FR2535622A1 - IONIC BOMBING ELECTRODYNAMIC SEPARATOR FOR SEPARATING SOLID PARTICLES - Google Patents

Abstract

THE PRESENT INVENTION CONCERNS ELECTRODYNAMIC SEPARATORS WITH ION BOMBARDING. THE SEPARATOR OF THE INVENTION CONTAINS A ROTARY SUPPORT CYLINDER 10 AND A GRID PLATE 28 WITH A PLURALITY OF IONIC DISCHARGE ELECTRODES 24 ARRANGED AT A CERTAIN DISTANCE OPPOSITE THE SUPPORT CYLINDER AND COVERING A SURFACE SUBSTANTIAL OF THIS. A FLOW OF SOLID PARTICLES IS SPILLED OVER AN UPPER QUADRANT OF THE SUPPORT CYLINDER 10 AND SUBJECTED TO IONIC BOMBARDING DURING ITS PASSAGE THROUGH THE CYLINDER AND OVER A CERTAIN DISTANCE AFTER LEAVING THIS ONE, THANKS TO THE REQUIREMENTS THAT ARE NOT CONDUCTED TO 36 THEIR ION CHARGES ARE ATTRACTED BY THE GROUNDED SUPPORT CYLINDER 10, WHILE THE CONDUCTIVE PARTICLES 38 QUICKLY SEND THE IONS RECEIVED ARE LESS ATTRACTED BY THE SUPPORT CYLINDER 10 AND FALL IN FREE FALL. A SCRAPER 18 SCRAPS THE NON-CONDUCTIVE PARTICLES ADHESIVE TO THE SURFACE OF THE SUPPORT CYLINDER 10, AND AN ADJUSTABLE MOBILE SHUTTER ALLOWS TO DEFINITELY SEPARATE THE ESSENTIALLY NON-CONDUCTIVE PARTICLE FLOW 36 FROM THE ESSENTIALLY CONDUCTIVE PARTICLE FLOW AND THIS SUPPORT 38. HAS A SECOND OPERATION OF THIS TYPE, WHEN IT STILL CONTAINS A CERTAIN NUMBER OF NON-CONDUCTIVE PARTICLES. THE INVENTION MAY BE USED TO SEPARATE SAND, GRES AND FINE CONTAINED IN A FLOW OF WOOD CHIPS.

Description

The present invention relates to the field

  general principle of separation into

  These particles are solid by subjecting the particle stream to ionic bombardment, whereby a number of particles of a relatively electrically nonconductive nature receive and retain an ionic charge while the other particles in the stream are ionically bombarded. which are relatively conductive in nature give up or dissipate all the ions received, even though in this case it is a bombardment process

  ionic, it is traditionally in the classi-

  general application of electrostatic separations, such as

  that: dielectric separation, migration of electric charges

  by the fact that the ion bombardment process is electrodynamic in nature, since

  produces an effective flow of ions from the

Gee.

  Although at present there are

  of all these processes, an optima

  ionization process is lacking, so that the present invention fills this gap

  by providing a process that subjects the flow of particles

  the solids to a substantially uniform ion flux emitted by a plurality of discharge electrodes covering a substantial area of the solid stream as it flows onto the surface of a grounded support cylinder and falls into free fall between

  this surface and a curvilinear grid enveloping

  and at a certain distance the surface of the

  support cylinder, the plurality of electrode electrodes

  ionic charge located on this grid.

  In the current technological state, the ionic bombardment apparatus first discharges the flow of solid particles onto the surface of a rotating support cylinder while an essentially point source of ions is directed at the material. Solid during the flow thereof on the surface of the support roll.

  positive results, however, it is relatively ineffi-

  cace, since it requires the support drum to rotate at a relatively low rotational speed, while the relatively low force of the ions bombarding the flow of solid particles spilled onto the surface of the support cylinder prevents good separation of non-conductive particles from particles

conductive.

  Therefore, it is an object of the present invention to optimize the process of separating into several fractions of a stream of solid particles by briefly contacting the stream of solid particles with only a small portion of the surface.

  of the support cylinder, and then allowing immediate

  the material to fall freely into the free space between the support cylinder and

  the grid containing a plurality of electrode electrodes

  Ionic Charge Subjecting the flow of solid particles to a free fall contributes to separating the two particle fractions by subjecting them much more efficiently to the ionic field and thus increasing the separation efficiency. The invention is particularly suitable for the separation of the fine reshaped with the wood, and more particularly with the non-wood chips

  sifted having a moisture content of up to about 55%.

