Abstract: A process for removing heavy metal ions or cyanide ions from a waste water stream originating in a metal plating plant or a mine comprising the steps of pretreatment in which the waste water stream is first pretreated by removing particulates, fats and oils; filtration by means of a first sand filter to remove suspended particulates down to 50 microns, a second bag filter to remove suspended particulates down to 3.5 microns, a third micro filter to remove particulates down to 0.

Abstract: The invention relates to a method and a device for regenerating exhausted tin-plating solutions which contain tin and copper ions, free complexing agent and complexing agent bound to the copper ions, as well as expended and unexpended reducing agent. By means of a suitable rinsing technique, the rinse water of the tin-plating process is concentrated to a 10 to 15 percent dilution of the process solution. The regenerating solution thus produced is fed to an electrolytic cell. The electrolytic cell comprises a cathode chamber, a middle chamber and an anode chamber. The cathode chamber is separated from the middle chamber by an anion-exchange membrane and the anode chamber is separated from the middle chamber by a cation-exchange membrane. The regenerating solution is initially provided in the cathode chamber. Here, the interfering copper component is cathodically deposited.

Abstract: The invention provides a process for preparing bismuth compounds, in particular a process for preparing highly concentrated solutions of bismuth methanesulfonate, that are stable to hydrolysis.The preparation takes place from aqueous solutions of bismuth compounds of the formula (I)BiX.sub.3 (I)by subjecting acid of the formula (II)HX (II)whereX is the anion of a mineral acid, an organic acid radical, fluoroborate, hexafluorosilicate or cyanide, in an electrolytic cell, to electrolytic dissolution of the anode with metallic bismuth as the anode.

Abstract: A method and apparatus for enriching the chromium concentration in an operating chrome plating from a spent chrome plating solution containing hexavalent chromium, trivalent chromium and extraneous metal ions is dislosed. A spent platining solution vessel is divided into an anode chamber and a cathode chamber by a porous container. A hollow primary anode is provided in the anode chamber and a plurality of cathodes are provided in the cathode chamber. A circularly shaped secondary anode is provided in the cathode chamber surrounding the cathodes and porous container. The primary anode and cathodes are connected to a primary electric circuit and the secondary anode and the cathodes are connected to a secondary electric. Operating solution from an operating plating vessel containing hexavalent chromium at a pre-enriched concentration is pumped to the anode compartment and hexavalent chromium enriched anolyte is flowed from the anode compartment to the operating plating vessel.

Abstract: Disclosed is a process for supplying nickel ions for a nickel alloy electroplating bath so as to replenish nickel ions consumed as electroplating progresses. The process uses an electrolysis cell, which is equipped with a rotatable cathode in the form of a drum or a disk having a surface of titanium or hard chromium plating; and an anode made of a titanium basket in which sulfur-containing metallic nickel is contained. Spent electroplating solution is electrolyzed in the electrolysis cell to dissolve nickel in the anode basket into the solution as ions and deposit a part of the dissolved nickel on the cathode, which is removed therefrom as the cathode rotates, while the rest of the dissolved nickel remains in the solution. The solution thus replenished with nickel ions is reused for the electroplating. The process may also be used to provide cobalt ions to replenish a spent cobalt alloy electroplating solution.

Abstract: An ion exchange separation, recovery and regeneration process for the control of iron is disclosed that can replace the conventional bleed stream process used in copper electrowinning. The disclosed process minimizes the loss of cobalt from the electrowinning circuit and can effect a lowering of the total iron concentration in the electrolyte circuit with an associated increase in current efficiency. The process captures the iron as iron(III) on an ion exchange medium containing a plurality of --CH(PO.sub.3 R.sub.2).sub.2 or --C(PO.sub.3 R.sub.2).sub.2 -- groups through which the divalvent metal ions pass. The iron(III) is then reduced with copper(I) to form iron(II) that is freed from the exchange medium, thereby permitting regeneration of the medium.

Abstract: Method and apparatus for handling water used in plating processes to eliminate discharge of pollutants including a plating tank for chrome plating selected materials, at least one rinse tank which holds rinse water where parts from the plating tank are rinsed to remove chrome compounds used in the plating tank and transfer means to transfer water from the rinse tank to a purification tank where hydrazine is added to the rinse water in quantities sufficient to maintain selected pH in the water returned to one of the rinse tanks for precipitation of the chromic compounds to chromic hydroxide which can be easily filtered for disposal as a dry material. High quality water such as deionized water is added to the rinse tank to makeup lost water and a catalyst such as cobalt salt can be added to the purification tank to assist in reduction of the chromic compounds.

