Elutriation apparatus and method for cleaning granules

Apparatus for cleaning granules and the like having lighter weight particulate material entrained therewith, comprising:

• (a) a hollow elutriation column,
• (b) injector means for squirting dirty granules on a stream of air into said elutriation column to form a fluidized bed therein at a medial portion thereof,
• (c) electrostatic ionizer means coupled to said injector means and subjecting the dirty granules to bipolar ionization before said dirty granules enter said elutriation column whereby the granules are neutralized and release entrained particulate therefrom.
• (d) suction means for drawing off the lighter weight particulate material from the upper portion of the fluidized bed while allowing the heavier granules to separate therefrom and fall to the bottom of the elutriation column by gravity, and
• (e) means to collect the falling clean granules for re-use,
• said injection means including a conductive tubular member supporting said electrostatic ionizer means and constituting a reference electrode therefor, said electrostatic ionizer means comprising a pair of diametrically opposed static bars having pointed electrodes facing one another within said conductive tubular member, and a high voltage A.C. power supply having a center-tapped-to-ground secondary coil whose opposite sides are coupled to the facing pointed electrodes of the diametrically opposed pair of static bars.

Apparatus for cleaning granules and the like having lighter weight particulate material entrained therewith, comprising:

• (a) a hollow elutriation column,
• (b) injector means for squirting dirty granules on a stream of air into said elutriation column to form a fluidized bed therein at a medial portion thereof,
• (c) electrostatic ionizer means coupled to said injector means and subjecting the dirty granules to bipolar ionization before said dirty granules enter said elutriation column whereby the granules are neutralized and release entrained particulate therefrom,
• (d) suction means for drawing off the lighter weight particulate material from the upper portion of the fluidized bed while allowing the heavier granules to separate therefrom and fall to the bottom of the elutriation column by gravity,
• (e) a U-shaped bend at the top portion of said elutriation column for impeding fine particulate drawn off by said suction means from falling back onto the fluidized bed and recombining with the heavier granules,
• (f) an ambient air inlet intermediate said U-shaped bend and said suction means to facilitate balancing the height of the fluidized bed in said elutriation column, and
• (g) means to collect the falling clean granules for re-use.

Method for cleaning granules having lighter weight particulate material entrained therewith comprising the steps of:

• (a) feeding dirty granules on a stream of bipolar ionized air into a vertically disposed elutriation column to effect neutralization of the granules and the entrained materials so as to produce multi-level fluidization thereof as a floating suspension within the elutriation column,
• (b) drawing off the lighter weight particulate material at the upper portion of the floating suspension by suction,
• (c) allowing the heavier weight cleaned granules to separate from the floating suspension by falling by gravity to the bottom of the elutriation column, and
• (d) collecting the cleaned granules at the bottom of the elutriation column for re-use,
• the stream of bipolar ionized air being produced by exposing the dirty granules to dual phase emission from pairs of facing static bars coupled to opposite sides of a high voltage A.C. transformer so that the emission from one static bar is 180.degree. out of phase with that of the other.

Apparatus for cleaning granules and the like having lighter weight particulate material entrained therewith, comprising:

• (a) a hollow elutriation column,
• (b) injector means for squirting dirty granules on a stream of air into said elutriation column to form a fluidized bed therein at a medial portion thereof,
• (c) electrostatic ionizer means coupled to said injector means and subjecting the dirty granules to bipolar ionization before said dirty granules enter said elutriation column whereby the granules are neutralized and release entrained particulate therefrom,
• (d) suction means for drawing off the lighter weight particulate material from the upper portion of the fluidized bed while allowing the heavier granules to separate therefrom and fall to the bottom of the elutriation column by gravity, and
• (e) means to collect the falling clean granules for re-use,
• said injector means comprising a hollow tube upwardly inclined with respect to said elutriation column and having a port communicating with the interior portion thereof below the level of the fluidized bed whereby falling heavier granules within said elutriation column will be restrained from entering into said injection means.