Biophysical Studies on Carbonaceous Shales, Magharet El Meyiah Formation, Southwestern Sinai, Egypt

Abstract

Compared to conventional chemical leaching methods, a biohydrometallurgical approach is generally considered to be a ‘‘green technology’’ for the extraction of metals from solid materials. In this respect, it is an approach that offers many attractive features such as environmental benignity, operational flexibility and low energy requirements and cost. It was shown that bioleaching realised higher metal extraction than chemical leaching.The main concern of the present work is to study the characteristic features of different carbonaceous shale samples with its biomass contents and the effect of both on the bioleaching and biosorption of rare earth elements ( REEs ) and other associated metals. The extraction of low concentrations of metal ions from this ore material indicated that this low grade ore may be a potential source for metal ions in the future.The present study is stressed on samples from Magharet El Meyiah Formation of early Carboniferous age in southwestern Sinai, Egypt. A total of sixteen representative samples were collected to represent the lithologic variations from north Budaa (B) , middle El Gor (G ) and south G. Farsh El Azraq localities. Carbonaceous shales show REEs content ranging between 200 ppm with an average of 366 ppm.Eight fungal genera were isolated from the studied samples. The most dominant were Aspergillus and Penicillium. The Aspergillus ( A. ) was identified as A. niger, A. flavus, A. terreus and A. ficuum whereas, Penicillium ( P. ) was P. aeruginosa, P. oxalicum, P. cyclopiumand P. diversum. All of the tested fungi could grow in the presence of 1% ore concentration of the studied Budaa locality samples B.3, B.4 and B. It was found that direct bioleaching process of REEs from the tested samples was more effective than indirect process for all tested microorganisms. The bioleaching percentages of REEs from the tested samples by Aspergillus sp. were more than Penicilium sp. whereas; A. niger was the superior followed by A. flavus.Optimum conditions of REEs bioleaching by A. niger and A. flavus on Budaa sample B.3, were found at 1% ore concentration, 7 days incubation period, 30 °C incubation temperature and pH 4 and reached 86% and 73% bioleaching efficiency, respectively. The best bioleaching efficiency 91% of REEs is found in El Gor locality sample G.1 which has the lowest content of REEs concentrations.