PROCESS FOR PRODUCING SILICON INGOT BY SMELTING SILICON POWDER

• US 20190322533A1
• Filed: 12/07/2017
• Published: 10/24/2019
• Est. Priority Date: 12/09/2016
• Status: Active Application

• Current Assignee: Chengdu Silicon Technology Co., Ltd.
• Original Assignee: Chengdu Silicon Technology Co., Ltd.
• Inventors: Yang, Shi, Zhou, Xu
• Application Number:
  US16/467,040
• Publication Number:
  US 20190322533A1
• Time in Patent Office: Days
• CPC Class Codes: B22D 7/005 from non-ferrous metals
• CPC Class Codes: C01B 33/037 Purification by zone-melting C30B13/00

Abstract

A process for producing a silicon ingot by smelting silicon powder, including (a) furnace starting: preparing a silicon liquid having a standard purity in an intermediate frequency furnace; (b) silicon smelting: adding the silicon power to the silicon liquid for smelting, so as to obtain a silicon liquid; and (c) molding: reserving a silicon liquid accounting for 15%-20% of a capacity of the silicon liquid in the intermediate frequency furnace as an initial silicon liquid for a next smelting, and pouring the rest of the silicon liquid into a molding system, thereby producing the silicon ingot. The present invention uses weak conductivity of the silicon liquid to realize induction heating, achieving the purpose of smelting the silicon block. The approach provided by the present invention that uses the induction furnace to smelt silicon can largely improve the production and output efficiency.

Claims

1. A process for producing a silicon ingot by smelting silicon powder, comprising following steps:

(a) furnace starting;

preparing a first silicon liquid having a standard purity in an intermediate frequency furnace;

(b) silicon smelting;

adding the silicon power to the first silicon liquid for smelting, so as to obtain a second silicon liquid; and

(c) molding;

reserving a third silicon liquid accounting for 15%-20% of a capacity of the second silicon liquid in the intermediate frequency furnace as an initial silicon liquid for a next smelting, and pouring the rest of the second silicon liquid into a molding system, thereby producing the silicon ingot.

2. The process of claim 1, wherein in step (a), any one of an iron block furnace starting method, an aluminum block furnace starting method, graphite furnace starting method and an electron beam gun furnace starting method is adopted.

3. The process of claim 2, wherein the iron block furnace starting method comprises following steps:

(a11) placing a silicon block or the silicon powder in an intermediate induction furnace, and simultaneously adding an iron block to the intermediate induction furnace;

(a12) starting the intermediate induction furnace, and raising a temperature to 1480-1520°

C.; and

(a13) melting the silicon block or the silicon powder into a silicon liquid, and removing the iron block.

4. The process of claim 2, wherein the aluminum block furnace starting method comprises following steps:

(a21) placing a silicon block or the silicon powder in an intermediate induction furnace, and simultaneously adding an aluminum ingot to the intermediate induction furnace;

(a22) starting the intermediate induction furnace, and raising a temperature to 700-800°

C. to melt the aluminum ingot to aluminum liquid;

(a23) continuously raising the temperature to 1700-1800°

C. to melt the silicon block or the silicon powder into a silicon liquid;

(a24) gradually adding a silicon block or a silicon powder to the mixed liquid prepared in step (a23), so as to increase a silicon content in the silicon-aluminum mixed liquid; and

as the mixed liquid in the intermediate induction furnace being full, removing 85%-95% of the mixed liquid and adding anew a silicon block or silicon powder gradually; and

(a25) repeating step (a24) until the silicon content in the mixed liquid reaching a standard, then completing the furnace starting.

5. The process of claim 2, wherein the graphite furnace starting method comprises following steps:

(a31) placing a silicon block or the silicon powder in an intermediate induction furnace, and simultaneously adding a graphite block to the intermediate induction furnace;

(a32) starting the intermediate induction furnace, and raising a temperature to 1800-1900°

C.; and

(a33) melting the silicon block and the silicon powder to a silicon liquid, and removing the graphite block.

6. The process of claim 2, wherein the electron beam gun furnace starting method comprises following steps:

(a41) placing the silicon powder or a silicon block in an inside of an intermediate induction furnace;

(a42) starting an electron beam gun, and using the electron beam gun to heat the silicon powder or the silicon bock, so as to prepare a silicon liquid;

(a43) at the same time as performing step (b), starting the intermediate induction furnace to raise a temperature; and

(a44) after the silicon powder or the silicon block completely melting into the silicon liquid, stopping heating of the electron beam gun, and completing the furnace starting.

7. The process of claim 6, wherein in step (b), the silicon liquid is also stirred, wherein an operating procedure is:

using a wood stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute.

8. The process of claim 6, wherein the operating frequency of the intermediate frequency furnace is 100-140 HZ.

9. The process of claim 2, wherein in step (b), the silicon liquid is also stirred, wherein an operating procedure is:

using a wood stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute.

10. The process of claim 3, wherein in step (b), the silicon liquid is also stirred, wherein an operating procedure is:

using a wood stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute.

11. The process of claim 4, wherein in step (b), the silicon liquid is also stirred, wherein an operating procedure is:

using a wood stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute.

12. The process of claim 5, wherein in step (b), the silicon liquid is also stirred, wherein an operating procedure is:

using a wood stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute.

13. The process of claim 6, wherein in step (b), the silicon liquid is also stirred, wherein an operating procedure is:

using a wood stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute.

14. The process of claim 2, wherein the operating frequency of the intermediate frequency furnace is 100-140 HZ.

15. The process of claim 3, wherein the operating frequency of the intermediate frequency furnace is 100-140 HZ.

16. The process of claim 4, wherein the operating frequency of the intermediate frequency furnace is 100-140 HZ.

17. The process of claim 5, wherein the operating frequency of the intermediate frequency furnace is 100-140 HZ.

18. The process of claim 6, wherein the operating frequency of the intermediate frequency furnace is 100-140 HZ.