Modified calcination of coal series kaolin is to obtain special physical and chemical properties through high temperature dehydroxylation and decarburization. Calcination of kaolin at appropriate temperature will change the crystal structure of kaolin, from the original ordered lamellar crystal structure of kaolin to the disordered structure of metakaolin; With the increase of particle size, the surface energy decreases and its dispersivity increases; The increase of hardness leads to the improvement of wear resistance; Enhanced acidity; Improved electrical performance; Whiteness increases.

During the heating process of kaolin, heat absorption or exothermic effect is caused by water loss and crystal phase change. Different temperature will cause different phase changes of kaolin, and the specific reaction process is as follows:

Compared with the traditional calcination equipment, the flash cyclone dynamic calcination system independently developed and designed by Yuneng Mechanical Engineering Technology Co., Ltd. (Yuneng Technology) shows in the kaolin calcination test results that the calcination of kaolin based on the fluidization of powder has good dispersion of materials in the high fraction state, does not agglomerate, the materials are directly contacted with high-temperature hot air, has large heat exchange area, convenient temperature control, high thermal efficiency, and calcination time, Small equipment investment. The application of flash cyclone dynamic calcination technology in production can change the traditional production process, shorten the material reaction time, greatly increase the output, and achieve large-scale and continuous production of kaolin with low energy consumption and small floor area.

Yuneng Technology Kaolin Flash Cyclone Dynamic Calcination Technology has the following characteristics:

● The furnace temperature control is convenient, and the fuel and furnace temperature can be automatically controlled to meet the quality index requirements of high product quality and military assistance;

● The kiln is suitable for continuous and large-scale production, with short calcination time to improve productivity, reduce energy consumption and production cost;

● The kiln occupies less land and has small investment, low labor intensity and strong controllability;

● The calcination process has no external pollution and can meet the requirements for high whiteness of the product.

Introduction to the process of flash cyclone dynamic calcination system

Process description

Drying unit: the raw materials are continuously transported into the flash dryer (the inlet air temperature of the dryer is 450~550 ℃) through the metering belt conveyor and the spiral feeder. The heat source of flash dryer comes from the flue gas after calcination in the calciner. In the flash dryer, the wet materials are rapidly dispersed into powder under the combined operation of the rotating blades of the main machine and the fast thermal flow of the main machine, and the content of the wet materials in the materials is ≤ 0.5~1% in 3-5 seconds. The dried materials and smoke mixture are carried to the cyclone separator and the pulse bag type dust collector in turn by the cyclone flow for solid separation. The dried materials and smoke mixture are preheated before calcination. After being purified by the bag type dust remover, the tail pipe is led out by the induced draft fan (the outlet temperature is about 160 ℃).

Preheating unit: the material enters the preheating section and moves counter current with the heat carrier. The heat carrier moves upward in the preheating unit and is discharged from the top of the cyclone separator; The material flows downward and is discharged through the lower discharger of the third stage preheater to complete the preheating process and enters the calcination unit.

Calcination unit: in the Yuneng dynamic furnace, the flame burns continuously in the combustion chamber to produce warm smoke. The air temperature is adjusted by mixing secondary air (or no cold air), and the preheated materials are mixed with warm smoke to complete the calcination sequence. As the powdery materials are accumulated on the surface and floated in the hot body for single particle calcination, the raw materials are rapidly decomposed. The material is carried in the calciner by the carrier hot air and the calcination process is completed in seconds. The path of the material is 80~130m. After the materials leave the calciner and enter the temperature cyclone, the solid will be separated. The finished materials leave the calcination unit and enter the cooling unit, and the warm smoke returns to the preheating unit to preheat the raw materials.

Cooling unit: the calcined materials are cooled by multi-stage cooling cyclone.

The flash dynamic cyclone calcination system of Yuneng Technology is completely suitable for the calcination requirements of coal series kaolin, which is a reasonable and economic calcination process.

Yuneng Science and Technology flash cyclone dynamic calcination system compared with traditional rotary kiln calcination system

Process calculation

Production capacity: 3000 tons of finished products/year

Heat consumption: 1500 kcal/kg finished product

Fuel calorific value: 10000 kcal/kg

Carbon content of coal series kaolin: 1~2%

Chemical water content: 11.78%

Specific heat of coal series kaolin:

Before calcination: 0.991 kJ/kg · ℃

After calcination: 1.092 kJ/kg · degree

Density of coal series kaolin: 2.54t/m3

Excess air coefficient: 1.40

Chemical composition of fuel: C: 85.60%; H：13.20%； S：1.20%

Particle size of raw material: 325 mesh

Chemical composition of raw materials: (see the table below)