PURIFICATION OF A METALLOID BY CONSUMABLE ELECTRODE VACUUM ARC REMELT PROCESS

• US 20160258684A1
• Filed: 05/15/2016
• Published: 09/08/2016
• Est. Priority Date: 08/26/2011
• Status: Abandoned Application

• Current Assignee: Consarc Corporation (Inductotherm Group)
• Original Assignee: Consarc Corporation (Inductotherm Group)
• Inventors: ROBERTS, Raymond J.
• Application Number:
  US15/155,045
• Publication Number:
  US 20160258684A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C01B 33/037 Purification by zone-melting C30B13/00
• CPC Class Codes: C30B 11/003 Heating or cooling of the melt or the crystallised material
• CPC Class Codes: C30B 29/06 Silicon
• CPC Class Codes: F27B 14/06 heated electrically, e.g. induction crucible furnaces with or without any other source of heat F27B14/04 takes precedence
• CPC Class Codes: F27B 14/14 Arrangements of heating devices
• CPC Class Codes: F27B 2014/068 with the use of an electrode producing a current in the melt
• CPC Class Codes: Y02P 20/129 Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Abstract

A metalloid such as silicon in the form of a preheated solid electrode is purified by a CEVAR purification process by producing an ingot with controlled heating and cool down after the preheated electrode is melted in a CEVAR furnace system using a short CEVAR open-bottomed crucible.

Claims

1. A CEVAR furnace system for producing a purified silicon ingot from a silicon electrode, the CEVAR furnace system comprising:

a silicon electrode heating apparatus for preheating the silicon electrode to form a preheated silicon electrode;

a gas-tight CEVAR furnace chamber;

a short CEVAR open-bottomed crucible for containment of an arc zone from a CEVAR purification process melting the preheated silicon electrode, the short CEVAR open-bottomed crucible disposed in the gas-tight CEVAR furnace chamber;

a preheated silicon electrode drive system for lowering the preheated silicon electrode within the short CEVAR open-bottomed crucible as a lower end of the preheated silicon electrode melts in the CEVAR purification process;

an ingot heating apparatus disposed adjacent to the open bottom of the short CEVAR open-bottomed crucible through which the purified silicon ingot formed in the CEVAR purification process passes;

an ingot heating controller for controlling the ingot heating apparatus to provide a temperature-controlled thermal environment for the purified silicon ingot passing through the ingot heating apparatus; and

an ingot withdrawal drive system for alternatively withdrawing the purified silicon ingot from the short CEVAR open-bottomed crucible at a vertical growth rate of the purified silicon ingot during steady state of the CEVAR purification process or raising the short CEVAR open-bottomed crucible, the silicon electrode and the ingot heating apparatus at the vertical growth rate of the purified silicon ingot during steady state of the CEVAR purification process.

2. The CEVAR furnace system of claim 1 wherein an interior height of the short CEVAR opened-bottom crucible is at least 60 percent and less than 120 percent of a diameter of the purified silicon ingot formed in the CEVAR purification process.

3. The CEVAR furnace system of claim 1 further comprising a vacuum lock chamber connected between the silicon electrode heating apparatus and the short CEVAR opened-bottom crucible in the gas-tight CEVAR furnace chamber to prevent exposure to air of the preheated silicon electrode during transfer from the silicon electrode heating apparatus to the gas-tight CEVAR furnace chamber.

4. The CEVAR furnace system of claim 3 wherein the silicon electrode heating apparatus comprises a resistance furnace.

5. The CEVAR furnace system of claim 1 further comprising an auxiliary electrode heater disposed within the gas-tight CEVAR furnace chamber to heat the preheated silicon electrode during the CEVAR purification process.

6. The CEVAR furnace system of claim 1 further comprising a thermal insulation disposed around the preheated silicon electrode in the gas-tight CEVAR furnace chamber.