  By feeding the stream of solid particles falling in free fall between the surface of the cylinder of

  rotating support and the grid containing the electro-

  The non-conductive particles that acquire a charge can easily be attracted to the lower potential of the grounded support cylinder. These nonconductive particles move toward the support cylinder, and they attach themselves to the support cylinder.

  on the surface of it or they fall down.

  The particles attached to the surface are scraped off, but in any case the non-conductive particles are forced to separate from the falling flow in free fall under the effect of their electric potential.

  compared to the support cylinder grounded by

  these particles are directed to a place distinct from that where the flow of particles

  in free fall constituted by the other particles,

  ductors, which fall essentially vertically under the effect of their momentum and the strength of their

gravity.

  A movable shutter arranged in the upper part

  a trap flap interferes with the falling flows of the two fractions of solid particles at a place where non-conductive and conductive particles have already

been separated.

  Then, the flow of conductive particles is directed on the surface of a second support cylinder disposed below the first support cylinder, and on this second support cylinder is repeated essentially

  the same process, and the non-particle

  separated conductors during this second operation

  with the non-conductive particles of the first

  ration, thereby increasing the separation efficiency into a nonconducting particle stream and a flow of conductive particles. Therefore, this apparatus

  requires a lower energy consumption for

  hold the ion flux field, for example of the order of magnitude of about 50 watts per meter length of

  the contact surface between the particles and the cylinder

  dre de support And-given the presence of adjustable movable flaps arranged in the upper part of the respective hatches and used to separate the two separate particle streams during each operation, it is easy to adjust the efficiency of the separation,

  hence, it results in great flexibility of operation.

  On the other hand, given the non-conductive properties of sand and sandstone, this apparatus using the principle of ion bombardment is particularly suitable for the treatment of wood chips in order to

  separate sand, sandstone and fines.

  Therefore, it is an object of the present invention to provide apparatus based on the principle

  ion bombardment in order to increase the effi-

  separation efficiency into two distinct fractions of one

  flow of non-conductive solid particles and conductive

  facilitators. It is another object of the present invention

  to provide equipment based on the principle of

  ionic cladding and-enclosing a plurality of electro-

  ionic discharge at a certain distance

  of the surface of the rotating support cylinder leaving

  enough space to allow a flow of particles

  falling in free fall to go.

  It is another object of the present invention

  to provide a separation apparatus of parti-

  ions by ion bombardment in which the conductive fraction of the solid particles is subjected a number of times to the ion bombardment process in order to further increase the efficiency

overall apparatus.

  These and other objects, features, and benefits of the device will become more apparent

  thanks to the description of the preferred embodiments

  detailed below and with reference to the accompanying drawings, in which Figure 1 is a schematic side view of the apparatus, showing the location of the ion discharge electrodes with respect to the flow of the falling stream of solid particles, and FIG. 2 is a slightly enlarged view of a portion of the apparatus shown in FIG.

  with indication of the resulting force vectors

  different distinct particles, one of which

  is closer and the other farther away from the over-

face of the support cylinder.

  In the apparatus shown in FIG. 1, a stream of incoming solid particles 20 to be separated into two fractions is conveyed by the feed deck 14, which may be of the vibration type, in the direction of the arrow 21. on the peripheral surface of the support cylinder 10 which rotates in the direction of the curved arrow The surface of the support cylinder is

  connected to the potential of the earth thanks to the device 11.

  The flow of solid particles, incoming; for example, wood chips containing fines, sand, sandstone and other similar materials that are to be separated,

  is briefly brought into contact and transported by a

  upper circumference of relatively small area of the rotating surface of the support cylinder, then

  falls to a more or less free fall according to a

  jectory determined by the force of gravity and the momentum of the respective particles A grid plate 28 is disposed at a distance from

  a surface portion of the support cylinder 10, the

  the grid is sufficient to allow the falling solid material to pass freely between the support cylinder and a plurality of ion discharge electrodes 24 arranged in the grid plate. This grid plate can be hinged, as shown in the figures, or curvilinear, but in any case it covers approximately one-sides of the support cylinder, its lower part being oriented substantially vertically so as not to geyser the fall of the

  conductive fraction of the solid material.

  A source of high voltage direct current

  16 (eg about 40 to 60 kV) is connected to the

  than grid with a potential just below the point of sparking, where it results in an ion flow

  emitted by the ion discharge electrodes 24, constitute

  killed preferably of negative ions indicated schematically

  by lines 27, the flow of ions being essentially oriented

-6

  radially towards the perimeter surface

  of the support cylinder 10 for the purpose of

  cepter, that is to say "bombard" the solid particles poured on this surface These ions move in the direction of the maximum voltage gradient existing between

  electrodes and the support cylinder.

