Study On Mechanism And Dissolution Characteristics Of Gangue Minerals In Bioleaching Of Chalcopyrite

The characteristics of the typical and most abundant gangue minerals associated with chalcopyrite including quartz; sericite, fluorite, hydroxyapatites and dolomite was studied. The leaching rule, effects on chalcopyrite bioleaching and the mechanism of gangue minerals, consisting of single and multiple gangue mineral and that associated with chalcopyrite, in chalcopyrite bioleaching system was investigated, and the leaching rules were determined.In the single mineral system with a similar environment to chalcopyrite bioleaching system, the gangue minerals were dissolved by acids, At.f bacteria and its metabolic product. Its rate was also subject to particle size and whether the environment facilitates growth and fertilization of Acidithiobacillus ferrooxidans: The following order of these gangue minerals dissolving rate prevailed:dolomite> fluorite> hydroxyapatites> sericite> quartz The dissolution of quartz and sericite was fitted to the internal diffusion model of the shrinking core model, whilst hydroxyapatites’behavior can be interpreted by pore diffusion model of porous particle model. The order of their impact on copper leaching was:sericite> hydroxyapatites> quartz> blank> fluorite> dolomite. However, their dissolution performed differently in the multi-mineral system to a single or dual one. Si and Al3+ dissolution from quartz or sericite were depressed, whilst their overall dissolution was facilitated by F" from fluorite. Dolomite was completely dissolved in 4 days, and its dissolved species hindered the dissolution rate of hydroxyapatites and fluorite. In gangue mineral and chalcopyrite associating system, the concentration of ions with a high density that dissolved from disseminated mineral promoted At.f bacteria’s growing, but the ore structure determined that it was easier for chalcopyrite to be leached from crumb chalcopyrite than that of disseminated.Mineral dissolution behavior was subject to its own physicochemical properties (e.g. crystal structure, lattice energy and solubility) and performs similarly in a single mineral system with a chalcopyrite bioleaching environment. Further, variation of surface adsorption of gangue minerals to At.f bacteria, the investigation by FTIR spectroscopy and Zeta potential revealed their dissolution mechanism. Moreover, XRD analysis on leaching residue discovered that no new chemicals formed during fluorite bioleaching, but calcium phosphate and calcium sulfate were observed in dolomite system, whilst a type of ammo niojaro site for the others. SEM and EDS studied unearthed that these new materials absorbed on mineral surface, hindering further dissolution. The absorption degree of the material on surface was consistent to their dissolution rate, and further inversed to copper leaching rate, implying that chemical forming on gangue mineral surface promotes chalcopyrite leaching although its mechanism was unclear. The findings in the study provided new fundamentals for manipulating chalcopyrite bioleaching process via controlling gangue minerals dissolution。...