EP3110982A1 - Wet based formulations for the selective removal of noble metals - Google Patents

Wet based formulations for the selective removal of noble metals

Info

Publication number
EP3110982A1
EP3110982A1 EP15755407.2A EP15755407A EP3110982A1 EP 3110982 A1 EP3110982 A1 EP 3110982A1 EP 15755407 A EP15755407 A EP 15755407A EP 3110982 A1 EP3110982 A1 EP 3110982A1
Authority
EP
European Patent Office
Prior art keywords
acid
leaching composition
noble metals
chloride
composition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP15755407.2A
Other languages
German (de)
French (fr)
Other versions
EP3110982A4 (en
Inventor
Tianniu Chen
Ping Jiang
Michael B. Korzenski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Entegris Inc
Original Assignee
Entegris Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Entegris Inc filed Critical Entegris Inc
Publication of EP3110982A1 publication Critical patent/EP3110982A1/en
Publication of EP3110982A4 publication Critical patent/EP3110982A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
    • C25C1/20—Electrolytic production, recovery or refining of metals by electrolysis of solutions of noble metals
    • 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
    • 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
    • C22B11/042—Recovery of noble metals from waste materials
    • 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
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
    • C22B3/065—Nitric acids or salts thereof
    • 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
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
    • C22B3/08—Sulfuric acid, other sulfurated acids or salts thereof
    • 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
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/22—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition
    • 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
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/10—Etching compositions
    • C23F1/14—Aqueous compositions
    • C23F1/16—Acidic compositions
    • C23F1/30—Acidic compositions for etching other metallic material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates generally to processes for recycling/reclaiming of noble metals, such as ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold from source materials.
  • noble metals such as ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold from source materials.
  • noble metals such as gold, silver and platinum group metals which offer the opportunity for economical recovery.
  • gold is available from ores and numerous scrap sources, including industrial wastes, gold plated electronic circuit boards, and in alloys with copper, zinc, silver or tin in the karat gold used in jewelry.
  • Silver is available from photographic and x-ray film emulsions, scrap sterling, and numerous industrial sources.
  • Platinum group metals are available from industrial sources, such as catalysts. There are numerous instances in which it is desirable to recover these metals from an aggregate material.
  • Platinum is a silvery, white, ductile metal which is insoluble in mineral and organic acids, but soluble in aqua regia. Platinum does not corrode or tarnish, and forms strong complexes with halides (i.e., chloride, bromide, fluoride and iodide). Platinum is used as a catalyst (nitric acid, sulfuric acid, and high-octane gasoline production; automobile exhaust gas converters), in laboratory ware, spinnerets for rayon and glass fiber manufacture, jewelry, dentistry, electrical contacts, thermocouples, surgical wire, bushings, electroplating, electric furnace windings, chemical reaction vessels, anti-cancer drugs and permanent magnets.
  • halides i.e., chloride, bromide, fluoride and iodide
  • Platinum is used as a catalyst (nitric acid, sulfuric acid, and high-octane gasoline production; automobile exhaust gas converters), in laboratory ware, spinnerets for rayon and glass fiber manufacture, jewelry, dentistry,
  • Palladium is similarly a silvery, white, ductile metal which does not tarnish in air. It is the least noble (e.g., most reactive) of the platinum group, is insoluble in organic acids, but soluble in aqua regia and fused alkalies. Palladium is used as a catalyst for chemical processes including reforming cracked petroleum fractions and hydrogenation, for metallizing ceramics, as "white gold” in jewelry, in protective coatings, and in hydrogen valves (in hydrogen separation equipment). . Both platinum and palladium are good electrical conductors and are used in alloys for electrical relays in switching systems and telecommunication equipment, resistance wires and aircraft spark plugs. Further, platinum group metal applications include industrial radiography, catalysts, pen points, electrical contacts, jewelry, coatings and headlight reflectors.
  • the present invention relates generally to compositions and processes for leaching noble metals from sources comprising same including, but not limited to, ores, jewelry, scraps comprising said noble metals, waste materials, alloys, catalyst materials, and various industrial sources. More specifically, the compositions for leaching noble metals from sources are acidic, halide-based compositions that efficiently remove noble metals from the source at room temperature.
  • a leaching composition comprising at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent.
  • a method of removing noble metals from a source comprising contacting said source under conditions with the leaching composition, wherein said noble metals are dissolved or otherwise solubilized in the leaching composition, and wherein the leaching composition comprises at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent.
  • the present invention relates generally to compositions and processes for leaching noble metals from sources comprising same including, but not limited to, ores, jewelry, scraps comprising said noble metals, waste materials, alloys, catalyst materials, and various industrial sources. More specifically, the compositions for leaching noble metals from sources are acidic, halide-based compositions that efficiently remove noble metals from the source at low temperatures.
  • “noble metals” refers to the group of metals including gold, silver, the platinum group metals, alloys comprising same, and combinations thereof.
  • the "platinum group metals” include ruthenium, osmium, rhodium, iridium, palladium and platinum.
  • base metals corresponds to iron, nickel, zinc, copper, aluminum, tungsten, molybdenum, tantalum, magnesium, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium, thallium, alloys comprising same, and combinations thereof.
  • substantially devoid is defined herein as less than 2 wt. %, preferably less than 1 wt. %, more preferably less than 0.5 wt. %, and most preferably less than 0.1 wt. %. "Devoid” corresponds to 0 wt. %.
  • halide corresponds to fluoride, chloride, bromide or iodide -containing species such as salts or acids.
  • the "source” is a noble metal-containing material including, but not limited to, ores, jewelry, scraps comprising said noble metals, waste materials comprising said noble metals including electronic waste, alloys, catalyst materials, various industrial sources, and combinations thereof.
  • to remove noble metals from a source means that the noble metal is substantially dissolved or solubilized or the like in the leaching composition, while base metals are not substantially dissolved or solubilized or the like.
  • substantially dissolved is defined herein more than 95 wt. % of the material originally present is dissolved or solubilized or the like, preferably more than 98 wt. %, more preferably more than 99 wt. %, and most preferably more than 99.9 wt. %.
  • “Not substantially dissolved” is defined herein less than 5 wt. % of the material originally present is dissolved or solubilized or the like, preferably less than 2 wt. %, more preferably less than 1 wt. %, and most preferably less than 0.1 wt. %.
  • the term “leaches” or “leaching” corresponds to the complete or partial removal or extraction of the gold and/or other noble metals from the source into the leaching composition.
  • the gold or other noble metal is dissolved or otherwise solubilized in the leaching composition, preferably dissolved.
  • crushing corresponds to any method that substantially exposes the gold and other noble metals of the source material to the leaching composition, e.g., crushing, cracking, pulverizing, shredding, or grinding.
