EP0602426B1 - Electrolytic process for obtaining high purity platinum from platinum alloys - Google Patents

Electrolytic process for obtaining high purity platinum from platinum alloys Download PDF

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Publication number
EP0602426B1
EP0602426B1 EP93118979A EP93118979A EP0602426B1 EP 0602426 B1 EP0602426 B1 EP 0602426B1 EP 93118979 A EP93118979 A EP 93118979A EP 93118979 A EP93118979 A EP 93118979A EP 0602426 B1 EP0602426 B1 EP 0602426B1
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Prior art keywords
platinum
process according
ppm
hydrochloric acid
anode
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German (de)
French (fr)
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EP0602426A1 (en
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Sigrid Dr. Herrmann
Uwe Dr.-Ing. Landau
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Schott AG
Carl Zeiss AG
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Carl Zeiss AG
Schott Glaswerke AG
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    • 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

Definitions

  • the present invention relates to an electrolytic process for the production of high purity platinum from concentrated hydrochloric acid solutions of platinum alloys with Rh, Ir and / or Pd with simultaneous depletion of other noble metal and base metal impurities.
  • Platinum alloys are widely used in industry as device platinum, for thermocouples, as catalysts for ammonia oxidation and in organic chemistry, for exhaust gas catalysts, in dental technology and many other areas. Depending on the chemical and other production processes, these alloys are given to the precious metal processing plants as platinum alloy scrap after a certain time, where they are chemically separated and refined.
  • the electrolysis cell is equipped with a cation exchange membrane, the advantages of which are not apparent, however, since platinum and palladium can also be separated without the cation exchange membrane in the concentration ratio and the voltage range described.
  • this method has the same disadvantage as all other methods that only a maximum concentration of ⁇ 100g / l can be used.
  • the invention is therefore based on the object of providing a process for the production of platinum of high purity, in which platinum from its alloying elements and impurities is obtained with small apparatus, within a short time, with minimal losses, with little labor and without the addition of expensive chemicals can be separated in a purity of 99.95%.
  • the invention therefore relates to an electrolytic process for the production of high purity platinum from concentrated hydrochloric acid solutions of platinum alloys with Rh, Ir and / or Pd with simultaneous depletion of other noble metal and base metal impurities.
  • the process according to the invention is characterized in that the cleaning process takes place in an electrolysis cell, which is divided by a cation exchange membrane, under potentiostatic or voltage-controlled conditions of 8 V to 16 V and a current density of 12.5 to 37.5 A / dm 2 and the deposited platinum alloy metals are worked up.
  • the hydrochloric acid solutions of platinum alloys have a content of 50 to 700 g / l and total impurities of ⁇ 5000 ppm.
  • Solutions of platinum alloys with a content of 500 to 700 g / l are preferably used in the process according to the invention.
  • the concentrated solutions of the platinum alloys used for the process according to the invention contain impurities in the elements Au and / or Ag, Cu, Fe, Co, Ni, Sb, As, Pb, Cd, Al, Mn, Mo, Si, Zn, Sn, Zr, W, Ti, Cr on.
  • Hydrochloric acid platinum metal solutions preferably hexachloroplatinic acid
  • 6 to 8 N hydrochloric acid preferably 6 N hydrochloric acid
  • the anode is made of platinum metal, while the cathode is made of platinum metal, titanium or graphite.
  • a Teflon membrane (Nafion® membrane) is used as the preferred cation exchange membrane loaded with sulfonic acid groups.
  • the method according to the invention preferably works under potentiostatic or voltage-controlled conditions of 11.5 V to 12 V and a current density of 22.5 to 35 A / dm 2 .
  • the base metal and noble metal impurities are deposited on the cathode with a small proportion of platinum metals. Surprisingly, it was found that the alloy constituents Ir, Rh and / or Pd deposit together with small amounts of the platinum on the anode.
  • the precipitate on the cathode is mechanically removed from it and processed separately.
  • the Ir, Rh and / or Pd deposited on the anode is refined after being transferred to the solution by renewed electrolysis.
  • the chlorine gas developing in the process according to the invention is removed by known methods.
  • the metallic platinum can be recovered electrolytically or chemically by known methods.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

