The preparation of alumina hollow ball brick needs to manufacture alumina hollow ball first. The preparation methods of alumina hollow ball include rolling ball loss of ignition method and melting injection method. In the rolling ball method, the core pellet is made of organic resin or low melting material, placed in a rotating disc, and then the moist fine alumina powder containing a certain amount of water is sprinkled on the disc, adhered to the core pellet to form a shell, just like wrapping a layer of sugar coating on the pill. Then the pellets are fired at high temperature, the core pellets are lost and volatilized, and the shell is sintered to form a hollow ball. The disadvantage of this method is that the efficiency is low, the spherical surface is not smooth, and the wall thickness and size are not easy to control, so it is not widely used in industrial production.
Detailed production steps of alumina hollow ball brick
Industrial Al2O3 is used as raw material to melt directly in electric arc furnace. Electric arc furnace can be single-phase or three-phase type, and three-phase is better. The furnace body is equipped with a tilting device, and the discharge port is equipped with a gas nozzle at a certain angle. The furnace lining material is graphite. Assuming that the furnace diameter is 550mm, the furnace height is 300mm, the graphite electrode diameter is 150mm and the electrode circle radius is 150mm, the smelting voltage is 100V and the current is 1500~1700a. During the melting process, alumina fine powder is added gradually and intermittently until the melt reaches a sufficient amount. When all the materials are melted, the viscosity of the melt is appropriate, and the temperature of the melt is about 2200~2300 ℃, the furnace body can be tilted to make the melt flow out of the discharge tank. At the same time, open the air valve, and blow the liquid flow into droplets with compressed air with an exhaust volume of 10m3/min and a pressure of 0.6~0.8mpa. The droplets solidify rapidly in the air during flight due to the effect of the viscosity and surface tension of the melt, forming shell shaped spheres, which are collected in the collection chamber. After sorting, screening or rinsing, the frit fragments, large balls and small balls with particle size greater than 5mm or less than 0.2mm are removed, and the qualified hollow balls with particle size of 5mm to 0.2mm are classified according to particle size.
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