  • agitation means include, but are not limited to, physical agitation such as mixing, recirculation, turbulence, and combinations thereof.
  • compositions may be embodied in a wide variety of specific formulations, as hereinafter more fully described.
  • specific constituents of the composition are discussed in reference to weight percentage ranges including a zero lower limit, it will be understood that such constituents may be present or absent in various specific embodiments of the composition, and that in instances where such constituents are present, they may be present at concentrations as low as 0.001 weight percent, based on the total weight of the composition in which such constituents are employed.
  • a method of removing noble metals from a source wherein said noble metals are dissolved or otherwise solubilized in a leaching composition. More specifically, the method of removing noble metals from a source comprises contacting said source with a leaching composition, wherein said noble metals are dissolved or otherwise solubilized in the leaching composition. Preferably, noble metals are selectively removed relative to base metals also present in the source.
  • new volumes of the source can be added to the leaching composition and the process of removing the noble metals can be repeated again and again until the leaching composition is saturated with noble metals.
  • a "feed and bleed" process may be used wherein clean leaching composition is periodically introduced to the working leaching composition with simultaneous withdrawal of some of the working leaching composition.
  • the leaching composition comprising the noble metals can be processed to obtain useful forms of said noble metals (e.g., electrochemically, by electrowinning, or using reducing agents).
  • the leaching composition is contacted in any suitable manner to the source, e.g., by spraying the leaching composition on the source, by dipping the source in a volume of the leaching composition, by contacting the source with another material, e.g., a pad, or fibrous sorbent applicator element, that has the leaching composition absorbed thereon, by contacting the source with a recirculating composition, or by any other suitable means, manner or technique, by which the leaching composition is brought into contact with the source.
  • a suitable manner or technique by which the leaching composition is brought into contact with the source.
  • the source i.e., noble metal containing material
  • the leaching composition can be added to the leaching composition as is, pulverized into a powder, shredded into pieces, crushed, or in any other form so long as the metals contained in the source are readily exposed for removal from the source.
  • the leaching composition and the source can be agitated such that the source is substantially exposed to the leaching composition.
  • the leaching composition typically is contacted with the source for a time of from about 1 min to about 120 minutes, preferably about 3 min to 60 at temperature in a range of from about 20°C to about 100°C, preferably in a range from about 20°C to about 60°C, more preferably about 20°C to about 40°C, and most preferably about room temperature.
  • Such contacting times and temperatures are illustrative, and any other suitable time and temperature conditions may be employed that are efficacious to remove the noble metals from the source comprising same.
  • a leaching composition comprising, consisting of, or consisting essentially of at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent.
  • the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one chloride salt, at least one acid, and at least one solvent.
  • the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one chloride salt, at least one sulfur- containing acid, and at least one solvent.
  • the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one alkaline chloride salt, at least one sulfur-containing acid, and at least one solvent.
  • the leaching composition comprises, consists of, or consists essentially of at least one nitrate salt oxidizing agent, at least one alkaline chloride salt, at least one sulfur-containing acid, and at least one solvent.
  • the leaching composition is aqueous in nature and has a pH less than about 2, more preferably less than about 1.
  • the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one halide salt, at least one acid, and at least one solvent, present in the following weight percentages, based on the total weight of the composition:
  • the leaching composition comprises, consists of, or consists essentially of at least one nitrate salt oxidizing agent, at least one alkaline chloride salt, at least one sulfur-containing acid, and at least one solvent, present in the following weight percentages, based on the total weight of the composition:
  • Oxidizing agents are included in the composition to oxidize the metals to be removed into an ionic form and accumulate highly soluble salts of dissolved metals.
  • Oxidizing agents contemplated herein include, but are not limited to, ozone, nitric acid (HN0 3 ), bubbled air, cyclohexylaminosulfonic acid, , hydrogen peroxide (H 2 0 2 ), oxone (potassium peroxymonosulfate, 2KHSO 5 KHSO 4 K 2 SO 4 ), ammonium polyatomic salts (e.g., ammonium peroxomonosulfate, ammonium chlorite (NH 4 C10 2 ), ammonium chlorate (NH 4 CIO 3 ), ammonium iodate (NH 4 IO 3 ), ammonium perborate (NH 4 BO 3 ), ammonium perchlorate (NH 4 CIO 4 ), ammonium periodate (NH 4 IO 3 ), ammonium pers
  • the oxidizing agent comprises a nitrate ion including, but not limited to, nitric acid, sodium nitrate, potassium nitrate, ammonium nitrate, tetraalkylammonium nitrate, and combinations thereof.
  • the at least one halide is preferably a chloride-containing compound including, but not limited to, hydrochloric acid, and alkaline chlorides (e.g., sodium chloride, potassium chloride, rubidium chloride, cesium chloride, magnesium chloride, calcium chloride, strontium chloride, ammonium chloride, quaternary ammonium chloride salts), and combinations thereof, with the proviso that the chloride-containing compound cannot include copper chloride, chlorine gas, or a second, different halide.
  • the at least one halide is devoid of compounds such as CuCl 2 , Cl 2 , and BrCl 2 " .
  • the at least one halide comprises an alkaline chloride, even more preferably an alkali metal chloride such as sodium chloride.
  • the at least one halide can also include salts and/or acids comprising bromide and iodide including, but not limited to, sodium bromide, sodium iodide, potassium bromide, potassium iodide, rubidium bromide, rubidium iodide, cesium bromide, cesium iodide, magnesium bromide, magnesium iodide, calcium bromide, calcium iodide, strontium bromide, strontium iodide, ammonium bromide, ammonium iodide, quaternary ammonium bromide salts, and quaternary ammonium bromide salts.
  • the at least one halide is preferably substantially devoid of fluoride ions.
  • the at least one acid is preferably a sulfur-containing species such as sulfuric acid, sulfate salts (e.g., sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate), sulfonic acid, sulfonic acid derivatives, and combinations thereof.
  • sulfuric acid e.g., sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate
  • sulfate salts e.g., sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, magnesium sulfate, calcium sulfate, strontium sulf
  • Sulfonic acid derivatives contemplated include methanesulfonic acid (MSA), ethanesulfonic acid, 2-hydroxyethanesulfonic acid, n-propanesulfonic acid, isopropanesulfonic acid, isobutenesulfonic acid, n-butanesulfonic acid, n-octanesulfonic acid), benzenesulfonic acid, benzenesulfonic acid derivatives, and combinations thereof.
  • the at least one acid comprises sulfuric acid, preferably concentrated sulfuric acid.
  • the at least one solvent includes, but is not limited to, water, methanol, ethanol, isopropanol, butanol, pentanol, hexanol, 2-ethyl-l-hexanol, heptanol, octanol, ethylene glycol, propylene glycol, butylene glycol, tetrahydrofurfuryl alcohol (THFA), butylene carbonate, ethylene carbonate, propylene carbonate, dipropylene glycol, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol phenyl
