US2513960A - Movable deck pneumatic coal cleaner - Google Patents

Description

July 4, 195o C. v. ORE 2,513,960

MOVABLE DECK PNEUMATIC COAL CLEANER Filed Feb. 13, 1947 2 Sheets-Sheet 1 mama .hay '4, raso MOVABLE DECK PNEUMATIC COAL CLEANER Carl V. Ore, Harvey, Ill., assigner to Roberts and Schaefer Company, Chicago, Ill., a corporation of Illinois Application February 13, 1947, Serial No. 728,224

l 4 Claims.

This invention relates to the separating or classii'ying of heterogeneously intermixed materials consisting of particles of different specific gravities and/or sizes, and is particularly concerned with improvements in a movable deck pneumatic coal cleaner for use primarily with raw coal of relatively small particle size.l

The term coal cleaner is applied to apparatus such, for example, as described in U. S. Patents Nos. 2,245,942 and Re. 21,682. The apparatus disclosed in these patents comprises means forming an inclined trough-like passage provided with a perforated air-pervious deck plate disposed on top of a resistance pack containing marbles or the like, and means for directing air impulses into and through the resistance pack for escape upwardly through the perforations in the deck plate. The raw coal is fed to the deck plate at the elevated end thereof, moving along its inclined surface, and is subjected to the action of the air impulses which eilect stratification of its particles in accordance with their specific gravities. Coal, which is the lightest component of the raw feed, orients itself on top of the material bed and heavier particles, constituting refuse, stratify underneath the coal. The various stratified products are drawn olf for removal to their respective discharge points.

The principal object of the invention is to provide an airflow separator or cleaner of the general class described above for treating raw coal of small particle size varying, for example, from about three-eighths of an inch down to and including nely pulverized and comminuted dustlike particles, and for obtaining clean coal of a high degree of purity such as is required in metallurgical coal and in pulverized coal for numerous industrial operations including the operation of marine and locomotive boilers,A cementburning, central heating plant operation and the like.

This object is realized by the provision of a structure having (1) an elastically suspended longitudinally resiliently Ibalanced trough-like inclined material deck for receiving the raw mate- 'rial, the deck comprising a plurality of longitudinally serially related deck sections, each section including a perforated air-pervious deck plate and a resistance pack, the successive deck sections beingseparated by downwardly directed intermediate discharge passages for the removal from the material stream of successively separated relatively coarse heavy material particles; (2) means forming underneath the material deck 'a plurality of cells, one for each deck section,

and means for injecting into each cell air impulses of controlled magnitude for adjusted upward escape through the associated resistance pack and perforated deck plate into the raw material thereon to impart controlled fluid mobility and buoyancy to such material; (3) means for reciprocating, vibrating or oscillating the material deck with all its deck sections at a relatively high frequency and relatively small amplitude for the two-fold purpose of imparting mechanical mobility to the material flowing over the various deck sections and to cause iinely divided particles of intermediate specic gravities to move for discharge continuously downwardly through the deck plate and through the underlying resistance pack of each deck section in counter-current to the air impulses injected into the corresponding deck section; and (4) means common to all deck sections for receiving and removing the small particles of intermediate gravities which are continuously discharged therefrom in countercurrent to the air impulses injected thereinto.

Details of the various objects and features, including those mentioned above, will appear from the description of the accompanying drawings, in which Fig. 1 shows a more or less diagrammatic elevational side view of an embodiment of an airiiow separator or cleaner made in accordance with the invention, with parts broken away to show interior structures;

Fig. 2 is a section, on an enlarged scale, through the new separator taken approximately along lines 2 2 of Fig. 1; and

Fig. 3 illustrates, on an enlarged scale, -the means for longitudinally resiliently balancing the material deck, as seen when looking in the direction of the arrows along lines 3--3 of Fig. 1.

Like parts are numbered alike throughout the drawings. Known details and elements will be referred to only to the extent required for conveying an understanding of the structure and operation of the invention.

