US1994610A - Abrasive separating and cleaning apparatus - Google Patents

Description

March 19, 1935. R. B. HUYETT ABRASIVE SEPARATING AND CLEANING APPARATUS Filed May 22. 1930 4 Sheets-Sheet 1 .eeeevooou am mg March 19, 1935. R. B. HUYETT ABRASIVE SEPARATING AND CLEANING APPARATUS Filed May 22, 1930 4 SheetsSheet 2 March 19, 1935. R. B. HUYETT 1,994,610

ABRASIVE SEPARATING AND CLEANING APPARATUS Filed May 22, 1950 4 Sheets-Sheet s March 19, 1935. HUYETT 1,994,610.

ABRASIVE SEPARATING AND CLEANING APPARATUS Patented Mar. 19, 1935 ABRASIVE SEPARATING AND CLEANING APPARATUS Robert B. Huyett, Hagerstown,,Md., assignor to Pangborn Corporation ;Hagerstown, Md., a

corporation of Maryland :Application May 22, 15:21), Serial No. 454,780

' 9 Claims. (01. ace -s3) The invention relates to anapparatus for reclaiming abrasive which has been used in sand blast apparatus for cleaning castings and in similar operations in which the abrasive which is usually hard metal in granular form, though it may be sand, grit or shot, or any material of a granular nature, is projected at high speed, as by means of compressed air, against the surface of the castings or other articles to be cleaned.

After being used in this way the abrasive is mixed with dbris as nails, wire slugs and foundry sand, core sand and fine dust. The reclaiming process consists in separating the abrasive from the debris and cleaning it. e

The apparatus as illustrated comprises a rotary screen device by means of which the coarser dbris as nails, pieces of wire, slugs and chips and thelike, are separated from the finer materials including the abrasive, the operation being preferably continuous, the coarser dbris thus separated being discharged by way of one chute while the abrasive and finer particles are delivered by way of another chute to a hopper from which it'may be fed to a pressure tank or to an air washer in which the dust and sand and other foreign particles are separated from the granular abrasive which is thus reduced practically to its original condition, the variation of the momentum between the different particles in addition tothe, air'draft, being utilized in this con nection.

In the accompanying drawings I have illustrated an apparatus embodying the features of the invention in the preferred form.

In the drawings:

, Figure 1 is a side elevation of the screen member looking in the direction of the axis, a portion of the side wall being broken away to show the internal construction.

Figure 2 is a section on the line 2, 2 of Figure 1 more or less of a diagrammatic nature in that the 1 chutes on both sides of the section are shown.

Figure 3 is a detail view of one of the screen 4 corners in the nature of a section on the line 3, 3

Figure 2. Figure 4 is a side elevation showing the complete apparatus assembled.

Figure 5 is a side elevation looking from the left of the apparatus as seen in Figure 4.

Figure 6 is a top plan view of the same. Figure 7 is an elevation corresponding to Figure 4, showing the air washing apparatus'with the screen omitted, in a slightly different form. Figures 8 and 9 are diagrammatic views showtary screen 1 or used abrasive with the various kinds of dbris, sand and dust described, from ing the stratification of the materials by momentum.

Referring to the drawings by numerals, each of which is used to indicate the same or similar parts in the different figures, the apparatus as 5 shown comprises a rotary screen 1, to which the used abrasive to be cleaned or reclaimed is fed by way of a chute 2, which receives the material from any suitable source, as elevator 3. The screen member 1 as seen in Figure 1 is driven in right handed rotation and the chute 2de1ivers the material to be treated to the screen at a point near the beginning of the lower 180 arc of the traverse of the screen pockets or elements 4, to be described, The screened material is delivered throughout the lower half of the arc of rotation and the larger debris, nails, wires, slugs, chips, etc. is discharged from the screen elements as they approach the top center, being dropped into a suitable delivery trough 5. 20

In addition to the rotary screen, the apparatus includes an air washing abrasive cleaner or separator 6 and 7 shown in Figures 4 and 7, which separator utilizes as a separating agent in connection with the air draft the difference in the momentum between the dust particles, the foundry and core sand particles and the granular abrasive.