Abstract: The invention relates to a method for separating ferrous ions from an iron-containing tinning electrolyte on the basis of methanesulfonic acid or phenolsulfonic acid, comprising the following steps:(a) providing a concentrated tin and iron-containing electrolyte containing 0.75 mols/l or more methanesulfonic acid phenolsulfonic acid(b) agitating and cooling the concentrated electrolyte to temperatures at which an insoluble Fe-salt preciptates(c) separating the insoluble precipitate to recover an electrolyte with a reduced iron concentration.and a recovery plant for tinning electrolytes on the basis of methanesulfonic acid or phenolsulfonic acid wherein this method is employed.

Abstract: The invention relates to a process for electrolytic treatment of copper foil, comprising the steps of: (A) applying a voltage across an anode and cathode, wherein the anode and cathode are in contact with an electroplating composition containing a gelatin component; (B) removing organic particulate matter by contacting the electroplating solution containing the organic particulate matter with an adsorbent polymer; and (C) electrolytically treating the copper foil. The electroplating composition can additionally contain an active sulfur-containing component, such as thiourea.

Abstract: The present invention is to provide a method for treating sludge as a by-product of a process of tin electroplating a steel plate by means of a plating bath containing haloid ions, together with an equipment therefor. More specifically, by immersing the sludge in water prior to filtration, the residual sludge is subjected to alkali hydrolysis in the presence or absence of the ions of an alkali earth metal within a temperature range of 100.degree. to 400.degree. C., whereby cyanide compounds and fluoride compounds contained therein under environmental regulations are prepared into environmentally non-hazardous matters. By adjusting the filtrate to pH 7.5 to 10, the precipitate with the principal component of tin hydroxide is deposited to recover the tin components contained in the sludge. Furthermore, the recovered tin is refined into the metal tin, for recycling and use as the electrode by the plating.

Abstract: Closed recycle system for chromium plating solution, solution wastes from chromium plating and chromic acid cleaning water in chromium plating composed of a chromium plating chamber including a chromic acid mist recovery device in communication with a recovery vessel for recovering and liquefying chromic acid mists formed upon chromium plating, and a chromic acid mist cleaning tower in communication with the recovery vessel for cleaning chromic acid mists flowing from the chromic acid mist recovery device. The recovery vessel is preferably positioned underground, and also preferably positioned in the recovery vessel. Liquid wastes containing noxious substances formed in chromium plating factories are utilized, and generation of materials leading to public pollution is prevented.

Abstract: A method and a plant for regenerating zinc sulfate electrolyte in steel strip electrogalvanizing processes by precipitating dissolved iron from electrolyte circulating through a coating cell. A partial quantity of the circulating electrolyte to be regenerated is removed from the coating cell and the dissolved iron is oxidized to Fe.sup.3+ by a redox-controlled addition of oxidizing agents. Subsequently, by raising the pH value to the precipitation limit of Fe.sup.3+ by a controlled addition of a ZnO/water suspension or a ZnCO.sub.3 /water suspension, the dissolved iron is precipitated as sludge. Any excess ZnO or ZnCO.sub.3 is then dissolved by adding fresh electrolyte. The precipitated iron sludge is conducted through a suitable filter such as a filter press, a filter belt, a decanter, etc., and the precipitated iron is filtered out in this manner. Subsequently, the purified partial quantity of the electrolyte is returned to the coating cell.

Abstract: An apparatus for removing metal contained in a solution through chelation which includes a means for adding a surface active agent containing a hydrophobic group, a hydrophilic group and a chelating group to a metal containing solution held within a metal solution accommodating means. An electric field applying means is adapted to apply an electric field to the solution containing means and further means is provided for separating an aggregate from the metal contained solution.

Abstract: Method to prevent the exhaustion of acid copper plating baths (12) and to treat sewage or sludges (20) containing copper in an ionic form so as to recover metallic copper (39), the method including the addition (11) of a compound which keeps the concentration of iron below a critical value (for instance, 60 grs/lt. ), the compound causing precipitation of iron in the form of ferrous sulphate and thus preventing the co-deposition of crystals of ferrous sulphate and copper sulphate with a possible incorporation of organic impurities such as stearates (35) present in the acid copper plating baths (12).

