Method And System For Extracting Metal And Oxygen From Powdered Metal Oxides

Abstract

A method for extracting metal and oxygen from powdered metal oxides in electrolytic cell is proposed, the electrolytic cell comprising a container, a cathode, an anode and an oxygen-ion-conducting membrane, the method comprising providing a solid oxygen ion conducting electrolyte powder into a container, providing a feedstock comprising at least one metal oxide in powdered form into the container, applying an electric potential across the cathode and the anode, the cathode being in communication with the electrolyte powder and the anode being in communication with the membrane in communication with the electrolyte powder, such that at least one respective metallic species of the at least one metal oxide is reduced at the cathode and oxygen is oxidized at the anode to form molecular oxygen, wherein the potential across the cathode and the anode is greater than the dissociation potential of the at least one metal oxide and less than the dissociation potential of the solid electrolyte powder and the membrane.

Claims

1. A method for extracting metal and oxygen from powdered metal oxides in an electrolytic cell, comprising a container, a cathode, an anode and an oxygen-ion-conducting membrane, the method comprising: providing a solid oxygen ion conducting electrolyte powder into a container, providing a feedstock comprising at least one metal oxide in powdered form into the container, applying an electric potential across the cathode and the anode, the cathode being in communication with the electrolyte powder and the anode being in communication with the membrane in communication with the electrolyte powder, such that at least one respective metallic species of the at least one metal oxide is reduced at the cathode and oxygen is oxidized at the anode to form molecular oxygen, wherein the potential across the cathode and the anode is greater than the dissociation potential of the at least one metal oxide and less than the dissociation potential of the solid electrolyte powder and the membrane.

2. The method of claim 1, further comprising mixing the electrolyte powder and the feedstock.

3. The method of claim 1, wherein the feedstock comprises at least one of a group of materials or a chemical compound comprising at least one of the group of materials, the group consisting of: iron, titanium, regolith.

4. The method of claim 1, wherein the electrolyte powder comprises at least one of a group of materials, the group consisting of rare earth or alkaline earth-doped zirconia-, ceria-, hafnia-, and thoria-based oxides.

5. The method of claim 1, wherein the electrolyte powder comprises mixed oxygen ion electronic conductors.

6. The method of claim 1, wherein the oxygen ion-conducting membrane is selected from a group of materials, the group comprising rare earth or alkaline earth-doped zirconia-, ceria-, hafnia-, and thoria-based oxides.

7. The method of claim 6, wherein the membrane comprises yttria-stabilized zirconia.

8. The method of claim 1, wherein a mean particle size of the solid electrolyte powder is less than a mean particle size of the feedstock powder.

9. The method of claim 1, wherein the electrolytic cell is operated at a temperature greater than about 500° C.

10. The method of claim 1, wherein the electrolytic cell is operated at a temperature in the range of about 500° C. to about 1300° C.

11. The method of claim 1, further comprising collecting molecular oxygen at the anode.

12. The method of claim 1, further comprising arranging a conducting structure into a space between the cathode and the anode in electrical contact with the cathode as a preparatory step before applying the electric potential.

13. The method of claim 1, further comprising separating obtained metal from the electrolyte powder through a separation process, the separation process being selected from a group of separation processes, the group comprising: sieving, vibration separation, magnetic separation, electrostatic separation, air classification, sedimenting, and a combination thereof.

14. System for extracting metal and oxygen from powdered metal oxides, the system comprising: an electrolytic cell having a container, a cathode, an anode, and an oxygen-ion-conducting membrane, a solid oxygen ion conducting electrolyte powder, and a power supply, wherein the cathode and the anode are arranged at a distance to each other on the container to form a receiving space, wherein the membrane is arranged between the cathode and the anode and contacts the anode, wherein the electrolytic powder is provided in the receiving space in communication with the cathode and the membrane, wherein the power supply is connectable to the cathode and the anode to selectively apply an electric potential across the cathode and the anode, wherein the system is adapted for reducing at least one respective metallic species of at least one metal oxide of feedstock mixed into and surrounded by the electrolyte powder by applying the electric potential, wherein the potential is greater than the dissociation potential of the at least one metal oxide and less than the dissociation potential of the solid electrolyte powder and the membrane.

15. The system of claim 14, wherein the electrolyte powder comprises at least one of a group of materials, the group consisting of rare earth or alkaline earth-doped zirconia-, ceria-, hafnia-, and thoria-based oxides.

16. The system of claim 14, wherein the solid electrolyte powder comprises mixed oxygen ion electronic conductors.

17. The system of claim 14, wherein the oxygen ion-conducting membrane is selected from a group of materials, the group comprising rare earth or alkaline earth-doped zirconia-, ceria-, hafnia-, and thoria-based oxides, in particular yttria-stabilized zirconia.

18. The system of claim 14, further comprising a conducting structure, in particular pins and/or a wire mesh, in the receiving space between the cathode and the anode in electrical contact with the cathode.

19. The system of claim 14, further comprising an array of anodes, in particular capillary anodes, extending in direction of the cathode.