  Roughly speaking, solid particles are

  may be classified as non-conducting particles

  these and conductive particles, and thus it is meant that the non-conductive particles tend not to

  conduct electrical charges, while

  However, conductive substances tend to lose

  to dissipate any electric charge they are likely to

  able to receive In the ion bombardment apparatus

  designed and constructed in accordance with the present invention, the

  solid particles are exposed to the ionic flow by colliding

between the two flows.

  As shown in FIG. 2, the non-conductive particles 36 having received an ionic charge have

  tend to show an affinity for the surface of the cylinder.

  dre de support 10 grounded, and they attach themselves to the surface of it or simply dump underneath it under the effect of their attraction from with the support cylinder. either, these particles are directed to the left of an adjustable movable flap 22, either they are scraped from the surface of the support cylinder by the scraper 18, or they fall more or less freely below the cylinder

  of support 10 after having been deflected

curved roof.

  On the other hand, the conductive particles 38 having relatively quickly given up any charge received from the bombardment ions maintain a relatively unaffected descent trajectory by moving from the surface of the upper quadrant of the support cylinder 10, and consequently they fall. to the right of the adjustable movable flap 22 and move the -7-

  along the top hatch 34.

  Factors exerting an influence on the effi-

  separation efficiency of the solid particles, and hence the overall efficiency of the process are: 1) the applied voltage, 2) the moisture content of the particles, 3) particle size, 4) the position of the

  adjustable movable flap, and, 5) the feed rate.

  With regard to the applied voltage, as the voltage increases, the strength of the electric field increases and a greater force is exerted on each particle concerned, thus causing movement over a greater distance. in moisture, a higher force is needed to move a concerned particle of some

  size when the moisture content is higher.

  As far as particle size is concerned, the larger particles tend to maintain their initial trajectory as they pass through the apparatus, while the smaller particles exhibit a more pronounced displacement in

  direction of the support cylinder The movable damper

  (described in more detail in the following) constitutes

  a mechanical method of adjusting the

  flows between conductive and non-conductive

  As far as the feed rate is concerned, the overall separation efficiency decreases when the feed rate is increased. Therefore, a uniform distribution over the entire width of the cylinder

  support is important.

  FIG. 2 also shows the resultant force vectors 44, 46 respectively acting on two non-conducting particles 43, 45, these vectors resulting from the vertical force due to the gravitation and the momentum and to the lateral force due This also shows how the resulting force acting on each particle is a function of their velocity and position in the ionic force field. Their velocity is in part a function of the angle at which the feed 14 conveys the solid material entering the surface of the support cylinder If the angle is too small, the solid material will hit the grid and will cause un-desirable wear of the ion discharge electrodes If the angle is too high, the solid material,

  including fine conductive particles, will have

  this to accumulate on the surface of the support cylinder and to acquire the same load as the cylinder grounded so to be reapplied by the electrodes of

  ionic discharge, thus reducing the effectiveness of

ration.

  In the apparatus of Figure 1, the

  The scraped non-conductive layers of the support cylinder 10 or dumped thereunder move along the upper delivery trap 40 downwardly and bypassing the rear face of a second support cylinder 12 which is disposed therein. below the first support cylinder 10 Analogously, the particles

  conductors move along the hatch of

  34 downwardly and pour over a second feed deck 48 disposed below so as to be able to discharge the conductive particles on the surface of the upper dial of the second support cylinder 12 in a similar manner to which the material

  incoming solid is poured onto the support cylinder 10.

  A grid plate 30 is disposed around the upper and lower quadrants of the front face of the support cylinder 12, and is spaced from the surface thereof to define a space in which the falling particles are exposed to a surface.

  plurality of ionic discharge electrodes 26

  by a high voltage direct current source 17 in a manner similar to that described for the upper support cylinder 10 and the gate plate

superior 28.

  The fraction of solid particles pouring between the grid plate 30 and the support cylinder 12

  which is the fraction of particles

  However, the materials rejected by the support roll 10 contain a certain proportion of non-conductive particles which could not be separated in the step.

  Therefore, under the influence of

  27 ion bombardment charge emanating from the electrodes 26, all the non-conductive particles retained in the preceding conductive particles fraction are attracted towards the support cylinder 12, on the surface of which they adhere and are subsequently scraped by the wiper 19, or instead of adhering to the surface of the cylinder they are simply deflected due to the attraction exerted by the support cylinder 12 which is grounded by the device 13, and they are poured to the left of the adjustable movable flap 23 In any event, they fall on the lower routing hatch for the non-conductive particles 42 o they are united with the nonconductive particles

  previously separated and spilling along the trap-

  eg higher routing for non-con-

  The fraction of solid particles containing above all conductive particles and therefore being substantially relatively unaffected by the

  bombardment of ions in its path from the cylinder

  12 and in its trajectory of free fall moves along the lower hatch 35, discharging

  finally on the escape hatch 50.