  • the leaching composition further comprises a corrosion inhibitor, specifically a base metal corrosion inhibitor, so as to ensure that the leaching composition selectively removes noble metals from the source relative to base metals.
  • the leaching composition can comprise, consist of, or consist essentially of at least one oxidizing agent, at least one halide, at least one acid, at least one solvent, and at least one corrosion inhibitor.
  • the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one chloride salt, at least one acid, at least one solvent, and at least one corrosion inhibitor.
  • the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one chloride salt, at least one sulfur-containing acid, at least one solvent, and at least one corrosion inhibitor.
  • Corrosion inhibitors for passivating the base metals include, but are not limited to, ascorbic acid, adenosine, adenine, L(+)-ascorbic acid, isoascorbic acid, ascorbic acid derivatives, citric acid, ethylenediamine, gallic acid, oxalic acid, tannic acid, ethylenediaminetetraacetic acid (EDTA), uric acid, 1,2,4-triazole (TAZ), triazole derivatives (e.g., benzotriazole (BTA), tolyltriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole, 3-amino-5- mercapto- 1,2,4-triazole, 1 -amino- 1,2,4-
  • the leaching composition of the second aspect can further comprise noble metal chelators, surfactants, defoamers, and combinations thereof, as readily determined by the person skilled in the art.
  • the leaching composition comprises, consists of, or consists essentially of sodium chloride, sulfuric acid, nitric acid, and water, with the proviso that the leaching composition is substantially devoid of hydrogen peroxide, copper (II) chloride, chlorine gas, BrCl 2 ⁇ , fluoride-containing compounds, hydroxide -containing compounds, ferrous ions, a sulfur compound comprising a sulfur atom with an oxidation state in the range of -2 to +5, and cyanides.
  • the leaching composition comprises a nitrate such as nitric acid
  • NO x gases can be emitted.
  • the leaching process is carried out in a system comprising a condenser, wherein the NO x gases can be collected and converted back into nitric acid, as readily known to the person skilled in the art.
  • NO x corresponds to mononitrogen oxides such as NO and N0 2 .
  • the leaching composition is easily recyclable and can be employed in a closed-loop process generating minimal waste.
  • the resulting leaching composition including the noble metals can be recycled by reclaiming the noble metals.
  • the recycled leaching solution can be reused, with or without the addition of fresh leaching composition chemistry.
  • the leaching composition is essentially non-toxic once the noble metals are reclaimed and the excess acidity neutralized.
  • the leaching compositions described herein are easily formulated by simple addition of the respective ingredients and mixing to homogeneous condition. Furthermore, the leaching composition may be readily formulated as single-package formulations or multi-part formulations that are mixed at or before the point of use, e.g., the individual parts of the multi-part formulation may be mixed at the tool or in a storage tank upstream of the tool.
  • the concentrations of the respective ingredients may be widely varied in specific multiples of the composition, i.e., more dilute or more concentrated, and it will be appreciated that the compositions described herein can variously and alternatively comprise, consist or consist essentially of any combination of ingredients consistent with the disclosure herein.
  • the leaching composition described herein is capable of substantially removing noble metals from a source at room temperature without the use of high temperatures (e.g., temperatures greater than about 100°C), high pressures (e.g., pressures greater than atmospheric pressure) or electrodes to maintain the voltage of the composition in a specific range.
  • the leaching composition is more environmentally friendly than the prior art cyanide compositions and more inexpensive than tri-iodide compositions.
  • the vessel that is used to process the source to remove the noble metals can comprise any material without any concern of corrosion or degradation.
  • the noble metals can be reclaimed from the leaching composition using a number of methods including, but not limited to, electrochemical techniques such as electrowinning, and chemical reduction processes.
  • a reducing agent can be added to the leaching composition containing noble metals to cause their precipitation.
  • various reducing agents can be applied to cause selective or non-selective precipitation of noble metals. Precipitation can be done in a manner to avoid the contamination of the leaching composition, so that the leaching composition can be regenerated and reused in the next leaching cycle after the noble metals have been removed.
  • the reducing agent is a so-called environmentally friendly chemical.
  • the reduction occurs rapidly with minimal heating requirements.
  • precipitation with S0 2 is known to be selective for gold, non-contaminating to the leaching composition and inexpensive.
  • Gold is precipitated as a fine powder that is separated from the leaching solution by filtration.
  • a flocculating agent can be added to the solution at the same time as the reducing agent, if the reducing agent is in liquid or gaseous form. If the reducing agent is in the form of powder, a flocculating agent can be added after complete dissolution of the reducing agent to prevent collection of particles of the reducing agent.
  • commercially available MAGNAFLOK-351 that is typically used for concentrating finely ground gold ores, can be used. The use of a non-ionic flocculating agent is preferred to avoid the possible undesirable recovery of iodine from the composition.
  • the reducing agents can include, but are not limited to, sodium borohydride, ascorbic acid, diethyl malonate, sodium metabisulfite, polyphenon 60 (P60, green tea extract), glucose, and sodium citrate.
  • ascorbic acid introduced to a composition comprising Au 3+ ions at pH 1 produces highly pure gold metal.
  • Sodium metabisulfite (SMB) can be added to a composition comprising Au 3+ ions at pH 1 or H 7 and produce highly pure gold metal.
  • the noble metal ions can be converted to noble metals via electrowinning or electrochemical techniques. Any suitable means can be used to remove the precipitated noble metals. Settling and decanting, filtering the solution through a filter press or centrifuging are convenient procedures for such removal.
  • the leaching composition may still include leached silver and palladium ions.
  • a selective reducing agent may be added for precipitation of silver, such as hydroxylamine.
  • the use of a flocculating agent is suggested to facilitate filtration.
  • palladium can be precipitated, for example, with the use of a stabilized alkali metal borohydride and a flocculating agent.
  • the source material subsequent to leaching can be rinsed (e.g., with water) to further recover the residual leaching composition on the surface of the source material, which can contain very significant amounts of dissolved noble metals.
  • Electrowinning is a common way of gold recovery from solutions, but if the rinse water comprising dissolved gold is recovered, conventional electrowinning becomes ineffective as gold is present in rinse water in small concentrations.
  • the removal of gold from rinse water solutions can become effective if high surface area (HSA) electrodes are used for electrowinning.
  • HSA electrowinning may economically remove gold having a concentration greater than 10 ppm down to ppb level.
  • Iodide can also be oxidized and recovered using the same process if an undivided electrowinning cell is used.
  • a leaching composition comprising 30 wt% water, 29 wt% sulfuric acid (96%), 18 wt% nitric acid (70%) and 23 wt%> saturated sodium chloride was prepared.
  • the leaching composition was divided into four test tubes containing 1 Og each of the leaching composition. Gold fingers, pure Pd, pure Pt and pure Ag were added to each of the test tubes and processed as indicated and the pre- and post-weight of the noble metals determined, as summarized in Table 1.
  • the leaching composition effectively and efficiently dissolved gold and palladium and could be loaded with additional metal as more source is added to said composition.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Electrochemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

