Introduction
Alumina ceramic is a wear-resistant, corrosion-resistant, high-strength ceramic materials. Its application is extremely extensive, and it currently Is one category in most using high-temperature structural ceramics; For forming mass production, to adapt neat product appearance, small grinding amount and requirements of easy fine grinding, selection of dry pressing molding method is very necessary. Pressing molding requires that the blank is powder with certain ratio, water and binder both are less. Therefore, it must be done to prepare the powders with good fluidity and high accumulation density, with mixing slurry after ball milling fine through drying granulating process, and thus, using spray drying granulating process, has become a basic method for producing building ceramic and new ceramic.
Powder prepared by this process has a good flowability, a certain percentage of particle size distribution, and bulk density is better. Therefore, spray drying to prepare dry pressing powder is an effective method.
Spray drying is such a process that the liquid materials (including slurry) after atomization in a hot drying medium transfer into dry powder, in which the material is atomized into very fine spherical droplets. Since the droplet is fine and the surface area to volume ratio large, so that water rapidly evaporates, drying and granulating process is completed in a moment. The grain size, moisture, bulk density of material by adjusting the parameters of drying operation control. Using spray drying technique can prepare spherical powders with uniform quality, good repeatability, shorten the preparation process of powder, and be conducive to automated, continuous production, so it is an effective method for Large-scale making excellent dry powders of alumina ceramic.
Work principle:
1. Feeding system: Slurry is transported by a hose diaphragm pump with high pressure, to the pressure type spray gun or a centrifugal atomizer for atomization after beating with a beater and filtering with a slurry filter.
2. Hot air system: air is filtered by the air filter into the direct-fired stove jacket, and then enters to the hot air distributor through a hot air pipe after mixing with high-temperature air of burning by a natural gas burner at the outlet of hearth.
3. Drying and receiving system: the hot air enters into the drying tower after allocated evenly through a hot air distributor , and after the atomized slurry sufficiently heat- exchange with it , the exhaust gas is discharged to bag type dust collector by the insertion tube; then emptying by an induced draft fan after removing dust. Particle products dried are discharged from the bottom of tower, a small amount of powders go into the bag type dust collector along with exhaust gas, after separation being discharged to the receiving barrel.
