IIIHIIII USOO55.71489A United States Patent 19 11) Patent Number: 5,571,489 Holsen Et Al
Total Page：16
File Type：pdf, Size：1020Kb
IIIHIIII USOO55.71489A United States Patent 19 11) Patent Number: 5,571,489 Holsen et al. (45) Date of Patent: Nov. 5, 1996 54) PROCESS FOR CHROMUM RECOVERY 4,349,514 9/1982 Watanabe et al. ........................ 423154 FROMAQUEOUS SOLUTIONS 4,446,026 5/1984 Beutier et al. ..... ... 42.3/54 4,704,259 11/1987 Lipsztajn ............ ... 42.3/55 75) Inventors: Thomas M. Holsen, Oak Forest; Jan 5,112,583 5/1992 Bruzzone et al. ... 42.3/55 5,120,523 6/1992 Nakao et al. ...... ... 423/22 R. Selman; Subbarao L. Guddati, 5,260,039 11/1993 Schwab et al. ........ ... 423/24 both of Chicago, all of Ill. 5,271,910 12/1993 van der Meer et al. ................. 423/55 73) Assignee: Illinois Institute of Technology, FOREIGN PATENT DOCUMENTS Chicago, Ill. 1249841 9/1967 Germany ............................... 423f472 54-043172 4/1979 Japan ........ ... 423/53 21 Appl. No.: 380,851 56-015883 2/1981 Japan ... 423,595 22 Filed: Jan. 27, 1995 57-135724 8/1982 Japan ....................................... 423/53 OTHER PUBLICATIONS (51) Int. Cl.' .......................... C01G 37/00; CO1G 37/14; COG 37/02; CO1B 11/00 West, T. S., "Liquid-Liquid Extraction Procedures in Inor (52) U.S. C. ............................... 423/53; 423/54; 423/58; ganic Analysis', Metallurigia, p. 47, Jul., 1956. 423/472; 423/595; 42.3/596; 42.3/597; 423/607 Primary Examiner-Steven Bos (58 Field of Search .................................. 423/53, 54,58, Attorney, Agent, or Firm-Speckman, Pauley & Fejer 423/61, 472,595,596,597, 607 57 ABSTRACT 56 References Cited A process for recovery of chromium in an aqueous solution U.S. PATENT DOCUMENTS comprising converting the chromium to chromyl chloride, Separating the chromyl chloride from the aqueous solution, 2,574,065 1f951 Schulein .................................. 423,595 2,793,937 5/1957 East ............. ... 423f472 either as a heavy underlayer, or by extraction into a solvent, 3,493,328 2,970 Nieuwenhuis .. 423/58 purifying the chromyl chloride, hydrolyzing the purified 3,843,769 Of 1974 Partridge et al. ... 423f472 chromyl chloride to form a solution, and drying or precipi 3,856,917 2/1974 Texier et al. ..... ... 423,596 tating the solution to form chromium, either as chromic acid 3,896,209 7/1975 Fournier et al. .......................... 423/53 or a chromate salt. 4,092,439 5/1978 Demazeau et al. ..................... 423,1607 4,242,127 121980 Miller et al. ............................. 423/24 12 Claims, 3 Drawing Sheets SPENT PLATING/RINSE H2SO4. SOLUTION RECYCLE CrO2Cl2 SYNTHESIS TO FINAL EXTRACTION TREATMENT CrO2Cl2 HC HYDROLYSIS RECYCLE CrO2Cl2 SEPARATION CHROMEUM SEPARATION U.S. Patent Nov. 5, 1996 Sheet 1 of 3 5,571,489 SPENT PLATING/RINSE H2SO4 SOLUTION RECYCLE CrO2Cl2 SYNTHESIS CrO2Cl2 TO FINAL EXTRACTION TREATMENT CrO2Cl2 HC HYDROLYSIS RECYCLE CrO2 C 2 SEPARATION CHROMUM SEPARATION FG.1 U.S. Patent Nov. 5, 1996 Sheet 2 of 3 5,571,489 100 90 an 8O s O - l X 70 60 60 70 80 90 00 VOLUME OF H2SO4 (mL) FIG.2 00 90 is 80 S >- 70 v100mLH2SO4 60 O 80mLH2SO4 O 60mLH2SO4 50 O 5 O 15 20 25 30 TEMPERATURE (°C) FIG.3 U.S. Patent Nov. 5, 1996 Sheet 3 of 3 5,571,489 OO 80 is 60 - L Sc O 100 ml H2SO4(10°C) 40 O 100 ml H2SO4(20°C) C 60 mL H2SO4(10°C) 0 60 mL H2SO4(20°C) 20 20 30 40 50 60 7O 80 VOLUME OF HOL(mL) FIG.4 s O - Do 50 7O 80 90 00 FIG.5 VOLUME OF H2SO4 (mL) 5,571,489 1 2 PROCESS FOR CHROMIUM RECOVERY U.S. Pat. No. 4,349,514 teaches a process for recovery of FROMAQUEOUS SOLUTIONS reusable chromic acid from a waste chromic acid solution containing impurities in which the solution containing the chromic acid is introduced into the cathode compartment in BACKGROUND OF THE INVENTION 5 an electro-dialysis process and free chromic acid or chro mate ions in the solution are transferred to the anode 1. Field of the Invention compartment. HSO is added to the heavy metallic ion This invention relates to a process for recovery of chro contained in the outlet solution, in which chronic acid ion mium from aqueous solutions, such as spent plating solu concentration is reduced, in order to convert chemical spe tions and rinse waters used in the electroplating industry. 