If the overall combustion performance, including NO_x, fineness, fuel distribution, LOI, and superheater slagging cannot be improved with ball charge changes, then consideration should be given to the installation of static-centrifugal classifiers. These classifiers provide the appropriate capability to achieve desired fuel fineness levels. A static-centrifugal classifier functions not only as a classifier but also homogenizes the fuel distribution from pipe to pipe. This mixing function is equally important as coarse particles return to the pulverizer.  STORM^® designed static classifiers are field-proven on Ball Tube and Attrita type mills. In many plants, they offer the most technically feasible solution, compatible with burner and other reduced NO_x changes.