Compositions and processes for leaching noble metals from materials comprising said noble metals. Advantageously, the halide-based composition is environmentally friendly and effectively removes noble metals at room temperature without the need for high pressures and electrodes.

Description

WET BASED FORMULATIONS FOR THE SELECTIVE REMOVAL OF NOBLE
METALS
FIELD
[0001] The present invention relates generally to processes for recycling/reclaiming of noble metals, such as ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold from source materials.
DESCRIPTION OF THE RELATED ART
[0002] There are a number of sources of noble metals such as gold, silver and platinum group metals which offer the opportunity for economical recovery. For example, gold is available from ores and numerous scrap sources, including industrial wastes, gold plated electronic circuit boards, and in alloys with copper, zinc, silver or tin in the karat gold used in jewelry. Silver is available from photographic and x-ray film emulsions, scrap sterling, and numerous industrial sources. Platinum group metals are available from industrial sources, such as catalysts. There are numerous instances in which it is desirable to recover these metals from an aggregate material.
[0003] Platinum is a silvery, white, ductile metal which is insoluble in mineral and organic acids, but soluble in aqua regia. Platinum does not corrode or tarnish, and forms strong complexes with halides (i.e., chloride, bromide, fluoride and iodide). Platinum is used as a catalyst (nitric acid, sulfuric acid, and high-octane gasoline production; automobile exhaust gas converters), in laboratory ware, spinnerets for rayon and glass fiber manufacture, jewelry, dentistry, electrical contacts, thermocouples, surgical wire, bushings, electroplating, electric furnace windings, chemical reaction vessels, anti-cancer drugs and permanent magnets. Palladium is similarly a silvery, white, ductile metal which does not tarnish in air. It is the least noble (e.g., most reactive) of the platinum group, is insoluble in organic acids, but soluble in aqua regia and fused alkalies. Palladium is used as a catalyst for chemical processes including reforming cracked petroleum fractions and hydrogenation, for metallizing ceramics, as "white gold" in jewelry, in protective coatings, and in hydrogen valves (in hydrogen separation equipment). . Both platinum and palladium are good electrical conductors and are used in alloys for electrical relays in switching systems and telecommunication equipment, resistance wires and aircraft spark plugs. Further, platinum group metal applications include industrial radiography, catalysts, pen points, electrical contacts, jewelry, coatings and headlight reflectors.
[0004] Methods for the recovery of noble metals have taken many forms in the prior art. The conventional leaching of gold ores, for example, with alkaline cyanide solutions, has been widely practiced on a commercial scale, but has known disadvantages including, for example, slow leaching rates, long contact times, and toxicity associated with the use of cyanide. Other methods have included the use of aqua regia or high temperature oxidative pressure leaching. However, and in addition to well known disadvantages, aqua regia has its limitations. For example, aqua regia is unable to dissolve some noble metals, e.g., silver.
[0005] Accordingly, there has remained a need for cost-effective methods and compositions for the recovery of noble metals from a variety of sources of such metals. Thus, while prior art approaches have been successful, these methods have typically suffered from one or more disadvantages. The present disclosure is directed to methods and processes that use halide -based compositions at room temperature to efficiently remove noble metals from the source comprising same.
SUMMARY
[0006] The present invention relates generally to compositions and processes for leaching noble metals from sources comprising same including, but not limited to, ores, jewelry, scraps comprising said noble metals, waste materials, alloys, catalyst materials, and various industrial sources. More specifically, the compositions for leaching noble metals from sources are acidic, halide-based compositions that efficiently remove noble metals from the source at room temperature.
[0007] In one aspect, a leaching composition is described, said composition comprising at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent.
[0008] In another aspect, a method of removing noble metals from a source is described, said method comprising contacting said source under conditions with the leaching composition, wherein said noble metals are dissolved or otherwise solubilized in the leaching composition, and wherein the leaching composition comprises at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent.
[0009] Other aspects, features and advantages will be more fully apparent from the ensuing disclosure and appended claims.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS THEREOF
[0010] The present invention relates generally to compositions and processes for leaching noble metals from sources comprising same including, but not limited to, ores, jewelry, scraps comprising said noble metals, waste materials, alloys, catalyst materials, and various industrial sources. More specifically, the compositions for leaching noble metals from sources are acidic, halide-based compositions that efficiently remove noble metals from the source at low temperatures. [0011] As used herein, "noble metals" refers to the group of metals including gold, silver, the platinum group metals, alloys comprising same, and combinations thereof. The "platinum group metals" include ruthenium, osmium, rhodium, iridium, palladium and platinum.
[0012] As used herein, "base metals" corresponds to iron, nickel, zinc, copper, aluminum, tungsten, molybdenum, tantalum, magnesium, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium, thallium, alloys comprising same, and combinations thereof.
[0013] "Substantially devoid" is defined herein as less than 2 wt. %, preferably less than 1 wt. %, more preferably less than 0.5 wt. %, and most preferably less than 0.1 wt. %. "Devoid" corresponds to 0 wt. %.
[0014] As used herein, "about" is intended to correspond to ± 5 % of the stated value.
[0015] As used herein, "halide" corresponds to fluoride, chloride, bromide or iodide -containing species such as salts or acids.
[0016] As used herein, the "source" is a noble metal-containing material including, but not limited to, ores, jewelry, scraps comprising said noble metals, waste materials comprising said noble metals including electronic waste, alloys, catalyst materials, various industrial sources, and combinations thereof.
[0017] As used herein, "to remove" noble metals from a source means that the noble metal is substantially dissolved or solubilized or the like in the leaching composition, while base metals are not substantially dissolved or solubilized or the like. "Substantially dissolved" is defined herein more than 95 wt. % of the material originally present is dissolved or solubilized or the like, preferably more than 98 wt. %, more preferably more than 99 wt. %, and most preferably more than 99.9 wt. %. "Not substantially dissolved" is defined herein less than 5 wt. % of the material originally present is dissolved or solubilized or the like, preferably less than 2 wt. %, more preferably less than 1 wt. %, and most preferably less than 0.1 wt. %.
[0018] As used herein, the term "leaches" or "leaching" corresponds to the complete or partial removal or extraction of the gold and/or other noble metals from the source into the leaching composition. The gold or other noble metal is dissolved or otherwise solubilized in the leaching composition, preferably dissolved.
[0019] As defined herein, "crushing" the source corresponds to any method that substantially exposes the gold and other noble metals of the source material to the leaching composition, e.g., crushing, cracking, pulverizing, shredding, or grinding.
[0020] As defined herein, "agitation means" include, but are not limited to, physical agitation such as mixing, recirculation, turbulence, and combinations thereof.
[0021] Compositions may be embodied in a wide variety of specific formulations, as hereinafter more fully described. In all such compositions, wherein specific constituents of the composition are discussed in reference to weight percentage ranges including a zero lower limit, it will be understood that such constituents may be present or absent in various specific embodiments of the composition, and that in instances where such constituents are present, they may be present at concentrations as low as 0.001 weight percent, based on the total weight of the composition in which such constituents are employed.
[0022] In a first aspect, a method of removing noble metals from a source is described, wherein said noble metals are dissolved or otherwise solubilized in a leaching composition. More specifically, the method of removing noble metals from a source comprises contacting said source with a leaching composition, wherein said noble metals are dissolved or otherwise solubilized in the leaching composition. Preferably, noble metals are selectively removed relative to base metals also present in the source.
[0023] Advantageously, once a volume of a source has been processed and the noble metals removed (from the leaching composition), new volumes of the source can be added to the leaching composition and the process of removing the noble metals can be repeated again and again until the leaching composition is saturated with noble metals. Alternatively, a "feed and bleed" process may be used wherein clean leaching composition is periodically introduced to the working leaching composition with simultaneous withdrawal of some of the working leaching composition. The leaching composition comprising the noble metals can be processed to obtain useful forms of said noble metals (e.g., electrochemically, by electrowinning, or using reducing agents).
