Abstract: The invention relates to a method of continuously removing and obtaining ethylene diamine tetracetic acid (EDTA) from the process water of electroless copper plating. For that purpose the process water containing the EDTA is directed into an electrodialysis cell alternatingly equipped with bipolar membranes and anion exchange membranes and/or cation exchange membranes, and to which a potential difference is applied. The EDTA is converted into its charge-neutral form by means of protonation, and the protons required for that purpose are generated via bipolar membranes through electrodialysis. The required pH-value is adjusted by a pH-controlled electric field regulation via the bipolar membranes.

Abstract: An electrode is arranged in an integrally formed, seamless, self-supporting tubular ion exchanger, and a liquid supply and discharge mechanism for circulating an electrolyte is arranged in the tubular ion exchanger to construct an electrode apparatus for the dialysis. When this apparatus is used for the dialysis of an electrodeposition coating solution, leakage of the coating solution into the electrode portion and leakage of the electrolyte into a tank are prevented.

Abstract: An improved process for purifying a nickel plating bath including a pyridine composition as an additive and which bath contains a breakdown product of the pyridine composition. The process has the following steps:a. adjusting the pH of the nickel plating bath to a pH of equal to or greater than 5.0;b. adding an effective amount of an oxidizing agent; andc. removing the breakdown product from the nickel plating bath.

Abstract: This invention provides a means of controlling the composition of electrodepositable photoresists emulsion. The system removes contaminants from the bath which may adversely effect the quality of the deposited coatings and allows for continuous monitoring of the conductivity of the system.

Abstract: A stamper cleaning apparatus comprises an electrocleaning tank for performing electrodegreasing, a washing room adjacent to this cleaning tank, a shower, disposed in the upper section of the washing room, for water-washing a stamper by spraying washing water onto the stamper while the stamper is positioned inside the washing room and is wet with an electrocleaning solution, a water drain tank, disposed in the lower section of the washing room, for collecting water after the stamper is washed with water and for draining the water, and a small drying room disposed in the upper section of the washing room for operating to heat and dry the stamper after the shower has operated during the predetermined time the stamper is held in the washing room.

Abstract: Heavy metals are reclaimed from a concentrated wastewater solution containing heavy metal cations and an acid by adding to the wastewater a bed of scrap aluminum in a total amount between about 160% and about 180% of the stoichiometric requirement for complete reduction of the dissolved heavy metal cations to their elemental states and adjusting the acid content of the wastewater to 5% to 20% by volume and allowing the heavy metal cations to react with the scrap aluminum to oxidize the aluminum and to reduce the heavy metal cations to their elemental states thereby producing demetallized wastewater which is neutralized with caustic to produce a treated effluent.

Abstract: Cyanide present in aqueous streams, such as effluents from electroplating and gold mining operations is reduced or elliminated by contacting the cyanide-containing stream with oxygen and carbon dioxide in the presence of cupric ions. The oxygen may be provided by air or oxygen and the contacting is carried out at until the pH of the aqueous stream is reduced to a value in the range of about 6 to 8 and preferably 6.5 to 7.5. Cupric sulfate has been found to be particularly effective for the described reaction.

Abstract: A process for recovering copper from cupric ion containing aqueous solutions which comprises adding to the aqueous solution containing cupric ions an amount of reducing agent which corresponds from 0.1 to 10 moles of reducing agent per mole cupric ion, and heating the reaction mixture in the absence of oxygen in a closed vessel to a temperature of from 170.degree. to 240.degree. C., said reducing agent being one or more members of the group consisting of:(a) organic aldehydes RCHO (R=H, C.sub.1 to C.sub.5 alkyl)(b) carboxylic acids R COOH (R=H, linear or branched C.sub.1 to C.sub.5 alkyl)(c) hydroxycarboxylic acids R.sub.1 COOH (R.sub.1 =HO(CH.sub.2).sub.n, CH.sub.3 CH(OH)--, CH.sub.3 (CH.sub.2).sub.n, CH(OH)-- with n=1 to 3)(d) dicarboxylic acids R.sub.2 COOH (R.sub.2 =HOOC(CH.sub.2).sub.n with n=1 to 3)(e) amino acids R.sub.3 COOH (R.sub.3 =CH.sub.3 (CH.sub.m CH(NH.sub.2)-- (CH.sub.3).sub.2 (CH).sub.m CH(NH.sub.2 -- with m=1 to 3, CH.sub.3.CH(OH)(NH.sub.2), HOO C.CH(NH.sub.2).(CH.sub.2).sub.

