Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/28—Treatment of water, waste water, or sewage by sorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/28—Treatment of water, waste water, or sewage by sorption
  • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/28—Treatment of water, waste water, or sewage by sorption
  • C02F1/288—Treatment of water, waste water, or sewage by sorption using composite sorbents, e.g. coated, impregnated, multi-layered
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/1601—Process or apparatus
  • C23C18/1617—Purification and regeneration of coating baths
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D21/00—Processes for servicing or operating cells for electrolytic coating
  • C25D21/16—Regeneration of process solutions

Definitions

• the present invention relates to the treatment of solutions containing dissolved metals and, more particularly, to the treatment of metal plating solutions to remove dissolved metal therefrom.
• Solutions for plating metal are well known in the art and are used in both electrolytic processes and electroless plating processes. In either case, the solutions necessarily contain a source of the metal plating ions along with various other materials required for the particular plating operation (e.g., complexing and reducing agents for electroless plating; brighteners, grain refiners, surfactants for electrolytic processes).
• a source of the metal plating ions along with various other materials required for the particular plating operation (e.g., complexing and reducing agents for electroless plating; brighteners, grain refiners, surfactants for electrolytic processes).
• plating solutions are used in plating processes, certain components thereof necessarily are consumed and depleted, thereby decreasing the efficiency of the plating solution. It is well known in the art to extend the useful life of operating plating solutions by periodically replenishing the solution with formulations containing the consumed -1— components (e.g., the source of metal ions). However, the plating solution, evenwith replenishing, eventually has to be replaced by a new solution. Moreover, addition of replenishing formulations adds to the volume of the plating bath, requiring decanting and disposal of excess solution. Still further, rinse waters used to wash plated parts eventually build up metal values and must be disposed of.
• formulations containing the consumed -1— components e.g., the source of metal ions
• a module for conducting that portion of the process involving deposition of dissolved metals from the waste solution In the module, the filter aid particles on which the catalytic metal is absorbed are arranged as a bed in the module for receiving a solution which has been pH-adjusted and to which reducing agent has been added (to cause the solution to function as an electroless plating solution) .
• a standpipe also is arranged in the module for removing solution which has contacted the seeder particles and from which metal values have been removed. The standpipe is arranged so as to remove solution from the bottom of the module, which solution is then moved up through the standpipe for exit at the top of the module.
• Difficulties with the foregoing system include the need for pH adjustment and reducing agent addition to the waste solution prior to treatment with the seeder particles.
• the preferred catalytic material is palladium, a very expensive material, and the palladium/filter aid material is provided with yet a further coating of, e.g., copper.
• the overall materials of use are quite expensive and the module is overly cumbersome and heavy.
• the proposed modular unit for effecting contact of solution with the seeder particles is overly complicated and expensive to construct, and does not easily lend itself to easy removal and replacement when the seeder particles become saturated with deposited metal.
• the module comprises a container having a perforate planar bottom portion and upstanding side walls extending from the periphery thereof.
• a perforate planar retaining member within the container, adjacent and substantially parallel to the bottom portion, is a perforate planar retaining member above which the impregnated absorbent particles are arranged, the size of the particles and the size of the openings in the retaining member being such as to substantially prevent the impregnated particles from passing therethrough.
• a solution containing dissolved metal is first passed through a dispersing (distributing) mechanism, which preferably is constructed as an integral part of the modular apparatus, and then passed downwardly through the closely-packed absorbent particles and, finally, out of the module through the perforate bottom portion of the container. From this point, if any additional metal removal is required, the solution can be directly passed downwardly through another modular apparatus of the same type described above, arranged immediately below the first apparatus, the perforate bottom portion of the first apparatus acting as the distributor for the solution before it contacts the bed of particles in the second apparatus.
