LU500076B1 - Gas purging plug for a metallurgical container - Google Patents

Gas purging plug for a metallurgical container Download PDF

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Publication number
LU500076B1
LU500076B1 LU500076A LU500076A LU500076B1 LU 500076 B1 LU500076 B1 LU 500076B1 LU 500076 A LU500076 A LU 500076A LU 500076 A LU500076 A LU 500076A LU 500076 B1 LU500076 B1 LU 500076B1
Authority
LU
Luxembourg
Prior art keywords
casing
gas purging
block
purging block
gas
Prior art date
Application number
LU500076A
Other languages
French (fr)
Inventor
Eric Hanse
Alessandro Valeri
Original Assignee
Exus Refractories Spa
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Exus Refractories Spa filed Critical Exus Refractories Spa
Priority to LU500076A priority Critical patent/LU500076B1/en
Application granted granted Critical
Publication of LU500076B1 publication Critical patent/LU500076B1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
    • B22D1/002—Treatment with gases
    • B22D1/005—Injection assemblies therefor
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/34—Blowing through the bath
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/35—Blowing from above and through the bath
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/42—Constructional features of converters
    • C21C5/46—Details or accessories
    • C21C5/4606—Lances or injectors
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/42—Constructional features of converters
    • C21C5/46—Details or accessories
    • C21C5/48—Bottoms or tuyéres of converters
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/072—Treatment with gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D27/00—Stirring devices for molten material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/16—Introducing a fluid jet or current into the charge
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D27/00—Stirring devices for molten material
    • F27D2027/002—Gas stirring

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Furnace Charging Or Discharging (AREA)

Abstract

This gas purging block (2) for a metallurgical container comprises: - a body (4) of refractory material delimited by an upper end (6) and a lower end (8), said upper end (6) is adapted to be in contact with molten metals, and said lower end (8) is arranged to receive a gas flow, wherein at least one flow channel (10) is arranged between the two ends (6, 8); - at least one sheet of heat-resistant material encapsulating a lower portion of the flow channel (10) extending from the lower end (6) and forming a casing (18) inside the body (4), said casing (18) does not extend to the upper end (8); and - a bottom plate (20) attached to the casing (18).

