Rotary kilns have been lined with 70% Al2O3 brick for many years, and a typical
choice has been calcined bauxite/clay base types. These bricks provide sufficient
permanent expansion to keep the lining tight against the shell of the rotary kiln.
This, in turn, prevents movement of brick as the kiln rotates.
The 70% Al2O3 class bricks typically develop a “cobblestone street”
appearance in service. This appearance is not necessarily an indication of an
impending failure of the lining. In one instance, an inexperienced operator
decided to replace the 70% Al2O3 bricks with andalusite/clay bricks that had
“superior” spalling resistance in laboratory tests. The result was an unusually premature
failure of the new lining. Because the andalusite/clay bricks had only a
small permanent expansion, the bricks became loose during kiln rotation, resulting
in progressive loss of the lining by bricks “falling out” of the lining. While the
replacement of the old 70% Al2O3 lining was done for a few good reasons, the
person making the decision did not consider all the criteria that contributed to
many years of success with the 70% Al2O3 lining practice.
Rotary kilns have been lined with 70% Al2O3 brick for many years, and a typical
choice has been calcined bauxite/clay base types. These bricks provide sufficient
permanent expansion to keep the lining tight against the shell of the rotary kiln.
This, in turn, prevents movement of brick as the kiln rotates.
The 70% Al2O3 class bricks typically develop a “cobblestone street”
appearance in service. This appearance is not necessarily an indication of an
impending failure of the lining. In one instance, an inexperienced operator
decided to replace the 70% Al2O3 bricks with andalusite/clay bricks that had
“superior” spalling resistance in laboratory tests. The result was an unusually premature
failure of the new lining. Because the andalusite/clay bricks had only a
small permanent expansion, the bricks became loose during kiln rotation, resulting
in progressive loss of the lining by bricks “falling out” of the lining. While the
replacement of the old 70% Al2O3 lining was done for a few good reasons, the
person making the decision did not consider all the criteria that contributed to
many years of success with the 70% Al2O3 lining practice.
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