EP3931363A1 - Method for extracting gold and/or silver and/or at least one platinum metal - Google Patents
Method for extracting gold and/or silver and/or at least one platinum metalInfo
- Publication number
- EP3931363A1 EP3931363A1 EP19724374.4A EP19724374A EP3931363A1 EP 3931363 A1 EP3931363 A1 EP 3931363A1 EP 19724374 A EP19724374 A EP 19724374A EP 3931363 A1 EP3931363 A1 EP 3931363A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- solution
- gold
- starting material
- hydroxyl radicals
- silver
- 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.)
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Classifications
-
- 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
- C22B11/08—Obtaining noble metals by cyaniding
-
- 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
- C22B3/16—Extraction of metal compounds from ores or concentrates by wet processes by leaching in organic solutions
-
- 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
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
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- 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 to a method for extracting gold and / or silver and / or at least one platinum metal from at least one starting material.
- Gold, silver and platinum metals are essential raw materials. They can be recovered from valuable waste, for example as part of catalyst materials or from electronic devices, pyrometallurgical or hydrometallurgical. The pyrometallurgical recovery takes place by removing the scrap metals
- metals to be recovered brought into an aqueous solution by complex formation.
- An example of such a process is alkaline cyanide leaching for gold mining. This process is carried out at very high pH values, i.e. using aggressive alkalis.
- the complexing agent used, cyanide is very toxic, making this process too dangerous
- the pH of a cyanide-containing solution can be increased by the absorption of carbon dioxide from the ambient air
- Platinum metals are understood to mean the light platinum metals ruthenium, rhodium and palladium and the heavy platinum metals iridium and platinum. Be under scrap metal
- the at least one starting material which contains gold and / or silver and / or at least one platinum metal, is introduced into an aqueous solution which contains at least one nitrile.
- the nitrile is selected in particular from the group consisting of acetonitrile, isobutyronitrile and propionitrile, with acetonitrile being particularly preferred. Be in the aqueous solution
- hydroxyl radicals By reacting the hydroxyl radicals with the nitrile, just as many cyanides (ions or radicals) can be generated in situ as are necessary to bring the metal to be extracted into solution.
- the hydroxyl radicals can act on the metal as
- Oxidizing agents act. This means that it is not necessary to work with large excesses of cyanides, nor is it necessary to use large amounts of strong alkalis.
- the hydroxyl radicals are generated by introducing ozone into the solution. This can react with water to form oxygen and hydroxyl radicals, the reaction being carried out in particular photocatalytically.
- the ozone required for this can be generated, for example, by corona discharges or electrochemically.
- the solution preferably contains 0.1 mol per liter to 1.0 mol per liter of at least one alkali metal hydroxide, in particular sodium hydroxide or potassium hydroxide. Due to the targeted formation of cyanides (ions or radicals) and the oxidizing effect of the hydroxyl radicals, this amount of alkali hydroxide is sufficient to effectively prevent the formation of gaseous hydrogen cyanide. Furthermore, in this embodiment of the method it is preferred that the ozone is introduced into the solution through a porous diffuser below the starting material. In this way it flows around the starting material and the formation of hydroxyl radicals takes place near the surface of the
- the solution flows in the same direction as the starting material as the ozone. This way, fresh solution is enriched with ozone before it
- the hydroxyl radicals are generated in the solution by a Fenton reaction.
- the Fenton reaction is an iron salt catalyzed reaction of hydrogen peroxide in acidic solution.
- the solution can in particular contain Fenton's reagent, a sulfuric acid mixture of hydrogen peroxide and an iron salt.
- Iron (II) sulfate is particularly suitable as the iron salt.
- Electro-Fenton reaction requires a strongly acidic solution in order to neutralize the hydroxyl anions formed
- a combination of the Electro-Fenton reaction with a Photo-Fenton reaction can also generate the hydroxyl radicals in a weakly acidic solution, for which the solution preferably contains formic acid. This reduces the risk of the formation of gaseous hydrocyanic acid due to the release of cyanide ions from cyanometallic complexes.
- the solution contains at least 0.1 mol per liter of the at least one nitrile in order to provide a sufficiently large source for the generation of cyanides (ions or radicals).
- the solution contains at least one substance which is selected from the group consisting of alcohols, surfactants and Activated carbon.
- alcohols the short-chain alcohols methanol, ethanol and isopropanol are preferred.
