Recovery of gold in iodine-iodide system – a review

Gold leaching in iodine-iodide solution has been intensely researched in 1980s; while due to the high cost, it has not been applied in industry. Currently, as the drawbacks of other hydrometallurgies appearing such as aqua regia and cyanidation, mining and exploration companies are shifting their attention to the iodide leaching, because which has low electrode potential, fast leaching kinetics, high leaching rate, mild reaction conditions and the lixiviant is easy to recover. The common gold leaching agents, although considerable researches have been undertaken, most, if not all, of which have been proven to have limitations that hinder their widespread adoption in the gold mining industry. Iodide leaching could serve as an effective mean for recovering gold through the dynamic, thermodynamic and electrochemical assessment. And a series of parameters, such as oxidants selection, the iodine/iodide ratio, solid-to-liquid ratio, acidity (pH) and leaching time, affect the gold leaching efficiency. Through a comparison with several other hydrometallurgical processes, the presenting merits promote iodine-iodide system to be a promising method for gold recovery. The key challenge of industrialization is how to reduce the cost and to recover gold from the lixiviant.