Description

Gas purging plug for a metallurgical container The invention relates to a gas purging block for a metallurgical container.
The invention also relates to a method for manufacturing the gas purging block.
In addition, the invention relates to the use of the gas purging block in a metallurgical container.
It is well-known in the field of metallurgical processes, for example in steelmaking, to regularly, or even continuously, mix the molten metal within a metallurgical container in order to ensure uniform temperature and homogenization of the molten metal.
This favours the reactions of the molten metal with additives mixed into the metallurgical container and facilitates the chemical balance with the slag.
In this regard, one approach consists in injecting an inert gas at a high pressure through a gas purging device located at the bottom of the metallurgical container, for example of a ladle.
In general, the purging device is manufactured with the following steps.
First a purging plug is manufactured by casting a green refractory composition into a metal casing.
A drying step of the green refractory composition is required in order to harden it into a permeable refractory core.
After the drying step, the purging plug is, for example coated with a refractory mortar.
Then the plug is inserted into a refractory concrete block (named “well block”) with a channel arranged to accommodate the purging plug.
After another drying step, the purging device is formed.
Although the metal casing ensures the integrity of the purging plug during its insertion or extraction into or from the well block and a gas-tight seal between the purging plug and the well block, it has been observed that the metal casing may be separated from the rest of the refractory part during the drying step of the purging plug, due to the different thermal expansion of the metal casing and of the refractory material.
Such a thermal expansion may create unwanted bypass channels for the injected gas, in addition to a main flow channel, through which the inert gas can pass.
Under these circumstances, the blowing efficiency in the metallurgical container may be reduced.
Furthermore, the bypass channel is a potential path for the molten metal infiltration into the purging plug or the refractory block.
When the purging plug is eroded after prolonged contact with the molten metals, the replacement of the used purging plug by a new purging plug is required.
However, it is extremely complex to fit exactly the new purging plug in a used well block.
As a result, the molten metal can penetrate in gaps created between the outer wall of the new purging plug and the used well block.
Steel mills may envision replacing both the purging plug and the well block to ensure maximal safety, but this comes with a high cost.
-2- LU500076 The main object of the invention is therefore to propose a gas purging device preventing the above-mentioned problems. To that end, the invention provides a gas purging block for a metallurgical container comprising: - a body of refractory material delimited by an upper end and a lower end, said upper end is adapted to be in contact with molten metals, and said lower end is arranged to receive a gas flow, wherein at least one flow channel is arranged between the two ends; - at least one sheet of heat-resistant material encapsulating a lower portion of the flow channel extending from the lower end and forming a casing inside the body, said casing does not extend to the upper end; and - a bottom plate attached to the casing.
Thus, the purging block forms a single piece, contrary to the plug and the well block of the prior art, and this allows the safe replacement of a used purging block by a new one without creating any bypass channels or gaps, preferably at the upper portion of the channel, in particular during the drying step of the refractory material forming the body. This prevents the leakage of gas or the infiltration of molten metal alloys into the purging block. In addition, the presence of the bottom plate forms a first barrier in case of a leakage of molten metals.
Furthermore, the absence of the casing at the upper end reduces the amount of the heat-resistant material used to manufacture the casing and represents a cost-effective and ecological solution.
The gas purging block according to the invention may comprise one or several of the following features taken alone or in combination.
The height of the casing is preferably less than 90% of the height of the purging block, preferably less than 75%, and in particular about 50% of the height of the purging block.
These percentages correspond to the maximum authorized erosion depth of the body measured from the upper end. In other words, the height of the casing is lower than the difference between the height of the gas purging block and the maximum authorized erosion depth.
The casing is made in a single piece.
Thus, the casing remains robust despite the thermal expansion of the refractory material during the drying step.
The heat-resistant material is chosen among the group consisting of graphite, glass, steel, steel alloys, stainless steel and heat resistant polymers.
The heat resistant material forming the casing resists up to a temperature higher than 400°C, preferably higher than 600°C.
-3- LU500076 The refractory material forming the body is chosen among the group consisting of alumina, magnesia, zirconia, silica, lime and chrome oxide or a mixture thereof. The gas purging block further comprises a safety closing system arranged into the lower end of the body. Thus, this reinforces the safety of the purging block against a molten metal leakage. The invention also relates to a method for manufacturing a gas purging block, comprising the following steps: - providing a permeability precursor into a mold; - arranging a casing surrounding one end of the permeability precursor such that the height of the casing is lower than the height of the permeability precursor; - introducing a refractory material into the mold; - drying the refractory material, and - attaching a bottom plate to the casing and obtaining a purging block. Thus, a one-piece gas purging block made of a single type of refractory material is formed, without creating any bypass channels or gaps. This represents a fast, cost- effective manufacturing method. The permeability precursor already comprising a flow channel may stay within the purging block. If necessary, the permeability precursor can be removed during the drying step in order to create a flow channel formed by the refractory material alone. Furthermore, the presence of the bottom plate forms a first barrier in case of a leakage of molten metals. The method may further comprise the step of coupling a safety closing system with the casing. The invention also relates to a use of gas purging block according to the invention for injecting a gas in a metallurgical container.
Brief description of the figures Other features and advantages would appear by reading the following description, given as an illustrative and non-restrictive example, and with the annexed drawings in which: - figure 1 illustrates an exploded, three-dimensional view of a gas purging block according to a particular embodiment of the invention: - figure 2 illustrates a longitudinal section view of the gas purging block of figure 1; and - figure 3 illustrates a top view of the gas purging block of figure 1.
