The core principle of a water-jacketed centrifugal concentrator (Nelson centrifuge) is to achieve efficient separation of high-density fine minerals (such as gold) from low-density gangue by using backwash water to form a dynamic fluidized bed in a strong centrifugal force field.
I. Core Structure (Key Components)
Double-layer drum (core):
Inner layer: A stainless steel cone with annular spacers, its walls densely perforated to form enrichment tanks.
Outer layer: Forms a closed water jacket with the inner layer, used for distributing backwash water.
Hollow main shaft: Pressurized water enters the water jacket through this shaft and is then ejected from the small holes in the inner layer.
Drive system: A motor drives the drum to rotate at high speed (150–500 rpm), generating a centrifugal force of 60–100g.
II. Working Process (Detailed Explanation of Four Steps)
Feeding and Centrifugal Settling
The slurry is fed into the bottom of the drum from the center. Under the action of strong centrifugal force, the slurry flows upward along the cone wall. High-density particles (such as gold) are subjected to greater radial force, rapidly thrown towards the inner wall and deposited within the annular spacer trough; low-density gangue moves upward with the water flow.
Backwash Water and Fluidization (Critical Stage)
Pressurized water (0.03–0.06 MPa) enters the water jacket through the hollow shaft and is ejected upward from the inner pores, forming a backwash upward flow opposite to the centrifugal force.
The backwash water fluidizes the mineral layer within the spacers, forming a dynamic separation bed.
High-density minerals: Centrifugal force >> water flow resistance → remain stably at the bottom of the trough.
Low-density gangue: Centrifugal force < water flow resistance → continuously flushed upward.
Continuous Separation and Tailings Discharge
Light minerals overflow from the top of the drum with the upward water flow and enter the tailings trough; heavy minerals continuously accumulate and displace within the spacers, forming a concentrate layer.
Concentrate Discharge (Intermittent/Automatic)
After a period of operation, stop the machine or switch the water flow direction to flush out the concentrated heavy minerals (concentrate) in the diaphragm using high-pressure water.
III. Principle and Essence (Summarized in one sentence)
Centrifugal force amplifies density differences, and backwash water dynamically screens the particles; heavy minerals "settle and accumulate at the bottom," while light minerals "float and are discharged," achieving efficient recovery of fine particles.
