BIOLEACHING OF SUKINDA LATERITE USING ULTRASONICS

Many metallurgical processes have been developed for the extraction of nickel from Sukinda lateritic nickel ore. These processes consume muc h energy and are also costly. Biological activities of microorganisms have been known to cause metal solubilisation from low grade ores in a cost effective way. The bioleaching efficiency of an organism is rela ted to its growth rate. In our previous study we found an increased gr owth of Aspergillus niger after ultrasound treatment of spores. The pr esent work was undertaken to examine the effect of ultrasound pretreat ment on nickel leaching using a native strain of A. niger: The maximum leaching of nickel (92%) was achieved after 20 days, along with 12.5% of iron in the control experiment (without ultrasound treatment). On the other hand, in the set treated ultrasonically, 95% of nickel could be leached selectively only after 14 days. This increased ability of the organism in nickel bioleaching may be due to the enhanced growth o f A. niger.