Pumps & Rotating Equipment

Slurry Pump Head Sizing

Preliminary pump head considerations for slurry service in mining and mineral processing: slurry SG and solids loading, why clean-water friction estimates are only a starting point, deposition velocity, wear, settling, and why experienced slurry-pump review is required.

TypeEngineering guide — concept explainer

Definition

Slurry pump head sizing is the preliminary assessment of the head a pump must develop when the fluid is a mixture of liquid and suspended solids — typical of mining and mineral processing duties such as tailings, concentrate, and mill discharge. The starting point is the same hydraulics used for clean liquids, but slurry density (SG), solids loading, particle size, and abrasiveness all change the result, and the friction behaviour of settling slurries is not reliably captured by clean-water correlations. Because of this, slurry pump head sizing is genuinely preliminary and must be confirmed by a vendor or an experienced slurry-pump engineer.

Why it matters

In a slurry system the head and the power both scale with the slurry specific gravity, so a duty that looks modest on water can demand a much larger drive once solids are included. At the same time the pipe velocity must stay above the deposition (settling) velocity or solids drop out, block the line, and spike the head — yet too much velocity accelerates wear of the pump and pipe. Getting head sizing wrong therefore shows up as blockages, premature wear, or an under-powered drive, all of which are expensive in a mineral-processing plant. This is why slurry duties are sized conservatively and reviewed by specialists rather than taken straight from a clean-water calculation.

Formula

Slurry specific gravity

SG_slurry = 1 / ( Cw/SG_solids + (1 − Cw) )

Pressure from slurry head

ΔP_slurry = ρ_slurry × g × h

Head scaling (approx.)

ΔP_slurry ≈ SG_slurry × ΔP_water-equivalent

Velocity check

v_operating > v_deposition (settling velocity)

Units involved

•Cw, Cv — solids concentration by weight / volume (fraction or %)
•SG — specific gravity of solids and of the slurry (dimensionless)
•ρ — density in kg/m³ or lb/ft³
•h — head in metres (m) or feet (ft)
•v — velocity in m/s or ft/s
•Q — flow in m³/h, L/s, or gpm

Concept diagram

Worked example

A tailings slurry runs at 30% solids by weight (Cw = 0.30) with solids SG = 2.65. Estimate the slurry SG and the head impact relative to an equivalent clean-water duty. (Friction and deposition velocity must still be checked separately.)

01SG_slurry = 1 / ( 0.30/2.65 + 0.70 )
02SG_slurry = 1 / ( 0.1132 + 0.70 ) = 1 / 0.8132
03SG_slurry ≈ 1.23
04ΔP at a given head ≈ 1.23 × the clean-water value
05Confirm operating velocity exceeds the deposition velocity for the particle size

Result

Slurry SG ≈ 1.23, so pressure and power rise ~23% versus water at the same head. Treat as preliminary — confirm friction, velocity, wear, and NPSH with a slurry-pump specialist.

Common mistakes

•Applying clean-water friction correlations directly to settling slurries without caution.
•Forgetting to scale head, pressure, and power by the slurry SG.
•Operating below the deposition velocity, causing settling and blockages.
•Chasing very high velocity to avoid settling, which accelerates wear.
•Ignoring NPSH — slurry suction conditions and viscosity reduce available margin.
•Skipping vendor / specialist review for an abrasive, high-solids duty.

When to use the calculator

Use the Slurry Solids calculator to get Cw/Cv and slurry SG, the Head ↔ Pressure calculator to convert head with the slurry density, the Pipe Head Loss calculator for a clean-water friction starting point (with caution), and the Pump Power calculator with the slurry density to estimate drive power.

Head ↔ Pressure Calculator →Pipe Head Loss Calculator →Slurry Solids Calculator →Slurry Density Calculator →Percent Solids Mass ↔ Volume Calculator →Pump Hydraulic Power Calculator →

FAQ

Can I just use a clean-water pump head calculation for slurry?

Only as a starting point. Slurry SG scales head, pressure, and power, and the friction behaviour of settling slurries departs from clean-water correlations. Use clean-water numbers cautiously and confirm with a slurry-pump specialist.

How does slurry SG change the head requirement?

Head in metres of slurry is the same geometric height, but the pressure and the power both scale roughly with the slurry SG. A slurry at SG 1.3 needs about 30% more pressure and power than water at the same head and flow.

What is deposition velocity and why does it matter?

It is the minimum velocity that keeps solids in suspension. Below it, solids settle and can block the line, sharply raising head. Above it, wear accelerates. Slurry lines are sized to sit in a safe band above the deposition velocity for the actual particle size.

Why is vendor review essential for slurry pumps?

Abrasive, high-solids duties affect impeller and liner material, derated curves, wear life, and gland/seal arrangement — none of which a preliminary head calculation captures. Experienced slurry-pump vendors size these from operating data and test work.