Detailed description
-4- LU500076 Figure 1 represents a gas purging block 2 for a metallurgical container according to an embodiment of the invention. The gas purging block 2 is configured to be insertable into a wall generally located at the bottom of a metallurgical container (not represented) to permit the injection of inert gas into the metallurgical container. Such inert gas injection permits to mix molten metals contained in the metallurgical container in order to ensure uniform temperature and homogenization of the molten metals. Preferably, the gas purging block 2 is arranged so that it can be removed and replaced from the outside of the metallurgical container.
The gas purging block 2 comprises a body 4 made of a refractory material. The refractory material is chosen among the group consisting of alumina, magnesia, zirconia, silica, lime and chrome oxide, or a mixture comprising at least one of the materials of said group. The body 4 has a shape of a revolution cylinder, an axis 5 of said cylinder sensibly coinciding with the vertical axis when the gas purging block 2 is inserted into a wall of the metallurgical container. With respect to this configuration of the gas purging block 2, the body 4 is delimited by an upper end 6, adapted to be in contact with the molten metals within the metallurgical container, and a lower end 8, not exposed to the molten metals contained in the metallurgical container.
Referring to figure 2, the body 4 comprises a flow channel 10 arranged between the lower end 8 and the upper end 6 such that the lower and upper ends are in fluidic communication. At the lower end 8, the flow channel 10 leads to a central orifice. At the upper end 6, the flow channel 10 leads to a plurality of holes arranged regularly over the surface of the upper end surface. Now referring to figure 3, the holes are formed by radial slits 12 located closer to the center of the upper end surface than the circumference of the upper end surface. There are twenty slits 12 equally spaced, the slits 12 having a width of 25 mm and a thickness comprised between 0,20 and 0,25 mm. Naturally, there could be a different number of slits, and they can be arranged in a different configuration, for example depending on the geometry of the metallurgical container.
The gas purging block 2 comprises two hooks 14 rigidly attached to the upper end 6 of the body 4. The hooks 14 are provided to permit an easier manipulation of the gas purging block 2, for example with machinery for moving the gas purging block 2 and connecting it to the metallurgical container.
The gas purging block 2 comprises a pipe 16 comprising a first end configured to be connected to a source of inert gas (not represented) and a second end configured to be connected through the central orifice of the flow channel 10 located at the lower end 8 of the body 4. The inert gas provided by the source can thus flow through the pipe 16 then the flow channel 10 within the body 4 and exit into the metallurgical container from the slits 12.
-5- LU500076 The gas purging block 2 comprises a sheet of heat-resistant material encapsulating a lower portion of the flow channel 10 extending from the lower end 8 and forming a casing 18 inside the body 4. The heat-resistant material is chosen among the group consisting of graphite, glass, steel, steel alloys, stainless steel and heat resistant polymers, or a mixture comprising at least one of the materials of said group. More generally, the heat- resistant material forming the casing 18 is chosen such that the casing resists up to a temperature higher than 400°C, preferably higher than 600°C. In other words, the heat- resistant material forming the casing 18 is chosen such that the casing 18 remains solid at temperatures equal to or below the aforementioned temperatures. The casing 18 is made in a single piece. The casing 18 does not extend to the upper end 6 of the body 4. Specifically, the height of the casing 18 is less than 90% of the height of the purging block, preferably less than 75%, and in particular less than 50% of the height of the gas purging block 2. In the present embodiment, the height of the casing 18 is about 15% of the height of the gas purging block 2.
The gas purging block 2 comprises a bottom plate 20 attached to the casing 18, for example welded to the casing 18 or any other type of gas-tight attachment. The bottom plate 20 is here made of the same material as the casing 18. The bottom plate 20 comprises a central aperture equipped with means for securing the second end of the pipe 16.
The gas purging block 2 comprises a safety closing system 22 arranged into the lower end 8 of the body 4. The safety closing system 22 comprises a copper wire embedded in the body 4. Preferably, the safety closing system 22 is arranged so that it can be removed and replaced from the outside of the metallurgical container.
A method for manufacturing the gas purging block 2 according to the invention will now be presented.
A permeability precursor is first provided into a mold. The permeability precursor will be used to form the flow channel 10 in the body 4. To form all the parts of the flow channel leading to the slits 12, the permeability precursor may comprise capillary nets, plastic strips, etc.
The safety closing system 22 is coupled to the casing 18, which is then placed in the mold around one end of the permeability precursor such that the height of the casing 18 is lower than the height of the permeability precursor.
The refractory material is casted into the mold then dried. The drying may be realized at room temperature, which is cost-effective. Alternatively, the refractory material may be fired or cured to speed up the drying. Depending on the material of the capillary nets or plastic strips they may burn during the firing or the curing, which make it easier to remove the capillary nets or plastic strips after the molding.
-6- LU500076 After the refractory material has dried, the block is removed from the mold, and the bottom plate is attached to the lower end of the block in order to obtain the gas purging block 2 which can then be used for injecting inert gas in the metallurgical container.
The here-above embodiments are illustrative and not restrictive embodiments.
Obviously, many modifications and variations of the present invention are possible in the light of the above teachings without deviating from its inventive concept.
It has therefore to be understood that the invention may be practiced otherwise that as specifically described.
According to a variant, the body can have a rectangular cuboid shape.
More generally, the body can have any shape to conform to the shape of the aperture in the metallurgical container configured to receive the gas purging block.
The gas purging block may be equipped with a wear detection unit configured to emit a warning signal when the body is worn further than a predetermined threshold.
At this stage, it would be recommended to withdraw the gas purging block from the metallurgical container and replace it with a new one.
Numerical references 2: gas purging block 4: body 5: axis 6: upper end 8: lower end 10: flow channel 12: slit 14: hook 16: pipe 18: casing 20: bottom plate 22: safety closing system