- surfactants the alcohols bring about improved wetting of the at least one starting material by the aqueous solution.
- the activated carbon has a large surface on which the formation of hydroxyl radicals can take place.
- the solution is irradiated with UV light.
- UV light preferably has a wavelength of less than 310 nm.
- the wavelength of the UV light used is preferably less than 580 nm.
- Figure 1 shows schematically a reactor in which a method according to an embodiment of the invention takes place.
- FIG. 2 shows schematically another reactor in which a method according to another exemplary embodiment of the invention takes place.
- Figure 1 shows how in an embodiment of the invention from a
- Starting material 10 which in the present case is a printed circuit board, gold can be detached from a nickel substrate. This is for this
- aqueous solution 20 which is stored in a reactor 21. Fresh solution is continuously fed in through an inlet opening 22, which is arranged below the starting material 10 on the wall of the reactor 21, while solution enriched with cyano complexes of gold is passed through a Above the starting material 10 in the wall of the reactor 21 arranged outlet opening 23 is derived.
- the aqueous solution 20 contains im
- Ozone 30 is introduced into the reactor 21 through a porous diffuser 31 which is arranged in the reactor 21 below the starting material 10 and below the inlet opening 22. It mixes with the fresh solution 20, which is passed through the inlet opening 22 into reactor 21, and flows around the starting material 10.
- the reactor 21 consists of a transparent material and is illuminated from the outside by means of a UV lamp 40 with light with a wavelength of less than 310 nm irradiated. According to formula 1, the ozone photocatalytically forms oxygen and hydroxyl radicals with water molecules: (Formula 1)
- a mixture 32 of unreacted ozone and the oxygen formed leaves the reactor 21 through a gas outlet 24 on its top.
- hydroxyl radicals react with the acetonitrile to form cyanogen radicals to form methanol. These oxidize metallic gold
- hydroxyl radicals according to formula 3 can themselves oxidize gold to gold (l) hydroxide on the metal surface. This is highly reactive and reacts with the acetonitrile to form methanol to gold (l) cyanide:
- the gold (l) cyanide goes into solution and leaves the reactor through the
- a reactor 21 is used, as shown in FIG. This differs from the reactor according to FIG. 1 in that the porous diffuser 31 for introducing ozone 30 and the gas outlet opening 24 are dispensed with. Instead, an electrical energy source 40 is provided, which is connected to two electrodes 51, 52 which protrude below the starting material 10 into the reactor 21.
- the aqueous solution 20 additionally contains iron (II) sulfate and before it is introduced through the inlet opening 22 through a line (not shown) it is continuously enriched with hydrogen peroxide by formation on a cathode. Instead of 0.5 mol / l
- the Photo-Fenton reaction causes both a regeneration of the iron (II) cations oxidized in the Electro-Fenton reaction by reduction and a neutralization of the hydroxyl anions generated there, so that the pH of the solution 20 does not change.
- the hydroxyl radicals generated in the two Fenton reactions then react as in the first embodiment the process according to formulas 2 and 3 and bring gold in the form of gold (l) cyanide in solution. Removing the cyanide with gold (l)
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- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
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- Physical Water Treatments (AREA)
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Abstract
The invention relates to a method for extracting gold and/or silver and/or at least one platinum metal. At least one starting material (10) which contains gold, silver and/or platinum metal is introduced into an aqueous solution (20) that contains at least one nitrile. Hydroxyl radicals are produced in the aqueous solution.
Description
Beschreibung description
Titel title
Verfahren zur Gewinnung von Gold und/oder Silber und/oder mindestens einem Process for the extraction of gold and / or silver and / or at least one
Platinmetall Platinum metal
Die vorliegende Erfindung betrifft ein Verfahren zur Gewinnung von Gold und/oder Silber und/oder mindestens einem Platinmetall aus mindestens einem Ausgangsmaterial. The present invention relates to a method for extracting gold and / or silver and / or at least one platinum metal from at least one starting material.
