LU86816A1 - DEVICE FOR DRAINING METALLURGICAL CONTAINERS - Google Patents

Description

A 824

8 “fi ö 1 y GRAND-DUCHY OF LUXEMBOURG

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of jv. \ .... £ ^ Λ353 CyÈlI ^ Dear Minister gY | süf | Economy and the Middle Classes

Title issued ......................................... Intellectual Property Service

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Invention Patent Application df> s'I t l I. Request ...... ARBEDS. Have)

Avenue de la Liberté, L - 2930 LÜÏŒMBÔÜRG

....... represented by Messrs NEYEN René, engineer __________________________________ (2) LEÏTZ Paul, engineer deposits (nt) ce. „. 1.9 .... March ..... 1.90.0 ._ ^ uatr.e. -vingtr.s.ep.t .......................................... ................... (3) at., IS ... 3o ........ hours, at the Ministry of the Economy and the Middle Classes , in Luxembourg: 1. this request for obtaining a patent for an invention concerning: ............................ .................................................. .................................................. .................................................. .................................................. .......................................... (4)

Device for emptying metallurgical vessels 2. the delegation of power, dated ..L.UX.emb.0..ur..g .................... ..... on 1.9 ..... March ..... 1.9..8..7 .___________ 3. description in language ....... fr.anÇ.ai, S .. e ............................. of the invention in two copies; 4 ..... 1 ....................... drawing boards, in two copies; 5. the receipt of the fees paid to the Luxembourg Registration Office on March 19, 1987 ......................... .................................................. .................................................. ...............__.................................. .

declares (s) assuming responsibility for this declaration, that the inventor (s) is (are): ....................... ...... (5) ...... Mons.i.Rux ._. MEYER .... Ir.an.Qi5 ................. .................................................. .................................................. .............................................

26 rue Pasteur _ _ _ __ _ 4642 DÏFFERDÂNGÈ ___________________________________________________________________________________________________________________________________________________________________________________ claim) for the above patent application the priority of one (s) application (s) of (6) ................ .................................................. .......................... filed in (7) ................ .................................................. ...........................................

on ------------------------------------------ (8) in the name of__________________________________________________________________________________________________________________________________________________________________________________________________________________________ ( 9) elect (elect) for him / her and, if designated, for his / her representative, in Luxembourg________________ ..ARBED ..... S .., A, ..., .......... ., C.as.e ..... P..osta.le ........ I.8.Û.2., ...... L ..... =. ..... 29.3.0 ...... LUXEMBOURG .__________ (10) requests (s) the grant of a patent for the invention for the subject described and represented in the stfsjiientioimées annexes, - with adjournment of this issued at _________________________. 1.8 ______________ months. (11)

_______________________ LEIT2 ^ Paul Π. Deposit Minutes

The above patent application has been filed with the Mini Stere de l'Economie et des Classes Moyennes, Intellectual Property Service in Luxembourg, on:

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A 824

Applicant's patent application: ARBED S.A.

Avenue de la Liberté L - 2930 LUXEMBOURG

Device for emptying metallurgical vessels "- 1 -

Device for emptying metallurgical vessels.

The present invention relates to a device for emptying metallurgical vessels, in particular steelworks converters, containing metal and slag.

Towards the end of the pouring of metal, particularly steel, into a transport or processing container, a certain amount of slag passes through the tap hole. This results in a risk of rephosphorization of the steel. On the other hand, due to the high activity of oxygen in the slag, the metallurgical treatment of quenched and semi-quenched steels is then difficult to perform. In addition, the desulphurization of the steel becomes critical. Also efforts have been made for a long time to avoid the entrainment of slag during the emptying of metallurgical vessels and various devices which can be used for this purpose have already been developed. The best known of these devices are the shutter valve, the drawer closure and the massive float, the cross section of which is wider than that of the flow orifice and which swims above the mouth of the casting. These floats 20 have a density between that of the slag and that of the metal and have the function of closing the tap hole, when practically all the metal has flowed.

These devices undoubtedly make it possible to reduce the flow of slag in the pocket, but are not suitable for slowing down the quantity of slag entrained by the vortex, known as a vortex, which forms above the taphole and whose central hollow can cross the depth of the bath. It has already been proposed to reduce the effect of this vortex - 2 - by blowing a bubbling gas into the metal bath, either through the tap hole, or in the immediate vicinity of the latter. Unfortunately, the nozzles used for insufflating require, in order to avoid their obstruction, large quantities of 5 gases, not only during the draining, but also during the campaign. On the other hand, the nozzles coming into contact with the slag and the liquid metal, have lifetimes significantly shorter than those of the surrounding coating.

10 It is also known to have gas permeable elements in the vicinity of the taphole, comprising elongated segments having a rectangular section and provided on the cold side with a gas distribution chamber. These permeable elements are preferably two or four in number and located around the taphole at a distance of about 0.5 m from the axis. The continuous bubbling of gas on the surface of the metal expels the slag, but only above the permeable elements and the slag may nevertheless reach the taphole by flowing between the slag-free areas above the permeable elements .

20

The object of the present invention is to remedy these drawbacks, and to effectively limit the quantities of slag entrained by the vortex which forms above the taphole.

25 This object is achieved by the device according to the invention, as characterized in claim 1. Preferential alternative embodiments are described in the dependent claims.