Abstract: An apparatus for preparing and cleaning a machining liquid of an electroerosion machine comprises a filter, to which a concentrate flow is supplied from a concentrate tank and from which a permeate flow is drained off. Over a considerably extended time the quality of the machining liquid is maintained within a desired quality range, because the filter is constructed as a membrane filter and a disposal container having a fleece filter is provided to which is supplied at least part of the concentrate flow from the membrane filter and from which the partial flow filtered through the fleece filter is returned to the concentrate tank.

Abstract: There is disclosed a method for recovering silver from photographic processing solution by electrolysis, in which method the cathode potential is set at a potential range wherein a precipitate of silver sulfide is formed in the electrolytic cell. According to the method, intensive silver recovering leading to low concentration of residual silver in the solution is achieved. Structure of electrolytic apparatus enabling easy separation of silver sulfide precipitates is also disclosed. Application of lead peroxide to the material of anode improves the life of the anode. Further advantages of the method are remarkable decreases in COD and iron contents of waste solution.

Abstract: A system for removing cyanide and related species from a cyanide-containing waste fluid, for example, of the sort generated by mining operations, includes means for generating hydrogen peroxide by the burning of a fuel and the quenching of that burning with the waste fluid. At least a portion of the cyanide content of the waste fluid is eliminated by oxidation with the hydrogen peroxide, and the quenching can also provide organic material to serve as a carbon source for microbes which degrade residuel cyanide in the treated waste stream.

Abstract: A method for waste treating metal containing solutions comprising decomposing the metal from the solution in the substantial absence of air and separating the decomposed (precipitated) metal from the solution.

Abstract: This invention relates primarily to a waste water treatment and recycling system for an electroplating line. Electroplating lines typically produce waste products which may be defined as environmentally hazardous. The present invention provides for a system of complete recycling of such wastes from an electroplating line which includes (I) a plurality of treatment stations, where each station consists of a treatment tank and a rinse tank, and (II) means for sequentially moving metallic parts for treatment therein from a treatment tank and a rinse tank of a first treatment station, to a treatment tank and rinse tank of a second treatment station.

Abstract: Removal of dissolved copper from solution according to the present invention involves treatment of waste solutions such as electroless copper overflow solutions with aluminum particles under reaction conditions promoting precipitation of dissolved copper from solution as metallic copper. Copper plating solutions having high concentrations of dissolved copper are inactivated in overflow reservoir (12) by addition of an inactivating agent from reservoir (14) to prevent plating of metallic copper onto vessels and conduits during collection, storage and/or transport of the solution. Inactivation of the copper plating solution is followed by precipitation of dissolved copper from solution as metallic copper in reaction vessel (20) by addition of aluminum particles from reservoir (24).

Abstract: This invention relates to a method of forming a plating layer on ceramic chip surfaces by electroless plating, and to electronic parts manufactured by this method. Such electronic parts include a metal film fixed resistor, a capacitor, a resistor for sensing purposes and a patterned substrate, for example. Ceramic chips are immersed in a plating solution containing chromium chloride, nickel sulfide, sodium hypophosphite, a chelating agent and thiourea. Then each ceramic chip is coated with a plating layer by electroless nickel plating while adjusting pH value of the plating solution with a pH regulating liquid. The resulting electronic parts have an initial resistance of 0.02 to 100 ohm or more and a temperature coefficient of resistance of a two-digit figure or less in ppm.

Abstract: There is disclosed a treatment of exhaust gases containing detectable quantities of multivalent heavy metals in high oxidation states by introducing a sulfur reductant into contact with the exhaust gases and maintaining the contact of the sulfur reductant with the exhaust gases under appropriate conditions to favor the reduction of the heavy metal to an harmless, lower oxidation state. Sulfur dioxide is preferred for this treatment. After the treatment with the sulfur reductant, the exhaust gases are treated to remove the excess or residual amounts of the sulfur reductant and the compounds of higher oxidiation states of the sulfur which have been formed by the reduction of the heavy metal. When sulfur dioxide is used, the exhaust gases can be passed into contact with an aqueous alkaline solution which absorbs oxides of sulfur, such as sulfur dioxide and trioxide from the exhaust gases.