Stand der Technik State of the art
Gold, Silber und Platinmetalle sind essentielle Rohstoffe. Ihre Rückgewinnung aus Wertstoffabfall, beispielsweise als Teil von Katalysatormaterialien oder von elektronischen Geräten kann pyrometallurgisch oder hydrometallurgisch erfolgen. Die pyrometallurgische Rückgewinnung erfolgt, indem die Altmetalle Gold, silver and platinum metals are essential raw materials. They can be recovered from valuable waste, for example as part of catalyst materials or from electronic devices, pyrometallurgical or hydrometallurgical. The pyrometallurgical recovery takes place by removing the scrap metals
geschmolzen und dann durch verschiedene Verfahren aufbereitet werden. Dies ist allerdings sehr energieintensiv und mit dem Entstehen toxischer Emissionen verbunden. Bei der hydrometallurgischen Rückgewinnung werden die melted and then processed by various processes. However, this is very energy-intensive and associated with the creation of toxic emissions. In hydrometallurgical recovery, the
zurückzugewinnenden Metalle durch Komplexbildung in eine wässrige Lösung gebracht. Ein Beispiel für ein solches Verfahren ist das alkalische Cyanidlaugen zur Goldgewinnung. Dieses Verfahren wird bei sehr hohen pH-Werten, also unter Verwendung aggressiver Laugen, durchgeführt. Der verwendete Komplexbildner Cyanid ist sehr toxisch, sodass auch dieses Verfahren zu gefährlichen metals to be recovered brought into an aqueous solution by complex formation. An example of such a process is alkaline cyanide leaching for gold mining. This process is carried out at very high pH values, i.e. using aggressive alkalis. The complexing agent used, cyanide, is very toxic, making this process too dangerous
Emissionen führen kann. Insbesondere kann der pH-Wert einer cyanidhaltigen Lösung durch Aufnahme von Kohlendioxid aus der Umgebungsluft Emissions. In particular, the pH of a cyanide-containing solution can be increased by the absorption of carbon dioxide from the ambient air
beispielsweise so stark ansteigen, dass Blausäure aus der Lösung ausgast. for example increase so much that hydrogen cyanide is outgassed from the solution.
Offenbarung der Erfindung
Das Verfahren dient zur Gewinnung von Gold und/oder Silber und/oder mindestens einem Platinmetall aus mindestens einem Ausgangsmaterial, insbesondere aus einem Wertstoffabfall oder aus natürlich vorkommenden Erzen. Unter Platinmetallen (platinum group metals; PGM) werden dabei die leichten Platinmetalle Ruthenium, Rhodium und Palladium und die schweren Platinmetalle Iridium und Platin verstanden. Unter Altmetallen werden Disclosure of the invention The method is used to extract gold and / or silver and / or at least one platinum metal from at least one starting material, in particular from valuable waste or from naturally occurring ores. Platinum metals (platinum group metals; PGM) are understood to mean the light platinum metals ruthenium, rhodium and palladium and the heavy platinum metals iridium and platinum. Be under scrap metal
verarbeitete Metalle jeglicher Form verstanden, beispielsweise Metalle als Teil von Katalysatoren oder Metalle als Teil von elektronischen Geräten. Das mindestens eine Ausgangsmaterial, welches Gold und/oder Silber und/oder mindestens einem Platinmetall enthält, wird in eine wässrige Lösung eingebracht, welche mindestens ein Nitril enthält. Das Nitril ist insbesondere ausgewählt aus der Gruppe, die aus Acetonitril, Isobutyronitril und Propionitril besteht, wobei Acetonitril besonders bevorzugt ist. In der wässrigen Lösung werden Processed metals of any form understood, for example metals as part of catalysts or metals as part of electronic devices. The at least one starting material, which contains gold and / or silver and / or at least one platinum metal, is introduced into an aqueous solution which contains at least one nitrile. The nitrile is selected in particular from the group consisting of acetonitrile, isobutyronitrile and propionitrile, with acetonitrile being particularly preferred. Be in the aqueous solution
Hydroxylradikale erzeugt. Durch Reaktion der Hydroxylradikale mit dem Nitril können in situ gerade so viele Cyanide (Ionen oder Radikale) erzeugt werden, wie erforderlich sind, um das zu gewinnende Metall in Lösung zu bringen. Generates hydroxyl radicals. By reacting the hydroxyl radicals with the nitrile, just as many cyanides (ions or radicals) can be generated in situ as are necessary to bring the metal to be extracted into solution.
Gleichzeitig können die Hydroxylradikale gegenüber dem Metall als At the same time, the hydroxyl radicals can act on the metal as
Oxidationsmittel fungieren. Hierdurch muss weder mit großen Überschüssen an Cyaniden gearbeitet werden, noch ist die Verwendung großer Mengen starker Laugen erforderlich. Oxidizing agents act. This means that it is not necessary to work with large excesses of cyanides, nor is it necessary to use large amounts of strong alkalis.
