US3869386A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of heavy metal ions from plating wastes
Assignee: Schlage Lock Co LLC
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Filing: 1972-10-24
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Granted: 1975-03-04
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Expires: 1992-10-24
Abstract
Abstract Treatment of plating effluents, including at least chromium plating effluent and, in plants having it, zinc plating effluent as well as effluents from plating copper, cadmium, or nickel, removing from these effluents the heavy metal ions. Hexavalent chromium ions are removed directly, without first reducing them to trivalent forms, by adding barium acetate. When other plating effluents are treated, the formed barium compounds are used as a coagulant for their hydroxides, which may be formed by mixing any of these other effluents with the formed barium compound and adjusting the pH to the value enabling precipitation of the hydroxides. Sulfuric acid may be used for this pH adjustment, thereby also precipitating out any remaining barium ions in solution.
Inventors
- 👤 Wladyslaw Izdebski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:24
CPC Classifications
C; C02; C02F; C02F9/00; C02F1/00; C02F1/52; C02F1/5236; C02F1/54; C02F2101/00; C02F2101/10; C02F2101/16; C02F2101/18; C02F2101/20; C02F2101/22; C02F2103/00; C02F2103/16; Y; Y10; Y10S; Y10S204/00; Y10S204/13; Y10S210/00; Y10S210/902; Y10S210/911; Y10S210/912; Y10S210/913
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
46 words
A PROCESS FOR TREATING PLATING PLANT EFFLUENT CONTAINING HEXAVALENT CHROMIUM IONS TO REMOVE THE CHROMIUM IONS COMPRISING ADDING THERETO BARIUM ACETATE IN AN AMOUNT SUFFICIENT TO PRECIPITATE SUBSTANTIALLY ALL OF THE HEXAVALENT CHROMIUM IONS AS BARIUM CHROMATE AND SEPARATING THE BARIUM CHROMATE PRECIPITATE FROM THE SOLU-
Claim 2
Dependent Claim
46 words
A PROCESS FOR TREATING PLATING PLANT EFFLUENT CONTAINING HEXAVALENT CHROMIUM IONS TO REMOVE THE CHROMIUM IONS COMPRISING ADDING THERETO BARIUM ACETATE IN AN AMOUNT SUFFICIENT TO PRECIPITATE SUBSTANTIALLY ALL OF THE HEXAVALENT CHROMIUM IONS AS BARIUM CHROMATE AND SEPARATING THE BARIUM CHROMATE PRECIPITATE FROM THE SOLU-
Claim 3
Dependent Claim
49 words
The process of claim 1, including adding after completing the addition of barium acetate a solution containing a substance chosen from the group consisting of sulfuric acid and water-soluble sulfates in a slight excess, sufficient to precipitate the barium ions, and separating the barium sulfate precipitate from the solution.
Claim 4
Dependent Claim
37 words
The process of claim 2, wherein said substance is added before the step separating the barium chromate but after precipitating the barium chromate, and both the barium chromate and barium sulfate are separated simultaneously from the solution.
Claim 5
Dependent Claim
14 words
The process of claim 3 wherein the separating is done by settling and decanting.
Claim 6
Dependent Claim
13 words
The process of claim 3 wherein the separating step is done by filtration.
Claim 7
Dependent Claim
71 words
The process of claim 3, including adding a second plating effluent containing other heavy metal ions after the barium acetate has been added and mixed and before the separating step, and adjusting the pH of the mixture before separation so as to precipitate the hydroxide of the other heavy metal ions, said barium chromate and barium sulfate being used as coagulants to hasten separation of the precipitated hyroxides from the solution.
Claim 8
Dependent Claim
26 words
The process of claim 6 wherein said second plating effluent contains at least one metal chosen from the group consisting of zinc, copper, nickel, and cadmium.
