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 the upper surface and the lower surface, further comprising 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 defines a secondary upper surface of the ladle bottom, vertically below the upper surface, c) wherein the secondary upper surface has a minimum horizontal area $A_{\min }=\frac{n}{4}{\left(0.37r\right)}^2+0.3$ and a maximum horizontal area $A_{\max }=\frac{n}{4}{\left(0.8r\right)}^2+0.3$ 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 indentation, extending from said secondary upper surface towards the lower surface of the ladle bottom and defining a tertiary upper surface of the ladle bottom, vertically below the secondary upper surface, wherein e) the pouring channel runs through said diffusor box and indentation.

2. Ladle bottom according to claim 1, further comprising a) a recessed space, extending from said tertiary upper surface towards the lower surface of the ladle bottom and defining a quaternary upper surface of the ladle bottom, vertically below the tertiary upper surface, wherein b) the pouring channel runs as well through said recessed space.

3. Ladle bottom according to claim 1, wherein at least one of the following surfaces of the ladle bottom is inclined to the horizontal: upper surface, secondary upper surface, tertiary upper surface.

4. Ladle bottom according to claim 1, wherein at least one of the following surfaces of the ladle bottom has a three dimensional profile: upper surface, secondary upper surface, tertiary upper surface.

5. Ladle bottom according to claim 4, wherein the profile is at least one of the group comprising: ribs, knobs, prism, depression, channel.

6. Ladle bottom according to claim 1, wherein at least one of the following surfaces of the ladle bottom has a polygonal, circular or oval shape: secondary upper surface, tertiary upper surface.

7. Ladle bottom according to claim 1, wherein adjacent upper surfaces of the ladle bottom are dimensioned such that the upper surface being closer to the lower surface of the ladle bottom, has an overall area being <60% of the surface arranged on top.

8. Ladle bottom according to claim 1, wherein adjacent upper surfaces of the ladle bottom are vertically offset by 20 to 200 mm, thereby forming a step at least about part of their respective peripheries.

9. Ladle bottom according to claim 8, wherein the step extends along at least 50% of the periphery of the lower of said upper surfaces.

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 boxbeing 30 to 75% 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. Metallurgical ladle with a ladle bottom, the ladle bottom made of a refractory ceramic body with an upper surface, a lower surface and a pouring channel extending between the upper surface and the lower surface, further comprising 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 defines a secondary upper surface of the ladle bottom, vertically below the upper surface, c) wherein the secondary upper surface has a minimum horizontal area $A_{\min }=\frac{\pi }{4}{\left(0.37r\right)}^2+0.3$ and a maximum horizontal area $A_{\max }=\frac{\pi }{4}{\left(0.8r\right)}^2+0.3$ 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 indentation, extending from said secondary upper surface towards the lower surface of the ladle bottom and defining a tertiary upper surface of the ladle bottom, vertically below the secondary upper surface, wherein e) the pouring channel runs through said diffusor box and indentation.

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 with one single diffusor box in a longitudinal sectional view and a top view

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

(5) FIG. 4 the embodiment of FIG. 3 in a still more schematic cross sectional view

(6) FIG. 5 a further embodiment with one additional indentation in a view according to FIG. 4

(7) FIG. 6 a third embodiment with one additional indentation and one additional recessed space in a view according to FIG. 4

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

(9) 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.

(10) A metal stream 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 10o of ladle bottom 10.

(11) 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 10o to lower surface 10u.

(12) 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.

(13) 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.

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

(15) 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, periphery) B of said diffusor box DB. The upper surface section of diffusor box DB is referred to hereinafter as secondary upper surface 10od. The vertical part of said step S forms a right angle with respect to both adjacent sections of the upper bottom surface 10o and secondary upper surface 10od.

(16) The diffusor box DB has a mainly rectangular secondary upper surface 10od. A well nozzle 18 (German: Lochstein) is arranged in the bottom portion 10d of the diffusor box DB. The central through opening of said well nozzle 18 defines a lower part of pouring channel 16, while the diffusor box DB itself defines the widened upper part of pouring channel 16.

(17) An inner nozzle 20—known per se—is arranged downstream 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.

(18) The lower part of 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—.

(19) The dimensions of said diffusor box DB are as follows: height h of step S: 100 mm length: 1370 mm, width: 1085 mm diameter d 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 10o) and a central point CP2 along the secondary upper surface of the diffusor box DB: 2200 mm. inner diameter of the ladle bottom 10: 3530 mm

(20) 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 the lower section of 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″).

(21) 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.

(22) 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.

(23) FIG. 3 shows a diffusor box DB arranged offset ladle wall 12, i.e. with a circumferentially extending borderline/periphery 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 perpendicular to a straight line between CP 1 and CP 2 being the main direction of the melt on its way from impact area 10i to the lower part of the 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.

(24) FIG. 4 represents the embodiment of FIG. 3 in a more schematic way to improve illustration and comparison with the embodiments of FIGS. 5,6.

(25) The ladle bottom 10 of FIG. 5 differs from that of FIG. 4 by the following features:

(26) Secondary upper surface 10od (the bottom surface of diffusor box DB) includes a further deepened section, called indentation IN hereinafter.

(27) This indentation IN has a smaller horizontal cross section than diffusor box DB and extends at a distance to the peripheral steps S of diffusor box DB, thereby providing additional steps S2 and a tertiary upper surface 10oi.

(28) The lower section of pouring channel 16 now extends from said tertiary upper surface 10oi downwardly.

(29) In the embodiment of FIG. 6 the indentation IN is followed (in a downstream direction of metal flow F) by a recessed space RS, thereby providing a quaternary upper surface 10or, further steps S3 on 3 sides (the 4.sup.th being flush with adjacent step S2), and a horizontal cross section smaller than that of indentation IN. While the upper section of pouring channel 16 being defined by the hollow spaces of diffusor box DB, indentation IN and recessed space RS its lower part now extends from recessed space RS downwardly.

(30) In this embodiment tertiary upper surface 10oi is inclined by 4° to the horizontal.

(31) All embodiments are characterized by several deviations for the metal stream on its way to the lower part of pouring channel 16, provided by said deepened sections (diffusor box DB, indentation IN, recessed space RD respectively) and their corresponding steps S, S2,S3, thereby slowing down the melt speed and allowing any remaining melt to leave the ladle almost completely.