Abstract: An ion exchange separation, recovery and regeneration process for the control of iron has been developed to replace the conventional bleed stream process used in copper electrowinning. The process minimizes the loss of cobalt from the electrowinning circuit and strips the iron into a sulfate-based solution suitable for leach solution makeup. In addition, this process can effect a lowering of the total iron concentration in the electrolyte circuit with an associated increase in current efficiency.

Abstract: A method for treating the waste stream resulting from electroless plating operations such as copper electroless plating. The waste stream is simultaneously treated with hydrogen peroxide and UV light to bring the level of contaminants below the discharge limit. In one embodiment, the waste stream is also diluted with rinse water from the plating process.

Abstract: An improved process for removal of metal ions from aqueous solutions is disclosed. Removal of metal ions from aqueous solution, particularly from metal plating waste streams, is achieved by the combined use of polyamines, at levels less than the stoichiometric amount of metal ion, and cation exchangers. Treatment of waste streams with low levels of triethylenetetramine followed by contact with a strong acid cation exchange resin is especially effective in the removal of copper from metal-containing waste streams.

Abstract: Provided is a method for regenerating cyanide from thiocyanate. The method comprises contacting the thiocyanate with an oxidizing gas containing ozone, generally a mixture of oxygen and ozone. The pH of the contacting medium is generally less than 7.0 to assure that HCN is the predominant species relative to CN.sup.-. The method has important applications to processes involving cyanidation procedures, such as gold leaching, plating and coal conversion.

Abstract: Disclosed is a method for removal of contaminants and replenishment of an electroless copper plating solution in order to allow reuse of the solution. Copper oxide is dissolved in the spent solution and this is followed by an electrodialysis which removes formate and carbonate ions.

Abstract: A process for removing dissolved oils and greases from an aqueous solution which also may contain dissolved heavy metals is provided wherein the aqueous solution is mixed with a source of ferrous ion and dithionite ion in a first step at acidic pH to reduce and permit removal of solid heavy metal, is present and to separate oils and greases from the aqueous solution. Solution from the first step if reacted in a second step with hydroxide slurries obtained from third and fourth steps. A second step solution from the second step is reacted in a third step with an alkali composition and a third solution. Optionally, the third solution is reacted with a chelating agent for iron and an oxidizer in a fourth step. A solution of chelated iron from the fourth step, when practical is disposed of. Oils and greases are recovered from the first step such as by skimming.

Abstract: A method of recovering and reproducing a tinning liquid containing Fe ions and other detrimental cations by the steps of removing cations from the tinning liquid by passing the tinning liquid or a diluted liquid of the tinning liquid through a strong-acid cation exchange resin to obtain a recovered acid, thereafter reproducing the strong-acid cation exchange resin and desorbing adsorbed cations into a solution containing an acid by passing the acid through the exchange resin to which the cations have been adsorbed, precipitating and separating Sn ions in the form of a precipitate of an Sn compound from the solution into which the cations have been desorbed while maintaining Fe ions as ions in this solution, mixing and dissolving the precipitate of the Sn compound or a compound reduced from the same in the recovered acid to reproduce and reuse the mixture of the Sn compound and the recovered acid as a tinning liquid, and discharging the solution containing Fe ions out of the system of the tinning liquid.

Abstract: Hexavalent chromium is removed from aqueous sodium nitrate solutions by reacting hexavalent chromium with an aqueous slurry consisting essentially of ferrous hydroxide and barium sulfate whereby the chromium is reduced to trivalent chromium and precipitated as chromic hydroxide. Adulterating compounds and unwanted ions are not introduced to the electrolytic solution.

Abstract: An electrolytic apparatus and process for the on-line regeneration of acid cupric chloride etching baths used in printed circuit board fabrication is described. The apparatus utilizes a regeneration process which exactly reverses the reaction Cu+CuCl.sub.2 .fwdarw.2CuCl in order that the copper metal etched into the system is completely removed while at the same time maintaining the concentration of cuprous and cupric chloride within the desired range. A preferred system utilizes a flow-through graphite or carbon anode and a flow-by cathode, allowing for more precise control of current/potential variables. The cell utilizes low operating voltage resulting in less waste heat generation and lower electrical costs and improved on-line process control, leading to improved operating efficiencies and reliability in terms of unscheduled maintenance and outages.

