CN112119171A

CN112119171A - Method and device for obtaining gold and/or silver and/or at least one platinum group metal

Info

Publication number: CN112119171A
Application number: CN201980034298.9A
Authority: CN
Inventors: H·鲍尔; C·鲍迪尚; J·哈肯伯格
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-05-23
Filing date: 2019-05-07
Publication date: 2020-12-22
Also published as: DE102018208079A1; EP3797178A1; WO2019223996A1

Abstract

The invention relates to a device for obtaining gold and/or silver and/or at least one platinum group metal from a starting material (11). The device has a container (20) arranged for receiving the starting material (11) and for receiving an electrolyte solution. At least one gas outlet unit (30) is arranged at the upper side (21) of the container (20). At least one circulation line (40) has an inlet unit (41) and an outlet unit (42), wherein the inlet unit (41) and the outlet unit (42) are each arranged on the container (20). At least one gas introduction unit (50) is arranged in the circulation line (40). At least one source of oxidizing agent (51) and at least one source of reducing agent (52) are each connected to at least one gas introduction unit (50). In a method for obtaining gold and/or silver and/or at least one platinum group metal from the starting material (11), the starting material (11) is placed in the container (20) and covered with the electrolyte solution (12). Circulating the electrolyte solution (12) through the circulation line (40). Alternately introducing at least one gaseous oxidizing agent and at least one gaseous reducing agent into the electrolyte solution (12) by means of the at least one gas introduction unit (50).

Description

Method and device for obtaining gold and/or silver and/or at least one platinum group metal

Technical Field

The invention relates to a device for obtaining gold and/or silver and/or at least one platinum group metal from a starting material. Furthermore, the invention relates to a method for obtaining gold and/or silver and/or at least one platinum group metal using the device.

Background

Gold, silver and platinum group metals, such as platinum, palladium, ruthenium, rhenium and iridium are indispensable raw materials. Its recovery from scrap metal (e.g., as part of a catalyst material or electronic device) can be achieved by pyrometallurgical or hydrometallurgical means. Pyrometallurgical recovery is achieved by melting scrap metal and then post-treating by various methods. However, this is very energy consuming and is associated with the production of toxic emissions.

In the recovery by hydrometallurgical means, the metal to be recovered is introduced into the aqueous solution by forming a complex. An example of this method is described in the article "Platinum recycling green via induced surface potential alteration engineering fast and effective resolution" by N.Hodnik, C.Baldizzone, 2016, Nature communications, Vol.7. Here, platinum and palladium can be recovered from the industrial catalyst at pH 1 using chloride as a complexing agent. The recovery of ruthenium and iridium using chloride as a complexing agent can be carried out at a pH in the range of 13 to 14. Here, the oxidizing agent and the reducing agent are used alternately.

Disclosure of the invention

An apparatus for obtaining gold and/or silver and/or at least one platinum group metal from a starting material has a container configured to receive the starting material and to receive an electrolyte solution. The platinum group metals (platinum group metals; PGM) are understood here to mean the light platinum group metals ruthenium, rhodium and palladium and the heavy platinum group metals osmium, iridium and platinum. The electrolyte solution is in particular an aqueous solution containing chloride, bromide and/or iodide anions as complexing agents for gold and/or silver and/or at least one platinum group metal. These may be contained in the electrolyte solution, for example, as alkali metal chlorides, alkali metal bromides, and/or alkali metal iodides. The pH of the electrolyte solution may be selected according to the complexing agent. When alkali chlorides are used, a pH of less than 3 is preferred. When alkali metal iodides are used, in particular a pH of up to 10 may be set.

At least one gas lead-out unit is arranged at an upper side of the container. Furthermore, the device has at least one circulation line with an inlet unit and an outlet unit. The introduction unit and the discharge unit are respectively arranged on the containers. The introduction unit and the discharge unit are provided for introducing the electrolyte solution from the circulation line into the container by the introduction unit and discharging it from the container again by the discharge unit. The recycle line enables continuous or discontinuous replacement of the electrolyte solution in the container. For this purpose, the insertion unit or the removal unit is preferably arranged on or next to the upper side of the container and the other of the elements is arranged on or next to the lower side of the container, wherein the upper side and the lower side are opposite. At least one gas introduction unit is disposed in the circulation line. An oxidant source is connected to at least one such gas introduction unit. In particular, the oxidant source provides ozone as the gaseous oxidant. The reducing agent source is connected to at least one gas introduction unit, which may be the same or different gas introduction unit as the introduction unit providing the oxidant gas. The reducing agent source supplies in particular hydrogen as gaseous reducing agent to the gas introduction unit. It is also preferred that the apparatus further has an inert gas source and/or a carbon monoxide source, which are connected to the at least one gas introduction unit, respectively. Particularly preferably, it is connected to the same gas introduction unit to which the reducing agent source is also connected. The inert gas source provides, inter alia, nitrogen or a noble gas.

