JPH0539983A - Induction melting furnace - Google Patents

Abstract

PURPOSE:To mechanize the scraping-out work of slag from a melting furnace, where low-level radioactive metallic waste is melted, for protecting workers from being exposed to radiations. CONSTITUTION:The cross-section perpendicular to the vertical axis of a high-frequency induction melting furnace 1 is a shape of a combination of a rectangular part 4 and an arc part 5. The furnace 1 is provided with a slag scraping arm 23 that is tiltable and movable back and forth toward the furnace 1 and has a slag scraper 11 at the tip having an enough width to scrape out the slag over the whole width of the slag when the furnace 1 is tilted to discharge the slag. Therefore, the slag on molten metal can be scraped out by a single scraping operation, thus the slag scraping operation is mechanized and remote operation becomes practical, protecting workers from being exposed to radiations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency induction melting furnace for melting low levelerel radioactive metal waste of 74 Bq / g or less generated when a nuclear facility is dismantled.

[0002]

2. Description of the Related Art In the refining process of steelmaking, slag is produced and then slag is removed to produce steel having a predetermined performance. Since the work of removing slag is a high-heat heavy-duty work, mechanization has long been demanded. 150-3
For large melting furnaces such as 00t converters and 50-100t electric furnaces, various slag removal devices have been filed and published. Of these, typical examples are Japanese Patent Laid-Open No. 61-17895 and Japanese Patent Laid-Open No. 28313/1990 for an electric furnace.

Japanese Patent Application Laid-Open No. 61-17895 discloses that
An advancing / retreating mechanism for moving the scraping rod in the longitudinal direction, a horizontal moving mechanism for horizontally moving the scraping rod, and a swinging mechanism for vertically swinging the tip of the scraping rod are provided at the base of the scraping rod. In Japanese Patent Laid-Open No. 3-283313, a dolly is placed on a slide deck, a breaker having a turning, tilting, and advancing / retreating function is arranged on the dolly, and slag is removed by advancing / retreating the slide deck. It is a thing. Removal of slag in a metal melting furnace of less than 10 tons is performed manually.

[0004]

[Problems to be Solved by the Invention] Scrap generated by the dismantling of nuclear facilities, which is contaminated with low-level radioactivity (hereinafter referred to as low-level radioactive metal waste) is melted in a melting furnace to form an ingot. It is considered that the steel is made, rolled and made into steel, and reused as steel for nuclear facilities. In order to protect workers from radiation exposure in the work process such as charging, melting, and slag of low-level radioactive metal waste in the melting process in this melting furnace,
It is necessary to mechanize as much as possible.

[0005] By simply diverting the conventional slag scraping device considered in a large-scale melting furnace, the scraping plate is reciprocated many times while changing its position in the horizontal direction, so that it takes a lot of work time. ,ineffective.

The present invention is suitable for scraping slag of a small high-frequency induction melting furnace for melting low-level radioactive metal waste, and has an object of mechanization on the premise of remote operation.

[0007]

DISCLOSURE OF THE INVENTION The present invention is intended to achieve the above-mentioned object, and one of them is to form a horizontal cross section perpendicular to the vertical axis of the furnace into a shape combining rectangles and arcs. It is an induction melting furnace characterized by that.

The other one is a melting furnace in which a horizontal section perpendicular to the vertical axis of the furnace has a shape of a combination of a rectangle and an arc, and the substantially entire width of the molten metal surface when the furnace is tilted for slag is scraped. The induction melting furnace is characterized in that a scraping rod having a slag scraping plate having a width for discharging is provided so as to be tiltable and movable in the furnace direction.

The induction melting furnace is preferably a high-frequency induction melting furnace in which the operation can be started and stopped easily and there is no electrode or the like at the furnace top or its periphery.

[0010]

Since most of the horizontal section perpendicular to the vertical axis of the furnace of the melting furnace is a rectangular portion, a scraping plate having a width substantially equal to the entire width of the molten metal surface can be used. As a result, the slag on the entire surface of the molten metal can be scraped with a single scraping operation.

Since the scraping rod provided with the scraping plate at the tip is swingable and can be moved back and forth in the furnace direction, the scraping of the slag can be carried out mechanically, thereby enabling remote operation.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 is an explanatory view of a melting furnace according to the present invention, FIG. 2 is a plan view of the melting furnace mounted on a trolley as seen from above, FIG. 3 is a sectional view of a tap hole, and FIG. 4 is installed in a closed compartment. FIG. 5 is a diagram showing a melting furnace and the like, and FIG. 5 is an explanatory diagram of a drive unit of the slag scraping bar.

In FIG. 4, a high-frequency induction melting furnace 1 (hereinafter abbreviated as a melting furnace) placed on a carriage 30 movable on the floor 40, and a carriage 31 movable on the floor 40. A mold 32 and a slag pan 33, a tundish 35 for guiding molten steel or slag to the mold or slag, and a slag scraping device 10 are housed in a closed compartment 41.
A suction hood 36 is provided on the ceiling wall 42 of the closed compartment, and the suction hood 36 is sucked by a fan (not shown) so that the inside of the closed compartment is-
It is kept at 5-10mmAq. Therefore, fumes and solid particles generated during the melting operation of the low-level radioactive metal scrap are sucked through the suction hood 36, and there is no risk of leaking from the sealed compartment to the safety compartment.

