Tailings are the finely-ground rock residues left after the target metal has been extracted. Tailings management is the engineering discipline of safely storing or disposing of these residues — typically in a lined tailings storage facility (TSF), as paste backfill, or as dry-stacked filtered tailings. Modern tailings management is one of the highest-risk, highest-cost components of a mining project.
What Tailings Contain
Spent ore, residual processing reagents (cyanide if leach-derived, flotation reagents if mill-derived), water, and any environmentally-mobile metals not recovered. The chemistry varies enormously by deposit and processing flowsheet.
Conventional Wet Tailings Storage
Most large mines pump tailings as a slurry into an engineered, lined impoundment behind a dam. The dam is built progressively as the mine produces. Risks: dam failure (Brumadinho, Mariana, Mount Polley) — increasingly tightly regulated post-2019.
Filtered (Dry-Stacked) Tailings
An increasingly preferred approach: tailings are filtered to ~15–20% moisture and dry-stacked. No dam, far smaller water footprint, but more energy-intensive to filter. The Dolores project (Pan American Silver, KCA EPCM) uses pulp-agglomeration upstream of heap leach to consolidate fines.
Paste Backfill
Tailings can also be combined with cement and pumped underground as paste backfill — useful for underground mines where the backfill stabilizes worked-out stopes and reduces surface tailings storage.
KCA Capability
KCA designs tailings circuits as part of the overall plant — dewatering, thickening, filtration, and stack/dam design. The TSF design itself is typically partnered with a specialized geotechnical firm.
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