm & Haas. The metal may then be recovered from the resin pyrolytically.
  • the leachate is derived from ore, particularly where it is obtained by leaching of refractory or other low grade ore, it is normally desirable to concentrate the metal before attempting to recover it in metallic form.
  • a preferred method for concentrating the metal is by adsorption of halometal complex salts from the leachate onto activated carbon, followed by redissolution in a desorptive leaching solution.
  • the desorbing agent contained in the desorption solution may comprise a solvated N-halosulfamate or cyanide, and the metal may ultimately be recovered from the desorbate by precipitation or electrowinning.
  • Conventional cyanide desorption solutions comprise alkaline mixtures of alcohol, typically ethanol and water.
  • the concentrated desorption solution is preferably substantially saturated with respect to solvated N-halosulfamate, and the desorbate contains 5 to 30 grams per liter of the desorbed metal. It is also preferred that the desorption solution be either alkaline in a pH range of about 7.5 to about 9.5, or acid in a pH range of between about 1 and about 5. Desorptive leaching of the metal from the activated carbon is preferably carried out at a temperature of between about 30°C and about 95°C at atmospheric pressure.
  • a desirable way of recovering precious metal(s) from the aqueous leaching (extraction) solution is to contact this solution with a suitable adsorption agent such as activated carbon or an adsorbent resin.
  • a suitable adsorption agent such as activated carbon or an adsorbent resin.
  • suitable adsorbent resins are Dowex- 21k resin and Reilex 425 ion exchange resin.
  • the contacting may be effected in various ways such as stirring the adsorption agent in a body of the aqueous leaching solution and recovering the resultant metal-containing particles by a mechanical separation procedure such as filtration, centrifugation, decantation, or the like.
  • the aqueous leaching solution can be passed through a bed of the adsorption agent whereby a bed of particles of adsorbed precious metal-containing product is formed for further treatment such as incinerating or smelting the carbon or resin particles to recover the precious metal(s).
  • the precious metal may be recovered from the adsorptive resins by extraction of the precious metal-laden particles by contacting the adsorbent with an eluting solution containing an eluant such as hydrochloric acid or acidified thiourea.
  • an eluant such as hydrochloric acid or acidified thiourea.
  • Other methods known to the art e.g., pyrolysis, may also be used for these recovery operations.
  • Electrowinning of the precious metal or base metal from a solvated N- halosulfamate solution comprises a useful method for recovery of such metals.
  • the electrolytic solution used for electrowinning contains between about 5 and about 30 grams per liter, preferably at least about 15 grams per liter, of the desired metal in the form of halometal complex anions, and is substantially saturated with respect to solvated N- halosulfamate.
  • the electrowinning solution is acidic, it preferably has a pH of between about 4 and about 6. Where it is alkaline, it preferably has a pH of between about 7.5 and about 9.
  • electrolytic solutions of the type described above in connection with electrowinning can be used for other electrodeposition processes, including electrorefining and electroplating.
  • the anode comprises the metal to be purified, and the electrolytic solution contains solvated N- halosulfamate and halogen complex anions of the metal which is to be deposited at the cathode as direct current is applied.
  • the metal to be refined is deposited at the cathode, while in other instances an impurity is deposited at the cathode while the metal to be refined is collected in the form of a sludge or mud as the anode disintegrates.
  • gold contaminated with silver may be refined by subjecting an anode of such material to electrolysis in a bath comprising solvated N-halosulfamate and halogenated silver complex anions.
  • Silver is deposited at the cathode and as the anode disintegrates a mud rich in gold is collected by conventional means, for example, in a filter bag surrounding the anode.
  • the mud is washed and the gold contained therein is melted down, formed into another anode, and subjected to further electrofining, this time in a bath comprising solvated N-halosulfamate and halogenated gold complex anions, with metallic gold being deposited at the cathode.
  • a part to be plated is immersed in a bath comprising a solvated N-halosulfamate and halogen complex anions of the metal to be deposited.
  • the anode may be either inert or comprise the plating metal.
