Getting more out of your copper SX plant.

A solvent extraction and crystallisation method is described for the recovery of Mo from Cu solvent extraction liquors. A modified phosphinic acid reagent formulation was developed to selectively remove Mo while leaving the majority of the impurity elements behind in the leach liquor. The extremely strong complex formed between the formulation and Mo results in a Mo loading which is nearly stoichiometric even at pH 0.1. Fe and Al may also be extracted from solutions at typical Cu raffinate pH values of 1.2-1.6, but their loading is significantly reduced at higher acidities or lower pH values and Mo may be separated from these common impurities by increasing the raffinate acidity prior to the Mo recovery stage. Mo is typically present in the leach liquors at very low concentrations of 5-100 ppm, and it is advantageous to extract the Mo using a very low flow organic/aqueous ratio. Organic recycle may be utilised to maintain proper mixing characteristics. Acidification of the raffinate stream prior to Mo extraction can greatly reduce the co-extraction of impurities and, depending on the final Mo product purity required, a scrub stage may also be necessary. Mo is stripped from the organic phase using a solution containing ammonia and ammonium carbonate and a high flow organic/aqueous ratio is advantageous for producing a concentrated strip liquor. Aqueous recycle may be used to achieve the necessary mixing conditions. The strip liquor is treated with sulphuric acid to generate a high-quality mixture of ammonium molybdate hydrates and molybdenum oxide hydrate crystals. The major impurities in the crystals were P and S, while minor impurities were As, Cu, Fe, Si, Zn, and Na. The crystal quality and purity could be improved with suitable washing of the filter cake. The results are presented of a pilot study carried out using one extraction and one stripping stage for a feed solution containing 75 ppm Mo and 40 g/l H2SO4. The aqueous feed and organic flow rates were 100 and
A solvent extraction and crystallisation method is described for the recovery of Mo from Cu solvent extraction liquors. A modified phosphinic acid reagent formulation was developed to selectively remove Mo while leaving the majority of the impurity elements behind in the leach liquor. The extremely strong complex formed between the formulation and Mo results in a Mo loading which is nearly stoichiometric even at pH 0.1. Fe and Al may also be extracted from solutions at typical Cu raffinate pH values of 1.2-1.6, but their loading is significantly reduced at higher acidities or lower pH values and Mo may be separated from these common impurities by increasing the raffinate acidity prior to the Mo recovery stage. Mo is typically present in the leach liquors at very low concentrations of 5-100 ppm, and it is advantageous to extract the Mo using a very low flow organic/aqueous ratio. Organic recycle may be utilised to maintain proper mixing characteristics. Acidification of the raffinate stream prior to Mo extraction can greatly reduce the co-extraction of impurities and, depending on the final Mo product purity required, a scrub stage may also be necessary. Mo is stripped from the organic phase using a solution containing ammonia and ammonium carbonate and a high flow organic/aqueous ratio is advantageous for producing a concentrated strip liquor. Aqueous recycle may be used to achieve the necessary mixing conditions. The strip liquor is treated with sulphuric acid to generate a high-quality mixture of ammonium molybdate hydrates and molybdenum oxide hydrate crystals. The major impurities in the crystals were P and S, while minor impurities were As, Cu, Fe, Si, Zn, and Na. The crystal quality and purity could be improved with suitable washing of the filter cake. The results are presented of a pilot study carried out using one extraction and one stripping stage for a feed solution containing 75 ppm Mo and 40 g/l H2SO4. The aqueous feed and organic flow rates were 100 and