DE102017114859A1 - Apparatus for selectively controlling the tapping operation of a melt from an electric arc furnace - Google Patents

Abstract

Apparatus for selectively controlling the smelting and slagging operation during a campaign for an electric arc furnace formed with a tapping area. Wherein the tapping opening (17) associated with the tapping area (13) on the inboard side (18) of the electric arc furnace (11) forming vessel (19), with a float (12) is operatively connected and the float (12) during the tapping operation with the outflowing flow of melt (14) and slag (15) from the vessel (19) the tapping opening (17) partially closes, so that a Abstichreihenfolge of melt (14) before slag (15) is adjustable.

Description

The present invention relates to an apparatus for selectively controlling the smelting and slagging operation during a campaign for an electric arc formed with a tapping area.

With electric arc furnaces (EAF) for smelting steel scrap - for reuse as new steel product - all steel grades can be produced. However, due to the high costs, they are mainly used for the production of quality and stainless steels. In addition to the liquid crude steel, a slag layer forms on the melt from the non-metallic starting materials and oxides of the alloying materials. This has the task of binding unwanted components and protecting the steel bath from further oxidation and heat loss and the oven from overheating.

In order to lower the operating costs of electric arc furnaces over the amount of steel produced, a maximum utilization of such systems is desirable. This includes a particularly effective tapping of the steel in order to serve the following processing rods with as pure as possible precursors and to keep the Committee on slag-contaminated crude steel as low as possible.

In electric arc furnaces in which the melt is poured into a ladle via a snout (tapping area) (so-called snout dippers or bay furnaces), the slag is always tapped. This is predetermined by the geometry of such trained electric arc furnaces. However, there is still a variant of the oven with a siphon, in which slag can usually be tapped.

However, there is no simple and cost-effective solution known in which in a campaign, (producing multiple melts in the same furnace in several cycles of melting and parting) once with slag and once without slag is tapped, without causing loss of production and / or or delay by retooling the electric furnace comes.

It is therefore an object of the present invention to overcome the above-mentioned disadvantages and to enable a cost-effective production of molten steel with an electric arc furnace in at least one campaign.

This object is achieved on the basis of the preamble in conjunction with the characterizing features of claim 1. Advantageous developments are the subject of dependent claims.

According to the teachings of the invention, the tap hole associated tapping opening on the inner side of the electric arc furnace forming vessel can be brought into operative connection with a float and the float during the tapping process with the outflow of melt and slag from the vessel partially closes the tap opening, so a tapping order of melt before slag is adjustable.

In a particularly preferred embodiment of the device according to the invention, the specific gravity of the floating body is adjusted to the specific density of melt and slag, so that the floating body is lighter than the melt and heavier than the slag.

According to a further preferred embodiment of the device according to the invention, the floating body partially floats on the melt / slag interface.

It is intended that the float too 1 / 4 his body in the melt and to 3 / 4 his body floats in the slag.

In a further preferred embodiment of the device according to the invention, it is provided that the floating body is formed substantially as a spherical body. Also, the float may be formed as a polyhedron or dodecahedron.

In a particularly advantageous embodiment of the device according to the invention, the center of gravity of the float is very deep, so that it comes with each change in the position of the float in this to a lifting of the center of gravity, thereby characterized the float by the force acting on it gravity with respect to the interface layer stabilized between melt and slag.

In order to avoid caking and thus a possible center of gravity displacement or even a descent of the device in the melt, it is provided to provide the float with a surface coating having a Lotoseffekt. The lotus effect refers to the low wettability of a surface, as can be observed in the lotus plant. Melt and slag emit into droplets, taking with them all the dirt particles on the surface of the float. Responsible for this is a complex micro- and nanoscopic architecture of the surface, which should minimize the adhesion of dirt particles.

It is envisaged that the float will be designed so that its internal and external structure will allow it to be reused for a variety of campaigns. This also includes a simple and inexpensive retreading or repair and repair of damage. Particularly advantageous may be a shell-like or layer-like construction of the float. The individual layers can be packed in different densities and have different heat conduction coefficients.

As an outer layer, as a kind of Ummantlung a ceramic layer is conceivable, followed by a heat-insulating layer and a very dense high-mass layer, which can also form the core. In this case, the center of gravity can be eccentric.

So that the float during a campaign in which the melt can be tapped once with and once without slag in pans provided for this purpose, the float body holding means are assigned, via which it can be taken out or used accordingly from the vessel of the electric arc furnace. It is envisaged that the device according to the invention will be used essentially in stainless steel furnaces.

