Ladle bottom and ladle

Abstract

A ladle bottom being part of a metallurgical ladle for treating a metal melt as well as a corresponding metallurgical ladle.

Claims

1. Ladle bottom made of a refractory ceramic body with an upper surface, a lower surface and a pouring channel extending between upper surface and lower surface, wherein said pouring channel extends from a diffusor box, being defined by a deepened section of said upper surface, wherein the diffusor box is characterized by the following features: a) it is arranged at a horizontal distance to a surface area of the ladle bottom used as an impact area for a metal melt poured onto said ladle bottom, b) it has a vertical step at least along its border facing the impact area, wherein said step has a height of between 40 and 200 mm, c) it has a minimum horizontal area $A_{min}=\frac{\Pi }{4}{\left(0.37r\right)}^2+0.3$ and a maximum horizontal area $A_{\max }=\frac{\Pi }{4}{\left(0.08r\right)}^2+0.3$ wherein r=radius of the ladle bottom and r≧0.75 m with r.sub.max=2 m for all ladle bottoms with an effective radius of ≧2 m, d) an inlet end of said pouring channel is arranged offset the step along its border facing the impact area.

2. Ladle bottom according to claim 1, wherein the step extends along at least 75% of the border of the diffusor box.

3. Ladle bottom according to claim 1, wherein the step extends along the complete border of the diffusor box.

4. Ladle bottom according of claim 1, wherein the border defining the outer geometry of the diffusor box has a rectangular, circular or oval shape.

5. Ladle bottom according to claim 1 wherein the horizontal area of the diffusor box corresponds to 3.7 to 32.9% of the total surface area of the ladle bottom.

6. Ladle bottom according to claim 5 wherein the horizontal area of the diffusor box is equal or larger than 5.8% of the total surface area of the ladle bottom.

7. Ladle bottom according to claim 5 wherein the horizontal area of the diffusor box is equal or smaller than 25.5% of the total surface area of the ladle bottom.

8. Ladle bottom according to claim 1 wherein the pouring channel is arranged at a distance to the step along its border facing the impact area being equal or larger 3 times its maximum horizontal extension.

9. Ladle bottom according to claim 1 with a distance between a central point along the upper surface of the impact area and a central point along the upper surface of the diffusor box being 30 to 75% of the maximum horizontal extension of the ladle bottom.

10. Ladle bottom according to claim 1 with a distance between a central point along the upper surface of the impact area and a central point along the upper surface of the diffusor box being 50 to 65% of the maximum horizontal extension of the ladle bottom.

11. Ladle bottom according to claim 1 with a distance between a central longitudinal axis of a gas purging plug arranged in the ladle bottom and a central point along the upper surface of the diffusor box being 30 to 75% of the maximum horizontal extension of the ladle bottom.

12. Ladle bottom according to claim 1 with a distance between a central longitudinal axis of a gas purging plug arranged in the ladle bottom and a central point along the upper surface of the diffusor box being 50 to 65% of the maximum horizontal extension of the ladle bottom.

13. Ladle bottom according to claim 1 with a dam like protrusion between impact area and diffusor box, extending substantially perpendicular to a direction along which a corresponding metal melt will flow from the impact area into the diffusor box after hitting the impact area.

Description

(1) The attached drawing schematically represents in

(2) FIG. 1 a prior art ladle in a longitudinal sectional view and a top view

(3) FIG. 2 a ladle according the invention in a longitudinal sectional view and a top view

(4) FIG. 3 an enlarged longitudinal section of the slightly different shape of a diffusor box with adjacent components

(5) The same numerals are used for parts providing the same or at least similar features.

(6) The ladle of FIG. 1 has a circular, horizontally extending bottom 10 with an upper horizontal surface 10o and a lower horizontal surface 10u. A substantially cylindrical ladle wall 12 extends upwardly from the outer periphery 10p of ladle bottom 10. An open upper end of the ladle is symbolized by numeral 14.