The electrolytic process for obtaining platinum of high purity from concentrated hydrochloric acid solutions of a platinum alloy containing Rh, Ir and/or Pd proceeds with simultaneous depletion of noble and base metal impurities from the solution. This electrolysis process takes place in an electrolysis cell having an anode and cathode and subdivided by a teflon cation exchanger membrane under potentiostatic or, voltage-controlled conditions with a potential applied across the anode and cathode of 8 V to 16 V, preferably 11.5 to 12 V, at a current density of 12.5 to 37.5 A/dm2, preferably 22.5 to 35 A/dm2, to form a purified platinum-containing solution from which the high purity platinum can be obtained and also platinum alloy metal component deposits on the anode and cathode. The concentrated hydrochloric acid solution of the platinum alloy can have a platinum alloy content of 50 to 700 g/l and total metal impurities of not greater than 5000 ppm.

Description

Die vorliegende Erfindung betrifft ein elektrolytisches Verfahren zur Gewinnung von Platin hoher Reinheit aus konzentrierten salzsauren Lösungen von Legierungen des Platins mit Rh, Ir und/oder Pd bei gleichzeitiger Abreicherung von anderen Edelmetall- und Unedelmetallverunreinigungen.The present invention relates to an electrolytic process for the production of high purity platinum from concentrated hydrochloric acid solutions of platinum alloys with Rh, Ir and / or Pd with simultaneous depletion of other noble metal and base metal impurities.

Platinlegierungen finden einen vielfältigen Einsatz in der Industrie als Geräteplatin, für Thermoelemente, als Katalysatoren für die Ammoniakoxidation und in der organischen Chemie, für Autoabgaskatalysatoren, in der Dentaltechnik und vielen anderen Bereichen. In Abhängigkeit von den chemischen und anderen Produktionsprozessen werden diese Legierungen nach einer bestimmten Zeit als Platinlegierungsschrotte in die edelmetallverarbeitenden Betriebe gegeben, dort chemisch getrennt und raffiniert.Platinum alloys are widely used in industry as device platinum, for thermocouples, as catalysts for ammonia oxidation and in organic chemistry, for exhaust gas catalysts, in dental technology and many other areas. Depending on the chemical and other production processes, these alloys are given to the precious metal processing plants as platinum alloy scrap after a certain time, where they are chemically separated and refined.

Die klassische Abtrennung des Platins von Rh, Ir und/oder Pd erfolgt über die Fällung als (NH4)2[PtCl6]. Dieses Verfahren ist aber sehr arbeits- und zeitintensiv, bedingt durch die chemisch sehr ähnlichen Eigenschaften der Platinmetalle.The classical separation of the platinum from Rh, Ir and / or Pd takes place by precipitation as (NH 4 ) 2 [PtCl 6 ]. However, this process is very labor intensive and time-consuming due to the chemically very similar properties of the platinum metals.

Besonders kompliziert gestaltet sich die Abtrennung des Platins vom Iridium, da beide in der gleichen stabilen Wertigkeitsstufe (IV) vorliegen und bei Fällung mit NH4Cl Salze mit annähernd gleichen Eigenschaften bilden.The separation of the platinum from the iridium is particularly complicated since both are in the same stable valence level (IV) and, when precipitated with NH 4 Cl, form salts with approximately the same properties.

Eine Grobtrennung ist nur möglich, wenn das IV-wertige Iridium in die III-wertige Oxidationsstufe überführt wird.A rough separation is only possible if the IV-valent iridium is converted into the III-valent oxidation state.

Bei der anschließenden Fällung des Platins mit NH4Cl tritt trotzdem eine Mitfällung des Iridiums auf. Ähnliche Verhältnisse beobachtet man bei der Trennung des Platins vom Rhodium und Palladium. Das ausgefällte (NH4)2[PtCl6] enthält große Anteile an Rhodium und Palladium. Zur weiteren Reinigung sind daher Umfällungs- oder Umkristallisationsstufen erforderlich.When the platinum is subsequently precipitated with NH 4 Cl, the iridium also co-precipitates. Similar relationships are observed in the separation of platinum from rhodium and palladium. The precipitated (NH 4 ) 2 [PtCl 6 ] contains large amounts of rhodium and palladium. Reprecipitation or recrystallization stages are therefore required for further purification.

