My questions from all of you is that rotary kiln acts as a reactor as there is reactions involve to remove the the water of crystalization like in the following reaction in care of rotary kiln for the production of alumina. 

Al(OH)3.3H2O = Al2O3 +3H2O 

my question is why we dont consider it while designing the rotary kiln. reaction kinetics and all other stuff which we use to design a real reactor. regards