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US4722750A
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Agglomerated ores and a producing method therefor
Assignee: JFE Steel Corp
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Filing: 1985-04-12
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Granted: 1988-02-02
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Expires: 2005-04-12
Abstract
Abstract PCT No. PCT/JP85/00192 Sec. 371 Date Aug. 15, 1985 Sec. 102(e) Date Aug. 15, 1985 PCT Filed Apr. 12, 1985 PCT Pub. No. WO86/02668 PCT Pub. Date May 9, 1986.Mini-pellets made of raw materials of fine powder iron ores are indurated, and effected with diffusion bond. A plurality of said treated mini-pellets are combined with calcium ferrites at the surface layers thereof. Thus, agglomerated ores are produced, wherein main grain sizes of said fine powder iron ores are not more than 5 mm, and are subjected to a primary pelletization with flux, and solid fuels are coated in a secondary pelletization to produce the mini-pellets of 3 to 9 mm diameter, and the produced mini-pellets are undertaken with induration in a travelling grate typed sintering furnace. Depending upon the present agglomerated ores and the producing method therefor, the raw materials may be selected from a wide range of grain sizes, and a blow faculty is enough to be small, and producing yield of the agglomerated ores may be increased, having improved qualities of high RI and low RDI.
Inventors
- 👤 Hiroshi Saito
- 👤 Noboru Sakamoto
- 👤 Hiroshi Fukuya
- 👤 Yoshihito Iwata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 03:16
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/028; H10D30/0291; C; C22; C22B; C22B1/00; C22B1/14; C22B1/16; C22B1/24; C22B1/2406; C22B1/242; C22B1/243
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
277 words
A method of producing agglomerated iron ores, comprising the steps of adding a flux containing lime substance to iron ore comprising more than 80% hematite and less than 20% magnetite, said iron ore having a grain size 5 mm or less consisting of iron ore and flux; primarily pelletizing the mixture of flux and iron ore to form first pellets; adding flux containing lime substance and solid fuel selected from the group consisting of grain coke, grain cha, dust coal, and grain charcoal, having more than 50% of grain size of -125 μm, and in an amount of 2.5 to 3.5 weight percent based on the amount of iron ore to the first pellets obtained from the primary pelletizing; secondarily pelletizing the first pellets to coat the first pellets with said lime substance and solid fuel and to form mini-pellets from the first pellets having grain size ranging from 3 to 9 mm and having their surfaces coated with said solid fuel to effect diffusion bonding; processing the mini-pellets on a travelling grate sintering furnace by subjecting the mini-pellets first to drying, then subsequently to firing at a temperature of a maximum of 1270° C. for about 1 minute, then thereafter indurating and cooling, and then finally to crushing and filtering, thereby to produce agglomerated iron ores of said mini-pellets having a diameter of more than 3 mm, wherein the total amount of flux is sufficient to produce basicicity of the agglomerated ore to be in the range of 1.8 to 2.0 and wherein more than 50% of the total flux added in both the primary and secondary pelletizing steps is added in the primary pelletizing step.
Claim 2
Independent Claim
277 words
A method of producing agglomerated iron ores, comprising the steps of adding a flux containing lime substance to iron ore comprising more than 80% hematite and less than 20% magnetite, said iron ore having a grain size 5 mm or less consisting of iron ore and flux; primarily pelletizing the mixture of flux and iron ore to form first pellets; adding flux containing lime substance and solid fuel selected from the group consisting of grain coke, grain cha, dust coal, and grain charcoal, having more than 50% of grain size of -125 μm, and in an amount of 2.5 to 3.5 weight percent based on the amount of iron ore to the first pellets obtained from the primary pelletizing; secondarily pelletizing the first pellets to coat the first pellets with said lime substance and solid fuel and to form mini-pellets from the first pellets having grain size ranging from 3 to 9 mm and having their surfaces coated with said solid fuel to effect diffusion bonding; processing the mini-pellets on a travelling grate sintering furnace by subjecting the mini-pellets first to drying, then subsequently to firing at a temperature of a maximum of 1270° C. for about 1 minute, then thereafter indurating and cooling, and then finally to crushing and filtering, thereby to produce agglomerated iron ores of said mini-pellets having a diameter of more than 3 mm, wherein the total amount of flux is sufficient to produce basicicity of the agglomerated ore to be in the range of 1.8 to 2.0 and wherein more than 50% of the total flux added in both the primary and secondary pelletizing steps is added in the primary pelletizing step.
Claim 3
Dependent Claim
20 words
The method of claim 1, wherein the solid fuel is added in an amount of 2.7 to 3.0% by weight.
Claim 4
Dependent Claim
34 words
The method of claim 1, wherein said mini-pellets are charged as a layer into a grate part of said travelling grate sintering furnace, said layer being of a thickness of 300 to 500 mm.
References Cited (Backward Citations)
US3868246A
Cited
US4082540A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-01 | 1991-08-03 | 1992-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-01 | 1995-08-03 | 1996-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-01 | 1999-08-03 | 2000-02-02 | $7700.00 | Window Closed / Lapsed |