Engineering Geology

Engineering Geology

Investigation of the effect of mineralogy in strenghth of schist rocks in Mouteh gold mine

Abstract
In this study, due to the landslide in schist rocks, in the wall of Mouteh gold mines, including of the eastern wall of ChahKhatoon mine, it is important to identify the effective factors. Therefore, due to the diversity of schists in Chah Khatoon and Sanjadeh gold mines (two active mines in Mouteh Complex), to survey the mineralogy of schist rocks in Moteh gold mine has been done by identifying important factors in changes in rock strength. Cosequently, 10 schist samples from walls of these mines were considered for mineralogical, XRD studies. In the next step, these schists were subjected to uniaxial compressive strength (UCS) and Brazilian tests to estimate the mechanical properties and quality of rock mass in different zones of mineral walls. The results showed that the UCS and Brazilian index in these schists are directly and inversely related to the SiO2 and Al2O3 contents of the rocks, respectively, as well as the secondary structures.Some factors such as the presence of secondary structures, continuous surface area, particle size, and mineralogical composition play an important role in the failure modes of these rocks. UCS and Brazilian strength of schists vary from 10 MPa to 72 MPa and 1.9 to 10.2 MPa, respectively. The lowest UCS occurs in strongly weathered rocks with low silica content. However, the type of clay minerals is effective in the stability of the mineral wall. Considering the presence of montmorillonite clay mineral in the eastern wall of Chahkhatoun mine, the rock resistance is moderate despite the high percentage of silica. UCS values of wet and dry rock samples containing muscovite and montmorillonite clay minerals were more different from those of other rocks. In this regard, the rocks with Illite clay minerals are more resistant than Smectite and montmorillonite minerals. In general, the resistance of schists depends on various factors such as mineralogy, which is of great importance because of its involvement in the formation of secondary structures.



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Keywords
mineralogy
uniaxial compressive strength
Brazilian
Montmorillonite and secondary structures
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