Abstract: A process for electrodepositing chromium on a conductive substrate employing an electrolyte containing trivalent chromium ions, a complexing agent, and hydrogen ions to provide an acidic pH in which a conductive substrate to be electroplated is immersed in the electrolyte and is cathodically charged and current is passed between the substrate and an anode at least a portion of the surfaces of which is comprised of ferrite whereby the formation of detrimental hexavalent chromium ions in the electrolyte is inhibited and the stability of the pH of the electrolyte is improved.

Abstract: Use of succinosuccinic acid diesters of the formula ##STR1## in which R is an alkyl, alkenyl or cycloalkyl having 4 to 24 C atoms, either dissolved in a water-immiscible organic solvent, or at elevated temperature in the form of their melts, as cation-selective liquid membranes.

Abstract: Wastewater from metal plating operations is treated to remove heavy metal and other contaminants, including toxic organic materials, chelating agents, and cyanide. The wastewater is passed through the cathode and anode of an electrochemical reactor in which the cathode preferably comprises a felt mass of conductive fibers and the anode comprises porous carbon, carbon fibers or metal oxides. A method and apparatus are disclosed which are particularly useful in removing impurities from plating plant wastewater.

Abstract: The invention relates to a process and a solvent for extraction of the chromates present in an aqueous solution. According to the invention, the aqueous phase is brought into contact with an organic phase comprising 2 to 10% by volume of a solvent selected from the group of tertiary or quaternary amines and 15 to 40% of a solvent selected from the group of esters of phosphoric acid in a diluent based on petroleum hydrocarbons. The invention is applicable to the production of concentrated solutions of chromates easily recyclable from an extraction of the chromates contained in an industrial solution.

Abstract: In a preferred embodiment, plating chemicals are recovered from contaminated rinse water using an electrodialysis recovery unit immersed directly in an electroplating bath between a cathode intended to be plated and an anode. Electrodialysis is driven parasitically by the electroplating currents, thereby eliminating the cost of additional equipment dedicated solely for electrodialysis. The unit is sized and positioned so that only a relatively minor portion of the total plating current is employed for electrodialysis, thereby permitting a sufficiently high current density at the cathode to electrodeposit a dense, commercially acceptable metal plate.

Abstract: The antimony in an antimony-containing copper electrolyte is removed by contacting the antimony-containing copper electrolyte with activated carbon at between room temperature and 60.degree. C.

Abstract: An aqueous acidic trivalent chromium electrolyte and process for electrodepositing chromium platings comprising an electrolyte containing trivalent chromium ions, a complexing agent, halide ions, ammonium ions and a reducing agent comprising neodymium ions present in an amount effective to maintain the concentration of hexavalent chromium ions formed in the bath at a level at which satisfactory chromium electrodeposits are obtained.

Abstract: Gold and/or silver is leached from comminuted ore with an alkaline cyanide lixiviant at a superatmospheric pressure of at least 25 bar and with high purity oxygen (at least 90% pure) to reduce the residence time at high yield.

Abstract: This disclosure is directed to a membrane or diaphragm-free, electrolytic process for removal of a significant portion of at least one metal contaminant from waste water containing it comprising contacting said waste water with a plurality of anodes, each anode having openings to permit the flow of waste water therethrough, and a plurality of metallized organic polymer foam reticulate cathodes wherein said anodes and reticulate cathodes are arranged in alternating manner and electrically energized.

Abstract: An improved aqueous acidic trivalent chromium electrolyte and process for increasing the tolerance of such electrolytes to the presence of deleterious contaminating metal ions which normally progressively increase during commercial operation of the electrolyte ultimately resulting in chromium electrodeposits which are commercially unsatisfactory due to the presence of streaks, clouds and hazes in the deposit. The improved composition contains controlled effective amounts of thiazole and benzothiazole compounds which are effective to mask the adverse effects of such contaminating metal impurities and which also enhance the codeposition of such metal contaminants on the parts being plated thereby reducing, and in some instances preventing the progressive accumulation of such contaminating metal ions in the electrolyte.

