US4680096A
Expired / Lapsed
US
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Plasma smelting process for silicon
Assignee: Dow Silicones Corp
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Filing: 1985-12-26
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Granted: 1987-07-14
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Expires: 2005-12-26
Abstract
Abstract What is disclosed is a process for preparing silicon using a gas plasma as a heat source. The process comprises (a) generating a gas plasma in a reactor utilizing a transferred arc plasma configuration in which a minimum of gas is utilized to form a plasma; (b) feeding silicon dioxide and a solid reducing agent directly into the reactor and to the plasma; (c) passing the plasma gas, the silicon dioxide, and the solid reducing agent into a reaction zone of the reactor; (d) recovering molten silicon and the gaseous by-products.
Inventors
- 👤 Vishu D. Dosaj
- 👤 Alvin W. Rauchholz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:01
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/02; C01B33/021; C01B33/023; C01B33/025
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
90 words
A process for producing silicon using a gas plasma as the energy source, said process comprising (I) generating a gas plasma in a reactor utilizing a transferred arc configuration in which a minimum of gas is utilized to form the plasma; (II) feeding silicon dioxide and a solid reducing agent directly into the reactor and to the plasma; (III) passing the plasma gas, the silicon dioxide, and the solid reducing agent into a reaction zone of the reactor; (IV) recovering molten silicon and the gaseous by-products from the reaction zone.
Claim 2
Dependent Claim
90 words
A process for producing silicon using a gas plasma as the energy source, said process comprising (I) generating a gas plasma in a reactor utilizing a transferred arc configuration in which a minimum of gas is utilized to form the plasma; (II) feeding silicon dioxide and a solid reducing agent directly into the reactor and to the plasma; (III) passing the plasma gas, the silicon dioxide, and the solid reducing agent into a reaction zone of the reactor; (IV) recovering molten silicon and the gaseous by-products from the reaction zone.
Claim 3
Dependent Claim
39 words
A process according to claim 1, wherein the silicon dioxide and the solid reducing agent are fed, alternately, first as a mixture of silicon dioxide and the solid reducing agent and then silicon dioxide, the feeds being repeated alternately.
Claim 4
Dependent Claim
51 words
A process according to claim 2, wherein in the mixture of silicon dioxide and the solid reducing agent, the proportion of silicon dioxide and the solid reducing agent is controlled so that carbon is in a molar excess relative to silicon dioxide of up to 20 percent above the stoichiometric quantity.
Claim 5
Dependent Claim
54 words
A process according to claim 2, wherein in the mixture of silicon dioxide and the solid reducing agent, the proportion of silicon dioxide and the solid reducing agent is controlled so that carbon is in a molar excess relative to silicon dioxide in the range of 1 to 10 percent above the stoichiometric quantity.
Claim 6
Dependent Claim
33 words
A process according to claim 2, wherein the silicon dioxide feed is controlled so that the combined proportion of carbon and silicon dioxide is at essentially the stoichiometric quantity of the overall reaction.
Claim 7
Dependent Claim
21 words
A process according to claim 1, wherein the silicon dioxide and the solid reducing agent are fed as a combined mixture.
Claim 8
Dependent Claim
50 words
A process according to claim 6, wherein in the mixture of silicon dioxide and the solid reducing agent, the proportion of silicon dioxide and the solid reducing agent is controlled so that the combined proportion of carbon and silicon dioxide is at essentially the stoichiometric quantity of the overall reaction.
Claim 9
Dependent Claim
19 words
A process according to claim 1, wherein the reaction zone is partially filled with one or more solid reactants.
Claim 10
Dependent Claim
21 words
A process according to claim 8, wherein the solid reactant which partially fill the reaction zone is a solid reducing agent.
Claim 11
Dependent Claim
27 words
A process according to claim 8, wherein the solid reactants which partially fill the reaction zone are a mixture of silicon dioxide and a solid reducing agent.
Claim 12
Dependent Claim
35 words
A process according to claim 9, wherein the solid reducing agent which partially fills the reaction zone is the same as the solid reducing agent which is fed into the reactor and to the plasma.
Claim 13
Dependent Claim
34 words
A process according to claim 9, wherein the solid reducing agent which partially fills the reaction zone is different than the solid reducing agent which is fed into the reactor and to the plasma.
Claim 14
Dependent Claim
41 words
A process according to claim 10, wherein the solid reducing agent which is used in the mixture to partially fill the reaction zone is the same as the solid reducing agent which is fed into the reactor and to the plasma.
