Fractal analysis to discriminate between biotic and abiotic attacks on chalcopyrite and pyrolusite

In the present paper, a model describing release and mobility of copper and manganese in chalcopyrite and pyrolusite powders due to bacterial bioleaching, i.e. Thiobacillus ferrooxidans and Arthrobacter sp., is proposed. Sites where copper and manganese were released were examined by scanning electron microscopy (SEM). The resulting micrographs were scanned and submitted to a point by point fractal analysis to verify if a discrimination between biological and chemical attack could be established on the basis of the distribution of the fractional part of the fractal dimension over the whole surface. We demonstrate that such a method is able to discriminate among the different attacks.