Mineral composition and niobium and tantalum occurrence states in Tudiling Nb−Ta Deposit, Zhushan County, Hubei Province

The Tudiling Nb−Ta Deposit is a large-scale Nb−Ta deposit newly discovered in Hubei Province in recent years. However, its fundamental mineralogical studies, including mineral composition, grain size and embedding characteristics of Nb−Ta minerals, and their occurrence states, remain relatively weak, which severely constrains the efficient resource evaluation and rational development and utilization of this deposit type. The study systematically investigated its process mineralogy by using microscopy, X-ray diffraction, and mineral liberation analysis. The results show that the Nb−Ta ore can be classified into two lithologies: trachytic tuff and tuffaceous sericite phyllite, with Nb₂O₅ grades of 0.157 % and 0.114 % and Ta₂O₅ grades of 0.012 % and 0.006 %, respectively. The two rock types share similar mineral compositions, with niobium and tantalum mainly occurring in columbite-tantalite and niobian rutile, and minor betafite observed in the tuffaceous sericite phyllite. Niobium and tantalum predominantly occur as independent minerals in columbite-tantalite, and secondarily in the form of isomorphism in niobian rutile. The Nb−Ta minerals generally have fine embedding particle sizes with low liberation degrees. The vast majority of grains have liberation degrees of less than 25 % and mainly exhibit two- or multi-phase intergrowths with albite and muscovite, which makes mineral processing rather difficult. The research findings provide a critical scientific basis for subsequent resource development, utilization, and optimization of mineral processing technology.