Analysis of the reasons for the melting of secondary high-alumina bricks in the sleeve lime kiln

The firing temperature of secondary high-alumina bricks is 1410℃, the softening point under pressure is around 1430℃, and the operating temperature range is 1350℃. However, the temperature of the high-temperature zone in the lime kiln is 1200℃. If secondary high-alumina bricks melt, there are multiple reasons for this.

When the sleeve lime kiln start melting, we should firstly consider whether the air supply is too strong, or whether the input is too much and the ash discharge is not smooth, then cause blockage. The flames directly wash the kiln wall, causing the temperature to rise rapidly, resulting in local excessive temperature in the transition zone, causing the secondary high-alumina bricks to melt and erode.

The lime kiln contains limestone raw materials, and a large amount of calcium forms alkaline erosion, severely softening the surface of the secondary high-alumina bricks, causing the melt, penetrate, and erode.

In addition, frequent start-stop of the kiln and large temperature fluctuations can also cause cracks in the brick body of the secondary high-alumina bricks, leading the softening and erosion; there are also excessive mortar joints during construction, and rapid temperature rise during the baking process can cause the high-alumina bricks to crack and erode; if the sleeve kiln leaks air, the high-temperature airflow is reflected onto the transition zone kiln wall, causing local over-temperature and eroding the high-alumina bricks.

The best solution is to strictly control the mortar joints during the construction process, strictly control the kiln temperature during the production process to prevent excessive temperature fluctuations, optimize air supply and ash discharge, and prevent the temperature from rising and the airflow from being reflected. In summary, it is necessary to strictly control according to the actual production situation. If the output is significantly increased while the raw material quality declines, consideration should be given to changing to use first-grade high-alumina bricks; because first-grade high-alumina bricks do not have a certain proportion of waste bricks added, their thermal shock performance and wear resistance will be longer than those of secondary high-alumina bricks.