Method and apparatus for mixing

An apparatus for mixing liquids or liquid with particles without entrainment of gas from the liquid surface, said apparatus including a vessel to contain the liquid(s) having an upper end, a lower end and a generally cylindrical containing wall extending between the upper and lower ends, a mechanical turbine for rotation about a generally vertical axis disposed adjacent said upper end and submerged in said liquid adjacent the liquid surface to induce a rotational flow in the liquid(s) that moves radially outward in a generally horizontal plane from the mechanical rotating turbine in a central region of the vessel towards said containing wall to establish a stable swirling flow through the vessel characterised by (i) an outer annular region of moderate rotational flow around said vertical axis adjacent the containing wall moving from the upper end toward the lower end so as to maintain a continuous flow of liquid over the containing wall, (ii) an inward flow adjacent the lower end of the vessel, and (iii) an inner core region of rapid rotational flow around said axis about the central region of the vessel moving from the lower end toward the upper end and extending from substantially adjacent the lower end of the vessel to the mechanical turbine.