US3843769A
Expired / Lapsed
US
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Process for removing hexavalent chromium from chlorate containing liquors
Assignee: Hooker Chemical Corp
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Filing: 1973-10-12
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Granted: 1974-10-22
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Expires: 1993-10-12
Abstract
Abstract A method has been devised for removing hexavalent chromium values from concentrated aqueous alkali metal chlorate solutions by treating said solutions with a soluble sulfide, neutralizing the treated mixture and thereafter separating an insoluble trivalent chromium product from the solution. Hypochlorites, when present, may be simultaneously removed from the chlorate solution by reaction with excess sulfide reagent.
Inventors
- 👤 H Partridge
- 👤 J Hildyard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 02:27
CPC Classifications
C; C01; C01B; C01B11/00; C01B11/12; C01B11/14; C01B11/145; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/911; Y10S210/912; Y10S210/913
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
20 words
A PROCESS FOR REMOVING HEXAVALENT CHROMIUM VALUES FROM ALKALINE AQUEOUS SOLUTIONS OF ALKALI METAL CHLORATES WHICH COMPRISES THE STEPS OF
Claim 2
Dependent Claim
20 words
A PROCESS FOR REMOVING HEXAVALENT CHROMIUM VALUES FROM ALKALINE AQUEOUS SOLUTIONS OF ALKALI METAL CHLORATES WHICH COMPRISES THE STEPS OF
Claim 3
Dependent Claim
35 words
TREATING A CONCENTRATED AQUEOUS SOLUTION OF AN ALKALI METAL CHLORATE HAVING A PH ABOVE 8 WITH AT LEAST ABOUT 3 MOLAR PROPORTIONS OF A WATER SOLUBLE SULFIDE PER MOLAR PROPORTION OF HEXAVALENT CHROMIUM COMPOUND PRESENT,
Claim 4
Dependent Claim
35 words
TREATING A CONCENTRATED AQUEOUS SOLUTION OF AN ALKALI METAL CHLORATE HAVING A PH ABOVE 8 WITH AT LEAST ABOUT 3 MOLAR PROPORTIONS OF A WATER SOLUBLE SULFIDE PER MOLAR PROPORTION OF HEXAVALENT CHROMIUM COMPOUND PRESENT,
Claim 5
Dependent Claim
22 words
NEUTRALIZING THE RESULTANT SOLUTIOON TO A PH OF ABOUT 4 TO ABOUT 5 THEREBY PRECIPITATING TRIVALENT CHROMIUM AS AN INSOLUBLE PRODUCT, AND
Claim 6
Dependent Claim
22 words
NEUTRALIZING THE RESULTANT SOLUTIOON TO A PH OF ABOUT 4 TO ABOUT 5 THEREBY PRECIPITATING TRIVALENT CHROMIUM AS AN INSOLUBLE PRODUCT, AND
Claim 7
Dependent Claim
22 words
neutralizing the resultant solution to a pH of about 4 to about 5 thereby precipitating trivalent chromium as an insoluble product, and
Claim 8
Dependent Claim
22 words
neutralizing the resultant solution to a pH of about 4 to about 5 thereby precipitating trivalent chromium as an insoluble product, and
Claim 9
Dependent Claim
13 words
The process of claim 1 wherein said alkali metal chlorate is sodium chlorate.
Claim 10
Dependent Claim
42 words
The process of claim 2 wherein the said solution is treated with an amount of soluble sulfide which is at least sufficient to reduce the hexavalent chromium values to the trivalent stage and also to react with any alkali metal hypochlorite present.
Claim 11
Dependent Claim
9 words
separating the insoluble trivalent chromium product from said solution.
Claim 12
Dependent Claim
9 words
separating the insoluble trivalent chromium product from said solution.
Claim 13
Dependent Claim
9 words
SEPARATING THE INSOLUBLE TRIVALENT CHROMIUM PRODUCT FROM SAID SOLUTION.
Claim 14
Dependent Claim
9 words
SEPARATING THE INSOLUBLE TRIVALENT CHROMIUM PRODUCT FROM SAID SOLUTION.
Claim 15
Dependent Claim
32 words
The process of claim 2 wherein the said solution is treated with at least about 6 mol proportions of soluble sulfide per mol proportion of hexavalent chromium compound present in said solution.
Claim 16
Dependent Claim
34 words
The process of claim 4 wherein the said solution is treated with from about 10 to about 20 mol proportions of soluble sulfide per mol proportion of hexavalent chromium compound present in said solution.
Claim 17
Dependent Claim
34 words
The process of claim 5 wherein the said solution is treated with from about 10 to about 13 mol proportions of sodium sulfide per mol proportion of hexavalent chromium compound present in said solution.
Claim 18
Dependent Claim
15 words
The process of claim 2 in which the said solution is treated with sodium bisulfide.
Claim 19
Dependent Claim
34 words
The process of claim 5 in which the said solution is treated with about 12 to about 13 mol proportions of sodium bisulfide per mol proportion of hexavalent chromium compound present in said solution.
Claim 20
Dependent Claim
36 words
The process of claim 5 wherein the said solution, after treatment with the soluble sulfide, and prior to separating the insoluble trivalent chromium product is adjusted to a pH between above about 5 and about 7.
Claim 21
Dependent Claim
22 words
The process of claim 1 wherein the process is carried out at a temperature of from about 40* to about 80* C.
Claim 22
Dependent Claim
15 words
The process of claim 10 wherein the process is carried out at about 65* C.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |