Rotormills, often called long-gap mills because of the extended ringed gap located between the entry point and discharge point of the product, are capable of enhancing the characteristics of materials during the milling process. These machines are utilized across a wide range of industries, including agriculture, chemicals, energy, food processing, metallurgy, pharmaceuticals, and waste management.

Understanding the Long Gap Design: How Rotormills Work

Rotormills generate significant turbulence, causing particles to collide at high speeds. Inside the grinding chamber, an internal rotor helps crush the material into finer particles. These machines consist of two main sections: the lower section functions as a fan, propelling the material upwards into the upper section of the chamber, where it is further pulverized.

Fundamentally, rotormills are impact mills with a vertical shaft connecting both housing segments. The material enters the machine and is pushed upward through the chamber by airflow originating from beneath. This design ensures that coarser particles remain in the chamber longer until they achieve the desired fineness.

In the upper portion, grinding plates accelerate both air and material as they make contact with the interior surfaces. Rotating air pockets assist in breaking down the material, while continuous airflow keeps internal temperatures low. Additionally, collisions between particles aid in the grinding process.

Advantages of Using Rotormills

Rotormills provide several benefits compared to traditional milling equipment. Their innovative design allows for the fine grinding of diverse bulk solids without relying on screens, which are typically necessary to maintain sufficient retention time in other technologies. In a Rotormill, residence time can be adjusted to some extent by regulating the speed of the air flow within the machine.

These machines are highly versatile, capable of handling abrasive and difficult-to-crush materials, reducing processing times and cutting costs. They excel not only in size reduction but also in classification and conveying tasks, ensuring precise control over the fineness of processed materials. Furthermore, rotormills are effective at drying slurries from wet mills, as the suspension can be directly injected into the grinding chamber.

Technological Advancements in Rotormills

Over the last few decades, significant advancements in rotormill technology have enhanced their efficiency, flexibility, and overall performance.

Key innovations in rotormill technology include:

• Energy Efficiency: Modern rotormills are engineered to optimize energy consumption and improve motor performance, thereby reducing operational expenses.
• Modular Design: Specialized rotor configurations enable straightforward replacements, increasing versatility. Modular designs may soon be adopted for other critical components as well.
• Quieter Operation: Enhanced rotor balancing minimizes vibrations, leading to quieter machinery and reduced wear over time.
• Increased Durability: Advanced construction materials and coatings protect rotors and blades, particularly when dealing with abrasive substances.

Applications of Rotormills

Rotormills serve as versatile tools for transforming various materials into fine powders. They accommodate fibrous, hard, soft, and temperature-sensitive materials, catering to numerous industries. Commonly processed materials include activated charcoal, fertilizers, plant matter, plastics, powder coatings, seeds, straw, tobacco, wood, and more.

Rotormills find application in multiple processing scenarios, such as:

• Agriculture: Ensuring uniformity in animal feed ingredients and additives.
• Chemicals: Breaking down chemical powders used in fertilizer and resin production.
• Cosmetics: Converting raw materials into fine powders for personal care products.
• Food Processing: Milling grains, spices, and sugar to achieve consistent quality.
• Metal Powders: Reducing metallic materials into fine powders.
• Minerals: Crushing substances like coal, gypsum, limestone, quartz, silica, and talc.
• Pigments: Producing fine powders for paints and pigments.
• Pharmaceuticals: Grinding active and inactive ingredients for medications, including capsules, tablets, and emulsions.
• Plastics: Reducing plastic pellets for manufacturing purposes.
• Recycling: Processing waste materials like plastics and elastomers.

Typically, rotormills can adapt to different processes and speeds, with most of their electronic components enclosed to shield them from dust infiltration.

Prater's Rotor Mills

The Rotormill, manufactured and marketed by Prater Industries, was originally developed by IPEC (International Process Equipment Company) and acquired by Prater in 2021. The signature Rotormill provides bulk processors with a method to mill materials finely and continuously at high throughput rates. Prater's version of the rotor mill also performs exceptionally well with abrasive and softer materials. It can even coat and mix simultaneously, offering processors increased flexibility.

All Rotormills boast compact yet robust construction, adjustable intake ports for airflow, and easy access to the interior for maintenance purposes. For more information about Prater's various Rotormill models, please contact one of our sales representatives today.