US4054443A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing iron powder
Assignee: Midrex Corp
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Filing: 1975-12-22
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Granted: 1977-10-18
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Expires: 1995-12-22
Abstract
Abstract A method for preparing iron powder for powder metallurgy and other applications from particulate iron oxide by reducing the particle size of at least part of the particulate feed material chemically reducing the feed material to increase the percentage of metallization by contact with a gaseous reductant in a shaft furnace at high temperatures, and removing the reduced iron powder product from the furnace. Preferably the product is screened and oversized material is returned to the furnace for additional reduction. An alternative method contemplates additional steps of grinding, and further decrepitation to reduce the particle size of the larger particle fractions.
Inventors
- 👤 Charles M. Jaco, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:51
CPC Classifications
C; C21; C21B; C21B13/00; C21B13/0046; B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/20; B22F9/22; C21B13/02; C21B13/14; C21B13/146; Y; Y02; Y02P; Y02P10/00; Y02P10/10; Y02P10/134; Y02P10/20
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
151 words
A method for preparing iron powder from feed material selected from the group comprising particulate iron ore, lump iron ore iron oxide fines, pellets, nodules, balls, partially reduced iron and mixtures thereof, said method comprising: a. selecting ores which are subject to decrepitation to be included in the feed material; b. reducing the particle size of said feed materials; c. establishing continuous a gravitational flow of said feed material through a generally vertical direct reduction shaft furnace; d. chemically reducing said feed material by counter-current flow of a gaseous reductant through said feed material in said direct reduction furnace; e. controlling the reducing gas temperature between about 1550° and 2050° F to promote degradation of the feed material in said furnace; f. controlling the pressure in the reduction furnace between 3 and 15 pounds per square inch to promote degradation; and g. removing the reduced iron powder product from the furnace.
Claim 2
Independent Claim
151 words
A method for preparing iron powder from feed material selected from the group comprising particulate iron ore, lump iron ore iron oxide fines, pellets, nodules, balls, partially reduced iron and mixtures thereof, said method comprising: a. selecting ores which are subject to decrepitation to be included in the feed material; b. reducing the particle size of said feed materials; c. establishing continuous a gravitational flow of said feed material through a generally vertical direct reduction shaft furnace; d. chemically reducing said feed material by counter-current flow of a gaseous reductant through said feed material in said direct reduction furnace; e. controlling the reducing gas temperature between about 1550° and 2050° F to promote degradation of the feed material in said furnace; f. controlling the pressure in the reduction furnace between 3 and 15 pounds per square inch to promote degradation; and g. removing the reduced iron powder product from the furnace.
Claim 3
Dependent Claim
23 words
A method according to claim 1 wherein step (b) comprises heating said feed materials to at least about 700° F to promote decrepitation.
Claim 4
Dependent Claim
28 words
A method according to claim 2 in which said feed material is heated to at least 700° F prior to introducing said feed material to said reduction furnace.
Claim 5
Dependent Claim
16 words
A method according to claim 1 further comprising placing the reduced iron powder in sealed containers.
Claim 6
Dependent Claim
17 words
A method according to claim 1 further comprising mechanically degrading the material exiting the direct reduction furnace.
Claim 7
Dependent Claim
18 words
A method according to claim 1 further comprising passing said reduced iron powder through a second reducing stage.
Claim 8
Dependent Claim
25 words
A method according to claim 1 wherein the particle size of said feed material is reduced by decrepitation during simultaneous reduction in said reduction furance.
Claim 9
Dependent Claim
22 words
A method according to claim 1 further comprising controlling the moisture content, size, and quality of the feed material to promote degradation.
Claim 10
Dependent Claim
18 words
A method according to claim 1 wherein the particle size of said feed material is reduced by crushing.
Claim 11
Dependent Claim
19 words
A method according to claim 1 wherein said reducing gas temperature is maintained between about 1700° and 2000° F.
Claim 12
Dependent Claim
20 words
A method according to claim 1 further comprising screening said product and recycling oversized material to said furnace as feed.
Claim 13
Dependent Claim
19 words
A method according to claim 1 further comprising introducing finely divided material to the feed material to promote degradation.
Claim 14
Dependent Claim
18 words
A method according to claim 12 from 5 to 50 percent of the feed material is finely divided.
Claim 15
Dependent Claim
17 words
A method according to claim 1 further comprising recycling undecrepitated product to the furnace as feed material.
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) | 1980-10-17 | 1981-04-18 | 1981-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-17 | 1985-04-18 | 1985-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-17 | 1989-04-18 | 1989-10-18 | $7700.00 | Window Closed / Lapsed |