To this end the screened material from the roany suitable source is delivered to a hopper 10, from which it is discharged through the hopper openings 11 on to an inclined plate 12, down which the materials slide and roll, the angle of the plate relative to the horizontal being greater than the angle of repose of the material being treated. In passing down the plate the various particles attain a considerable velocity and upon leaving the lower edge of the plate at 14, they describe a curve of a parabolic nature, the coarser heavier grains of granular abrasive 8 describing the wider curve while the dust 9 falls almost vertically. In order to take advantage of this natural stratification or separation at the edge of the inclined plate 12, the air current is applied in a direction which tends to still further separate the fine particles of dust from the granular abrasive, that is, the air current moves in the direction of the arrow 15, Figure 4, whereby it comes first in contact with the abrasive particles 8, then with the foundry sand or other medium sized particles 107 and finally with the dust 9 which is carried with the air to the dust arresters, the granular abrasive being delivered at 17 to the top of the pressure tank or to any suitable receptacle. The apparatus, beginning with the screen, will now be more specifically described.

The screen structure in the preferred form shown consists of two annular plates 18 and 19, respectively, of substantially equal inside and outside diameters. These plates are spaced apart, parallel to each other and concentric with the same axis, the plate 18 being supported by a spider 20 consisting of a series of arms radiating from a hub 21, secured to the driving shaft 22 mounted in bearings 24 and driven from any suitable source by a pulley 25 secured to the shaft.

The annular plates 18, 19 are, in accordance with the preferred construction shown, 0011-: nected by radial plates 26 a little narrower than the width of the annular plates and secured to the respective annular plates 18 and 19 along their respective end edges 23. These radial plates 26 are shown as spaced along the circumferential length of said annular plates being separated by arcs of about 30 degrees though the exact spacing is not essential. Between the outer ends of the radial plates 26 the annular plates 18 and 19 are spaced or connected by flat plates 27 likewise secured attheir end edges to the flat surfaces of plates 11 and 19, and shown as located substantially on the chords of the arcs separating the outer edges of the plates 26. The outer adjacent edges of the plates 26, 27 are spaced slightly apart at 28 substantially as shown and for a purpose to be further described. Each of the radial plates 26 terminates at its inner edge at 29 in the center of a channel like plate, shape or channel iron 30, which, like the plates 26, 27, extends from one of the annular plates 18 to the other, the

, flanges of the channels 30 at 31 being turned outwardly toward theouter peripheries of the plates 18, 19 so that each said channel 30 forms a double pocket extending along the entire inner edge of the corresponding radial plate 26 providing a pocket on each side of each plate at its inner edge. The annular plates18, 19 are further connected or they may be said to serve as supports for the corner bars 32, extending from one said plate to theother and spaced slightly, i. e., about one to two inches inwardly from the adjacent edge portions of the radial plates 26 and the chord plates 27, i. e. the outer edges of the plates 26 and the adjacent edges of the plates 27, as indicated by reference character 28.

The screen 1, as already suggested, consists of a series of screen elements or pockets 4. The screens or screen walls 34, 35, 36 may be secured at two edges or otherwise connected at two edges tov the annular plates 18, 19, and each of the screens 34, 36 is secured at its inner edge to the corresponding flange 31 of the corresponding channel plate or iron 30, and at its opposite or outer edge it is secured to or supported on the corresponding rod orfillet 32 already described, which forms the corner of thescreen pocket or element 4, so that the mesh fabric or screen forming each of the screen elements or members 34 may be in one piece or three pieces as is found most convenient and economically desirable.

