Eltech Systems Corporation

Diamond Shamrock Corporation

Oxytech Systems, Inc.

James R Brannan

Anthony J Vaccaro

Jeries I Bishara

Jean M Hinden

Irving Malkin

James J Stewart

Anthony R Sacco

Roland J Horvath

Andrew S Bean

Gerald R Pohto

Richard L Romine

Donald J Groszek

Mark L Arnold

Lawrence J Gestaut

Daniel W Gibbons

Janet S Gregg

Claude M Brown

John P Healy

Richard A Kus

A process is disclosed, as well as apparatus useful therefor, for continuously electroplating a strip of reticulated foam using multiple electroplating zones that each contain electroplating bath. In each zone there is a cathode and an anode. In at least one electroplating zone there is an insoluble anode, typically as the sole anode. In some of the electroplating zones soluble anodes may be used. As a first cathode, there can be provided a cathode roll outside of the electroplating bath. The reticulated foam is guided in the bath past the anodes, as well as past cathodes, e.g., including a cathode roll which may be positioned outside of the bath. The resulting electroplated foam emerging from the bath has an improved electroplate weight distribution and the process achieves enhanced efficiencies and economies of operation.

Continuously electroplated foam of improved weight distribution

Methods, and various apparatus therefor, are disclosed for the electrolytic treatment of an acidic solution. Generally the method comprises: (a) providing an electrolytic cell, the cell comprising: (i) an anode chamber and an anode therein; (ii) a cathode chamber and a cathode therein; and (iii) a diaphragm. Usually the diaphragm is of a non-isotropic fibrous mat comprising 5-70 weight percent organic halocarbon polymer fiber in adherent combination with about 30-95 weight percent of finely divided inorganic particulate impacted into said fiber during fiber formation, the diaphragm having a weight per unit of surface area of about 3-12 kilograms per square meter. The method can continue by (b) introducing the acidic solution into the cell; (c) impressing a current on the anode and the cathode causing the migration of ions through the diaphragm; and (d) recovering a product of the electrolytic treatment from the anode chamber, or the cathode chamber, or from both chambers. In one method, the acidic solution is a cell bath circulated to the anode chamber, while rinse solution downstream of the cell bath is circulated to the cathode chamber. The method, and apparatus therefor, are particularly applicable to the recovery of hexavalent chromium from a dilute chromium electroplating rinse solution.

Electrolytic treatment of an electrolytic solution

There is now disclosed a method of restoring a used article utilized in electrolysis, such as in a chlor-alkali cell. The used article is usually the cell diaphragm, but may be a cell electrode, particularly when it is in assembly with the cell diaphragm. The restoration method involves treating the article, typically in place in the cell, but which may be removed from the cell, by soaking in a treating composition containing most always hydrochloric acid and corrosion inhibitor. The article after treatment may be baked at elevated temperature. When baking is utilized, it can come before soaking. With or without baking, the article may or may not be involved in a wetting step. Where the restoration involves an article utilized in a chlor-alkali cell, the restoration can readily reduce the problem of hydrogen in the chlorine product produced. Such treatment can also lead to reduced cell voltage as well as reduced cell anolyte level.

Electrolysis cell diaphragm reclamation

Compressed diaphragm and electrolytic cell

There is now provided an improved manufacturing method for increasing the active material filling density in a small DTR reticulated nickel sheet. The nickel sheet has desirable physical properties such as resistance to breakage and crushing, in repeated bending. This resistance can be for both the surface area and the central area, in the thickness direction of the sheet. Such small DTR sheet has not previously been preferred as a battery electrode material because of a smaller filling density using conventional methods. There is now provided a battery electrode having high filling density of active material, high utilization rate of the impregnated active material and high capacity density with long life. Furthermore, a method of producing such small DTR of reticulated nickel sheet in a continuous and economical manner is disclosed.

High density, high capacity battery electrode

A method, and apparatus therefor, for the electrolytic treatment of an acidic solution which comprises: (a) providing an electrolytic cell, the cell comprising: (i) an anode chamber and an anode therein; (ii) a cathode chamber and a cathode therein; (iii) a diaphragm of a non-isotropic fibrous mat comprising 5-70 weight percent organic halocarbon polymer fiber in adherent combination with about 30-95 weight percent of finely divided inorganic particulate impacted into said fiber during fiber formation, the diaphragm having a weight per unit of surface area of about 3-12 kilograms per square meter; (b) introducing the acidic solution into the cell; (c) applying a DC voltage between the anode and the cathode causing the migration of ions through the diaphragm; and (d) recovering a product of the electrolytic treatment from the anode chamber, or the cathode chamber, or from both chambers. The method, and apparatus therefor, are particularly applicable to the recovery of hexavalent chromium from a dilute chromium electroplating rinse solution.

