Eltech Systems Corporation

Zoilo J Colon

Kenneth L Hardee

Lynne M Ernes

Richard C Carlson

Barry L Martin

Eric J Rudd

Mark L Arnold

Rudolf C Matousek

Gary F Wyman

Joseph J Chance

The present invention pertains to electrolytic diaphragm cells, particularly for the electrolysis of brine to produce chlorine and caustic. The innovation resides generally in the discovery that electrolytic cell operation can be desirably enhanced by compressing the diaphragm between anode and cathode. This compression of the diaphragm reduces the diaphragm thickness from an original thickness, e.g., from an original thickness of a diaphragm freshly deposited on a cathode. The reduced thickness of the diaphragm provides for cell operation that is less than zero gap operation. By maintaining the diaphragm under compression and in a reduced thickness, the cell operates with a narrower interelectrode gap and consequently at a desirably reduced cell voltage.

Diaphragm cell

A method is now utilized for stripping costly electrocatalytic coatings from valve metal substrates while maintaining excellent integrity of the substrate metal. The removed metal may also be conveniently recovered. A molten salt bath of alkali metal hydroxide and alkali metal salt of an oxidizing agent is employed. Careful electrode to bath contact times and bath temperatures are observed. Additionally, a dilute mineral acid rinse and water rinse, with scrubbing in one of the rinses follows such molten salt bath contact for the electrode. Solids recovered from the rinses are combined.

Molten salt stripping of electrode coatings

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Chardon, OH, United States of America

Zoilo J Colon