# US 4,394,167 A · Method of carbothermically producing aluminum

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- Number: US 4,394,167 A
- Document ID: US4394167A
- Status: Granted
- Kind: A
- Application number: 06/241,053
- Filed: 1981-03-06
- Granted: 1983-07-19
- Earliest claimed: 1980-04-22
- Assignees: Mitsui Aluminum Co., Ltd.
- Inventors: Kenshi Kuwahara
- Web page: https://patentgrep.com/patent/US4394167A

## CPC

- C22B 21/02: with reducing {(C22B21/04 takes precedence)}
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS

## Abstract

A method of producing an aluminum metal from alumina, silica and iron oxide bearing materials by mixing the coal and bringing the mixtures to the temperature in the range of 600.degree. to 900.degree. C. in order to make the alumina bearing coked briquettes. Then, the coked briquettes are brought to the temperature in the range of 2,000.degree. to 2,100.degree. C. to produce aluminum, silicon and iron containing alloys. The alloys are scrubbed by molten lead spray directly after the alloys formation, and are converted to lead-aluminum alloy. An aluminum is separated from lead by liquation and purified by fractional distillation.

## Claims

### Claim 1

A method of carbothermically producing an aluminum metal from alumina, silica and iron-oxide bearing materials, which comprises;
(a) providing briquettes of a mix of said materials and a carbonaceous material which contains a sufficient amount of carbon to reduce the oxides in the material and coking said briquettes at a temperature of 600.degree. to 900.degree. C. by direct contact with non-oxidizing gas, to form coked briquettes,
(b) heating the coked briquettes to a temperature of 2,000.degree. to 2,100.degree. C. with gas for combustion to form an aluminum-silicon-iron alloy,
(c) scrubbing the resulting alloy in the nascent state with a molten lead splash to preferentially absorb the aluminum in the alloy into the molten lead,
(d) separating the silicon and iron of the alloy from the aluminum-absorbed molten lead,
(e) cooling the aluminum-absorbed molten lead to cause it to separate into liquid layers of aluminum and lead, respectively, and
(f) subjecting the aluminum layer to distillation to distill off lead present and recover aluminum metal in substantially pure form.

### Claim 2 (depends on 1)

The method of claim 1 wherein the coking step (a) is effected in a coking furnace.

### Claim 3 (depends on 2)

The method of claim 2 wherein the heating step (b) is effected in a blast furnace.

### Claim 4 (depends on 3)

The method of claim 3 wherein the scrubbing step (c) is effected by splashing the molten lead under the tuyere level in the bottom of the blast furnace.

### Claim 5 (depends on 4)

The method of claim 4 wherein the cooling step (d) is effected in a liquation pot located adjacent to the blast furnace.

### Claim 6 (depends on 5)

The method of claim 5 wherein the distillation step (e) is effected in a separate pot located adjacent to the liquation pot.

### Claim 7 (depends on 6)

The method of claim 6 wherein the distillation is carried out under reduced pressure.

### Claim 8 (depends on 1, 2, 3, 4, 5, 6, 7)

The method of any one of claims 1-7 wherein the carbonaceous material is a coking coal.

### Claim 9 (depends on 8)

The method of claim 8 wherein the non-oxidizing gas contains less than 1% by weight of oxygen.

### Claim 10 (depends on 8)

The method of claim 8 wherein the coking is carried out for 20-50 minutes.

### Claim 11 (depends on 8)

The method of claim 8 wherein said mix contains carbon in an amount of 35-50 wt.% in the form of coking coal.

### Claim 12 (depends on 8)

The method of claim 8 wherein said mix contains silica and alumina in a molecular weight ratio in the range of 1:1 to 2:1.

### Claim 13 (depends on 8)

The method of claim 8 wherein the alumina bearing material is selected from the group consisting of clay, kaolinite, agalmatorite, aluminous shale and bauxite.