# US 4,395,281 A · Treating molten pig iron in a torpedo

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- Number: US 4,395,281 A
- Document ID: US4395281A
- Status: Granted
- Kind: A
- Application number: 06/333,335
- Filed: 1981-12-22
- Granted: 1983-07-26
- Earliest claimed: 1980-12-23
- Assignees: Asea AB
- Inventors: Goran Grimfjard
- Web page: https://patentgrep.com/patent/US4395281A

## CPC

- H05B 6/34: Arrangements for circulation of melts
- B01F 33/451: wherein the mixture is directly exposed to an electromagnetic field without use of a stirrer, e.g. for material comprising ferromagnetic particles or for molten metal
- C21C 1/02: Dephosphorising or desulfurising
- B01F 2101/45: Mixing in metallurgical processes of ferrous or non-ferrous materials
- H05B 2213/02: Stirring of melted material in melting furnaces
- Y02P 10/25: Process efficiency
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- B01F: MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING (mixing paints B44D3/06)
- C21C: PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Pig iron is tapped from a blast furnace into a torpedo in which the iron has a treating agent introduced to it while the iron is electromagnetically stirred lengthwise in the torpedo to uniformly distribute the agent throughout the iron while reducing the tendency for skulling in the torpedo.

## Claims

### Claim 1

A method for treating molten pig iron containing sulfur, in the torpedo of a torpedo car, the torpedo comprising a horizontal generally cylindrical body having tapered ends extending horizontally from both ends thereof and the body having a substantially central opening in its top and through which a lance is inserted into the iron and a desulfurizing agent is blown through the lance into the iron by compressed gas for reaction with the sulfur in the iron; wherein the improvement comprising providing the torpedo with at least one longitudinally extending magnetically permeable window and positioning at least one straight electromagnetic stirrer longitudinally on the outside of the window so as to project a traveling multi-phase AC field into the iron causing stirring of the iron longitudinally in the torpedo.

### Claim 2 (depends on 1)

The method of claim 1, in which the agent is introduced to a substantially fixed zone in the pig iron.

### Claim 3 (depends on 2)

The method of claim 2 in which the agent is in the form of solid particles and the stirring is adequately intense to spread the particles throughout the pig iron and increase the uniformity of the agent's reaction with the sulphur.

### Claim 4 (depends on 3)

The method of claim 3 in which the stirring intensity is adequate to reduce the formation of a skull in the torpedo's inside.

### Claim 5 (depends on 4)

The method of claim 4 in which the torpedo is inverted to discharge the pig iron after the treatment and the stirring is directed so as to at least retard the simultaneous discharge of slag with the pig iron.

### Claim 6

A torpedo car having a horizontal longitudinally extended torpedo adapted to contain pig iron for its treatment, the torpedo having at least one longitudinally extending wall portion which is non-magnetic and at least one electromagnetic stirrer positioned opposite to said portion so as to stir the pig iron when it is in the torpedo, the stirrer being a straight stirrer and positioned longitudinally with respect to the torpedo.

### Claim 7 (depends on 6)

The torpedo of claim 6 in which the torpedo and stirrer are movable relative to each other and the torpedo's non-magnetic portion is extensive enough to embrace the range of the movement.