SO₂ Cyanide Detox System

Benefits of the SO/O₂ system:
• 
• Can achieve low cyanide total in a single stage
• Low metals in solution
• Often lowest reagent cost
• Works well on both slurries and solutions
• Can remove iron cyanide

Process Manufacturing builds and delivers turnkey cyanide destruct systems using the SO₂/O₂ process. The process can treat slurries and solutions at high cyanide concentrations, resulting in low cyanide weak acid dissociable, CN_WAD and residual base metals in the tailings prior to tailings impoundment.

This process meets the target limits set by the Ministry of Environment and/or the ICMI Code compliance which can be as low as 1 mg/L CN total or less than 50 mg/L weak acid dissociable (WAD) cyanide for the discharge of final tails into a tailings storage facility. In Process Manufacturing’s cyanide detox system, pure oxygen or air is piped from the gas handling building to the cyanide destruction tank where the main chemical process occurs.

Also from the gas handling building, dry air is supplied to the SO₂ storage tank to keep the tank pressurized for the supply of SO₂ to the cyanide destruct tank via an automatic metering system.

A sodium metabisulfite reagent system can be provided which acts as a backup system in case of any issues with the SO₂ system or SO₂ supply. We can also provide copper sulphate and lime systems if required.

Online cyanide WAD analyzers can be provided so that SO₂ flow rates are added automatically based on the incoming cyanide levels. The final CN_WAD result informs the operators that the system is meeting target values at all times. The fully automated process requires little supervision by the mill operators.

Lime is added to the cyanide destruct tank to control the pH at target levels between a pH of 7 to 9. In the chemical process the metals are precipitated as hydroxides. The strong iron cyanide complexes are then precipitated with the addition of copper to form a cuproferrocyanide precipitate.

All systems and structures are assembled and tested at the Process Manufacturing facility in Surrey, BC and shipped complete to mine sites, saving on installation costs.