The device is suitable for being able to obtain gold and/or silver and/or at least one platinum group metal from a starting material, wherein the metal is temporarily dissolved by alternating oxidation and reduction. Here, the metal cations are complexed by the anions of the electrolyte solution in the solution and are thus stabilized. The inert gas source may be used to flush the oxidant from the electrolyte solution and then introduce the reductant thereto, and may be used to flush the reductant from the reductant source and then introduce the oxidant thereto. The use of carbon monoxide is advantageous because carbon monoxide is a strong reducing agent for platinum complexes. In addition, carbon monoxide adsorbs on the platinum surface, and therefore platinum precipitation is prevented when a reducing agent is introduced into the electrolyte solution.

In a method for obtaining gold and/or silver and/or at least one platinum group metal from a starting material, the starting material is placed in a container and covered with an electrolyte solution. The electrolyte solution is circulated continuously or discontinuously through the circulation line. By means of the at least one gas introduction unit, at least one gaseous oxidizing agent and at least one gaseous reducing agent are alternately introduced into the electrolyte solution, so that the starting material can be treated therewith.

Preferably, a metal extractor is arranged in the circulation line, which metal extractor is provided for binding gold and/or silver and/or salts of at least one platinum group metal. By allowing the metal ions dissolved in the electrolyte solution to be continuously bound by ion exchange, the electrolyte solution is not saturated with metal ion complexes, which has a favorable effect on the dissolution kinetics. Particularly preferably, the metal extractor is arranged upstream of the gas introduction unit in the circulation line. In this way, the metal ion complex is always first removed from the electrolyte solution, and then a gaseous oxidizing agent or a gaseous reducing agent is added thereto to further treat the starting material. This prevents undesirable metal precipitation during the introduction of the gas.

In one embodiment, the metal extractor comprises at least one further source of reducing agent for metal precipitation and at least one adsorbent, such as in particular activated carbon. In another embodiment, the metal extractor is a device for metal electrochemical displacement precipitation (Zementation). In yet another embodiment, the metal extractor is an ion exchange column having an ion exchange resin selective for gold cations, silver cations, and/or platinum group metal cations.

In the following, various embodiments of the device and method are described, which are able to obtain gold and/or silver and/or at least one platinum group metal by means of a temporary obtaining method:

in a first embodiment of the apparatus, the vessel is configured as a distillation column having a plurality of floors or intermediate floors. Distillation columns are used in the chemical industry for large scale distillation separations. The bottom plate of the vessel, which may be constructed in various forms, is arranged to first receive the liquid condensed during the distillation and then to direct it back to the bottom of the distillation column. In the process for obtaining gold and/or silver and/or at least one platinum group metal, when using the apparatus according to the first embodiment, the starting materials are placed on the bottom plate of the distillation column. The starting material is thus fixed and the distillation column is then filled with electrolyte solution via the circulation line. This enables good contact of the starting materials with the electrolyte solution and the oxidizing or reducing agent dissolved therein.

In a second embodiment of the apparatus, the vessel is configured as a heterogeneous reactor. This enables receiving a quantity of starting material which may be suspended in the electrolyte solution in the container. In order to be able to exchange the electrolyte solution in the container continuously or discontinuously during the harvesting process, it is further preferred that the introduction unit of the electrolyte solution is located at or beside the lower side of the container and the discharge unit is located at or beside the upper side thereof. By using this embodiment of the device, the method can be carried out such that the starting material is present in the form of particles of less than 0.1mm, wherein the particles represent at most 10% by volume of the total volume of the electrolyte solution and the particles. Such fine and such finely distributed particles may form a suspension with the electrolyte solution throughout the vessel, thereby enabling contact between the starting material, the electrolyte solution and the introduced gas throughout the volume of the vessel. In addition, the container can be filled with starting material by flushing the starting material into the container through the circulation line by means of the electrolyte.

In a third embodiment of the apparatus, the vessel is configured as a bed reactor, in particular as a fixed bed reactor (fixed bed reactor; FBR), a fluidized bed reactor or a moving bed reactor (moving bed reactor; MBR) or a rotating bed reactor (rotating bed reactor; RBR). It has an inlet unit for the electrolyte solution at or beside its upper side and an outlet unit for the electrolyte solution at or beside its lower side. Pellets of starting material may be fixed in a bed reactor and simultaneously treated in a stream of electrolyte solution. In order to fix the starting material in the bed reactor, a closed basket receiving the starting material may be arranged in particular in the vessel. The basket may be rotatably disposed in the rotating bed reactor. In using this embodiment of the apparatus, the starting material should be present in the form of particles larger than 0.2 mm. Unlike when using heterogeneous reactors, such large particles no longer form a suspension throughout the electrolyte solution, but fall back again and again to the vessel floor or basket floor. However, the bed reactor allows a larger amount of starting material to be placed in a vessel of a given size than would be the case in a non-homogeneous reactor. The particles may comprise 20 to 40 volume percent of the total volume of the electrolyte solution and the particles.