  Thus, the particles transported by

  escape hatches 42 and 50 for non-particulate

  conductive and conductive respectively are almost completely separated into two respective fractions, one consisting of non-conducting particles and

  the other consisting of conductive particles

  initially the flow of solid particles entering

  on the surface of a support cylinder and allowing

  - putting after a very short time to fall freely on a relatively large height while

  breaking along a plurality of electrode electrodes

  ion charge arranged in the vicinity of one side of the peripheral surface of the support cylinder, the

  conductive particles separate from the particles con-

  conductors, and these are subject to the ion bombardment process for a relatively short period of time.

  prolonged This prolonged treatment followed by a -

  second ion-bombardment step analogous to the

  first, greatly increases the degree and effectiveness of

  cited the separation of solid particles.

he

Claims (6)

CLAIMS:   1 Electrodynamic separator of the bomb-type   ion separator for separating a stream of solid particles (20) into a fraction of conductive particles (38) and a non-conductive particle fraction (36), the separator enclosing a grounded support cylinder (10) and a feeding apron (14) conveying the solid material, characterized in that the feeding apron (14) is constructed and arranged to discharge the solid material on a quadrant-upper of the surface of the support roll ( 10); and characterized by enclosing a gate plate (28) having a plurality of ion discharge electrodes (24) energized   by a current source and arranged at a certain distance   it vis-à-vis a portion of the peripheral surface of the support cylinder (10), thereby defining a space   allowing the passage of solid particles and the bom-   ionic coating of these during their displacement on the support cylinder (10) and during their fall started as soon as they left the support surface, thanks to which the solid particles are subjected to ion bombardment over a certain height of their path in the vicinity of the support cylinder (10) and in the vicinity of the ion discharge electrodes, the non-conductive solid particles receiving and maintaining an ionic charge and being therefore attracted by the support cylinder (10), and the solid particles conductors losing or dissipating any load they may have received and continuing their free fall path initiated from the moment they pass over the support cylinder (10); and in that it encloses separation means (22) disposed below the location where the solid material passes between the support cylinder (10) and the ion discharge electrodes (24), by virtue of which the non-solid fraction -conducting particles falls to one side, and the conductive fraction   particles fall on the other side of the separation means 12 -   ration (22), thus being able to be separately collected.   Separator according to claim 1, characterized   in that the orientation of the feed deck (14) can be adjusted so that the solid material does not touch a relatively small portion of the peripheral surface of the support roll (10) until the solid material (20) leaves this surface and then drops freely between the support roll (10) and   the ion discharge electrodes (24).   Separator according to claim 1, characterized   in that the ion discharge electrodes (24)   connected to a high voltage power source   tinu (16), whereby the electrodes (24) generate an ionic force field between themselves and the surface of the support cylinder (10).   Separator according to claim 1, characterized   characterized in that the ion discharge electrodes (24) are arranged in a grid plate (28) located substantially opposite the peripheral surface of the support cylinder (10) and which extends in the vertical direction, thereby defining an ion bombardment space substantially covering a surface from where the solid material (20) contacts the support cylinder (10) to where the separation means (22) intersects the particles falling more or less vertically.   Separator according to claim 1, characterized in that the separating means (22) contain a adjustable movable flap.   Separator according to claim 1, characterized   in that it further contains a second support cylinder (12) grounded and disposed below the   first support cylinder (10) and allowing reception-   the fraction of conductive particles (38) is   health of it; a plurality of ion discharge electrodes (27) powered by a current source and   disposed at a distance from the sur-   13 - peripheral face of the second support cylinder (12), thereby defining a second space allowing the passage of the fraction of conductive particles received from the first support cylinder (10) on the support cylinder (12), which solid particles are subject to a second ion bombardment during their passage   on the support cylinder (12) and during their   that they follow after leaving the surface of   this cylinder, so that the non-conductive particles   waste (36) receive and maintain an ionic charge and are attracted to the surface of the   second support cylinder (12) and the particles   ductors (38) continue in their free fall trajectory under the effect of the gravitational force and their momentum; and second separation means (23) disposed below the second support cylinder (12)   and to intercept separately the flow of   non-conductive cells (36) and the flow of conductive particles (38), and to collect these two fractions separately.   Separator according to claim 6, characterized   in that the flow of non-conductive particles from   of the first support cylinder (10) and the flow of parti-   non-conductive cells from the second support cylinder (12) are collected together.   By proxy of BELOIT CORPORATION The proxy holder is R Baudin