Gypsum calcining apparatuses and methods

An apparatus for calcining gypsum, the apparatus comprising:

• a housing having opposite first and second lateral walls, an inlet, and an outlet;
• at least one burner assembly connected to the housing, the burner assembly comprising:
• a burner,
• a fluidization plenum, and
• a serpentine burner conduit at least partly extending through the housing and to the fluidization plenum,
• wherein the fluidization plenum comprises a first end and a second end, a first space defined between the first end and the first lateral wall and a second space defined between the second end and the second lateral wall to enable thermal expansion of the fluidization plenum,
• a first fluidization box coupled to the housing at the first space;
• and
• a second fluidization box coupled to the housing at the second space,
• wherein the first fluidization box is configured to flow air into the housing through the first space and wherein the second fluidization box is configured to flow air into the housing through the second space.