Abstract: A process and an apparatus for recovering a precious metal compound, in which the precious metal compound is separated from impurity metals by use of a reverse osmotic membrane, and the separated precious metal compound is recovered in a concentrated state through electrodialysis employing anion-exchange and cation-exchange membranes, whereby the precious metal compound in a process liquid can be recovered efficiently. When the recovered precious metal compound is added in the as-is form to precious metal plating solution, it is possible to control the plating solution.

Abstract: A process for the common or simultaneous separation of arsenic, antimony, bismuth and iron from electrolyte solutions of valuable metals by solvent extraction and subsequent recovery of the contaminating elements, which process is characterized in that aqueous mineral-acidic electrolyte solutions of valuable metals are admixed with a sparingly water soluble organic solvent containing at least one hydroxamic acid, the aqueous and organic phases are thoroughly mixed, the contaminating elements arsenic, antimony and bismuth are precipitated from the organic phase by direct sulfide precipitation, the sulfides are separated, and the extracted iron is subsequently reextracted with a water soluble iron-complexing agent into an aqueous phase and recovered.

Abstract: A forced air, ambient temperature, evaporator coupled to an electroless copper plating bath and to a purification system for replenishing and maintaining the stability of the plating bath, which bath tends to become depleted as the result of the reduction of water soluble cupric salt in an alkaline solution under copper plating and reducing conditions and in which the rate of evaporation of water from the surface thereof is insufficient to preclude growth in the volume thereof resulting from liquid additions thereto required to replace consumed constituents, thus giving rise to a need for bailout to prevent overflow thereof, solves the following problems: evaporation is independent of plating bath geometry; very high evaporation rates enable bailout to be zero at all plating loadings and plating thicknesses; the high evaporation rates provide sufficient cooling whereby the electroless copper solution can be introduced directly to the purification system with no additional cooling; dragout losses may be comple

Abstract: A process for removing dichromates from chlorate-rich solutions containing hypochlorite and dichromate ions and produced by the electrolysis of brine. The dichromate is reduced in a two-stage process by the addition of ammonia under controlled conditions of pH and temperature to a mixed di- and trivalent chromium hydroxide which is precipitated from solution and removed. The process provides an economical method of recovering chromium from electrolytically produced chlorate solutions.

Abstract: A process for removing nickel and phosphorus species from a spent electroless nickel plating solution is described. This process involves an initial precipitation of phosphite values from the plating solution, followed by oxidation of hypophosphite and remaining phosphite to phosphate values, and the final removal of phosphate and nickel by lime precipitation. The treated plating solution is then separated from the precipitants, such as by filtration, and preferbly contain less than 1 milligrams/liter of nickel and/or total phosphorus species. This process is a cost effective method for treating spent electroless nickel plating solutions which is readily adaptable for on-site use.

Abstract: To provide for essentially uniform current density at the respective cathodes of an electrolytic cell, a plurality of cathodes are located, spaced from each other, at one side of an anode, and resistance elements connect the respective cathodes to a negative supply terminal or supply bus (N, 11), the resistance elements having respective resistance values which decrease as the distance of the respective cathode from the anode increases. A single anode (2), preferably separated from the cathode space (5) by an ion exchange membrane (6), can be located centrally within the cathodes; or two anodes can be located spaced from each other with a plurality of cathodes located therebetween. Each cathode is connected with a quick disconnect plug-or-push terminal to the respective current supply, which may be a controlled constant current source.

Abstract: The continuous flow of fresh water to and metal hydroxide contaminated water from a counter flow rinse tank in an electroplating apparatus is greatly reduced or eliminated by a parallel flow path provided to an adjacent ion exchange treatment unit and from the ion exchange unit back to the rinse tank. The rinse tank is fitted with a submerged pump to provide the rinse water to the ion exchange unit and through this unit back to the rinse tank.

Abstract: An electroplating system with improved water use efficiency and unique waste water treatment which enables operation without access to public sewers thereby permitting compliance with governmental regulations regarding disposal of waste water. Water use efficiency is achieved by means of limited use of overhead water sprays, multiple rinse tank backflow to the prior process tank and water evaporation from said process tanks. In addition, all waste water not returned to the prior process tank locally at each plating subassembly is transferred to an inplant sump for common evaporative treatment.

