Factors causing damage of refractory bricks
1、 Chemical factors
1.
1)Chemical erosion of molten slag (including chemical erosion of melting furnace dust).
It is generally the main factor for the corrosion of refractory brick lining in smelting furnace.
2)Chemical attack of furnace gas.
It mainly refers to that refractory bricks are gradually oxidized and eroded in oxidizing furnace gas at high temperature.
3)Chemical erosion between refractory bricks
If acid and alkaline refractory bricks are mixed, fusible compounds will be formed at the contact at high temperature, causing both to be eroded at the same time.
4)Electrochemical erosion.
Anode (zinc) of copper zinc battery. The principle of electrochemical erosion of carbon refractory bricks is the same. In high-temperature smelting furnace (such as oxygen steelmaking converter), when carbon containing refractory bricks (such as tar bonded bricks) are mixed with other refractory bricks, batteries may be formed. Molten slag is equivalent to electrolyte, and carbon containing refractory brick becomes anode, which is damaged due to carbon oxidation.
2、 Physical factors
1)Refractory brick cracking caused by drastic temperature change.
2)High temperature melting caused by high temperature.
3)The re burning shrinkage or expansion of refractory bricks will not only damage the furnace body, but also shorten the service life of refractory bricks.
4)Improper oven drying, rapid temperature rise, excessive thermal expansion of refractory bricks, damage the furnace body and shorten the service life of refractory bricks.
5)The liquid metal penetrates into the refractory brick through the obvious pores of the refractory brick, or into the brick joint. After condensing into a solid state, the volume expands to produce stress and accelerate the fracture of the brick.
3、 Mechanical factors
1.
1)The mechanical impact on the furnace bottom and furnace wall is an important reason for the rupture of refractory bricks.
2)The flow of liquid metal (such as electromagnetic stirring of metal melt in induction melting furnace) causes mechanical wear on the inner surface of furnace lining.
3)The arch roof of high temperature furnace is damaged by softening and deformation of the inner side of refractory brick due to excessive extrusion pressure.
The above three causes of refractory brick damage often exist at the same time and aggravate each other in some industrial furnaces. For example, the surface after chemical erosion is easy to be worn by mechanical impact, and mechanical erosion continuously exposes new surfaces of refractory masonry to accelerate chemical erosion.
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