Air classifiers are machines used in industrial processes to sort different bulk materials. They also help control air pollution and process building materials, chemicals, minerals, powder coatings, and food ingredients. By using moving air, these machines efficiently and quickly separate materials based on particle density, shape, and size, often preparing them for further processing.

Using Air Classifier Machines to Enhance Products 

Today's air classifier machines use physics, innovative designs, and advanced technology to classify dry bulk solids. These machines separate particles based on size, shape, and density differences as they respond to moving air currents. Modern air classifiers have control systems that let operators regulate airflow precisely, adjusting particle movement within a processing system. This capability makes them valuable for many bulk material processing applications.

Advantages of air classifier machines in bulk material handling include:  

  • Energy efficiency: Many manufacturers utilize air classifier machines within their processing systems due to their lower energy usage, making them more economical.
  • Environmentally friendly: As it’s a dry process, air classification reduces the need for water in material processing applications, especially when compared with conventional wet classifying techniques. 
  • Precision: These machines precisely separate particles to produce materials of sufficient quality for multiple applications and industries.
  • Versatility: An air classifier's operational parameters are easy to adjust, and machines are capable of producing multiple particle sizes and distributions for a wide range of materials.

Several factors determine the effectiveness of an air classifier machine. The particles' density, shape, size, and moisture content all play a role. Understanding the material's properties is essential to predict particle behavior in classification. For instance, grain moisture content can affect classifier performance, possibly requiring adjustments in feed rates or airflow. In the case of minerals, size and density often guide the choice and timing of the air classifier machine.

Working Principles of Air Classifier Machines

Though their operation is complex, air classifiers possess an elegant simplicity. These machines use moving airstreams to fluidize and convey particles for separation using various forces that play on the particle's different densities and sizes. 

Air classifiers achieve precise and efficient particle classification for various materials and applications by adjusting airflow, feed rates, and other parameters. They use centrifugal force to separate particles along a defined pathway. As raw material enters, moving air causes aerodynamic drag, influencing particles based on their size and density.

The classification revolves around the rotor, where smaller, lighter particles overcome the centrifugal force and pass through as fine material. In contrast, heavier particles are pushed away from the rotor and collected below as coarser material.

The balance between the rotor's centrifugal force and the drag from moving air is crucial for air classifiers. When these forces are equal, about half of the material's particles pass as fines, which can be adjusted by changing the rotor speed. Some machines feature a secondary air inlet for additional airflow, prolonging the time larger particles spend in the classification zone allowing them to be sorted with finer material.

Industrial Applications of Air Classifier Machines

Air classifier machines are typically used for fibrous, fine, and lightweight materials and various types of waste. These machines are effective when there are significant differences in particle densities, shapes, and sizes, which is why they are commonly used in specific industries.

Materials, industries, and applications for which air classifier machines are used include:  

  • Chemical processing: Air classification aids in the separation of chemical particles based on their physical characteristics, which is important to ensure quality.
  • Dust: The centrifugal force applied by the air classifier’s rotor is ideal for removing fine dust particles from bulk materials.
  • Food processing: Air classifier machines help ensure uniformity of spices and grains, a key factor in upholding the quality of food products.
  • Mineral processing: Air classification systems provide a more environmentally friendly means of separating valuable minerals from ores, which would require considerable water.

The efficiency of air separation allows for precise and rapid sorting. This highly accurate process improves the quality of bulk materials, while the use of air lowers equipment wear and energy consumption.

Prater Air Classifier Machines

Prater Industries designs air classifier machines for dry bulk materials needing very fine particle separation, with sizes ranging from 3 to 150 microns. Made from carbon or stainless steel, our machines are built for durability and precision. The classifiers allow for efficient separation and are easily controlled by adjusting rotor speed. Additionally, an adjustable air system helps capture more near-size particles and is designed for energy efficiency.

Prater offers the following air classifier machines: 

  • MAC air classifier: Used as separate systems with integrated feeder, fan, and collection equipment or for conventional milling systems within a closed circuit, MAC air classifier machines bring superior uniformity and fineness to processed dry materials.
  • Mini-split air classifier: Initially developed for research and smaller material handling operations, mini-split air classifier machines are well-suited to more confined workplaces. Their reduced noise and portability give them ample flexibility.

Engineered to last, Prater’s air classifier machines perform exceptionally over their life. This patented classifier design causes feed material to enter the classification vortex without recirculated particles hindering the process. Our air classifiers also feature an adjustable ancillary airstream to improve the collection of materials. Installation into existing pneumatic systems can be done quickly with only marginal alterations. To learn more about our air classifier machines and other material processing equipment, we invite you to check out Prater’s catalog. For more information about our products and services, contact a representative at Prater today.