Abstract: Process and equipment for reforming and maintaining the chemistry of an electroless metal bath, particularly an electroless nickel bath is disclosed.

Abstract: A process for removing chromium from an aqueous electrolyte solution is disclosed. The process involves admixing with the solution an amount of a chromium-reducing compound and an amount of a precipitant for the anion of the chromium-reducing compound. The invention provides for substantially complete reduction of hexavalent chromium to trivalent chromium and the formation of an insoluble chromium-containing material without leaving unwanted ions in the aqueous electrolyte solution. The aqueous electrolyte solution is regenerated by adjustment of pH and electrolyte concentration.

Abstract: Methods, and various apparatus therefor, are disclosed for the electrolytic treatment of an acidic solution. Generally the method comprises: (a) providing an electrolytic cell, the cell comprising: (i) an anode chamber and an anode therein; (ii) a cathode chamber and a cathode therein; and (iii) a diaphragm. Usually the diaphragm is of a non-isotropic fibrous mat comprising 5-70 weight percent organic halocarbon polymer fiber in adherent combination with about 30-95 weight percent of finely divided inorganic particulate impacted into said fiber during fiber formation, the diaphragm having a weight per unit of surface area of about 3-12 kilograms per square meter. The method can continue by (b) introducing the acidic solution into the cell; (c) impressing a current on the anode and the cathode causing the migration of ions through the diaphragm; and (d) recovering a product of the electrolytic treatment from the anode chamber, or the cathode chamber, or from both chambers.

Abstract: The present invention is concerned with a method for selectively removing antimony and bismuth from an impure sulphuric acid solution containing at least 50 g/L of acid and some concentration of ferric ion (for example copper refinery electrolyte), is disclosed. The method involves contacting the impure solution with a sufficient quantity of finely divided metallic copper so as to prereduce all ferric ion present in the solution to the ferrous oxidation state. The prereduced solution is then contacted with a chelating resin. The method avoids the deleterious loading of ferric iron onto the ion exchange resin and prevents the return of excessive amounts of chloride ion with the purified electrolyte.

Abstract: A method for plating tin onto the surface of steel strip in an acidic electrolyte bath utilizing insoluble anodes is disclosed. Free acid in the bath is extracted from the bath and concentrated. Tin is dissolved in the concentrated extract and the extract is returned to the bath to replenish the tin in the bath.

Abstract: A process for removing dissolved heavy metal from an aqueous solution is provided where the aqueous solution is mixed with a source of ferrous ion and dithionite ion in a first step at acidic pH to reduce and permit removal of the heavy metal. Solution from the first step is reacted in a second step with hydroxide slurrys obtained from third and fourth steps. A second solution from the second step is reacted in a third step with an alkali composition and a third solution. The third solution is reacted with a chelating agent for iron and an oxidizer in a fourth step. A solution of chelated iron from the fourth step is disposed of.

Abstract: Cyanide present in aqueous streams, such as effluents from electroplating and gold mining operations is reduced or eliminated by contacting the cyanide-containing stream with oxygen and carbon dioxide in the presence of ferrous ions, nickelous ions or cobaltous ions. The oxygen may be provided by air or oxygen and the contacting is carried out 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.

Abstract: There is disclosed a system for treatment of wastewater effluent from a photographic process which produces a developer effluent, a bleach effluent and a fixer effluent. The system comprises a developer treatment zone, a bleach treatment zone and a fixer treatment zone. Within each zone, there are provided defined means of pH adjustment of the effluent and a defined electrolytic cell for electrolysis of the effluent. A process for conducting the system is also provided. The invention may be advantageously used to reduce the concentration of or eliminated chemicals contained in the effluent.

Abstract: A process and apparatus for regenerating a plating bath comprising trivalent chromium cations (a trivalent chromium bath). The bath can be continuously, or more preferably, periodically with an ion exchange resin, preferably a cation exchange resin. A useful apparatus comprises a plating tank containing a trivalent chromium plating bath in communication with an ion exchange bed continuing ion exchange resin.

Abstract: A process by which organo phosphonate and cupric ions may be removed from an electroplating bath containing contaminants. Excess acetate salt content causes precipitation of a copper/organo phosphonate (HEDP) precipitate which may be removed leaving the contaminants in solution.

