EP4151763A1 - Verfahren zur selektiven rückgewinnung von gold durch grüne chemie aus einem element, das gold und ein platinoid enthält - Google Patents

Verfahren zur selektiven rückgewinnung von gold durch grüne chemie aus einem element, das gold und ein platinoid enthält Download PDF

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Publication number
EP4151763A1
EP4151763A1 EP22195178.3A EP22195178A EP4151763A1 EP 4151763 A1 EP4151763 A1 EP 4151763A1 EP 22195178 A EP22195178 A EP 22195178A EP 4151763 A1 EP4151763 A1 EP 4151763A1
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EP
European Patent Office
Prior art keywords
gold
ionic liquid
solution
process according
platinoid
Prior art date
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Pending
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EP22195178.3A
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English (en)
French (fr)
Inventor
Emmanuel BILLY
Sandrine Dourdain
Sophie LEGEAI
Hakima MENDIL-JAKANI
Benoît VILLEMEJEANNE
Eric Meux
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.)
Centre National de la Recherche Scientifique CNRS
Universite de Lorraine
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Centre National de la Recherche Scientifique CNRS
Commissariat a lEnergie Atomique CEA
Universite de Lorraine
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Publication of EP4151763A1 publication Critical patent/EP4151763A1/de
Pending legal-status Critical Current

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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
    • 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
    • C22B3/045—Leaching using electrochemical 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
    • 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
    • C22B3/12—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic alkaline solutions

