Method and apparatus for storing and unloading bulk material

Bulk storage and unloading apparatus for handling a selected granular material having a predetermined angle of repose and including:

• storage means including a substantially horizontal bottom wall having upstanding opposite end walls and at least one side wall rising upwardly therefrom to form a storage compartment;
• discharge means in said bottom wall and spaced from said side wall a distance sufficient to cause said material, when draining hereinto under the influence of gravity, to form an angle of repose leading upwardly therefrom to a selected level at said side wall;
• a bladder device including a liner extending substantially the full length of said compartment affixed at one edge to said side wall at substantially said selected level or thereabove, normally hanging down along said side wall and then projecting outwardly along said end and bottom walls to said discharge means, said bladder device being shaped to assume a loaded configuration lining said bottom end and top walls and to assume an unloaded configuration bulging outwardly from said side wall and turning downwardly to project to said discharge means;
• fastening means affixing the marginal edges of said bladder device to said bottom wall adjacent said discharge means;
• pressurizing means for pressurizing said bladder device to progressively balloon the upper portion of said bladder device outwardly away from said side wall to roll the uppermost material resting against said bladder outwardly away from said side wall and to then, upon continued inflation, progressively continue bulging said bladder outwardly at its upper portion to continue rolling said material outwardly away from said side wall toward said discharge means to finally bulge the bottom portion of such bladder device away from said side and bottom walls to assume said unloaded position.