Three-dimensional topological insulators (3D TI) have conventional parabolic bulk bands alongside protected Dirac surface states. Bi2Te3 materials are promising 3D TI candidates; however, their complex defect chemistry results in a high number of bulk charge carriers dominating transport, even in nanograined forms. To partially manage bulk charge carrier density, this study presents the synthesis of Te-enriched Bi2Te3 nanoparticles. These nanoparticles are then compacted into nanograined pellets with varying porosity to adjust the surface-to-volume ratio, thereby highlighting surface transport channels. The nanograined pellets are analyzed through resistivity, Hall, and magneto-conductance measurements, along with (THz) time-domain reflectivity measurements. Using the Hikami-Larkin Nagaoka (HLN) model, a characteristic coherence length of ~ 200 nm is observed, significantly larger than the nanograins' diameter. THz spectroscopy disentangles the different contributions from bulk and surface carriers, emphasizing the prominent role of surface carriers. These findings strongly indicate that surface transport carriers have surpassed limitations imposed by nanoparticle boundaries.