How Material Size Directly Affects Size Reduction Energy
March 25, 2015
Brian L. List
This is a study of how the size of the starting material can influence the processing rate, tightness of the particle size distribution, and energy costs associated with particle size reduction.
There are many reasons to pursue jet milling as part of your size reduction plan. These advantages include: purity of product, continuous processing, dry processing, and the finest and narrowest particle size distribution (PSD). Jet mills are generally capable of reducing large feed stock of ½ in.1 down to below an average particle size of 5µm. The size of the feed stock is limited to what the feed funnel of the mill will accept as a free flowing material.
It may not be well known, but there are three physical laws that describe the energy required for size reduction. They are the Bond’s Law, Rittinger’s Law, and Kick’s Law. These laws provide a relative approach to looking at the materials being reduced and do not include equipment efficiency or material friability characteristics.
Bond’s Law: The work required to form particles from very large feed is proportional to the square root of the surface-to-volume ratio.