[0024] In removal applications, the leaching composition is contacted in any suitable manner to the source, e.g., by spraying the leaching composition on the source, by dipping the source in a volume of the leaching composition, by contacting the source with another material, e.g., a pad, or fibrous sorbent applicator element, that has the leaching composition absorbed thereon, by contacting the source with a recirculating composition, or by any other suitable means, manner or technique, by which the leaching composition is brought into contact with the source. It should be appreciated that the source (i.e., noble metal containing material) can be added to the leaching composition as is, pulverized into a powder, shredded into pieces, crushed, or in any other form so long as the metals contained in the source are readily exposed for removal from the source. The leaching composition and the source can be agitated such that the source is substantially exposed to the leaching composition.
[0025] In use of the leaching compositions described herein for removing noble metals from a source comprising same, the leaching composition typically is contacted with the source for a time of from about 1 min to about 120 minutes, preferably about 3 min to 60 at temperature in a range of from about 20°C to about 100°C, preferably in a range from about 20°C to about 60°C, more preferably about 20°C to about 40°C, and most preferably about room temperature. Such contacting times and temperatures are illustrative, and any other suitable time and temperature conditions may be employed that are efficacious to remove the noble metals from the source comprising same.
[0026] In a second aspect, a leaching composition is described, said leaching composition comprising, consisting of, or consisting essentially of at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent. In one embodiment, the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one chloride salt, at least one acid, and at least one solvent. In another embodiment, the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one chloride salt, at least one sulfur- containing acid, and at least one solvent. In still another embodiment, the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one alkaline chloride salt, at least one sulfur-containing acid, and at least one solvent. In yet another embodiment, the leaching composition comprises, consists of, or consists essentially of at least one nitrate salt oxidizing agent, at least one alkaline chloride salt, at least one sulfur-containing acid, and at least one solvent. The leaching composition is aqueous in nature and has a pH less than about 2, more preferably less than about 1.
[0027] In another embodiment, the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one halide salt, at least one acid, and at least one solvent, present in the following weight percentages, based on the total weight of the composition:
[0028] In still another embodiment, the leaching composition comprises, consists of, or consists essentially of at least one nitrate salt oxidizing agent, at least one alkaline chloride salt, at least one sulfur-containing acid, and at least one solvent, present in the following weight percentages, based on the total weight of the composition:
[0029] Oxidizing agents are included in the composition to oxidize the metals to be removed into an ionic form and accumulate highly soluble salts of dissolved metals. Oxidizing agents contemplated herein include, but are not limited to, ozone, nitric acid (HN03), bubbled air, cyclohexylaminosulfonic acid, , hydrogen peroxide (H202), oxone (potassium peroxymonosulfate, 2KHSO5 KHSO4 K2SO4), ammonium polyatomic salts (e.g., ammonium peroxomonosulfate, ammonium chlorite (NH4C102), ammonium chlorate (NH4CIO3), ammonium iodate (NH4IO3), ammonium perborate (NH4BO3), ammonium perchlorate (NH4CIO4), ammonium periodate (NH4IO3), ammonium persulfate ((NH4)2S20g), ammonium hypochlorite (NH4CIO)), sodium polyatomic salts (e.g., sodium persulfate (Na2S20g), sodium hypochlorite (NaCIO)), potassium polyatomic salts (e.g., potassium iodate (KIO3), potassium permanganate (KMn04), potassium persulfate, potassium persulfate potassium hypochlorite (KCIO)), tetramethylammonium polyatomic salts (e.g., tetramethylammonium chlorite ((N(CH3)4)C102), tetramethylammonium chlorate ((N(CH3)4)C103), tetramethylammonium iodate ((N(CH3)4)I03), tetramethylammonium perborate ((N(CH3)4)B03), tetramethylammonium perchlorate ((N(CH3)4)C104), tetramethylammonium periodate ((N(CH3)4)I04), tetramethylammonium persulfate ((N(CH3)4)S20g), tetramethylammonium nitrate), tetrabutylammonium polyatomic salts (e.g., tetrabutylammonium peroxomonosulfate, tetrabutylammonium nitrate), peroxomonosulfuric acid, urea hydrogen peroxide ((CO(NH2)2)H202), peracetic acid (CH3(CO)OOH), sodium nitrate, potassium nitrate, ammonium nitrate, and combinations thereof. Most preferably, the oxidizing agent comprises a nitrate ion including, but not limited to, nitric acid, sodium nitrate, potassium nitrate, ammonium nitrate, tetraalkylammonium nitrate, and combinations thereof.
[0030] The at least one halide is preferably a chloride-containing compound including, but not limited to, hydrochloric acid, and alkaline chlorides (e.g., sodium chloride, potassium chloride, rubidium chloride, cesium chloride, magnesium chloride, calcium chloride, strontium chloride, ammonium chloride, quaternary ammonium chloride salts), and combinations thereof, with the proviso that the chloride-containing compound cannot include copper chloride, chlorine gas, or a second, different halide. For example, the at least one halide is devoid of compounds such as CuCl2, Cl2, and BrCl2 ". Preferably, the at least one halide comprises an alkaline chloride, even more preferably an alkali metal chloride such as sodium chloride. The at least one halide can also include salts and/or acids comprising bromide and iodide including, but not limited to, sodium bromide, sodium iodide, potassium bromide, potassium iodide, rubidium bromide, rubidium iodide, cesium bromide, cesium iodide, magnesium bromide, magnesium iodide, calcium bromide, calcium iodide, strontium bromide, strontium iodide, ammonium bromide, ammonium iodide, quaternary ammonium bromide salts, and quaternary ammonium bromide salts. The at least one halide is preferably substantially devoid of fluoride ions.
[0031] The at least one acid is preferably a sulfur-containing species such as sulfuric acid, sulfate salts (e.g., sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate), sulfonic acid, sulfonic acid derivatives, and combinations thereof. Sulfonic acid derivatives contemplated include methanesulfonic acid (MSA), ethanesulfonic acid, 2-hydroxyethanesulfonic acid, n-propanesulfonic acid, isopropanesulfonic acid, isobutenesulfonic acid, n-butanesulfonic acid, n-octanesulfonic acid), benzenesulfonic acid, benzenesulfonic acid derivatives, and combinations thereof. Preferably, the at least one acid comprises sulfuric acid, preferably concentrated sulfuric acid.
[0032] The at least one solvent includes, but is not limited to, water, methanol, ethanol, isopropanol, butanol, pentanol, hexanol, 2-ethyl-l-hexanol, heptanol, octanol, ethylene glycol, propylene glycol, butylene glycol, tetrahydrofurfuryl alcohol (THFA), butylene carbonate, ethylene carbonate, propylene carbonate, dipropylene glycol, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol phenyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether (DPGME), tripropylene glycol methyl ether (TPGME),dipropylene glycol dimethyl ether, dipropylene glycol ethyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether (DPGPE), tripropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, 2,3-dihydrodecafluoropentane, ethyl perfluorobutylether, methyl perfluorobutylether, alkyl carbonates, alkylene carbonates, 4-methyl-2- pentanol, tetramethylene glycol dimethyl ether, and combinations thereof. Preferably, the at least one solvent comprises water.
[0033] In another embodiment, the leaching composition further comprises a corrosion inhibitor, specifically a base metal corrosion inhibitor, so as to ensure that the leaching composition selectively removes noble metals from the source relative to base metals. Accordingly, the leaching composition can comprise, consist of, or consist essentially of at least one oxidizing agent, at least one halide, at least one acid, at least one solvent, and at least one corrosion inhibitor. In one embodiment, the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one chloride salt, at least one acid, at least one solvent, and at least one corrosion inhibitor. In another embodiment, the leaching composition comprises, consists of, or consists essentially of at least one oxidizing agent, at least one chloride salt, at least one sulfur-containing acid, at least one solvent, and at least one corrosion inhibitor. Corrosion inhibitors for passivating the base metals include, but are not limited to, ascorbic acid, adenosine, adenine, L(+)-ascorbic acid, isoascorbic acid, ascorbic acid derivatives, citric acid, ethylenediamine, gallic acid, oxalic acid, tannic acid, ethylenediaminetetraacetic acid (EDTA), uric acid, 1,2,4-triazole (TAZ), triazole derivatives (e.g., benzotriazole (BTA), tolyltriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole, 3-amino-5- mercapto- 1,2,4-triazole, 1 -amino- 1,2,4-triazole, hydroxybenzotriazole, 2-(5-amino-pentyl)- benzotriazole, l-amino-l,2,3-triazole, l-amino-5-methyl-l,2,3-triazole, 3-amino-l,2,4-triazole, 3- mercapto-l,2,4-triazole, 3-isopropyl-l,2,4-triazole, 5-phenylthiol-benzotriazole, halo-benzotriazoles (halo = F, CI, Br or I), naphthotriazole), 2-mercaptobenzimidazole (MBI), 2-mercaptobenzothiazole, 4-methyl-2-phenylimidazole, 2-mercaptothiazoline, 5-aminotetrazole (ATA), 5 -amino -1,3,4 - thiadiazole-2-thiol, 2,4-diamino-6-methyl-l,3,5-triazine, thiazole, triazine, methyltetrazole, 1,3- dimethyl-2-imidazolidinone, 1 ,5-pentamethylenetetrazole, 1 -phenyl-5-mercaptotetrazole, diaminomethyltriazine, imidazoline thione, mercaptobenzimidazole, 4-methyl-4H-l,2,4-triazole-3- thiol, 5-amino-l,3,4-thiadiazole-2-thiol, benzothiazole, and combinations thereof. Most preferably, the passivating agent comprises BTA, TAZ, triazole derivatives, or combinations thereof.
