Processes and systems for producing molten glass using submerged combustion melters, including densifying an initial composition comprising vitrifiable particulate solids and interstitial gas to form a densified composition comprising the solids by removing a portion of the interstitial gas from the composition. The initial composition is passed from an initial environment having a first pressure through a second environment having a second pressure higher than the first pressure to form a composition being densified. Any fugitive particulate solids escaping from the composition being densified are captured and recombined with the composition being densified to form the densified composition. The densified composition is fed into a feed inlet of a turbulent melting zone of a melter vessel and converted into turbulent molten material using at least one submerged combustion burner in the turbulent melting zone.