The objective of all silo designs is to obtain reliable and controllable flow of particulate solids in such processes. However, the fact is that various problems in solids flow occur very frequently in many solids handling processes. These are mainly dominated by material arresting, flooding or segregating, briefed as follows.

• No flow takes place when the outlet of the silo is opened. A stable arch that prevents flow is formed above the outlet. This may happen both with fine powders and coarse solids, and is generally attributed to the development of cohesion in the solids or to mechanical interlocking;
• The flow stops after a while. Only the solids which are located vertically above the outlet flow out while the remaining solids (material in the dead zones) form stable vertical walls thus creating a ‘rat-hole’ or ‘pipe’; or
• The flow stream is erratic, very unstable or even flooding.

These phenomena usually cause economic losses, which are sometimes far in excess of the cost of the silo facility itself. Most of the problems can be avoided with a proper silo design. Contact us on how to design a silo based on powder mechanics (mainly measurement results of flow properties) for secure flow and complete emptying.

Fig. Silo problems