[0034] The leaching composition of the second aspect can further comprise noble metal chelators, surfactants, defoamers, and combinations thereof, as readily determined by the person skilled in the art.
[0035] In a particularly preferred embodiment, the leaching composition comprises, consists of, or consists essentially of sodium chloride, sulfuric acid, nitric acid, and water, with the proviso that the leaching composition is substantially devoid of hydrogen peroxide, copper (II) chloride, chlorine gas, BrCl2 ~, fluoride-containing compounds, hydroxide -containing compounds, ferrous ions, a sulfur compound comprising a sulfur atom with an oxidation state in the range of -2 to +5, and cyanides.
[0036] It should be appreciated that when the leaching composition comprises a nitrate such as nitric acid, during the leaching of the noble metals from the source, NOx gases can be emitted. Accordingly, preferably the leaching process is carried out in a system comprising a condenser, wherein the NOx gases can be collected and converted back into nitric acid, as readily known to the person skilled in the art. As understood by the person skilled in the art, "NOx" corresponds to mononitrogen oxides such as NO and N02.
[0037] Advantageously, the leaching composition is easily recyclable and can be employed in a closed-loop process generating minimal waste. For example, once the leaching composition has been exposed to the source and noble metals have been removed from the source, the resulting leaching composition including the noble metals can be recycled by reclaiming the noble metals. The recycled leaching solution can be reused, with or without the addition of fresh leaching composition chemistry. When necessary to dispose of, the leaching composition is essentially non-toxic once the noble metals are reclaimed and the excess acidity neutralized.
[0038] The leaching compositions described herein are easily formulated by simple addition of the respective ingredients and mixing to homogeneous condition. Furthermore, the leaching composition may be readily formulated as single-package formulations or multi-part formulations that are mixed at or before the point of use, e.g., the individual parts of the multi-part formulation may be mixed at the tool or in a storage tank upstream of the tool. The concentrations of the respective ingredients may be widely varied in specific multiples of the composition, i.e., more dilute or more concentrated, and it will be appreciated that the compositions described herein can variously and alternatively comprise, consist or consist essentially of any combination of ingredients consistent with the disclosure herein.
[0039] Advantageously, the leaching composition described herein is capable of substantially removing noble metals from a source at room temperature without the use of high temperatures (e.g., temperatures greater than about 100°C), high pressures (e.g., pressures greater than atmospheric pressure) or electrodes to maintain the voltage of the composition in a specific range. Moreover, the leaching composition is more environmentally friendly than the prior art cyanide compositions and more inexpensive than tri-iodide compositions. For example, the vessel that is used to process the source to remove the noble metals can comprise any material without any concern of corrosion or degradation.
[0040] The noble metals can be reclaimed from the leaching composition using a number of methods including, but not limited to, electrochemical techniques such as electrowinning, and chemical reduction processes. For example, a reducing agent can be added to the leaching composition containing noble metals to cause their precipitation. Depending on the noble metal content, various reducing agents can be applied to cause selective or non-selective precipitation of noble metals. Precipitation can be done in a manner to avoid the contamination of the leaching composition, so that the leaching composition can be regenerated and reused in the next leaching cycle after the noble metals have been removed. Preferably, the reducing agent is a so-called environmentally friendly chemical. Moreover, preferably the reduction occurs rapidly with minimal heating requirements. For example, precipitation with S02 is known to be selective for gold, non-contaminating to the leaching composition and inexpensive. Gold is precipitated as a fine powder that is separated from the leaching solution by filtration. To facilitate filtration, a flocculating agent can be added to the solution at the same time as the reducing agent, if the reducing agent is in liquid or gaseous form. If the reducing agent is in the form of powder, a flocculating agent can be added after complete dissolution of the reducing agent to prevent collection of particles of the reducing agent. For separation of gold powder, commercially available MAGNAFLOK-351 (Ciba Specialty Chemicals) that is typically used for concentrating finely ground gold ores, can be used. The use of a non-ionic flocculating agent is preferred to avoid the possible undesirable recovery of iodine from the composition.
[0041] Alternatively, the reducing agents can include, but are not limited to, sodium borohydride, ascorbic acid, diethyl malonate, sodium metabisulfite, polyphenon 60 (P60, green tea extract), glucose, and sodium citrate. For example, as introduced in International Patent Application No. PCT/US11/48449 filed on August 19, 2011 and entitled "Sustainable Process for Reclaiming Precious Metals and Base Metals from e-Waste," which is hereby incorporated by reference herein in its entirety, ascorbic acid introduced to a composition comprising Au3+ ions at pH 1 produces highly pure gold metal. Sodium metabisulfite (SMB) can be added to a composition comprising Au3+ ions at pH 1 or H 7 and produce highly pure gold metal. Alternatively, the noble metal ions can be converted to noble metals via electrowinning or electrochemical techniques. Any suitable means can be used to remove the precipitated noble metals. Settling and decanting, filtering the solution through a filter press or centrifuging are convenient procedures for such removal.
[0042] After separation of the solid gold by filtering, centrifugation or any other appropriate method, the leaching composition may still include leached silver and palladium ions. A selective reducing agent may be added for precipitation of silver, such as hydroxylamine. The use of a flocculating agent is suggested to facilitate filtration. After separation of precipitated silver, palladium can be precipitated, for example, with the use of a stabilized alkali metal borohydride and a flocculating agent.
[0043] It should be appreciated that the source material subsequent to leaching can be rinsed (e.g., with water) to further recover the residual leaching composition on the surface of the source material, which can contain very significant amounts of dissolved noble metals.
[0044] Electrowinning is a common way of gold recovery from solutions, but if the rinse water comprising dissolved gold is recovered, conventional electrowinning becomes ineffective as gold is present in rinse water in small concentrations. The removal of gold from rinse water solutions can become effective if high surface area (HSA) electrodes are used for electrowinning. HSA electrowinning may economically remove gold having a concentration greater than 10 ppm down to ppb level. Iodide can also be oxidized and recovered using the same process if an undivided electrowinning cell is used.
[0045] The features and advantages of the invention are more fully illustrated by the following non- limiting examples, wherein all parts and percentages are by weight, unless otherwise expressly stated.
Example 1
[0046] 40 g of a leaching composition comprising 30 wt% water, 29 wt% sulfuric acid (96%), 18 wt% nitric acid (70%) and 23 wt%> saturated sodium chloride was prepared. The leaching composition was divided into four test tubes containing 1 Og each of the leaching composition. Gold fingers, pure Pd, pure Pt and pure Ag were added to each of the test tubes and processed as indicated and the pre- and post-weight of the noble metals determined, as summarized in Table 1.
[0047] It can be seen that the leaching composition effectively and efficiently dissolved gold and palladium and could be loaded with additional metal as more source is added to said composition.
[0048] Although the invention has been variously disclosed herein with reference to illustrative embodiments and features, it will be appreciated that the embodiments and features described hereinabove are not intended to limit the invention, and that other variations, modifications and other embodiments will suggest themselves to those of ordinary skill in the art, based on the disclosure herein. The invention therefore is to be broadly construed, as encompassing all such variations, modifications and alternative embodiments within the spirit and scope of the claims
hereafter set forth.