10 cies of the contained metallic ion and increase the H" ion The process is a total recovery and recycle method for concentration. Chromate ions in the resultant solution are chromium from concentrated aqueous solutions which gen extracted into an organic phase by contact with an organic erates no chromium waste as in other known processes for solvent. Residual amounts of chromic acid ion remaining in chromium recovery, such as precipitation and ion exchange. the aqueous raffinate are extracted into an organic phase by 2. Description of Prior Art 15 a second organic solvent. Chromic acid solutions are used for chromium plating, for U.S. Pat. No. 5,120,523 teaches a method for dissolving the electrolytic stripping of copper, for the anodizing of a metal, including chromium, by contact of the metal with a aluminum, and for the passivation of cadmium, magnesium, quaternary ammonium compound and a halogenated hydro and zinc. The chromic acid baths are contaminated by the carbon or with a quaternary ammonium compound, a halo buildup of trivalent chromium, formed as a result of the genated hydrocarbon and polar solvent. reduction of chromic acids, and other heavy metals such as U.S. Pat. No. 5,271,910 teaches a process for treating aluminum, zinc, copper, and iron, which dissolve from the metal chloride wastes produced by chlorination of titanium pieces being treated. These contaminants have several det ore in which the metal chloride wastes are leached in a rimental effects on the plating solution including increased hydrochloric acid-containing solution; dissolved metals are voltages and plating times, increased pitting and noduling, 25 separated from the remaining solids in the solution to obtain and decreased current efficiency. In addition, as a result of a liquid and a residue; the metals are then selectively increased levels of contamination, the quality of the plating precipitated as their hydroxides by adding a neutralizing deteriorates and a portion of the bath must be discarded, agent to the liquid; and the metal hydroxides thus obtained even though it still contains large amounts of chromic acid. are separated from the liquid to produce a residue which is Spent plating solutions from these processes present a major 30 subsequently dewatered. waste treatment problem. U.S. Pat. No. 5,260,039 teaches a process for two-phase Known methods for the recovery and use of hexavalent extraction of metal ions from phases containing solid metal chromium include ion exchange, reverse osmosis, electrodi oxides in which the solid metal oxides are brought into alysis, ion flotation, and chemical means. Known methods contact with a hydroxamic acid, dissolved in a hydrophobic for the removal and destruction of hexavalent chromium in 35 organic solvent, the phases containing the solid metal oxides industrial effluents include reduction-precipitation, selective and the organic phase being intensively mixed. After phase pyrolysis, electro-coagulation, incineration, organic com splitting, the organic phase is separated and the metal ions plexation, foam and ion flotation, and chemical methods. are re-extracted from the organic phase in a known manner. U.S. Pat. No. 5,112,583 teaches a process for recovering U.S. Pat. No. 4,242,127 teaches a method for processing chromic anhydride from exhausted aqueous chromium plat 40 a hydroxide sludge residue to recover nonferrous metal ing solutions by alkalizing the exhausted chromium plating values therefrom which includes the steps of concentrating liquid to a pH comprised between three (3) and seven (7) at the residue and acidifying and heating the concentrated a temperature of 70° C. with a commercial sodium hydrox residue to produce a solution containing the nonferrous ide solution, keeping the mass in reaction at this temperature metals followed by separation of the nonferrous metals, for an hour, followed by filtration to separate the precipitate 45 including chromium, by high temperature pressure hydroly formed. The filtered solution contains CrO which is then sis to obtain the metals as hydrated oxides or basic sulfates. reduced with sulfur dioxide to obtain a solution containing Finally, U.S. Pat. No. 4,092,439 teaches a process for basic chromium sulfate and sodium sulfate, suitable for use preparation of chromium dioxide by oxidizing hydrated as a tanning bath. 50 trivalent chromium oxide. See also West, T. S., "Liquid U.S. Pat. No. 4,704,259 teaches a process for the removal Liquid Extraction Procedures in Inorganic Analysis', Met of chromium in the form of chromate from electrolytically allurigia, Page 47, July 1956, which presents a general produced aqueous chlorate solutions by the formation and overview of liquid-liquid extraction procedures in inorganic precipitation of Cr' as Cr(OH) by reduction of hexavalent analysis including methods for extraction of chromium. chromium with a dithionite. In particular, hydroxyl ions are 55 Of all of the known methods, ion-exchange is considered added to an aqueous chlorate solution in a sufficient amount to be the most efficient means of hexavalent chromium to provide alkaline pH conditions and to permit trivalent recovery and reuse from rinse solutions. However, this chromium to form Cr(OH), followed by an addition of method is not feasible at higher concentrations of chromic dithionite to cause precipitation of Cr(OH), after which the acid. Reduction-precipitation is generally considered the precipitated Cr(OH) is separated from the aqueous chlorate 60 easiest means of destruction of hexavalent chromium in Solution.