In einer Ausführungsform des Verfahrens werden die Hydroxylradikale erzeugt, indem Ozon in die Lösung eingeleitet wird. Dieses kann mit Wasser unter Bildung von Sauerstoff und Hydroxylradikalen reagieren, wobei die Reaktion insbesondere photokatalytisch durchgeführt wird. Das hierfür benötigte Ozon kann beispielsweise durch Koronaentladungen oder elektrochemisch erzeugt werden. In one embodiment of the method, the hydroxyl radicals are generated by introducing ozone into the solution. This can react with water to form oxygen and hydroxyl radicals, the reaction being carried out in particular photocatalytically. The ozone required for this can be generated, for example, by corona discharges or electrochemically.
Die Lösung enthält in dieser Ausführungsform des Verfahrens vorzugsweise 0,1 Mol pro Liter bis 1,0 Mol pro Liter mindestens eines Alkalimetallhydroxids, insbesondere Natriumhydroxids oder Kaliumhydroxids. Aufgrund der gezielten Bildung von Cyaniden (Ionen oder Radikale) und der oxidierenden Wirkung der Hydroxylradikale ist diese Menge des Alkalihydroxids ausreichend, um eine Bildung von gasförmiger Blausäure wirksam zu unterbinden.
Weiterhin ist es in dieser Ausführungsform des Verfahrens bevorzugt, dass das Ozon durch einen porösen Diffusor unterhalb des Ausgangsmaterials in die Lösung eingeleitet wird. Auf diese Weise umströmt es das Ausgangsmaterial und die Bildung der Hydroxylradikale erfolgt in der Nähe der Oberfläche des In this embodiment of the method, the solution preferably contains 0.1 mol per liter to 1.0 mol per liter of at least one alkali metal hydroxide, in particular sodium hydroxide or potassium hydroxide. Due to the targeted formation of cyanides (ions or radicals) and the oxidizing effect of the hydroxyl radicals, this amount of alkali hydroxide is sufficient to effectively prevent the formation of gaseous hydrogen cyanide. Furthermore, in this embodiment of the method it is preferred that the ozone is introduced into the solution through a porous diffuser below the starting material. In this way it flows around the starting material and the formation of hydroxyl radicals takes place near the surface of the
Ausgangsmaterials. Starting material.
In dieser Ausführungsform ist es weiterhin bevorzugt, dass die Lösung in dieselbe Richtung wie das Ausgangsmaterial strömt wie das Ozon. Auf diese Weise wird frische Lösung mit Ozon angereichert, bevor sie das In this embodiment it is further preferred that the solution flows in the same direction as the starting material as the ozone. This way, fresh solution is enriched with ozone before it
Ausgangsmaterial kontaktiert und kann nach Kontakt mit dem Ausgangsmaterial zusammen mit darin gelösten Metallcyanokomplexen aus einem für das Contacted starting material and after contact with the starting material together with metal cyanocomplexes dissolved therein from a for the
Verfahren verwendeten Reaktor herausgeleitet werden. Process used reactor are led out.
In einer anderen Ausführungsform des Verfahrens werden die Hydroxylradikale durch eine Fenton- Reaktion in der Lösung erzeugt. Die Fenton- Reaktion ist eine durch ein Eisensalz katalysierte Reaktion von Wasserstoffperoxid in saurer Lösung. Hierzu kann die Lösung insbesondere Fentons Reagenz enthalten, eine schwefelsaure Mischung aus Wasserstoffperoxid und einem Eisensalz. Als Eisensalz ist insbesondere Eisen(ll)sulfat geeignet. In another embodiment of the method, the hydroxyl radicals are generated in the solution by a Fenton reaction. The Fenton reaction is an iron salt catalyzed reaction of hydrogen peroxide in acidic solution. For this purpose, the solution can in particular contain Fenton's reagent, a sulfuric acid mixture of hydrogen peroxide and an iron salt. Iron (II) sulfate is particularly suitable as the iron salt.