Claims

THE CLAIMS What is claimed is:
1. A leaching composition comprising, at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent.
2. The leaching composition of claim 1 , wherein the composition includes a pH of less than about 2.
3. The leaching composition of claims 1 or 2, wherein the at least one oxidizing agent comprises at least one species selected from the group consisting of ozone, nitric acid (HNO3), bubbled air, cyclohexylaminosulfonic acid, , hydrogen peroxide (H2O2), oxone, ammonium peroxomonosulfate, ammonium chlorite (NH4CIO2), ammonium chlorate (NH4CIO3), ammonium iodate (NH4IO3), ammonium perborate (NH4B03), ammonium perchlorate (NH4C104), ammonium periodate (NH4I03), ammonium persulfate ((NH4)2S208), ammonium hypochlorite (NH4C10), sodium persulfate (Na2S208), sodium hypochlorite (NaCIO)), potassium polyatomic salts (e.g., potassium iodate (KI03), potassium permanganate (KMn04), potassium persulfate, potassium persulfate (K2S208), potassium hypochlorite (KCIO), tetramethylammonium chlorite ((N(CH3)4)C102), tetramethylammonium chlorate ((N(CH3)4)C103), tetramethylammonium iodate ((N(CH3)4)I03), tetramethylammonium perborate ((N(CH3)4)B03), tetramethylammonium perchlorate ((N(CH3)4)C104), tetramethylammonium periodate ((N(CH3)4)I04), tetramethylammonium persulfate ((N(CH3)4)S208), tetrabutylammonium peroxomonosulfate, peroxomonosulfuric acid, urea hydrogen peroxide ((CO(NH2)2)H202), peracetic acid (CH3(CO)OOH), sodium nitrate, potassium nitrate, ammonium nitrate, and combinations thereof.
4. The leaching composition of any of the preceding claims, wherein the at least one oxidizing agent comprises a nitrate salt selected from the group consisting of nitric acid, sodium nitrate, potassium nitrate, ammonium nitrate, tetraalkylammonium nitrate, and combinations thereof, preferably nitric acid.
5. The leaching composition of any of the preceding claims, wherein the at least one halide comprises an alkaline chloride.
6. The leaching composition of any of the preceding claims, wherein the at least one halide comprises a chloride species selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, magnesium chloride, calcium chloride, strontium chloride, ammonium chloride, quaternary ammonium chloride salts, and combinations thereof, with the proviso that the chloride species cannot include copper chloride, chlorine gas, or a second, different halide in the compound, preferably sodium chloride.
7. The leaching composition of any of the preceding claims, wherein the at least one acid is a sulfur- containing acid.
8. The leaching composition of any of the preceding claims, wherein the at least one acid comprises a species selected from the group consisting of sulfuric acid, sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate, sulfonic acid, sulfonic acid derivatives, and combinations thereof, preferably sulfuric acid.
9. The leaching composition of any of the preceding claims, wherein the composition further comprises at least one of surfactants, defoamers, and combinations thereof.
10. The leaching composition of claim 1, wherein the composition comprises nitric acid, sodium chloride, sulfuric acid, and water.
11. The leaching composition of any of the preceding claims, wherein the composition further comprises at least one corrosion inhibitor.
12. The leaching composition of any of the preceding claims, wherein the leaching composition is substantially devoid of hydrogen peroxide, fluoride -containing compounds, CuCl2, Cl2, BrCl2 ", hydroxide-containing compounds, ferrous ions, a sulfur compound comprising a sulfur atom with an oxidation state in the range of -2 to +5, and cyanides.
13. A method of removing noble metals from a source, said method comprising contacting said source under conditions with the leaching composition of any of claims 1-12, wherein said noble metals are dissolved or otherwise solubilized in the leaching composition.
14. The method of claim 13, wherein the noble metals are selectively removed relative to base metals also present in the source.
15. The method of claims 13 or 14, wherein the source is selected from the group consisting of ores, jewelry, scraps comprising noble metals, waste materials comprising noble metals, electronic waste materials comprising noble metals, alloys, catalyst materials, and industrial sources.
16. The method of any of claims 13-15, wherein the source is crushed, cracked, pulverized, shredded, or ground to expose the noble metals.
17. The method of any of claims 13-16, wherein the leaching composition and source are agitated such that the source is substantially exposed to the leaching composition.
18. The method of any of claims 13-17, wherein the conditions are selected from the group consisting of time of from about 1 min to about 120 minutes, temperature in a range of from about 20°C to about 100°C, and combinations thereof.
19. The method of any of claims 13-18, wherein the conditions comprise temperature of about 20°C to about 60°C.
20. The method of any of claims 13-19, further comprising reclaiming the noble metals from the leaching composition by electrochemical techniques such as electrowinning, or chemical reduction processes.
21. The method of any of claims 13-20, wherein the removal of noble metals from the source is effectuated at temperatures less than about 100°C, pressures not greater than atmospheric pressure, and without the use of electrodes.
22. The method of any of claims 13-21, wherein the noble metals comprise a species selected from the group consisting of gold, silver, ruthenium, osmium, rhodium, iridium, palladium, platinum, alloys comprising same, and combinations thereof.
23. The method of any of claims 14-22, wherein the base metals comprise a species selected from the group consisting of iron, nickel, zinc, copper, aluminum, tungsten, molybdenum, tantalum, magnesium, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium, thallium, alloys comprising same, and combinations thereof.
EP15755407.2A 2014-02-25 2015-02-23 Wet based formulations for the selective removal of noble metals Withdrawn EP3110982A4 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201461944366P 2014-02-25 2014-02-25
PCT/US2015/017088 WO2015130607A1 (en) 2014-02-25 2015-02-23 Wet based formulations for the selective removal of noble metals

Publications (2)

Publication Number Publication Date
EP3110982A1 true EP3110982A1 (en) 2017-01-04
EP3110982A4 EP3110982A4 (en) 2017-11-22

Family

ID=54009528

Family Applications (1)

Application Number Title Priority Date Filing Date
EP15755407.2A Withdrawn EP3110982A4 (en) 2014-02-25 2015-02-23 Wet based formulations for the selective removal of noble metals

Country Status (7)

Country Link
US (1) US20160362804A1 (en)
EP (1) EP3110982A4 (en)
KR (1) KR20160127088A (en)
CN (1) CN106661663A (en)
CA (1) CA2943992A1 (en)
TW (1) TW201602357A (en)
WO (1) WO2015130607A1 (en)

