Strengthened fiberous electrochemical cell diaphragm and a method for making

Claim 1

A method for making a porous asbestos diaphragm for use in an electrochemical process including the steps of: (1) slurrying a mixture of fibers including primarily asbestos fibers in an aqueous solution of at least one of NaCl within a concentration range of from about 5 percent of saturation to about 50 percent of saturation and NaOH within a concentration range of from about 4 weight percent to about 50 weight percent; (2) drawing the slurry through a porous surface; (3) depositing the fibers upon the porous surface to a desired thickness; (4) drawing a substantial quantity of wash water through the diaphragm; (5) dissolving a basic compound selected from a group consisting of (NH 4 ) 2 CO 3 , NH 4 OH, KHCO 3 , K 2 CO 3 , Na 2 CO 3 , NaHCO 3 , weak caustic and brine in water to form a basic solution; (6) drawing the basic solution through the diaphragm at least until a pH of between 7 and 11 is achieved generally uniformly throughout the diaphragm, (7) drawing an aqueous solution of ammonium zirconium carbonate within a range of concentration of between about 3 weight percent and about 50 weight percent through the diaphragm to thoroughly saturate the diaphragm; (8) withdrawing excess ammonium zirconium carbonate solution from the diaphragm; (9) heating the diaphragm to remove a substantial portion of water remaining in the diaphragm; and (10) further heating the diaphragm to between 110° C. and 400° C. to remove further moisture and to oxidize the ammonium zirconium carbonate to ZrO 2 and combustion by-products.

Claim 2

A method for making a porous asbestos diaphragm for use in an electrochemical process including the steps of: (1) slurrying a mixture of fibers including primarily asbestos fibers in an aqueous solution of at least one of NaCl within a concentration range of from about 5 percent of saturation to about 50 percent of saturation and NaOH within a concentration range of from about 4 weight percent to about 50 weight percent; (2) drawing the slurry through a porous surface; (3) depositing the fibers upon the porous surface to a desired thickness; (4) drawing a substantial quantity of wash water through the diaphragm; (5) dissolving a basic compound selected from a group consisting of (NH 4 ) 2 CO 3 , NH 4 OH, KHCO 3 , K 2 CO 3 , Na 2 CO 3 , NaHCO 3 , weak caustic and brine in water to form a basic solution; (6) drawing the basic solution through the diaphragm at least until a pH of between 7 and 11 is achieved generally uniformly throughout the diaphragm, (7) drawing an aqueous solution of ammonium zirconium carbonate within a range of concentration of between about 3 weight percent and about 50 weight percent through the diaphragm to thoroughly saturate the diaphragm; (8) withdrawing excess ammonium zirconium carbonate solution from the diaphragm; (9) heating the diaphragm to remove a substantial portion of water remaining in the diaphragm; and (10) further heating the diaphragm to between 110° C. and 400° C. to remove further moisture and to oxidize the ammonium zirconium carbonate to ZrO 2 and combustion by-products.

Claim 6

A method for making a porous asbestos diaphragm for use in an electrochemical process including the steps of: (1) slurrying a mixture of fibers including primarily asbestos fibers in an aqueous solution of at least one of NaCl within an NaCl concentration range of from about 5 percent of saturation to about 50 percent of saturation and NaOH within an NaOH concentration range of from about 4 weight percent to about 50 weight percent; (2) drawing the slurry through a porous surface; (3) depositing the fibers upon the porous surface to a desired thickness; (4) drawing a substantial quantity of wash water through the diaphragm; (5) drawing an aqueous solution of zirconium acetate within a range of concentration of between about 3 weight percent to about 50 weight percent through the diaphragm to thoroughly saturate the diaphragm; (6) withdrawing excess zirconium acetate solution from the diaphragm; (7) heating the diaphragm to remove a substantial portion of water remaining in the diaphragm; and (8) further heating the diaphragm to between 100° C. and 400° C. to remove further moisture and to oxidize the zirconium acetate to ZrO 2 and combustion by-products.

Claim 7

A method for making a porous asbestos diaphragm for use in an electrochemical process including the steps of: (1) slurrying a mixture of fibers including primarily asbestos fibers in an aqueous solution of at least one of NaCl within an NaCl concentration range of from about 5 percent of saturation to about 50 percent of saturation and NaOH within an NaOH concentration range of from about 4 weight percent to about 50 weight percent; (2) drawing the slurry through a porous surface; (3) depositing the fibers upon the porous surface to a desired thickness; (4) drawing a substantial quantity of wash water through the diaphragm; (5) drawing an aqueous solution of zirconium acetate within a range of concentration of between about 3 weight percent to about 50 weight percent through the diaphragm to thoroughly saturate the diaphragm; (6) withdrawing excess zirconium acetate solution from the diaphragm; (7) heating the diaphragm to remove a substantial portion of water remaining in the diaphragm; and (8) further heating the diaphragm to between 100° C. and 400° C. to remove further moisture and to oxidize the zirconium acetate to ZrO 2 and combustion by-products.