Abstract: Process for reclaiming stannous ion by reducing the same in an electrolyte to stannic ion through a simple operation in a short period of time, which comprises the steps of preparing the electrolyte in an acidic range as required and then adding metallic tin to the electrolyte and heating the mixture to at least 80.degree. C., in order to reduce the stannous ion oxidized in the electrolyte containing tin salt to obtain a stable electrolyte treated product. This process may be utilized particularly for effectively reducing and reclaiming an electrolyte which contains tin salt used for electrolytically coloring aluminum.

Abstract: A process for regenerating electroless plating bath comprising the steps of:(i) continuously or intermittently taking out a part or the whole of chelating agent-containing copper electroless plating bath from an electroless plating tank, followed by removing off the copper ion content from said bath;(ii) acidifying the thus obtained solution for precipitating the chelating agent therefrom and recovering the precipitated chelating agent;(iii) supplying said recovered chelating agent to an anodic cell separated by an exchange membrane from a cathodic cell having cathode, said anodic cell having copper anode, wherein in case a neutral or alkaline electrolyte solution is supplied to said cathodic cell said partitioning membrane is an anion exchange membrane or cation exchange membrane, while in case an acidic electrolyte solution is supplied to said cathodic cell said partitioning membrane is a cation exchange membrane, and applying direct current between both electrode; and(iv) then, recycling the solution withi

Abstract: A process is provided for the waste treatment of metal plating solutions. One embodiment of the process comprises removal of the metal values contained in solution and inactivation or destruction of the complexing agent's ability to complex heavy metals. A second embodiment comprises inactivation or destruction of the complexing agent as a first step, formation of a sludge if not formed by inactivation of the complexing agent and sludge removal. Either embodiment permits direct discharge of spent plating solutions into the environment without violation of federal or municipal regulation.

Abstract: An electronic water treating device comprising a brass body from which projects a graphite anode and to which is secured a stainless steel canister which functions as a cathode. The device includes an electronic power head connected to an external power supply. A 115 volt AC house current is transformed into two 6.3 volt circuits. The first anode powered circuit receives 6.3 volts which is rectified through a diode bridge and powers the anode through a biased resistance. The second 6.3 volt circuit is rectified through a diode and passes through a condenser and resistance through a transistor and resister to the anode. This latter circuit is a voltage measuring circuit interconnected through a relay to a warning light which is energized and lighted if substantial variation in the current being transmitted occurs. This usually arises when an accumulation of sludge-like calcium carbonate, calcium sulphate and magnesium collects in the canister.

Abstract: An electroplating process is disclosed for coating metal strip or sheet with a nickel-zinc alloy comprising at least 80% nickel. Steel sheet coated with the alloy exhibits excellent weldability.

Abstract: A method for removing copper contaminants from acid electroplating baths comprising adding to the bath sodium formaldehyde sulfoxylate. The presence of the sodium formaldehyde sulfoxylate overcomes overall plating haze and low current density dullness due to copper contamination in the acid tin bath.

Abstract: Use of succinosuccinic acid diesters of the formula ##STR1## in which R is an alkyl, alkenyl or cycloalkyl having 4 to 24 C atoms, either dissolved in a water-immiscible organic solvent, or at elevated temperature in the form of their melts, as cation-selective liquid membranes.

Abstract: This invention is directed to a membrane or diaphragm-free electrolytic cell device for removal of a metal(s) present as a contaminant(s) in waste water comprising a nonconductive cell box having an upper peripheral flange, anode and cathode bus bars located on said cell box below said flange, inlet and outlet means to pass the liquid through the electrodes contained in said box, means to space the anodes and cathodes contained within said cell box, a plurality of anodes having openings to permit the flow of waste water therethrough, a plurality of reticulate cathodes, and means connecting the anodes and cathodes, respectively, to said bus bars and to a source of electrical energy whereby the metal contaminant(s) present in such water are deposited on the reticulate cathodes predominantly.

Abstract: This invention concerns the electrochemical removal of metal ions and certain other contaminating ions from aqueous solutions and moist gas streams. Direct current from an external source is caused to flow through electrically conductive particulate elements or packing forming a bed of low electrical conductivity from two or more oppositely charged spaced electrodes maintained in direct physical contact with conductive particulate elements or packing. The aqueous solution or moist gaseous stream to be treated is brought into contact with the conductive bed while current is supplied to the electrodes and flows through the bed. The characteristics of the system are such that each bed element exhibits bipolar properties causing a multiplicity of electrically positive and negative sites to exist within the bed at which electron transfer with the pollutant ions occurs, changing their state and effectively removing them from the fluid.

