Precipitation of siliceous pigment
Abstract
Abstract SMALL, FINELY DIVIDED, SILICEOUS PIGMENT IS PRECIPITATED UNDER CIRCUMSTANCES TO MINIMIZE OR REDUCE THE AMOUNT OF WATER WHICH IS PRESENT IN THE FILTER CAKE WHEN THE PRECIPITATED SILICATE IS FILTERED FROM THE AQUEOUS SOLUTION IN WHICH IT IS FORMED. THE PROCESS IS CONDUCTED BY ADDED ACID TO SODIUM SILICATE OR LIKE ALKALI METAL SILICATE UNDER CONDITIONS SUCH AS TO PRODUCE A FINELY DIVIDED, RECOVERABLE SILICA PIGMENT HAVING AN AVERAGE ULTIMATE PARTICLE SIZE BELOW ABOUT 500 ANGSTROMS, AND CONTROLLING THE TEMPERATURE OF THE SOLUTION DURRING ACIDIFICATION SO THAT A PORTION OF THE ACID IS ADDED TO ONE TEMPERATURE AND ANOTHER PORTION OF THE ACID IS ADDED AT A HIGHER TEMPERATUE, SUCH HIGHER TEMPERATURE BEING ESTABLISHED BEFORE ALL, AND PREFERABLY BEFORE A MAJOR PORTION, OF THE SILICA HAS BEEN PRECIPITATED FROM THE SOLUTION. AS A CONSEQUENCE OF THIS PROCESS, THE SILICA FILTER CAKE OBTAINED HAS A HIGHER CONCENTRATION OF SOLIDS AND THEREFORE A LOWER CONCENTRATION OF WATER.
Inventors
- 👤 R Chisholm
Bibliographic Details
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1976-01-09 | 1976-07-10 | 1977-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-09 | 1980-07-10 | 1981-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-09 | 1984-07-10 | 1985-01-09 | $7700.00 | Window Closed / Lapsed |