The Study On Interaction Between Acidianus Manzaensis YN25 And Chalcopyrite And Its Leaching Characteristics

The purpose of the paper was to know the change of the surface properties of Acidianus manzaensis YN25 after the interaction with chalcopyrite, the adsorption mechanism of A.manzaensis YN25 on chalcopyrite and its leaching characteristics. In the present study, the surface properties of A.manzaensis YN25 grown on different energy resources were studied in terms of Zeta-potential and contact angle. Real-time quantitative PCR was used to calculate the adsorption of A.manzaensis YN25 on chalcopyrite. The adsorption mechanism of microorganisms on chalcopyrite could be illustrated by the surface thermodynamics and extended DLVO theory. The contribution of contact and non-contact cells of A.manzaensis YN25 to the bioleaching of chalcopyrite was studied. The mechanism of microorganism-chalcopyrite interactions was explored. And a mixed culture of extremely thermophilic archaea was used to bioleach chalcopyrite. Results obtained as follows:The results of research on surface properties and adsorption suggested that A.manzaensis YN25 cultured on different energy resources had the similar surface structure, and so was the change trend of surface properties of chalcopyrite after conditioning with different types of A.manzaensis YN25. The potential energy curve deduced by extended DLVO theory showed that at pH 2.5, acid-base interaction between A.manzaensis YN25-chalcopyrite was strong repulsive, while electrostatic force was very weak and Lifshitz-van der Waals force was very strong attractive force. Therefore the total interaction force of A.manzaensis YN25-chalcopyrite was attractive all the time, so adsorption of A.manzaensis YN25 was possible on chalcopyrite. At pH 10.5, electrostatic force was strong repulsive, while acid-base interaction and Lifshitz-van der Waals forces were similar as pH 2.5. Therefore the total interaction force of A.manzaensis YN25-chalcopyrite was repulsive all the time, caused that there would be no adsorption of A.manzaensis YN25 on chalcopyrite. All types of A.manzaensis YN25 adhered to chalcopyrite surface rapidly, the adsorption equilibrium was attained in about 60 mins, and the chalcopyrite adapted A.manzaensis YN25 had the strongest adsorption ability. The adsorption rose with the increase of initial cell concentration, but the growth rate of adsorption gradually slowed down. The adsorptive capacity of A.manzaensis YN25 is the best when pH value is in range of 1.5-3.5 and the temperature is 65℃, however, the influence of temperature is not significant.It was found that the leaching of chalcopyrite was the cooperative action of the contact and non-contact A.manzaensis YN25. The analysis of leached residues in this experiment indicates that the passivation of chalcopyrite concentrate was mainly due to the elemental sulphur layer on the mineral surface. The surface passivating layer of sulfur could be removed only when A.manzaensis YN25 could contact the surface of the chalcopyrite. The amount of protein on the surface of A.manzaensis YN25 was higher when the cells could contact chalcopyrite, which endowed the cells with more hydrophobicity.A mixed culture of extremely thermophilic archaea was used to bioleach chalcopyrite. The results showed that the mixed culture had a high chalcopyrite-oxidizing ability:about 88% copper extraction was achieved. And Sulfolobus metallicus was dominant in microbial community at the early stage of leaching, its proportion reached 60%, whereas A.manzaensis YN25 thrived at the latter stage.