If, in the description of the different embodiments of the device, reference is made to an arrangement next to the lower side or next to the upper side of the container, this does not refer to an interface through the upper side or the lower side, but to an interface arranged at the side wall of the container facing the lower side or the upper side. Here, the interface arranged next to the lower side is located in the side wall closer to the lower side than the upper side, and the interface arranged next to the upper side is located in the side wall closer to the upper side than the lower side.

Brief Description of Drawings

Embodiments of the invention are illustrated in the drawings and set forth in detail in the following description.

Fig. 1 shows a schematic cross-sectional view of a device according to an embodiment of the invention.

Fig. 2 shows a schematic cross-sectional view of a device according to a second embodiment of the invention.

Fig. 3 shows a schematic cross-sectional view of a device according to a third embodiment of the invention.

Examples of the invention

In a first embodiment of the invention, the device for obtaining gold and/or silver and/or at least one platinum group metal from the starting material 11 has a vessel 20 in the form of a distillation column. The container 20 has an upper side 21 and a lower side 22. The gas lead-out unit 30 is arranged at the upper side 21 of the container 20. The gas outlet unit 30 serves at the same time as an inlet unit 41 of the circulation line 40. A lead-out unit 42 at the other end of the circulation line 40 is arranged beside the bottom side 22 of the container 20 and in a side wall thereof. The electrolyte storage tank 43 is connected to the circulation line 40 by a first three-way valve 44, and a second three-way valve 45 connects the circulation line 40 above the gas lead-out unit 30 to an outlet 46. A gas introduction unit 50 in the form of a venturi nozzle is arranged in the circulation line 40. It is connected to an ozone generator as the oxidizing agent source 51 and to a reducing agent source 52, which is provided for introducing hydrogen and additionally has a nitrogen source and a carbon monoxide source, which are not shown. In this connection, a third three-way valve 53 is arranged, via which only either the oxidizing agent source 51 or the reducing agent source 52 is always connected to the gas introduction unit 50. A metal extractor 60 in the form of an ion exchange column is disposed between the first three-way valve 44 and the gas introduction unit 50. The distillation column has three

floors

71, 72, 73.

In a first embodiment of the method, the starting material 11 is first placed on the

bottom plates

71, 72, 73. These starting materials 11 are obtained from pulverized fuel cells. An electrolyte solution containing 3 mol/l NaCl and 0.001 mol/l HCl and having a pH of 3 is introduced from an electrolyte storage tank 43 through a first three-way valve 44 into the circulation line 40. It passes through a metal extractor 60 arranged to bind metal ions dissolved in the electrolyte solution by ion exchange. Since the electrolyte solution also does not contain metal ions at the start of the process, it does not interact with the metal extractor 60. It is enriched with ozone generated by the ozone generator 51 by means of the gas introduction unit 50 and then introduced into the container 20 through the second three-way valve 45. It fills the container 20 so that ozone can react with the starting material 11, wherein the metal ions enter the solution as complexes. During the reaction, the second three-way valve 45 is opened so that gas escaping from the electrolyte solution can pass through the gas outlet 30 to the outlet 46 in order to leave the device there. The outlet 46 is connected to an ozone decomposer, not shown. After the oxidation step is completed, the electrolyte solution is again introduced into the metal extractor 60 through the circulation line 40, thereby binding the complexed metal ions at this time. Nitrogen is then added to the electrolyte solution circulating at this time in the flushing step by means of the gas introduction unit 50 to drive out residual ozone still in the container 20 therefrom. Then, in the reduction step, a mixture of hydrogen and carbon monoxide is introduced into the electrolyte solution by means of the gas introduction unit 50, and these reducing agents are reacted with the starting material 11. Here, other metal ions bound by the metal extractor 60 enter the solution. The reduction step is followed by an additional flushing step with nitrogen gas to drive off residual reducing agent from vessel 20. The process then starts again with an oxidation step. This is continued until a concentration sensor, not shown, indicates that no further metal has dissolved from the starting material 11. In this case, the first three-way valve 44 is switched so that the electrolyte solution is pumped from the container 20 back into the electrolyte storage tank 43, and the method is thereby ended.