  • electrofining and electroplating as in electrowinning, the temperatures, current densities, voltages, electrode spacings, etc., are those conventionally used in the art.
  • a 5-L reactor fitted with a condenser, an addition funnel, a mechanical stirrer and a thermometer was charged with 1650 g of deionized water and agitated at 150 rpm.
  • Sulfamic acid (440 g; 4.54 moles) was added in small portions and dissolved in water.
  • a solution of 50% NaOH (947g; 11.84 moles) was taken in the addition funnel and added dropwise, keeping the temperature of the mixture below 50°C. After the addition, the mixture was allowed to cool to room temperature.
  • the addition funnel was replaced with a Teflon feeding tube connected to a peristaltic pump. The agitation of the mixture was increased to 200 rpm.
  • Example 1 bromine (529 g; 3.31 moles) was fed to the reactor at a rate of 2mL/minute. Temperature of the mixture was 25-30oC during the addition. The mixture was stirred for an additional 30 minutes after the addition and the clear yellow product solution (3625 g) was then transferred to amber plastic bottles for storage. Analysis of the solution showed a pH of 12.2 and "active" bromine concentration of 14.7 wt%.
  • the chemical reactions involved in Example 1 are as follows:
  • a 5 g sample of the gold ore (DS-1 from Natural Resources Canada, containing 32.6 ppm of Au and 2.85 wt% S) was suspended in 20 g of water and magnetically stirred at room temperature.
  • Stabrom 909 and sulfuric acid were continually added over a period of 6 hours while maintaining the pH of the mixture below 7 and ORP above 800mV.
  • the mixture which has consumed 21.5 g of Stabrom 909 and about 8.5 g of sulfuric acid was then stirred overnight at room temperature. It was then filtered and the filtrate was analyzed by ICP. The analysis showed it had 3.0 ppm of Au indicating about 92% recovery of gold from the ore.
  • a leaching solution (lixiviant solution) was used in a leaching operation for recovery of gold pursuant to this invention.
  • the leaching agent used in that operation was produced as in Example 1.
  • the resultant used leaching agent solution was colorless with an ORP of 520 mV.
  • To a lOg sample of that used solution was added about 100 mg of a 5% solution of sodium hypochlorite (bleach) and the resultant mixture was stirred. The solution immediately turned yellow and the ORP of the solution was found to have been increased to 840 mV.
  • a leaching solution (lixiviant solution) was used in a leaching operation for recovery of gold pursuant to this invention.
  • the leaching agent used in that operation was produced as in Example 1.
  • the resultant used leaching agent solution was colorless with an ORP of 520 mV.
  • To a lOg sample of that used solution was added about 100 mg of trichloroisocyanuric acid (Trichlor) and the resultant mixture was stirred. The solution immediately turned yellow and the ORP of the solution was found to have been increased to 840 mV.
  • a leaching solution (lixiviant solution) was used in a leaching operation for recovery of gold pursuant to this invention.
  • the leaching agent used in that operation was produced as in Example 1.
  • the resultant used leaching agent solution was colorless with an ORP of 520 mV.
  • To a lOg sample of that used solution was added about 100 mg of potassium peroxymonosulfate (Oxone) and the resultant mixture was stirred. The solution immediately turned yellow and the ORP of the solution was found to have been increased to 840 mV.
  • Example 8 illustrates the effect of preferred mildly acidic to mildly basic pH levels on the performance of an aqueous leaching solution containing at least solvated N-bromosulfamate and solvated N-chlorosulfamate together with solvated alkali metal halide(s) in dissolving, leaching or extracting gold from a source material on contact between such solution and the gold in such source material pursuant to this invention.
  • concentrated forms of such solutions available commercially as Stabrom ® 909 biocide, Stabrom ® Plus biocide, and Maxxis ® biocide, have pH levels in the range of 12.4-14.0.
  • a piece of gold wire (0.25 mm diameter; 6.2 mg weight) was dropped into a solution containing 50 ml of Stabrom 909 solution diluted with 50 ml of deionized water.