Abstract: An ion transfer membrane assembly, for electrochemical processes, is provided which includes a plurality of layers of capillary material and a structure for compressing the layers together to control the water permeability of the membrane. The membrane includes a plurality of layers of capillary material, each of the plurality of layers being formed from a corrosion-resistant relatively soft, film, such as a thermoplastic film, having surface manifestations formed on it, which manifestations define the capillaries. The surface manifestation may be formed by embossing, frosting, etching, etc. A plurality of layers of corrosion-resistant, springy, porous capillary material, such as a polyester non-woven web, may be interspersed with the capillary material film layers, and a plurality of layers of smooth-surfaced film may also be interspersed with the capillary material film layers.

Abstract: The invention is an improved apparatus for the removal of sodium carbonate from cyanide plating baths. The method involves the precipitation of sodium carbonate by the effect of cooling the cyanide plating bath liquid. A container is submerged in the solution with the container opening extending above the plating bath solution level. The container is filled with dry ice and water which produces a temperature of approximately zero degrees centigrade inside of the container. The solution adjacent to the exterior of the container is cooled so that excess sodium carbonate is precipitated as a crystalline deposit. After a desired interval, the container is removed with the encrustation of sodium carbonate for disposal.

Abstract: An apparatus and method for removing charged ions from solution by treating the solution with electrodialysis followed by Donnan dialysis. One of many applications is for treating the baths associated with the metal finishing, e.g. plating, anodizing, or etching, industry. For example, charged ions can be removed from the rinse baths of a plating line by treating the rinse water of a first rinse bath following the plating bath with an electrodialysis unit and returning the concentrated solution to the plating bath, and treating a second rinse bath following the first rinse bath with a Donnan dialysis unit to produce an additional concentrated solution and a diluted effluent which may be either discharged into a sewer or stream, or readily destroyed.

Abstract: A process for the removal of lead content in anode slime by subjecting the latter to primary and secondary leach in a medium of an ammonium acetate solution at a temperature not exceeding 80.degree. C. Whereby lead dissolution is maximized and other metals are minimized. Separate the leach solution from the undissolved slime residue, crystallize lead from the separated leach solution and recover the crystallized lead acetate.

Abstract: A process for recovery of reusable chromic acid from waste chromic acid solution containing impurities, which process comprises a first step in which the solution containing chromic acid is introduced into the cathode compartment in an electro-dialysis process and free chromic acid or chromate ions in the above solution are transferred to the anode compartment, a second step in which H.sub.2 SO.sub.4 is added in at least equivalent amounts to the heavy metallic ion contained in the outlet solution, in which chromic acid ion concentration is reduced, in order to convert chemical species of the contained metallic ion and increase the H.sup.+ ion concentration and then chromate ions in the resultant solution are extracted into an organic phase with contact of an organic solvent (A), and a third step in which residual amounts of chromic acid ion remaining in the aqueous raffinate from the second step are extracted into an organic phase with contact of an organic solvent (B).

Abstract: The gold content of a gold plating bath is replenished by circulating the plating solution through an AuCN containing vessel. The plating solution contains sufficient free cyanide to render the gold soluble by producing the soluble Au(CN).sub.2.sup.- ion.

Abstract: The use of aqueous inorganic carbonates or bicarbonates as the catholyte in the electrolytic purification of chromium plating solutions permits the cell to operate at a high capacity and a high efficiency without adversely affecting the oxidation state of the chromium ions in the solution.

Abstract: During recyclic use of a chemical copper plating solution, counter anions to copper ions, anions formed by oxidation of a reducing agent, and carbon dioxide by absorption of carbon dioxide from air, which all have an inhibiting effect upon the plating, and also sodium ions having no inhibiting effect are accumulated in the plating solution.These accumulated ions can be removed by electrodialysis. Particularly, regeneration can be satisfactorily regenerated by adjusting the pH of used chemical plating solution to 2-11 before the electrodialysis, and using a selectively monovalent anion permeable membrane as an anion exchange membrane at the electrodialysis.

Abstract: A stream containing chromium and other heavy metals is fed through an electrolytic cell having a flow-through anode of lead shot and a flow-through cathode. The stream passes through the lead shot, resulting in the formation of lead chromate at the anode that falls to a trap in the bottom of the cell. Heavy metals such as copper are plated out on the material forming the flow-through cathode.