The bubbling agent is usefully a neutral gas such as argon, nitrogen or possibly carbon dioxide. The gases used serve at the same time as washing gases favoring the ascent of the inclusions of impurities, suspended in the metal, towards the surface. The tap hole and the segments are directly adjacent, the space is tolerable and the assembly is easy; moreover, the gases having a cooling effect on the walls of the taphole, their wear is delayed.

- 3 - The invention is explained in more detail using the description of schematic drawings which show, without limitation, possible embodiments.

5 Fig. 1 schematically shows a longitudinal section through a part of a converter having a taphole according to the invention, FIG. 2 a variant of a tap hole according to the invention and FIGS. 3 and 4, cross sections through tap holes.

We distinguish in Fig.l a tap hole 1 housed in the coating 2 of a converter in the drain position. To prevent premature slag and metal leakage during tipping, the tap hole 1 was previously closed with a wooden plug. After tilting, this plug burns quickly and is pushed out of the tap hole 1, freeing the passage to steel 3. Eight elements permeable to a bubbling agent are located around the tap hole 1. It is essential that a first series of permeable elements 20 ables 4 is adjacent to the stone comprising the hole which gives way to the steel. There is also shown a second series of permeable elements 5 which can be separated by a few tens of centimeters from the first series; the optimum separation distance, the number and size of these elements, their minimum degree of permeability, etc. are determined for each converter by routine testing.

The various permeable elements are each provided on the cold side with a distribution chamber (not shown) from which a conduit 7 leads leading to valves for adjusting the gas flow rate. One can provide an individual supply of each permeable element but usually the elements of the first series are supplied in parallel; it is the same for those of the second series. For reasons of assembly economy, it is obviously possible to supply all the permeable elements in parallel. It is however advantageous to have at its disposal possibilities for differential adjustment of the flow rates, and this especially towards the end of the casting, when the slag layer becomes thicker. At this time, the permeable exterior elements 5 require a high gas flow rate to discharge the slag layer.

5 Note that to compensate for a possible breakthrough, the bodies of the permeable elements 4.5 do not cross the entire thickness of the coating 2; for the same reason the conduits 7 have baffles (not shown) capable of ensuring the freezing of the steel.

10 At the start of the emptying, when the risks of vortex formation are reduced, the total quantity of gas injected is average. It is mainly done by the elements 4, adjacent to the taphole, so as to have a given quantity of gas entrained by the flow of metal flowing from the container; it is this gas which influences the wear profile of the inlet and the wall of the tap hole. The remaining quantity of gas leaving the elements forms a curtain 8 of bubbling agent around the hole and rises to the surface where it creates a circular area 9. This range is free of slag, so that the steel can flow without being loaded with inclusions.

20

Towards the end of the pouring process, when the risks of forming a vortex increase, the quantity of gas injected by the elements adjacent to the taphole is increased to the maximum. Likewise the amount of gas passing through the elements 5 is increased, minus 25 to counteract the creation of the vortex, but rather to repel the slag above the hole.

O

During the campaign, a gas flow of ca. two rev / hour ensures the permeability of a refractory element. At the time of the changeover

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30 the flow is increased up to ten m / hour to reach

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around twenty mJ / hour towards the end of the casting. Note that exaggerated gas flows towards the end of the casting cause metal and slag splashes which are not favorable for a clean casting. Likewise, it is not advisable to inject exaggerated amounts of gas into the bath, to avoid significant cooling of the metal.

- 5 -

In Eig. 2 shows a variant, in which the second series of permeable elements 25 is separated by a minimum distance from the first series 4. Such an execution may be imposed by constraints coming from the construction details of the coating 2. It must also be chosen, when the permeability of the refractory elements 4 is not sufficient to effectively counteract the creation of the vortex.

Fig. 3 shows details of a tap hole 1 surrounded by a first series of four permeable elements 4. Each of the four permeable elements is constituted by two neighboring refractory material segments 31, surrounded by a metal box 32. On the cold side of the element, a distribution chamber (not visible) is welded to the walls of this box. The gas passage takes place mainly at the interface of the segments. One of the adjacent faces may have a profiling, such as lines or grooves. It is also possible to insert metal plates between the segments of the material. When considering injecting into the metal a gas capable of decomposing the material of the segments, it is necessary to surround the latter on all sides with a protective metallic envelope or else to accommodate metal channels between the segments, such as explained for example in patent LU 85.131. To limit the passage of uncontrolled gas at the interface of the refractory elements and the box, it is generally advisable to mount the elements 25 in the box using refractory concrete.

Fig. 4 shows a variant in which the tap hole is surrounded by a single permeable element 44, having the shape of a hollow truncated cone.

Claims (5)

1. Device for emptying metallurgical vessels containing metal and slag, which device consists of a taphole adjacent to means for blowing a bubbling agent into the bath, characterized in that these means are immediately adjacent to the poured and consist of at least four permeable refractory elements, comprising at least one elongated segment of refractory material, preferably having a rectangular section, this refractory element being provided on its cold side with gas distribution means, which are connected by through a conduit to a source of bubbling agent. 2. Device according to claim 1, characterized in that it comprises a first series of four permeable refractory elements, adjacent to the taphole, as well as four additional permeable refractory elements, slightly distant from the first series, preferably of a fifteen centimeters. 20 3. Device according to claim 1, characterized in that the distribution means are constituted by a chamber in the extension of the metal box which surrounds the segments of refractory material. 25 4. Device according to claim 1, characterized in that metal channels, guiding the gas, are housed in the refractory material. 5. Device according to one of claims 1-4, characterized in that the source of bubbling agent is a source of argon, nitrogen or carbon dioxide.