US4032622A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of concentrating sulfuric acid using a boiler of improved cast iron
Assignee: Hoechst AG
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Filing: 1976-10-27
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Granted: 1977-06-28
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Expires: 1996-10-27
Abstract
Abstract When distilling or boiling concentrated sulfuric acid in a vessel of gray cast iron the corrosion resistance of the apparatus is improved by using an alloy containing from 0.2 to 1.6 % of silicon 0 to 0.2 % of phosphorus 0.6 to 2.5 % of copper 0 to 3.5 % of nickel Besides the usual elements for gray cast iron and a graphite portion in a finely divided form in a pearlitic skeleton.
Inventors
- 👤 Helmold von Plessen
- 👤 Grete Petrich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:36
CPC Classifications
C; C22; C22C; C22C37/00; C22C37/10
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
71 words
In a process for concentrating sulfuric acid, using a concentrator the improvement wherein the sulfuric acid concentrator has therein sulfuric acid and the concentrator is of gray cast iron which consisting essentially of from 2.5 to 3.7% by weight of carbon, 0.2 to 1.6% by weight of silicon, 0.6 to 2.5% by weight of copper, 0 to 0.2% by weight of phosphorous, 0 to 3.5% by weight of nickel, balance iron.
Claim 2
Dependent Claim
71 words
In a process for concentrating sulfuric acid, using a concentrator the improvement wherein the sulfuric acid concentrator has therein sulfuric acid and the concentrator is of gray cast iron which consisting essentially of from 2.5 to 3.7% by weight of carbon, 0.2 to 1.6% by weight of silicon, 0.6 to 2.5% by weight of copper, 0 to 0.2% by weight of phosphorous, 0 to 3.5% by weight of nickel, balance iron.
Claim 3
Dependent Claim
32 words
The process as defined in claim 1 wherein the sulfuric acid in said concentrator is at boiling point of said acid when said acid is at a concentration of at least 95%.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-06-27 | 1980-12-27 | 1981-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-27 | 1984-12-27 | 1985-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-27 | 1988-12-27 | 1989-06-28 | $7700.00 | Window Closed / Lapsed |