US3965243A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recovery of sodium thiocyanate
Assignee: David Krofchak Ltd
•
Filing: 1974-09-10
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Granted: 1976-06-22
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Expires: 1994-09-10
Abstract
Abstract A process is described whereby accumulated impurities, consisting mainly of sodium tiocyanate are continuously removed from scrubbing liquors used for removal of hydrogen sulphide from fuel gases and the liquors thereby regenerated and re-used in the hydrogen sulphide scrubbing operation. The thiocyanate is removed by contacting the used scrubbing liquor with an organic solvent, e.g. n-butanol, separating the thiocyanate-bearing solvent from the scrubbing liquor, re-using the treated scrubbing liquor, recovering the thiocyanate from the solvent and re-using the solvent. The extracted sodium thiocyanate can be converted to pure, saleable chemicals or converted to an alkali which can be re-used in the absorbing liquors, thereby producing a completely closed system with no effluent.
Inventors
- 👤 David Krofchak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:48
CPC Classifications
C; C01; C01C; C01C3/00; C01C3/20; C10; C10K; C10K1/00; C10K1/08; C10K1/10; C10K1/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
110 words
A process for the regeneration of an aqueous alkaline scrubbing liquor which has been used for removal of hydrogen sulphide from fuel gas and which contains alkali thiocyanate which comprises contacting at least a portion of said liquor with an organic extractant for said alkali thiocyanate, said extractant consisting essentially of n-butanol, separating the aqueous phase comprising scrubbing liquor of reduced alkali thiocyanate content from the alkali thiocyanate bearing organic extractant, recycling said liquor of reduced alkali thiocyanate content for re-use as gas scrubbbing liquor, separating alkali thiocyanate from said alkali thiocyanate bearing organic extractant to regenerate said extractant and recycling said regenerated extractant to treat additional used scrubbing liquor.
Claim 2
Dependent Claim
110 words
A process for the regeneration of an aqueous alkaline scrubbing liquor which has been used for removal of hydrogen sulphide from fuel gas and which contains alkali thiocyanate which comprises contacting at least a portion of said liquor with an organic extractant for said alkali thiocyanate, said extractant consisting essentially of n-butanol, separating the aqueous phase comprising scrubbing liquor of reduced alkali thiocyanate content from the alkali thiocyanate bearing organic extractant, recycling said liquor of reduced alkali thiocyanate content for re-use as gas scrubbbing liquor, separating alkali thiocyanate from said alkali thiocyanate bearing organic extractant to regenerate said extractant and recycling said regenerated extractant to treat additional used scrubbing liquor.
Claim 3
Dependent Claim
29 words
The process according to claim 1, wherein the used liquor is an alkaline solution of 2:7 anthraquinone disulphonic acid and sodium vanadate and the alkali thiocyanate is sodium thiocyanate.
Claim 4
Dependent Claim
72 words
The process according to claim 1 in which the extracted alkali thiocyanate is sodium thiocyanate which is hydrolyzed in a molten state with steam at 500°-800°F. to produce sodium carbonate and gases which are returned to the fuel gas being treated, the residue from said hydrolysis operation is extracted with solvent to remove unconverted sodium thiocyanate, and the sodium carbonate is returned with the recycled scrubbing liquor of reduced alkali thiocyanate content.
Claim 5
Dependent Claim
44 words
The process according to claim 1, in which at least some of the extracted alkali thiocyanate is filtered, passed through activated carbon, crystallized, dried, dissolved in solvent, filtered, recrystallized and dried to produce pure sodium thiocyanate and to remove other salts from the system.
Claim 6
Dependent Claim
22 words
The process according to claim 1 in which the scrubbing liquor is Stretford liquor and the fuel gas is coke oven gas.
References Cited (Backward Citations)
SU199123A1
Cited
US1570047A
Cited
US2386985A
Cited
US2621108A
Cited
GB948270A
Cited
US3652203A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-06-22 | 1979-12-22 | 1980-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-22 | 1983-12-22 | 1984-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-22 | 1987-12-22 | 1988-06-22 | $7700.00 | Window Closed / Lapsed |