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Hydrometallurgy

Thickener Solids Loading Rate Calculator

This calculator estimates how hard an existing thickener of known diameter is being pushed: it computes the cross-sectional area from the diameter, the unit-area solids loading rate (t/m²/day) from the dry solids throughput, and — if an overflow flow is given — the hydraulic rise/overflow rate (m/h). It is an operating check for a thickener of known diameter only. It is NOT a thickener sizing, selection, or design tool, and it is NOT a settling-flux calculation. It does not predict overflow clarity, bed depth, flocculant demand, rake torque, underflow density, or throughput limit. Thickener sizing requires settling/flocculation testwork (e.g. Coe-Clevenger, Talmage-Fitch), rheology, design margins, and qualified review, and is out of scope here.

TypeInteractive engineering calculator

Calculator

t/h

dry solids basis

m

known operating diameter

Optional

m³/h

clarified overflow, for rise rate

Result
Thickener area962.113 m²
Solids loading rate2.99341 t/m²/day
Overflow / rise rate0.311814 m/h
  • !Operating check for a thickener of KNOWN diameter only — NOT a thickener sizing, selection, or design tool.
  • !Not a settling-flux calculation. Does not predict overflow clarity, bed depth, flocculant demand, rake torque, underflow density, or throughput limit. Sizing requires settling/flocculation testwork (e.g. Coe-Clevenger, Talmage-Fitch) and qualified review.

Formulas

Thickener area
A = π × D² / 4
Solids loading rate
loading = ṁ_solids × 24 / A
Overflow / rise rate
rise = Q_overflow / A

Diagram

Thickener solids loading rate — loading = solids × 24 / area; rise = overflow / areaDarea = πD²/4solids t/hloading = ṁ_solids × 24 / Arise = Q_overflow / Aoperating check —not a sizing tool

Worked example

A thickener of 35 m diameter treats 120 t/h dry solids, with a clarified overflow flow of 300 m³/h.

  1. 01Area: π × 35² / 4 = π × 1225 / 4 = 962.11 m²
  2. 02Solids loading: 120 × 24 / 962.11 = 2880 / 962.11 = 2.99 t/m²/day
  3. 03Overflow / rise rate: 300 / 962.11 = 0.31 m/h
  4. 04Compare against typical operating ranges as a check, not a sizing result
Result

Area 962.11 m², solids loading 2.99 t/m²/day, overflow/rise rate 0.31 m/h — an operating check, not a sizing.

FAQ

Can I use this to size a new thickener?
No. This is an operating check for a thickener whose diameter you already know. Sizing a new thickener requires settling/sedimentation testwork (Coe-Clevenger, Talmage-Fitch), flocculant selection, underflow rheology, and design margins — none of which this computes.
What does the solids loading rate tell me?
It tells you the dry-solids mass loaded per square metre of thickener area per day at the current throughput. It is useful as an operating check against typical ranges, but it is not a settling-flux limit or a guarantee of performance.
What is the rise (overflow) rate?
The clarified overflow volumetric flow divided by the thickener area, giving an upward velocity in m/h. Like the loading rate, it is an operating context figure, not a clarity or capacity guarantee.
Why is the overflow flow optional?
The solids loading rate needs only the throughput and diameter. The rise/overflow rate additionally needs the overflow flow, so it is computed only when you supply that input.

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