US3974254A
Expired / Lapsed
US
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Process for purifying metallurgical gases containing sulphurous anhydride by extracting mercury
Assignee: Patronato de Investigacion Cientifica y Tecnica
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Filing: 1973-12-10
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Granted: 1976-08-10
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Expires: 1993-12-10
Abstract
Abstract The present invention relates to a process for purifying metallurgical gases containing sulphuric anhydride by extracting mercury, using the sulphurous anhydride which accompanies the metallurgical gases as an oxidizing agent for the mercury, an additional contribution of sulphurous anhydride being made when the latter is deficient, and employing in addition an acid to facilitate the oxidization of the mercury and a soluble thiocyanate in order to complete the oxidation of the mercury.
Inventors
- 👤 Antonio de la Cuadra Herrera
- 👤 Miguel Fernandez Tallante
- 👤 Armando Rodriguez Sanchez
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:15
CPC Classifications
C; C22; C22B; C22B43/00
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
83 words
A process for purifying metallurgical gases by extracting mercury from such gases containing sulphurous anhydride comprising contacting the gases with a thiocyanate dissolved in an aqueous sulphuric acid solution, oxidizing the mercury by means of the sulphurous anhydride being present in an amount sufficient to act as an oxidizing agent for the mercury to be extracted, the sulfuric acid solution having an acidity sufficient to facilitate the oxidation of the mercury and the thiocyanate completing the oxidation of the mercury to be extracted.
Claim 2
Dependent Claim
83 words
A process for purifying metallurgical gases by extracting mercury from such gases containing sulphurous anhydride comprising contacting the gases with a thiocyanate dissolved in an aqueous sulphuric acid solution, oxidizing the mercury by means of the sulphurous anhydride being present in an amount sufficient to act as an oxidizing agent for the mercury to be extracted, the sulfuric acid solution having an acidity sufficient to facilitate the oxidation of the mercury and the thiocyanate completing the oxidation of the mercury to be extracted.
Claim 3
Dependent Claim
19 words
A process as claimed in claim 1 wherein the extracted mercury in the solution is separated therefrom by precipitation.
Claim 4
Dependent Claim
26 words
A process as claimed in claim 2 wherein the precipitation of the extracted mercury is obtained by adding a solution of sodium sulfide to the solution.
Claim 5
Dependent Claim
48 words
A process as claimed in claim 2 wherein the extracting solution is recycled to the extraction process after the extracted mercury therein has been precipitated and after the thiocyanate and acid concentrations have been adjusted to their original values required for carrying out the mercury extraction by oxidation.
Claim 6
Dependent Claim
21 words
A process as claimed in claim 1 wherein the concentration of extracted mercury in the solution ranges up to 5 g/l.
Claim 7
Dependent Claim
40 words
A process as claimed in claim 1 wherein the sulphuric acid is in a concentration in the solution in the range of 2 g/l up to that amount which may be added without effecting solution stability under the process conditions.
Claim 8
Dependent Claim
15 words
A process as claimed in claim 6 wherein the sulphuric acid concentration is 50 g/l.
Claim 9
Dependent Claim
37 words
A process as claimed in claim 1 wherein the concentration of thiocyanate dissolved in the solution is in the range of 2 g/l up to that amount which produces saturation of the solution at the process temperature.
Claim 10
Dependent Claim
15 words
A process as claimed in claim 8 wherein the concentration of thiocyanate is 150 g/l.
Claim 11
Dependent Claim
42 words
A process as claimed in claim 1 wherein additional sulphurous anhydride is added to that already contained in the metallurgical gases from which mercury is to be extracted to provide an amount sufficient to act as an oxidizing agent for the mercury.
Claim 12
Dependent Claim
26 words
A process as claimed in claim 1 wherein the concentration of sulphurous anhydride is in the range of 1-6 percent, based on volume, of the gases.
Claim 13
Dependent Claim
30 words
A process as claimed in claim 1 wherein the concentration of mercury in the metallurgical gases is in the range 5 mg to 20 g per m 3 of gas.
Claim 14
Dependent Claim
25 words
A process as claimed in claim 1 wherein the mercury remaining in the gases after extraction is below 5 mg per m 3 of gas.
Claim 15
Dependent Claim
21 words
A process as claimed in claim 1 wherein the temperature of the gases is in the range of 10° to 100°C.
References Cited (Backward Citations)
US3145080A
Cited
US3695838A
Cited
US3701651A
Cited
US3689217A
Cited
US3838190A
Cited
US3826819A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-10 | 1980-02-09 | 1980-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-10 | 1984-02-09 | 1984-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-10 | 1988-02-09 | 1988-08-10 | $7700.00 | Window Closed / Lapsed |