Abstract：Aluminum hydroxides as raw material were calcined at1 200, 1 250, 1 300 and 1 450℃ after pickling washing.Sub-micron alumina were prepared after grinding.The results show that the pretreatment of raw material can reduce mass fractions of Na₂O in raw material and products obviously, and improve the conversion rate of α-phase. The calcination temperature affects the specific surface area of products. The optimum calcination temperature is 1 300℃, at which the α-Al₂O₃ of high conversion rate of 95% and good activity can be obtained.Particles in sub-micron size of 0.73 μm are prepared after grinding for 6 h.

Keywords：aluminum hydroxide; sub-micron alumina; ultrafine powder; calcination