Aus der DE-PS 2726558 ist ein Verfahren zur Abtrennung des Platins vom Iridium mittels Ionenaustauschern bekannt. Dieses Verfahren führt lediglich zu einem iridiumhaltigen Platin.From DE-PS 2726558 a method for separating the platinum from the iridium by means of ion exchangers is known. This process only leads to platinum containing iridium.

Desweiteren sind zur Trennung von Platinlegierungen eine Vielzahl von Extraktionsverfahren bekannt, die aber ebenfalls eine anschließende Fällung der Platinmetalle erfordern.Furthermore, a large number of extraction processes are known for the separation of platinum alloys, but these also require subsequent precipitation of the platinum metals.

Alle Verfahren erfordern einen hohen apparativen und technischen Aufwand und sind daher sehr kostenintensiv.All processes require a high level of equipment and technology and are therefore very cost-intensive.

Elektrolytische Verfahren zum Raffinieren von Gold sind seit langem bekannt (Gmelin Au, Syst. Nr. 62, 1949) und ständig weiterentwickelt worden (EP 0253783).Electrolytic processes for refining gold have long been known (Gmelin Au, Syst. No. 62, 1949) and have been continuously developed (EP 0253783).

Aus der GB-PS 157785 und der deutschen Patentschrift 594408 sind elektrolytische Platinraffinationsverfahren bekannt, die teilweise mit Kombinationen von chemischen und elektrolytischen Verfahren arbeiten (US-PS 3 891,741).From GB-PS 157785 and German patent 594408 electrolytic platinum refining processes are known, some of which work with combinations of chemical and electrolytic processes (US Pat. No. 3,891,741).

Diese Verfahren sind alle äußerst zeitaufwendig und lassen sich nicht in allen Punkten technisch einwandfrei nachvollziehen.These procedures are all extremely time-consuming and cannot be technically followed in every respect.

Die US-PS 4,382,845 beschreibt eine teilweise elektrolytische Abtrennung von Palladium aus Lösungen, die im Überschuß Palladium enthalten. Eine Trennung ist aber nur bis zu der Grenze möglich, bei der Platin und Palladium im gleichen Verhältnis vorliegen. Die Abtrennung von weiteren Unedel- und Edelmetallen wird in diesem Verfahren nicht erwähnt.US Pat. No. 4,382,845 describes a partial electrolytic separation of palladium from solutions which contain palladium in excess. However, separation is only possible up to the limit at which platinum and palladium are present in the same ratio. The separation of other base and precious metals is not mentioned in this process.

In dem bekannten Verfahren zur Trennung von Platin und Palladium ist die Elektrolysezelle mit einer Kationenaustauschermembran ausgestattet, deren Vorteile allerdings nicht ersichtlich sind, da sich Platin und Palladium in dem angegebenen Konzentrationsverhältnis und dem beschriebenen Spannungsbereich auch ohne Kationenaustauschermembran trennen lassen. Darüber hinaus weist dieses Verfahren den gleichen Nachteil wie auch alle anderen Verfahren auf, daß nur mit einer Maximalkonzentration von ≦ 100g/l gearbeitet werden kann.In the known method for separating platinum and palladium, the electrolysis cell is equipped with a cation exchange membrane, the advantages of which are not apparent, however, since platinum and palladium can also be separated without the cation exchange membrane in the concentration ratio and the voltage range described. In addition, this method has the same disadvantage as all other methods that only a maximum concentration of ≦ 100g / l can be used.

Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren zur Gewinnung von Platin hoher Reinheit zur Verfügung zu stellen, bei dem mit geringen apparativen Mitteln, innerhalb kurzer Zeit, mit minimalen Verlusten, geringem Arbeitsaufwand und ohne Zusatz von teuren Chemikalien Platin von seinen Legierungselementen und Verunreinigungen in einer Reinheit von 99,95 % sich abtrennen läßt.The invention is therefore based on the object of providing a process for the production of platinum of high purity, in which platinum from its alloying elements and impurities is obtained with small apparatus, within a short time, with minimal losses, with little labor and without the addition of expensive chemicals can be separated in a purity of 99.95%.

Überraschenderweise wurde gefunden, daß man auf elektrolytischem Wege aus mit Legierungen des Platins verunreinigten Platinmetallösungen Platin hoher Reinheit bei gleichzeitiger Abreicherung von anderen Edelmetall- und Unedelmetallverunreinigungen gewinnen kann.Surprisingly, it was found that platinum metal solutions contaminated with alloys of platinum can be obtained electrolytically from platinum of high purity with simultaneous depletion of other noble metal and base metal impurities.

Gegenstand der Erfindung ist daher ein elektrolytisches Verfahren zur Gewinnung von Platin hoher Reinheit aus konzentrierten salzsauren Lösungen von Legierungen des Platins mit Rh, Ir und/oder Pd bei gleichzeitiger Abreicherung von anderen Edelmetall- und Unedelmetallverunreinigungen. Das erfindungsgemäße Verfahren zeichnet sich dadurch aus, daß der Reinigungsprozeß in einer Elektrolysezelle, die durch eine Kationenaustauschermembran unterteilt ist, unter potentiostatischen oder spannungskontrollierten Bedingungen von 8 V bis 16 V und einer Stromdichte von 12,5 bis 37,5 A/dm2 erfolgt und die abgeschiedenen Platinlegierungsmetalle aufgearbeitet werden.The invention therefore relates to an electrolytic process for the production of high purity platinum from concentrated hydrochloric acid solutions of platinum alloys with Rh, Ir and / or Pd with simultaneous depletion of other noble metal and base metal impurities. The process according to the invention is characterized in that the cleaning process takes place in an electrolysis cell, which is divided by a cation exchange membrane, under potentiostatic or voltage-controlled conditions of 8 V to 16 V and a current density of 12.5 to 37.5 A / dm 2 and the deposited platinum alloy metals are worked up.

Erfindungsgemäß weisen die salzsauren Lösungen von Legierungen des Platins einen Gehalt von 50 bis 700 g/l und Gesamtverunreinigungen von ≦ 5000 ppm auf.According to the invention, the hydrochloric acid solutions of platinum alloys have a content of 50 to 700 g / l and total impurities of ≦ 5000 ppm.

Bevorzugt werden bei dem erfindungsgemäßen Verfahren Lösungen von Legierungen des Platins mit einem Gehalt von 500 bis 700 g/l eingesetzt.Solutions of platinum alloys with a content of 500 to 700 g / l are preferably used in the process according to the invention.

Die für das erfindungsgemäße Verfahren eingesetzten konzentrierten Lösungen der Legierungen des Platins weisen Verunreinigungen der Elemente Au und/oder Ag, Cu, Fe, Co, Ni, Sb, As, Pb, Cd, Al, Mn, Mo, Si, Zn, Sn, Zr, W, Ti, Cr auf.The concentrated solutions of the platinum alloys used for the process according to the invention contain impurities in the elements Au and / or Ag, Cu, Fe, Co, Ni, Sb, As, Pb, Cd, Al, Mn, Mo, Si, Zn, Sn, Zr, W, Ti, Cr on.

Als Anodenflüssigkeit werden salzsaure Platinmetallösungen, bevorzugt Hexachlorplatinsäure, und als Katodenflüssigkeit 6 bis 8 N Salzsäure, bevorzugt 6 N Salzsäure, eingesetzt.Hydrochloric acid platinum metal solutions, preferably hexachloroplatinic acid, are used as the anode liquid, and 6 to 8 N hydrochloric acid, preferably 6 N hydrochloric acid, are used as the cathode liquid.

Die Anode besteht aus Platinmetall, während die Katode aus Platinmetall, Titan oder Graphit beschaffen ist.The anode is made of platinum metal, while the cathode is made of platinum metal, titanium or graphite.

