Blender for pneumatically mixing batches of dry granular materials by tumbling

In an air blender for pneumatically mixing together dry granular materials comprising a vertically oriented elongated container having an input opening at the top for inputting granular materials to be mixed, cylindrical side walls, a normally closed central discharge opening at the bottom, lower walls sloped inwardly from the bottom of the cylindrical walls to said discharge opening, and an air manifold surrounding said discharge opening having an inner air chamber containing pressurized air, the improvement comprising:

• a series of air nozzles in the manifold equally spaced around the discharge opening for providing air communication between the inner air chamber of the manifold and the interior of the container, said nozzles oriented at an angle to direct the pressurized air generally parallel to the longitudinal axis of the container;
• means for repeatedly opening and closing said nozzles;
• a source of pressurized air;
• conduit means for delivering pressurized air from said source of pressurized air to the inner chamber of the manifold;
• and
• adjustable throttling valve means located in said conduit for controlling the air flow into the manifold inner chamber from said pressurized air source when said nozzles are opened.