Step Grind For Efficiency in the U.S.

Since corn, wheat, sorghum and barley are the basis for most complete feeds in the U.S., the primary economic benefit of step grinding is an actual reduction in the specific energy required to grind feed materials rather than efficiency gains from sifting. As a rule of thumb for a two shift operation, one horsepower costs approximately $1.00 per day. An energy reduction of 50 horsepower will save about $50.00 per day in energy expenditures. Where does this savings come from? Power consumption can be expressed in terms of work accomplished over time.

The step grind approach yields this energy reduction (less power required) since the materials are reduced more gradually, through a slightly longer period of time. By doing the same amount of work (grinding) over a longer period of time (two or three gradual reductions instead of one instantaneous reduction) the total power requirement is reduced.

Because the roller mill offers such significant energy savings over a hammermill when processing grain in the coarser particle size ranges, the use of the roller mill as a pre-break device can offer substantial savings in a typical grain grinding circuit. By substituting a single pair roller mill in place of the conventional hammermill rotary feeder, the feed rate can be accurately controlled and a significant increase in hammermill capacity can be realized. Because the materials are reduced in size prior to being introduced to the hammermill grinder, larger screens may be employed with no significant increase in finished particle sizing.

This combination of finer feed, increased hammermill efficiency, and the possible use of larger screens not only reduces the energy cost when grinding, but reduces other operating costs (maintenance, parts) as well. Since a rotary feeder is not required the cost of a roller mill for use as a feeder is substantially offset in new installations. In other cases where existing hammermills require a boost in capacity, the application of a roller mill as a feeder can boost hammermill capacity by as much as 40 to 50% with no loss in the fineness of the grind.