Während eine reine Elektro- Fenton- Reaktion eine stark saure Lösung erfordert, um dabei gebildete Hydroxylanionen zu neutralisieren, kann beispielsweise durch eine Kombination der Elektro- Fenton- Reaktion mit einer Photo- Fenton- Reaktion die Erzeugung der Hydroxylradikale auch in einer schwachsauren Lösung erfolgen, wozu die Lösung vorzugsweise Ameisensäure enthält. Hierdurch wird das Risiko der Bildung von gasförmiger Blausäure durch Freisetzung von Cyanidionen aus Cyanometallkomplexen verringert. While a pure Electro-Fenton reaction requires a strongly acidic solution in order to neutralize the hydroxyl anions formed, for example, a combination of the Electro-Fenton reaction with a Photo-Fenton reaction can also generate the hydroxyl radicals in a weakly acidic solution, for which the solution preferably contains formic acid. This reduces the risk of the formation of gaseous hydrocyanic acid due to the release of cyanide ions from cyanometallic complexes.
In allen Ausführungsformen des Verfahrens ist es bevorzugt, dass die Lösung mindestens 0,1 Mol pro Liter des mindestens einen Nitrils enthält, um eine ausreichend große Quelle für die Erzeugung von Cyaniden (Ionen oder Radikale) zur Verfügung zu stellen. In all embodiments of the method, it is preferred that the solution contains at least 0.1 mol per liter of the at least one nitrile in order to provide a sufficiently large source for the generation of cyanides (ions or radicals).
Weiterhin ist es bevorzugt, dass die Lösung zumindest eine Substanz enthält, die ausgewählt ist, aus der Gruppe bestehend aus Alkoholen, Tensiden und
Aktivkohle. Unter den Alkoholen sind dabei die kurzkettigen Alkohole Methanol, Ethanol und Isopropanol bevorzugt. Ebenso wie die Tenside bewirken die Alkohole eine verbesserte Benetzung des mindestens einen Ausgangsmaterials durch die wässrige Lösung. Die Aktivkohle weist eine hohe Oberfläche auf, an welcher die Bildung von Hydroxylradikalen ablaufen kann. Furthermore, it is preferred that the solution contains at least one substance which is selected from the group consisting of alcohols, surfactants and Activated carbon. Among the alcohols, the short-chain alcohols methanol, ethanol and isopropanol are preferred. Just like the surfactants, the alcohols bring about improved wetting of the at least one starting material by the aqueous solution. The activated carbon has a large surface on which the formation of hydroxyl radicals can take place.
Weiterhin ist es bevorzugt, dass die Lösung mit UV-Licht bestrahlt wird. Bei der Bildung von Hydroxylradikalen durch Einleitung von Ozon in die Lösung kann hierdurch eine Photokatalyse der Reaktion erreicht werden. Hierzu hat das UV- Licht bevorzugt eine Wellenlänge von weniger als 310 nm. Bei einer Erzeugung der Hydroxylradikale durch eine Fenton- Reaktion ermöglicht die Bestrahlung das Ablaufen einer Photo- Fenton- Reaktion. Hierzu beträgt die Wellenlänge des verwendeten UV-Lichts vorzugsweise weniger als 580 nm. It is also preferred that the solution is irradiated with UV light. With the formation of hydroxyl radicals through the introduction of ozone into the solution, a photocatalysis of the reaction can be achieved. For this purpose, the UV light preferably has a wavelength of less than 310 nm. When the hydroxyl radicals are generated by a Fenton reaction, the irradiation enables a photo Fenton reaction to take place. For this purpose, the wavelength of the UV light used is preferably less than 580 nm.
Kurze Beschreibung der Zeichnungen Brief description of the drawings
Ausführungsbeispiele der Erfindung sind in den Zeichnungen dargestellt und werden in der nachfolgenden Beschreibung näher erläutert. Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description.
Figur 1 zeigt schematisch einen Reaktor, in dem ein Verfahren gemäß einem Ausführungsbeispiel der Erfindung abläuft. Figure 1 shows schematically a reactor in which a method according to an embodiment of the invention takes place.
Figur 2 zeigt schematisch einen anderen Reaktor, in dem ein Verfahren gemäß einem anderen Ausführungsbeispiel der Erfindung abläuft. FIG. 2 shows schematically another reactor in which a method according to another exemplary embodiment of the invention takes place.
