Abstract: A process for the electrolytic recovery of metals from solutions containing metal ions and fluorides and/or anionic flurocomplexes in diaphragmless cells wherein the deposition of the metals at the cathodes and the oxygen evolution at the anodes is effected, the improvement comprising the use of insoluble anodes made of sintered powders of doped tin dioxide optionally provided with coating of zirconyl phosphate and metal oxides which prevents the deposition of metal oxides on the anode surface and catalyze the oxygen evolution reaction.

Abstract: The present invention relates to metal anodes for oxygen evolution from solutions containing fluorides or artionic fluorocomplexes such as tetrafluoroborates and hexafluorosilicates, the anodes having a metal substrate or matrix selected in the group comprising nickel-copper alloys with a copper content in the range of 2.5 and 30% by weight, tungsten or tantalum, niobium or titanium, combinations thereof or alloys of the same with palladium, nickel or yttrium. The anodes further comprise electrocatalytic compounds for oxygen evolution dispersed in the metal matrix. In the case of nickel- copper alloys, useful electrocatalytic compounds are cerium or tin dioxides, with suitable additives, while for tungsten, cobalt added with nickel, iron, copper or palladium may be used.

Abstract: In a process for the electrolysis of alkali metal chloride conducted in a cell comprising a porous, gas and liquid permeable anode and a porous, gas and liquid permeable cathode separated by an ion exchange polymeric membrane impervious to the hydrodynamic flow, wherein the electrodes are in contact or in any way close to the membrane surface in order to reduce the interelectrodic gap, the insertion of a thin porous sheet, fluid permeable and highly hydrophilic, between the membrane and the cathode surfaces, allows for the considerable reduction of the cell voltage.

Abstract: An anode comprising an electroconductive substrate, whose external surface at least is selected from the group consisting of vanadium, niobium, tantalum and tungsten, alloys of said metals with each other and alloys of said metals with at least one metal selected from the group consisting of metals of groups IIIB and IV of the Periodic Table, lanthanides, actinides, the external surface having a corrosion resistant electrocatalytic coating of at least one member of the group consisting of noble metals and alloys thereof, noble metal oxides and non-noble metal oxieds, characterized in that the coating also contains at least one compound of an element selected from the group consisting of arsenic, antimony, bismuth, tin, for metal recovery from acid solutions based on fluodide-containing complex anions and an electrochemical cell.

Abstract: A cell is provided having an anode and cathode separated by an ion permeable membrane or diaphragm wherein an electrode layer is bonded to or otherwise embedded in on at least one and usually to both sides of the membrane. Polarity is imparted to a bonded or embedded electrode by pressing a crinkled resiliently compressible fabric against the membrane carrying the electrode layer. This fabric is substantially coextensive with the electrode layer and is constructed so that when compressed it exerts a substantially uniform elastic reaction pressure against the membrane carrying the electrode layer or a pliable foraminous sheet, i.e. screen, interposed between the membrane carrying the electrode layer and the resiliently compressible fabric. The resiliently compressible fabric has the ability of also transmitting pressure laterally so that pressure applied may distribute across the entire area of the layer and tendency to have local areas of too low of too high pressure is minimized or reduced.

Abstract: The present invention relates to an electrolyzer comprising at least an intermediate electrodic structure interposed between two electrodic end-structures, a separate on each side of the intermediate electrodic structure, device for impressing electrolysis current to the electrolyzer and means for feeding electrolytes to and withdrawing electrolysis products from the electrolyzer compartments. The intermediate electrodic structure comprises a current conducting and distributing core (1) of at least one highly conductive metal sheet; a series of substantially parallel, projecting ribs (2, 10) provided or not onto both surfaces of said core (1); a liner (3) on each side of the core (1) and made of a corrosion resistant metal. These liners (3) are formed by cold- or hot-pressing to fit to the ribs (2, 10) in case core ribs are provided, or have parallel ribs (10') fixed thereto in case core (1) has no ribs. The liners (3) have peripheral projecting flanges (4) parallel to the liners.