' In the operation of the screen, the material to be treated is fed by way of the chute 2 into the opening 37 in the center of the annularplates 18, 19. The screen being rotated in righthanded direction as shown in Figure 1, the chute 2 delivers at a point near the beginning of the lower 180 arc. As the screen element 34 in front of the chute rotates downwardly, the material passes over the radial screen .34 toward the outer periphery and the fine material whicl. passes through the screen rolls down the radial plate 26, being discharged through the space 28 between the outer edges of the plates 26, 27, and as the screen continues to rotate, still describing the operation of the same screen member 34, the material which does not pass through the screen 34 to be discharged as described, rolls and slides along the screen 35 which is parallel to the chord plate 27, it being understood that the screens 34, 35, 36 are all spaced by a short distance as an inch or an inch and a half from the adjacent plates 26, 27. The material that passes through this screen 35 is then discharged at the next opening 28 to the right as seen in Figure 4, and as the rotation of the screen member 1 continues toward the top of the bottom are, the material rolls and slides along the screen 36, the screenable material passing through the mesh, giving three screening operations as applied to all of the material delivered to the screen to be treated which does not pass through the first screen 34 or the second screen 35.

As the screen element or member 33 being dis-' cussed moves into theupper are, each pocket or channel 30 being at the bottom of its plate 26, catches whatever fine material may have passed through the screen member 36, without being discharged inward radially into the trough 5. To avoid loss of any of the abrasive which may drop into the trough 5 a portion of the trough bottom may be formed of screen as at 38, Figure 2, and a further trough 39 beneath the screen may be utilized to carry the abrasive back to the rotary screen as illustrated.

If the direction of rotation of the screen be reversed, the position of the troughs 2 and 5 must be changed correspondingly.

The material from the screen 1 or from any suitable source is fed to the hopper 10 whence it plate 12 and atits lower end at 41 is curved or deflected toward the lower end '14 of .the inclined plate 12, leaving a reduced opening at 43 for the projection from the lower end 14 ;of the plate 12 of the materials being air washed and separated.

The plate 40 with its curved portion 41 directs the flow of the air which is drawn downward through the top opening 44 in the casing 45 into contact with the material which is falling from edge 14 of plate 12. This draft is maintained by the suction in the ventilating pipe 46, which may lead to any suitable dust collecting apparatus, the desired suction or vacuum being created by means of a fan or other suitable apparatus not shown. Below the plate 40 and spaced therefrom in a .direction transverse to the air current is a baiiie 47 shown as curved in a general way parallel to the curvature of the lower end 43 of the plate 40 and pivotally mounted at 48 at its upper end to swing toward and from the curved portion 41 of the plate 40. The arrangement of the curved portion 41 of the plate 40, and the curved plate 47 spaced apart as shown forms an air passage or nozzle 49 with converging walls whereby the air which enters at the top opening 44 of casing 45 is contracted and discharged into contact with and through the stream of abrasive at 43, which is dropped from the lower end 14 of the inclined plate" 12. The plate 4'7 is adjusted about'its pivot 48 by a thrust rod 149 pivotally connected to the bottom of the plate at 150 and extending through the casing 45 at 151. At this point the thrust rod 149 is engaged by a nut 152 in a pocket 153, the rod 149 being threaded for this purpose. The used abrasive is Stratified as already described, the dust tending to fall directly downward from the edge 14, and the larger and heavier particles being projected outwardly, i. e. to the right in Figure '7, so that the air draft first contacts the larger particles, the direction of which it changes very little, merely having a final cleansing effect on these particles. It then comes in contact with the. finer particles of dust which are. carried to the left in Figure '7 in the direction of the air blast or current indicated by the arrows 51. The air current moves downwardly to the left, as indicated in Figure '7, carrying the dust particles toward the ventilating pipe 46 which as shown extends upwardly toward the dust collectors or separators or other suitable point of discharge for the dust laden atmosphere. The coarser grains of'material, as foundry sand'or the like are deposited on a plate 52 which forms the bottom'wall of the air passage 53 which conducts the air current, indicated by arrows 51 already described, the dust and lighter materials being carried with the current to and through the ventilating pipe 46. This plate 52 is provided with a trap door or trap 54 leading downwardly into a sand hopper 55, which hopper and trap door are utilized only when it is desired to reclaim the sand for further use. .This hopper 55 has a trickle valve 56 at the bottom shown in the form of a flap pivoted at the top so that it remains normally closed, the weight of the accumulated sand causing it to discharge into an external receptacle.

