Sodium Cyanide Storage & Tank Compatibility

Storing Sodium Cyanide? Start Here

Sodium cyanide (NaCN) is a white, deliquescent salt that dissolves readily in water to give a clear, strongly alkaline solution. It is one of the most important industrial cyanide reagents: the backbone of gold and silver leaching in mining, a feedstock for electroplating baths, and a building block in the manufacture of nitriles, chelants, and fine chemicals. In solution the cyanide ion is chemically well tolerated by polyethylene, which is why HDPE-lined ponds, poly tanks, and poly piping are the everyday containers for cyanide leach liquors. The dominant design concern is therefore safety rather than resin attack. The solution is acutely toxic by every route, and any drift toward neutral or acidic pH — or accidental contact with an acid — liberates hydrogen cyanide gas, which can be rapidly fatal. Tank selection, alkalinity control, venting, segregation from acids, and spill capture together define safe storage of this material.

Is Polyethylene (HDPE / XLPE) Compatible with Sodium Cyanide Solution?

Verdict: Compatible (S) for ambient aqueous solutions. Sodium cyanide is an inorganic salt, and its strongly alkaline water solution falls squarely in the family of salts and aqueous solutions that polyethylene handles well. HDPE and XLPE are, in fact, the industry-standard materials for cyanide service: gold and copper heap-leach operations move and store millions of gallons of cyanide leach solution in HDPE-lined ponds, poly tanks, and poly pipe. There is no meaningful chemical attack on the resin from the cyanide ion at ambient temperature. The caveats are operational, not material: keep the solution cool (commodity poly loses strength when hot), keep it strongly alkaline so dissolved HCN stays in the ionic form, use vented and properly gasketed fittings, and provide secondary containment. For any hot, acidic, or oxidizer-loaded cyanide process bath, step up to PVDF or a lined specialty vessel and confirm against a polyethylene resistance chart and the product SDS.

Material compatibility at a glance

Store aqueous sodium cyanide solutions in HDPE/XLPE, PP, PVC/CPVC, or PVDF tanks kept cool and strongly alkaline (high pH suppresses HCN release). Polyethylene is the standard, field-proven container for cyanide brines in mining. The critical control is not resin chemistry but segregation: never store or plumb cyanide anywhere it can contact acid, because that liberates hydrogen cyanide gas. Provide secondary containment, vented closures, and capture all spills and rinse water for cyanide-destruction treatment before discharge.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Acutely toxic by all routes — fatal if swallowed, in contact with skin, or inhaled; treat as a super-toxic material and keep a cyanide antidote kit and trained responders on site.
• Hydrogen cyanide gas is released on contact with acid or as solution pH falls — never store or plumb cyanide near acids, pickles, or acid drains, and maintain high alkalinity.
• Very toxic to aquatic life with long-lasting effects — capture and treat all spills and rinse water by cyanide destruction before any discharge.
• Serious eye damage and skin irritation — the alkaline solution attacks tissue; full chemical-resistant gloves, apron, and face shield are required.
• Organ damage on prolonged exposure and suspected reproductive hazard — minimize exposure with local exhaust ventilation and closed transfer.
• Secondary containment and venting — bund cyanide tanks separately from acids, vent closures, and label clearly for emergency response.

Common questions

Can I store sodium cyanide solution in a poly (HDPE/XLPE) tank?

Yes. Aqueous sodium cyanide is an alkaline salt solution that polyethylene tolerates well, and HDPE/XLPE is the industry-standard container for cyanide leach liquors in mining. Keep the solution cool and strongly alkaline, use vented gasketed fittings, and provide secondary containment. The limiting factor is safety and segregation from acid, not chemical attack on the resin.

Why is keeping the solution alkaline so important?

Cyanide in solution exists in equilibrium with hydrogen cyanide. High pH keeps it as the relatively safe cyanide ion; as pH falls toward neutral or acidic, dissolved HCN is released as a toxic gas. Maintaining strong alkalinity in storage is a core safety control, not just a chemistry preference.

What is the single most dangerous mistake?

Letting cyanide contact acid. Cyanide salts or solutions plus acid liberate hydrogen cyanide gas, which can be rapidly fatal. Cyanide and acid systems must be physically segregated with separate bunding, drains, and clear labeling.

Does sodium cyanide attack the polyethylene tank itself?

No meaningful chemical attack occurs at ambient temperature. The cyanide ion is chemically tolerated by polyethylene, which is why poly is used throughout cyanide handling. Resin limits only become relevant for hot or acidified process baths, where a heat-rated lined or PVDF vessel is the better choice.