Definitions

  • the present invention relates to the general field of the recovery and upgrading of gold from a support containing other elements, and in particular precious metals such as platinum.
  • the invention relates to a process for the selective recovery of gold.
  • the invention is particularly advantageous since it makes it possible to selectively recover the gold even if the waste contains PGMs.
  • the invention finds applications in numerous industrial fields, and in particular for the recovery of gold from waste or residue originating from waste electrical and electronic equipment (WEEE).
  • WEEE waste electrical and electronic equipment
  • small electronic and telecommunications equipment has the richest metallic fraction. They can contain up to 40 different metals including precious metals, in particular, gold and palladium represent more than 80% of the economic value of this waste.
  • gold and palladium make it possible to make stainless contacts or welds and are also present in electronic components (resistors, capacitors, etc.).
  • the gold and palladium contents of this waste are generally much higher than those found in the mines.
  • the gold content of electronic boards is between 10g/t and 1,000 g/t, whereas the gold content of gold mines reaches 10g/t in the richest underground mines and only 1g/t in the mines open air.
  • the palladium content varies between 5 and 100 g/t in electronic boards and peaks at 7 g/t in underground mines.
  • the WEEE recycling process conventionally comprises three major steps: collection, disassembly in order to be able to recover the elements of the WEEE containing the highest content of recoverable elements and the treatment implementing physico-chemical processes to recover the metallic phases.
  • the DEES part of interest is ground to obtain particles.
  • a separation phase makes it possible to recover the fraction of non-ferrous metals (by eddy current or magnetic separation for example). This fraction is then treated by mixed processes coupling pyrometallurgy and hydrometallurgy.
  • Blast furnaces intended for the exploitation of copper ores are used for the heat treatment phase.
  • a series of pyrometallurgical steps make it possible to incinerate the residual plastics but also to recover certain metals in the form of salts or oxides (Zn, Fe, etc.).
  • Zn, Fe, etc. salts or oxides
  • This phase is then treated by electrolysis to obtain, on the one hand, high purity copper cathodes and, on the other hand, an anode mud loaded with gold, platinoids and silver.
  • Ionic liquids are solvents with a wide electrochemical window, liquid at room temperature, extremely stable and allowing applications in air. They have a very low vapor pressure, which reduces worker exposure and limits unwanted solvent losses. They also have superior complexation and dissolution properties to organic solvents. It has already been demonstrated that it is possible to recover certain metals in an ionic liquid medium.
  • the article byffy et al. (“Recovery of Silver and Gold From Electronic Waste by Electrodeposition in Ethaline Ionic Liquid”, REV. CHIM. (Bucharest) (2020), 71, n°l, 122-132 ) describes the use of an electrochemical process for dissolving and recovering gold and silver.
  • the precious concentrate (Ag 39.7wt and Au 18.9%) is subjected to an electrodissolution step (anodic dissolution) in a mixture of ethaline and iodine.
  • Iodine has the ability to oxidize most elements, including precious metals like gold. Since gold and silver have deposition potentials, it is possible to electrodeposit them separately.
  • Cathodic deposits are 30-70% gold and 99% silver Ag respectively.
  • An object of the present invention is to propose a method, remedying the drawbacks of the prior art, making it possible to selectively recover gold from a support comprising gold and at least one platinoid chosen from platinum, palladium, rhodium and ruthenium, the process having to be simple to implement, comprising few steps and involving mild conditions in terms of temperature, while limiting energy and reprocessing costs, in order to be able to be transposed to a scale industrial.
  • the support may contain one or more platinoids, optionally in the form of metal oxide.
  • an oxidant is used.
  • the oxidant is iron chloride.
  • the support can be electrically conductive or electrically insulating.
  • the carrier may be in particulate form.
  • This first embodiment variant is particularly advantageous in the case where it is not possible to shape the support in a form compatible with an electrochemical process.
  • the method is carried out electrochemically.
  • the gold can be simultaneously electrodissolved at the anode and electrodeposited to recover it in metallic form at the cathode (counter-electrode).
  • the potential applied is between 0.3 V and 0.8 V vs Ag + /Ag.
  • the concentration of complexing ionic liquid is advantageously less than or equal to 1 mol/L.
  • the selective dissolution of the gold takes place at a temperature between 10°C and 150°C, preferably between 20°C and 90°C, and even more preferably between 30°C and 80°C, the solution of ionic liquid preferably being stirred.
  • a temperature between 10°C and 150°C, preferably between 20°C and 90°C, and even more preferably between 30°C and 80°C, the solution of ionic liquid preferably being stirred.
  • the cation of the complexing ionic liquid is chosen from a pyrrolidinium, an ammonium and an imidazolium, advantageously an N,N- dialkylimidazolium.
  • the complexing ionic liquid is 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]).
  • the liquid solution further comprises 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][NTf 2 ]).
  • the platinoid is palladium.
  • the support is waste electrical and electronic equipment, for example an electronic card.
  • the invention particularly finds applications in the field of electrical and electronic equipment and, more particularly, for the recovery of gold present in waste or a residue originating from waste electrical equipment. and electronics.
  • the process could be applied to any other element containing gold.
  • it could be a.... or a....
  • the element is immersed in the ionic liquid solution in the presence of an oxidant.
  • This embodiment is particularly advantageous when it is not desired or not possible to shape the element in the form of an electrode or even to deposit it on an electrically conductive substrate.
  • oxidant is meant a species capable of oxidizing the gold contained in the element in ionic form.
  • the oxidant is in particular a metal salt.
  • An iron salt will preferably be chosen, in particular iron chloride, for example in the form of iron(III) chloride hexahydrate (FeCl 3 .6H 2 O).
  • the dissolved gold can be deposited or electrodeposited on a support during a subsequent step.
  • the gold can thus be deposited on a support immersed in the ionic liquid solution.
  • a support immersed in the ionic liquid solution may be a vitreous carbon or platinum support.
  • the oxidation of the reducer and the reduction of the oxidant make it possible to form new oxidant/reducer species and/or to regenerate the species initially present in solution.
  • the process is economical since the redox couple in solution simultaneously performs the redox reactions, so that the consumption of reagent is zero; the solution can be used for a new cycle.
  • the pair of redox species is a metal pair, preferably chosen from Mn 2+ /Mn 3+ , Co 2+ /Co 3+ , Cr 2+ /Cr 3+ , Cr 3+ /Cr 6+ , V 2+ /V 3+ , V 4+ /V 5+ , Sn 2+ /Sn 4+ , Ag + /Ag 2+ , Cu + /Cu 2+ , Ru 4+ /Ru 8+ or Fe 2+ /Fe 3+ , a couple of organic molecules, a couple of metallocenes such as Fc/Fc + , or a couple of halogenated molecules such as for example Cl 2 /Cl - or Cl - /Cl 3 - .
  • Fe 2+ /Fe 3+ will be chosen.
  • the latter are soluble in their two oxidation states, they are not toxic, they do not degrade the ionic liquid and they have adequate redox potentials.
  • the element acts as a working electrode (also called anode or positive electrode).
  • a counter-electrode also called cathode or negative electrode
