The International Cyanide Management Code (ICMC), commonly shortened to the Cyanide Code, is a voluntary, performance-driven programme for the safe management of cyanide used in the production of gold and silver. It is administered by the International Cyanide Management Institute (ICMI) and sets performance standards across the full cyanide life cycle: production, transport, storage, use on site, decommissioning, worker safety, emergency response, and community engagement. Mining companies, cyanide producers, and cyanide transporters become signatories voluntarily and must then have their operations independently audited and certified as being in compliance with the Code.
The Code is built around a set of principles and supporting standards of practice rather than a single numeric limit. Signatory operations commit to designing, operating, and decommissioning facilities in ways that protect workers, communities, and the environment from the hazards of cyanide. Certification is not a one-off exercise: certified operations are re-audited on a three-year cycle by independent third-party auditors who meet ICMI's requirements for experience, expertise, and freedom from conflicts of interest, and audit results are published on the Institute's website for transparency.
For the environment, the Code frames its cyanide exposure requirements in terms of WAD cyanide (Weak Acid Dissociable cyanide) rather than total cyanide. WAD cyanide captures the free cyanide and the labile metal-cyanide complexes that are the more toxicologically relevant fraction for wildlife, while excluding the stable iron-cyanide complexes, which are far less bioavailable. This is why WAD cyanide, rather than total cyanide, is the metric most commonly monitored against Code-related wildlife targets and site environmental licence conditions.
A frequently referenced benchmark is the protection of wildlife around tailings storage facilities, where open water accessible to birds and other animals is commonly managed to a WAD cyanide concentration at or below 50 mg/L. The Code itself does not impose that figure as a universal legal limit; it requires operations to implement measures that protect wildlife, and the 50 mg/L open-water benchmark is the widely adopted management practice used to demonstrate that protection. Site-specific environmental licences and national regulations may set tighter limits.
Meeting Code and licence requirements depends on reliable, defensible cyanide measurement. Operations monitor WAD and available cyanide in tailings solution, process streams, and discharge points using established analytical methods, most commonly the available-cyanide methods OIA-1677 and ASTM D6888, which use ligand exchange and gas diffusion followed by amperometric detection. Available cyanide is a close analytical proxy for WAD cyanide rather than an identical measure. Continuous flow analysers such as the FS3700 run these methods at laboratory throughput, giving the documented, traceable data that certification audits and regulators expect.
Key Points
- A voluntary certification programme for the safe use of cyanide in gold and silver mining
- Administered by the International Cyanide Management Institute (ICMI); participation is by signatory commitment
- Covers the full life cycle: production, transport, storage, use, decommissioning, safety, and emergency response
- Certified operations are independently audited on a three-year recertification cycle
- Environmental requirements are framed in WAD cyanide, not total cyanide
- A WAD cyanide concentration at or below 50 mg/L in wildlife-accessible open water is a widely used management benchmark
Relevant Standards
- International Cyanide Management Code (the Cyanide Code), administered by ICMI
- OIA-1677 / ASTM D6888 (available cyanide by ligand exchange, gas diffusion, amperometric detection; a close proxy for WAD cyanide)
- APHA 4500-CN⁻ I (weak acid dissociable cyanide by distillation, pH 4.5)
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Frequently Asked Questions
Is the ICMC a law or a regulation?
No. The International Cyanide Management Code is a voluntary, performance-driven certification programme, not legislation. Mining companies, cyanide producers, and transporters choose to become signatories and are then independently audited against the Code. It sits alongside, and does not replace, the national and state environmental laws and licence conditions that legally apply to an operation.
Does the ICMC set a WAD cyanide limit?
The Code does not impose a single universal numeric limit. It requires signatory operations to protect workers, communities, and wildlife, and to comply with applicable laws. In practice a WAD cyanide concentration at or below 50 mg/L in wildlife-accessible open water is the widely adopted management benchmark used to demonstrate wildlife protection, while site-specific environmental licences may set tighter limits.
Why does the ICMC use WAD cyanide instead of total cyanide?
Because WAD cyanide better reflects environmental risk. It includes free cyanide and the labile metal-cyanide complexes that are toxic and bioavailable to wildlife, while excluding the stable iron-cyanide complexes that are far less hazardous. Managing to a WAD figure therefore targets the species that actually pose ecological risk, which is why Code-related monitoring is reported in WAD cyanide terms.