Bolshetagninskoe deposit is one of the most important Russia niobium potential sources. It is confined to carbonatite complex of the same name that is situated in the Sayan Mountains, Eastern Siberia. In the result of VIMS exploration niobium ores reserves have been applied by Russian State Reserve Committee in 2012 year. Ores contain about 1% Nb2O5 and are unique in that the economic pyrochlore mineralization is concentrated in alkaline metasomatic rocks but not in carbonatites[1]. During exploration 47 borehole samples and 6 bulk samples were collected and studied by process mineralogy techniques (optic mineralogical analyze, optic image analyzer system, XRD, EPMA). 26 borehole samples and 2 bulk samples were tested by rougher floatation to define geometallurgical items and to understand the ore’s behavior. Four volumetric samples have been tested by commissioned flowsheet (radiometric separation → impact milling → selective floatation → pyrochlore leaching → ferroniobium). There are three ore types in the Bolshetagninskoe deposit: microcline-pyrochlore (MP), biotite-columbite-pyrochlore (BCP) and carbonate-pyrochlore (CP). MP type is the most important one. MP ore consists of microcline (59wt%–70wt%) with minor carbonates, apatite, sulfides, goethite. Pyrochlore, the essential Nb mineral (94% of ore Nb content), occurs as fine grains (weighted average grain size is 57 μn). Since pyrochlore grains are fine and friable, the ore preparation size and method is a main problem of its treatment. While primary ore processing is effective to remove about 30% waste material it is important to evaluate its influence on floatation feed grade. Bolshetagninskoe deposit is one of the most important Russia niobium potential sources. It is confined to carbonatite complex of the same name that is situated in the Sayan Mountains, Eastern Siberia. In the result of VIMS exploration niobium ores reserves have been applied by Russian State Reserve Committee in 2012 year. Ores contain about 1% Nb2O5 and are unique in that the economic pyrochlore mineralization is concentrated in alkaline metasomatic rocks but not in carbonatites. [1]. During the exploration 47 borehole samples and 6 bulk samples were collected and studied by process mineralogy techniques (optic mineralogical analyze, optic image analyzer system, XRD, EPMA). 26 borehole samples and 2 bulk samples were tested by rougher floatation to define geometallurgical items and to understand the ore’s behavior. Four volumetric samples have been tested by commissioned flowsheet (radiometric separation → impact milling → selective floatation → pyrochlore leaching → ferroniobium). There are three ore types in the Bolshetagninskoe deposit: microcline-pyrochlore (MP), biotite-columbite-pyrochlore (BCP) and carbonate- pyrochlore (CP). MP type is the most important one. MP ore consists of microcline (59 wt% Pyrochlore, the essential Nb mineral (94% of ore Nb content), occurs as fine grains (weighted average grain size is 57 μn). Since pyrochlore grains are fine and friable, the ore preparation size and method is a main problem of its treatment. While primary ore processing is effective to remove about 30% waste material it is important to evaluate its influence on floatation feed grade.