Refining ladles need to know this when choosing breathable bricks
author: Archie
2025-05-09
The main functions of ladle breathable bricks are as follows:
(1) The uniform distribution of steel temperature in the ladle can be adjusted to achieve the optimum casting temperature for the existing process.
(2)The alloy and deoxidiser in the ladle can be evenly distributed by blowing and stirring.
(3) Non-metallic inclusions in the molten steel can be brought into the slag to meet the required cleanliness of the molten steel.
In order to achieve the above functions, it is necessary to blow the inert gas used in refining into the ladle through the permeable brick, on the contact surface of the permeable brick and steel, i.e., the working surface of the permeable brick, a large number of bubbles blown out under sufficient pressure to form a gas jet beam, stirring the steel in the whole ladle, prompting the flow of steel to homogenise the temperature and composition of the ladle, and at the same time, the constantly ejected bubbles will bring the non-metallic inclusions in the steel into the slag by the effect of the interface. At the same time, the continuously ejected bubbles will bring the non-metallic inclusions in the steel into the slag under the interfacial effect, so as to achieve the purpose of clean steel.
(2)The alloy and deoxidiser in the ladle can be evenly distributed by blowing and stirring.
(3) Non-metallic inclusions in the molten steel can be brought into the slag to meet the required cleanliness of the molten steel.
In order to achieve the above functions, it is necessary to blow the inert gas used in refining into the ladle through the permeable brick, on the contact surface of the permeable brick and steel, i.e., the working surface of the permeable brick, a large number of bubbles blown out under sufficient pressure to form a gas jet beam, stirring the steel in the whole ladle, prompting the flow of steel to homogenise the temperature and composition of the ladle, and at the same time, the constantly ejected bubbles will bring the non-metallic inclusions in the steel into the slag by the effect of the interface. At the same time, the continuously ejected bubbles will bring the non-metallic inclusions in the steel into the slag under the interfacial effect, so as to achieve the purpose of clean steel.
To meet the above metallurgical functions, breathable bricks must have the following main properties:
(1) Good air permeability. Gas permeability is one of the important parameters to measure the quality of gas permeable brick. Studies have shown that: the stirring energy of steel and blowing gas flow is directly proportional to; stirring energy directly affects the stirring efficiency of steel, only enough stirring energy to make the steel get good stirring effect. When the amount of argon blowing a certain amount of argon, blowing out the more argon bubbles, the more favourable to the degassing and mixing of steel.
(2) High temperature erosion resistance. Refining ladle in terms of temperature and time are very strict requirements, the highest temperature often reaches more than 1750 ℃, refining time sometimes reaches tens of minutes. During the refining operation, the slag alkalinity has a great impact on the life of the permeable brick. Therefore, permeable bricks are subject to erosion by the alkaline slag which is highly permeable at high temperatures, and destruction is rapid.
(2) High temperature erosion resistance. Refining ladle in terms of temperature and time are very strict requirements, the highest temperature often reaches more than 1750 ℃, refining time sometimes reaches tens of minutes. During the refining operation, the slag alkalinity has a great impact on the life of the permeable brick. Therefore, permeable bricks are subject to erosion by the alkaline slag which is highly permeable at high temperatures, and destruction is rapid.
(3) High temperature wear resistance. Refining ladle bottom blowing argon, due to the bottom blowing argon, steel in the ladle flow speed is very fast, steel on the furnace lining materials and the bottom of the permeable bricks and seat bricks of the scouring abrasion significantly increased. Ladle thermal repair, in order to remove the residual steel and residue on the surface of the permeable brick, restore the permeable brick permeability function, the need for the permeable brick surface oxygen blowing cleaning, so that the surface of the permeable brick adhering to the steel slag melting; at the same time to the permeable brick blowing blowing gas, blowing away the molten slag. In the cleaning process, the permeable brick is subject to high-speed gas flow scouring effect, so the permeable brick is required to have good high-temperature wear resistance.
(4) Good thermal shock resistance. Due to the intermittent operation of the ladle, the ladle poured into the molten steel, the end of the breathable brick by the role of high temperature molten steel, the temperature rises steeply, blowing argon, cooled by the cold airflow, the material produced a large internal thermal stress. At the same time, the ladle ladle injection of molten steel, but also produces a large temperature change, so the use of breathable bricks is very harsh conditions, very easy to produce thermal spalling and structural spalling.
(5) Requirements for easy installation, safe and reliable. Breathable brick is installed in the bottom of the ladle seat brick inside, the working conditions are extremely harsh, the life of the ladle breathable brick can not be synchronised with the life of the entire ladle, so the need to replace the breathable brick. Therefore, the installation operation is simple, safe and reliable, to avoid the occurrence of steel seepage and leakage.
(4) Good thermal shock resistance. Due to the intermittent operation of the ladle, the ladle poured into the molten steel, the end of the breathable brick by the role of high temperature molten steel, the temperature rises steeply, blowing argon, cooled by the cold airflow, the material produced a large internal thermal stress. At the same time, the ladle ladle injection of molten steel, but also produces a large temperature change, so the use of breathable bricks is very harsh conditions, very easy to produce thermal spalling and structural spalling.
(5) Requirements for easy installation, safe and reliable. Breathable brick is installed in the bottom of the ladle seat brick inside, the working conditions are extremely harsh, the life of the ladle breathable brick can not be synchronised with the life of the entire ladle, so the need to replace the breathable brick. Therefore, the installation operation is simple, safe and reliable, to avoid the occurrence of steel seepage and leakage.
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