The passage 53 curves sharply upward at 59 into alignment with the ventilating passage 46, and at the bottom of the elbow there is provided an air inlet opening 60 which is preceded in the direction of flow by the overhanging ledge 61. An air current is set up in said passage, 60, due to the vacuum or suction in pipe 46 causing air to be drawn in at 60. This serves to pick up the sand grains and other heavy waste not previously discharged as these materials fall off of the ledge 61, carrying them into the air stream and hence into the ventilating pipe 46. This provision is important only when the trap 54 leading to the hopper 55 for retaining the coarse sand and other heavy waste material is closed permitting the sand to pass along the plate 52 to the ventilating pipe 46.

falling stratified abrasive into a reconcentrated stream, efiecting a more complete mixture of this material, 1. e., preventing the separation of the abrasive into large and small particles. The cleaned abrasive 17 drops from the bafiie 65 to the bottom of the casing 45, which may be the top of an abrasive pressure tank. To prevent accumulation of abrasive above the lower edge of plate 65 a discharge opening is provided, the same having a flap 1'71 to be opened by the weight of the abrasive.

The apparatus as shown further includes an air inlet valve at 66 preferably extending across the entire width of the casing 45. This air opening is for the purpose of reducing the amount of air drawn in at 43 and consequently the velocity of the air current indicated at 15 and 51, which passes through the stream of mixed abrasive, sand and dust at 43 discharged from the lower edge 14 of the inclined plate 12, also referred to herein as a chute. There is a suitable sliding gate 67 for regulating the opening and the amount of air introduced. A

The size of the openings 11 which discharge the material from the hopper 10 is controlled by a sliding plate 13 held in different positions of ad justment by a pin '73 adapted to be seated in any one of a series of holes '75 in the frame of the machine. In both machinesthe material to be treated is fed to the air cleaning apparatus from hopper 10. The alternative form of apparatus shown in Figure 4 differs but slightly from that just described.

In this form of the invention, there is an air passage or exhaust funnel '77 closed on the top, bottom and sides. This is of the same width as the inclined plate 12. In this form of the invention instead of the sand trap gate 54 and the hopper 55, there is a sand trap gate '78 pivoted at its lower edge at '79, and resting at its upper edge against the bottom wall of the passage '77. This gate '78 closes the entrance 81 to a sand hopper 82, having a trickle release valve 182 as in the previous instance. The gate '78 is at the ,will of the operator swung upwardly away from the bottom of the exhaust funnel to admit the sand which it may be desired to reclaim and which rolls and slides along the bottom of the funnel '77. The gate '78 is operated by a tension bar 83 by means of which the gate is pulled upwardly to open it, the position of the bar and gate being adjusted by means of a nut 84 engaging a thread on the bar and resting on the top of the exhaust funnel 7'7. When the gate is closed, all the sand and dirt, follow the dust, sliding and rolling over the top of the gate into the ventilating pipe 85, through which it is carried by the air current created by an exhaust fan or the like.

In this form of the invention, instead of the valve or air opening 66, there is an automatic air inlet valve 86, pivoted at 8'7 to swing upwardly to closed position and downwardly in opening. This valve is providedwith a downwardly disposed lever arm 88 substantially at right angles to the plane of the valve, which arm carries an adjustable weight 89 which tends to close the valve by gravity. This weight 89 may be moved up and down the arm and secured by means of a set screw 90. When the air is drawn through the passage "7'7, the vacuum created due to the suction in the ventilating pipe 85, tends to open the valve admitting additional air in varying amounts corresponding to the resistance offered by the weight, which, in turn, is dependent upon the lever arm of the weight which varies as the position of the weight is changed.

The purpose of this construction is to provide an automatic regulator to maintain a constant or predetermined volume and velocity of air drawn through the abrasive stream or rather the stream of mixed abrasive and refuse from which the abrasive is to be separated. This regulation of the air volume and velocity compensates automatically for irregularities in the suction system.

' maintaining a constant or predetermined volume and velocity of air both at the inlet of the funnel at 91 and through the ventilating pipe 85.

