Advice from Union Process on finding the right grinding mill for chemicals

Firing Industries is Canada’s provider of processing equipment by Union Process (UP), world-famous for grinding attritors. A recent issue of Chemical Processing featured an article by UP national sales manager Robert E. Schilling, about how to choose the right grinding mill for chemical-processing applications. Among his key points for chemical businesses is to consider both the nature of the feed material and the objective of the milling task.

A role in three areas

Milling typically refers to reducing materials to sizes in the low micron or nano-size range. Chemical operations often need extremely fine materials. According to UP, media milling technology plays a substantial role in three areas of this sector: particle-size reduction of chemicals; mixing chemicals to make new compounds; and activation or liberation of chemical raw materials. Customers can choose from different types of mills for these applications: ball, attrition, sand, or small-media mills.

Different mills suit different processing requirements, Schilling explains. An important factor in the process of selecting a grinding mill is the feed material. Customers should consider four aspects: whether the material is friable, fibrous, heat-sensitive, or sticky; the feed particle’s shape; the hardness and abrasiveness of the material; and the desired size. In addition, customers should consider the material of construction and what duties the mill will perform.

Schilling recommends dry grind processing for products with particle-size specifications of two to three microns average or larger. Cost savings are a significant advantage of dry grinding, and UP attrition mills from Firing Industries can operate in either batch or continuous mode and suit hard-to-grind material. For particle sizes below three microns, wet milling is preferable. Wet grind processing can be performed in batch, continuous, or circulation modes. High circulation mills for wet grinding are common with paint and mill manufacturers.

Selection of grinding media also depends on many factors, like specific gravity, initial feed size, final particle size, hardness, pH, discoloration, contamination, and cost. Attrition milling requires media sizes from 1/8 to 3/8 of an inch; smaller media typically begets faster reduction.

To learn more, contact Firing Industries’ application-sales engineers at or (877) 688-0974.

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