ELECTROCHEMICAL RESEARCH OF PROCESS OF BIOLEACHING OF GERMANIUM FROM COALCONCENTRATING DUMPS

Study of extraction of germanium from dump of technogenic origin by electrochemical method at constant of potential was the purpose of the research. The research of process of bioleaching of germanium from firm anthropogenic substrate with native bacteria was carried in a potentiostatic mode. Objects of the research were the dumps of technogenic origin with long (red) and short (black) term of natural storage in which the presence of native bacteria is possible. The source of energy for activating the leaching activity of various groups of bacteria that inhabit the aboriginal consortium of industrial wastes can be ferrous ions in the form of FeSO4. The electrochemical studies were carried out on the potentiostat ПИ 50.1. in a two-chamber three-electrode cell with two types of membranes (polyethylene and porous polypropylene). The bioleaching in potentiostatic mode at potential of 0,65 V in mineral solution at a temperature 30°С during 3 days was carried. It is determined, that maximal leaching is observed at a constant potential of system 0,65 V and concentration of ion Fe2+ in nutritious environment 8,96 g/l. The speed of bioleaching of germanium for polythene membrane does not depend from the type of dump and amount (8,5±0,3)·10-2 mg/l·h. The mechanism of bioleaching of germanium differs for red and black types of dump. Concentration of germanium for the second day passes through a maximum for red and minimum for black dump. When using the polypropylene membrane the speed of bioleaching of germanium is higher (9,7·10-2 mg/l·h). During the discharge it is maintained practically constant concentration of ions Fe2+ necessary for two opposite processes Fe2+↔ Fe3+. Quantity of germanium in a solution for I-III day is approximately identical. The obtained data indicates that, at the potential of 0,65 V, the destruction of the crystal structure of the dumps, apparently, occurs at the moment of transition Fe2+↔ Fe3+. It promotes the bioleaching of ions of germanium.