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Hydrometallurgy

CIL Tank Residence Time Calculator

A carbon-in-leach (CIL) circuit is a train of agitated tanks where leaching and carbon adsorption happen together. This calculator estimates the hydraulic residence time at a preliminary level — installed working volume from the tank count and working volume, an optional online tank factor, divided by the slurry flow — and, when a contextual carbon concentration is supplied, an order-of-magnitude carbon inventory. It is a hydraulic and inventory estimate only: it does not model gold adsorption, leach recovery, or carbon performance.

TypeInteractive engineering calculator

Calculator

m³/h

combined solids + liquid flow

tanks

whole number ≥ 1

m³

operating volume, not total

%

0–100% (optional, default 100)

Optional

kg/m³

contextual — for inventory estimate

%

optional contingency above nominal

Result
Installed working volume3600 m³
Effective online volume3600 m³
Nominal CIL residence time6 h
Residence time with margin6 h
Carbon inventory estimate54000 kg
  • !Hydraulic residence time and carbon inventory only — it does not predict gold adsorption or recovery. Confirm against metallurgical testwork.

Formulas

Installed working volume
V_installed = N_tanks × V_working
Effective online volume
V_online = V_installed × online% / 100
Nominal residence time
τ = V_online / Q_slurry
Carbon inventory
m_carbon = V_online × C_carbon

Diagram

CIL tank train — τ = V_online / Q_slurry, carbon inventory = V_online × CslurryCIL1CIL2CIL3CIL4τ = V_online / Q · carbon = V_online × C● activated carbon — inventory estimate only

Worked example

A CIL train is eight tanks, each 450 m³ working volume, fed with slurry at 600 m³/h. Online factor 100%, carbon concentration 15 kg/m³, design margin 0%. Estimate residence time and carbon inventory.

  1. 01Installed working volume: V = 8 × 450 = 3600 m³
  2. 02Online volume: 3600 × 100 / 100 = 3600 m³
  3. 03Nominal residence time: τ = 3600 / 600 = 6.0 h
  4. 04Carbon inventory: 3600 × 15 = 54,000 kg
Result

Installed volume 3600 m³, online volume 3600 m³, residence time 6.0 h, carbon inventory 54,000 kg.

FAQ

Is the carbon inventory a design figure?
No. It is an order-of-magnitude estimate from the online volume and the carbon concentration you enter. Real carbon inventory depends on the carbon management philosophy, adsorption profile, and operating practice.
How is CIL residence time different from leach residence time?
The hydraulic calculation is the same — online working volume divided by slurry flow. CIL adds activated carbon to the tanks so adsorption happens during leaching, which is why a contextual carbon-inventory estimate is included here.
Should I use slurry flow or solution flow for Q?
Use the slurry volumetric flow — the combined solids plus liquid flow through the tanks. Using the liquid flow alone overstates the residence time.
Does this model gold recovery?
No. It is a hydraulic and inventory estimate only. Adsorption, leach kinetics, and recovery come from testwork and circuit modelling, not from residence time alone.

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