In this connection it is of importance to note that the air thus admitted to the exhaust funnel through the valve 86, as well as that drawn directly through the entrance 91 and through the abrasive stream is taken from the inside of the separator housing and is consequently drawn through the screen 1, providing a more constant draft of air at this point and a more perfect suppression of dust, the dust which would otherwise be released in the screening operation being thus carried through the ventilating pipe 85 and hence to the dust arrester or similar apparatus.

It is of further interest to note that in both types of air washing apparatus, the baflles 40, 41 and 47 direct the air upwardly and release it immediately adjacent the lower edge 42 of the inclined plate 14, from which the materials to be separated are discharged, causing the air to expand upwardly against the edge of the plate concentrating the draft along the discharge edge 42 of the chute or plate 14 and giving the maximum effect in the way of air cleaning or separation of the dust and sand from the metal abrasive.

In the operation of the machine, the material, i. e., used abrasive, mixed with the various dbris from the sand blasting operation, is fed by way of the chute 2 to the rotary screen 1, having inwardly converging screen pockets 4 arranged around its circumference, the screen pockets being enclosed by radial plates 26 and chord plates 27 spaced outwardly-from the screen or foraminous walls, 34, 35, 36, by a distance of one to two inches. 4

As the screen rotates, the material to be screened, delivered to any particular pocket 33 of the series of pockets 4, passes along the screen surfaces 34, 35, 36 in turn, the material which passes through the screens being discharged at the circumferential openings 28. The larger dbris, as nails, wire, chips, etc. is retained by the screens 34, 35, 36and deposited in the discharge chute 5 which leads outwardly and downwardly from the center opening'37 as the screen pockets or sections 4 approach the top center. The passage of the nails and wirethrough the screen is prevented by the plates 26, 27, and at the corners their escape through the openings 28 is prevented bythe members 32 which close the'corresponding areas at the comers in addition to supporting the screen.

The material discharged at the circumferential openings 28 through the bottom 180 arc of rotation of said section 4 is dropped into the hopper- 10, the larger dbris, i. e., the wire, nails and chips being discharged by way of chute 5, see particularly Figure 4, as each pocket approaches the top center. From the hopper 10 which extends across the machine, the material is fed to the air cleaner or air washer indicated by reference character 6 in Figure 4 and by reference character 7 in Figure 7. From the hopper 10 the material passes through a series or holes 11 arranged across the machine ar. slides down the inclined plate 12, being projected from the lower edge of the plate at 14. As thus projected at an angle to the vertical, the different classes of particles tend to separate or stratify the line particles of material referred to as dust, indicated at 9 in Figures 4, 8 and 9, tending to fall almost straight down while the heavier particles 106 of abrasive tend to follow the line of the chute or plate 12, being projected outwardly and downwardly on a parabolic curve. The sand and particles of intermediate sizes and weights, tend to take an intermediate course.

In accordance with the invention, the particles resistance to which they are subjected when thus,

projected from the edge of the plate 12. This air current in the form of the invention shown, is due to a partial vacuum created by the suction in the ventilator passages 85, 46, which is maintained by an exhaust'fan or in any suitable manner, it being understood that the passages through the air cleaning apparatus 6. 7 are closed at the sides as indicated in Figure 5.

In the form of the apparatus shown in Figure 4 the air used in treating the abrasive is drawn through the screen 1 tending to dispose of the dust raised in the screening operation, the air current being indicated by the arrows 15, Figures 4 and 9.

The air thus drawn into the apparatus is di rected by the baflie 40 curved at its lower end at 41 toward the lower edge 14 of the chute plate 12 and by a second and lower baffle 47, which bafiles form a converging passage or nozzle at 49, Figure 4, and 49, Figure 7, whereby the air current is contracted'and projected transversely against and through the stream of falling material including the abrasive itself and sand. which comes from the edge 14 of the chute plate 12. This air current tends to separate thedust and sand at 9 from the falling abrasive at 8, moving it away from the abrasive in the direction in which the sand tends to separate from the abrasive by the gravity and momentum-and air resistance stratification already described. The abrasive 8 thus cleaned and separated from all the other materials is dropped directly upon an inclined plate 65,- which reassembles the different sized particles of abrasive depositing them in the form of a heap 17 on the bottom of the easthe abrasive are supported on aplate 52 inclined.

downwardly to the left and forming'the bottom of the passage 53, leading to the ventilating passage 46. The air drawn into this passage is further diluted or the vacuum is reduced by air ad- 5 mitted through a valve opening 86 in the casing 45, the size of said opening being regulated by the shutter 67.

