This paper addresses the influence of hydrostatic pressure ($P_{hyd}$) on bubble diameter ($d_b$) and contact angle ($\theta$) of quartz in pure water versus collector solution (Flotigam^® EDA, ${\gamma }_{LG}$ = 57 mN/m) at 20 °C. The pressure range (0–300 kPa) applied against the bubbles’ walls mimics what may happen along the vertical axis of a hypothetical flotation column (HFC) that processes iron ore slurry via cationic reverse flotation of quartz. From the column’s bottom ($P_{hyd}\approx$ 300 kPa) to its top ($P_{hyd}\approx$ 0 kPa), a continuous relief of $P_{hyd}$ occurs steadily. Results indicate that a decrease of $P_{hyd}$ promotes a decrease of θ from 47° to 16° in pure water and from 61° to 42° in the presence of collector. Likewise, $d_b$ increases approximately 60% from the column’s bottom to its top and, consequently promoting an increase in bubble ascending velocity ($v_b$). Values of $v_b$ and $d_b$ were used to assess the bubble Eötvos number (Eo) and the Weber number (We) aiming at characterizing bubble hydrodynamics. It was found that inertial forces dominate surface forces (We > 1) as $d_b>$ 1.86 mm. This dominance constitutes a preliminary indication of a greater likelihood of coarse particles (diameter > 100 $\mathsf{\mu }$m) detaching from bubbles. This situation is typically found in the upper parts of the HFC addressed in this paper.