The Albion Process™ technology can be incorporated with conventional metal recovery technologies, such as cyanide leaching for the recovery of precious metals, and either direct electrowinning or solvent extraction and electrowinning for the recovery of base metals.
The oxidative leach can be operated under a range of pH conditions, varying from acidic to neutral. For the processing of a refractory gold/silver concentrate, the pH of the oxidative leach is held at 5.5 by the continual addition of limestone slurry to ensure complete oxidation of the sulphur to sulphate. The oxidised residue can then be fed directly to a cyanide leach plant for precious metals recovery.
The oxidative leach is operated under acidic conditions for copper, zinc, cobalt and nickel concentrate leaching. The acidic oxidative leach is a two stage process, where economic metals are first leached in oxygenated acidic solution, with the acidic leach slurry then neutralised to precipitate iron and other deleterious elements such as arsenic, prior to separation of the leached solids and recovery of the economic metals from the neutralised leach solution. A goethite precipitation circuit is well suited for neutralisation of the oxidised slurry.
The neutralised slurry will be filtered and the filtrate advanced for recovery of the copper, zinc, cobalt or nickel. Metal recovery can be via conventional processes such as direct electrowinning, solvent extraction/electrowinning or mixed product precipitation.