A: Suha Ozsoylu, Hosokawa Micron Powder Systems, says:
Numerous size reduction systems and solutions are available for processing dry bulk materials, but often only a few can efficiently and effectively produce your desired results. Here are some questions to consider when you’re researching size reduction equipment:
- What’s your feed material’s maximum particle size? This will help narrow your equipment candidates. For example, particles larger than 500 microns will be difficult to feed into a spiral jet mill without causing plugging.
- What’s your required particle size distribution (PSD)? Do you have a single target point such as the mean particle size, or do you also have limitations on the PSD’s upper and lower end? For example, if you have a target particle size, a pin mill or a spiral jet mill probably won’t be suitable because both lack an internal classification mechanism and would produce wider PSDs. And if your top size requirement is less than 10 microns, your options will be limited to jet mills or media mills.
- What are your material’s characteristics? Is the material cohesive, abrasive, hygroscopic, heat-sensitive, fibrous, or crystalline? Not all size reduction equipment can handle each of these characteristics. For example, mills with internal screens might not be suitable for grinding cohesive powders, and impact mills with low airflow aren’t suitable for grinding heat-sensitive materials.
- What are your other requirements? Do you require equipment that can recover product, that’s easy to clean, or that must meet space or power restrictions? For example, certain mills are easier to clean than others: A spiral jet mill has no moving parts and a simple cylindrical housing that’s very easy to clean, but a media mill is a more complicated piece of equipment and harder to clean quickly.
These questions are a good place to start when you’re starting to select size reduction equipment. Once you get beyond the basics, the most efficient and cost-effective solution is to work with a manufacturer that carries a wide range of equipment, has plenty of experience, and can test the milling equipment with your material and under your process conditions and provide a detailed analysis of the results.
Hosokawa Micron Powder Systems, Summit, NJ, designs and manufactures size reduction, classification, and mixing equipment for the chemical, pharmaceutical, and food industries.