JPS6014811B2 - Method of protecting gas blowing surface of porous plug and its protective material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for protecting a gas blowing surface for blowing a gas such as argon or nitrogen into molten steel in a molten metal container such as a ladle or a dish refining furnace, and a protective material therefor. .

Recently, in order to improve the quality of steel, gas is injected into molten steel to desulfurize and
Treatments such as deoxidation, dephosphorization, descaling, and separation of nonmetallic inclusions are frequently used.

Along with this, many research results on the materials and shapes of porous plugs have been published, and materials such as magnesia, spinel, high alumina, etc., with limited particle sizes, and shapes such as two-layer types are known. Repair methods have also been exemplified as a measure to extend the life of porous plugs, and one example is Tokubatsu 122621 of 1983. In this known example, a so-called wet repair material is protected or repaired by stamping or pouring, and the porous plug is protected by adhering it to some extent after melting or before use.

However, this method has the disadvantage that the blowout amount varies widely depending on the stamped or poured protective repair material compared to the well-controlled blowout amount of a porous plug. In addition, when the protective repair material applied to the top surface of the porous plug is damaged, it can be protected or repaired by removing the protective repair material after discharging the molten steel, and then pouring and applying a new protective repair material. However, the disadvantage is that this removal process is extremely complicated. The present invention aims to prevent these drawbacks and provide an excellent method or material for protecting porous plugs. Taking a ladle as an example of how to use it, the ladle that has received and discharged steel undergoes various inspections and maintenance in order to receive the next steel. Confirmation tests will be conducted and the steel will be used for the next round of receiving steel.
However, even though porous plugs were found to be safe to use after these confirmation tests, accidents that made it impossible to blow were occurring at a rate of two to three times a month. After this confirmation test, the present invention is to drop a protective material consisting of refractory grains and solid pitch whose particle size has been adjusted onto the porous plug that has been found to pose no problem in use, and to cover the gas blowing surface of the porous plug. This protective material uses magnesia whose particle size is adjusted to 2 to 0.2 skin.
One or two of spinel, alumina, mullite, and zircon
It consists of 3 to 7 parts by weight of solid pitch added to 3 parts by weight of the refractory material 10 of a grade or higher.

The method of the present invention applies dry protective material to 0.5 to 1.0% after preparing the pot.
5K9 Tachibana is simply used or directly dropped into the damaged part of the porous plug and layered, and the work is very simple and there is no danger at all. Although this protective material was present when the molten steel was received, it was thought that it would have been blown away by the pressure during gas injection, and no confirmation of the protective material could be obtained after the discharge.

However, by using this method, there will be no accidents where gas cannot be blown out, and furthermore, conventionally, due to fear of this accident,
The porous plug was replaced after ~5 charges, but by adopting this method, the number of uses increased dramatically to 10~15 charges.

The protective material is preferably a refractory material whose grain size is adjusted to 2 to 0.2, such as alumina, mullite, spinel, or magnesia, which is the same or similar material to porous plugs. The reaction with the porous plug causes formation of crystals, which is undesirable. Also, if coarse grains are used on two or more sides, the number of voids increases, and the molten steel and the porous plug body contact each other, causing metal adhesion to the porous plug, which is undesirable. Furthermore, since there is almost no age pay with these refractory materials alone, the refractory materials 100
It is preferable to add 3 to 7 parts by weight of solid pitch per part by weight. If it is less than 3 parts by weight, it is insufficient to contribute to competitive sintering, and if it is less than 7 parts by weight, sintering will be severe and will obstruct blowing from the porous plug, which is not preferable.

In an example of implementing the present invention using a $150 ladle, the porous plug is made of mullite, and after receiving one charge of molten steel in the ladle, the ladle is heated to 5% mullite on the 3-1 side at a ladle repair shop. , 2 sails 1.0 kg of the protective material with a blending ratio of 95% solid pitch + 4% was placed onto the porous plug using a bucket.

Claims (1)

[Scope of Claims] 1. A method for protecting the gas blowing surface of a porous plug, which comprises placing refractory granules on the damaged gas blowing surface of a porous plug for blowing gas installed in a molten metal container. 2. The porous plug is made of the same or similar material.
A protective material for the gas blowing surface of a porous plug, which is made by adding 3 to 7 parts by weight of solid pitch to 100 parts by weight of one or more refractory materials of magnesia, spinel, alumina, and mullite whose particle size is adjusted to 0.2 mm.