HOOD FOR SI-METAL TAPPING

Abstract

A hood for a taphole and a tapping spout in a submerged arc furnace in the production of silicon. The hood has at least two suction ducts which are placed asymmetrically on either side of the hood, and is useful in a process for the production of silicon in a submerged arc furnace, wherein liquid silicon and refining gas escape from a taphole of a crucible, wherein the liquid silicon flows on a tapping spout into a ladle, wherein the refining gas is sucked in a hood which has at least two suction ducts which are placed on either side of the hood.

Claims

1.-10. (canceled)

11. A hood for a taphole and a tapping spout in a submerged arc furnace for the production of silicon wherein the hood has at least two suction ducts placed asymmetrically on either side of the hood.

12. A process for the production of silicon in a submerged arc furnace, wherein liquid silicon and refining gas escape from a taphole of a crucible, wherein the liquid silicon flows on a tapping spout into a ladle, wherein the refining gas is sucked in a hood which has at least two suction ducts which are placed asymmetrically on either side of the hood.

13. The hood of claim 11, wherein one suction duct is placed close to the taphole, thus ventilating gas emitted from the crucible and the other suction duct is placed over the ladle into which the liquid silicon flows, for capturing fume emitted by the refining process.

14. The hood of claim 11, wherein the refining or the tapping gas is sucked by pipes which are connected with the suction ducts that are oriented vertically immediately after their connection point on either side of the hood.

15. The hood of claim 11, wherein the ducts have manhole openings.

16. The hood of claim 11, wherein the hood walls are slopped.

17. The process of claim 12, wherein one suction duct is placed close to the taphole, thus ventilating gas emitted from the crucible and the other suction duct is placed over the ladle into which the liquid silicon flows, for capturing fume emitted by the refining process.

18. The process of claim 12, wherein the refining or the tapping gas is sucked by pipes which are connected with the suction ducts that are oriented vertically immediately after their connection point on either side of the hood.

19. The process of claim 12, wherein the ducts have manhole openings.

20. The process of claim 12, wherein the hood walls are slopped.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a front view of one embodiment of the invention.

[0010] FIG. 2 is a perspective view of the embodiment of FIG. 1 FIG. 3 is a top view of the embodiment of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The hood according to the invention uses at least two suction ducts (3) instead of the usual single suction duct (3) and therefore provides improved suction of the gas emitted from the taphole (4) when compared to the conventional designs while it manages to comply with the aforementioned restrictions.

[0012] If the ducts (3) are located on the same side of the hood (1), then the suction will not be uniform and the gas may escape on the other side of the hood (1).

[0013] Preferably, the hood (1) features a suction system that rotates together with the hood (1) and the crucible (7).

[0014] Preferably, the hood (1) has two suction ducts (3) which are placed asymmetrically on either side of the hood (1).

[0015] The asymmetrical position avoids that the gas flow can have a stagnation point halfway between the two ducts (3) and that the suction can be inadequate.

[0016] However, if the ducts (3) are placed asymmetrically opposite each other, then no stagnation point will appear, thus improving the suction.

[0017] Preferably, one suction duct (3) is placed close to the taphole (4), thus ventilating the gas emitted from the crucible (7) and the other suction duct (3) is placed over the ladle (5) into which the liquid silicon flows for capturing the fume emitted by the refining process.

[0018] Preferably, the refining gas or the tapping gas is sucked by pipes (6) which are connected with the suction ducts (3).

[0019] Preferably, both suction pipes (6) are oriented vertically immediately after their connection point to the hood (1). This causes the gas to flow downwards as soon as it enters the duct (3). In this way the microsilica particles contained in the gas cannot sediment and stick on the inner walls of the pipes (6) and clogging risk of the ducts (3) is thus reduced.

[0020] In a preferred embodiment, the pipes (6) have manhole openings which facilitate cleaning of the hood (1) and the pipes (6).

[0021] In a preferred embodiment, in order to further minimize the amount of smoke that may escape, the hood (1) walls are slopped whenever possible instead of being horizontal or vertical. This minimizes the hood inner volume and eliminates stagnant volume regions in which suction is poor and smoke can accumulate. Preferably the side walls of the hood (1) are slopped.

[0022] The hood decreases the amount of flue gas that manages to escape the ventilation system and enter the working environment. This results into better working conditions for the people operating the tapping equipment by improving the air quality and by reducing the dust accumulation in the tapping area.

[0023] In a preferred embodiment, the hood material is steel.

[0024] FIGS. 1 to 3 show the hood (1) according to the invention placed above the ladle (5) from different views. FIG. 1 is a front view, FIG. 2 is a perspective view and FIG. 3 is a top view.

[0025] FIGS. 1 to 3 show the hood (1) which covers the tapping spout (2) where liquid silicon is flowing into the ladle (5). Two suction ducts (3) are used for capturing the tapping and the refining gas from the taphole (4) and the tapping spout (2) which are connected with the crucible (7). The gas is sucked by pipes (6) which are connected with the suction ducts (3).

[0026] In addition the two ducts (3) are located on opposite sides of the hood (1) in an asymmetric manner. The two pipes (6) are oriented vertically after their connection point to the hood (1). The hood (1) has sloped surfaces.