  • the alkaline solution with the gold wire was stirred magnetically for 50 hours at room temperature. The gold wire did not dissolve.
  • a sample of the solution was taken out for ICP analysis.
  • the solution was then acidified by dropwise addition of 48% hydrobromic acid to a pH of 5 and stirred with the gold wire for 15 hours. The gold wire completely dissolved in the solution.
  • a sample of the solution was analyzed by ICP. The ICP analysis of the sample before acidification indicated that ⁇ 0.6 ppm of Au had dissolved.
  • the pH is adjusted, preferably within a reasonably short period before use to a level of about 8 or below and preferably about 4 to about 8 and more preferably in the range of 4 to 7 and still more preferably in the range of 4 to 6.
  • Example 9 demonstrates the efficacy of this invention in recovery of palladium in very high yields under suitable conditions. In fact, in this experimental work a 100% recovery was achieved.
  • Stabilized Bromine solution (10 mL) prepared in Example 1 was mixed with 1 gram of NaBr and diluted with 90 mL of water and pH of the solution was adjusted to 4 by adding a few drops of 48% hydrobromic acid. A piece of palladium wire (0.5 mm diameter; 99.9% purity) weighing 14 mg was dropped into this solution and magnetically stirred at room temperature. After stirring for 24 hours, a sample of the solution was analyzed by ICP. The analysis showed the solution had 93.5 ppm (67% recovery) of palladium. Stirring of the mixture was continued to 60 hours. A sample of the solution after 60 hours of stirring showed 141 ppm (100% recovery) of palladium. EXAMPLE 10
  • the mixture was acidified to a pH of ⁇ 1 by adding 10 grams of 48% hydrobromic acid and stirred for additional 40 hours.
  • a sample of the mixture was filtered through syringe filter and the clear filtrate was analyzed for metals by ICP.
  • the solution was found to contain 272 ppm of silver (96% recovery), 253 ppm of palladium (95% recovery) and 33 ppm of rhodium (20% recovery).
  • A) forming or obtaining a composition comprising (i) an aqueous medium containing in the range of about 1 to about 100 grams/liter (preferably in the range of about 1 to about 10 grams/liter for gold and/or palladium and in the range of about 50 to about 75 grams/liter for silver and/or rhodium) of at least one solvated N- bromosulfamate compound and (ii) in the range of about 1 to about 100 grams/liter (preferably in the range of about 1 to about 20 grams/liter) of solvated sodium bromide and in the range of about 5 to about 400 grams/liter (preferably in the range of about 10 to about 200 grams/liter) of solvated sodium hydroxide;
  • a lixiviant solution having a pH in the range of about 7.5 + 0.5 or less (preferably a pH in the range of about 4 to about 6 for gold and/or palladium, and preferably a pH in the range of about 1 or less for silver and/or rhodium), and optionally diluting said lixiviant solution with water to provide a diluted solution having a reduced active bromine content sufficient to leach gold, palladium, silver, and/or rhodium from a leachable source; and
  • Another such embodiment is a composition comprising gold, palladium, silver, and/or rhodium in the form of a solute in an aqueous medium comprising (A) water, (B) at least one solvated N-bromosulfamate source, and (CI) solvated sodium bromide or (C2) solvated ammonium bromide or (C3) solvated alkaline earth metal bromide, or (C4) a combination of any two or all three of (CI), (C2), (C3), the solution having a pH in the range of about 7.5 + 0.5 or less.
  • the bench scale leaching set-up consisted of a 1000 mL baffled reactor and an overhead stirrer with a flat-bladed impeller. At the start of each test, 5 g of mineral was added to 250 mL of 10 g/L NaBr solution and placed in the reactor. The stirring speed was maintained at 375 RPM. The rate of addition of stabilized bromine was generally synchronized with the redox controlled pumping system. The rate of oxidation of sulphide was estimated by analysing the kinetic solution samples for their sulphate content.
  • the gold analyses were performed using the fire assay method and the bromide content was quantitatively determined by Ion Chromatography.
  • the copper, iron and arsenic concentrations were determined X-ray Fluorescence analysis.
  • the sulphides were determined by Leco analysis.
  • the concentration of bromine was estimated by titrating against thiosulphate in the presence of starch indicator.
  • the leaching agent used in this program was a concentrated aqueous solution containing 11-15 wt active bromine and comprising solvated N-bromosulfamate, solvated sodium bromide, and solvated sodium hydroxide.
  • the concentrated solution has a pH in the range of about 11 to about 13, and was diluted in water to the desired active bromine concentrations used in the testing operations.
  • the leaching agent is often referred to as stabilized bromine or as a "bromine/bromide lixiviant".
  • the leaching solutions of this invention have an oxidation potential of >600 mV, more preferably >750 mV; and/or preferably an "active" halogen concentration of 0.5 g/L to 75 g/L, more preferably, 1 g/L to 10 g/L; and/or preferably a halide to "active" halogen ratio of 100/1 to 1/5, more preferably 10/1 to 1/1.
  • the solution in the iodine flask is titrated with the 0.1 normal sodium thiosulfate; when a faint yellow color is observed, one milliliter of a 1 wt % starch solution in water is added, changing the color of the solution in the flask from faint yellow to blue. Titration with sodium thiosulfate continues until the blue color disappears.
  • the amount of active bromine is calculated using the weight of the sample and the volume of sodium thiosulfate solution titrated.
  • the amount of active bromine in a composition of this invention regardless of actual chemical form, can be quantitatively determined. Such a method is described for example in Chapter XIV of Willard-Furman, Elementary Quantitative Analysis, Third Edition, D. Van Nostrand Company, Inc., New York, Copyright 1933, 1935, 1940.
  • Another method of determining active bromine especially at relatively low concentrations is the so-called DPD Method which uses N,N'-diethyl-p-phenylenediamine as the indicator in this titration method in which KI and a buffer are also used. This method is described inhack Water Analysis Handbook, 3rd edition, copyright 1997. Although the method refers primarily to determination of "free chlorine” and “total chlorine” values i.e., “active chlorine” values, it can also be used for determination for active bromine values. To convert “free chlorine” and “total chlorine” values into “free bromine” and “total bromine” i.e., “active bromine” values, the respective value for "free chlorine” or “total chlorine” is multiplied by 2.25.
  • the rate of gold dissolution was estimated at various Stabilized Bromine dosages and active bromine concentrations between 0.65 g/L and 38.4 g/L.
  • the sodium bromide was added at a concentration of 9 to 10 g/L except for one test, where the addition of large volumes of acid, necessary to reach the target pH 4, diluted the sodium bromide concentration to ⁇ 5 g/L.
  • Table 1 Varying Bromine Concentrations in Rotating Disk Gold Leaching Tests
  • Rates of gold dissolution in cyanide and stabilized bromine are compared in Figure 3.
  • the dissolution rate in cyanide was 3.03 mg/cm 2 /h which is in the same range as rate of gold dissolution achieved with Stabilized Bromine.
  • gold dissolution rates with cyanide are limited by the low solubility of oxygen in aqueous solution
  • the rate of gold leaching with bromine can be increased by increasing the concentration of active bromine in solution, as illustrated in Figure 3 (concentration of 12.9 g/L Stabilized Bromine).
  • thermodynamics of this system dictate that the stability region for gold bromide extends from acid to neutral pH at potentials between -0.9-1.5 V vs. SHE, as depicted in Figure 4.
  • This En-pH diagram was constructed for gold and bromide concentrations of 10 "4 M and 10 "1 M, respectively. At lower gold concentrations, the stability region of gold bromide shifts towards more acidic region (not shown here).
  • the product of bromine reduction is the bromide ion.
  • Table 1 and Table 2 show the final bromide concentration is higher than the concentration of bromide added as the sodium salt at the start of the tests. If the difference is plotted against the amount of bromine consumed in the test, the production of bromide from added bromine may be correlated. This relationship has been plotted in Figure 5. Based on this approach, it appears that about 1.7 mol of bromide was produced from every mol of bromine added as Stabilized Bromine, which is slightly less than the theoretical ratio of 2. The balance presumably represents bromine that was lost as unreacted vapour.
