Thickener Capacity Calculator
Thickener area is governed by how fast solids settle, expressed as a unit area loading or solids flux in tonnes of dry solids per square metre per hour (t/m²/h).
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- To size a new thickener, enter the solids throughput (t/h) and the unit area loading (solids flux, t/m²/h) from settling testwork — the tool returns the required settling area and diameter.
- To check an existing unit, leave throughput blank, enter the unit area loading and the existing thickener diameter (m), and read off the solids capacity in t/h and t/day.
- Take the unit area loading from batch or flux (Coe & Clevenger / Talmage & Fitch style) settling testwork on the actual slurry — do not guess it.
How it works
Thickener area is governed by how fast solids settle, expressed as a unit area loading or solids flux in tonnes of dry solids per square metre per hour (t/m²/h). The required clarification/thickening area is the solids throughput divided by that loading: A = throughput (t/h) ÷ unit loading (t/m²/h). A circular thickener of that area has diameter D = √(4A ÷ π).
Run in reverse, an existing thickener of diameter D has area A = π(D/2)² and a solids capacity of A × unit loading (t/h). This is a first-pass sizing check only: it ignores feedwell dilution, rake torque, underflow density, flocculant performance and turn-down, all of which real thickener design must account for from testwork.
Worked example
Sizing a thickener for 60 t/h of solids. A concentrator feeds 60 t/h of dry solids to a thickener and flux testwork gives a unit area loading of 0.25 t/m²/h. Required area = 60 ÷ 0.25 = 240 m². Diameter = √(4 × 240 ÷ π) = 17.48 m, so an 18 m thickener comfortably covers the duty with a small margin.
Common mistakes
- Confusing volumetric flow with solids mass — the unit area loading is dry solids per m² per hour (t/m²/h), not slurry volume; feeding slurry m³/h into it gives a nonsense area.
- Guessing the unit area loading instead of taking it from settling/flux testwork on the real slurry — settling rate depends heavily on particle size, mineralogy and flocculant, so a wrong flux directly mis-sizes the tank.
- Sizing to the exact required area with no margin — sensible design adds turn-down/safety allowance and rounds up to a standard diameter, so 240 m² becomes an 18 m unit, not a bare 17.48 m.
Frequently asked questions
What unit area loading (solids flux) should I use?
There is no universal value — it must come from batch or continuous settling (flux) testwork on your actual slurry, since it depends on particle size, mineralogy and flocculant. Typical mineral thickeners run roughly 0.1–1.0 t/m²/h, but treat that only as a sanity band, not a design input.
Does this size the thickener depth or just the diameter?
Just the plan area and diameter, which set the settling/clarification duty. Sidewall depth (for compression, mud bed and rake clearance), feedwell design and rake torque are separate design steps and are not covered here.
Can I use it for a clarifier or tailings thickener?
Yes — the same area = throughput ÷ unit loading relationship applies to any gravity settling unit. Just make sure the loading value comes from testwork representative of that specific feed.
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