Als bevorzugte mit Sulfonsäuregruppen beladene Kationenaustauschermembran wird eine Teflonmembran (Nafion® - Membran) eingesetzt. Das erfindungsgemäße Verfahren arbeitet bevorzugt unter potentiostatischen oder spannungskontrollierten Bedingungen von 11,5 V bis 12 V und einer Stromdichte von 22,5 bis 35 A/dm2.A Teflon membrane (Nafion® membrane) is used as the preferred cation exchange membrane loaded with sulfonic acid groups. The method according to the invention preferably works under potentiostatic or voltage-controlled conditions of 11.5 V to 12 V and a current density of 22.5 to 35 A / dm 2 .

An der Katode scheiden sich die Unedelmetall- und Edelmetallverunreinigungen mit geringen Anteilen von Platinmetallen ab. Überraschenderweise wurde gefunden, daß sich an der Anode die Legierungsbestandteile Ir, Rh und/oder Pd gemeinsam mit geringen Anteilen des Platins abscheiden.The base metal and noble metal impurities are deposited on the cathode with a small proportion of platinum metals. Surprisingly, it was found that the alloy constituents Ir, Rh and / or Pd deposit together with small amounts of the platinum on the anode.

Aufgrund der höheren Konzentration der Platinlegierungslösung und des erfindungsgemäß angewendeten höheren Spannungsbereichs des erfindungsgemäßen Verfahrens wurde die überraschende Abscheidung der Legierungsbestandteile an der Anode erreicht.Due to the higher concentration of the platinum alloy solution and the higher voltage range of the method according to the invention used, the surprising deposition of the alloy components at the anode was achieved.

Der Niederschlag an der Katode wird von dieser mechanisch entfernt und gesondert aufgearbeitet.The precipitate on the cathode is mechanically removed from it and processed separately.

Das auf der Anode abgeschiedene Ir, Rh und/oder Pd wird nach der Überführung in die Lösung durch eine erneute Elektrolyse raffiniert.The Ir, Rh and / or Pd deposited on the anode is refined after being transferred to the solution by renewed electrolysis.

Das sich bei dem erfindungsgemäßen Verfahren entwickelnde Chlorgas wird nach bekannten Methoden abgeführt.The chlorine gas developing in the process according to the invention is removed by known methods.

Aus den durch das erfindungsgemäße Verfahren gereinigten Lösungen der Platinmetallegierungen kann nach bekannten Methoden das metallische Platin elektrolytisch oder chemisch zurückgewonnen werden.From the solutions of the platinum metal alloys cleaned by the process according to the invention, the metallic platinum can be recovered electrolytically or chemically by known methods.

Mit dem erfindungsgemäßen Verfahren sind folgende Vorteile verbunden:

  • es erfordert einen minimalen apparativen und sicherheitstechnischen Aufwand
  • es arbeitet mit minimaler ökologischer Belastung
  • es ist gegenüber den herkömmlichen Verfahren wesentlich zeit- und kostensparender.
The following advantages are associated with the method according to the invention:
  • it requires a minimal outlay in terms of equipment and safety
  • it works with minimal ecological impact
  • it is much more time and cost saving compared to conventional processes.

Die Erfindung wird nachstehend an einigen Beispielen näher erläutert.The invention is explained in more detail below using a few examples.

Beispiel 1example 1 Elektrolytische Trennung von Platin-Iridium-1Electrolytic separation of platinum-iridium-1

Eine salzsaure Platin-Iridium-1-Lösung mit einem Gehalt von 300 g/l und folgenden Verunreinigungen (bezogen auf den Platinmetallgehalt)

