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Hydrometallurgy

Slurry Dilution Water Calculator

Diluting a slurry to a lower percent solids is done on a dry-solids basis: the solids stay constant and only the water changes. This calculator estimates the dilution water required to take a slurry from an initial wt% solids to a lower target wt% solids — the initial and target slurry and liquid mass flows, then the extra water in t/h and m³/h — using the same mass-balance engine as thickener feed dilution. It is a preliminary slurry dilution mass-balance estimate only. It is NOT a rheology, settling, or pipeline-transport model, and it does not model density non-ideality, entrained air, dissolved salts, mixing time, pumpability, or downstream thickener performance.

TypeInteractive engineering calculator

Calculator

t/h

dry solids basis (or batch t)

wt%

0–100 wt% solids by mass

wt%

must be lower than initial

kg/m³

dilution water density

Result
Initial slurry mass83.3333 t/h
Initial liquid mass33.3333 t/h
Target slurry mass125 t/h
Target liquid mass75 t/h
Dilution water required41.6667 t/h
Dilution water required41.6667 m³/h
  • !Preliminary slurry dilution mass-balance estimate only — target solids must be lower than the initial solids for dilution.
  • !Does not model density non-ideality, entrained air, dissolved salts, rheology, mixing time, pumpability, settling, or downstream thickener performance.

Formulas

Initial slurry mass
ṁ_slurry,i = ṁ_solids / (initial% / 100)
Initial liquid mass
ṁ_liquid,i = ṁ_slurry,i − ṁ_solids
Target slurry mass
ṁ_slurry,t = ṁ_solids / (target% / 100)
Target liquid mass
ṁ_liquid,t = ṁ_slurry,t − ṁ_solids
Dilution water (mass)
ΔW = ṁ_liquid,t − ṁ_liquid,i
Dilution water (volume)
ΔV = ΔW × 1000 / ρ_liquid

Diagram

Slurry dilution water — ΔW = solids × (1/Cw,target − 1/Cw,initial)initial %+ water+target %ΔW = solids × (1/Cw,target − 1/Cw,initial)a mass balance — not rheology or pumpability

Worked example

A slurry carries 50 t/h dry solids at 60 wt% solids and must be diluted to 40 wt% solids. Liquid density 1000 kg/m³.

  1. 01Initial slurry mass: 50 / 0.60 = 83.33 t/h
  2. 02Initial liquid mass: 83.33 − 50 = 33.33 t/h
  3. 03Target slurry mass: 50 / 0.40 = 125.00 t/h
  4. 04Target liquid mass: 125.00 − 50 = 75.00 t/h
  5. 05Dilution water: 75.00 − 33.33 = 41.67 t/h
  6. 06As a volume at 1000 kg/m³: 41.67 m³/h
Result

Initial slurry 83.33 t/h, target slurry 125.00 t/h, dilution water 41.67 t/h (≈ 41.67 m³/h).

FAQ

Why is slurry dilution based on dry solids, not a volume ratio?
Because the conserved quantity when you add water is the dry solids. Percent solids by mass tells you how much water accompanies each tonne of solids, so the dilution water is the change in water content at constant solids — a mass balance, not a C1V1 = C2V2 volume ratio.
How is this different from the generic dilution calculator?
The generic dilution tool works on a dissolved-species concentration and volume basis. This slurry version uses percent solids by mass and a dry-solids mass balance, and returns the resulting slurry mass flow — the figures that matter for slurry circuits.
Why must the target be lower than the initial solids?
Dilution adds water and lowers the percent solids. A target equal to or above the initial would be concentrating, not diluting, and the added-water figure would be zero or negative.
Does this guarantee the diluted slurry will pump or settle well?
No. It only gets the water and the resulting flow right. Pumpability, suspension, and settling depend on particle size and rheology from testwork, which this does not model.

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