Metallurgical apparatus – Process – Plugging or tapping
Patent
1991-05-29
1992-08-11
Rosenberg, Peter D.
Metallurgical apparatus
Process
Plugging or tapping
C21B 712
Patent
active
051372622
DESCRIPTION:
BRIEF SUMMARY
When steel is being formed, the raw materials are fed into a heated vessel and the formed molten steel is ultimately poured out through a tap hole in a side wall as the vessel is tipped. It is highly desirable that the tap hole should be blocked off during the steel-making process for two main reasons. Firstly, this prevents the passage of air through the tap hole into the interior of the vessel during the forming of the steel, which helps to control the nature of the gas within the vessel during the forming process. Secondly, when the vessel is tipped to pour out the molten steel it is important to avoid the possibility that the slag floating on top of the steel should pass through the tap hole as the edge of the liquid first arrives at the tap hole.
Because of the conditions, particularly extremely high temperatures, existing in the area of the steel-making vessel, and the fact that the tap hole attains a very irregular shape with use, it is difficult to achieve blocking of the tap hole and it is an object of this invention to alleviate this particular problem.
Accordingly, the invention provides a tap hole blocking insert for a steel-making vessel comprising a former constructed from a material which is stable at low refractory temperatures, but which will melt at high refractory temperatures, and which is sufficiently flexible to bend when inserted into the tap hole, the former defining a centre cavity, open at the sides, between two end plates shaped to grip the sides of the interior of the tap hole, and an inlet passageway leading to the cavity for the injection of a settable material.
The low refractory temperatures referred to above are those which are likely to be experienced in the region of the tap hole during the steel-forming process and these typically might be within the region of 600.degree. to 700.degree. C.
The invention also extends to a method of blocking a tap hole, using an insert of this invention as hereinbefore defined, which comprises introducing the insert into the tap hole whilst the steel-making vessel is in the upright condition, and pressing the insert home as a tight fit within the tap hole, followed by injection of a material in wet form which will set at the low refractory temperatures to fill the space between the plates of the insert so as to block the tap hole, the set material being such that it will melt when subjected to the high refractory temperatures experienced during pouring of the molten steel.
In one embodiment the insert may have an axial support member connected between the plates but having holes in its side walls through which the settable material can pass. Alternatively the end plates may be held apart by spacer rods so as to define the centre cavity. These rods are ideally threaded so that the distance between the end plates may be varied as required and fixed by means of nuts.
In the preferred arrangement the edges of the plates of the insert are designed to flex as the insert is pressed into the tap hole so that the insert will adapt itself to the irregular shape of the tap hole. A particular preferred material for forming the end plates of the former is cardboard which has been found to have the necessary stability to remain in place at the high temperatures experienced for long enough to enable the settable material to be injected and set. For this purpose, therefore, cardboard is regarded as a material which is stable at low refractory temperatures. If desired, the cardboard sheets could be coated or impregnated with a flame-retardant solution. The use of cardboard is particularly suitable since it is flexible and thus will adapt to the irregular shape of the hole being blocked. Advantageously radially extending cuts will be formed in the outer edges of the end plates.
Tubing might be connected to the inlet passageway through which a settable material can be injected. Alternatively a cartridge of the settable material could be attached to or provide the inlet passageway, so that a plunger can be operated to inject the material within the cartridge
REFERENCES:
patent: 4471950 (1984-09-01), LaBate
patent: 4913404 (1990-04-01), Warman
Clempson Michael
Purchase Wynne
Goricon Metallurgical Services Limited
Rosenberg Peter D.
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