7. The CEVAR furnace system of claim 6 wherein the thermal insulation comprises a carbon fiber insulating material.

8. The CEVAR furnace system of claim 1, the base having a contour for interlocking contact with the bottom of the purified silicon ingot.

9. The CEVAR furnace system of claim 1, the short CEVAR opened-bottom crucible having an interior wall with a rectangular cross section, the interior height of the short CEVAR opened-bottom crucible being at least 60 percent and less than 120 percent of the length of a rectangular side of the purified silicon ingot formed in the CEVAR purification process.

10. The CEVAR furnace system of claim 1, the ingot withdrawal drive system further comprising a base upon which the bottom of the purified silicon ingot sits and a drive actuator connected to the base to control the rate of withdrawing of the purified silicon ingot from the short CEVAR open-bottomed crucible.

11. The CEVAR furnace system of claim 10 further comprising a DC power source having a first output and a second output connected respectively between the preheated silicon electrode and the base or the drive actuator.

12. The CEVAR furnace system of claim 1 further comprising a continuous preheated silicon electrode furnace charging apparatus for forming the purified silicon ingot with the CEVAR furnace system as a continuous purified silicon ingot.

13. A CEVAR furnace system for producing a purified silicon ingot from a silicon electrode, the CEVAR furnace system comprising:

a gas-tight CEVAR furnace chamber;

a silicon electrode heating apparatus disposed within the gas-tight CEVAR furnace chamber for preheating the silicon electrode to form a preheated silicon electrode;

a short CEVAR open-bottomed crucible for containment of an arc zone from a CEVAR purification process melting the preheated silicon electrode, the short CEVAR open-bottomed crucible disposed in the gas-tight CEVAR furnace chamber;

a preheated silicon electrode drive system for lowering the preheated silicon electrode within the short CEVAR open-bottomed crucible as a lower end of the preheated silicon electrode melts in the CEVAR purification process;

an ingot heating apparatus disposed adjacent to the open bottom of the short CEVAR open-bottomed crucible through which the purified silicon ingot formed in the CEVAR purification process passes;

an ingot heating controller for controlling the ingot heating apparatus to provide a temperature-controlled thermal environment for the purified silicon ingot passing through the ingot heating apparatus; and

an ingot withdrawal drive system for alternatively withdrawing the purified silicon ingot from the short CEVAR open-bottomed crucible at a vertical growth rate of the purified silicon ingot during a steady state of the CEVAR purification process or raising the short CEVAR open-bottomed crucible, the silicon electrode and the ingot heating apparatus at the vertical growth rate of the purified silicon ingot during the steady state of the CEVAR purification process.

14. The CEVAR furnace system of claim 13 wherein an interior height of the short CEVAR opened-bottom crucible is at least 60 percent and less than 120 percent of a diameter of the purified silicon ingot formed in the CEVAR purification process.

15. The CEVAR furnace system of claim 13 further comprising a thermal insulation disposed around the preheated silicon electrode in the gas-tight CEVAR furnace chamber.

16. The CEVAR furnace system of claim 15 wherein the thermal insulation comprises a carbon fiber insulating material.

17. The CEVAR furnace system of claim 13, the base having a contour for interlocking contact with the bottom of the purified silicon ingot.

18. The CEVAR furnace system of claim 13, the short CEVAR opened-bottom crucible having an interior wall with a rectangular cross section, the interior height of the short CEVAR opened-bottom crucible being at least 60 percent and less than 120 percent of the length of a rectangular side of the purified silicon ingot formed in the CEVAR purification process.

19. The CEVAR furnace system of claim 13, the ingot withdrawal drive system further comprising a base upon which the bottom of the purified silicon ingot sits and a drive actuator connected to the base to control the rate of withdrawing of the purified silicon ingot from the short CEVAR open-bottomed crucible.

20. The CEVAR furnace system of claim 19 further comprising a DC power source having a first output and a second output connected respectively between the preheated silicon electrode and the base or the drive actuator.