Abstract: Anions such as chromate ions are removed from a stream of waste water through an anion selective membrane and are subsequently combined with hydrogen ions transferred across a cation selective membrane in a two-phase Donnan dialysis acid recovery process. In a preferred embodiment chromate ions recovered from an electroplating process rinse solution are recycled to an associated electroplating bath as chromic acid while the chromate ion-depleted rinse solution is recycled to an associated rinse tank.

Abstract: The invention concerns a method of treating liquids by means of oligodynamy, particularly of sullage waters. The waters are passed between metal electrodes supplied with electric current before being allowed to settle. The waters which have been subjected to the oligodynamic treatment are then submitted to at least one positive degassing operation and/or a part at least of the flocculate being formed is recovered and said flocculate is re-introduced into the water which has just flowed between the metallic electrodes. The flocculate resulting from the treated waters is then separated.

Abstract: The washings in a plating process is continuously circulated to an electrolytic cell in communication with the washing vessel. A metal contained in the washings is deposited on a cathode of the electrolytic cell.

Abstract: The present invention provides a novel process for forming a nickel foil having a controlled and predetermined hydrogen permeability. This process includes the steps of passing a nickel plating bath through a suitable cation exchange resin to provide a purified nickel plating bath free of copper and gold cations, immersing a nickel anode and a suitable cathode in the purified nickel plating bath containing a selected concentration of an organic sulfonic acid such as a napthalene-trisulfonic acid, electrodepositing a nickel layer having the thickness of a foil onto the cathode, and separating the nickel layer from the cathode to provide a nickel foil. The anode is a readily-corrodible nickel anode. The present invention also provides a novel nickel foil having a greater hydrogen permeability than palladium at room temperature.

Abstract: The invention is an improved apparatus for the removal of sodium carbonate from cyanide plating baths. The method involves the precipitation of sodium carbonate by the effect of cooling the cyanide plating bath liquid. A container is submerged in the solution with the container opening extending above the plating bath solution level. The container is filled with dry ice and water which produces a temperature of approximately zero degrees centigrade inside of the container. The solution adjacent to the exterior of the container is cooled so that excess sodium carbonate is precipitated as a crystalline deposit. After a desired interval, the container is removed with the encrustation of sodium carbonate for disposal.

Abstract: A process and installation for the integrated treatment of concentrated residual solutions resulting from the anodization of aluminium parts is described, in which caustic soda is employed in the pickling process and sulphuric acid in the anodization bath.The process comprises three sets of operations:(1) Production of aluminium sulphate in concentrated solution or in hydrated crystals, by the treatment of part of the residual solution from the anodization.(2) Production of precipitated aluminium hydroxide and a solution of sodium sulphate from residual anodization and pickling solutions.(3) Production of sodium aluminate from residual pickling solutions and aluminium hydroxide producted in (2). (FIG. 1.

Abstract: A process and electrodialysis cell for regenerating used chromic acid baths for reuse. The process and apparatus have an anolyte chamber and a catholyte chamber separated by a cation permeable membrane and utilize as an improved catholyte solution an aqueous mixture of a water soluble salt such as sodium sulfate. A preferred anode which is not decomposed by the chromic acid bath comprises by weight about 1.5% of silver, about 5% of antimony, about 3% of tin and the balance lead.

Abstract: A process for purifying copper sulfate solution by converting contained hexavalent selenium to tetravalent selenium which is amenable to removal from solution by heating and maintaining the solution at a temperature in the range of about 135.degree. to 220.degree. C. under a non-oxidizing atmosphere in the presence of bivalent iron. The converted selenium is removed from the solution either by co-precipitation with ferrous iron oxidized and hydrolyzed to ferric oxide at a temperature in the range of 135.degree. to 220.degree. C. and under an oxygen pressure of about 140 to 450 kPa or by cementation with a metal powder at a temperature in the range of about 25.degree. to 85.degree. C. at about ambient pressure under a non-oxidizing atmosphere.

Abstract: Method for regenerating an electrolytic liquid for tinning purposes in which the electrolytic liquid is freed from ions of foreign metals introduced into it during the tinning action, characterized by the steps of (a) detinning of the electrolytic liquid through electrolysis and (b) releasing of the foreign metal ions by means of a cation exchanger.

