1. A HYDROCYCLONE IS JUST A GLORIFIED T-PIECE
Surprisingly, this is one of the top myths and interestingly from places you wouldn’t expect it. The cyclone, fortunately, is not just a T-piece, although you do get two products from it. Cyclones are designed to treat highly valuable products like those in diamond processing. In diamond operations, the DMS plant and its cyclone are one of the core items that will be checked for any reported product loss.
2. A HYDROCYCLONE IS THE PERFECT SEPARATOR
The meaning of a prefect separator is one that splits two products perfectly with no contamination of material to each other. Although a lot of effort goes into our designs and applications of hydrocyclones, this myth is busted.
Hydrocyclones, due to their nature, have material displaced to the overflow and underflow. However, this is offset by the ease of operation and relatively low cost. This diagram illustrates ‘perfect’ versus a cyclone separation.
3. A HYDROCYCLONE CAN GIVE A BONE-DRY UNDERFLOW
This myth is busted. We have received enquiries for hydrocyclones in series, and the assumption is that the underflow will become bone dry. Unfortunately, water adheres to the particles in the cyclone underflow and is not mechanically removed.
This is aggravated with finer particles where the relative surface area is increased. We receive enquiries for the replacement of thickeners. The hydrocyclone, in some applications, can replace thickeners but only in situations where the material is extremely coarse and the thickener poorly operated. With very fine material, a hydrocyclone’s limitation is that it is impossible to give a highly dense underflow as there is no mechanical means of removing or compressing out the water.
4. MILL CYCLONES GRIND
The myth is that in a closed ball mill circuit, the hydrocyclones do the grinding and by changing cyclones the grind can be altered drastically. This myth is unfortunately busted. If the cyclones are grossly off spec, they may affect the mill grind. The mills are responsible for the grind and the cyclones are responsible for classifying the oversize product to return to the mill and remove the correctly classified material. In many cases, the mill does not have sufficient energy or the means to grind the material.
5. CYCLONES CAN HAVE A CUT SIZE MEASURED IN MILLIMETRES
The myth is busted. Although hydrocyclones can treat particles measured in millimetre sizes, it does not mean that hydrocyclones have cut points measured in millimetres, but rather in microns (µm) and normally below 200 µm. For larger sizes, normal screening should be used.