# US 6,136,059 A · Process for reducing the electric steelworks dusts and facility for implementing it

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- Number: US 6,136,059 A
- Document ID: US6136059A
- Status: Granted
- Kind: A
- Application number: 08/961,989
- Filed: 1997-10-31
- Granted: 2000-10-24
- Earliest claimed: 1996-11-01
- Assignees: Ecochem Aktiengesellschaft
- Inventors: Gianni Zoppi
- Web page: https://patentgrep.com/patent/US6136059A

## CPC

- C22B 7/02: Working-up flue dust
- C21C 5/5241: {in an inductively heated furnace}
- Y02P 10/20: Recycling
- Y02P 10/25: Process efficiency
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- 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

A process for processing electric steelworks dusts containing oxidized high-iron, zinc-bearing materials in order to recover iron and zinc from [them] said dusts. The process includes the steps of: feeding the dusts to an induction furnace partially filled with a charge of metal or alloy to be smelted, wherein the charge is present as a molten bath that is made turbulent by induced currents; contacting the dusts with a surface of the turbulent molten bath inside the furnace; and reducing zinc and iron oxides contained in the dusts inside the furnace, while oxidizing zinc and carbon monoxide rising from the bath.

## Claims

### Claim 1

A method for processing electric steelworks dusts containing oxidized high-iron, zinc-bearing materials to reduce iron and zinc from said dusts, comprising:
feeding said dusts to a reduction section of a coreless induction furnace, wherein said reduction section is partially filled with a charge of metal or alloy in the form of a molten bath made turbulent by induced currents; wherein said dusts contact a surface of said turbulent molten bath inside said furnace to reduce zinc and iron oxides contained in said dusts;
forming vapors containing zinc from said bath that rise above said bath;
oxidizing the zinc in said vapors.

### Claim 2 (depends on 1)

Process according to claim 1, wherein said charge comprises cast iron and wherein said zinc oxide contained in said dusts reacts with carbon contained in said cast iron according to the following reaction:
ZnO+C.sub.(Fe) .fwdarw.Zn+CO (1).

### Claim 3 (depends on 2)

Process according to claim 2, wherein said metal zinc produced in reaction (1) vaporizes and reacts with iron oxide contained in said dusts according to the reaction:
FeO+Zn.fwdarw.Fe+ZnO (2).

### Claim 4 (depends on 2)

The process of claim 2, further comprising mixing coal, in granular form, with said dust, to form a mixture; and
contacting said molten cast iron with said mixture, thereby maintaining constant the carbon level of said molten cast iron.

### Claim 5 (depends on 1)

Process according to claim 1, wherein said dusts are mixed with coal.

### Claim 6 (depends on 5)

The process of claim 5, wherein said coal is in a granular form.

### Claim 7 (depends on 1)

Process according to claim 1, wherein said dusts are fed to said furnace after being dried and pre-heated.

### Claim 8 (depends on 1)

Process according to claim 1, wherein said iron and said zinc are recovered as cast iron and zinc oxide, respectively.

### Claim 9 (depends on 1)

The process of claim 1, wherein said surface of said bath is a free surface.

### Claim 10 (depends on 1)

The method of claim 1, wherein said vapors additionally contain carbon monoxide.

### Claim 11

A method for processing electric steelworks dusts containing oxidized high-iron, zinc-bearing materials to reduce iron and zinc from said dusts, comprising:
feeding said dusts to a reduction section of a coreless induction furnace, wherein said reduction section is partially filled with a charge of metal or alloy in the form of a molten bath made turbulent by induced currents; wherein said dusts contact a surface of said turbulent molten bath inside said furnace to reduce zinc and iron oxides contained in said dusts;
forming vapors containing zinc from said bath that rise above said bath;
oxidizing the zinc in said vapors in an oxidation zone of the furnace, wherein the zinc in said vapors is oxidized by iron oxides.