Study On Technology Of Alpha-alumina From Rotary Kiln

Calcinedα-Al2O3 alumina, also called high temperature alumina, is the most stable state of eight kind of same type isomers. It is widely used in electronic ceramics, structural ceramics, advanced refractories, abrasives, grinding media, mechanical equipment and raw materials lining for its excellent mechanical properties, high temperature performance and insulation properties. With the development of industrial technology, calcinedα-Al2O3 is increasingly used in more areas than before, their consumption is also growing. In this paper, series laboratory and industrial experiments were conducted to solve high crystal particle size, lowα-phase,high sodium oxideand and other problems in calcinedα-Al2O3 production line in Shandong branch of Chalco. Various raw materials were studied to determine the appropriate use ofα-Al2O3 ceramic ball production process. Based on these experiments, calcination temperature, calcination time, raw material selection and mineralizer were optimized. The effects of product performance and ultimately, a better rotary kiln to determineα-Al2O3 optimized processing conditions are as follows:(1) raw material selection:the sintering process seed aluminum hydroxide as the calcinedα-Al2O3 raw material, micro-particles into a more regular spherical, grain size is small; D50 optimal particle size range of aluminum hydroxide in 80～95μm.(2) calcination temperature:1300℃～1400℃, need to adjust fuel capacity by feeding amount, a cyclone exit temperature control range of 380～400℃.(3) mineralizer:Kiln added 0.2%to 0.5%boride could obtain 1.5μm≤D50≤2μm calcined a-Al2O3, and boron is useful to improve the conversion rate of a phase, therefore, boric acid was suggested as mineralizer in industrial production.(4) calcination time:extension of calcination time could promote the original grain size of α-Al2O3 grow and improve conversion rates, while ensuring product quality conditions, actually control of 30 to 60 minutes.The results of the domestic production of calcinedα-Al2O3 has important theoretical and practical significance.