General Signal Corporation

Pbs Biotech, Inc.

Thomas A Post

Richard A Howk

Ronald J Weetman

J Gregory Zeikus

Kyungnam Kim

Michael A Giralico

Keith E Johnson

Michael J Preston

A pneumatic bioreactor having a containment vessel which includes a semi-cylindrical concavity defined by the vessel bottom. A mixing apparatus includes a rotational mixer rotatably mounted within the containment vessel about a horizontal axis. The rotational mixer has buoyancy-driven mixing cavities which are fed by a gas supply beneath the rotational mixer. The mixing apparatus extends into the semi-cylindrical concavity to substantially fill that concavity. The rotational mixer is divided into two wheels with outer paddles extending axially outwardly and inner paddles extending axially inwardly on either side of each wheel. Blades between the outer and inner paddles form impellers in the wheels to induce axial flow through the wheels in opposite directions. Stationary baffles fixed relative to the containment vessel are inclined toward the rotational mixer in the direction of rotation. The containment vessel may be of film and supported by a structural housing also having a semi-cylindrical concavity defined by the housing bottom.

Pneumatic bioreactor

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. Air or other suitable aeration medium is brought, either under pressure or by suction created by the radial flow impeller, into the space. The aeration medium is radially discharged in the form of bubbles. The axial flow impeller is downwardly pumping and provides a circulation path which sweeps across the bottom of the tank, then upwardly along the sides of the tank returning through the radial discharge of bubbles back into the inlet or suction side of the axial flow impeller. The circulation is limited to the contact zone. A quiet or quiescent zone above the contact zone is left through which the bubbles with attached ore particles can rise without bursting and form the froth containing the concentrated ore for collection.

Mixing system for separation of materials by flotation

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. The enhanced-flow impeller system can be used advantageously in conjunction with an axial flow impeller disposed on a common drive shaft in an upper portion of the tank, to form with enhanced effectiveness a liquid--liquid dispersion as droplets of at least one liquid in at least one other immiscible liquid and to distribute the dispersion uniformly through the tank volume during a dispersion residence time in the tank.

Impeller system and method for enhanced-flow pumping of liquids

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. The enhanced-flow impeller system can be used advantageously to form efficiently and with enhanced effectiveness a liquid - liquid dispersion as droplets of at least one liquid in at least one other immiscible liquid and to distribute the dispersion uniformly through the tank volume during a dispersion residence time in the tank, while avoiding, because of minimization of shear stress on the liquids, the formation of fine (smaller) of droplets of one of the liquids that do no readily separate from the other liquid upon settling.

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Pittsford, NY, United States of America

Thomas A Post