Abstract: An electroless copper plating bath is improved so as to facilitate its regeneration in an electrodialysis cell. The bath includes elevated amounts of an added salt, preferably as Na salt. The elevated sodium ion level serves as additional counter-cation to hydroxyl ion which is produced at the cathode of the electrodialysis cell. The excess anion from the added salt increases the rate of out-migration of by-products, such as formate ions and sulfate ions, relative to hydroxyl ions through an anion permselective membrane.

Abstract: The zero discharge spray system comprises a tank for collecting and storing inse water, a set of spray nozzles aligned within the tank, and a pump for both pumping used rinse water through the spray nozzles and/or to the plating bath as makeup for evaporation. A timer level control system maintains the plating bath level and the rinse tank level, and limits the nozzles spray time. The system also includes a fresh water spray for final rinse of plated parts. By using a controlled spray rinse system which reduces the amount of water added to the system so as not to exceed that lost by evaporation, no contaminated rinse water is discharged as waste.

Abstract: We have discovered an improved, energy efficient method for recovering and regenerating acid from a solution comprising acid and salt.

Abstract: A process for separating arsenic from acid aqueous solutions containing arsenic and other metal ions. The process involves bringing the acid aqueous solution into contact with a water-immiscible organic diluent consisting of hydrocarbons, alcohols or their mixtures, in which there is dissolved as solvent at least one polyol. The solvent thereby extracts the arsenic, which is then re-extracted with a counter-solvent.

Abstract: A process is described for the substantially complete recovery of cyanide reagent and metal forming water soluble metal-cyanide complexes contained in mill effluents and waste waters. The process is comprised of a loading cycle wherein the metal-cyanide complexes are adsorbed onto a basic ion exchange resin and the free cyanide containing column effluent is returned to the mill. The metal ions, which are usually mostly copper, nickel and zinc, and the complexing cyanide are eluted in the subsequent regenerant cycle by an acid solution having controlled pH and controlled redox potential, the latter being measured against the saturated calomel electrode. The preferred oxidant to control the redox potential of the regenerant solution is hydrogen peroxide. The generated hydrogen cyanide is sparged with air, or removed by subatmospheric pressure from the regenerant solution, and dissolved in an alkaline scrubber solution for reuse. The metal ions are recovered from a bleed solution.

Abstract: A process and apparatus for regulating an electrodialyzer having a stack of ion-exchange membranes (2, 3) immersed in an electric field, and including sampling the dilute solution at the discharge (6), measuring in a cell (12) the content of a predetermined ion substance of this sample, in particular the content of free cyanide, and driving by means of a processing unit (14) a pump (15) as a function of that content so as to add a solution containing the ion substances (free cyanides) in an amount inversely related to the measured content at the intake (5) of the electrodialyzer, thereby eliminating electrodialyzer shutdown and membrane clogging.

Abstract: A method is disclosed for the selective removal of metal ions from plating solutions comprising contacting the plating solutions with liquid organic complexing agents such as oximes or phosphoric acid esters or microporous material, preferably anisotropic, the microporous material being impregnated with such substances. The microporous material may be in various forms, including beads, fibers, sheets and gels. Copper, zinc and iron contaminants are effectively removed from nickel-plating solutions.

Abstract: A process for the selective extraction of arsenic from acid solutions containing other metals comprising treating the solutions with polyhydroxybenzene derivatives in organic diluent; mono- and di- alkyl derivatives containing at least four alkyl carbon atoms of pyrocatechol and pyrogallic acid are particularly contemplated for use in the removal of arsenic from strongly acid copper-containing electrolyte solutions.

Abstract: A method is disclosed for the elimination of hazardous metal wastewater and sludges by recovering the non-ferrous metals zinc, nickel, copper (II), cadmium or chromium (III) present in an aqueous sludge comprising mixed metal hydroxides by selectively precipitating the ferrous metal ions present while maintaining the non-ferrous metal ions in solution, isolating the precipitate and then precipitating the non-ferrous metal ions from solution.

Abstract: A method of and apparatus having utility in an electrodialysis and electrosynthesis process energized by direct eletrical current for the purification and replenishment of an electroless copper plating solution comprises indirectly measuring the hydroxide production that is put into and left in the electroless copper plating solution from a catholyte solution in which the hydroxide is synthesized by measuring the net hydronium ion content of an anolyte solution into which waste products from the electroless copper plating solution are transported, and adjusting the flow of direct electrical current in response to the net hydronium ion production in the anolyte solution.