Ausführungsbeispiele der Erfindung Embodiments of the invention
Figur 1 zeigt, wie in einem Ausführungsbeispiel der Erfindung aus einem Figure 1 shows how in an embodiment of the invention from a
Ausgangsmaterial 10, bei dem es sich vorliegend um eine Leiterplatte handelt, Gold von einem Nickelsubstrat gelöst werden kann. Hierzu ist das Starting material 10, which in the present case is a printed circuit board, gold can be detached from a nickel substrate. This is for this
Ausgangsmaterial 10 in einem Rahmen 11 befestigt. Dieser wird von einer wässrigen Lösung 20 bedeckt, die in einem Reaktor 21 bevorratet ist. Durch eine Einlassöffnung 22, welche unterhalb des Ausgangsmaterials 10 an der Wand des Reaktors 21 angeordnet ist, wird kontinuierlich frische Lösung herangeführt, während mit Cyanokomplexen des Goldes angereicherte Lösung durch eine
oberhalb des Ausgangsmaterials 10 in der Wand des Reaktors 21 angeordnete Auslassöffnung 23 abgeleitet wird. Die wässrige Lösung 20 enthält im Starting material 10 fastened in a frame 11. This is covered by an aqueous solution 20 which is stored in a reactor 21. Fresh solution is continuously fed in through an inlet opening 22, which is arranged below the starting material 10 on the wall of the reactor 21, while solution enriched with cyano complexes of gold is passed through a Above the starting material 10 in the wall of the reactor 21 arranged outlet opening 23 is derived. The aqueous solution 20 contains im
vorliegenden Ausführungsbeispiel 0,5 mol/l Acetonitril und 0,5 mol/l present embodiment 0.5 mol / l acetonitrile and 0.5 mol / l
Natriumhydroxid. Weiterhin enthält sie Methanol, Tenside und Aktivkohle. Ozon 30 wird durch einen porösen Diffusor 31, der im Reaktor 21 unterhalb des Ausgangsmaterials 10 und unterhalb der Einlassöffnung 22 angeordnet ist, in den Reaktor 21 eingeleitet. Es vermischt sich mit der frischen Lösung 20, die durch die Einlassöffnung 22 in Reaktor 21 geleitet wird, und umströmt das Ausgangsmaterial 10. Der Reaktor 21 besteht aus einem transparenten Material und wird von außen mittels einer UV-Lampe 40 mit Licht mit einer Wellenlänge von weniger als 310 nm bestrahlt. Dabei bildet das Ozon gemäß Formel 1 mit Wassermolekülen photokatalytisch Sauerstoff- und Hydroxylradikale:
(Formel 1) Sodium hydroxide. It also contains methanol, surfactants and activated carbon. Ozone 30 is introduced into the reactor 21 through a porous diffuser 31 which is arranged in the reactor 21 below the starting material 10 and below the inlet opening 22. It mixes with the fresh solution 20, which is passed through the inlet opening 22 into reactor 21, and flows around the starting material 10. The reactor 21 consists of a transparent material and is illuminated from the outside by means of a UV lamp 40 with light with a wavelength of less than 310 nm irradiated. According to formula 1, the ozone photocatalytically forms oxygen and hydroxyl radicals with water molecules: (Formula 1)
Ein Gemisch 32 aus nicht abreagiertem Ozon und dem gebildeten Sauerstoff verlässt den Reaktor 21 durch einen Gasauslass 24 an seiner Oberseite. A mixture 32 of unreacted ozone and the oxygen formed leaves the reactor 21 through a gas outlet 24 on its top.
