Stratifier with a pneumatic product recirculation

Claim 2

In a method for separating bulk material mixtures into separated fractions, in accordance with the specific gravities of the mixture components, under the influence of vibrations of a material support carrying the bulk material in a layer and conveying it from an inlet to outlets for separated fractions, and under the influence of aeration by an aeration air current flowing through the material support and the layer, which aeration air current is collected in a hodd covering the material support and is exhausted from the hood: the improvement comprising the steps of providing an additional air current flowing along a path separate from the path of flow of the aeration air current flowing through such layer, the path of flow of such additional air current being completely outside such layer of bulk material; discharging at least one separated fraction of the bulk material, leaving its outlet into such additional air current; thereafter separating the additional air current flow from such at least one separated fraction; returning such at least one separated fraction to such layer; and exhausting the aeration air current from said hood conjointly with exhaustion of the separated additional air current.

Claim 3

A method, as claimed in claim 1, in which the additional air current flows along a path extending from a point below said material support to a point above said material support, and conveys such at least one separated fraction from such point below said material support to such point above said material support; said additional air current flOw being separated from such at least one separated fraction at a point above said material support for flow into said hood.

Claim 4

A method, as claimed in claim 2, including the step of conveying such at least one separated fraction between such point below said material support and such point of separation of the additional air current flow from such at least one separated fraction.

Claim 5

A method, as claimed in claim 2, including the step of returning such at least one separated fraction, after separation of the additional air current flow therefrom, to such layer in the area of the inlet for the bulk material entering the material support for merger with such bulk material.

Claim 6

A method, as claimed im claim 1, in which said aeration air current flowing through such layer is periodically interrupted to provide a pulsating air current.

Claim 7

Apparatus for separating bulk material mixtures, in accordance with the specific gravities of the mixture components, under the influence of vibrations of a material support carrying the bulk material in a layer and conveying it from an inlet to outlets, and under the influence of aeration by an aeration air current flowing through the material support and the layer, which aeration air current is collected in a hood covering the material support and exhausted from the hood, said apparatus comprising, in combination, a porous and gas-permeable material support having an inlet for bulk material and outlets for separated fractions; means operable to feed bulk materials to said inlet; means operable to vibrate said support; a hood covering said support and connected to air exhaust means; a first aeration air inlet arranged beneath said support for flow of the aeration air current for aerating the bulk material mixture flowing over said material support; an additional air inlet separated from said first inlet port; a separate flow duct extending from said additional air inlet port into the range of said material inlet for the flow of an additional air current through said additional air inlet port and through said separate flow duct; means supplying material from at least one outlet to said separate flow duct for entrainment in said additional air current, for return through said separate flow duct to said bulk material inlet; and means in said separate flow duct separating said additional air current from the material supplied thereto, and communicating with said exhaust means for conjoint exhaust of the additional air current with the aeration air current collected under said hood.

Claim 8

Apparatus for separating bulk material mixtures, in accordance with the specific gravities of the mixture components, under the influence of vibrations of a material support carrying the bulk material in a layer and conveying it from an inlet to outlets, and under the influence of aeration by an aeration air current flowing through the material support and the layer, which aeration air current is collected in a hood covering the material support and exhausted from the hood, said apparatus comprising, in combination, a porous and gas-permeable material support having an inlet for bulk material and outlets for separated fractions; means operable to feed bulk materials to said inlet; means operable to vibrate said support; a hood covering said support and connected to air exhaust means; a first aeration air inlet arranged beneath said support for flow of the aeration air current for aerating the bulk material mixture flowing over said material support; an additional air inlet separated from said first inlet port; a separate flow duct extending from said additional air inlet port into the range of said material inlet for the flow of an additional air current through said additional air inlet port and through said separate flow duct; means supplying material from at least one outlet to said separate flow duct for entrainment in said additional air current, for return through said separate flow duct to said bulk material inlet; and means in said separate flow duct separating said additional air current from the material supplied thereto, and communicating with said exhaust means for conjoint exhaust of the additional air current with the aeration air current collected under said hood.

