# US 8,771,400 B2 · Method for manufacturing molten iron

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- Number: US 8,771,400 B2
- Document ID: US8771400B2
- Status: Granted
- Kind: B2
- Application number: 13/320,325
- Filed: 2010-05-14
- Published: 2012-03-15
- Granted: 2014-07-08
- Earliest claimed: 2009-05-15
- Assignees: ISTC Co., Ltd.
- Applicants: Teruyoshi Hiraoka
- Inventors: Teruyoshi Hiraoka
- Web page: https://patentgrep.com/patent/US8771400B2

## CPC

- C21C 5/32: Blowing from above (C21C5/35 takes precedence)
- C21C: PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

## Abstract

An object of the present invention is to provide a method for producing molten iron, the method being capable of minimizing the generation of converter dust and increasing the thermal degree of freedom in the converter process. In addition, the present invention provides a method for improving a converter operation method in the production of steels. The present invention relates to a method for producing molten iron including the steps of: 1) supplying carbon-containing molten pig iron to a converter, 2) continuously supplying iron oxide into the converter, and 3) blowing a mixed gas comprising a fuel gas and a combustion-supporting gas at a speed equal to or faster than the speed of sound to the molten pig iron to cause a combustion reaction, thereby heating the molten pig iron by heat of the combustion reaction.

## Claims

### Claim 1

A method for producing molten iron comprising the steps of:
1) supplying carbon-containing molten pig iron to a converter,
2) continuously supplying iron oxide into the converter to decarburize the pig iron, and
3) blowing a mixed gas comprising a fuel gas and a combustion-supporting gas, in an amount corresponding to the amount needed to combust the fuel gas, at a speed equal to or faster than the speed of sound to the molten pig iron to cause a combustion reaction, thereby heating the molten pig iron by heat of the combustion reaction.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the amount of iron oxide added is equal to or greater than the corresponding amount of carbon contained in the molten pig iron supplied in step 1) and the amount of oxygen required for reducing the amount of other chemical components bindable to oxygen to a desirable level.

### Claim 3 (depends on 2)

The method according to claim 2 comprising: mixing a fuel gas and a combustion-supporting gas in a metal tube, the outside of the metal tube being water-cooled, and performing ejection at a speed equal to or faster than the speed of sound from a de Laval nozzle provided at an end of the water-cooled metal tube so that blowing is performed from above molten pig iron and iron oxide.

### Claim 4 (depends on 2)

The method according to claim 2, wherein a mixed gas comprising a fuel gas and a combustion-supporting gas is blown into molten pig iron from the bottom of a converter to cause a combustion reaction in the molten pig iron, thereby heating the molten pig iron.

### Claim 5 (depends on 3)

The method according to claim 3, wherein a mixed gas comprising a fuel gas and a combustion-supporting gas is blown into molten pig iron from the bottom of a converter to cause a combustion reaction in the molten pig iron, thereby heating the molten pig iron.

### Claim 6 (depends on 1)

The method according to claim 1 comprising: mixing a fuel gas and a combustion-supporting gas in a metal tube, the outside of the metal tube being water-cooled, and performing ejection at a speed equal to or faster than the speed of sound from a de Laval nozzle provided at an end of the water-cooled metal tube so that blowing is performed from above molten pig iron and iron oxide.

### Claim 7 (depends on 6)

The method according to claim 6, wherein a mixed gas comprising a fuel gas and a combustion-supporting gas is blown into molten pig iron from the bottom of a converter to cause a combustion reaction in the molten pig iron, thereby heating the molten pig iron.

### Claim 8 (depends on 1)

The method according to claim 1, wherein a mixed gas comprising a fuel gas and a combustion-supporting gas is blown into molten pig iron from the bottom of a converter to cause a combustion reaction in the molten pig iron, thereby heating the molten pig iron.