Latest developments in cyclone technology

Abstract

Although cyclones have been around in their current form since the early 1890s, there have been some exciting new developments, which have extended their efficiency/operation. These developments have taken place with both dense medium and classification cyclones. The more noteworthy developments are inlet design, secondary offtake, water injector, 3 in 1 cyclone, and the Rejector.

Inlet design is the determining factor in classification cyclone capacity and efficiency. The recently developed ribbon inlet with patented pressure bulge has not only resulted in increases in capacity, but also in efficiency. Sharpness of separation corresponding to an alpha value of greater than 4 has been achieved.

One of the factors leading to reduced cyclone efficiency is the presence of coarse particles in the cyclone overflow. The secondary offtake has been developed specifically to scavenge these particles from the cyclone overflow with great success. The other major factor resulting in reduced cyclone efficiency is the presence of misplaced fine particles in the cyclone underflow. The water injector, which has been around for many years in various forms, can reduce this short circuit fraction by up to 50%. The 3 in 1 cyclone combines the inlet design, secondary offtake and water injector into a single unit resulting in the most efficient classification cyclone available in the market.

Iron ore has a high yield to underflow and traditional dense medium cyclones have always been spigot constrained. The Rejector is an exciting new development whereby the spigot capacity has been increased substantially. The application of the Rejector results in fewer/smaller cyclones being required for a given duty resulting in efficiency gains and reductions in both operating and maintenance costs.