The carbon blocks and the cold ramming paste can both be used for the construction of the ferroalloy furnace lining. When the linings, especially cold ramming paste linings, can not meet the specified requirements, and the oven lining time and temperature rise rate are not strictly controlled during baking, the baking of the furnace linings will not meet the normal requirements.According to the analysis of the causes of ferroalloy electric furnace lining damage, the main measures to extend the service life are as follows
For refractory carbon blocks, it is usually required that the ash content is not higher than 6%, the volatile content is not higher than 0.6%, and the high-pressure strength is not less than 260kg/cm3. It is required that a 1.2m-long vertical carbon block will not break when it falls to the ground.
Cold ramming paste should meet the requirements that the ash content should not be higher than 8%, the volatile content should be controlled between 9.5% and 10.5%, and the bulk density after ramming should not be less than 1.9g/cm3.
When carbon bricks are used as furnace lining, a large amount of tar and asphalt will volatilize during the furnace construction,before building a furnace, the number of fans in the furnace mouth should be increased to improve the operating environmen. After each layer of carbon blocks is laid, it is best to pre-bake it and maintain the temperature at 90~110℃ for 4~8 hours.
When the furnace lining is cold ramming paste, it is better to lay a layer of 400~600mm thick carbon block under the cold ramming to prevent the upper layer from being cold rammed locally. After the area is destroyed, the molten iron further penetrates downward, which can significantly extend the service life of the furnace lining.
In addition, regardless of whether carbon blocks are used for masonry or cold ramming, in addition to leaving a sufficiently wide expansion joint in the furnace wall, a 30-50mm thick expansion joint must also be considered at the furnace bottom to prevent expansion damage when the overall temperature of the furnace lining rises.
For the furnace lining made of carbon blocks, there are not many requirements for the furnace oven. However, if cold ramming paste is used as the furnace lining, the requirements for opening the furnace are higher. A more detailed plan and temperature rise curve should be drawn up before the furnace is baked.
On the one hand, it is necessary to control the depth of electrode insertion and keep a sufficient distance from the furnace bottom to avoid damage to the furnace bottom lining due to the high temperature of the electrode arc. In addition, within 1 hour before tapping, try to avoid the squeezing operation of the electrode on the furnace bottom.
Paying attention to the above aspects can effectively extend the life of the ferroalloy furnace lining.
Specializing in refractory materials for over 20 years, we provide professional refractory solutions for the global high temperature industry.