A method includes transferring at least one feed stream including calcium oxide, calcium carbonate, water, and a fluidizing gas into a fluidized bed; contacting the calcium oxide with the water; based on contacting the calcium oxide with the water, initiating a hydrating reaction; producing, from the hydrating reaction, calcium hydroxide and heat; transferring a portion of the heat of the hydrating reaction to the calcium carbonate; and fluidizing the calcium oxide, calcium hydroxide, and the calcium carbonate into a first fluidization regime and a second fluidization regime. The first fluidization regime includes at least a portion of the calcium carbonate and at least a portion of the calcium oxide, and the second fluidization regime includes at least a portion of the calcium hydroxide and at least another portion of the calcium oxide. The first fluidization regime is different than the second fluidization regime.