PROCESS FOR PRODUCING SILICON INGOT BY SMELTING SILICON POWDER

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.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] In order to clarify the purpose, solution and advantages for the present invention, with reference to the accompanying embodiments and drawings, the present invention is further described in detail, the embodiments and the illustrations thereof is merely illustrative of the invention and are not intended to limit the invention.

Example 1

[0041] The present invention providing a process for producing a silicon ingot by smelting silicon powder follows the following steps:

[0042] (a11) placing a silicon block or silicon powder in an intermediate induction furnace, and simultaneously adding an iron block to the intermediate induction furnace, wherein a weight ratio of the silicon block to the iron block is 1:1;

[0043] (a12) starting the intermediate induction furnace, setting an operating frequency of the intermediate frequency furnace to 120 HZ, the iron block being heated and heating the silicon, the silicon block reaching its melting point and raising a temperature to 1480-1520 C.;

[0044] (a13) melting the silicon block into a silicon liquid, removing the iron block, and completing furnace starting;

[0045] (b) silicon smelting: adding the silicon power to the silicon liquid for smelting, during the silicon smelting, using a wooden stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute to obtain a silicon liquid; and

[0046] (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.

Example 2

[0047] A process for producing a silicon ingot by smelting silicon powder, comprising following steps:

[0048] (a21) placing a silicon block or silicon powder in an intermediate induction furnace, and simultaneously adding an aluminum ingot to the intermediate induction furnace, wherein a weight ratio of the silicon block to the aluminum ingot is 2:1;

[0049] (a22) starting the induction furnace, setting an operating frequency of the intermediate frequency furnace to 120 HZ to heat the aluminum ingot, and raising a temperature to 700-800 C. to melt the aluminum ingot to an aluminum liquid;

[0050] (a23) continuously raising the temperature to 1700-1800 C. to melt the silicon block or the silicon powder into a silicon liquid;

[0051] (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 induction furnace being full, removing 85%-95% of the mixed liquid and adding anew a silicon block or a silicon powder gradually;

[0052] (a25) repeating step (a24) until the silicon content in the mixed liquid reaching a standard, then completing furnace starting;

[0053] (b) silicon smelting: adding the silicon power to the silicon liquid for smelting, during the silicon smelting, using a wooden stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute to obtain a silicon liquid; and

[0054] (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.

Example 3

[0055] A process for producing a silicon ingot by smelting silicon powder, comprising following steps:

[0056] (a31) placing a silicon block or the silicon powder in an intermediate induction furnace, and simultaneously adding graphite to the intermediate induction furnace, wherein a weight ratio of the silicon block to the graphite is 0.6:1;

[0057] (a32) starting the intermediate induction furnace, setting an operating frequency of the intermediate frequency furnace to 110 HZ, the graphite being heated and heating the silicon, the silicon block reaching its melting point and raising a temperature to 1800-1900 C.;

[0058] (a33) melting the silicon block to a silicon liquid, removing the graphite, and completing furnace starting;

[0059] (b) silicon smelting: adding the silicon power to the silicon liquid for smelting, during the silicon smelting, using a wooden stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute to obtain a silicon liquid; and

[0060] (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.

Example 4

[0061] A process for producing a silicon ingot by smelting silicon powder, comprising following steps:

[0062] (a41) placing silicon powder or a silicon block in an inside of an intermediate induction furnace;

[0063] (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;

[0064] (a43) at the same time as performing step (a42), starting the intermediate induction furnace to raise a temperature, wherein an operating frequency of the intermediate induction furnace is 120-130 HZ; when performing step (a42) and step (a43), the silicon liquid being 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;

[0065] (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;

[0066] (b) silicon smelting: adding the silicon power to the silicon liquid for smelting, during the silicon smelting, using a wooden stick to stir the silicon liquid clockwise or counterclockwise in a single direction, and stir 2-3 cycles per minute to obtain a silicon liquid; and

[0067] (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.

[0068] In the aforementioned four examples, a single capacity of the intermediate induction furnace is 3.5 tons. According to the specification and the prior technology, the capacity can be increased to 5 tons, the single time for furnace starting is from 12 to 15 minutes, and the single smelting time is 80-100 minutes, which greatly improves the production efficiency compared to the production method of the crucible.

[0069] The specific embodiment described above further explains the purposes, technical solutions and beneficial effects of the present invention. It is to be understood that the foregoing is only illustrative of the embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modifications, equivalents, and improvements made within the spirit and scope of the present invention should be included in the scope of protection of the present invention.