Abstract: A method, and apparatus therefor, for the electrolytic treatment of an acidic solution which comprises: (a) providing an electrolytic cell, the cell comprising: (i) an anode chamber and an anode therein; (ii) a cathode chamber and a cathode therein; (iii) a diaphragm of a non-isotropic fibrous mat comprising 5-70 weight percent organic halocarbon polymer fiber in adherent combination with about 30-95 weight percent of finely divided inorganic particulate impacted into said fiber during fiber formation, the diaphragm having a weight per unit of surface area of about 3-12 kilograms per square meter; (b) introducing the acidic solution into the cell; (c) applying a DC voltage between the anode and the cathode causing the migration of ions through the diaphragm; and (d) recovering a product of the electrolytic treatment from the anode chamber, or the cathode chamber, or from both chambers.

Abstract: The total organic content (TOC) of an aqueous composition is reduced to 200 ppm or less by subjecting the composition to electrolysis whereby the pH of the composition at the start of the electrolysis is about 1.8 to about 7 to thereby electrolytically decompose organic materials contained in the aqueous composition.

Abstract: A system for electroplating a tin-bismuth alloy at near eutectic composition is disclosed. The system includes the plating bath and the process for initially preparing the bath as well as the process for plating an object with tin-bismuth alloy. The system further includes an apparatus for regulating the concentrations of tin and bismuth in the plating bath and the process by which the concentrations are controlled.

Abstract: There is disclosed a gas treatment method and apparatus for the treatment of exhaust gas from an electrochemical plating operation, particularly from a chromium plating operation, to remove therefrom essentially all liquid entrainment. The invention comprises containment of the vapor space over the electroplating baths and evacuating the contained vapor space, passing the gases from the vapor space through a water bath and discharging the gases from the water bath through a mist separator and a sub-micron porous filter. Preferably the mist separator and porous filter are separated by a vapor space to permit coalesced droplets to condense and separate from the gases before passing the gases through the porous filter.

Abstract: A process for precipitating and removing chromium compounds in which chromium is in the hexavalent state from aqueous liquids, particularly, alkaline earth metal or alkali metal chlorate-rich solutions containing chloride, chlorate, and bichromate ions produced by the electrolysis of brine. In the process, hydroxylamine, hydroxylamine sulfate, hydroxylamine formate or hydroxylamine hydrochloride is used as a reducing agent to react and co-precipitate at a neutral or acid pH with hexavalent chromium ions present in the aqueous liquid, the reaction and precipitation taking place, generally, at a pH of about 4.0 to about 6.5 and, a temperature of about 50.degree. C. to about 100.degree. C. Precipitated oxides and hydroxides of divalent and trivalent chromium can be removed, for instance, by filtration.

Abstract: This invention relates to a micro-effluent process for rinsing water and equipment for the same in industrial processing, especially in electroplating processing. The process of the present invention is characterized in that periodically tank-turning over, that is, at definite time intervals, the rinsing solution is transferred from the first rinse tank to a high level storage tank or to a working-tank (plating-tank), from the second rinse tank to the first rinse tank, and so on and so forth, at last from the last rinse tank to its preceding tank, and the empty last rinse tank is filled up by clean water with a flow rate of less than 400 l/h, or filled up with clean water periodically at a definite time interval same as that for tank-turning over.

Abstract: A sulfate scavenger for chromium-plating baths consists of barium chromate or dichromate or mixtures of the two, added either directly to the bath or as part of a replenishment mixture with chromic acid.

Abstract: A chrome plating facility having a chrome recovery system into which chrome bearing mist, swept from a chrome plating solution surface, is directed. The system comprises a chrome removal system and a chrome reclamation system. The removal system comprises structure defining surfaces for collecting chrome from the vapor flowing through the station, a second chrome removal station downstream from the first removal station and comprising second structure defining surfaces for collecting chrome from fluid flowing through the second station. The reclamation system recovers chrome from the removal system and comprises a solvent reservoir, solvent recirculating means for directing reservoir solvent onto the second chrome removal station surfaces for removing chrome therefrom and returning the solvent and chrome to the reservoir.