  • a reference electrode are also immersed in the solution of ionic liquid so as to form an electrochemical cell.
  • a potential is applied between the element and the counter electrode, whereby the gold is electrodissolved in solution and electrodeposited in metallic form on the counter electrode in a unit step. Alternatively, it would be possible to apply a current.
  • the application of potential (or current) to the positive electrode (or to the negative electrode) simultaneously generates the electro-dissolution of gold at the positive electrode and the electrodeposition/recovery of gold under metallic form to the negative electrode.
  • the gold extraction step simultaneously allows the recovery of the gold in metallic form and the regeneration of the ionic liquid solution, for example for use in a new treatment cycle.
  • the conductive substrate on which the element is deposited is for example made of indium oxide doped with tin, vitreous carbon, stainless steel, titanium or a noble metal.
  • the counter-electrode can be glassy carbon, stainless steel, carbon, titanium, noble metals, indium oxide doped with tin, platinum, a gold surface.
  • the reference electrode is an electrode of the Ag + /Ag type, for example produced by bringing a silver wire into equilibrium with a solution comprising the complexing ionic liquid and silver thiocyanate (AgSCN).
  • the ionic liquid solution could also comprise an oxidant or an electrochemical shuttle.
  • the ionic liquid solution may contain one or more ionic liquids.
  • the ionic liquid solution comprises two ionic liquids: a complexing ionic liquid and a solvent ionic liquid.
  • ionic liquid By ionic liquid is meant the association comprising at least one cation and one anion which generates a liquid with a melting point below or close to 100°C.
  • complexing ionic liquid is meant an ionic liquid which promotes the electro-dissolution of the gold and which has a power of complexation on the gold. The latter must also avoid the dissolution of the palladium.
  • solvent ionic liquid an ionic liquid which does not allow the dissolution of precious metals and which has no or very little complexation power.
  • the cation of the complexing ionic liquid and the cation of the solvent ionic liquid are independently chosen from the following families: imidazolium, pyrrolidinium, ammonium, piperidinium and phosphonium.
  • the solvent ionic liquid and the complexing ionic liquid have the same cation to increase the solubility of the complexing ionic liquid in the solvent ionic liquid.
  • the cation of the complexing ionic liquid is an imidazolium cation.
  • the cation of the complexing ionic liquid and the cation of the solvent ionic liquid are imidazolium.
  • This cation is stable up to a sufficiently large cathodic potential to consider an electrochemical deposit of gold when the conditions of mixing and association of ionic liquids are respected (in terms of nature of anion and concentration).
  • An N,N -dialkylimidazolium will advantageously be chosen, and preferably 1-butyl-3-methylimidazolium (BMIM). This cation has a good viscosity and a good diffusion coefficient, which promotes the movement of species in the ionic liquid solution.
  • the anion of the complexing ionic liquid is the thiocyanate anion. This anion favors the dissolution of the gold, without dissolving the palladium. In the case of a mixture of ionic liquids, it will preferably be between 1%mol and 50%mol, to improve the transport properties of the medium, and more efficient the electrochemical process (resistance, ionic conductivity, viscosity, diffusion of species, etc.)
  • the anion of the solvent ionic liquid can be organic or inorganic.
  • the anion of the ionic liquid solvent has no or very little complexing affinity, which excludes the anions having a role of ligand on the precious metals: halides, amines and/or sulphur.
  • anions will be used which make it possible to obtain a wide electrochemical window, a low viscosity, a low melting temperature (liquid at room temperature), good solubility with the complexing ionic liquid and/or not leading to hydrolysis (degradation) of the ionic liquid.
  • the TFSI anion will be chosen for the solvent ionic liquid.
  • the ionic liquid solution may also comprise a drying agent and/or an agent which promotes the transport of matter.
  • the drying agent is for example a salt which does not intervene in the reactions at the electrodes and which does not react with the solvent.
  • the drying agent can be chosen from MgSO 4 , Na 2 SO 4 , CaCl 2 , CaSO 4 , K 2 CO 3 , NaOH, KOH and CaO.
  • the agent promoting the transport properties can be a salt, a third ionic liquid or deep eutectic solvent (DES for "deep eutectic solvent”), water or another organic solvent.
  • DES deep eutectic solvent
  • Example 1 Study of the electrochemical dissolution of an Au/Pd- electrode
  • the electrochemical dissolution tests of the anode were carried out under potentiostatic control for 1000s, i.e. by applying a fixed potential E, located beyond 0.2 V vs Ag + /Ag, typically between 0.7V and 1.1V vs Ag + /Ag.
  • FIG. 2 illustrates the chronoamperogram obtained during the electrochemical dissolution of the anode in the electrolytic solution S1 at 40°C.
  • the anode is extracted from the electrolyte solution thus obtained, then the two wires are weighed.
  • the dissolution rate V d of the gold is also determined.
  • the faradic yield R f of gold dissolution is calculated assuming the formation of Au(I) during dissolution.
  • the yield is calculated by comparing the effective charge Q and the charge required to dissolve the amount of gold dissolved via the reaction: Au ⁇ Au(I) + e -
  • the electrolyte solution used is solution S1 (1-butyl-3-methylimidazolium thiocyanate [BMIM][SCN]).
  • the electrochemical dissolution test was carried out in air for a working temperature of 40°C.
  • the temperature is kept constant by a recirculating oil bath.
  • the solution is stirred at 600 revolutions/min (rpm) by a stirred bar during dissolution.
  • the electrochemical dissolution of the anode was carried out under potentiostatic control for 45 min, i.e. by applying a fixed potential, located beyond 0.2 V vs Ag + /Ag ( picture 3 ), for example 0.7 V vs Ag + /Ag.
  • the chronoamperogram confirms the electrochemical dissolution of the anode in the electrolyte solution.
  • the platinum counter-electrode is removed. It is weighed, observed by scanning electron microscopy (SEM) and its composition is analyzed by energy dispersive X-ray spectroscopy (EDX).
  • SEM scanning electron microscopy
  • EDX energy dispersive X-ray spectroscopy
  • the plate is covered by a deposit of gold is visible to the naked eye ( figure 4 ).
  • the SEM-EDX analysis confirms on the one hand that the part of the platinum counter-electrode not covered by the deposit does not contain any gold ( figure 5 ) and on the other hand that the deposit is in gold ( figure 6 ). No trace of palladium is observable.
  • the dissolution rate of gold is also determined.
  • Example 3 Study of the chemical dissolution of gold and palladium in different electrolytic solutions
  • the chemical dissolution tests were carried out in air for a working temperature of 80°C.
  • the temperature is kept constant by heating with a heating block.
  • the solution is stirred at 400 revolutions/min (rpm).
  • the results confirm the chemical dissolution of the gold wire and not the palladium wire.
  • concentration of thiocyanate must be greater than 0.1M to observe sufficient dissolution of the gold in 24 hours. Below this concentration, dissolution takes longer. Beyond 1M of thiocyanate, increasing the concentration does not lead to an improvement in the results.
  • Example 1 the surface of the palladium is covered with a yellow film after the test.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
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  • Metallurgy (AREA)
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EP22195178.3A 2021-09-16 2022-09-12 Verfahren zur selektiven rückgewinnung von gold durch grüne chemie aus einem element, das gold und ein platinoid enthält Pending EP4151763A1 (de)