In FIGS. 1, 2 and 5, the melting furnace 1 placed on the carriage 30 is indicated by a solid line by a tilting device (not shown) provided on the carriage 30 during tapping and tapping. It can be tilted in the direction of the tap hole 3. The melting furnace 1 has a horizontal cross section perpendicular to the vertical axis formed in a shape in which a rectangular portion 4 and an arc portion 5 are combined over the entire length of the vertical axis, and the width of the rectangular portion 4 is the same over the entire length of the vertical axis. The width of the tap hole 3 is the same as the width of the rectangular portion 4.

On the other hand, a rail 19 is laid on the work deck 6 in parallel with the moving direction of the moving truck 30 of the melting furnace, and a truck 17 having traveling wheels 18 is placed thereon. A small carriage 20 that moves in a direction orthogonal to the rails 19 is provided on the carriage 30. The small carriage 20 moves via a bracket 22 by operating a hydraulic / pneumatic cylinder 21 provided on the carriage 17. It is supposed to do.

A support bracket 15 is erected on the small dolly 20, and a trunnion shaft 42 of the hydraulic / pneumatic cylinder 12 is pivotally attached to an upper portion of the support bracket 15 so as to be vertically rotatable. A scraping rod 23 is attached to the tip of the cylinder rod 13 of the hydropneumatic cylinder 12, and the tip of the scraping rod 23 has a size to scrape almost the entire width of the molten metal surface when the furnace is tilted for sludge. A scraping plate 11 having a width of is fixed. A hydraulic / pneumatic cylinder 16 is provided between the support bracket 15 and the middle of the hydraulic / pneumatic cylinder 12, and the rear end of the hydraulic / pneumatic cylinder 16 is located below the support bracket 15 and the tip of the cylinder rod is hydraulically / pneumatically. It is pivotally attached in the middle of the pressure cylinder 12.

Next, a method of scraping slag will be described. After the melting of the low-level radioactive metal waste is completed, the melting furnace 1 is tilted at a predetermined angle to make the slag surface in the furnace horizontal. The carriage 17 is moved, and the shaft center of the scraping bar 13 is moved to the melting furnace 1
Align with the center of. The cylinder rod of the hydraulic cylinder 20 is extended to move the small truck 20 to the end of the truck 17 on the melting furnace side. The cylinder rod 13 of the hydraulic / pneumatic cylinder 16 is extended, and while operating the cylinder rod of the hydraulic / pneumatic cylinder 16, the scraping plate 11 is positioned deep in the molten metal surface.

The cylinder rod 13 of the hydraulic / pneumatic cylinder 16 is contracted, the cylinder rod of the hydraulic / pneumatic cylinder 16 is extended to lower the scraping plate 11, and the slag on the surface of the molten metal is scraped out to make the tapping hole 3 , Through the dandy 35 to the slag pan 33. After the slag is finished, hydraulic / pneumatic cylinder 2
1 is operated to retract the small truck 20.

[0019]

Since the high frequency melting furnace of the present invention is constructed as described above, the following effects can be obtained. (1) Since most of the cross-section of the melting furnace is rectangular, a scraping plate having a width almost the entire width of the molten metal surface can be inserted to the deep part of the slag surface, and the molten metal surface can be removed by one scraping operation. You can scrape out the upper slag. That is, slag scraping can be performed in a short time. (2) Since the slag scraping device is small, mechanized, and simplified, it is possible to safely perform remote control, and it is possible to prevent radiation exposure without requiring an operator to approach the melting furnace.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a melting furnace according to the present invention.

FIG. 2 is a plan view of a melting furnace mounted on a trolley as viewed from above.

FIG. 3 is a cross-sectional view of a tap hole.

FIG. 4 is a view showing a melting furnace and the like installed in a closed compartment.

FIG. 5 is an explanatory diagram of a drive unit of the slag scraping bar.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High frequency induction melting furnace 3 Steel tap 4 Rectangular part 5 Arc part 6 Work deck 10 Slag scraping device 11 Scrape plate 12 Hydraulic / pneumatic cylinder 13 Cylinder rod 14 Hydraulic / pneumatic cylinder tip 15 Support bracket 16 Hydraulic / pneumatic cylinder 17 Trolley 21 Hydro-pneumatic cylinder

Claims (2)

[Claims] 1. An induction melting furnace characterized in that the horizontal cross section perpendicular to the vertical axis of the furnace is formed by combining rectangles and arcs. 2. A smelting furnace having a horizontal cross section perpendicular to the vertical axis of the furnace in the shape of a combination of rectangles and arcs, and having a size of scraping out substantially the entire width of the molten metal surface when the furnace is tilted to remove slag. An induction melting furnace characterized in that a slag scraping plate having a width is provided at a tip thereof so as to be tiltable and movable forward and backward in a furnace direction.