Electrolytic cell apparatus

In the electroplating of certain metals, such as zinc, a metal build-up in the electroplating bath occurs due to a higher anode efficiency than cathode efficiency, in the cell, and also due to chemical dissolution of the anode in the electroplating bath. An electrowinning cell is provided to remove metal from the electroplating bath. The electrowinning cell is operated with a current sufficient to remove metal from the bath substantially equal to that chemically dissolved into the bath as well as the build-up due to the difference in the anodic and cathodic efficiencies.

Process for electroplating

The present invention resides in the discovery that a strip of reticulated foam which is semi-conductive can be continuously electroplated, utilizing a cathode roll which is positioned, in a first electroplating zone, outside of the electroplating bath. An anode is immersed in the electroplating bath. The strip of reticulated foam is first introduced into the electroplating bath and travels in the direction from the anode to the cathode roll prior to contacting the cathode roll. In this way, the strip achieves a partial plate at the anode which provides a current path between the anode and the cathode roll effective for sustaining the plating reaction in said first electroplating zone.

Continuous electroplating of conductive foams

A cathode for the electrolysis of brine for the production of chlorine and caustic soda, whereby chlorate ions are produced, comprises a coating of e.g. Nickel alloyed with a metallic sacrificial component, the latter being leached out by a soltuion of sodium hydroxide. The remaining sodium hydroxide within the pores of the leached nickel coating is transformed into iron hydroxide upon application of an iron salt onto the nickel coating. The iron hydroxide acts as a suppressor for the excessive formation of chlorate ions in the caustic soda solution of the electrolysis cell.

Cathode for electrolysis cell

This invention relates to the art of electrowinning and, more particularly, to a process for recovering zinc which is leached from an alloy coating of nickel and zinc which has previously been deposited on cathodes of an electrolytic cell used in the electrolysis of alkali metal halides. Further, a method of utilizing the recovered zinc for control of the zinc content of the nickel-zinc plating solution is disclosed.

Method for recovery and use of zinc from a leach solution

An active metal coating which lowers the hydrogen discharge overpotential at the cathode in the electrolysis of aqueous alkali metal halide solutions is deposited on the cathode tubes of a cathode can of an electrolysis cell without the removal of the tubes from the can. Plating solution and anodes of plating metal are placed inside a cathode can and the components are electrically connected so as to deposit an active coating onto the cathode tubes. The plating metal is preferably an alloy of nickel and zinc and the process involves the final step of leaching the zinc component of the alloy deposit from the plated cathode tubes to provide a porous, active nickel surface which results in a reduction of the hydrogen discharge overpotential for the electrolysis of alkali metal halides, particularly sodium chloride.

Method of in situ plating of an active coating on cathodes of alkali

An active coating comprised of a mixture of palladium oxide and zirconium dioxide deposited on a metal substrate selected from a group consisting of iron, nickel, cobalt and alloys thereof, results in a lower hydrogen overpotential at the cathode in the electrolysis of aqueous alkali metal halide solutions. Salts of the component metals of the coating are deposited on the cathode surface preferably by painting. The coating metals are then converted to the corresponding metal oxides through the heating of the coating and substrate to 300.degree. to 600.degree. C in an oxidizing atmosphere such as air or oxygen. The coating results in a lowering of the hydrogen discharge overpotential at the cathode surface of about 50 to 100 millivolts as compared with the hydrogen discharge overpotential for the mild steel substrate commonly used as a cathode in electrolysis cells.

Coated cathode for electrolysis cells

A cathode adapted for the electrolysis of water or an aqueous solution of an alkali metal halide salt because it gives prolonged lowering of hydrogen overvoltage is provided by an electrically conductive substrate bearing on its surface a coating produced by melt spraying an admixture of particulate nickel or cobalt and particulate aluminum and then leaching out the aluminum.

Growing community of inventors

Perry, OH, United States of America

James R Brannan