Ball Valves for Mining & Minerals

SS 316L is the standard body material for dilute sodium cyanide (NaCN) solutions (0.1–2 g/L, pH 9–11) used in heap leach and CIL/CIP gold processing. The high pH (above 9.5) is maintained to prevent HCN gas evolution, and at this pH SS 316L has good corrosion resistance. Specify PTFE seats (superior chemical resistance versus RTFE for HCN-adjacent environments), graphite or PTFE packing on the stem (prevent cyanide vapour release), and avoid all copper alloy components. For higher concentration NaCN storage (>50 g/L) or where pH control is unreliable (acid leach environments), Super Duplex 2507 or Hastelloy C-276 provide additional safety margin.

Standard floating ball valves with PTFE seats are not suitable for continuous abrasive slurry service — the abrasive particles in the flow path erode the PTFE seat surface, causing leakage within weeks of installation. For abrasive slurry: (1) Use knife gate valves or pinch valves as the primary slurry isolation device; (2) If ball valves are required for slurry service, specify metal-seated ball valves with tungsten carbide, chrome carbide, or hardened SS seat surface coatings; (3) Minimise the number of open/close cycles in slurry service — every cycle wears the seat; (4) Install ball valves on clear-water flush lines and bypass flushed connections where possible, rather than directly in the slurry pipeline.

Underground mine compressed air ball valve specification: Body: A216 WCB or ductile iron for DN25–300; SS 316L in areas with acid mine drainage exposure. Pressure class: Class 150 (PN 20) standard; Class 300 (PN 50) for higher-pressure drill rig circuits (8–12 bar). Fire-safe: API 6FA or ISO 10497 certified — mandatory in underground hydrocarbon environments. Anti-static: Required per API 608 Annex D to prevent electrostatic discharge in explosive atmospheres. Lockout: Specify stem-lockable design or padlockable lever handle — essential for LOTO (Lock-Out/Tag-Out) compliance. Size to pipeline bore: Full-bore ball valve to maintain air tool supply pressure.