In a second embodiment of the apparatus shown in fig. 2, the vessel 20 is manufactured as a heterogeneous reactor. The lead-in unit 41 of the circulation line 40 is arranged in the lower side of the vessel 20 and the lead-out unit 42 is arranged in its side wall beside its upper side 41. The gas outlet 30 is arranged at the upper side 21 of the vessel 20 and is not connected to the circulation line 40. The circulation line 40 has neither three-

way valves

44, 45 nor the electrolyte storage tank 43. The gas introduction unit 50 manufactured as in the first embodiment is arranged downstream of the metal extractor 60 in the circulation line 40. The branch of the circulation line 40, not shown, near the inlet 41 enables particles of less than 0.1mm of the starting material 11 to be flushed into the container 20 together with the electrolyte solution 12 until the container is filled with the electrolyte solution 12. Here, the particles of the starting material 11 account for 5 vol% of the total volume of the starting material 11 and the electrolyte solution 12 in the container 20. By using this apparatus, the gas treatment in the method for obtaining gold and/or silver and/or at least one platinum group metal is performed in the same manner as in the first embodiment, and the metal ions are combined by means of the metal extractor 60 in the same manner.

In a third embodiment of the apparatus, the vessel 20 is manufactured as a rotating bed reactor. As shown in fig. 3, this embodiment of the device differs from the second embodiment in that, on the one hand, the introduction unit 41 and the discharge unit 42 are exchanged for each other and, on the other hand, a closure basket 80 is arranged in the container 20. Which receives the starting materials 11 and fixes them. The starting material 11 arranged in the basket 80 is present in the form of granular particles larger than 0.2 mm. The mesh of the basket 80 is less than 0.2mm so that the pellets cannot exit the basket 80 either upwardly or downwardly. In the present embodiment, the total volume of the starting material 11 and the electrolyte solution 12 in the container 20 is 30 vol%. By using the apparatus, the gas treatment in the method for obtaining gold and/or silver and/or at least one platinum group metal is performed in the same manner as in the first embodiment, and the metal ions are combined by means of the metal extractor 60 in the same manner. Here, the basket 80 is rotated about its longitudinal axis in the flow of electrolyte solution 12.

Claims

1. A device for extracting gold and/or silver and/or at least one platinum group metal from a starting material (11) has

-a container (20) arranged for receiving the starting material (11) and for receiving an electrolyte solution (12),

-at least one gas lead-out unit (30) arranged at an upper side (21) of the container (20),

-at least one circulation line (40) with an introduction unit (41) and a discharge unit (42), wherein the introduction unit (41) and the discharge unit (42) are each arranged on the container (20),

-at least one gas introduction unit (50) arranged in the circulation line (40),

-at least one source of oxidizing agent (51) and at least one source of reducing agent (52), each connected to at least one gas introduction unit (50).

2. The device according to claim 1, characterized in that, in addition, an inert gas source and/or a carbon monoxide source are connected to at least one gas introduction unit (50), respectively.

3. The apparatus according to claim 1 or 2, characterized in that a metal extractor (60) is arranged in the circulation line (40), which metal extractor is provided for binding gold and/or silver and/or salts of at least one platinum group metal.

4. The apparatus according to claim 3, characterized in that the metal extractor (60) is arranged upstream of the gas introduction unit (50) in the circulation line (40).

5. The device according to any one of claims 1 to 4, characterized in that the container (20) is configured as a distillation column having a plurality of floors (71, 72, 73).

6. The device according to any one of claims 1 to 4, characterized in that the vessel (20) is configured as a heterogeneous reactor.

7. Device according to claim 5 or 6, characterized in that the lead-in unit (41) is arranged at or beside the lower side (22) of the container (20) and the lead-out unit (42) is arranged at or beside the upper side (21) of the container (20).

8. The apparatus according to any one of claims 1 to 4, characterized in that the vessel (20) is configured as a bed reactor having an introduction unit (41) at or beside its upper side (21) and a discharge unit (42) at or beside its lower side (22).

9. Method for obtaining gold and/or silver and/or at least one platinum group metal from a starting material (11), wherein the starting material (11) is placed in a container (20) of an apparatus according to any one of claims 1 to 8 and covered with an electrolyte solution (12), the electrolyte solution (12) is circulated through the circulation line (40), and at least one gaseous oxidizing agent and at least one gaseous reducing agent are alternately introduced into the electrolyte solution (12) through the at least one gas introduction unit (50).

10. Method according to claim 9, characterized in that the device is a device according to claim 5 and the starting material (11) is placed on a bottom plate (71, 72, 73) and the container (20) is then filled with the electrolyte solution (12).

11. The method according to claim 9, characterized in that the device is according to claim 6 and the starting material (11) is present in the form of particles smaller than 0.1mm, wherein the particles represent at most 10 vol-% of the total volume of the electrolyte solution (12) and the particles.

12. The method according to claim 9, wherein the device is according to claim 8 and the starting material (11) is present in the form of particles larger than 0.2mm, wherein the particles represent 20 to 40 vol-% of the total volume of the electrolyte solution (12) and the particles.