Abstract: An electroplating system with improved water use efficiency and unique waste water treatment which enables operation without access to public sewers thereby permitting compliance with governmental regulations regarding disposal of waste water. Water use efficiency is achieved by means of limited use of overhead water sprays, multiple rinse tank backflow to the prior process tank and water evaporation from said process tanks. In addition, all waste water not returned to the prior process tank locally at each plating subassembly is transferred to an inplant sump for common evaporative treatment.

Abstract: A multicompartmented cell suitable for use as electrochemical and chemical reactor cells is formed with a freely-extendible tubular membrane which is a thin-walled, preferably ion selective permeable, membrane sleeve which from a dry condition tends to expand and lengthen upon hydration. An end plug fastened at one end of the membrane provides fluids closure whereby the closed membrane end with its end closure is free to move, i.e., is unattached. A cell head to which the other end of the membrane is connected, together with the membrane and the end plug define a compartment. The cell head is provided with means for ingress and egress of fluids to and from such compartment and can also be provided with electrical access to an appropriate electrode. External to the membrane sleeve is a suitable containing means spaced from the membrane to form a compartment outside the membrane, the containing means being sufficient in size to accommodate the membrane in expanded and lengthened condition.

Abstract: A flushing fluid recycling system used with an electroerosion machine which includes a regenerating unit, i.e. an ion-exchange column as deionizer, through which the used liquid medium, e.g. water, collected from an electroerosion zone is passed for regeneration and return to the electroerosion zone. A pump is periodically actuated to intermittently pass the liquid medium through the deionizing column with predetermined on-time and off-time regardless of whether the value of an electrical property, e.g. specific resistance of the fluid, determined by a sensing unit lies above a certain level. However, the ratio of the on-time to the off-time is altered depending on the particular value of the electrical property sensed.

Abstract: A membrane-based solvent extraction system is used to separate zinc from plating wastes and to recycle the concentrated zinc solution to the plating bath. Di-2 ethylhexylphosphoric acid (DEHPA) is used as an organic carrier, and an acid or salt solution is used as a stripping agent in this process.

Abstract: An evacuator system employed in an evaporative waste recovery system uses an eductor to create a partial vacuum. The partial vacuum is selectively employed to evacuate concentrate and distillate from an evaporator unit for transferal to respective concentrate and distillate containers. A plurality of air operated valves are automatically operated to transfer concentrate and distillate for reuse in a plating process system.

Abstract: A mechanical structure for a three-compartment electrodialytic cell unit utilizing spaced anion permselective membranes is characterized by the ease of assembly and disassembly of the parts thereof and adaptation for use as a standard structural component for repeated use in the construction of multiple cell electrodialysis apparatus, with the internal flow of the catholyte and anolyte and an electroless copper solution to be chemically treated being controlled and organized by a plurality of ports in the assembled parts, and with electrical energization of the individual cell units in a multi-cell structure in series, in parallel or series-parallel.

Abstract: An electroplating solution recovery system is disclosed which includes an electroplating tank containing an electroplating solution and one or more rinse tanks containing rinse solutions. A tubular interconnection extends between a first of the rinse tanks and the electroplating tank and is operative for transferring rinse solution from the first rinse tank to the electroplating tank by a siphoning process when the level in the plating tank is significantly lower than the level in the rinse tank. Additional tubular interconnections extend between the other rinse tanks for interconnecting them in series relation so that the solution in the tanks is automatically replenished as it is consumed, the solution level in the last tank in the series, however, being replenished from a continuous water supply. Maximum recovery of plating solution is assured by the system, and the pollution levels in the overflow effluent from the last rinse tank are minimized.

Abstract: A ventilating system for a high speed electroplating apparatus having a pretreating section, a plating section and a post treating section for electroplating a workpiece sequentially transferred from each section by a conveyor. Each section has a cover which together completely enclose the apparatus except for inlet and outlet areas. An exhaust fan is positioned in a duct connected to the enclosed treating sections for exhausting the accumulated gases to the atmosphere outside the work area.

