Working Principle of the Centrifugal Concentrator

Separation in a centrifugal concentrator relies on fluidization mechanics inside a rotating ribbed cone:

1. High-G Centrifugal Field: Slurry enters centrally through the feed tube into the inner rotating bowl. The high-speed rotation generates an artificial centrifugal field 60 to 100 times greater than Earth’s gravity (G-force).
2. Pressurized Fluidization Water: Clear backwash water is injected through multiple fluidization holes drilled in the rings of the inner bowl. This upward water pressure keeps the trapped mineral bed loose and fluidized, preventing gangue compaction.
3. Selective Mineral Entrapment: Under combined centrifugal force and fluidizing water, high-density gold particles (specific gravity 15–19) overcome water drag and penetrate deep into the retention grooves. Lower-density gangue minerals (specific gravity ~2.6–3.0) cannot penetrate the fluidized bed and are continuously carried upward to the tailings overflow.
4. Concentrate Discharge:
   • Batch / Semi-Continuous Type (STL Series): After operating for a predetermined cycle (typically 1–4 hours for placer gold, 30–60 minutes for grinding circuit feeds), feeding stops, the bowl slows down, and concentrated gold is flushed out through the bottom discharge port.
   • Fully Automatic PLC Type: Automation valves control washing, feeding, stopping, concentrate dumping, and rinsing sequences without manual intervention.

Technical Specifications (LIPU STL Series)

Model	Feeding Capacity (Dry Solids)	Slurry Capacity	Max Feed Particle Size	Optimal Recovery Size Range	Slurry Density (Solids %)	Fluidization Water Pressure	Fluidization Water Consumption	Motor Power
STL-20	0.5 – 2 t/h	2 – 4 m³/h	0 – 3 mm	0.02 – 1.5 mm	20% – 40%	0.10 – 0.20 MPa	2 – 3 m³/h	1.5 kW
STL-30	3 – 5 t/h	5 – 10 m³/h	0 – 4 mm	0.02 – 2.0 mm	20% – 40%	0.15 – 0.25 MPa	3 – 5 m³/h	3.0 kW
STL-60	10 – 15 t/h	15 – 25 m³/h	0 – 5 mm	0.02 – 2.5 mm	20% – 45%	0.15 – 0.30 MPa	8 – 12 m³/h	7.5 kW
STL-80	20 – 30 t/h	30 – 45 m³/h	0 – 5 mm	0.015 – 2.5 mm	20% – 45%	0.18 – 0.35 MPa	15 – 20 m³/h	11.0 kW
STL-100	40 – 60 t/h	60 – 90 m³/h	0 – 6 mm	0.010 – 2.5 mm	20% – 45%	0.20 – 0.40 MPa	25 – 35 m³/h	18.5 kW
STL-120	80 – 120 t/h	120 – 160 m³/h	0 – 6 mm	0.010 – 2.5 mm	25% – 50%	0.25 – 0.45 MPa	45 – 60 m³/h	30.0 kW

Note: Clean fluidization water is required (suspended solids < 50 ppm) to avoid clogging water injection orifices.

Core Engineering Advantages

• Superior Recovery of Ultrafine Gold: Traditional sluice boxes lose gold finer than 100 mesh (150 µm). LIPU centrifugal concentrators reliably recover liberated particles down to 10–20 µm.
• Variable Frequency Drive (VFD): Allows stepless bowl rotation speed control to dial in exact G-force according to specific ore weight and particle liberation.
• Wear-Resistant Polyurethane & Stainless Steel Components: Inner ribbed bowls are fabricated from high-grade polyurethane or wear-hardened stainless steel, offering extended operating life in abrasive slurries.
• One-Touch PLC Automation Option: Automated pneumatic pinch valves control the entire cycling, rinsing, and concentrate collection process with minimal operator oversight.
• Chemical-Free, Eco-Friendly Operation: Pure physical gravity beneficiation with zero cyanide or mercury, providing high-grade concentrate directly to melting or shaking table cleaning.

Applications Across Ore Processing Circuits

1. Grinding Circuit Gravity Trap (Hard Rock Gold)

Positioned on the hydrocyclone underflow or ball mill discharge. Recovers liberated coarse and fine free gold early in the comminution circuit, preventing gold overgrinding and reducing subsequent flotation reagent demand or cyanide consumption.

• Learn about Hard Rock Gold Processing Plants

2. Placer & Alluvial Gold Operations

Installed after trommel scrubber screening. It treats the screen undersize (typically -2 mm to -5 mm) as a primary rougher or scavenger, replacing or upgrading traditional sluice circuits.

• Explore Alluvial Gold Plant Solutions

3. Tailings Retreatment & Scavenging

Recovers escaped fine gold from historical flotation tailings, gravity tailings, or heap leach residue streams before final tailings dry stacking.

Typical Flowsheet Configuration

• Feed Preparation: Slurry feed is screened to minus 5 mm and conditioned for uniform feeding.
• Centrifugal Separation: Feed enters the LIPU Gold Centrifugal Concentrator operating under controlled backwash fluidization water pressure.
• Tailings Handling (Overflow): Overflow discharges continuously to hydrocyclone dewatering units and proceeds to flotation or leaching (CIL/CIP) circuits.
• Concentrate Upgrading (Underflow): High-grade gold concentrate flushes periodically to a finishing shaking table, producing direct smelting-grade gravity concentrate.

Frequently Asked Questions (FAQ)

What is the minimum particle size a centrifugal concentrator can recover?
With proper fluidization water pressure and slurry control, LIPU centrifugal concentrators effectively capture liberated free gold down to 10–20 microns (approx. 625–1250 mesh), which cannot be recovered by conventional jigs or sluice mats.

Why is backwash fluidization water necessary?
Without fluidization water, dense solids would quickly compact against the cone wall, eliminating the grooves and allowing fine gold to be washed away with tailings. Water injection keeps the bed fluid and porous, allowing heavy gold to continuously displace lighter gangue particles.

How often should the concentrate be discharged?
For alluvial gold with high grades of free coarse gold, concentrate discharge is recommended every 1 to 4 hours. In closed grinding circuits where heavy minerals (pyrite/magnetite) quickly saturate the grooves, shorter cycle times of 30 to 60 minutes are common.

What water quality is required for fluidization?
Clean, solids-free process water is essential. Water containing excessive coarse suspended solids will block the laser-drilled fluidization nozzles. LIPU supplies integrated inline backwash strainers/filters with each unit.