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Hydrometallurgy

CCD Wash Water Calculator

In a counter-current decantation (CCD) circuit, wash water is added against the flow of thickened solids to displace soluble values from the underflow liquor. This calculator estimates the wash-water flow needed to hit a target wash ratio, working from the dry solids rate and the underflow solids concentration to find the liquor carried with the underflow. It is a wash-water / wash-ratio estimator only — it is NOT a CCD soluble-recovery model and does not predict stage efficiency or solution tenor.

TypeInteractive engineering calculator

Calculator

t/h

dry solids basis

wt%

0–100 wt% solids by mass

kg/m³

underflow liquor density

—

wash water ÷ underflow liquor

Optional

m³/h

for actual wash-ratio check

Result
Underflow slurry mass181.818 t/h
Underflow liquid mass81.8182 t/h
Underflow liquid volume81.8182 m³/h
Required wash water flow163.636 m³/h
Actual wash ratio1.95556
  • !Actual wash ratio is below the target — the existing wash water flow is less than the required flow.
  • !Wash-water / wash-ratio estimate only — this is NOT a CCD soluble-recovery model. It does not predict recovery, stage efficiency, or solution tenor.

Formulas

Underflow slurry mass
ṁ_slurry = ṁ_solids / (wt% / 100)
Underflow liquid mass
ṁ_liquid = ṁ_slurry − ṁ_solids
Underflow liquid volume
Q_liquid = ṁ_liquid × 1000 / ρ_liquid
Required wash water
Q_wash = wash_ratio × Q_liquid
Actual wash ratio
ratio = Q_wash,existing / Q_liquid

Diagram

CCD wash water — wash ratio = wash water flow / underflow liquor flowCCD1CCD2CCD3solids + underflow liquor →← wash waterwash ratio = Q_wash / Q_underflow liquorwash-water estimate — not soluble recovery

Worked example

A CCD circuit treats 100 t/h dry solids at 55 wt% underflow solids with liquor density 1000 kg/m³. Target wash ratio 2.0, existing wash water 160 m³/h.

  1. 01Underflow slurry mass: 100 / (55 / 100) = 181.82 t/h
  2. 02Underflow liquid mass: 181.82 − 100 = 81.82 t/h
  3. 03Underflow liquid volume: 81.82 × 1000 / 1000 = 81.82 m³/h
  4. 04Required wash water: 2.0 × 81.82 = 163.64 m³/h
  5. 05Actual wash ratio at 160 m³/h: 160 / 81.82 = 1.96
Result

Underflow slurry 181.82 t/h, liquid 81.82 t/h, liquid volume 81.82 m³/h, required wash water 163.64 m³/h, actual wash ratio ≈ 1.96.

FAQ

Is this a CCD recovery model?
No. It estimates the wash-water flow for a target wash ratio and the liquor carried with the underflow. It does not predict soluble recovery, stage efficiency, or wash loss — those require a soluble balance and testwork.
What is the wash ratio here?
The simple definition used by this calculator is wash-water volume flow divided by the underflow liquor volume flow. A higher wash ratio means more wash water relative to the liquor carried with the solids.
Why does underflow solids concentration matter?
It sets how much liquor is carried with the thickened solids. Thicker underflow carries less liquor per tonne of solids, reducing the liquor that the wash water has to displace.
Does more wash water always mean better recovery?
Not automatically. Wash ratio is one lever, but recovery also depends on stage count, mixing, entrainment, and thickener performance. More wash water dilutes the product solution and has practical limits, so the final design comes from a soluble balance and modelling.

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