Die Hydroxylradikale gehen in der Lösung 20 im Wesentlichen zwei Reaktionen ein: The hydroxyl radicals essentially enter into two reactions in solution 20:
Gemäß Formel 2 reagieren Hydroxylradikale mit dem Acetonitril unter Bildung von Methanol zu Cyanoradikalen. Diese oxidieren metallisches Gold zu According to formula 2, hydroxyl radicals react with the acetonitrile to form cyanogen radicals to form methanol. These oxidize metallic gold
Gold(l)cyanid: Gold (l) cyanide:
OH’ + CH3CN + Au - > CN’ + Au - > AuCN (Formel 2) OH '+ CH 3 CN + Au ->CN' + Au -> AuCN (Formula 2)
- CH3OH - CH 3 OH
Weiterhin können die Hydroxylradikale gemäß Formel 3 an der Metalloberfläche selbst Gold zu Gold(l)hydroxid oxidieren. Dieses ist hoch reaktiv und reagiert mit dem Acetonitril unter Bildung von Methanol zu Gold(l)cyanid: Furthermore, the hydroxyl radicals according to formula 3 can themselves oxidize gold to gold (l) hydroxide on the metal surface. This is highly reactive and reacts with the acetonitrile to form methanol to gold (l) cyanide:
OH’ + CH3CN + Au - > AuOH + CH3CN > AuCN (Formel 3) OH '+ CH 3 CN + Au -> AuOH + CH 3 CN> AuCN (Formula 3)
- CH3OH - CH 3 OH
Das Gold(l)cyanid geht in Lösung und verlässt den Reaktor durch die The gold (l) cyanide goes into solution and leaves the reactor through the
Auslassöffnung 23. Anschließend kann das Gold mittels aus der Cyanidlaugerei
bekannter Methoden aus der Lösung ausgefällt werden und diese anschließend durch die Einlassöffnung 22 wieder in den Reaktor 21 eingeleitet werden. Auf diese Weise können im vorliegenden Ausführungsbeispiel 0,5 bis 2 Milligramm Gold pro Quadratzentimeter Oberfläche des Ausgangsmaterials 10 und pro Stunde gewonnen werden. Sobald das gesamte Gold abgetragen wurde, geht kein weiteres Metall in Lösung, da Nickel unter alkalischen Bedingungen eine inerte Schutzschicht aus Nickelhydroxid bildet. Outlet opening 23. The gold can then be extracted from the cyanide leaching known methods are precipitated from the solution and these are then introduced back into the reactor 21 through the inlet opening 22. In this way, in the present exemplary embodiment, 0.5 to 2 milligrams of gold can be obtained per square centimeter of surface of the starting material 10 and per hour. Once all of the gold has been removed, no more metal goes into solution, as nickel forms an inert protective layer of nickel hydroxide under alkaline conditions.
In einem zweiten Ausführungsbeispiel des Verfahrens wird ein Reaktor 21 verwendet, wie er in Figur 2 dargestellt ist. Dieser unterscheidet sich von dem Reaktor gemäß Figur 1 dadurch, dass auf dem porösen Diffusor 31 zum Einleiten von Ozon 30 und auf die Gasauslassöffnung 24 verzichtet wird. Stattdessen ist eine elektrische Energiequelle 40 vorgesehen, die mit zwei Elektroden 51, 52 verbunden ist, die unterhalb des Ausgangsmaterials 10 in den Reaktor 21 hineinragen. Die wässrige Lösung 20 enthält in diesem Ausführungsbeispiel zusätzlich Eisen(ll)sulfat und sie wird vor dem Einleiten durch die Einlassöffnung 22 durch eine nicht dargestellte Leitung kontinuierlich durch Bildung an einer Kathode mit Wasserstoffperoxid angereichert. Anstelle von 0,5 mol/l In a second exemplary embodiment of the method, a reactor 21 is used, as shown in FIG. This differs from the reactor according to FIG. 1 in that the porous diffuser 31 for introducing ozone 30 and the gas outlet opening 24 are dispensed with. Instead, an electrical energy source 40 is provided, which is connected to two electrodes 51, 52 which protrude below the starting material 10 into the reactor 21. In this exemplary embodiment, the aqueous solution 20 additionally contains iron (II) sulfate and before it is introduced through the inlet opening 22 through a line (not shown) it is continuously enriched with hydrogen peroxide by formation on a cathode. Instead of 0.5 mol / l
Natriumhydroxid enthält sie 0,5 mol/l Ameisensäure. Durch Anliegen einer elektrischen Spannung zwischen den Elektroden 51, 52 läuft in der Lösung 20 innerhalb des Reaktors 21 eine Elektro- Fenton- Reaktion gemäß Formel 4 ab: Sodium hydroxide contains 0.5 mol / l formic acid. When an electrical voltage is applied between the electrodes 51, 52, an Electro-Fenton reaction according to formula 4 takes place in the solution 20 within the reactor 21:
Fe2+ + H202 - > Fe3+ + OH~ + OH * (Formel 4) Fe 2+ + H 2 0 2 -> Fe 3+ + OH ~ + OH * (formula 4)
Die Bestrahlung mittels der UV-Lampe 40 erfolgt bei einer Wellenlänge von weniger als 580 nm. Hierdurch läuft in der Lösung 20 weiterhin eine Photo- Fenton- Reaktion gemäß Formel 5 ab:
(Formel 5) The irradiation by means of the UV lamp 40 takes place at a wavelength of less than 580 nm. As a result, a Photo-Fenton reaction continues in the solution 20 according to formula 5: (Formula 5)
Die Photo- Fenton- Reaktion bewirkt sowohl eine Regenerierung der in der Elektro- Fenton- Reaktion oxidierten Eisen(ll)- Kationen durch Reduktion als auch eine Neutralisierung der dort erzeugten Hydroxylanionen, sodass sich der pH- Wert der Lösung 20 nicht ändert. Die in den beiden Fenton- Reaktionen erzeugten Hydroxyl radikale reagieren dann wie im ersten Ausführungsbeispiel
des Verfahrens gemäß den Formeln 2 und 3 weiter und bringen Gold in Form von Gold(l)cyanid in Lösung. Das Entnehmen der mit Gold(l)cyanid The Photo-Fenton reaction causes both a regeneration of the iron (II) cations oxidized in the Electro-Fenton reaction by reduction and a neutralization of the hydroxyl anions generated there, so that the pH of the solution 20 does not change. The hydroxyl radicals generated in the two Fenton reactions then react as in the first embodiment the process according to formulas 2 and 3 and bring gold in the form of gold (l) cyanide in solution. Removing the cyanide with gold (l)
angereicherten Lösung 20 aus dem Reaktor 21 und das Ausfällen von metallischem Gold erfolgt in derselben Weise wie im ersten Ausführungsbeispiel.