When desired, the sand separated from the other materials and supported on and sliding down plate 52 is dropped into hopper 55 by open-- ing the shutter 54 and the dust is carried into the ventilating passage 46. when it is not desired to reclaim the sand, the sand and dust may be carried into the ventilator 46 by closing the trap 54, the sand being raised by a further draft admitted at 60, beneath and beyond the ledge 61 at the bottom of the incline which leads to the ventilating passage.

The operation of the apparatus for cleaning abrasive by air washing, Figure 4, which is shown combined with the rotary screen 1, difiers from that of Figure 7 in that the separating air used in the air cleaning apparatus 6 is passed through the screen 1 to any suitable type of dust collectors or separator, not shown. This would be located at the end of the ventilating passage. The dilution air admitted at 87 is also passed through the screen 1 and the air dilution or reduction in the vacuum is rendered automatic by the valve 37 controlled by the adjustable weight 89 or any suitable automatic means, thus automatically regulating and making uniform the air I supply and air pressure at the opening 91 and also in the ventilating pipe 85. By taking the cleaning air from the revolving screen 1, the dust raised in the initial screening operationis carried to the ventilator and-to the dust collector without special provision for this purpose.

I have thus described specifically and in detail an apparatus for air screening, separating and reclaiming used abrasive, the description being specific and in detail in order that the manner of constructing, operating and using the same may be clearly understood, however, the specific terms herein are. used descriptively rather than .in a limiting sense, the scope of the invention being defined in the claims.

What I claim as new and desire to secure by Letters Patent is:

1. An apparatus for air cleaning abrasive comprising an inclined chute, means for feeding the abrasive to the top of the chute, permitting it to roll and slide down the chute and to be projected from the lower edge of the chute whereby the finer materials are caused to be dropped from the end of the chute, the heavier materials being projected forwardly, bafiies for concentrating the air and directing'it against said stratified stream, bringing it first in contact with the heavier particles whereby the finer material is blown away from the heavier materials, a passage leading downwardly from the lower edge of said inclined chute toward the bottom of the apparatus, a suction passage connected to and leading upwardly from the lower end of said latter passage, and an air inlet near the bottom of said suction passage, the air admitted at said air inlet serving to raise the solid waste materials into the air current in said suction pipe.

2. An apparatus for air cleaning abrasive comprising an inclined chute, means for feeding the abrasive to the top of the chute, permitting it to roll and slide down the chute and to be projected from the lower edge of the chute whereby the finer materials are caused to be dropped from the end of the chute, the heavier materials being projected forwardly, baiiies for concentrating the air and directing it against said stratified stream, bringing it first in contact with the heavier particles whereby the finer material is blown away from the heavier materials, a passage leading downwardly from the lower edge of said inclined chute toward the bottom of the apparatus, a suction passage connected to and leading upwardly from the lowerrencl of said latter passage, and

an air inlet near the bottom of said suction passage with a ledge extending partially over said air inlet in the direction of flow, the air admitted at said air inlet serving to raise the solid waste materials into the air current in said suction pipe.

3. The combination in an air cleaning apparadraft on said stratified material, passing it through said Stratified material oppositely to said incline, an inclined chute leading the air and finer waste materials suspended therein and some heavier waste materials downwardly from the lower end of said incline and a trap leading from said inclined chute for dropping the heavier materials and separating them from the dust.

4. In an apparatus for air cleaning abrasive, an inclined way for the material to be treated, means for feeding the material at the top of said incline, permitting it to move by gravity down the incline and be projected from the lower edge of said incline tending to form a stratified stream of the material; a baiile overlying said way and substantially parallel thereto and at its lower end curved sharply toward the lower end of the way, a second baiiie spaced from said curve and inclined toward the end of said incline and terminating short of the path of the said stream of material, an inclined passage for the materials separated from the abrasive, beginning at a point below the lower edge of said first incline, and means for creating an air draft between said baffles whereby the air is projected against and through said stream coming in contact first with the heavier particles which are mainly abrasive, separating the lighter particles therefrom and carrying them into said inclined passage, the heavier particles being permitted to drop between the second battle and the inclined passage.

