Module 1 · Hydrocyclone Fundamentals
03
Lesson 3 of 5

Components and Their Functions

Six parts, no motors. Each one exists purely to shape the flow — and each is a lever an operator can pull to change how the cut point behaves.

A hydrocyclone looks simple from the outside — a cylinder on top of a cone — but every component is doing specific hydraulic work. The numbers below correspond to the labelled cutaway in Fig. 3.1.

1

Feed chamber & inlet

Delivers the incoming slurry tangentially (or through an involute passage) against the cylinder wall, converting straight-line flow into rotational flow. Inlet geometry and diameter set the entry velocity, which strongly influences the cut point.

2

Cylindrical section

The upper body of the vessel. It stabilises the incoming spiral into a uniform rotating flow before the slurry reaches the narrowing cone. Longer cylindrical sections generally increase residence time and improve classification sharpness.

3

Vortex finder

A pipe extending down into the cylinder from the top, open at the bottom, sealed from the feed chamber at the top. It captures the inner, ascending vortex and channels the fine-particle overflow out of the unit. Its diameter is one of the primary controls over the d50 cut point — a smaller vortex finder pushes the cut finer.

4

Conical section

The tapering lower body. As the diameter shrinks, rotational velocity increases, intensifying the centrifugal force applied to particles. The cone angle governs residence time and capacity — a longer, shallower cone gives a sharper but lower-capacity separation.

5

Apex (spigot)

The small opening at the very bottom of the cone where the coarse underflow discharges. Apex diameter is the single most-adjusted component in daily operation — a partly worn or incorrectly sized apex is the most common cause of a cyclone "roping" (see callout below).

6

Wear liner

A replaceable inner lining — commonly rubber, polyurethane, or ceramic — protecting the cone and apex from the abrasive slurry. Because the vessel has no moving parts, the liner is almost the only component that wears out, and it is sized for scheduled replacement rather than repair.

Roping vs. spraying: underflow should exit the apex as a thin, umbrella-shaped spray. If the apex is too small (or worn shut, or overloaded with coarse solids) it instead discharges as a dense, rope-like stream — a sign that coarse material is being carried into the overflow, ruining the separation. Operators watch the underflow discharge shape as a quick visual health check.
Key Takeaways
  1. Every component shapes the flow hydraulically — there is no electrical or mechanical control inside the vessel itself.
  2. The vortex finder and apex are the two components operators change most often to shift the cut point.
  3. The wear liner is the only routinely replaced part, since the vessel body itself has no moving components to fail.
  4. Underflow discharge shape (spray vs. rope) is a fast, practical diagnostic of whether the apex is correctly sized for current conditions.