Abstract: A method and apparatus for treating aqueous rinse mixtures containing organic brightener additives having sulfur therein of nickel electroplating processes by adding acid to the rinse mixture, passing the rinse and acid mixture through a carbon filter to remove the brighteners and decrease the sulfur content of the mixture, and adding the filtered mixture to and reusing it in the semi-bright and bright nickel baths of the nickel electroplating process.

Abstract: In a method for phosphating the surface of a metallic substrate by treatment with a phosphating solution containing nitrite ions as the accelerator, an improvement wherein the supply of the nitrite ions to the phosphating solution is carried out by electrolytic reduction of nitrate ions present in the phosphating solution while changing the direction of the current flow at a fixed interval of time, whereby a desired concentration of nitrite ions in the phosphating solution is maintained without accumulation of alkali metal and/or ammonium ions unavailable for the phosphating and also without accumulation of precipitates on the electrode, and a uniform phosphate coating film having satisfactorily good coating properties is formed on said surface.

Abstract: A method for removing As, or As and Sb and/or Bi wherein acidic solution of sulfuric acid such as a copper electrolyte of having a free sulfuric acid concentration of less than 700g./l. and containing at least arsenic among arsenic, antimony and bismuth as impurities is warmed to be above 50.degree. C. or preferably above 60.degree. C. with the addition of H.sub.3 AsO.sub.4 in advance as required, one or a mixture of both of Sb.sub.2 O.sub.3 and Bi.sub.2 O.sub.3 preferably kneaded with water or the added solution is added to and mixed with the solution and the produced precipitate is separated to discharge the impurities out of the solution.

Abstract: Method for recovering metals from cyanide and hexavalent chromium plating baths comprising immersing plated articles in a reclaiming bath containing an aldehyde or an aldehyde percursor, and optionally an oxidizing agent, to precipitate the excess metal in the residual plating bath in the form of free metal or metal hydroxide and to decompose the cyanide and to reduce the hexavalent chromium to trivalent chromium. The plating bath and reclaiming bath are regenerated. Apparatus is provided to effect this process.

Abstract: A method for galvanic deposition of nickel from an electrolyte containing nickel sulfamate and nickel chloride is disclosed wherein the formation of intermediate products resulting from the oxidation of nickel sulfamate and the escape of anode sludge into the electrolyte are controlled to such an extent so as to reduce the amount of sulfur incorporated in the deposition to less than about 15 ppm.This results in avoidance of brittleness in the nickel deposition at high temperatures and allows the coated article to be welded. These properties were difficult or impossible to obtain in the prior art processes.

Abstract: Method for recovering metals from cyanide and hexavalent chromium plating baths comprising immersing plated articles in a reclaiming bath containing an aldehyde or an aldehyde percursor, and optionally an oxidizing agent, to precipitate the excess metal in the residual plating bath in the form of free metal or metal hydroxide and to decompose the cyanide and to reduce the hexavalent chromium to trivalent chromium. The plating bath and reclaiming bath are regenerated. Apparatus is provided to effect this process.

Abstract: Process for removing chlorine from an acidic zinc or cadmium sulphate solon, comprising adding thereto acid of Caro or an ammonium or alkali metal salt thereof.

Abstract: In a method for phosphating the surface of a metallic substrate by treament with a phosphating solution comprising nitrite ions as the accelerator, an improvement wherein the supply of the nitrite ions to the phosphating solution is carried out by electrolytic reduction of nitrate ions present in the phosphating solution, whereby a desired concentration of nitrite ions in the phosphating solution is maintained without accumulation of alkali metal and/or ammonium ions unavailable for the phosphating and a uniform phosphate coating film having satisfactorily good coating properties is formed on said surface.

Abstract: Process for removing impurities selected from the group consisting of manese, cobalt, nickel and thallium from an acidic zinc or cadmium solution comprising adding thereto acid of Caro or an ammonium or alkali metal salt thereof.

Abstract: A process for producing and operating an electroplating bath in which there appears NH.sub.4.sup.+ ions which impair the quality of the bath comprising adding salts of a hexanitrocobaltate-III complex to the bath to bring about precipitation of the NH.sub.4.sup.+ ions.