Applications Claiming Priority (1)

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FR2109750A FR3126892A1 (fr) 2021-09-16 2021-09-16 Procede de recuperation selective de l’or par voie de chimie verte a partir d’un element contenant de l’or et un platinoide

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EP4151763A1 true EP4151763A1 (de) 2023-03-22

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090183997A1 (en) * 2008-01-17 2009-07-23 Phelps Dodge Corporation Method and apparatus for electrowinning copper using an atmospheric leach with ferrous/ferric anode reaction electrowinning
WO2015130607A1 (en) * 2014-02-25 2015-09-03 Advanced Technology Materials, Inc. Wet based formulations for the selective removal of noble metals
CN110404513A (zh) * 2018-04-28 2019-11-05 同济大学 聚苯胺酚用作贵金属吸附剂的应用
WO2021061184A1 (en) * 2019-09-23 2021-04-01 All Green Recycling, Inc. Systems and methods of efficiently recovering precious metals using an alkaline leach, ultrasound, and electrolysis
WO2021148758A1 (fr) * 2020-01-23 2021-07-29 Centre National De La Recherche Scientifique Procédé de récupération d'or et/ou d'un ou de platinoïdes présents dans une phase aqueuse acide

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090183997A1 (en) * 2008-01-17 2009-07-23 Phelps Dodge Corporation Method and apparatus for electrowinning copper using an atmospheric leach with ferrous/ferric anode reaction electrowinning
WO2015130607A1 (en) * 2014-02-25 2015-09-03 Advanced Technology Materials, Inc. Wet based formulations for the selective removal of noble metals
CN110404513A (zh) * 2018-04-28 2019-11-05 同济大学 聚苯胺酚用作贵金属吸附剂的应用
WO2021061184A1 (en) * 2019-09-23 2021-04-01 All Green Recycling, Inc. Systems and methods of efficiently recovering precious metals using an alkaline leach, ultrasound, and electrolysis
WO2021148758A1 (fr) * 2020-01-23 2021-07-29 Centre National De La Recherche Scientifique Procédé de récupération d'or et/ou d'un ou de platinoïdes présents dans une phase aqueuse acide

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
ABBOTT ET AL.: "Etectrocatalytic recovery of etementsfrom complex mixtures using deep eutectic solvents", GREEN CHEM, vol. 17, 2015, pages 2172 - 2179
JAYAKUMAR: "Electrochemical behavior of ruthénium (111), rhodium (II/) and palladium (II) in 1-butyl-3-methytimidozolium chloride ionic liquid ", ELECTROCHIMICA ACTA, vol. 54, 2009, pages 6747 - 6755, XP026546253, DOI: 10.1016/j.electacta.2009.06.043
POPESCU ET AL.: "Recovery of Silver and Gold From Electronic Waste by Electrodeposition in Ethaline lonic Liquid", REV. CHIM. (BUCHAREST, vol. 71, no. l, 2020, pages 122 - 132

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