enriched solution 20 from the reactor 21 and the precipitation of metallic gold takes place in the same way as in the first embodiment.
Claims
1. Verfahren zur Gewinnung von Gold und/oder Silber und/oder mindestens einem Platinmetall, worin mindestens ein Ausgangsmaterial (10), welches Gold und/oder Silber und/oder mindestens ein Platinmetall enthält in eine wässrige Lösung (20) eingebracht wird, welche mindestens ein Nitril enthält und wobei in der wässrigen Lösung Hydroxylradikale erzeugt werden. 1. A method for the extraction of gold and / or silver and / or at least one platinum metal, wherein at least one starting material (10) which contains gold and / or silver and / or at least one platinum metal is introduced into an aqueous solution (20) which contains at least one nitrile and wherein hydroxyl radicals are generated in the aqueous solution.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die 2. The method according to claim 1, characterized in that the
Hydroxylradikale erzeugt werden, indem Ozon (30) in die Lösung (20) eingeleitet wird. Hydroxyl radicals are generated by introducing ozone (30) into the solution (20).
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass die Lösung (20) 0,1 mol/l bis 1,0 mol/l mindestens eines Alkalihydroxids enthält. 3. The method according to claim 2, characterized in that the solution (20) contains 0.1 mol / l to 1.0 mol / l of at least one alkali hydroxide.
4. Verfahren nach Anspruch 2 oder 3, dadurch gekennzeichnet, dass das Ozon (30) durch einen porösen Diffusor (31) unterhalb des Ausgangsmaterials (10) in die Lösung (20) eingeleitet wird. 4. The method according to claim 2 or 3, characterized in that the ozone (30) is introduced into the solution (20) through a porous diffuser (31) below the starting material (10).
5. Verfahren nach einem der Ansprüche 2 bis 4, dadurch gekennzeichnet, dass die Lösung (20) in dieselbe Richtung über das Ausgangsmaterial strömt wie das Ozon (30). 5. The method according to any one of claims 2 to 4, characterized in that the solution (20) flows in the same direction over the starting material as the ozone (30).
6. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die 6. The method according to claim 1, characterized in that the
Hydroxylradikale durch eine Fenton- Reaktion in der Lösung (20) erzeugt werden. Hydroxyl radicals are generated in the solution (20) by a Fenton reaction.
7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, dass die Lösung (20) Ameisensäure enthält. 7. The method according to claim 6, characterized in that the solution (20) contains formic acid.
8. Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass die Lösung (20) mindestens 0,1 mol/l des mindestens einen Nitrils enthält.
8. The method according to any one of claims 1 to 7, characterized in that the solution (20) contains at least 0.1 mol / l of the at least one nitrile.
9. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass die Lösung (20) zumindest eine Substanz enthält, die ausgewählt ist aus der Gruppe, bestehend aus Alkoholen, Tensiden und Aktivkohle. 9. The method according to any one of claims 1 to 8, characterized in that the solution (20) contains at least one substance which is selected from the group consisting of alcohols, surfactants and activated carbon.
10. Verfahren nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass die Lösung (20) mit UV-Licht bestrahlt wird.
10. The method according to any one of claims 1 to 9, characterized in that the solution (20) is irradiated with UV light.
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