FUNGAL LEACHING OF NICKELIFEROUS LATERITES

Extraction of nickel by microbial leaching of Greek laterites is feasi ble by using of Aspergillus and Penicillium. The effectiveness was fou nd to depend on the ability of the microorganism to produce hydroxycar boxylic acids, especially citric acid, as well as other metabolites. T he nickel recoveries achieved were as high as 60 %, in 48 d, when the ore was leached in the presence of the living fungi, in a sucrose medi um, and as high as 70 %, in a much shorter time, when the ore was leac hed by their metabolic products after pH adjustment by means of sulfur ic acid. The use of much cheaper, factory grade, Greek beet molasses a s a growth medium proved promising, giving the possibility of making t he process more attractive in economic terms.