How to dry kaolin

　　The drying performance of kaolin refers to the performance of kaolin slurry in the drying process. Including drying shrinkage, drying strength and drying sensitivity.

　　Drying shrinkage of kaolin refers to the shrinkage of kaolin slurry after dehydration. Generally, the kaolin slurry is dehydrated and dried at 40-60 ℃ and no more than 110 ℃。 Due to the water discharge, the particle distance is shortened, and the length and volume of the sample will shrink. The drying shrinkage is expressed as the percentage of the change of the length and volume of kaolin slurry after drying to constant weight. The drying line shrinkage of kaolin is generally 3-10%. The finer the particle size, the larger the specific surface area, the better the plasticity and the larger the drying shrinkage. The shrinkage of the same type of kaolin is different because of the different mixing water. In ceramic technology, the drying shrinkage is too large, and the body is easy to deform or crack.

　　The dry strength of kaolin refers to the flexural strength of the clay after drying to constant weight.

　　The drying sensitivity of kaolin refers to the degree of difficulty of deformation and cracking tendency when the green body is dry. High sensitivity, easy to deform and crack in drying process. Generally, the kaolin with high drying sensitivity （drying sensitivity coefficient k > 2） is easy to form defects, while the kaolin with low drying sensitivity （drying sensitivity coefficient K < 1） is relatively safe in drying.

　　Drying equipment overview:

　　1、 Working process of drying equipment:

　　After the normal temperature air is heated by the heater, it enters the drying tower through the hot air pipe on the top of the tower. Under the action of the orifice plate air equalizer, it is evenly covered with the circular surface, and under the action of the induced draft fan, it flows downward. The liquid raw materials are sucked out of the raw material tank by the high-pressure homogenization pump, and ejected through the spray gun. Under the high pressure and through the structural design of the spray gun, the liquid raw materials are atomized into small droplets, and the surface area is greatly increased, When the atomized raw material contacts with high temperature air, the moisture will evaporate immediately and become solid particles or powder （the particle size of the product can be changed by adjusting the atomization pressure）， which will move downward together with the tail gas. Most of the powder particles will be discharged from the bottom of the tower. The tail gas and a small amount of small powder will be sucked out by the air outlet pipe. Through the cyclone separator, the powder will be discharged by the cyclone discharger, The tail gas is drawn out to the spray scrubber by the induced draft fan, and the purified gas is discharged

　　2、 The relationship between the properties of kaolin products and the adjustment parameters:

　　1. The particle size of kaolin is changed by the adjustment of atomization pressure and spray gun aperture

　　2. The moisture content of kaolin product is changed by the adjustment of exhaust temperature and residence time of material in the tower

　　3. The collection method of kaolin products is determined by parameters such as product value, fineness, specific gravity and so on. Ordinary pressure spray is a cyclone separator.

　　Three. Comparison between pressure spray drying equipment and centrifugal spray drying equipment:

　　1. The viscosity of raw materials for pressure spray drying equipment is larger than that of centrifugal spray drying equipment, which mainly depends on the working conditions and atomization effect of high pressure pump.

　　2, the pressure spray drying equipment spray tower is thin and high structure, and centrifugal spray is coarse and short structure, which is mainly determined by atomization principle of both. The pressure atomization is pressure atomization, and most of them are downstream （upward and downward）， so the material moves downward faster. In order to ensure that the material can dry in the air, it is highly high, but the diameter is not too large. Centrifugal spray is just the opposite.

　　3. The size range of pressure sprayed products is larger, or even smaller.

　　4、 Main maintenance parts of drying equipment:

　　1. Feed pump: it works in high-pressure environment for a long time and needs regular maintenance, but only needs routine maintenance, which is also convenient.

　　2. Spray gun: due to the continuous and high-speed spraying of materials from the spray gun mouth, the spray gun will be greatly worn, and after wear, the atomization effect will be seriously affected, thus affecting the product quality. Regular inspection and replacement of vulnerable parts should be carried out.

　　3. Fan, heater, etc.: normal maintenance.