The heavy medium cyclone is a coal preparation equipment featuring a simple structure, no moving parts, and high sorting efficiency. Since it lacks moving parts, the sorting process of the heavy medium cyclone hinges on the coordination of its own structural parameters and external operating parameters, which significantly differentiates it from other coal preparation methods.
During sorting, the material and suspension enter the heavy medium cyclone along the tangent at a certain pressure, generating a strong vortex flow. The liquid flow creates a descending outer spiral flow along the inner wall from the feed port and an ascending inner spiral flow near the axis. The inner spiral flow, due to negative pressure, inhales air, thus forming an air column at the axis. Clean coal is discharged from the overflow port along with the inner spiral flow, while gangue is discharged from the underflow port with the outer spiral flow.
The air column in the heavy medium cyclone forms because the underflow pipe and overflow pipe are connected to the atmosphere. The two - phase flow entering the cyclone moves in a strong spiral. When the tangential speed reaches the critical value, resistance at the outlets creates an internal rotating flow field and axial negative pressure. Air enters through the pipes and, with the joint action of axial negative pressure and fluid convection transmission, a through air column is formed.
When the particle density is greater than that of the suspension, the resultant force at radius r is positive, and the particle is propelled toward the outer spiral flow; otherwise, the particle is directed toward the inner spiral flow, thereby separating particles of different densities. The centrifugal force in the heavy medium cyclone is several to dozens of times greater than gravity, which greatly accelerates the sorting speed and enhances the sorting effect.
