US3868246A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pellet production process
Assignee: Dravo Corp
•
Filing: 1973-10-05
•
Granted: 1975-02-25
•
Expires: 1993-10-05
Abstract
Abstract A method is detailed in which stronger pellets or oxidic iron ores are produced, which are less susceptible to abrasion and breakage. In the present process, only a predetermined portion of the green pellet charge to be treated is initially disposed on a traveling grate, with this initial charge being dried. Thereafter, the remaining portion of the total of green pellets charge is added to the dried charge portion upon the traveling grate, and the total charge is then dried and calcined to produce the resultant stronger particle pellets.
Inventors
- 👤 Karl Heinz Boss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:04
CPC Classifications
F; F26; F26B; F26B17/00; F26B17/02; F26B17/04; F26B1/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
149 words
IN THE METHOD OF HEAT INDURATING GREEN PELLETS COMPRISING THE STEPS OF DEPOSITING GREEN PELLETS ON A TRAVELLING GRATE AND THEREAFTER DRYING, CALCINING AND COOLING SAID PELLETS, AN IMPROVED DRYING METHOD COMPRISING: A. DEPOSITING A PREDETERMINED PORTION OF A TOTAL CHARGE OF GREEN PELLETS ON THE RECEIVING END OF A TRAVELING GRATE, B. MOVING SAID PELLETS THROUGH A FIRST DOWNDRAFT DRYING ZONE WHEREIN HEATED GASES ARE PASSED DOWNWARDLY THROUGH THE PELLETS, SAID HEATED GASES BEING AT A SUFFICIENT TEMPERATURE TO DRIVE-OFF ENTRAINED MOISTURE FROM SAID PELLETS BUT AT A TEMPERATURE INSUFFICIENT TO CALCINE SAID PELLETS, C. DEPOSITING ADDITIONAL GREEN PELLETS ON TOP OF THE FIRSTDRIED PELLETS, AND D. SUBJECTING THE BED TO A DOWNDRAFT FLOW OF HEATED GASES AT THE SAID TEMPERATURE BEFORE THE FIRST-DRIED PELLETS HAVE COOLED TO THE LEVEL OF THE DEW POINT OF THE MOISTURE-LADEN GASES THAT HAVE CONTACTED THE PELLETS LAST DEPOSITED ON THE BED.
Claim 2
Dependent Claim
149 words
IN THE METHOD OF HEAT INDURATING GREEN PELLETS COMPRISING THE STEPS OF DEPOSITING GREEN PELLETS ON A TRAVELLING GRATE AND THEREAFTER DRYING, CALCINING AND COOLING SAID PELLETS, AN IMPROVED DRYING METHOD COMPRISING: A. DEPOSITING A PREDETERMINED PORTION OF A TOTAL CHARGE OF GREEN PELLETS ON THE RECEIVING END OF A TRAVELING GRATE, B. MOVING SAID PELLETS THROUGH A FIRST DOWNDRAFT DRYING ZONE WHEREIN HEATED GASES ARE PASSED DOWNWARDLY THROUGH THE PELLETS, SAID HEATED GASES BEING AT A SUFFICIENT TEMPERATURE TO DRIVE-OFF ENTRAINED MOISTURE FROM SAID PELLETS BUT AT A TEMPERATURE INSUFFICIENT TO CALCINE SAID PELLETS, C. DEPOSITING ADDITIONAL GREEN PELLETS ON TOP OF THE FIRSTDRIED PELLETS, AND D. SUBJECTING THE BED TO A DOWNDRAFT FLOW OF HEATED GASES AT THE SAID TEMPERATURE BEFORE THE FIRST-DRIED PELLETS HAVE COOLED TO THE LEVEL OF THE DEW POINT OF THE MOISTURE-LADEN GASES THAT HAVE CONTACTED THE PELLETS LAST DEPOSITED ON THE BED.
Claim 3
Dependent Claim
23 words
The improvement of claim 1 wherein said additional green pellets comprise the remainder of the total charge following depositing of the predetermined portion.
Claim 4
Dependent Claim
21 words
The improvement of claim 1 wherein the predetermined portion of green pellets comprises from one-half to two-thirds of the total charge.
Claim 5
Dependent Claim
19 words
The improvement of claim 1 wherein the temperature of the heated gases are from about 200*C. to about 350*C.
Claim 6
Dependent Claim
23 words
The improvement of claim 1 wherein the predetermined portion of green pellets is dried for a period from about 2 to 4 minutes.
Claim 7
Dependent Claim
29 words
The improvement of claim 1 wherein the heated gases are derived from the second of two cooling zones through which the traveling grate passes following calcining of the pellets.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-24 | 1978-08-26 | 1979-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-24 | 1982-08-26 | 1983-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-24 | 1986-08-26 | 1987-02-25 | $7700.00 | Window Closed / Lapsed |