Families Citing this family (34)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102338550B1 (en) 2013-06-06 2021-12-14 엔테그리스, 아이엔씨. Compositions and methods for selectively etching titanium nitride
WO2015095175A1 (en) 2013-12-16 2015-06-25 Advanced Technology Materials, Inc. Ni:nige:ge selective etch formulations and method of using same
TWI662379B (en) 2013-12-20 2019-06-11 Entegris, Inc. Use of non-oxidizing strong acids for the removal of ion-implanted resist
EP3083016B1 (en) * 2013-12-20 2020-07-29 Greene Lyon Group Inc. Method and apparatus for recovery of noble metals, including recovery of noble metals from plated and/or filled scrap
WO2015103146A1 (en) 2013-12-31 2015-07-09 Advanced Technology Materials, Inc. Formulations to selectively etch silicon and germanium
TWI659098B (en) 2014-01-29 2019-05-11 Entegris, Inc. Chemical mechanical polishing formula and its use method
EP2985354B1 (en) * 2014-11-10 2016-10-19 Heraeus Deutschland GmbH & Co. KG Method for removing noble metal from a catalyst support containing noble metals
EP3064602A1 (en) * 2015-03-05 2016-09-07 Heraeus Deutschland GmbH & Co. KG Method for the production of elemental rhodium
JP6893621B2 (en) 2015-04-21 2021-06-23 エクシール ワークス コーポレイション A method for selectively leaching and extracting precious metals in organic solvents
JP2018524480A (en) 2015-06-24 2018-08-30 グリーン リヨン グループ, インコーポレーテッドGreene Lyon Group, Inc. Applications related to selective extraction of precious metals using acidic fluids including nitrate-containing fluids
WO2017033915A1 (en) * 2015-08-26 2017-03-02 株式会社Adeka Etching liquid composition and etching method
US10920143B2 (en) 2015-08-26 2021-02-16 Adeka Corporation Etching liquid composition and etching method
CN106498159B (en) * 2016-10-24 2018-07-03 黄奇向 A kind of gold, silver and bronze mineral dressing additive and its production method and application method
WO2019178051A1 (en) * 2018-03-12 2019-09-19 Jabil Inc. Precious metals recovery processes
IT201800005160A1 (en) * 2018-05-08 2019-11-08 METHOD FOR THE RECOVERY OF METALLIC GOLD
US11441229B2 (en) 2018-07-06 2022-09-13 Entegris, Inc. Method for selectively removing nickel platinum material
CN109811138B (en) * 2018-11-05 2021-04-09 贵研铂业股份有限公司 Method for recovering iridium from iridium-containing organic waste liquid
KR102648664B1 (en) * 2018-12-04 2024-03-19 삼성디스플레이 주식회사 Etchant composition, and method for manufacturing metal pattern and array substrate using the same
CN109609783B (en) * 2018-12-22 2020-11-10 励福(江门)环保科技股份有限公司 Method for efficiently separating and purifying palladium and rhodium from alloy sheet containing palladium and rhodium alloy
CN109943718A (en) * 2019-04-11 2019-06-28 昆明理工大学 A kind of halide gold extracting method using persulfate as oxidant
CN110006987B (en) * 2019-05-06 2021-09-21 甘肃有色冶金职业技术学院 Method for continuously detecting gold, palladium, platinum, rhodium, iridium and ruthenium in alloy
FR3096833B1 (en) 2019-05-29 2022-03-04 Rosi process for recycling the silver present on a photovoltaic cell
US11666955B2 (en) 2019-09-04 2023-06-06 Jabil Inc. System and method for obtaining mineral rich powder from electronic waste
CN110669939A (en) * 2019-11-12 2020-01-10 长春黄金研究院有限公司 A method of recycling gold from wafer waste
CN110964925B (en) * 2019-12-23 2021-05-07 昆明理工大学 A kind of method of recycling nickel-based superalloy
EP4192989A4 (en) * 2020-08-07 2025-12-17 Excir Works Corp Leaching and recovery processes for platinum group metals in organic solvents
KR102537715B1 (en) * 2021-02-25 2023-05-31 김지열 Metal stripping agent composition and the metal stripping method by using the same
US11649524B2 (en) 2021-05-03 2023-05-16 Phoenix Tailings Inc. Noble metal extraction method and apparatus
FR3126892B1 (en) * 2021-09-16 2025-03-07 Commissariat Energie Atomique PROCESS FOR SELECTIVE RECOVERY OF GOLD BY GREEN CHEMISTRY FROM AN ELEMENT CONTAINING GOLD AND A PLATINUM
US20240417824A1 (en) * 2021-10-22 2024-12-19 Ph7 Technologies Inc. Solvents and methods for leaching precious metals
JP7478719B2 (en) * 2021-11-29 2024-05-07 田中貴金属工業株式会社 Method and apparatus for dissolving and stripping precious metals
JP2023147810A (en) * 2022-03-30 2023-10-13 アサヒプリテック株式会社 Recycled palladium manufacturing method
DE102022111440B3 (en) * 2022-05-09 2022-08-25 Technische Universität Bergakademie Freiberg, Körperschaft des öffentlichen Rechts Process for recovering ruthenium from a ruthenium-containing material
CN117089827B (en) * 2023-07-18 2026-04-03 深圳市松柏科工股份有限公司 A method for using palladium removal solution

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US136102A (en) * 1873-02-18 Improvement in treating ores of silver
US732641A (en) * 1902-09-10 1903-06-30 Thomas B Joseph Metal-leaching process.
US3256092A (en) * 1962-03-05 1966-06-14 Gen Aniline & Film Corp Corrosion inhibitors in bleach solutions
US4244735A (en) * 1979-07-27 1981-01-13 Hazen Research, Inc. Chloride leach process for recovering metal values in the presence of arsenic
EP0124213A1 (en) * 1983-02-25 1984-11-07 Hydromet Mineral (Uk) Limited Extraction process
SE452169B (en) * 1984-03-06 1987-11-16 Boliden Ab PROCEDURE FOR EXPLOITING THE METAL WORLD OF IRON-INHALING MATERIAL
US4668289A (en) * 1985-11-22 1987-05-26 Wisconsin Alumni Research Foundation Method for reclaiming gold
FR2705102B1 (en) * 1993-05-12 1995-08-11 Rhone Poulenc Chimie PROCESS FOR TREATING COMPOSITIONS CONTAINING PRECIOUS METALS AND OTHER VALUABLE ELEMENTS FOR THEIR RECOVERY.
GB2370567B (en) * 2000-11-01 2005-05-04 Lee Fisher Robinson Extraction processes
US6551378B2 (en) * 2001-02-20 2003-04-22 Green Mineral Products Llc Recovery of precious metals from low concentration sources
US7067090B2 (en) * 2002-10-25 2006-06-27 South Dakota School Of Mines And Technology Recovery of platinum group metals
WO2011156861A1 (en) * 2010-06-15 2011-12-22 The University Of Queensland Method of recovering a metal
CN103388080B (en) * 2013-07-18 2014-12-24 中海油太原贵金属有限公司 Method for recovering and separating platinum and palladium from palladium-based adsorption net

Also Published As

Publication number Publication date
KR20160127088A (en) 2016-11-02
WO2015130607A1 (en) 2015-09-03
CN106661663A (en) 2017-05-10
US20160362804A1 (en) 2016-12-15
EP3110982A4 (en) 2017-11-22
TW201602357A (en) 2016-01-16
CA2943992A1 (en) 2015-09-03

Similar Documents

Publication Publication Date Title
WO2015130607A1 (en) Wet based formulations for the selective removal of noble metals
KR101620133B1 (en) Method for recycling of obsolete printed circuit boards
AU2017281847B2 (en) Methods, materials and techniques for precious metal recovery
KR101076418B1 (en) Method for recycling Pb-free solder waste
KR101336121B1 (en) Method for recycling Pb-free solder waste using hydrochloric acid
JP2005126800A (en) Method for leaching reduced soot containing selenium and tellurium
JP6159297B2 (en) Silver recovery method
KR100713660B1 (en) Purification method of high purity silver from silver scrap
JP7430871B2 (en) How to separate tin from tin-containing materials
JP7525340B2 (en) How to recover precious metals
JP2003105456A (en) Silver production method
JP6442674B2 (en) Method for producing platinum group hydrochloric acid solution
JP6264566B2 (en) Method for producing leaching product liquid containing platinum group element
JP7247050B2 (en) Method for treating selenosulfuric acid solution
WO2004085687A1 (en) Method for selectively extracting gold from gold-bearing materials
JP3837029B2 (en) Silver recovery method
JP2020196921A (en) Chlorination leaching method
JP5565339B2 (en) Effective chlorine removal method and cobalt recovery method
JP2025014469A (en) How to recover rhodium
JP2001192878A (en) Precious metal recovery method from metal composition
EP2052092B1 (en) A method for recovering noble metals
JP2022026823A (en) Method for recovering valuable metal
BR102018073025A2 (en) SILVER RECOVERY PROCESS ON PRINTED WIRING PLATES
Lancellotti et al. Environmentally Friendly Processes for the Recovery of Gold from Waste Electrical and Electronic Equipment (WEEE): A Review
JP2016098400A (en) Method for removing impurity from rhodium-containing solution

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20160923

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAX Request for extension of the european patent (deleted)
A4 Supplementary search report drawn up and despatched

Effective date: 20171019

RIC1 Information provided on ipc code assigned before grant

Ipc: C22B 3/06 20060101ALI20171013BHEP

Ipc: C22B 3/04 20060101AFI20171013BHEP

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20180519