Abstract: The present invention relates to a method of completely recovering nickel and zinc metal from multiple plating process waste streams by first separating the waste streams into a clean, relatively constant flow and/or concentration fraction and a dirty, variable flow and/or concentration fraction. Metal is recovered from the clean fraction by ion-exchange so as to concentrate the extracted metals for direct return to the plating bath. The effluent from the ion-exchange step is then blended with the dirty, variable flow and concentration fraction. This blended flow is first neutralized and then precipitated in a two-stage process using a sodium hydroxide solution. The resultant slurry containing the metal precipitate is filtered to yield a filter cake containing recovered nickel and zinc. This filter cake can then be further processed to recover the metal for reintroduction into the plating bath or for other uses.

Abstract: A new method for purification of trivalent chromium electroplating baths contaminated with cationic metal ions is disclosed. In this purification process, the contaminated trivalent chromium is passed at the pH level of the bath through one or more columns containing an ion-exchange resin having the picolylamine group as the functional moiety. The cationic metal ions are preferentially bound to the resin while the trivalent chromium is passed through the resin with substantially no adsorption thereby purifying the electroplating bath. This process is preferably performed simultaneously with the electroplating process.

Abstract: A device and method for using the device for applyng and/or removing coating on workpieces are disclosed. The device comprises a medium conveying device and a container adapted to receive the workpieces. The container has an inlet line connected to a medium source, an outlet line connecting the container to a medium source, the medium source being positioned below the conveying device, and a control device which connects the inlet and outlet lines to the medium source. The conveying device is a vacuum pump incorporated in the outlet line of the container.

Abstract: A method of removing undesired ions, such as chlorine, hypochlorite, chromium, cyanide and heavy metal ions, from an aqueous preparation containing one or more of said ions consists of adding to the aqueous preparation an effective amount of magnesium bisulfite to inactivate the undesired ions and then adjusting the pH of the mixture to an appropriate pH. Compositions containing magnesium bisulfite and divalent and trivalent ions are disclosed.

Abstract: A plating system includes a plating tank and a separation tank connected in a closed loop. Toxic bubbles or fumes are generated during plating which rise above the plating solution in the plating tank. Venturi and/or vortex scrubbers scrub the bubbles as the solution is drained from the plating tank to the separation tank. The toxic fumes are sucked into the primary scrubbing tube while the solution is drained from plating tank into the separation tank. The fine fumes are then forced through the secondary scrubber/filter. The solution once in the separation tank is then pumped back into the plating tank.

Abstract: Acid is removed from cathodic electrocoating baths in which electroconductive substrates are being coated with cationic resins present in the form of aqueous dispersions, at least a portion of the coating bath being subjected to an ultrafiltration where the ultrafiltration membrane retains the cationic resin to form an ultrafiltrate which contains water, solvent, low molecular weight substances and ions and is at least partly recycled into the coating bath, by subjecting at least a portion of the ultrafiltrate to a specific electrodialysis treatment before returning it into the electrocoating bath.

Abstract: A two-stage process for treating anode slimes and other residues containing a substantial amount of nickel without significant dissolution of silver and/or selenium in a single autoclave is disclosed. The process comprises, in a first stage, leaching the anode slimes at 15-30% solids in dilute sulphuric acid at a pressure between 4.0 and 5.5 bars and a temperature between 155.degree. C. to 170.degree. C. in the absence of oxygen to solubilize nickel, and in a second stage, without performing a solid liquid separation, leaching the remaining solids at a pressure between 2 and 3.5, preferably about 2.8 bars and a temperature between 110.degree. and 140.degree. C., preferably about 120.degree. C. with oxygen sparging such that the final sulphuric acid concentration is not less than 50 gpl to solubilize copper and tellurium.

Abstract: An integrated process for heavy metal and cyanide removal in aqueous waste stream from plating processes wherein cyanide is oxidized by hypochlorite at approximately pH of 11.5 and hexavalent chromium is reduced to trivalent chromium at ambient temperature with ferrous sulfate at pH of 9.5; excess hypochlorite from cyanide destruction reacts with ferrous sulfate and additional ferrous sulfate is added to reduce hexavalent chromium to trivalent chromium to allow hydroxide co-precipitation with hydroxides of the ferric iron and hydroxides of copper, chromium, zinc, cadmium, manganese, etc., which are then separated by settling and filtration.

Abstract: A process and apparatus for regenerating a plating bath comprising trivalent chromium cations (a trivalent chromium bath). The bath can be continuously, or more preferably, periodically with an ion exchange resin, preferably a cation exchange resin. A useful apparatus comprises a plating tank containing a trivalent chromium plating bath in communication with an ion exchange bed continuing ion exchange resin.