Abstract: In order to sparge gas into a liquid or liquid suspension in a tank wherein a principally axial flow pattern downwardly towards the bottom of the tank and then upwardly along the side wall of the tank returning axially downward is established by an axial flow impeller, a disc of a diameter less than the diameter of the impeller is spaced axially therefrom in the direction of the outlet flow towards the bottom of the tank from the impeller so as to turn the axial flow, radially, thereby establishing a pressure gradient which prevents the collection of gas released by a sparge between the disc and the bottom of the tank and flooding of the impeller. The gas is released in the axial flow from the tip region of the impeller thereby facilitating the shearing of the gas into fine bubbles promoting mass transfer of the gaseous phase into the liquid phase in the tank. Since flooding is inhibited, as much as six times the volume of gas (gas rate) can be handled as may be the case without the disc.

Abstract: A mixing system in a tank provides a flotation cell for froth collection of minerals such as metallic ores thereby separating such ores from other materials with which they are mined and enabling a concentrated ore component to be collected. The mixing system maintains particles containing the ores in a circulating liquid suspension in a contact zone where bubbles are discharged. Ore particles are attracted and attached to the bubbles. The bubbles rise and float to the top of the liquid for collection of the concentrated ores. The mixing system includes a radial flow impeller and an axial flow impeller which are attached for rotation on a common shaft, with the axial flow impeller below the radial flow impeller. The radial flow impeller is disposed in a space between a disc, which rotates with the radial flow impeller and another disc which is stationary, and may be a flange of a pipe around the shaft and extending above the surface of the liquid.

Abstract: In order to efficiently mass transfer from gas, particularly air, into liquid or liquid suspensions with enhanced efficiency in terms of the mass of the gas transferred to the liquid, the gas is released or sparged through a plurality of open pipes which are disposed in a space between the bottom of the tank containing the liquid or liquid suspension and an axial flow impeller which creates a flow path downwardly past the outlet ends of the pipes. Turbulence is enhanced even though the air leaves the pipes at low velocity rather than in a jet through the use of a Bernoulli air trapping ring and plates. The ring and plates encounter the flow produced by the axial flow impeller successively. The ring distributes the air and assists in defining a low pressure region below the ring. A low pressure region also is defined by the plates on the underside thereof. The underside of the plates is in the vicinity of the outlets of the pipes.

Abstract: A rotatably driveable enhanced-flow impeller system is provided for pumping at least one liquid in a tank through an outlet port thereof. A radial flow impeller has a first impeller face disposed proximate the bottom of the tank and proximate or extending into an inlet port for liquids in the tank bottom. The radial flow impeller has a plurality of blades with radially outermost blade tips terminating along a blade terminating circle. Disposed adjacent a second opposing face of the radial flow impeller is a radial flow extension plate which preferably extends radially outwardly along the second face by a radial distance beyond the blade terminating circle. The radial flow extension plate may be fixedly attached to the second impeller face.

Abstract: A rotatably driveable enhanced-flow impeller system has a radial flow impeller with a first impeller face disposed proximate the bottom of the tank and proximate or extending into an inlet port for liquids in the tank bottom. The radial flow impeller has a plurality of blades with radially outermost blade tips terminating along a blade terminating circle. The blades and inlet port are contoured to reduce shear stress on the liquids. Disposed adjacent a second opposing face of the radial flow impeller is a radial flow extension plate which preferably extends radially outwardly along the second face by a radial distance beyond the blade terminating circle. The radial flow extension plate may be fixedly attached to the second impeller face.

Abstract: In order to circulate a two-phase system (a suspension of solid particles in liquid) in a large (e.g., 100 ft. diameter) and shallow tank (e.g., where the liquid level, Z, to tank diameter, T, ratio is 0.4), a cluster of side entering mixers is used and a desired flow pattern (much like that obtained from a top entering mixer) along the bottom and top of the material in the tank and vertically along the walls of the tank is obtained by (a) rotating an end mixer in the cluster in opposite sense to the other mixers, (b) spacing the mixers so that the interference is reduced between the flow produced by the mixers at the wall of the tank opposite from the mixers, and (c) by tilting the mixers so that the flow intersects the bottom near the wall of the tanks opposite from the mixers.

Abstract: In order to obtain efficient gas dispersion (aeration where air is the gas) in mixing systems where the circulating impeller is offset from the center of the tank containing the medium in which the gas is dispersed or sparged while being circulated, flooding of the impeller due to entrainment of gas released by the sparging device (a pipe or ring having as outlets) because of the asymmetrical return flow of the medium circulating in the tank which entrains the gas and brings the gas into the area swept by the impeller as it rotates, is avoided by arranging the sparging device to prohibit the release of gas into a region, including a sector of the swept area, where the return flow responsible for flooding occurs. This sector has been found to lie along a line between the center of the tank and the axis of rotation of the impeller. The gas dispersion mixing system is especially useful in dispersion of gas into large volumes (e.g. 20,000 cubic feet).

Abstract: Side entering mixer apparatus has an impeller with an axis of rotation above and along the bottom of a tank in which the material (liquid or liquid suspension) to be mixed is disposed. In a discharge region in front of the impeller and in close proximity to the front of the impeller, there is disposed a flow straightening vane which removes substantially any radial component of flow. By removal of the radial flow component, helical flows which interact in the discharge region and cause pulsation of flow into the inlet region (between the rear surface of the impeller and the side wall of the tank from which it projects) are substantially eliminated and potentially catastrophic stress-induced failures in the side entering mixer and its seals are avoided.

Abstract: A mixer impeller made up of paddle shaped blades, which near their tips (e.g., at 90% of the radius of the impeller from its axis of rotation) are of a width at least 40% of the impeller's diameter. The blades also having camber and twist. They are formed by establishing bending moments which form the blades into sections which are curved and flat, with the flat sections being at least in the center area of the base of the blades.

Abstract: The gas outlet of a pipe or other sparging device is encompassed by a cover or cap which is located between the gas outlet and the mixing impeller at the bottom of a vessel. The cap is closed at the top and has a side wall so that the gas bubbles disperse around the lower rim of the wall. The wall may be non-symmetric, such as square in cross section, so as to be at different radial positions with respect to the gas outlet. The gas bubbles, even if released in pulses are distributed spatially and in time. The lower rim is preferable serrated (as a saw tooth edge) with the teeth being of different height, thereby further spreading the distribution of the bubbles as they are dispersed. The overlap or distance between the rim and the gas outlet is such that a sufficient quantity of gas is confined around the outlet to damp pressure pulsations when the pressure of the gas at the outlet does not significantly exceed the hydrostatic pressure at the outlet into the liquid.

Abstract: A mixer which provides axial flow in a non-uniform flow field, such as may be established by gas which is sparged into a medium being mixed in a tank, and provides large axial flow volume without flooding and withstands variable loads on the blades thereof, thereby providing for reliable operation. The mixer impeller is made up of paddle shaped blades, which near their tips (e.g., at 90% of the radius of the impeller from its axis of rotation) are of a width at least 40% of the impeller'a diameter. The blades also having camber, twist and flat sections. The flat sections being at least in the center area of the base of the blades. The hub for attaching the blades to the shaft of the mixer has radially extending arms with flat surfaces. The base of the blades are spaced from the shaft to define areas therebetween.