Au
20 ppm
Fe
136 ppm
Ni
534 ppm
Cu
960 ppm
Pb
24 ppm
Cd
12 ppm
Zn
16 ppm
wird in einer Elektrolysezelle, in der Katode und Anode durch eine Kationenaustauschermembran unterteilt sind, bei einer Spannung von 12 V und einer Stromdichte von 27,5 A/dm2 elektrolysiert. Nach einer Elektrolysezeit von 20 Stunden sind die Unedelmetalle und das Gold auf eine Endkonzentration von ≦ 20 ppm abgereichert, das Rhodium auf eine Konzentration von 150 ppm und das Iridium auf 0,5 %. Die Palladiumtrennung erfolgt im stark sauren Medium in geringeren Anteilen. Nach einer weiteren Elektrolysezeit von 20 Stunden liegt der Iridiumgehalt ≦ 200 ppm, der Rhodiumgehalt ≦ 20 ppm und der Palladiumgehalt ≦ 100 ppm.A hydrochloric acid platinum-iridium-1 solution with a content of 300 g / l and the following impurities (based on the platinum metal content)
Au
20 ppm
Fe
136 ppm
Ni
534 ppm
Cu
960 ppm
Pb
24 ppm
CD
12 ppm
Zn
16 ppm
is electrolyzed in an electrolysis cell in which the cathode and anode are divided by a cation exchange membrane at a voltage of 12 V and a current density of 27.5 A / dm 2 . After an electrolysis time of The base metals and gold are depleted to a final concentration of ≦ 20 ppm for 20 hours, the rhodium to a concentration of 150 ppm and the iridium to 0.5%. Palladium is separated in small amounts in a strongly acidic medium. After a further electrolysis time of 20 hours, the iridium content is ≦ 200 ppm, the rhodium content ≦ 20 ppm and the palladium content ≦ 100 ppm.

Beispiel 2Example 2 Elektrolytische Trennung von Platin-Rhodium-5Electrolytic separation of platinum-rhodium-5

Eine salzsaure Lösung von Platin-Rhodium-5 mit einem Platinmetallgehalt von 250 g/l und folgenden Verunreinigungen (bezogen auf den Platinmetallgehalt)

Ir
250 ppm
Pd
500 ppm
Au
150 ppm
Fe
210 ppm
Ni
453 ppm
Cu
760 ppm
Pb
55 ppm
Cd
22 ppm
Zn
40 ppm
wird in einer Elektrolysezelle, in der Katode und Anode durch eine Kationenaustauschermembran unterteilt sind, bei einer Spannung von 15 V und einer Stromdichte von 32,5 bis 35 A/dm2 elektrolysiert. Die Unedelmetallverunreinigungen und das Gold werden innerhalb von 20 Stunden auf eine Konzentration von ≦ 20 ppm abgereichert, das Palladium auf eine Konzentration von 400 ppm und das Rhodium auf eine Konzentration von 1,2 %. Nach einer anschließenden Elektrolysezeit von 25 Stunden stellt man eine Abreicherung des Rhodiums auf eine Konzentration von ≦ 200 ppm und des Palladiums auf ≦ 100 ppm fest.A hydrochloric acid solution of platinum-rhodium-5 with a platinum metal content of 250 g / l and the following impurities (based on the platinum metal content)
Ir
250 ppm
Pd
500 ppm
Au
150 ppm
Fe
210 ppm
Ni
453 ppm
Cu
760 ppm
Pb
55 ppm
CD
22 ppm
Zn
40 ppm
is electrolyzed in an electrolysis cell in which the cathode and anode are divided by a cation exchange membrane at a voltage of 15 V and a current density of 32.5 to 35 A / dm 2 . The base metal impurities and the gold are depleted within 20 hours to a concentration of ≦ 20 ppm, the palladium to a concentration of 400 ppm and the rhodium to one Concentration of 1.2%. After a subsequent electrolysis time of 25 hours, the rhodium is depleted to a concentration of ≦ 200 ppm and the palladium to ≦ 100 ppm.

