Patent US3159497A successfully refreshed from Google Patents.
US3159497A
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US
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Method of improving the grade of byproduct gypsum obtained in carrying out a wet process for production of phosphoric acid
Assignee: Taiheiyo Cement Corp
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Filing: 1961-10-02
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Granted: 1964-12-01
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Expires: 1981-10-02
Abstract
No abstract record available.
Inventors
- 👤 Yamaguchi Taro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:06
CPC Classifications
C; C04; C04B; C04B11/00; C04B11/02; C04B11/024; C01; C01B; C01B25/00; C01B25/16; C01B25/18; C01B25/22
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
194 words
A METHOD OF IMPROVING THE GRADE OF BY-PRODUCT GYPSUM OBTAINED BY A WET PROCESS FOR MANUFACTURING PHOSPHORIC ACID AND CONTAINING FREE PHOSPHORIC ACID, WHICH COMPRISES THE STEPS OF FORMING A MIXTURE OF SAID BY-PRODUCT GYPSUM, AT LEAST ONE ADDITIVE SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF CALCIUM OXIDE, CALCIUM HYDROXIDE, CALCIUM CARBONATE, MAGNESIUM HYDROXIDE, MAGNESIUM CARBONATE, POWDER PRODUCED FROM PORTLAND CEMENT CLINKER, PORTLAND CEMENT, FLUE DUST PRODUCED FROM CEMENT KILN OPERATION, PULVERIZED SLAG PRODUCED FROM BLAST URNACE OPERATION, IRON HYDROXIDE, IRON OXIDE, ALUMINUM HYDROXIDE AND ALUMINUM OXIDE IN THE AMOUNT OF FROM 2 TO 6 TIMES THE AMOUNT THEORETICALLY REQUIRED TO NEUTRALIZE AND CONVERT THE TOTAL PHOSPHORIC ACID CONTAINED IN THE BY-PRODUCT GYPSUM INTO INERT PHOSPHATES, AND AT LEAST ONE BASIC SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF CAUSTIC ALKALI, AMMONIA AND SODIUM CARBONATE, SUBJECTING SAID MIXTURE TO HEATING WITH STEAM UNDER PRESSURE AT A TEMPERATURE OF FROM 120 TO 200*C., THEREBY TO FORM ONE SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF HALF-HYDRATED GYPSUM, ANHYDROUS GYPSUM AND MIXTURES THEREOF, AND SUBJECTING SAID SUBSTANCE THUS PRODUCED TO HYDRATION IN THE PRESENCE OF WATER THERBY TO FORM DIHYDRATED GYPSUM CONTAINING SAID AT LEAST ONE ADDITIVE SUBSTANCE.
Claim 2
Independent Claim
194 words
A METHOD OF IMPROVING THE GRADE OF BY-PRODUCT GYPSUM OBTAINED BY A WET PROCESS FOR MANUFACTURING PHOSPHORIC ACID AND CONTAINING FREE PHOSPHORIC ACID, WHICH COMPRISES THE STEPS OF FORMING A MIXTURE OF SAID BY-PRODUCT GYPSUM, AT LEAST ONE ADDITIVE SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF CALCIUM OXIDE, CALCIUM HYDROXIDE, CALCIUM CARBONATE, MAGNESIUM HYDROXIDE, MAGNESIUM CARBONATE, POWDER PRODUCED FROM PORTLAND CEMENT CLINKER, PORTLAND CEMENT, FLUE DUST PRODUCED FROM CEMENT KILN OPERATION, PULVERIZED SLAG PRODUCED FROM BLAST URNACE OPERATION, IRON HYDROXIDE, IRON OXIDE, ALUMINUM HYDROXIDE AND ALUMINUM OXIDE IN THE AMOUNT OF FROM 2 TO 6 TIMES THE AMOUNT THEORETICALLY REQUIRED TO NEUTRALIZE AND CONVERT THE TOTAL PHOSPHORIC ACID CONTAINED IN THE BY-PRODUCT GYPSUM INTO INERT PHOSPHATES, AND AT LEAST ONE BASIC SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF CAUSTIC ALKALI, AMMONIA AND SODIUM CARBONATE, SUBJECTING SAID MIXTURE TO HEATING WITH STEAM UNDER PRESSURE AT A TEMPERATURE OF FROM 120 TO 200*C., THEREBY TO FORM ONE SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF HALF-HYDRATED GYPSUM, ANHYDROUS GYPSUM AND MIXTURES THEREOF, AND SUBJECTING SAID SUBSTANCE THUS PRODUCED TO HYDRATION IN THE PRESENCE OF WATER THERBY TO FORM DIHYDRATED GYPSUM CONTAINING SAID AT LEAST ONE ADDITIVE SUBSTANCE.
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) | 1967-12-01 | 1968-06-01 | 1968-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1971-12-01 | 1972-06-01 | 1972-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1975-12-01 | 1976-06-01 | 1976-12-01 | $7700.00 | Window Closed / Lapsed |