Air classification — Part II, Performance and dynamics
Part I of this article [August 1987] discussed the main types of air classification equipment available on the market today. In addition, classifier applications were outlined and parameters for equipment selection, scaleup, and cost were reviewed. Part II presents formulas for measuring air classier performance and provides background information on particle and rotor dynamics. Process control concepts are also reviewed.
The performance of any classifier is measured in different ways. These include cutpoint, yield, circulating load, recovery, efficiency, and selectivity. Recovery and efficiency, while widely used, are not very accurate because only one screen size specifies the feed or products.