US4680126A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Separation and recovery of reusable heavy metal hydroxides from metal finishing wastewaters
Assignee: Individual
•
Filing: 1986-02-18
•
Granted: 1987-07-14
•
Expires: 2006-02-18
Abstract
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.
Inventors
- 👤 James M. Frankard
- 👤 Orville V. Broch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:36
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/66; C25; C25D; C25D21/00; C25D21/16; C25D21/20; C02F2101/00; C02F2101/10; C02F2101/16; C02F2101/18; C02F2101/20; C02F2101/203; C02F2101/22; Y; Y10; Y10S; Y10S204/00; Y10S204/13; Y10S210/00; Y10S210/902; Y10S210/911; Y10S210/912; Y10S210/913
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
159 words
A method for treating wastewaters and sludges from a plating process to facilitate reuse of metal values by the recovery of non-ferrous metal hydroxide, said method comprising the following steps (a) through (f) in the order presented: (a) lowering the pH of an aqueous slurry obtained from a plating process from an alkaline pH to an acid pH, said slurry comprising solid ferrous hydroxide and a solid non-ferrous metal hydroxide wherein the non-ferrous metal is selected from the group consisting of zinc, nickel, copper (ii) cadmium, and chromium (III) to dissolve the non-ferrous metal hydroxide; (b) converting the ferrous hydroxide to solid ferric hydroxide by aeration of the aqueous acidic slurry; (c) isolating the solid ferric hydroxide from the slurry leaving a solution comprising non-ferrous metals; (d) raising the pH of the solution of step (c) to precipitate non-ferrous metal hydroxide; (e) recovering the precipitated non-ferrous metal hydroxide; and (f) introducing said non-ferrous metal hydroxide into the plating process.
Claim 2
Independent Claim
159 words
A method for treating wastewaters and sludges from a plating process to facilitate reuse of metal values by the recovery of non-ferrous metal hydroxide, said method comprising the following steps (a) through (f) in the order presented: (a) lowering the pH of an aqueous slurry obtained from a plating process from an alkaline pH to an acid pH, said slurry comprising solid ferrous hydroxide and a solid non-ferrous metal hydroxide wherein the non-ferrous metal is selected from the group consisting of zinc, nickel, copper (ii) cadmium, and chromium (III) to dissolve the non-ferrous metal hydroxide; (b) converting the ferrous hydroxide to solid ferric hydroxide by aeration of the aqueous acidic slurry; (c) isolating the solid ferric hydroxide from the slurry leaving a solution comprising non-ferrous metals; (d) raising the pH of the solution of step (c) to precipitate non-ferrous metal hydroxide; (e) recovering the precipitated non-ferrous metal hydroxide; and (f) introducing said non-ferrous metal hydroxide into the plating process.
Claim 3
Dependent Claim
33 words
The method of claim 1 wherein the isolated solid ferric hydroxide of step (c) is washed with dilure aqueous acid and the aqueous acid is added to the aqueous slurry of step (a).
Claim 4
Dependent Claim
56 words
The method of claim 1 wherein the non-ferrous metal hydroxide comprises a mixture of zinc hydroxide and a second hydroxide of nickle, cooper (II), cadmium or chromium (II); and wherein in step (d) the pH of the slurry is raised to above 12.0 to maintain the zinc hydroxide in solution while precipitating the second metal hydroxide.
Claim 5
Dependent Claim
18 words
The method of claim 3 whe the pH of the slurry is raised to about 12-13.5 step (d).
Claim 6
Dependent Claim
21 words
The method of claim 4 further comprising lowering the pH of the slurry to precipitate the zinc hydroxide following step (e).
Claim 7
Dependent Claim
16 words
The method of claim 5 wherein the pH is lowered to about 7-11 following step (e).
Claim 8
Dependent Claim
13 words
The method of claim 1 wherein the non-ferrous metal hydroxide comprises zinc hydroxide.
Claim 9
Dependent Claim
16 words
The method of claim 7 wherein the pH is lowered to about 3-7 in step (a).
Claim 10
Dependent Claim
16 words
The method of claim 7 wherein the pH is raised to about 7-11 in step (d).
Claim 11
Dependent Claim
13 words
The method of claim 1 wherein the non-ferrous metal hydroxide comprises nickel hydroxide.
Claim 12
Dependent Claim
16 words
The method of claim 10 wherein the pH is lowered to about 3-7 in step (a).
Claim 13
Dependent Claim
16 words
The method of claim 10 wherein the pH is raised to about 8-14 in step (d).
Claim 14
Dependent Claim
14 words
The method of claim 1 wherein the non-ferrous metal hydroxide comprises copper (II) hydroxide.
Claim 15
Dependent Claim
16 words
The method of claim 13 wherein the pH is lowered to about 3-7.0 in step (a).
Claim 16
Dependent Claim
16 words
The method of claim 13 wherein the pH is raised to about 8.0-14.0 in step (d).
Claim 17
Dependent Claim
13 words
The method of claim 1 wherein the non-ferrous metal hydroxide comprises cadmium hydroxide.
Claim 18
Dependent Claim
16 words
The method of claim 16 wherein the pH is lowered to about 3.0-7.0 in step (a).
Claim 19
Dependent Claim
16 words
The method of claim 16 wherein the pH is raised to about 7-14 in step (d).
Claim 20
Dependent Claim
14 words
The method of claim 1 wherein the non-ferrous metal hydroxide comprises chromium (III) hydroxide.
Claim 21
Dependent Claim
16 words
The method of claim 19 wherein the pH is lowered to about 3-5 in step (a).
Claim 22
Dependent Claim
16 words
The method of claim 19 wherein the pH is raised to about 5.75-14 in step (d).
Claim 23
Independent Claim
132 words
A method for treating wastewaters and sludges from a plating process to facilitate reuse of metal values by the recovery of zinc hydroxide, said method comprising the following steps (a) through (f) in the order presented: (a) lowering the pH of an aqueous slurry obtained from a plating prodess from an alkaline pH to an acid pH, said slurry comprising solid ferrous hydroxide and solid zinc hydroxide, to dissolve the zonc hydroxide; (b) converting the ferrous hydroxide to solid ferric hydroxide by aeration of the aqueous acidic slurry; (c) isolating the solid ferric hydroxide from the slurry leaving a solution comprising zinc; (d) raising the pH of the solution of step (c) to precipitate zinc hydroxide; (e) recovering the precipitated zinc hydroxide; and (f) introducing said zonc hydroxide into the plating process.
Claim 24
Independent Claim
132 words
A method for treating wastewaters and sludges from a plating process to facilitate reuse of metal values by the recovery of zinc hydroxide, said method comprising the following steps (a) through (f) in the order presented: (a) lowering the pH of an aqueous slurry obtained from a plating prodess from an alkaline pH to an acid pH, said slurry comprising solid ferrous hydroxide and solid zinc hydroxide, to dissolve the zonc hydroxide; (b) converting the ferrous hydroxide to solid ferric hydroxide by aeration of the aqueous acidic slurry; (c) isolating the solid ferric hydroxide from the slurry leaving a solution comprising zinc; (d) raising the pH of the solution of step (c) to precipitate zinc hydroxide; (e) recovering the precipitated zinc hydroxide; and (f) introducing said zonc hydroxide into the plating process.
Claim 25
Dependent Claim
21 words
The method of claim 22 wherein the pH of the aqueous slurry in step (a) is about 8-11 prior to lowering.
Claim 26
Dependent Claim
32 words
The method of claim 22 wherein the isolated solid ferric hydroxide from step (c) is washed with dilute aqueous acid and the aqueous acid is added to the slurry of step (a).
Claim 27
Dependent Claim
16 words
The method of claim 22 further comprising thermally converting the recovered zinc hydroxide to zinc oxide.
Claim 28
Dependent Claim
16 words
The method of claim 22 wherein the pH is lowered to about 4-5.5 in step (a).
Claim 29
Dependent Claim
20 words
The method of claim 26 in the pH is lowered by combining the slurry with sulfuric acid or hydrochloric acid.
Claim 30
Dependent Claim
18 words
The method of claim 26 the pH is raised by combining the slurry with an alkali metal hydroxide.
Claim 31
Dependent Claim
16 words
The method of claim 22 wherein the pH is raised to about 8.5-9.5 in step (d).
References Cited (Backward Citations)
GB989813A
Cited
US3800024A
Cited
US3725266A
Cited
US3784669A
Cited
US3931007A
Cited
US4163716A
Cited
US4025430A
Cited
US4018680A
Cited
US4171255A
Cited
US4338200A
Cited
US4282190A
Cited
US4343706A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-07-13 | 1991-01-12 | 1991-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-07-13 | 1995-01-12 | 1995-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-07-13 | 1999-01-12 | 1999-07-14 | $7700.00 | Window Closed / Lapsed |