Gate Valves for Mining & Minerals

For tailings slurry (high-concentration coarse or fine tailings, PN 10–16), rubber-lined gate valves are the standard choice. The rubber lining (natural rubber 60–65 Shore A for abrasive service, or polyurethane for fine tailings) protects the carbon steel body from abrasion and provides a resilient seat seal. For very high solids content (>50% w/w) or coarse slurry with particle size >10mm, consider knife gate valves or pinch valves instead. Gate valves in tailings service should always be 'open or closed' — never used for throttling — as the partly-open gate creates a high-velocity erosion zone at the seat and disc edge.

Yes. SS 316L (1.4404) is the standard material for sodium cyanide (NaCN) heap leach and CIL/CIP circuits in gold mining. Dilute NaCN (0.1–1 g/L NaCN, pH 9.5–11 for stability) is not particularly corrosive to SS 316L. The concerns in cyanide service are: (1) packing emissions — use PTFE chevron packing to prevent cyanide vapour exposure at the stem; (2) weld quality — ensure full-penetration welds to avoid crevice corrosion; (3) avoid copper alloy components (bronze, brass) — cyanide complexes with copper. For concentrated NaCN storage (>10 g/L) or acidic process conditions (pH <8), consult with a corrosion engineer.

Sizing steps: (1) Determine maximum pump discharge flow rate (m³/hr) and pipeline velocity — target 1.5–2.5 m/s for clean water, 1.8–3.0 m/s for mine water with fines; (2) Select nominal bore from published Cv/Kv tables to match pipeline bore (gate valves are typically full-bore — use the same nominal bore as the pipe); (3) Calculate pressure drop across the fully-open gate valve — should be <0.5 bar at maximum flow; (4) Select pressure class from maximum pump shut-off pressure (closed valve full pump pressure); (5) Factor corrosion allowance — mine water often contains dissolved iron, chlorides, and acids that attack carbon steel; specify SS 316L or lined valves accordingly.