Gas dispersion in horizontal pulp-fibre-suspension flow

► Gas dispersion for injection into dilute horizontal pulp flow was similar to that in water. ► Bubbles in dense fibre networks concentrated near the pipe wall at high gas velocity. ► Fibre networks created pulp slugs at the top of the pipe for buoyancy-dominated flow. ► Mixing was less dependent on suspension velocity at higher fibre mass concentrations.. ► Gas mixing was almost independent of injection tube length and diameter.