Claim 9
Dependent Claim
122 words
A process for treating plating plant aqueous effluent containing hexavalent chromium ions as a soluble compound chosen from the group consisting of chromic acid and alkali metal and ammonium bichromates, to remove the chromium ions, comprising sequentially adding thereto an aqueous solution of barium acetate in an amount sufficient to precipitate substantially all of the hexavalent chromium ions as barium chromate, adding thereto in aqueous solution a substance chosen from the group consisting of sulfuric acid and the water-soluble sulfates in an amount sufficient to precipitate all remaining barium ions in solution as barium sulfate, and separating the barium chromate and barium sulfate precipitates from the solution, leaving a solution that can be disposed of more safely than the original said effluent.
Claim 10
Dependent Claim
122 words
A process for treating plating plant aqueous effluent containing hexavalent chromium ions as a soluble compound chosen from the group consisting of chromic acid and alkali metal and ammonium bichromates, to remove the chromium ions, comprising sequentially adding thereto an aqueous solution of barium acetate in an amount sufficient to precipitate substantially all of the hexavalent chromium ions as barium chromate, adding thereto in aqueous solution a substance chosen from the group consisting of sulfuric acid and the water-soluble sulfates in an amount sufficient to precipitate all remaining barium ions in solution as barium sulfate, and separating the barium chromate and barium sulfate precipitates from the solution, leaving a solution that can be disposed of more safely than the original said effluent.
Claim 11
Dependent Claim
78 words
The process of claim 8, including adding, after the step of adding the barium acetate and before the step of separating, at least one other plating effluent containing metal ions of at least one metal chosen from the groups consisting of zinc, nickel, copper, and cadmium, and adjusting the pH of the resulting mixtures to an amount where the hydroxide of each said metal can precipitate, said barium chromate and barium sulfate serving as coagulants for such hydroxide.
Claim 12
Dependent Claim
112 words
A process for treating aqueous plating plant effluents, in which there is a first effluent containing hexavalent chromium ions and a second effluent containing zinc ions that have been converted to sodium zincate, comprising the following steps: adding a solution of barium acetate to said first effluent in an amount sufficient to precipitate substantially all of the hexavalent chromium ions as barium chromate, mixing the resultant mixtures with said second effluent, adjusting the pH of this mixture of effluents to pH 8, to precipitate zinc hydroxide, said barium chromate acting as a coagulant to hasten coagulation of the zinc hydroxide and separating the precipitates barium chromate and zinc hydroxide from the solution.
Claim 13
Dependent Claim
112 words
A process for treating aqueous plating plant effluents, in which there is a first effluent containing hexavalent chromium ions and a second effluent containing zinc ions that have been converted to sodium zincate, comprising the following steps: adding a solution of barium acetate to said first effluent in an amount sufficient to precipitate substantially all of the hexavalent chromium ions as barium chromate, mixing the resultant mixtures with said second effluent, adjusting the pH of this mixture of effluents to pH 8, to precipitate zinc hydroxide, said barium chromate acting as a coagulant to hasten coagulation of the zinc hydroxide and separating the precipitates barium chromate and zinc hydroxide from the solution.
Claim 14
Dependent Claim
39 words
The process of claim 10, adding after completing addition of the barium acetate a substance chosen from sulfuric acid and the soluble sulfates in aqueous solution, to precipitate any barium ions remaining and in solution, removing the precipitate therefrom.
Claim 15
Dependent Claim
28 words
The process of claim 10 wherein said pH is adjusted to pH 8 by sulfuric acid, thereby also precipitating as barium sulfate and barium ions remaining in solution.
Claim 16
Dependent Claim
41 words
The process of claim 12, including adding at about the same time as said second effluent a third plating effluent containing at least one soluble salt of at least one metal chosen from the group consisting of copper, cadmium, and nickel.
Claim 17
Dependent Claim
22 words
The process of claim 10 wherein the separating comprises settling for at least one hour and then decanting, filtering the decanted liquid.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-03 | 1978-09-02 | 1979-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-03 | 1982-09-02 | 1983-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-03 | 1986-09-02 | 1987-03-04 | $7700.00 | Window Closed / Lapsed |