SINGLE-PASS THREE-STREAM COAL SEPARATION
Three Product Cyclone for Coal Washery Middlings Separation
John Finlay’s Three Product Cyclone separates coal slurry into clean coal, middlings, and reject in a single unit and a single pass engineered for washeries handling difficult, high-near-gravity Indian coal that would otherwise need a second cyclone stage.
DSM Geometry
Design Basis
DEFINITION & OVERVIEW
What is a Three Product Cyclone in a Coal Washery?
A three product cyclone is a heavy medium separation cyclone that produces three discrete output streams clean coal, middlings, and reject, from a single feed and a single pass, rather than the two streams a standard heavy medium cyclone produces.
In a conventional two-product HM cyclone circuit, coal with a substantial near-density middlings fraction typically needs a second cyclone stage to separate that middlings material from the clean coal product. John Finlay’s Three Product Cyclone removes that second stage by adding a dedicated intermediate outlet positioned between the primary underflow and the overflow, drawing off near-density material before it reaches either end product.
The design is a proprietary intermediate-outlet design manufactured at John Finlay and built on Dutch State Mines (DSM) cyclone geometry, the design foundation underlying the wider heavy-medium cyclone family across the industry.
How It Works
Tangential feed entry generates centrifugal separation across three density bands in a single pass, discharging clean coal, middlings and reject from dedicated outlets.
Patented Design
Covered by patents cited on John Finlay's Group of Companies page, built on proven DSM cyclone geometry.
Role in DMS Circuit
Removes the need for a second-stage cyclone to isolate middlings, simplifying circuit layout for difficult-washing coal.
Key Performance Data
Parameter | Value |
|---|---|
Diameter Series | 1000mm – 1500mm |
Feed Size | Up to 110mm |
Capacity Range | 160–650 t/h |
Medium Circulation | 600–1500 m³/h |
Working Pressure | 0.13–0.50 MPa |
Medium-to-Coal Ratio | 2.5:1 (easy washing) – 3.5:1 (difficult washing) |
KEY FEATURES
Key Features & Performance Highlights
John Finlay's Three Product Cyclone is built for washeries that need dedicated middlings handling without adding a second processing stage.
Single-Pass Three-Product Separation
Clean coal, middlings and reject are separated in one cyclone body and one pass through the intermediate outlet draws off near-density material that a standard two-product cyclone would otherwise pass through to the overflow or underflow, where it would need a second stage to isolate.
DSM-Based Cyclone Geometry
Built on Dutch State Mines cyclone geometry, the design foundation used across the heavy medium cyclone industry, adapted here to support a third, independently controlled outlet stream.
Full Diameter Series for Scalable Throughput
Available across a 1000mm to 1500mm diameter series, covering capacity requirements from 160 t/h up to 650 t/h, so the unit can be matched to washery throughput rather than oversizing or undersizing a single fixed design.
Working Principle
How a Three Product Cyclone Works in Coal Preparation
Understanding the working principle helps coal washery engineers evaluate whether a three product cyclone fits a given washability profile.
Technical Specifications
Three Product Heavy Medium Separation Cyclone | Full Specification Table
Specifications sourced directly from John Finlay’s cyclone technical documentation, covering the full diameter series.
| Model (Dia./Spigot mm) | Feed Size | Working Pressure | Medium Circulation | Capacity |
|---|---|---|---|---|
| 1500 / 1060 | ≤110mm | 0.30–0.50 MPa | 1300–1500 m³/h | 500–650 t/h |
| 1400 / 1000 | ≤100mm | 0.28–0.40 MPa | 1200–1400 m³/h | 400–550 t/h |
| 1200 / 850 | ≤ 85 mm | 0.20–0.28 MPa | 900–1200 m³/h | 250–380 t/h |
| 1000 / 700 | ≤75mm | 0.13–0.20 MPa | 600–800 m³/h | 160–250 t/h |
COMPARISON
Three Product Cyclone vs Standard Two-Product Cyclone
Three Product Cyclone (John Finlay)
Standard Two-Product Cyclone
Applications of the Three Product Cyclone in Coal Washing
The Three Product Cyclone is most valuable wherever a washery's coal has enough near-density middlings material to justify dedicated handling.
Coking Coal Washeries
Difficult-to-wash coking coal with a high near-gravity material fraction benefits most from single-pass middlings isolation.
Circuit Simplification
Replaces a two-stage cyclone setup with one unit, reducing equipment count, footprint, and maintenance points.
Middlings-Heavy Coal Seams
Seams that consistently produce a significant middlings fraction get dedicated handling without extra processing steps.
New Washery Design
Reduces capex and civil footprint compared to specifying a full second cyclone stage for middlings duty.
Retrofit Upgrades
Can replace an existing two-product cyclone stage where a plant is adding dedicated middlings handling.
High Near-Gravity Indian Coal
Indian coking coals with high NGM content are exactly the washability profile this design was built for see our blog on magnetite granulometry for the related cut-point discussion.
About John Finlay
Three Product Cyclone Supplier in India
Why John Finlay?
Three Product Cyclone | Frequently Asked Questions
Common questions from coal washery process engineers evaluating three product cyclone technology.
A three product cyclone separates coal slurry into three discrete streams clean coal, middlings, and reject in a single pass, using a dedicated intermediate outlet. A standard heavy medium cyclone produces only two streams (product and reject), requiring a second cyclone stage if the coal has a middlings fraction that needs separate handling.
Coal slurry enters tangentially under pressure, generating centrifugal force. Heavier reject material moves to the primary underflow, medium-density middlings are drawn off through a dedicated intermediate outlet, and the lightest clean coal rises to the overflow, all in one cyclone body.
Selection depends on your required throughput and feed top size. John Finlay’s series ranges from 1000mm diameter (160–250 t/h, feed up to 75mm) to 1500mm diameter (500–650 t/h, feed up to 110mm). Contact our engineers with your washability data and target throughput for correct sizing.
The Three Product Cyclone is manufactured at John Finlay’s Hefei, China, facility, part of the John Finlay Group’s in-house manufacturing operation for process equipment that supplies coal washeries in India and internationally.
Need Help Selecting the Right Cyclone Configuration?
Our experts can help you evaluate whether a three-product cyclone fits your washability profile and throughput requirements.
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