20. The system of claim 18 and 19, wherein the conducting structure comprises at least one wire mesh, wherein the capillary anodes are at least partially surrounded by mesh cells.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0042] In the following, the attached drawings are used to illustrate exemplary embodiments in more detail. The illustrations are schematic and not to scale. Identical reference numerals refer to identical or similar elements. They show:

[0043] FIG. 1 a simplified sectional view of the system in an embodiment of the system,

[0044] FIG. 2 a simplified sectional view of the system in another embodiment of the system, and

[0045] FIG. 3 a method in a block-oriented, schematic view.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0046] FIG. 1 shows a system 2 for extracting metal and oxygen from powdered metal oxides. The system 2 has an electrolytic cell 4, which comprises a cathode metal plate 6, an insulating bottom plate 8, a solid oxide membrane plate 10 and in electrical contact with an anode current collector 12. The cathode 6, the anode 12 and the bottom plate 8 form a container. Metal pins 14 are in direct contact with the cathode 6 and protrude towards the anode 12.

[0047] In a receiving space 16 between the cathode 6 and the membrane 10 a metal oxide powder 18 is arranged and surrounded by solid electrolyte powder 20. The metal oxide powder 18 and the electrolyte powder 20 are mixed, such that the spaces between particles of the metal oxide powder 18 are filled with the electrolyte powder 20. For this, the mean particle size of the metal oxide powder 18 clearly exceeds the mean particle size of the electrolyte powder 20.

[0048] A power supply 22 is connected to the anode 6 and the cathode 12. It is designed to apply an electric potential between the anode 6 and the cathode 12. Resultingly, metal oxide in the metal oxide powder 18 is reduced to metal and molecular oxygen is collected at the anode 12. During this process, conducting paths for oxygen ions are used, which are created by the electrolyte powder 20 between the individual particles of the metal oxide powder 18, are used. Due to the pins 14 extending towards the anode 12, the mean distance between the cathode 6 and the anode 12 is reduced.

[0049] The reduced metal powder produced as result of the reduction remains in the receiving space 16. After the electrolysis the mixture of the electrolytic powder and the metal powder is removed from the electrolytic cell 4. The metal and the electrolyte powder 20 are separated from each other, and the solid electrolyte powder can be re-used for the next batch of electrolysis with a new load of metal oxide powder 18.

[0050] FIG. 2 shows an electrolytic cell 24 with a modified design. Here, a cathode 26 is formed as a container and includes side walls 28 and a bottom plate 30 and an array of solid oxide membrane anodes 32, each of which is shaped as a one end closed tube with a current collector 34 inside. The membrane anodes 32 are created by coating anodes with the respective membrane material.

[0051] A wire mesh structure 36 is connected to the cathode 26 and partially fills a space between the anodes 32 and the cathode 26 to reduce the average distance between the anodes 32 and elements that provide the cathodic potential. The remaining space between the anodes 32 is filled with a mixture of the metal oxide powder 18 to be reduced and the solid electrolyte powder 20. As in the previous embodiment, the average particle size of the electrolyte powder is clearly lower than the average particle size of the metal oxide powder. Thus, the electrolytic powder thereby fills the gaps between the particles of the metal oxide 18 and provides a conducting path for oxygen ions produced as a result of the reduction towards the solid oxide membrane.

[0052] Upon applying the cell potential between the anodes 32 and the cathode 28, molecular oxygen is collected at the anodes 32, and the reduced metal powder produced as result of the reduction is available within the volume of the cathode 28. As described regarding the previous embodiment, the metal powder can be separated after the electrolysis and the electrolyte powder is reusable.

[0053] FIG. 3 shows a method for extracting metal and oxygen from powdered metal oxides in an electrolytic cell, comprising a container, a cathode, an anode, and an oxygen-ion-conducting membrane. The method comprises providing 38 a solid oxygen ion conducting electrolyte powder into a container, providing 40 a feedstock comprising at least one metal oxide in powdered form into the container, applying 42 an electric potential across the cathode and the anode, the cathode being in communication with the electrolyte powder and the anode being in communication with the membrane in communication with the electrolyte powder, such that at least one respective metallic species of the at least one metal oxide is reduced at the cathode and oxygen is oxidized at the anode to form molecular oxygen. The potential across the cathode and the anode is greater than the dissociation potential of the at least one metal oxide and less than the dissociation potential of the solid electrolyte powder and the membrane. The electrolyte powder and the feedstock may be mixed 44 before or after providing them. During the reduction process, molecular oxygen can be collected 46 at the anode.

[0054] As a preparatory step, a conducting structure, such as a wire mesh, can be arranged 48 into a space between the cathode and the anode in electrical contact with the cathode before applying the electric potential. After the electrolysis process, obtained metal is separated 50 from the electrolyte powder through a separation process.

Reference Numerals

[0055] 2 system [0056] 4 electrolytic cell [0057] 6 cathode [0058] 8 bottom plate [0059] 10 membrane [0060] 12 anode [0061] 14 metal pin [0062] 16 receiving space [0063] 18 metal oxide powder (feedstock) [0064] 20 electrolyte powder [0065] 22 powder supply [0066] 24 electrolytic cell [0067] 26 cathode [0068] 28 side wall [0069] 30 bottom plate [0070] 32 membrane anode [0071] 34 current collector [0072] 36 wire mesh [0073] 38 providing electrolyte [0074] 40 providing feedstock (metal oxide powder) [0075] 42 applying electric potential [0076] 44 mix electrolyte and feedstock [0077] 46 collect oxygen [0078] 48 arrange conducting structure [0079] 50 separate metal