一鉱床内に産する黄鉄鉱の結晶構造および表面構造の不均一性について

浮選の立場からみた黄鉄鉱の研究 (第1報)

抄録

Pyrite has been said to have subtle behaviour and important influences on other minerals in flotation process of complex sulphide are “Kuroko”. It is known that pyrite itself has the delicate variations of crystal structure and of material properties including semiconductivity, oxidation nature, and some other chemical and physical characteristics. The study was carried out for the purpose of grasping heterogeneity of inner and surface structure of pyrite causing complicated flotation properties and elucidating the relation between the surface constitution and its flotation activity.
In this paper, pyrite samples from one of the typical Kuroko deposits, the Hanaoka mine in northern part of Japan, were studied from the viewpoints of both crystallographycal and surface topographical aspects. The results obtained are as follows:
1) X-ray diffraction analysis revealed some structural variation of samples whose atomic ratio S/Fe was 2.00-1.93, i. e. 2θ₃₁₁ (target: Co): 66.406-66.495, then d₃₁₁: 1.6334-1.6314Å, the relative intensities e. g. I₂₀₀/I₃₁₁ and I₂₁₀/II₃₁₁ increased with 2θ₃₁₁
2) The observation of the polished surface of samples with reflection microscope showed much variety and heterogeneity of surface appearance, e. g. grain size, and the distributions of pores and pits.
3) The surface stability was studied with phase-contrast microscope and electron microscope using twostage replica of the samples etched by HNO₃ (1+1) for 0.5, 1.0, and 3.0min.
It was made clear that each sample exhibited peculiar distribution of etching structures and the surface was composed of micro mosaic parts whose diameter was of the order of tens to one tenths μ. This fact would explain the heterogeneity of the oxidation property and the reactivity with reagents.
In order to detect the stability difference among different faces, the dominant faces of pyrite a {100}, e {210}, base face a {100} with secondary growth crystals and a {100} of the secondary growth face were etched with HNO₃ (1+1) for 0.5, 1.0, 3.0, and 30.0min., and were observed with electron microscope by the twostage replica method. The test showed that the stability of faces is lowered in the following order, e {210}>a {100}>base face{100}of secondary growth crystals>secondary growth cryStalline face{100}.On the faces of the last two many dislocation figures and peculiar crystalline growth steps were revealed, which means that those faces should be unstable and, therefore, show complex flotation behaviour.
5) The observation of the secondary electron figure with scanning electron microscope. enabled us to get direct information about the surface structure of fine pyrite particles which were significant in practical flotation.