Tailings Dam Volume Estimator
The mass method converts a deposited mass of dry solids into the volume it occupies once settled: storage volume (m³) = dry tailings mass (t) ÷ settled dry density (t/m³).
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- For the mass method, enter the dry tailings mass (tonnes of solids, not slurry) and the settled dry density (from testwork, typically ~1.1–1.6 t/m³).
- For the geometric method, enter the pond footprint area (m²) and the average settled depth (m) to get the physical stored volume.
- Fill both sets to cross-check the deposited-solids requirement against the available physical void; read results in m³ or ML (1 ML = 1,000 m³).
How it works
The mass method converts a deposited mass of dry solids into the volume it occupies once settled: storage volume (m³) = dry tailings mass (t) ÷ settled dry density (t/m³). Settled dry density is the mass of dry solids per cubic metre of settled tailings and comes from consolidation testwork — it is not the slurry density or the specific gravity of the mineral.
The geometric method treats the storage as a physical prism: pond volume (m³) = footprint area (m²) × average settled depth (m). Both results are also shown in megalitres (ML = m³ ÷ 1,000). This is a first-pass storage estimate: it ignores beach slopes, freeboard, decant pond, seepage, ongoing consolidation and staged embankment raises, all of which a designed tailings storage facility must account for.
Worked example
Storage for 500,000 t of dry tailings at 1.4 t/m³. A processing plant deposits 500,000 t of dry tailings solids into a TSF that settles to a dry density of 1.4 t/m³. Storage volume = 500,000 ÷ 1.4 = 357,142.86 m³, which is 357.143 ML. That is the settled void the tailings will occupy — freeboard, beach slopes and decant pond are additional.
Common mistakes
- Using slurry (wet) tonnes or slurry density instead of DRY solids mass and SETTLED DRY density — this overstates the volume badly because slurry is mostly water.
- Confusing settled dry density (t/m³ of settled tailings) with the mineral's specific gravity (2.6–4+); dry density is far lower because of void space and always makes the volume larger.
- Treating the estimated volume as usable capacity — actual capacity must deduct freeboard, beach above the decant, and account for consolidation gains over the deposition life.
Frequently asked questions
What settled dry density should I use?
Use a value from site-specific consolidation/settling testwork. Typical ranges are roughly 1.1–1.6 t/m³ for fine tailings and higher for coarse or thickened/paste tailings, but it rises over time as tailings consolidate. Do not guess for design — this tool is for scoping estimates only.
Why do the mass and geometric methods give different answers?
They answer different questions. The mass method tells you the volume the deposited solids need at your assumed settled density; the geometric method tells you the physical void a given footprint and depth provide. Reconciling them (with freeboard, beaching and consolidation) is part of tailings design.
Does this size the embankment or check dam safety?
No. This only estimates stored volume. Embankment geometry, stability, freeboard, seepage, decant capacity and closure are engineering-designed by a competent tailings professional to the applicable dam-safety guidelines.
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