(7) A metal stream MS is shown by arrow M, entering the ladle by its open end 14, flowing vertically downwardly before hitting an impact area 10i of the upper surface 10u of ladle bottom 10.

(8) At least part of the metal stream continues its flow (arrow F) towards a pouring channel 16 arranged offset to said impact area 10i, which pouring channel 16 runs from upper surface 10u to lower surface 10o.

(9) As shown in FIG. 1 the said pouring channel 16 is filled with a so called filling sand FS and a sand cone SC may be seen on top of channel 16. The filler material keeps the metal melt off the channel during filling the ladle. It serves to avoid unintended tapping when the ladle is filled. Insofar it has an important function within the casting process.

(10) In a prior ladle according to FIG. 1 the sand SC may be flushed away by the melt stream (arrow F), causing serious uncertainties and risks in the following casting process. This filler material is further at least partially flushed away in case of a gas treatment of the melt by gas purging plugs, one of which is shown and represented by GP.

(11) The new ladle design according to FIG. 2, 3 provides a diffusor box DB around said pouring channel 16 and offset (at a distance to said) impact area 10i.

(12) The diffusor box DB is characterized by a recess within upper surface 10o, i.e. a section deepened with respect to the adjacent areas of upper surface 10o and thus providing a step S along the border (borderline) B of said diffusor box DB. The upper surface section of diffusor box DB is referred to as 10od. The vertical part of said step S forms a right angle with respect to both adjacent sections of the upper bottom surface 10o/10od.

(13) The diffusor box DB has a mainly rectangular upper surface 10od. A well nozzle 18 (German: Lochstein) is arranged in the bottom portion 10d of the diffusor box DB.

(14) The central through opening of said well nozzle 18 defines an upper part of pouring channel 16.

(15) An inner nozzle 20—known per se—is arranged within the lower part of said well nozzle 18, followed in a conventional way by a sliding gate with sliding plates 24, 26 and an outer nozzle 22, defining the middle and lower part of the pouring channel 16.

(16) The pouring channel 16 is filled with filler sand FS, including a sand cone SC on top of well nozzle 18—similar to FIG. 1—.

(17) The dimensions of said diffusor box DB are as follows: height h of step S: 100 mm length: 1370 mm, width: 1085 mm diameter of pouring channel 16 along nozzles 20,22: 80 mm distance between a central point CP1 of the impact area 10i (along the upper surface 10u) and a central point CP2 along the upper surface of the diffusor box DB: 2200 mm. inner diameter of the ladle bottom 10: 3530 mm

(18) The melt stream M hits the impact area 10i (with CP1 being the central hitting point) in a conventional way but its speed is then slowed down on its way to pouring channel 16 by said diffusor box DB and especially by said step S, which at the same time redirects the melt stream M twice (FIG. 3: F, F′, F″).

(19) By this means the filler material FS is protected from being flushed away until the ladle is filled more or less completely and the pouring channel 16 opened in a conventional way.

(20) The filler material remains more or less intact and at its place even in case of a (conventional) gas treatment of the melt as the then rotating melt “overflows” said area of said diffusor box to a considerable extent with a considerably reduced speed. One of several gas purging plugs, installed in ladle bottom 10 is shown as GP. The distance between its central longitudinal axis and CP2 is 1020 mm.

(21) FIG. 3 shows a diffusor box DB arranged offset ladle wall 12, i.e. with a circumferentially extending borderline B and step S. It further includes an optional feature of a barrier shaped as a rib R in front of said step S and/or in front of the pouring channel 16 (seen in the flow direction F of the metal melt MS) to further reduce the melt speed. Insofar the said barrier is arranged across (perpendicular to) to a straight line between CP1 and CP2 being the direction of the melt on its way from impact area 10i to pouring channel 16, symbolized by arrows F, F′, F″. This barrier may be replaced by one or more protruding shapes, including: undulated surface sections, dams, prism or the like.