Abstract: A method for purification of a sulfuric acid solution such as, for example, a copper electrolyte which entrains at least one metal ion species selected from the group consisting of antimony ions, bismuth ions, and iron ions and having a sulfuric acid concentration of at least 50 g/liter is disclosed. The method comprises exposing the sulfuric acid solution to a chelating resin possessing aminomethylenephosphonic acid group as a chelate forming group thereby effecting adsorptive separation of the aforementioned at least one metal ion species from the solution. By the method described above, the antimony ions, bismuth ions, and/or iron ions contained as impurities in the copper electrolyte can be easily and efficiently separated out of the system without entailing any ecological problem.

Abstract: A process and electrodialytic cell for electrodialytically regenerating an aqueous, spent electroless copper plating bath which contains alkali metal salts as reaction products of the electroless plating process. In the process, the spent copper plating bath is introduced into a regeneration compartment of an electrodialytic cell. Anions of the alkali metal salts in the spent copper plating bath are electrodialytically transferred through an anionic membrane into an acid formation compartment. Hydroxyl ions are electrodialytically transferred through the anionic portion of a bipolar membrane to a regeneration compartment to regenerate the bath. The electrodialytic cell of the invention has means for establishing and maintaining in a plurality of regeneration compartments the spent electroless copper plating bath.

Abstract: The invention relates to the protection of the environment.The invention may be most efficiently used for removing from aqueous media ions of heavy, non-ferrous and noble metals, organic substances, flotation reagents and petroleum products.The process comprises dissolving a metal anode in the presence of a non-soluble cathode and precipitating organic and inorganic impurities on the resultant compounds. The precipitation is conducted using a cathode made of a material having a potential which is higher than the potential of the anode, the electrodes being alternately brought in contact with the air oxygen and the liquor being treated.An apparatus for carrying out the process comprises a drum having openings for charging a metal scrap and the liquor being treated and for discharging the resultant precipitate. Wings are concentrically arranged on the inner surface of the drum. A perforated partition wall is provided adjacent to the outlet opening for preventing the loss of scrap from the drum.

Abstract: A reticulate cathode, for use in an electrolytic cell for scavenging a metal from a solution containing ions of the metal, comprising an open cell electrically conductive foam which has been coated with conductive carbon particles. A cathode assembly comprises an electrically conductive support member to which the conductive foam is secured, the support also serving as the current conductor. The resistivity of the foam is less than 3000 ohm-cm, preferably in the range from about 40-1000 ohm-cm, and it has a pore size in the range from about 10 pores per inch (ppi) to about 100 ppi, and a void fraction in the range from about 0.5 to about 0.98. In its most preferred embodiment, the cathode is preplated with copper in an amount from about 0.5-20 g/ft.sup.2 of active area, sufficient to impart rigidity to the cathde and avoid using a support member.

Abstract: The disclosure relates to a process and apparatus for the treatment of sodium-nitrate-containing electrolytes during the electrochemical machining of the surfaces of iron-containing workpieces. By adding an oxidizing agent, more particularly ozone, increased production of nitrite in the electrolyte is prevented and, thereby, premature passivation of the surface of the workpiece during the electrochemical metal removal. An apparatus for the oxidation of the electrolyte is comprised of a processing station inserted into the electrolyte circuit, an ozone generator, and a reactor.

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 an ion selected from the group consisting of scandium, yttrium, lanthanum, titanium, zirconium, hafnium, molybdenum, arsenic, selenium, tellurium, cerium, uranium, and tin 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: 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 a metal ion selected from the group consisting of Gold, Silver, Platinum, Palladium, Rhodium, Iridium, Osmium, Ruthenium, Rhenium, Gallium, Germanium, Indium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, and Praseodymium 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: The invention comprises improvements in inert anode electroplating processes that make possible the utilization of typically inexpensive and otherwise advantageous cation-yielding compounds for replenishing the plating bath, compounds that typically are not well suited for such use in prior art systems due to their relatively low dissolution rate which typically requires their use in powder form, and the tendency of the powder particles to aggregate. Exemplary applications for the improved plating process are in Cu-, Ni-, and Pd-plating, and exemplary cation-yielding compounds or CuO, NiO, PdO, Cu(OH).sub.2,Ni(OH).sub.2, and Pd(OH).sub.2. The improvements according to the invention comprise agitating the powder/electrolyte mixture or slurry in a reactor vessel separate from the plating tank, and maintaining the cation concentration in the plating tank within predetermined limits. Agitation typically requires power input to the slurry of at least about 2.