Abstract: Halogen is produced by electrolyzing an aqueous halide in a specially designed cell. The cell comprises an anolyte chamber and a catholyte chamber separated by a permeable membrane or diaphragm, notably an ion exchange (generally cation exchange) polymer. At least one electrode comprises at least two sections. One section comprises a gas and electrolyte permeable layer, sheet or mat having a catalytic surface, i.e. one having a low overvoltage, (low hydrogen overvoltage if the cathode and low halogen overvoltage if the anode). This layer is spaced from the membrane by a second portion comprising an electroconductive resiliently compressible layer or mat, which is in contact with the membrane on one side thereof, the other side thereof being in contact with the main cathode.This second or spacer section advantageously has an electrode surface having a higher overvoltage than the first electrode surface. Preferably the cathode has the above construction.

Abstract: Anodes made of lead or lead alloys, used for the evolution of oxygen from sulphuric acid solutions, particularly in metal electrowinning processes, are made more catalytic by treating them in an oxidizing bath of hydrated molten salts, in particular comprising highly oxidizing persalts or nitrates, of cobalt, iron and nickel.After treatment, the anodes exhibit an extraordinary low oxygen overvoltage and allow a considerable saving of energy in comparison with untreated anodes.

Abstract: Anodes made of lead or lead alloys, used for the evolution of oxygen from sulphuric acid solutions, particularly in metal electrowinning processes, are made more catalytic by treating them in an oxidizing bath of hydrated molten salts, in particular comprising highly oxidizing persalts or nitrates, of cobalt, iron and nickel.After treatment, the anodes exhibit an extraordinary low oxygen overvoltage and allow a considerable saving of energy in comparison with untreated anodes.

Abstract: An advantageous anodic structure, particularly useful for cathodic protection of metal structures having a large linear extension, is made of an insulated power cable having suitable terminal at least at one end for the electrical connection to the positive pole of the electrical source and of a series of anodic segments distributed over the length of the power cable, coaxial with the cable itself and electrically connected through a leak-proof connection with the conductive core of the insulated power cable without interruption of the core continuity.

Abstract: A cell is provided having an anode and cathode separated by an ion permeable membrane or diaphragm wherein an electrode layer is bonded to or otherwise embedded in on at least one and usually to both sides of the membrane. Polarity is imparted to a bonded or embedded electrode by pressing a crinkled resiliently compressible fabric against the membrane carrying the electrode layer. This fabric is substantially coextensive with the electrode layer and is constructed so that when compressed it exerts a substantially uniform elastic reaction pressure against the membrane carrying the electrode layer or a pliable foraminous sheet, i.e. screen, interposed between the membrane carrying the electrode layer and the resiliently compressible fabric. The resiliently compressible fabric has the ability of also transmitting pressure laterally so that pressure applied may distribute across the entire area of the layer and tendency to have local areas of too low of too high pressure is minimized or reduced.

Abstract: An advantageous anodic structure, particularly useful for cathodic protection of metal structures having a large linear extension, is made of an insulated power cable having suitable terminal at least at one end for the electrical connection to the positive pole of the electrical source and of a series of anodic segments distributed over the length of the power cable, coaxial with the cable itself and electrically connected through a leak-proof connection with the conductive core of the insulated power cable without interruption of the core continuity.

Abstract: Halogen is produced by electrolyzing an aqueous halide in a specially designed cell. The cell comprises an anolyte chamber and a catholyte chamber separated by a permeable membrane or diaphragm, notably an ion exchange (generally cation exchange) polymer. At least one electrode comprises at least two sections. One section comprises a gas and electrolyte permeable layer, sheet or mat having a catalytic surface, i.e. one having a low overvoltage, (low hydrogen overvoltage if the cathode and low halogen overvoltage if the anode). This layer is spaced from the membrane by a second section comprising a thin intermediate electroconductive layer, screen or coating which is in contact with the membrane on one side thereof, the other side thereof being in contact with the main cathode.This second or spacer section advantageously has an electrode surface having a higher overvoltage than the first electrode surface. Preferably the cathode has the above construction.