Claim 15
Dependent Claim
40 words
A process according to claim 10, wherein the solid reducing agent which is used in the mixture to partially fill the reaction zone is different than the solid reducing agent which is fed into the reactor and to the plasma.
Claim 16
Dependent Claim
39 words
A process according to claim 10, wherein the silicon dioxide which is used in the mixture to partially fill the reaction zone is the same as the silicon dioxide which is fed into the reactor and to the plasma.
Claim 17
Dependent Claim
38 words
A process according to claim 10, wherein the silicon dioxide which is used in the mixture to partially fill the reaction zone is different than the silicon dioxide which is fed into the reactor and to the plasma.
Claim 18
Dependent Claim
19 words
A process according to claim 1, wherein the silicon produced has a purity of at least 98 weight percent.
Claim 19
Dependent Claim
42 words
A process according to claim 1, wherein the flow of the plasma, the silicon dioxide, and the solid reducing agent is co-current in a downward direction, with the molten silicon and the gaseous by-products discharging at the bottom half of the reactor.
Claim 20
Dependent Claim
40 words
A process according to claim 1, wherein the flow of the plasma, the silicon dioxide, and the solid reducing agent is introduced to the bottom half of the reactor with the molten silicon discharging in the bottom of the reactor.
Claim 21
Dependent Claim
23 words
A process according to claim 1, wherein the reactor is maintained at a pressure in the range of atmospheric pressure to 6 atmospheres.
Claim 22
Dependent Claim
30 words
A process according to claim 1, wherein the gas used to form a plasma is a reducing gas selected from a group which comprises hydrogen, saturated hydrocarbons, and unsaturated hydrocarbons.
Claim 23
Dependent Claim
27 words
A process according to claim 1, wherein the gas used to form a plasma is an inert gas selected from a group which comprises argon and nitrogen.
Claim 24
Dependent Claim
25 words
A process according to claim 1, wherein the gas used to form a plasma is a mixture of a reducing gas and an inert gas.
Claim 25
Dependent Claim
12 words
A process according to claim 21, wherein the reducing gas is methane.
Claim 26
Dependent Claim
12 words
A process according to claim 22, wherein the inert gas is argon.
Claim 27
Dependent Claim
24 words
A process according to claim 23, wherein the mixture of a reducing gas and an inert gas is a mixture of hydrogen and argon.
Claim 28
Dependent Claim
24 words
A process according to claim 1, wherein the silicon dioxide feed is selected from a group which comprises quartz, fused silica, and fumed silica.
Claim 29
Dependent Claim
30 words
A process according to claim 1, wherein the solid reducing agent feed to the reactor is selected from a group which comprises carbon black, charcoal, coke, coal, and wood chips.
Claim 30
Dependent Claim
28 words
A process according to claim 2, wherein the silicon dioxide feed is in a form selected from a group which comprises powders, granules, lumps, pebbles, pellets, and briquettes.
Claim 31
Dependent Claim
42 words
A process according to claim 2, wherein the mixture of silicon dioxide and solid reducing agent which is fed into the reactor and to the plasma is in a form selected from a group which comprises powders, granules, lumps, pellets, and briquettes.
Claim 32
Dependent Claim
42 words
A process according to claim 6, wherein the mixture of silicon dioxide and solid reducing agent which is fed into the reactor and to the plasma is in a form selected from a group which comprises powders, granules, lumps, pellets, and briquettes.
Claim 33
Dependent Claim
33 words
A process according to claim 9, wherein the solid reducing agent which is used to partially fill the reactor is selected from a group which comprises carbon black, charcoal, coke, coal, and wood.
Claim 34
Dependent Claim
36 words
A process according to claim 10, wherein the solid reducing agent which is used in the mixture that partially fills the reactor is selected from a group which comprises carbon black, charcoal, coke, coal, and wood.
Claim 35
Dependent Claim
34 words
A process according to claim 10, wherein the silicon dioxide which is used in the mixture that partially fills the reactor is selected from a group which comprises quartz, fused silica, and fume silica.
Claim 36
Dependent Claim
28 words
A process according to claim 9, wherein the solid reducing agent is in the form selected from a group which comprises powders, chips, granules, lumps, pellets, and briquettes.
Claim 37
Dependent Claim
33 words
A process according to claim 10, wherein the mixture of silicon dioxide and the solid reducing agent is in the form selected from a group which comprises powders, granules, lumps, pellets, and briquettes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-07-13 | 1991-01-12 | 1991-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-07-13 | 1995-01-12 | 1995-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-07-13 | 1999-01-12 | 1999-07-14 | $7700.00 | Window Closed / Lapsed |