• the important advantages of the present invention is the fact that the modular apparatus can be easily and economically constructed of inexpensive materials and does not require piping to remove solution from the module after it has passed through the bed of closely-packed absorbent particles.
• the bed is more efficiently used and undesired channeling and/or other flow irregularities are greatly minimized.
• the solution containing dissolved metals is a waste or spent solution generated in a plating process of the electroless type, such as a spent plating bath, excess decant from a replenished plating bath and rinse waters used to wash plated parts.
• a particularly preferred use for the present invention is in the treatment of waste or spent solutions generated in an electroless copper plating process.
• FIG. 1 is an illustration of one form of modular apparatus according to the invention, shown in cut-away view to permit viewing of the interior contents and elements.
• FIG. 2 is. an illustration of a combination of two modular units according to the invention, each shown in cut-away view to permit viewing of the interior contents and elements.
• a preferred single modular apparatus comprises an enclosed container having a bottom portion 10 and upstanding side walls 12.
• the side walls 12 are affixed to and contiguous with the outer periphery of bottom portion 10 and may, if desired, also extend some small, predetermined distance below the plane of the bottom portion.
• bottom portion 10 will be of circular or substantially circular shape but, of course, can be of any desired shape so as to provide for a square, rectangular, cylindrical, etc. container area.
• side walls 12 can be outwardly tapered from the bottom portion 10, an arrangement which facilitates stacking one module on top of another.
• Bottom portion 10 and side walls 12 may be constructed of any material which possesses structural rigidity and which is inert to the solution containing dissolved metals as well as to any by-products of any reactions occurring in the container.
• Preferred materials of construction are plastics such as polypropylene.
• the bottom portion 10 is of perforate construction, the perforation size and frequency not being critical so long as the solution passed through the container can exit through bottom portion 10 without undue restriction or hold-up.
• a planar retaining means 14 Arranged in the bottom portion of the container, substantially parallel to bottom portion 10, is a planar retaining means 14 which is of perforate or foraminous construction.
• This retaining means 14 generally will be shaped so as to be in contact about its periphery with side walls 12 and, if desired, may even directly rest upon bottom portion 10.
• Retaining means 14 may be constructed of any material offering a suitable degree of rigidity and inertness to the solutions, materials and compounds with which it will be in contact, and may, for example, be constructed of plastic or metal.
• Retaining means 14 is, as noted, perforate or foraminous.
• Impregnated absorbent particles 16 are comprised of inert porous absorbent material having a large contact surface area containing (impregnated within the pores thereof and/or deposited on the surface thereof) a metal or metal compound capable of triggering the decomposition of the solution in question to cause deposition therefrom, onto the particles, of the particular dissolved metal sought to be removed from the solution.
• the porous absorbent material preferably is carbon but may also consist of any other suitable porous material.
• the triggering metal or metal compound will, of course, vary depending upon the particular solution and dissolved metal in question.
• the triggering material may be ferrous chloride, ferric chloride, ferrous sulfate, cuprous chloride, cupric chloride, copper metal itself, cupric oxide or cuprous oxide.
• concentration of triggering metal in any particular absorbent particle is not critical per se, so long as a sufficient quantity of such triggering material is present throughout the closely-packed bed of absorbent material to catalyze the required degree of decomposition of the solution containing the dissolved metal.
• the impreganted absorbent particles 16 are, as noted, in closely-packed arrangement above retaining means 14 so as to insure adequate contact of solution therewith as it passes downwardly through the apparatus.
• a substantially planar dispering means 18 which is of perforate or foraminous, porous construction. Again, this element may be constructed of any suitably rigid, inert material inherently perforate or in which perforations can be made. Dispersing means 18 generally will be substantially contiguous about its periphery with side walls 12 so as to insure that solution must pass therethrough before contacting the absorbent particle bed. Dispersing means 18 serves to distribute solution across a substantial portion of the upper surface of the absorbent particle bed so that the bed is efficiently utilized and so as to minimize flow distribution irregularities such as channeling.