Abstract: An electrolysis cell comprising a housing containing a plurality of alternating anode units and cathode units and an ion permeable membrane sheet disposed therebetween and having bonded to opposite sides of the membrane sheet a porous anode and a porous cathode, said cathode units comprising a pair of spaced foraminous electrical current cathode distributors of the same polarity forming a space for catholyte therebetween and means for flowing aqueous electrolyte through the catholyte space of the cathode unit and means for removing electrolysis products, the anode units comprising a pair of spaced foraminous electrical current anode distributors forming a space for anolyte therebetween, means for flowing aqueous halide solution through the said anolyte space and means for removing electrolysis products therefrom and means for uniformly compressing the units and membranes together whereby the current distributors are in firm electrical contact with their respective electrodes and to a novel method of generatin

Abstract: A cell is provided having an anode and cathode separated by an ion permeable membrane or diaphragm wherein an electrode layer is bonded to or otherwise embedded in on at least one and usually to both sides of the membrane. Polarity is imparted to a bonded or embedded electrode by pressing a crinkled resiliently compressible fabric against the membrane carrying the electrode layer. This fabric is substantially coextensive with the electrode layer and is constructed so that when compressed it exerts a substantially uniform elastic reaction pressure against the membrane carrying the electrode layer or a pliable foraminous sheet, i.e. screen, interposed between the membrane carrying the electrode layer and the resiliently compressible fabric. The resiliently compressible fabric has the ability of also transmitting pressure laterally so that pressure applied may distribute across the entire area of the layer and tendency to have local areas of too low or too high pressure is minimized or reduced.

Abstract: Cationic membranes permeable to ions but fluid impermeable comprising a partly sulfonated terpolymer of styrene, divinylbenzene and at least one member of the group consisting of 2-vinylpyridine, 4-vinylpyridine and acrylic acid, the degree of sulfonation varying through the membrane cross-section from a maximum or the anodic surface to a minimum at the cathodic surface, their preparation, their use in electrolysis cells and electrochemical processes.

Abstract: Cationic membranes permeable to ions but fluid impermeable comprising a partly sufonated terpolymer of styrene, divinylbenzene and at least one member of the group consisting of 2-vinylpyridine, 4-vinylpyridine and acrylic acid, the degree of sulfonation varying through the membrane cross-section from a maximum at the anodic surface to a minimum at the cathodic surface, their preparation, their use in electrolysis cells and electrochemical processes.

Abstract: Porous and electrolyte permeable composite diaphragms for electrolysis cells comprising a chemically inert, fibrous porous matrix or substrate impregnated with a copolymer of divinylbenzene and at least one member of the group consisting of 2-vinylpyridine and 4-vinylpyridine, method of electrolysis of an electrolyte using the said diaphragms and an electrolysis cell containing said diaphragms.

Abstract: Novel membranes for electrochemical cells permeable to anions, fluid impervious and resistant to halogens and acidic and oxidizing environments comprised of copolymers of (1) divinylbenzene or halogenated vinyl monomers and (2) at least one member of the group consisting of 2-vinylpyridine and 4-vinylpyridine with the copolymers being optionally N-alkylated or N-arylated, processes for preparing the said membranes and electrochemical cells and processes using the said membranes.

Abstract: Porous and electrolyte permeable composite diaphragms for electrolysis cells comprising a chemically inert, fibrous porous matrix or substrate impregnated with a copolymer of divinylbenzene and at least one member of the group consisting of 2-vinylpyridine and 4-vinylpyridine, method of electrolysis of an electrolyte using the said diaphragms and an electrolysis cell containing said diaphragms.