Small diameter (1'' - 2'') hydrocyclones are used in different applica
tions, in industrial minerals processing and in desliming ahead of flo
tation. The study of hydrocyclone performance, in terms of both fundam
ental and operational variables, has been undertaken by several author
s. Empirical models are used for predicting the hydrocyclone performan
ce in terms of capacity, cut size (d50c), water split and partition cu
rves. However, these models have been developed for larger hydrocyclon
es, while for smaller cyclones little modelling has been done. Only a
few previous studies exist, which propose either new model equations o
r modifications to the existing ones. This paper reports experimental
research on small hydrocyclones. The suitability of existing models ha
s been checked and their accuracy compared. The experimental results s
how, in some aspects, coherency with what is already known. In other a
spects, the results are in disagreement with previous findings. Accord
ingly, new model equations are proposed, which improve the predictive
capability for small hydrocyclone performance.