Beispiel 3Example 3 Elektrolytische Trennung von Platin-Palladium-5Electrolytic separation of platinum-palladium-5

Eine salzsaure Lösung von Platin-Palladium-5 mit einem Metallgehalt von 100 g/l und folgenden Verunreinigungen (bezogen auf den Platinmetallgehalt)

Ir
400 ppm
Rh
450 ppm
Au
80 ppm
Fe
160 ppm
Ni
500 ppm
Cu
810 ppm
Pb
76 ppm
Cd
15 ppm
Zn
43 ppm
wurde in einer Elektrolyzelle, in der Katode und Andode durch eine Kationenaustauschermembran unterteilt sind, bei einer Spannung von 11,5 V und einer Stromdichte von 22,5 A/dm2 elektrolysiert. Die Abreicherung der Unedelmetalle und des Goldes erfolgt innerhalb von 10 Stunden auf Gehalte von ≦ 20 ppm, die des Iridiums und Rhodiums auf Konzentrationen von ≦ 100 ppm und des Palldiums auf 2,3 %. Nach einer weiteren Elektrolysezeit von 15 Stunden erreicht man eine Abreicherung des Palladiums auf Werte von ≦ 500 ppm.A hydrochloric acid solution of platinum-palladium-5 with a metal content of 100 g / l and the following impurities (based on the platinum metal content)
Ir
400 ppm
Rh
450 ppm
Au
80 ppm
Fe
160 ppm
Ni
500 ppm
Cu
810 ppm
Pb
76 ppm
CD
15 ppm
Zn
43 ppm
was electrolyzed in an electrolytic cell in which the cathode and andode are divided by a cation exchange membrane at a voltage of 11.5 V and a current density of 22.5 A / dm 2 . The depletion of the base metals and gold takes place within 10 hours to a content of ≦ 20 ppm, that of the iridium and rhodium to concentrations of ≦ 100 ppm and the palladium to 2.3%. After a further electrolysis time of 15 hours, the palladium is depleted to values of ≦ 500 ppm.

Claims (15)

  1. Electrolytic process for obtaining high-purity platinum from concentrated hydrochloric acid solutions of alloys of platinum with Rh, Ir and/or Pd, with a simultaneous reduction in other noble and base metal impurities, characterised in that the purification process takes place in an electrolytic cell which is subdivided by a cation exchange membrane, under potentiostatic or voltage-controlled conditions of from 8 V to 16 V and at a current density of from 12.5 to 37.5 A/dm2, and the platinum alloy metals which are deposited are worked up.
  2. Process according to Claim 1, characterised in that the concentrated hydrochloric acid solutions of platinum alloys contain from 50 to 700 g/l platinum and ≦ 5000 total impurities.
  3. Process according to Claim 2, characterised in that the concentrated hydrochloric acid solutions contain from 500 to 700 g/l platinum alloys.
  4. Process according to at least one of Claims 1 to 3, characterised in that the concentrated solutions of platinum alloys contain impurities of the elements Au and/or Ag, Cu, Fe, Co, Ni, Sb, As, Pb, Cd, Al, Mn, Mo, Si, Zn, Sn, Zr, W, Ti and Cr.
  5. Process according to at least one of Claims 1 to 4, characterised in that a hydrochloric acid solution of platinum metal alloys is utilised as the anode fluid and 6N to 8N hydrochloric acid is utilised as the cathode fluid.
  6. Process according to Claim 5, characterised in that hexachloroplatinic acid is utilised as the anode fluid.
  7. Process according to Claim 5, characterised in that 6N hydrochloric acid is utilised as the cathode fluid.
  8. Process according to at least one of Claims 1 to 7, characterised in that the purification process takes place under potentiostatic or voltage-controlled conditions of from 11.5 to 12 V and at a current density of from 22.5 to 35 A/dm2.
  9. Process according to at least one of Claims 1 to 8, characterised in that the chlorine gas generated during the electrolysis is removed by known methods.
  10. Process according to at least one of Claims 1 to 9, characterised in that platinum metal is utilised as the anode and platinum metal, titanium or graphite are utilised as the cathode.
  11. Process according to at least one of Claims 1 to 10, characterised in that a Teflon membrane is utilised as the cation exchange membrane.
  12. Process according to at least one of Claims 1 to 11, characterised in that the alloy constituents Ir, Rh and/or Pd are deposited at the anode and the base and noble metal impurities are deposited at the cathode, in each case with small amounts of platinum.
  13. Process according to Claim 12, characterised in that the deposit is removed mechanically from the cathode and is worked up separately.
  14. Process according to Claim 12, characterised in that the deposit is removed mechanically from the anode, is converted into solution and is refined by a further electrolysis.
  15. Process according to at least one of Claims 1 to 11, characterised in that the metallic platinum is recovered electrolytically or chemically by known methods from the purified solutions of the platinum metal alloys.
EP93118979A 1992-12-18 1993-11-25 Electrolytic process for obtaining high purity platinum from platinum alloys Expired - Lifetime EP0602426B1 (en)

