NATIONAL TECHNICAL UNIVERSITY OF ATHENS
SCHOOL OF MINING AND METALLURGICAL ENGINEERING
Section of Metallurgy and Materials Technology
Laboratory of Metallurgy
 
HYDROMETALLURGY UNIT

 
b. Bioleaching
 
The Biological Treatment Processes Laboratory is dedicated to the examination of the chemical and biological fate and treatment of metals found in aquatic and subsurface environments and in engineered treatment and manufacturing systems. The purposes are to utilize biotechnology for metal recovery, as well as remediation of soil and groundwater.
 
Bioleaching is a process, whereby metals are leached from ore as a result of  bacterial action. In nature, bioleaching is triggered spontaneously by micro-organisms in the presence of air and water. Commercially applied bioleaching technologies utilize the same phenomenon, but accelerate the process significantly by increasing the amount of bacteria and by improving their living conditions through added air, water and nutrients
 
The bioleaching bacteria get their energy by oxidizing iron and inorganic sulphur compounds, and they derive carbon for their growth from carbon dioxide in the air. The bacteria also need small amounts of trace nutrients such as phosphorus, magnesium and ammonia nitrogen. As a result of bioleaching, the sulphides in the ore are oxidized to sulphates and the metals are liberated into solution as metal ions.