US3975187A — Treatment of carbothermically produced aluminum

Claim 1

Independent Claim 127 words

A process for decreasing aluminum carbide contamination of aluminum produced by carbothermic processes, said process comprising: A. preparing said aluminum contaminated with up to 20 weight percent of aluminum carbide as a melt at an initial temperature sufficiently high to keep said melt in a fluid state; B. blowing said melt with a gas which comprises oxygen, air, carbon dioxide, steam, carbon monoxide, or a mixture of chlorine, nitrogen, and carbon monoxide, wherein chlorine is present in an amount no greater than about 20 weight percent, or mixtures of these gases for a sufficient period of time to prevent the formation of an aluminum-aluminum carbide matrix, whereby said aluminum carbide becomes readily separable from said aluminum; C. separating said aluminum carbide from said aluminum in said melt.

Claim 2

Dependent Claim 127 words

A process for decreasing aluminum carbide contamination of aluminum produced by carbothermic processes, said process comprising: A. preparing said aluminum contaminated with up to 20 weight percent of aluminum carbide as a melt at an initial temperature sufficiently high to keep said melt in a fluid state; B. blowing said melt with a gas which comprises oxygen, air, carbon dioxide, steam, carbon monoxide, or a mixture of chlorine, nitrogen, and carbon monoxide, wherein chlorine is present in an amount no greater than about 20 weight percent, or mixtures of these gases for a sufficient period of time to prevent the formation of an aluminum-aluminum carbide matrix, whereby said aluminum carbide becomes readily separable from said aluminum; C. separating said aluminum carbide from said aluminum in said melt.

Claim 3

Dependent Claim 14 words

The process of claim 1 wherein said gas consists essentially of oxygen or air.

Claim 4

Dependent Claim 12 words

The process of claim 1 wherein said gas consists essentially of steam.

Claim 5

Dependent Claim 13 words

The process of claim 1 wherein said gas consists essentially of carbon dioxide.

Claim 6

Dependent Claim 13 words

The process of claim 1 wherein said gas consists essentially of carbon monoxide.

Claim 7

Dependent Claim 31 words

The process of claim 1 wherein said gas is a mixture of chlorine, nitrogen, and carbon monoxide, wherein chlorine is present in an amount no greater than about 20 weight percent.

Claim 8

Dependent Claim 20 words

The process of claim 1 wherein said initial temperature varies directly with the initial amount of said aluminum carbide contamination.

Claim 9

Dependent Claim 18 words

The process of claim 7 wherein said initial temperature is about 1500°C when said initial amount is 2%.

Claim 10

Dependent Claim 34 words

The process of claim 1 wherein said blowing is at a flow rate for said reactive gas of from about 0.02 to about 5 liters per minute for each 100 grams of said melt.

Claim 11

Dependent Claim 24 words

The process of claim 9 wherein said flow rate is from 0.04 to 0.06 liters per minute for each 100 grams of said melt.

Claim 12

Dependent Claim 22 words

The process of claim 1 wherein said separated aluminum carbide is recycled directly back to a reduction furnace without additional chemical treatment.

Claim 13

Dependent Claim 20 words

The process of claim 1 wherein said contamination is no more than about 5 weight percent of said aluminum carbide.

Claim 14

Dependent Claim 47 words

The process of claim 1 wherein said preparing of said melt comprises pouring said aluminum contaminated with said aluminum carbide into a receptacle which is provided with inlets through which said gas is passed under pressure so that said gas passes through the body of said melt.

Claim 15

Dependent Claim 105 words

In a carbothermic process for producing aluminum in an electric furnace by reacting an aluminum-oxygen compound with a carbon-containing reductant to produce a mixture of aluminum and aluminum carbide which solidifies as an aluminum-aluminum carbide matrix while cooling, the improvement comprising: A. while said mixture is a melt in a fluid state at an uppermost temperature determined by an initial amount that is no greater than 5% by weight of said aluminum carbide admixed with said aluminum, sufficiently removing said aluminum carbide from said mixture and reducing said initial amount so that said aluminum remaining therein is substantially pure, said removing comprising the steps of:

Claim 16

Dependent Claim 105 words

In a carbothermic process for producing aluminum in an electric furnace by reacting an aluminum-oxygen compound with a carbon-containing reductant to produce a mixture of aluminum and aluminum carbide which solidifies as an aluminum-aluminum carbide matrix while cooling, the improvement comprising: A. while said mixture is a melt in a fluid state at an uppermost temperature determined by an initial amount that is no greater than 5% by weight of said aluminum carbide admixed with said aluminum, sufficiently removing said aluminum carbide from said mixture and reducing said initial amount so that said aluminum remaining therein is substantially pure, said removing comprising the steps of:

Claim 17

Dependent Claim 91 words

passing a gas which consists essentially of oxygen, air, steam, carbon monoxide, carbon dioxide, or a mixture of chlorine, nitrogen, and carbon monoxide, wherein chlorine is present in an amount no greater than about 20 weight percent, for a sufficient period of time to prevent the formation of an aluminum-aluminum carbide matrix, whereby said aluminum carbide separates to the surface of said melt, and 2. skimming said separated aluminum carbide from the said surface, and B. recycling said skimmed aluminum carbide directly back to said electric furnace without additional chemical treatment.

Claim 18

Dependent Claim 91 words

passing a gas which consists essentially of oxygen, air, steam, carbon monoxide, carbon dioxide, or a mixture of chlorine, nitrogen, and carbon monoxide, wherein chlorine is present in an amount no greater than about 20 weight percent, for a sufficient period of time to prevent the formation of an aluminum-aluminum carbide matrix, whereby said aluminum carbide separates to the surface of said melt, and 2. skimming said separated aluminum carbide from the said surface, and B. recycling said skimmed aluminum carbide directly back to said electric furnace without additional chemical treatment.

Claim 19

Dependent Claim 14 words

The process of claim 14 wherein said gas consists essentially of air or oxygen.

Claim 20

Dependent Claim 12 words

The process of claim 14 wherein said gas consists essentially of steam.

Claim 21

Dependent Claim 13 words

The process of claim 14 wherein said gas consists essentially of carbon dioxide.

Claim 22

Dependent Claim 13 words

The process of claim 14 wherein said gas consists essentially of carbon monoxide.

Claim 23

Dependent Claim 18 words

The process of claim 1 wherein said gas consists essentially of a mixture of carbon monoxide and chlorine.

Claim 24

Dependent Claim 18 words

The process of claim 14 wherein said gas consists essentially of a mixture of carbon monoxide and chlorine.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1979-08-17	1980-02-16	1980-08-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1983-08-17	1984-02-16	1984-08-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1987-08-17	1988-02-16	1988-08-17	$7700.00	Window Closed / Lapsed

Treatment of carbothermically produced aluminum

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