Pressure oxidative treatment of whole ores and/or mineral concentrates is used to leach or liberate metals of value for downstream recovery. Silver, when present, is often lost in processing, precipitating as a cyanide-insoluble jarosite in the residue. Depending on pressure oxidation conditions, the degree of silver loss to jarosite can vary dramatically. Batch testwork is often performed to define that loss, and then assess the implications at a continuous scale.
When a silver-insoluble anion, iodide, is dosed prior to oxidation, there is a marked improvement in silver recovery from batch-generated residue; however, that benefit is not consistently seen in continuous testwork. This paper focusses specifically on CESL pressure oxidation conditions with respect to the impact on silver recovery, and discusses limitations of the batch testing process as well as means of overcoming these limitations to better predict silver recovery in the scale up from bench to continuous system operation.