It's the time that counts

Summary: Sieving is one of the oldest, but nonetheless still one of the most widely and frequently used technologies for the classification and characterisation of particulate systems. Comparison ("trial") of the particles of a polydisperse system against the apertures of a sieve mesh is a dynamic, and thus a highly time-related process. Sieves of various mesh sizes participate on a time-dependent basis in the sieving process when a multi-deck sieve system or a stack of analytical sieves is used.

1 Introduction

In the case of large mesh sizes, observation of sieve undersize against time indicated a change in the function curve only at the start of sieving. The plot is constant for longer times, with the result that no further sieve undersize occurs. A steadily rising function, dependent on particle size, was observed in the case of smaller mesh sizes. The sieving operation can be observed with good approximation as a process with first-order kinetics. A less pronounced dependence of the kinetics parameter is apparent in the case of longer times. A significant increase in probability of passage and in the kinetics of the spectrum of particles on the sieve surface was observed for shorter sieving times ....