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Application Number Priority Date Filing Date Title
DE4243697 1992-12-18
DE4243697A DE4243697C1 (en) 1992-12-18 1992-12-18 Electrolytic recovery of high purity platinum@ - using concentrated hydrochloric acid solns. contg. alloys in cell contg. cation exchange membrane

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EP (1) EP0602426B1 (en)
JP (1) JP3227656B2 (en)
AT (1) ATE138980T1 (en)
CA (1) CA2111792C (en)
DE (2) DE4243697C1 (en)
FI (1) FI100605B (en)
RU (1) RU2093606C1 (en)
ZA (1) ZA938995B (en)

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DE19928027C2 (en) * 1999-06-18 2002-06-27 Heraeus Gmbh W C Process for the production of platinum
KR100512644B1 (en) * 2000-05-22 2005-09-07 가부시키 가이샤 닛코 마테리알즈 Method of producing a higher-purity metal
US7255798B2 (en) * 2004-03-26 2007-08-14 Ion Power, Inc. Recycling of used perfluorosulfonic acid membranes
GB0408805D0 (en) * 2004-04-08 2004-05-26 Accentus Plc Precious metal recovery
DE102006056017B4 (en) * 2006-11-23 2016-02-18 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Process for the recovery of precious metals
KR101349305B1 (en) * 2013-05-24 2014-01-13 한국지질자원연구원 Device for electrowinning rare metals using channelled cell, and method thereof
CN105063660B (en) * 2015-08-03 2017-07-04 中南大学 A kind of method that nano-silicon powder is directly prepared in electrorefining processes
CN111926195B (en) * 2020-06-24 2022-03-08 重庆材料研究院有限公司 Method for preparing high-purity platinum powder from platinum alloy waste
US11319613B2 (en) 2020-08-18 2022-05-03 Enviro Metals, LLC Metal refinement

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GB157785A (en) * 1919-12-19 1922-04-10 Eulampiu Slatineanu Electrolytic process and apparatus for the separation of platinum from other metals contained in platiniferous materials
DE594408C (en) * 1928-10-13 1934-03-16 Degussa Process for refining platinum
US3891741A (en) * 1972-11-24 1975-06-24 Ppg Industries Inc Recovery of fission products from acidic waste solutions thereof
ZA763681B (en) * 1976-06-21 1978-02-22 Nat Inst Metallurg The recovery and purification of iridium
US4382845A (en) * 1981-08-10 1983-05-10 Chevron Research Company Selective electrowinning of palladium
US4775452A (en) * 1985-04-25 1988-10-04 Chlorine Engineers Corp. Ltd. Process for dissolution and recovery of noble metals
AU607921B2 (en) * 1986-07-16 1991-03-21 Tanaka Kikinzoku Kogyo K.K. Process for refining gold and apparatus employed therefor
JPH0238536A (en) * 1988-07-29 1990-02-07 Tanaka Kikinzoku Kogyo Kk Separation of noble metal in acidic iridium solution

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ZA938995B (en) 1994-08-03
DE59302820D1 (en) 1996-07-11
JP3227656B2 (en) 2001-11-12
FI935659A0 (en) 1993-12-16
US5393388A (en) 1995-02-28
CA2111792A1 (en) 1994-06-19
DE4243697C1 (en) 1994-03-17
JPH06280075A (en) 1994-10-04
ATE138980T1 (en) 1996-06-15
EP0602426A1 (en) 1994-06-22
FI100605B (en) 1998-01-15
FI935659A (en) 1994-06-19
CA2111792C (en) 2003-11-11
RU2093606C1 (en) 1997-10-20

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