One article to understand the fluidized bed airflow mill and its application progress!

Airflow grinder is one of the main ultrafine grinding equipment, of which fluidized bed airflow grinder has the advantages of low energy consumption, small wear, high classification accuracy, Z is widely used in the current ultrafine grinding equipment.

1. Working principle and characteristics of fluidized bed airflow crusher

Fluidized bed airflow crusher is a combination of reverse jet or opposite jet principle and expansive gas jet flow in fluidized bed. Its working principle is:

(1) The material is fed into the bin through the star valve, and the screw feeder will feed the material into the crushing chamber or directly into the crushing chamber;

(2) The supersonic jet generated by the rapid expansion and acceleration of compressed air through the crushing nozzle forms a centripetal jet flow field at the lower part of the crushing chamber. Under the action of pressure difference, the material at the bottom of the grinding chamber is fluidized. The accelerated material merges at the intersection of multiple nozzles, resulting in violent impact, collision and friction and crushing;

(3) The crushed materials move together with the rising air flow to a certain height at the upper part of the crushing chamber. The coarse particles fall back to the lower part of the grinding chamber along the wall under the action of gravity, and the fine powder moves together with the air flow to the upper turbine classifier.

(4) In the flow field generated by the high-speed turbine, coarse particles are thrown near the cylinder wall under the action of centrifugal force, and fall down to the lower part of the grinding chamber with the stall coarse powder for grinding.

(5) The fine powder that meets the fineness requirements is transported to the cyclone separator through the classifier runner through the exhaust pipe for product collection. A small amount of fine powder is further separated from gas and solid by the bag catcher, and the purified air is discharged from the machine by the induced draft fan.

(6) Connecting pipe can keep the pressure of silo and crushing chamber consistent.

(7) The upper and lower material level of silo is automatically controlled by the precise material level sensor to feed the star valve, and the material level of the crushing chamber is automatically controlled by the dynamic current transmitter on the classifier to feed the screw feeder, so that the crushing is always in the best state.

Fluidized bed jet mill type is unique is its traditional airflow mill line, face the impact crushing into a three-dimensional impact crushing, and the spray impact generated by high speed jet can be used in the crushing chamber, the material flow to produce similar to grinding indoor flow state of gas-solid flow crushing and classification cycle effect, improves the impact crushing efficiency and energy utilization, Other features are as follows:

High crushing efficiency, low energy consumption: the airflow particles are multi-angle collision, the force is large, the force of the powder is complex, the external energy is fully absorbed by the powder, the loss of jet work is less; By combining the principle of fluidized bed with the horizontal turbine superfine classifier, the fine material can be discharged in time and the energy loss caused by the overcomminution of fine powder can be reduced. Compared with disc air mill, the average energy consumption is reduced by 30~50%.

Light wear, less pollution: from the first impact, the powder is mainly collision with each other, less impact on the outdoor wall.

Small volume and small floor area: on the premise of the same production capacity, the volume and floor area of fluidized bed collision airflow mill can be reduced by 10~15% and 15~30% than that of disk airflow mill.

High degree of automation, low noise, large production capacity, suitable for large-scale industrial production.

2. Application and research progress of fluidized bed jet mill

Fluidized bed jet mill type at present has been widely used in synthetic resin, phenolic resin, PVC, the pigments and dyes, powder coating, coupler, western medicine, Chinese medicine, pesticide, cosmetics, pollen, magnetic powder, abrasive, metal powder, food, spices, stearic acid, fat, wax, chemical, metallurgical, kaolin, talc, mica, bentonite, quartz, calcite, wollastonite, oxygen Aluminum, zircon, graphite, lithium battery anode and cathode materials, flame retardant materials, ceramic materials and other ultrafine grinding processing.

Quartz: Guo Xiuping et al. prepared ultrafine quartz powder by fluidized bed airflow crusher. Two kinds of products, D95 =10μm and D97 =6μm, could be obtained in cyclone separator and pulse bag filter respectively.

Zirconia: Shen Hui et al. used fluidized bed airflow mill to process zirconia, which can obtain uniform and stable quality, high purity and ultrafine, and D50 <1μm zirconia powder.

Wollastonite: Yang lm using fluidized bed jet mill type such as the preparation of high aspect ratio wollastonite, wollastonite particle average length to diameter ratio on the particle size of 4 ~ 6 microns can reach 1 ~ those days, when the average etc. After more than 6 microns in diameter, volume average length to diameter ratio changed little and the average volume diameter increased a lot, such as mean volume diameter less than 4 microns mean length to diameter ratio fell sharply.

Cerium oxide: Zhou Xi et al. prepared ultrafine cerium oxide by fluidized bed air flow mill in the dry state, the product particle size range is 1-5 μm, and the yield is high Z, Z ideal process parameters matching 85mm acceleration distance, crushing pressure 0.85mpa, classifier speed 1050r/min, its yield can reach 53kg/h.

Molybdenum powder: Wuzhou et al. used micro fluidized bed airflow mill to treat ordinary molybdenum powder. After treatment, the bulk density and vibration density of molybdenum powder were greatly improved, the particle size distribution became narrow, the D50 decreased significantly, the particle morphology was uniform, and the aggregate was opened. The fine size of molybdenum powder can be effectively adjusted in a certain range by properly adjusting the speed of the classifier.

Nano zinc oxide: Cao Zhi et al. used airflow pulverization modification process and stearic acid as modifier to deaggregate and surface modify nano zinc oxide. After modification, the particle size of nano-zno is 292.6nm, and the effect of agglomeration is obvious.

Talc powder: Palaniandy et al. prepared talc powder micropowder by airflow pulverization technology, and the ultra-refined talc powder showed great mechanochemical effect, with the microcrystal size ranging from 147.69 nm to 353.72nm and the lattice strain ranging from 0.08 nm to 0.2.

Siliceous soil: Palaniandy et al. used fluidized bed airflow crusher to treat the siliceous soil. After grinding, the particle size of siliceous soil decreased and the mechanochemical effect occurred simultaneously. The microcrystalline size ranged from 22.71 nm to 35.54nm, and the lattice strain ranged from 0.024 to 0.038.

Tourmaline powder: When the diameter of the nozzle is 13mm and the speed of the classifier wheel is 3900r/min, tourmaline powder d50=3.390μm and D50 =1.961μm can be obtained from the cyclone and bag dust collection respectively.

Straw straw: Jin et al. used fluidized bed airflow mill to separate fiber components from steam-treated straw straw with high moisture content, and obtained ultrafine grinding products with average fiber length of 60μm, with a yield of 78%, 2.79 times that of untreated straw.

Pearl powder: Chen Shuqin et al. prepared pearl powder and pearl layer powder by fluidized bed airflow crusher with pressure of 0.8mpa, feeding speed of 45kg/h, and speed of classifier 8000rpm. The fineness and yield of pearl powder were the best.