Step Grinding, The European Approach

More than ten years ago, a step grinding system approach was being presented by European manufacturers of feed milling equipment as a means of reducing operating costs. An integral part of the European approach was sieving before grinding and sieving between grinding stages. Because the European feed manufacturer uses such a wide range of ingredients received in the form of a meal, there is a potential for a high percentage of the raw materials to already be an acceptable particle size for the feed manufacturing process.

By removing these sized materials, the load on the grinding equipment could be reduced considerably. It appears from research and testing in actual applications that the reduction in energy consumption is roughly equal to one half of the amount of the materials removed. In other words, removing 30% of the materials to be ground (as fines) and by-passing the grinder reduces the energy required to grind by about 15% (Figure 4 and Figure 5).