Claim 11

A method for making a porous diaphragm for use in an electrochemical process comprising the steps of: (1) slurrying a mixture of substantially asbestos fibers in an aqueous solution containing zirconium acetate in a composition range of between about 5 percent and 50 weight percent; (2) maintaining a slurry pH of not less than 2 nor more than 5; (3) passing the slurry through a porous surface to deposit the fibers upon the porous surface to a desired thickness; (4) withdrawing excess zirconium containing solution from the diaphragm; (5) removing a substantial portion of water remaining in the diaphragm; and (6) heating the diaphragm to between 100° C. and 400° C. to remove additional moisture and to convert a substantial portion of the zirconium compound to ZrO 2 .

Claim 12

A method for making a porous diaphragm for use in an electrochemical process comprising the steps of: (1) slurrying a mixture of substantially asbestos fibers in an aqueous solution containing zirconium acetate in a composition range of between about 5 percent and 50 weight percent; (2) maintaining a slurry pH of not less than 2 nor more than 5; (3) passing the slurry through a porous surface to deposit the fibers upon the porous surface to a desired thickness; (4) withdrawing excess zirconium containing solution from the diaphragm; (5) removing a substantial portion of water remaining in the diaphragm; and (6) heating the diaphragm to between 100° C. and 400° C. to remove additional moisture and to convert a substantial portion of the zirconium compound to ZrO 2 .

Claim 14

A method for making a porous diaphragm for use in an electrochemical process comprising the steps of: (1) slurrying a mixture of substantially asbestos fibers in an aqueous solution containing ammonium zirconium carbonate in a composition range of between about 5 weight percent and 50 weight percent; (2) maintaining a slurry pH of not less than 7 nor more than 11 by adding a basic compound selected from the group consisting of (NH 4 ) 2 CO 3 , NH 4 OH, NaHCO 3 , Na 2 CO 3 , NH 4 HCO 3 , K 2 CO 3 and KHCO 3 to the slurry; (3) passing the slurry through a porous surface to deposit the fibers upon the porous surface to a desired thickness; (4) withdrawing excess zirconium containing solution from the diaphragm; (5) removing a substantial portion of water remaining in the diaphragm; and (6) further heating the diaphragm to between 100° C. and 400° C. to remove additional moisture and to convert the zirconium containing compound to ZrO 2 .

Claim 15

A method for making a porous diaphragm for use in an electrochemical process comprising the steps of: (1) slurrying a mixture of substantially asbestos fibers in an aqueous solution containing ammonium zirconium carbonate in a composition range of between about 5 weight percent and 50 weight percent; (2) maintaining a slurry pH of not less than 7 nor more than 11 by adding a basic compound selected from the group consisting of (NH 4 ) 2 CO 3 , NH 4 OH, NaHCO 3 , Na 2 CO 3 , NH 4 HCO 3 , K 2 CO 3 and KHCO 3 to the slurry; (3) passing the slurry through a porous surface to deposit the fibers upon the porous surface to a desired thickness; (4) withdrawing excess zirconium containing solution from the diaphragm; (5) removing a substantial portion of water remaining in the diaphragm; and (6) further heating the diaphragm to between 100° C. and 400° C. to remove additional moisture and to convert the zirconium containing compound to ZrO 2 .

Claim 16

A method for preparing a diaphragm for use in an electrochemical cell, the diaphragm consisting essentially of inorganic asbestos fibers, comprising the steps of: (1) slurrying a quantity of said fibers in an aqueous solution containing zirconium acetate in a concentration range of between 5 weight percent and 35 weight percent; (2) maintaining a slurry pH of between 2 and 5 by introducing required quantities of an acid into the slurry; (3) drawing the slurry through a porous surface to deposit the fibers upon the porous surface to a desired thickness thereby forming the diaphragm; (4) withdrawing excess solution containing the zirconium compound from the diaphragm; and (5) heating the diaphragm to remove water remaining in the diaphragm and to convert zirconium remaining in the diaphragm to ZrO 2 .

Claim 17

A method for preparing a diaphragm for use in an electrochemical cell, the diaphragm consisting essentially of inorganic asbestos fibers, comprising the steps of: (1) slurrying a quantity of said fibers in an aqueous solution containing zirconium acetate in a concentration range of between 5 weight percent and 35 weight percent; (2) maintaining a slurry pH of between 2 and 5 by introducing required quantities of an acid into the slurry; (3) drawing the slurry through a porous surface to deposit the fibers upon the porous surface to a desired thickness thereby forming the diaphragm; (4) withdrawing excess solution containing the zirconium compound from the diaphragm; and (5) heating the diaphragm to remove water remaining in the diaphragm and to convert zirconium remaining in the diaphragm to ZrO 2 .