Production of alumina and portland cement from clay and limestone
Abstract
Abstract Alumina is extracted from kaolin-type clays by admixing the clay with calcium oxide in an amount sufficient to obtain the mole ratios of CaO:Al2O3 within the range of from about 0.8/1 to about 1.2/1, and of CaO:SiO2 from about 1.8/1 to about 2.2/1; calcining the mixture at about 1,300* C.; digesting the clinker with sodium carbonate; following the removing of the solid residue from the digestion solution, aluminum trihydrate is precipitated in the crystalline form of Gibbsite by treatment of the solution with carbon dioxide at elevated temperatures; and the precipitate is calcined to recover the desired alumina. The residue from the digestion step is used to form low-aluminate-containing portland cement.
Inventors
- 👤 Richard L Angstadt
- 👤 Russell N Bell
Bibliographic Details
Claims Analysis
Total Claims: 4References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |