# US 7,744,810 B2 · Microwave iron-making furnace

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- Number: US 7,744,810 B2
- Document ID: US7744810B2
- Status: Granted
- Kind: B2
- Application number: 12/219,942
- Filed: 2008-07-30
- Published: 2009-02-12
- Granted: 2010-06-29
- Earliest claimed: 2007-08-01
- Assignees: Tokyo Institute of Technology; Inter-University Research Institute Corporation National Institutes of Natural Sciences
- Inventors: Kazuhiro Nagata; Motoyasu Sato
- Web page: https://patentgrep.com/patent/US7744810B2

## CPC

- F27B 5/04: adapted for treating the charge in vacuum or special atmosphere
- C21B 13/12: in electric furnaces
- C21C 5/52: Manufacture of steel in electric furnaces {(C21C5/005 takes precedence)}
- F27B 5/14: Arrangements of heating devices
- F27B 5/16: Arrangements of air or gas supply devices
- F27D 1/0006: {Linings or walls formed from bricks or layers with a particular composition or specific characteristics}
- F27D 99/0006: {Electric heating elements or system}
- F27D 2099/0028: {Microwave heating}
- Y02P 10/20: Recycling
- F27B: FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- C21B: MANUFACTURE OF IRON OR STEEL (preliminary treatment of ferrous ores or scrap C22B1/00)
- C21C: PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- F27D: DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A reactor has a casing composed of a magnesia-based refractory, and a bottom plate composed of an MgO-graphite mixed refractory is disposed on a bottom part of this casing. A graphite crucible is provided at a bottom of the reactor, and the graphite crucible and the reactor are joined together by a magnesia cylinder. Iron ore powder, coal powder, and other such raw materials supplied into the reactor are irradiated with microwaves from microwave oscillators and are heated. The iron ore is reduced, and the resulting molten pig iron flows out through a hole into a crucible, and then is poured out of the crucible through another hole into a ladle. It is thereby possible to manufacture molten pig iron with high energy efficiency, instead of using blast-furnace iron-making.

## Claims

### Claim 1

A microwave iron-making furnace, comprising:
a reactor having a casing and a blanket for covering a side, bottom, and top surface of the casing;
a microwave oscillator for irradiating an interior of the reactor with microwaves;
a raw material powder supply apparatus for supplying a raw material powder containing iron ore and a carbon source to the interior of said reactor; and
an extraction part for extracting molten iron from the reactor,
wherein said microwave oscillator directs, into the interior of the reactor, microwaves that have been imparted with directivity using a helical antenna,
wherein the raw material powder in the reactor is irradiated and heated by the microwaves from the microwave oscillator that have been imparted with directivity by the helical antenna,
wherein the iron ore is reduced using the carbon source, and
wherein the molten iron is obtained.

### Claim 2 (depends on 1)

The microwave iron-making furnace according to claim 1, wherein said extraction part comprises a hole opened in a bottom of said reactor, and a crucible comprising graphite for receiving molten pig iron that flows out through said hole is provided below said reactor.

### Claim 3 (depends on 2)

The microwave iron-making furnace according to claim 2, wherein a cylinder comprising a magnesia-based refractory is provided between said crucible and a bottom surface of said reactor, and a space enclosed by said reactor, said cylinder, and said crucible is formed below said reactor.

### Claim 4 (depends on 3)

The microwave iron-making furnace according to claim 3, wherein a nozzle is formed in a bottom surface of said crucible, and molten pig iron flowing out of said reactor into said crucible is poured from said nozzle into a ladle provided below the nozzle.