Application of hydrometallurgical technologies to valorise polymetallic industrial wastes

The present experimental study was carried out to apply hydrometallurgical technologies to valorise polymetallic industrial wastes. Precious metals content of the samples was very high (about 50 g/t Au). However, elemental and mineralogical composition hinders an economical treatment by standard process (cyanidation) finalised to precious metals recovery. In order to eliminate the refractoriness of the samples, pretreatments such as roasting and ultra fine grinding have been carried out before cyanidation. Moreover, an alternative leaching process of gold-bearing industrial wastes has been studied by using chlorine dissolved in brine solutions. Some results have been reported, to highlight limits and advantages of the proposed process.