The subject invention relates generally to methods and apparatuses for calcining gypsum. The apparatuses and methods place a gypsum particle optimizer in close association with the impact mill so that all the gypsum supplied to the impact mill has to enter the gypsum particle optimizer prior to the gypsum entering the impact mill, and so that heat generated from the impact mill enters into the gypsum particle optimizer from the impact mill. The gypsum particle optimizer utilizes a rotor to disperse the gypsum throughout the gypsum particle optimizer so that the gypsum is exposed to the heat from the impact mill prior to entering the impact mill. The exposure to the heat removes free water from the gypsum prior to the gypsum entering the impact mill.