Patent US5767457A successfully refreshed from Google Patents.
Patent US4731187A successfully refreshed from Google Patents.
US4731187A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of heavy metals from waste water
Assignee: Miyoshi Yushi KK
•
Filing: 1986-07-22
•
Granted: 1988-03-15
•
Expires: 2006-07-22
Abstract
Abstract A heavy metal can be removed from waste water, in which the metal is contained as ions, by adding to the waste water a metal scavenger together with at least one of sodium monosulfide, sodium polysulfides and sodium hydrogensulfide to form a metal ion containing floc. The resulting floc is then removed from the waste water by filtration. The metal scavenger contains at least one carbodithio group and/or at least one carbodithioate salt group as N-substituents per molecule.
Inventors
- 👤 Masafumi Moriya
- 👤 Kazuo Hosoda
- 👤 Akira Nishimura
- 👤 Takao Imachi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:41
CPC Classifications
C; C01; C01G; C01G55/00; C01G55/001; C01G11/00; C01G11/003; C01G13/00; C01G13/003; C01G15/00; C01G15/003; C01G21/00; C01G21/003; C01G28/00; C01G28/001; C01G3/00; C01G3/003; C01G31/00; C01G31/003; C01G37/00; C01G37/003; C01G5/00; C01G5/003; C01G7/00; C01G7/003; C01G9/00; C01G9/003; C02; C02F; C02F1/00; C02F1/52; C02F1/5236; C02F1/5272; C22; C22B; C22B3/00; C22B3/20; C22B3/26; C22B3/34; Y; Y02; Y02P; Y02P10/00; Y02P10/20; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/911; Y10S210/912; Y10S210/913; Y10S210/914
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
132 words
A process for removing heavy metal ions in waste water comprising adding a metal scavenger containing at least one carbodithio group, at least one carbodithioate salt group or at least one carbodithio group and at least one carbodithioate salt group as N-substituents per mole and at least one sodium sulfide selected from the group consisting of sodium monosulfide, sodium polysulfides and sodium hydrogensulfide in a weight ratio of metal scavenger to sodium sulfide of from 20:80 to 98:2 to heavy metal ion containing waste water in an amount of from 0.7 to 4 mole equivalents based on the total amount of heavy metal ions in the waste water, adjusting the pH of the waste water to a pH of 4-9, forming a metal ion containing floc, and removing the floc by filtration.
Claim 2
Dependent Claim
132 words
A process for removing heavy metal ions in waste water comprising adding a metal scavenger containing at least one carbodithio group, at least one carbodithioate salt group or at least one carbodithio group and at least one carbodithioate salt group as N-substituents per mole and at least one sodium sulfide selected from the group consisting of sodium monosulfide, sodium polysulfides and sodium hydrogensulfide in a weight ratio of metal scavenger to sodium sulfide of from 20:80 to 98:2 to heavy metal ion containing waste water in an amount of from 0.7 to 4 mole equivalents based on the total amount of heavy metal ions in the waste water, adjusting the pH of the waste water to a pH of 4-9, forming a metal ion containing floc, and removing the floc by filtration.
Claim 3
Dependent Claim
31 words
A process according to claim 1, wherein the metal scavenger contains, as an N-substituent, at least one group seIected from the group consisting of alkyl groups, β-hydroxyalkyl groups and acyl group.
Claim 4
Dependent Claim
15 words
The process of claim 1 wherein said at least one sodium sulfide is sodium hydrogensulfide.
Claim 5
Dependent Claim
31 words
The process of claim 1 wherein said at least one sodium sulfide is a sodium polysulfide selected from the group consisting of sodium disulfide, sodium trisulfide, sodium tetrasulfide or sodium pentasulfide.
Claim 6
Dependent Claim
35 words
The process of claim 1 wherein the metal scavenger and sodium sulfide is added in a total amount of 0.9 to 1.5 mole equivalents based on the amount of metal ions in the waste water.
Claim 7
Dependent Claim
23 words
The process of claim 1 wherein the metal scavenger and the sodium sulfide are mixed together prior to adding to the waste water.
Claim 8
Dependent Claim
21 words
The process of claim 1 wherein the metal scavenger and the sodium sulfide are each added separately to the waste water.
Claim 9
Dependent Claim
33 words
The process of claim 1 wherein the metal removed from the waste water is selected from the group consisting of mercury, cadmium, zinc, lead copper, chromium, arsenic, gold, silver, platinum, vanadium and thallium.
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) | 1991-03-15 | 1991-09-14 | 1992-03-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-15 | 1995-09-14 | 1996-03-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-15 | 1999-09-14 | 2000-03-15 | $7700.00 | Window Closed / Lapsed |