Hydrogen peroxide and Caro’s acid for cyanide destruction

The reaction between cyanide and hydrogen peroxide or Caro’s acid produces cyanate (CNO-) and water or cyanate and sulfate according to whichever reagent is used.
Cyanate (CNO-) is regarded as being at least 1,000 times less toxic than cyanide.  The cyanate will hydrolyse over time depending on the pH to give carbon dioxide and an ammonium salt or carbonate and ammonia.

The reaction between cyanide and hydrogen peroxide takes time but can be  catalysed by the presence of copper.  Copper is often present in effluents originating from the treatment of ores but in some cases, it may be necessary to add small amounts  of  copper sulfate to accelerate the reaction.

The reaction between cyanide and Caro’s acid is extremely fast and does not need to be catalysed.

The choice between reagents

In the case of leaching ores where compounds such as thiocyanates, ferric ions, etc.are present,  the use of  Caro’s acid is recommended.
The reagent of choice depends on a large number of variables.  Our specialists are at your disposal to determine which is the best solution and operating conditions for your particular case.