Anodic structure for mercury cathode electrolytic cells description of the invention

• US 20040074765A1
• Filed: 08/05/2003
• Published: 04/22/2004
• Est. Priority Date: 03/27/2001
• Status: Active Grant

• Current Assignee: De Nora Elettrodi S.p.a.
• Original Assignee: De Nora Elettrodi S.p.a.
• Inventors: Meneghini, Giovanni
• Granted Patent: US 7,214,296 B2
• Time in Patent Office: Days
• US Class Current: 204/273
• CPC Class Codes: C25B 11/02 characterised by shape or form
• CPC Class Codes: Y10T 29/53204 Electrode

Abstract

Object of the invention is an anodic structure for mercury cathode cells for the industrial electrolysis of sodium chloride. The new structure is constituted by a grid array comprising a multiplicity of vertically disposed and mutually parallel titanium blades, covered by an electrocatalytic coating specific for the discharge of chlorine. The ratio between the thickness and the height of the blades is comprised between 1:16 and 1:100 and the ratio between the surface of free passage between the blades and the projected surface is comprised between 15:17 and 25:30. The new grid array is perpendicularly fixed to new or existing frames having the function of mechanical support and current conduction to the grid array. Scope of the invention is simultaneously reducing the energetic consumption of the cell and the costs for restoring the exhausted electrocatalytic coating.

Claims

1. An anode for chlorine evolution in a mercury cathode chlor-alkali electrolytic process, consisting in a current-distributing frame and a grid array of titanium or titanium alloy or other valve metal or valve metal alloy comprising a multiplicity of generally parallel blades fixed to a multiplicity of supporting elements, the blades having a thickness comprised between 0.3 and 0.5 millimetres and a height comprised between 8 and 20 millimetres, the distance between one blade and the next being comprised between 1.5 and 2.5 millimetres.

2. The anode of claim 1 wherein the terminal longitudinal parts of the blades define a plane having a tolerance not higher than 0.2 millimetres.

5. The anode of one of claims 1 to 5 wherein at least the main vertical surfaces of the blades are provided with an electrocatalytic coating for chlorine evolution.

6. The anode of claim 5 wherein the upper surface of the grid array comprises hydrodynamic means for the generation of convective motions.

7. The anode of one of one of claims 5 or 6 wherein the supporting elements are made by rods.

8. The anode of one of claims 5 or 6 wherein the blades have a height of 12 millimetres, the gap between adjacent blades is 2.0 millimetres, and the supporting elements are rods of diameter comprised between 2 and 3 millimetres orthogonally fixed to the upper surface of said blades.

9. The anode of one of claims 5 to 8 wherein the multiplicity of blades is fixed to the multiplicity of supporting elements by welding.

14. Use of an anode of claims 1 to 9 in a mercury cathode sodium chloride cell for the production of chlorine.

3. An anode for chlorine evolution in a mercury cathode chlor-alkali electrolytic process, consisting in a current-distributing frame and a grid array of titanium or titanium alloy or other valve metal or valve metal alloy comprising a multiplicity of generally parallel blades fixed to a multiplicity of supporting elements, the blades having a thickness comprised between 0.2 and 1 millimetres and a height comprised between 8 and 20 millimetres, the distance between one blade and the next being comprised between 1.5 and 2.5 millimetres, wherein the terminal longitudinal parts of the blades are mechanically machined to define a plane having a tolerance not higher than 0.2 millimetres.

4. The anode of claim 3 wherein the blades have a thickness comprised between 0.3 and 0.5 millimetres.

10. Method for the production of the anode of one of claims 4 to 9 comprising the activation of the blades with said electrocatalytic coating, the assemblage of the grid array to the frame, and a final mechanical machining of the surface of said grid array to be faced to the mercury cathode suited to ensure the planarity of said surface.

11. The method of claim 10 wherein said mechanical machining is a grinding.

12. Method for the reactivation of the anode of one of claims 4 to 9, comprising mechanically removing a portion of said blades in correspondence of which said electrocatalytic coating is exhausted.

13. The method of claim 12 wherein said mechanical removal is carried out by grinding.

15. Anode for chlorine evolution comprising the distinctive elements of the description and the figures.