Claims (10)

-7- LU500076 Claims
1. Gas purging block (2) for a metallurgical container comprising: - a body (4) of refractory material delimited by an upper end (6) and a lower end (8), said upper end (6) is adapted to be in contact with molten metals, and said lower end (8) is arranged to receive a gas flow, wherein at least one flow channel (10) is arranged between the two ends (6, 8); - at least one sheet of heat-resistant material encapsulating a lower portion of the flow channel (10) extending from the lower end (6) and forming a casing (18) inside the body (4), said casing (18) does not extend to the upper end (8); and - a bottom plate (20) attached to the casing (18).
2. Gas purging block (2) according to claim 1, wherein the height of the casing (18) is preferably less than 90% of the height of the gas purging block (2), preferably less than 75%, and in particular less than 50% of the height of the gas purging block (2).
3. Gas purging block (2) according to claim 1 or 2, wherein the casing (18) is made in a single piece.
4. Gas purging block (2) according to any one of the preceding claims, wherein the heat-resistant material is chosen among the group consisting of graphite, glass, steel, steel alloys, stainless steel and heat resistant polymers.
5. Gas purging block (2) according to any one of the preceding claims, wherein the heat-resistant material forming the casing (18) resists up to a temperature higher than 400°C, preferably higher than 600°C.
6. Gas purging block (2) according to any one of the preceding claims, wherein the refractory material forming the body (4) is chosen among the group consisting of alumina, magnesia, zirconia, silica, lime and chrome oxide or a mixture thereof.
7. Gas purging block (2) according to any one of the preceding claims, further comprising a safety closing system (22) arranged into the lower end of the body (4).
8. Method for manufacturing a gas purging block (2), comprising the following steps: - providing a permeability precursor into a mold;
-8- LU500076 - arranging a casing (18) surrounding one end of the permeability precursor such that the height of the casing (18) is lower than the height of the permeability precursor; - introducing a refractory material into the mold; - drying the refractory material, and - attaching a bottom plate (20) to the casing (18) and obtaining a gas purging block (2).
9. Method according to claim 8, further comprising the step of coupling a safety closing system (22) with the casing (18).
10. Use of a gas purging block (2) according to any one of the claims 1 to 7 for injecting a gas in a metallurgical container.
LU500076A 2021-04-23 2021-04-23 Gas purging plug for a metallurgical container LU500076B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
LU500076A LU500076B1 (en) 2021-04-23 2021-04-23 Gas purging plug for a metallurgical container

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
LU500076A LU500076B1 (en) 2021-04-23 2021-04-23 Gas purging plug for a metallurgical container

Publications (1)

Publication Number Publication Date
LU500076B1 true LU500076B1 (en) 2022-10-24

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Family Applications (1)

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LU500076A LU500076B1 (en) 2021-04-23 2021-04-23 Gas purging plug for a metallurgical container

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Country Link
LU (1) LU500076B1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4647020A (en) * 1983-12-12 1987-03-03 Arbed S.A. Gas-permeable element of a refractory material
EP2812137A1 (en) * 2012-02-07 2014-12-17 Vesuvius Crucible Company Ga purging plus comprising wear indicator
US20160290722A1 (en) * 2014-01-09 2016-10-06 Refractory Intellectual Property Gmbh & Co. Kg Gas purging element and associated gas connection element
US20190118247A1 (en) * 2017-10-19 2019-04-25 Refractory Intellectual Property Gmbh & Co. Kg Refractory ceramic gas purging element

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4647020A (en) * 1983-12-12 1987-03-03 Arbed S.A. Gas-permeable element of a refractory material
EP2812137A1 (en) * 2012-02-07 2014-12-17 Vesuvius Crucible Company Ga purging plus comprising wear indicator
US20160290722A1 (en) * 2014-01-09 2016-10-06 Refractory Intellectual Property Gmbh & Co. Kg Gas purging element and associated gas connection element
US20190118247A1 (en) * 2017-10-19 2019-04-25 Refractory Intellectual Property Gmbh & Co. Kg Refractory ceramic gas purging element

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Effective date: 20221024