Method of production of metal particles through electrolysis

• US 7,273,537 B2
• Filed: 04/24/2003
• Issued: 09/25/2007
• Est. Priority Date: 09/12/2002
• Status: Active Grant

• Current Assignee: Zinc8 Energy Solutions, Inc.
• Original Assignee: Teck Cominco Metals Ltd.
• Inventors: Smedley, Stuart I., Des Jardins, Stephen R., Gulino, Ronald, Novkov, Donald James, De Tezanos Pinto, Martin
• Primary Examiner(s): King; Roy
• Assistant Examiner(s): Leader; William T.
• Application Number:
  US10/424,571
• Publication Number:
  US 20050098442A1
• Time in Patent Office: 1,615 Days
• Field of Search: 205/74
• US Class Current: 205/74
• CPC Class Codes: C25C 5/02 from solutions
• CPC Class Codes: C25C 7/06 Operating or servicing

Abstract

A method of producing metal particles through electrolysis. A cathode having a plurality of active zones on a surface thereof is at least partially immersed in a reaction solution. The cathode is spaced from an anode also at least partially immersed in the reaction solution. A voltage potential is applied between the anode and cathode. Metal particles form on the active zones of the cathode. In order to promote the formation of good quality particles, a turbulent flow of the solution is maintained past one or more the active zones, and the current density in the active zones is maintained greater than about 5 kA/m². The particles may be dislodged from the cathode after they have achieved a desired size.

Claims

1. A method of producing zinc particles having low superficial density and high surface area, suitable for use in metal/air fuel cells, comprising:

containing a solution including dissolved zinc;

maintaining the solution at a temperature between about 0 and about 100 degrees Centigrade;

immersing an anode at least partly in the solution;

immersing a cathode at least partly in the solution, the cathode having a plurality of active zones separated from each other by an insulator, each active zone having an area less than about 0.04 square mm, said active zones electrically coupled to a conductor and spaced apart by less than about 2.0 mm;

maintaining turbulent flow of the solution past one or more of the active zones;

applying an electric potential across the anode and cathode sufficient to grow a plurality of lobes of the zinc at each active zone; and

ceasing growth of the zinc lobes when the plurality of lobes at each active zone bond together to form a multi-lobed particle, wherein the particle at each active zone is grown initially from lobes.

2. The method of claim 1 wherein the solution has a dissolved zinc molarity between about 0.55 M and about 1.25 M.

3. The method of claim 1 wherein the solution comprises a dissolved electrolyte having an initial concentration between about 25 and about 55 weight percent.

4. The method of claim 1 wherein the temperature is maintained between about 20 and about 40 degrees C.

5. The method of claim 1 wherein the growing step further comprises applying an electric potential across the anode and cathode sufficient to maintain a current density in a range between about 10 kA/m² and about 40 kA/m² in each of the active zones.

6. The method of claim 5 further comprising:

removing the multi-lobed particles from the cathode;

sieving the multi-lobed particles to select particles of a minimum size;

colliding the multi-lobed particles to separate weakly bonded lobes; and

sieving the collided particles to collect multi-lobed particles suitable for use in the fuel cells.

7. The method of claim 6 wherein the minimum size is a length of about 0.38 mm.

8. The method of claim 6 wherein the colliding step further comprises circulating the selected particles through a hydraulic circuit.

9. The method of claim 8 wherein the hydraulic circuit contains a KOH solution.

10. The method of claim 6 wherein the second sieving step collects multi-lobed particles having a minimum length of about 0.38 mm.

11. The method of claim 1 further comprising adding bismuth to the solution.

12. The method of claim 11 wherein the bismuth is added as Bi₂O₃ in a proportion equivalent to about 400 ppm Bi₂O₃ to about 40 liters of the solution.

13. The method of claim 1 further comprising adding indium to the solution.

14. The method of claim 13 wherein the indium is added as In(OH)₃ in a proportion equivalent to about 250 ppm In(OH)₃ to about 40 liters of the solution.

15. A process for producing coherent, mechanically strong zinc particles suitable for use in metal/air fuel cells, comprising:

a step for containing a solution including dissolved zinc, the solution having a molarity between about 0.55M and about 1.25M;

a step for maintaining the solution at a temperature between about 20 and about 40 degrees Centigrade;

a step for immersing an anode at least partly in the solution;

a step for immersing a cathode at least partly in the solution, the cathode having a plurality of active zones separated from each other by an insulator, each active zone having an area less than about 0.04 square mm, said active zones electrically coupled to a conductor and spaced apart by less than about 2.0 mm;

a step for maintaining a turbulent flow of the solution past one or more of the active zones;

a step for applying an electric potential across the anode and cathode sufficient to grow a plurality of lobes of the zinc at each active zone; and

a step for ceasing growth of the zinc lobes when the plurality of lobes at each active zone bond together to form a multi-lobed particle, wherein the particle at each active zone is grown initially from lobes.

16. The process of claim 15 wherein the solution has an initial concentration of the dissolved zinc between about 25 and about 55 weight percent.

17. The method of claim 15 wherein the growing step further comprises applying an electric potential across the anode and cathode sufficient to maintain a current density in a range between about 10 kA/m₂ and about 40 kA/m₂ in each of the active zones.

18. The method of claim 17 further comprising:

a step for removing the multi-lobed particles from the cathode;

step for sieving the multi-lobed particles to select particles of a minimum size;

a step for colliding the multi-lobed particles to separate weakly bonded lobes; and

a step for sieving the collided particles to collect multi-lobed particles suitable for use in the fuel cells.

19. The method of claim 18 wherein the minimum size is a length of about 0.38 mm.

20. The method of claim 18 wherein the colliding step further comprises circulating the selected particles through a hydraulic circuit.

21. The method of claim 20 wherein the hydraulic circuit contains a KOH solution.

22. The method of claim 18 wherein the second sieving step collects particles having a minimum length of about 0.38 mm.

23. The method of claim 15 further comprising a step for adding bismuth to the solution.

25. The method of claim 15 further comprising a step for adding indium to the solution.

26. The method of claim 25 wherein the indium is added as In(OH)₃ in a proportion equivalent to about 250 ppm In(OH)₃ to about 40 liters of the solution.

24. The method of 23 wherein the bismuth is added as Bi₂O₃ in a proportion equivalent to about 400 ppm Bi₂O₃ to about 40 liters of the solution.