Claim 9

Apparatus, as claimed in claim 6, in which said separate flow duct terminates in such range on said material support covered by said hood; said at least one of said outlets opening into said separate flow duct downstream therein from said additional air inlet port.

Claim 10

Apparatus, as claimed in claim 7, including an injector-like constriction in said separate flow duct between said additional air inlet port and the opening of said at least one outlet into said separate flow duct; said separate flow duct, downstream of said injector-like constriction, increasing in cross sectional flow area.

Claim 11

Apparatus, as claimed in claim 8, including means operable to adjust the flow area of said constriction.

Claim 12

Apparatus, as claimed in claim 7, in which said conveyor line, intermediate the opening of said at least one outlet thereinto and the range of said material inlet, is formed with a flow deflecting portion elevated substantially above said material support; said conveyor line being formed with an air slot beneath said hood and between said flow deflecting portion and the range of said material inlet.

Claim 13

Apparatus, as claimed in claim 7, including a partition positioned between said material inlet and the exit of said conveyor line to said material support.

Claim 14

Apparatus, as claimed in claim 11, in which said partition is curved in the direction of flow.

Claim 15

Apparatus, as claimed in claim 6, in which said separate flow duct forms a pneuMatic conveyor line and is constructed as part of said hood covering said material support.

Claim 16

Apparatus, as claimed in claim 6, including a periodically operable air current interrupter provided in said aeration air inlet.

Claim 17

Apparatus, as claimed in claim 14, including panels subdividing said aeration air inlet into plural flow ducts communicating with said material support; each flow duct having a respective air supply opening; said periodically operable air current interrupter controlling flow of aeration air through said air supply openings and closing said air supply openings at least partially.

Claim 18

Apparatus, as claimed in claim 15, in which said periodically operable air current interrupter comprises a rotating disk having at least one aperture therethrough and positioned opposite said air supply openings.

Claim 19

Apparatus, as claimed in claim 16, in which said rotatable disk has a plurality of apertures therethrough.

Claim 20

Apparatus, as claimed in claim 16, in which said disk is formed as a turbine runner having inclined vanes in said apertures serving to drive said turbine runner by the aeration air flowing through said apertures and said air supply openings.

Claim 21

Apparatus, as claimed in claim 14, in which said air supply means is vibratable with said material support; a vibration-generating motor oscillatably mounted on said material support; eccentric weights rotatable by said motor; a free-wheeling clutch having a driving member and a driven member; means connecting said driving member to said motor for driving thereby; and means connecting said driven member in driving relation with said periodically operable air current interrupter.

Claim 22

Apparatus, as claimed in claim 19, including a first grooved pulley connected to said driven member; a second grooved pulley connected to said periodically operable air current interrupter; an endless drive means interconnecting said grooved pulleys; said pulleys having plural grooves of respective different diameters for adjustment of the transmission ratio between said free-wheeling clutch and said periodically operable air current interrupter.

Claim 23

Apparatus, as claimed in claim 19, in which said means connecting said motor to said clutch driving member comprises a link articulated at one end to said clutch driving member and articulated at the opposite end to said motor.

Claim 24

Apparatus, as claimed in claim 6, including a plurality of individually adjustable baffle plates each in the transition zone from said material support to a respective one of said outlets; and common adjusting means connected to all of said baffle plates for conjoint adjustment of the latter.

Claim 25

Apparatus, as claimed in claim 22, including a respective adjusting shaft secured to each baffle plate; and a respective adjusting plate adjustably secured to each adjusting shaft; said common adjusting means comprising a movable linkage articulated to all of said adjusting plates.

Claim 26

Apparatus, as claimed in claim 23, including spring means maintaining each adjusting plate in adjusted position on its associated adjusting shaft.