  • Figure 10 maps the molar ratio of aqueous iron produced in solution versus bromine consumption, which should be 7.5 based on the equation above. All points lie above the theoretical line. This suggests that some of the leached iron oxidized to ferric, hydrolyzed and re-precipitated during the test. This is supported by the observation that the data points furthest from the theoretical line belong to the test (1.0 V) that was run at pH 2.5-2.2. The data points for the second test (1.10 V), which was conducted at pH 1.9-2.1 were situated closer to the line.
  • oxidized copper/gold ores reacts readily with cyanide and consumes about 4 mole of cyanide for every mole of copper leached ( ⁇ 3 kg NaCN per kg Cu). This can render the processing of such ores with cyanide uneconomic.
  • the copper in oxidized copper/gold ores is fairly inert in a bromine/bromide leaching medium, and there is a possibility that this process will enjoy lower reagent consumption than cyanide.
  • the stabilized bromine lixiviant of this invention is especially effective when applied to extraction of gold from cyanide-robbing ores, such as copper containing ores. Additional tests involving use of oxidized copper-containing gold ore further demonstrated such highly desirable performance. These gold extraction tests and the results therefrom are summarized in Table 11 and are presented in Figs. 17 and 18.
  • the use of one or more solvated N-halosulfamate sources and at least one solvated alkali metal halide, at least one solvated ammonium halide or at least one solvated alkaline earth metal halide, or a combination of any two or all three of these as the lixiviant preferably involves utilization of additional operations in an overall integrated process for the recovery of gold.
  • a preferred overall integrated process of this invention is depicted in Figure 21. As shown, there are four operations labeled as "Leaching Process”, “Gold Recovery”, “Conversion by Electrolysis”, and Leachant Makeup”.
  • the "Leaching Process” represents the processes and resultant compositions formed in the leaching processes.
  • the “Gold Recovery” represents adsorption and elution operations referred to and described herein such as carbon in pulp (CIP), or carbon in leach (CIL), or resin in pulp (RIP), or resin in leach (RIL).
  • CIP carbon in pulp
  • CIL carbon in leach
  • RIP resin in pulp
  • RIL resin in leach
  • the “Conversion by Electrolysis” represents the electrolytic regeneration of the bromine lixiviant for reuse.
  • the “Leachant Makeup” represents the reuse of bromine lixiviant as well as use of additional makeup lixiviant. Accordingly, the integrated process as a whole is as set forth in the foregoing specification, appended claims and Figures.
  • the aqueous leaching solutions of this invention may be used in combination with other known precious metal lixivants such as, for example, 1,3-dibromo- 5,5-dialkylhydantoins (e.g. , l,3-dibromo-5,5-dimethylhydantoin) and/or ⁇ , ⁇ '- bromochloro-5,5-dialkylhydantoins (e.g. , N,N'-bromochloro-5,5-dimethylhydantoin).
  • 1,3-dibromo- 5,5-dialkylhydantoins e.g. , l,3-dibromo-5,5-dimethylhydantoin
  • ⁇ , ⁇ '- bromochloro-5,5-dialkylhydantoins e.g. , N,N'-bromochloro-5,5-dimethylhydantoin
  • the term "about" modifying the quantity of an ingredient in the compositions of the invention or employed in the methods of the invention refers to variation in the numerical quantity that can occur, for example, through typical measuring and liquid handling procedures used for making concentrates or use solutions in the real world; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods; and the like.
  • the term “about” also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial mixture. Whether or not modified by the term "about”, the claims include equivalents to the quantities.
  • the invention may comprise, consist, or consist essentially of the materials and/or procedures recited herein.

