Factors affecting the ventilation function of ventilation bricks

Breathable brick is a kind of functional refractory material with high life span, energy saving, consumption reduction and emission reduction. The essence of ferrous metals outside the furnace and the smelting of non-ferrous metals. Let's take a look at the factors that affect the ventilation function of breathable bricks.

1. The effect of airway scale on ventilation function

In the use of slit-type breathable bricks, the slits are easily intruded by molten steel to form steel clips, and the air permeability becomes smaller. It is difficult to blow argon, and the liquid steel has small blooms, so it is difficult to achieve the effect of pure molten steel. About the breathable bricks that must be used in large ladle In other words, in order to ensure the air permeability, the size and number of slits must be stable and not too small. Steel clipping is unavoidable for slit ventilation bricks, and the penetration of molten steel cannot be quantified, but it can be determined from the size and size of the slit airway. Materials to reduce clip steel as much as possible, suitable slit airway size and materials with better thermal stability are beneficial to reduce clip steel.

After dissection of the remaining bricks, it was found that the thickness of the clip steel sheet is much larger than the thickness of the air passage, and the closer it is to the working face, the thicker it is, while the thickness of the steel sheet far from the working face is thin and conical distribution. The reason is that under the effect of high temperature molten steel , The area near the interval of the breathable bricks for argon blowing is subjected to thermal stress, and some of the stress that occurs is concentrated near the airway, causing the airway to change in size during use, resulting in the easy intrusion of molten steel and affecting the breathable function. If the valve is closed quickly after completion, the molten steel will enter the slit with positive pressure, which will also lead to steel infiltration and affect the ventilation function.

2, the effect of cracks on the ventilation function

The ladle to be used must be baked before use to reduce the temperature difference. But even so, the surface temperature of the breathable brick installed at the bottom of the ladle still does not reach 1000 degrees Celsius, and the breathable brick is directly impacted by molten steel above 1600 degrees Celsius when tapping ; When blowing argon, the large flow and high-speed normal temperature argon make the temperature of the slit part of the permeable brick drop rapidly, so that a large temperature difference occurs inside the permeable brick. These two points are the main factors that cause cracks in the permeable brick. The temperature gradient is mainly concentrated It is 30mm below the working surface of the permeable brick, so the cracks caused by thermal stress will also be concentrated in this area. During the argon blowing cycle of the permeable brick, it is easier for the molten steel to invade the brick body along the cracked air passage due to the occurrence of cracks. , forming molten steel infiltration, which will seriously affect the argon blowing fruit.