Method for producing technical silicon

Patent metadata

Field	Value
Publication number	US-12157671-B2
Application number	US-201917441529-A
Country	US
Kind code	B2
Filing date	Mar 22, 2019
Priority date	Mar 22, 2019
Publication date	Dec 3, 2024
Grant date	Dec 3, 2024

Abstract

Technical-grade silicon is produced by reacting a raw material mixture containing silicon dioxide and carbon in an electric furnace with a particulate mediator containing at least one of the elements C, O, Al and Si is reacted in an electric furnace, wherein the mixture is described by a dimensionless index K, K having a value of from 0 to 745 and being calculated as follows:K=ωM·βR⁢M·μC⁢where:equation⁢(1)ωM=6·(1-εm,M)d50,Mequation⁢(2)βR⁢M=d9⁢0,R⁢M-d1⁢0,R⁢Mequation⁢(3)μC=32-mMmR⁢Mequation⁢(4)where the meanings of ωM, εm,M, βRM, μC, d50,M, d90,RM, mM and mRM are explained in claim 1.

First claim

The invention claimed is:

1. A method for producing technical-grade silicon by carbothermic reduction of silicon dioxide by carbon in an electric furnace, comprising:
supplying a reactant mixture comprising silicon dioxide and carbon, together with a particulate mediator comprising elemental silicon, SiC, or a mixture thereof to the electric furnace, and reacting to form metallic silicon from the reactant mixture,
wherein a mixture of the reactant mixture and particulate mediator is described by a dimensionless index K, calculated as follows:

K
=

ω
M

·

β

R
⁢
M

·

μ
C

⁢

where
:

equation
⁢

(
1
)

ω
M

=

6
·

(

1
-

ε

m
,
M

)

d

50
,
M

equation
⁢

(
2
)

β

R
⁢
M

=

d

9
⁢
0

,

R
⁢
M

-

d

1
⁢
0

,

R
⁢
M

equation
⁢

(
3
)

μ
C

=

3
2

-

m
M

m

R
⁢
M

equation
⁢

(
4
)

where:
ω M is a characteristic surface area-to-volume coefficient of the particulate mediator [1/mm]
ε m,M is the mean effective porosity of the particulate mediator, and ranges from 0 to 0.95,
β RM is the breadth of a particle size distribution of the reactant mixture [mm]

m
M

m

R
⁢
M

is the mass ratio of particulate mediator to reactant mixture in the mixture
d 50,M is the particle size (diameter) at 50% of the mass undersize of the grading curve of the particulate mediator [mm]
d 90,RM is the particle size (diameter) at 90% of the mass undersize of the grading curve of the reactant mixture [mm]
d 10,RM is the particle size (diameter) at 10% of the mass undersize of the grading curve of the reactant mixture [mm]
m M is the mass of the particulate mediator in the mixture [kg]
m RM is the mass of the reactant mixture in the mixture [kg],

wherein K has a value within the range of from 0 to 745.

2. The method of claim 1 , in which the silicon residues are by-products and/or wastes arising from the production of elemental silicon or in the mechanical treatment of elemental silicon.

3. The method of claim 2 , in which the particulate mediator contains at least 10% by mass of elemental silicon residues.

4. The method of claim 1 , wherein the particulate mediator contains from 30-95 wt. % of silicon in elemental form.

5. The method of claim 1 , in which the proportion of the particulate mediator in

Assignees

• Wacker Chemie Ag

Inventors

• Rimboeck Karl-Heinz

Classifications

• C01P2006/80

  Compositional purity · CPC title

• C01B33/037 Primary

  Purification (by zone-melting C30B13/00) · CPC title

• C01B33/025 Primary

  with carbon or a solid carbonaceous material, i.e. carbo-thermal process · CPC title