Key Factors Affecting the Performance of Jet Mill Pulverizers

As the name suggests, a jet mill pulverizer uses high-speed airflow to achieve ultra-fine grinding.  While its basic function is easy to understand, many users are not familiar with the deeper principles and the factors that influence its performance.  Below are the major factors that determine the efficiency and final particle size of a jet mill.

1.  Material Characteristics

Jet mills are suitable for most brittle materials, but the grinding performance varies significantly depending on material properties such as:

• Strength

• Density

• Hardness

• Viscosity

• Particle shape

• Electrical properties

Among these, material strength is one of the most critical factors affecting grindability.

Additionally, excessive moisture or oil content in either the material or the compressed air can increase the toughness and viscosity of the particles, resulting in poorer grinding fineness.

2.  Processing Capacity (Feed Rate)

Even for the same material, different feed rates can produce different particle sizes.  In general, the processing capacity is positively correlated with the final fineness.

However:

• If the feed rate is too low, particle-to-particle collision decreases, reducing grinding efficiency.

• If the feed rate is too high, the grinding chamber may become overloaded, affecting stability and fineness.

Therefore, selecting an appropriate feed rate based on the equipment specification is essential.

3.  Influence of Back Pressure

Back pressure refers to the average gas pressure inside the grinding chamber.  The jet velocity of the nozzles is determined by the pressure difference between the inlet and the outlet.  A larger pressure difference results in higher jet velocity and better grinding efficiency.

If back pressure rises, the pressure difference decreases, leading to:

• Reduced airflow speed

• Weaker impact force

• Lower grinding efficiency

In production, increasing resistance in the dust-collection or cyclone system can raise the back pressure of the jet mill.  Therefore, it is important to regularly inspect and maintain the collection system to ensure stable performance.