Ferric Sulphate Percolation Leaching of a Pyritic Zn-Pb-Cu Ore

A pyritic Zn-Pb-Cu ore waspercolation leached with acidified ferric sulphate solutions; zinc and copper were leached, lead was oxidized, but not dissolved, and pyrtte was essentially unattacked. High zinc extractions were achieved after a few months leaching, and substantial zinc solution concentrations could be produced by recycle of the oxidized solution. The leaching rate was generally controlled by the transport of the ferric sulphate oxidant. Zinc extractions increased with increasingferric ion concentration or flow rate, but were essentially independent of the concentrations of sulphuric acid, ferrous sulphate, cupric sulphate or chloride ion. The leaching rates were insensitive to the height of the ore column once a minimum height had been exceeded (0.8-1.0 m). Elemental sulphur was the principal sulphidic reaction product, but variations in the ratio of sulphur to sulphate produced anomalous temperature effects.