Brief analysis of methods to increase the rate of ladle blowing (1)

(Picture) GW series slit-type air-permeable brick

We have made an analysis on the performance and life of the air-permeable bricks. For details, please refer to other contents of this website. In this article, we specifically discuss methods to increase the rate of ladle blowing.

1. Strictly select the material of bottom blown and breathable bricks

Corundum is selected as the main crystal phase of the air-permeable brick, and then a small amount of additives that form a solid solution with the main crystal phase are added as a sintering agent, and at the same time an appropriate amount of Cr2O3 is introduced. The reasons are as follows:

In a high-temperature vacuum environment, the order of stability of several types of refractory oxides is: Al2O3>CaO>MgO>Cr2O3, and the order of the wetting angle of molten steel is: ZrO2>Al2O3>MgO. On the whole, corundum is undoubtedly the best choice as the main crystal phase of breathable bricks.

The melting point of Cr2O3 is 2 275 ℃, which is higher than the melting point of Al2O3 by 2 050 ℃. The formed Al2O3-Cr2O3 solid solution can significantly enhance the corrosion resistance to iron oxide or slag, and it can also inhibit the excessive growth of Al2O3 crystals and reduce The internal stress of the crystal improves the thermal shock resistance of the material. However, the amount of Cr2O3 should not be too much, otherwise, the growth rate of corundum grains will be seriously affected, thereby reducing the performance of the material.

2. Choose a good-structure breathable brick

There are many types of airway structures for bottom-blown ventilating bricks:

(1) Early dispersive structure, small and penetrating pores, high porosity, but low-grade materials and poor durability;

(2) The straight-through hole type is to preset multiple vertical holes in the refractory material. The bottom blowing effect is better and the service life is long. However, it is easy to be blocked in the later stage, which affects the blowing rate;

(3) The slit-type air-permeable brick is preset in the air-permeable brick or combined in a certain way to form a dozen or more air-permeable slits, through which the gas enters the ladle melting pool. Relevant data show that the slit width of the slit type is selected between 0.15 and 0.20 nm, which can ensure the strength of the bottom blowing gas, control and adjust the flow rate, and avoid the danger of permeation and blockage, and the service life is relatively prolonged. Therefore, it is a better choice to change the airway structure of the bottom-blown air-permeable brick to a radial slit type.

(4) Due to the continuous increase of the types of smelted steels and the expansion of the tapping temperature range, in order to ensure the mixing strength of molten steel, improve the adaptability of bottom-blown ventilating bricks, and solve the problem of slit deformation in the middle and late stages of ventilating bricks, some manufacturers have adopted an increase Measures such as the number of slits in the air-permeable brick and the width of adjacent slits are different to achieve the metallurgical purpose.

(5) The late diffusion structure is represented by Luoyang Kechuang’s impermeable air-permeable brick (patented product of our company). Its unique formula, design and production process make it have the advantages of the early diffusion-type air-permeable brick: small pores Through penetration, high porosity, uniform bubbles, good bubble shape, no steel penetration, no clogging, and at the same time has the advantages of slit-type air-permeable bricks: long life and high blowing rate.

3. Improved masonry technology

Change the installation of a single bottom-blowing ventilating brick at the bottom of the ladle to installing two bottom-blowing ventilating bricks at the same time, and formulate the corresponding operation process.

With the continuous introduction of new refining processes outside the furnace, especially the adoption of new processes for LF furnace ladle refining and VD vacuum treatment, the requirements for bottom-blown ventilating bricks are becoming higher and higher. Because the bottom blowing time is significantly prolonged, the service life of the bottom blowing air-permeable brick is relatively reduced in this way. In order to synchronize the service life of bottom-blown air-permeable bricks with the bottom of the ladle and further improve the bottom-blowing rate of the ladle, this method can improve the bottom-blowing rate and achieve good results.

in conclusion

In order to increase the rate of ladle blowing, it can be achieved by the following methods: 1. Strictly select the materials of breathable bricks and use the breathable brick products of well-known domestic manufacturers 2. Use impermeable breathable bricks 3. Improve the masonry technology.

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