n型とp型黄鉄鉱の溶解メカニズムの相違

抄録

In order to investigate the difference of the reaction paths between n-and p-tyep pyrite crystals during oxidation at room temperature in aqueous solutions, the shape and size of pyrite cyrstals during dissolution have been measured in various conditions. Two types of experiments were performed by changing the size of pyrite cyrstals. The one was to measure the value of Eh (oxidation-reduction potential) and pH using pyrite crystals ranged from 106 to 125μm. The size was <20μm and thus DLS (Dynamic light scattering) was employed during the dissolution in the other experiment. The oxidation of n-type pyrite proceeds via the oxidation of sulfur, whereas p-type pyrite proceeds via the oxidation of Fe^<2+> to Fe^<3+>. The dofference is attributed to the easiness of sulfur dissolution from the n-type pyrite than from the p-type pyrite due to the sulfur rich compositon. The same applies to easiness of iron dissolution from the p-type pyrite than from the n-type pyrite due to the iron rich composition. Phase-contrast microscopy was also employed to observe the change of the shape of pyrites, which showed a needle shape in the beginning of the dissolution process.