5. In an apparatus for air cleaning abrasive, an inclined way for the material to be treated, an

accumulating hopper for feeding the material at the top of said incline, permitting it to move down the way by gravity and be projected from the lower edge of said way tending to form a' stratified stream of the material, a baflie over-' lying said way and substantially parallel thereto and at its lower end curved sharply toward the way, a second baille spaced from said curve and tending toward the end of said incline and terminating short of the path of the said stream of material, an inclined passage for the waste material separated from the abrasive beginning at a point below the lower edge of said first incline, and means for creating an air draft between said bafiles' whereby the air is projected and a deflecting plate in the path of said heavier particles for reassembling the abrasive particles.

6. The combination in a separating and cleanliminary separating unit comprising a rotary screen having peripherally arranged screening means and a central opening providing for the passage of air, means for feeding the material to the screen near the center and discharging the cleaned material at the periphery, means for discharging the waste, a subsequent cleaning unit having an inclined way for the abrasive to the top of which it is led from the rotary unit, the incline being such as to permit the abrasive to roll and slide down the way, being projected from the lower edge of said incline and thereby stratifled separating the heavy from the light particles, the apparatus being enclosed and having means for drawing air through said screen and downwardly through the apparatus in the direction of the progress of the abrasive means for deflecting the air and passing it through the stratifled materials oppositely to the incline of said way, whereby the dust and other waste are separated from the abrasive and carried out of the apparatus with the air.

7. ,The combination in a separating and cleaning 'apparatus for abrasive and the like, of a rotary screen having peripherally arranged screening means and a central opening providing for the passage of air, means for introducing the material to be cleaned near the center of the screen, means for discharging the abrasive from the screen near its periphery, means for discharging foreign particles whereby they are separated from the abrasive, an inclined chute leading downwardly from the point where the screen discharges the abrasive and adapted to receive the materials discharged therefrom, the chute being inclined to cause the abrasive to roll down the chute, being discharged therefrom in a stratified stream of material, and means for drawing an airdraft through said central opening in the screen and downwardly through the apparatus means for deflecting said air and causing it to pass transversely through said stratified stream of material, separating the lighter particles from the abrasive.

8. The combination in an apparatus for cleaning abrasive of a rotary screen having a central opening, means for leading the material thereto, means for discharging the partially cleaned abrasive therefrom and separate means for discharging the larger debris from the rotary screen, an inclined chute arranged to receive the abrasive from the screen, the chute being inclined at an angle sufficient to cause the abrasive to move down the chute and to be projected from the lower end of the chute whereby the material is stratified, the finer materials tending to fall directly downward, and the heavier materials being projected forwardly, means for drawing an air draft through the central opening in said screen and downwardly through said apparatus, means for deflecting said draft and passing it through said stratifled stream, bringing it first in contact with the materials which are projected forwardly, and then in contact with the materials which tend to drop more nearly in a vertical path, means for concentrating said air current beneath and in contact with the lower edge of said inclined chute, and means for admitting air to said current beyond the lower edge of said chute to regulate the air draft and means for separately delivering the separated material.

9. In an apparatus for air cleaning abrasive, a rotary screen having screen members at the periphery and a central opening for air an inclined way for the material to be treated, means for feeding the material from said screen to said incline permitting it to move down the incline to be projected from the lower edge of said incline tending to form a stratified stream of material, means for drawing a draft of air through said screen and downwardly through said apparatus and converging means terminating immediately adjacent the lower end of said inclined way for concentrating the air draft immediately below said edge, said air draft being directed oppositely to said downward incline and coming in contact first with the heavier particles which are mainly abrasive and later with the lighter particles, separating the lighter particles including the dust and other waste therefrom, and carrying them in a direction opposite to the direction of motion of the abrasive, etc. as it comes down said incline.

ROBERT B. HUYETT.

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