• FIG.1 Included in the construction of FIG.1 is a perforated planar cover element 20 spaced apart from and parallel to dispersing means 18. Cover element 20 serves to assist in the
• impregnated absorbent particles are prepared, for example, by soaking the absorbent particles in an aqueous solution or suspension of the triggering material, and other materials which may be required to assist solubility and impregnation, for a predetermined period of time.
• particles for use in removing copper from a copper-containing electroless plating waste stream have been prepared by dissolving 4.2 pounds of ferrous sulfate in 2.5 gallons of hot water (acidified with H-SO. to aid solubility). The dissolved ferrous sulfate is then added to 7 pounds of WHT . particulate carbon and cold water is added to just cover the surface of the carbon. After mixing, the mixture is permitted to sit for about 12 hours.
• the mixture is then added to a pre-constructed cylindrical modular apparatus using a 1/4-inch thick polypropylene filter as the retaining means (500 ⁇ holes, evenly spaced) which rests on the bottom portion of the container (also polypropylene, 1/4-inch holes, randomly spaced; side walls * also made of polypropylene; volume of container about 5 gallons).
• the mixture in the apparatus is allowed to drain for about one hour until no further liquid drains from the holes in the bottom portion.
• a perforate polypropylene filter of the same size and perforation as the retaining member is then placed on top of the carbon particles to act as a dispersing member. About 2 gallons of a 10%
• solution of caustic (50% rayon grade) is then poured through the dispersing member and allowed to drain for about one hour. 5 A top perforated cover (polypropylene) is then placed over the container.
• the impregnated absorbent particle bed may be pre-treated (e.g., as noted above with caustic) to
• the means for dispersing the solution prior to contact with the impregnated absorbent particles preferably is an integral part of the modular
• a distinct advantage of the apparatus of the invention is the ability to utilize two or more such units in series, in a stacked or nested arrangement. In this manner, a highly efficient removal of dissolved metal from the solution can be
• a serial, stacked arrangement facilitates removal and replacement of units which have become inefficient due to saturation of the particles with the depositing metal.
• the uppermost unit which receives the most concentrated dissolved metal-containing solution, will become saturated in time and can simply be removed from the stack while a fresh (or regenerated) unit is then added to the bottom of the stack, operation then continuing with solution being fed to the original second or middle unit.
• FIG. 2 A particularly preferred stacked arrangement is illustrated (for two units) in FIG. 2.
• this arrangement permits elimination of dispersing means integral with individual units, since perforated retaining means 14 and bottom portion 10 for a particular unit can serve as the means for dispersing flow prior to contact with the impregnated particles 16 in a lower unit.
• the units should be constructed and stacked in a manner which does not permit a module to rest direclty on the bed of impregnated particles in the module below it.
• one or more of the individual units may contain an integral dispersing means.
• a solution containing dissolved metal After a solution containing dissolved metal has passed through one or more of the modular units it generally can be discarded into effluent streams directly since its dissolved metal content is greatly reduced (e.g. less than 5 ppm) .
• the solution may be treated in any other manner if further purification or recovery of other materials therefrom is desired.
• the impregnated absorbent particles can, if desired, be treated to remove deposited metal therefrom or can be sold as is as scrap.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Water Supply & Treatment (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Environmental & Geological Engineering (AREA)
• Hydrology & Water Resources (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Inorganic Chemistry (AREA)
• Mechanical Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Electrochemistry (AREA)
• Analytical Chemistry (AREA)
• Removal Of Specific Substances (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Treatment Of Liquids With Adsorbents In General (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=24410350

Family Applications (1)

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• 1985
  • 1985-02-18 ZA ZA851239A patent/ZA851239B/xx unknown
  • 1985-02-19 AU AU39936/85A patent/AU3993685A/en not_active Abandoned
  • 1985-02-19 EP EP19850901236 patent/EP0183702A4/de not_active Withdrawn
  • 1985-02-19 WO PCT/US1985/000255 patent/WO1985004817A1/en not_active Ceased
  • 1985-02-19 JP JP60500949A patent/JPS61501896A/ja active Pending

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