• 1 die Seitenansicht in einem Schnitt durch einen, als Schnauzenkipper ausgebildeten Elektrolichtbogenofen (EAF) in einer horizontalen nicht gekippten Arbeitsstellung, wobei der Schwimmkörper auf der innen-liegenden Seite der Abstichöffnung so angeordnet ist, dass dieser die Schlacke im Gefäß des EAF zurückhalten kann und den Eintritt der Schlacke in die Abstichöffnung verhindert;
• 2 die Seitenansicht in einem Schnitt nach 1, wobei der EAF in einer Abstichposition gekippt ist und die Schmelze über die Abstichöffnung aus dem Gefäß des EAF austreten kann, wobei die Schlacke von dem Schwimmkörper im Gefäß zurückgehalten wird.

The invention will be explained in more detail below with reference to an exemplary embodiment with reference to the accompanying drawings. The figures show:

• 1 the side view in a section through an electric arc furnace (EAF) designed as a snout dipper in a horizontal non-tilted working position, wherein the float is arranged on the inside lying side of the tap hole so that it can withhold the slag in the vessel of the EAF and the entrance the slag in the taphole prevents;
• 2 the side view in a section after 1 wherein the EAF is tilted in a tapping position and the melt may exit the vessel of the EAF via the tapping opening, the slag being retained by the float in the vessel.

Like in the 1 shown is the device 10 essentially as a spherical float 12 educated. If during a campaign, the melt without the slag in a pan (not shown) are tapped, so the float 12 into the vessel 19 of the electric arc furnace 11 be lifted into it. It is advantageous if the float 12 in front of the exit opening 17 on the inner side 18 of the vessel 19 is placed. The electric arc furnace 11 may preferably be a furnace for the production of stainless steels.

Here is the float 12 designed so that it is at the interface between melt 14 and slag 15 swims. It is advantageous if the float is balanced so that it to a quarter of its circumference in the melt 14 Floats and three quarters in the slag 15 is arranged in such a way that a flushing of the float 12 through the slag 15 under normal process conditions is not possible.

2 shows the EAF in a tilted position in which the tapping is to be done without slag. Here is the float 12 always parallel to the surface 16 the melt 14 regardless of the level of the vessel 19 , The melt 14 is through the tap hole 17 over one, the electric arc furnace 11 associated tulle-like tapping area 13 from the vessel 19 derived. This is the slag 15 retained by the float, so that it does not fall into the outlet opening even with sinking melt level 17 can get.

LIST OF REFERENCE NUMBERS

10

contraption

11

Electric arc furnace

12

float

13

the tapping

14

melt

15

slag

16

Surface melt

17

tapping opening

18

inside page

19

vessel

Claims (11)

Device for the selective control of the melting process of slag and slag during a campaign for an electric arc furnace, which is formed with a tapping region, characterized in that the tapping region (17) associated with the tapping region (13) on the inner side (18) of the electric arc furnace ( 11) forming the vessel (19) with a float (12) is operatively connected and the float (12) during the tapping process with the outflowing flow of melt (14) and slag (15) from the vessel (19) the tapping opening (17 ) partially closes, so that a Tapping order of melt (14) before slag (15) is adjustable. Device after Claim 1 , characterized in that the specific gravity of the floating body (12) is adjusted to the specific density of melt and slag, so that the floating body is lighter than the melt (14) and heavier than the slag (15). Device after Claim 2 , characterized in that the floating body (12) at the interface (16) between the melt (14) and slag (15) partially floats. Device after Claim 3 , characterized in that the float (12) floats to 1/4 of its body in the melt (14) and to 3/4 of its body in the slag (15). Device after Claim 4 , characterized in that the floating body (12) is formed substantially as a spherical surface body. Device after Claim 4 , characterized in that the floating body (12) is designed as a polyhedron. Device after Claim 6 , characterized in that the float is a dodecahedron. Device according to the Claims 1 to 7 , characterized in that the center of gravity of the floating body (12) is very deep, so that it comes with each change in the position of the float (12) in this to a lifting of the center of gravity, thereby characterized the float (12) by the force acting on it gravity is position stabilized with respect to the interface (16) between the melt (14) and slag (15). Device after Claim 7 , characterized in that the floating body (12) has a surface coating with lotus effect. Device according to one or more of the preceding Claims 1 to 9 , characterized in that the float (12) is reusable. Device after Claim 10 , characterized in that the float (12) holding means are assigned, via which it can be removed or inserted from the vessel (19).

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