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  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
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  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

L'invention porte sur de nouveaux procédés utiles pour la lixiviation de métaux précieux de sources composées de ces métaux ou les contenant. Les agents de lixiviation utilisés sont des solutions aqueuses de métal alcalin, de métal alcalino-terreux, d'ammonium et/ou de N-halosulfamate(s) solvaté, et d'un ou de plusieurs halogénures de métal alcalin ou halogénures de métal alcalino-terreux ou halogénures d'ammonium. L'invention porte également sur des compositions constituées de ces solutions aqueuses contenant au moins un métal précieux sous la forme d'un soluté.
PCT/US2014/070325 2013-12-30 2014-12-15 Procédé de dissolution ou d'extraction d'au moins un métal précieux d'une matière source le contenant WO2015102865A1 (fr)

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CN111100986A (zh) * 2020-02-25 2020-05-05 东南大学 一种高效选择性浸出金的非氰浸金剂及制备方法和用途
WO2020198778A1 (fr) 2019-04-03 2020-10-08 Clean Earth Technology Pty Ltd Matériaux et procédés de récupération de métaux précieux
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US11814698B2 (en) 2015-04-21 2023-11-14 Excir Works Corp. Methods for simultaneous leaching and extraction of precious metals
US11427886B2 (en) 2015-04-21 2022-08-30 Excir Works Corp. Methods for simultaneous leaching and extraction of precious metals
US11408053B2 (en) 2015-04-21 2022-08-09 Excir Works Corp. Methods for selective leaching and extraction of precious metals in organic solvents
CN111919326A (zh) * 2018-03-27 2020-11-10 大金工业株式会社 电解液、电化学器件、锂离子二次电池、组件以及化合物
KR20200134295A (ko) * 2018-03-27 2020-12-01 다이킨 고교 가부시키가이샤 전해액, 전기 화학 디바이스, 리튬 이온 이차 전지, 모듈 및 화합물
JPWO2019188207A1 (ja) * 2018-03-27 2021-01-14 ダイキン工業株式会社 電解液、電気化学デバイス、リチウムイオン二次電池、モジュール及び化合物
US20210028492A1 (en) * 2018-03-27 2021-01-28 Daikin Industries, Ltd. Electrolyte solution, electrochemical device, lithium ion secondary battery, module and compound
US20210043974A1 (en) * 2018-03-27 2021-02-11 Daikin Industries, Ltd. Electrolyte solution, electrochemical device, lithium ion secondary battery, and module
US11916195B2 (en) 2018-03-27 2024-02-27 Daikin Industries, Ltd. Electrolyte solution, electrochemical device, lithium ion secondary battery, and module
CN111919326B (zh) * 2018-03-27 2024-06-11 大金工业株式会社 电解液、电化学器件、锂离子二次电池、组件以及化合物
US12107225B2 (en) * 2018-03-27 2024-10-01 Daikin Industries, Ltd. Electrolyte solution, electrochemical device, lithium ion secondary battery, module and compound
JP7164821B2 (ja) 2018-03-27 2022-11-02 ダイキン工業株式会社 電解液、電気化学デバイス、リチウムイオン二次電池、モジュール及び化合物
KR102533995B1 (ko) * 2018-03-27 2023-05-19 다이킨 고교 가부시키가이샤 전해액, 전기 화학 디바이스, 리튬 이온 이차 전지, 모듈 및 화합물
WO2020077028A1 (fr) * 2018-10-12 2020-04-16 Basf Se Auxiliaires de lixiviation et procédés d'utilisation d'auxiliaires de lixiviation
EP3947760A4 (fr) * 2019-04-03 2022-12-07 Clean Earth Technology Pty Ltd Matériaux et procédés de récupération de métaux précieux
WO2020198778A1 (fr) 2019-04-03 2020-10-08 Clean Earth Technology Pty Ltd Matériaux et procédés de récupération de métaux précieux
CN111100986B (zh) * 2020-02-25 2022-04-26 东南大学 一种高效选择性浸出金的非氰浸金剂及制备方法和用途
CN111100986A (zh) * 2020-02-25 2020-05-05 东南大学 一种高效选择性浸出金的非氰浸金剂及制备方法和用途

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