Referring now to the drawings, the new separator comprises a framework including suitably positioned structural upright members ll, l2 and I3, I4 disposed on either side of the machine substantially at the opposite ends thereof. The uprights I 2 and I3 on either side are joined by suitable sheet members forming the side Walls 14 and l5 which extend throughout the lower part of the machine. Vertically extending sheet members join the uprights I3, I4 on either side in the rear and similar sheet members extend forwardly from the uprights H to the left as seen in Fig. 1. The forward end of the machine may be closed by a suitable plate or the like. Secured to the top of the uprights I2 and I3 on'either side and extending therebetween in longitudinal direction are the generally U-shaped girders I5 and I6, respectively, (see also Fig. 2). Secured to the girders I5 and I6 are downwardly extending and outwardly aring shields |50, and IBa, respectively.

Each girder I5 and I6 carries a number oi longitudinally spaced brackets su-ch as I1, I8, I9, and suitably attached to each of these brackets is a downwardly depending resilient member, e. g., a composite or laminated leaf spring. The leaf springs secured to and depending from the brackets I I8, I 9 on the girder I5 are marked 20, 2I, 22, respectively. The top girder I6 extending on the other side, in back of the girder I E, as seen in Fig. 1, carries in a similar manner brackets corresponding to I7, I8 and I9, one such bracket being indicated in Fig. 2 at 23, and leaf springs corresponding to the springs .22, 2l and 22 are secured to such brackets, the leaf spring corresponding to spring 2| being indicated in Fig. 2 by numeral 26. There are thus three pairs of leaf springs 2t, 2I24 and 22, which extend downwardly from the top girders I5 and I5.

The lower ends of the three pairs of leaf springs are secured to brackets which project laterally outwardly from longitudinally extending, generally U-shaped structural members 25 and 26 disposed slightly above and vertically spaced from the side walls i4 and 15, respectively. The4 structure is apparent from Fig. 2, showing the lower ends of the pairs of leaf springs 2l and 24 associated with the brackets 2l--2B, respectively, which extend laterally outwardly from the members 25-20. The lower ends of the pairs of leaf springs and 22 are secured similarly to brackets extending laterally from the members and 25. The longitudinally extending structural members 25 and 26 are thus elastically suspended from the longitudinally extending top girders I5 and I6 of the machine and are transversely spaced as is particularly apparent from Fig. 2. These members form part of the material deck and carry the serially related deck sections. Upwardly extending and outwardly flaring shields 25a and 26a are secured to the structural members 25 and 26, respectively, forming with the deck sections a longitudinally extending trough-like structure which is inclined at an angle of about 8 to 15 degrees.

At the rear end of the material deck is disposed a generally U-shaped structural member 29 which extends transversely across the rear ends of the longitudinally extending resiliently suspended deck members 25 and 26. From the member 20 extends in rearward direction a connecting member, e. g., an I-beam 30. This connecting member is associated with suitable means for imparting vibrations thereto which are transmitted to the material deck, including all the deck sections disposed between the structural members 2'5 and 2S, for example, with a vibrator 3 I. This vibrator may be of the rotary type known as ,Eureka Buhler Drive, manufactured by S. Howes Co., Inc., Silver` Creek, N. Y., comprising two disk-like masses whose axes of rotation are radially oiset such as illustrated by the Shaler Patents 1,999,213 and 2,059,784. These masses are rotated in common and produce thrusts which affect the connecting beam 30, thereby vibrating, reciprocating or oscillating the material deck. The vibrator is operated through the medium of a belt drive,

from a motor 32 mounted on a shelf 33 secured between the rearmost pair of upright members I4. Other suitable means for reciprocating, vibrating or oscillating the material deck may, of course, be used.

The frequency of the vibrations or oscillations imparted to the deck may be from about 800 to 1400 per minute; the amplitude may be approximately lg", that is, 115 in either direction from the normal position of the material deck. It will be seen, therefore, that the amplitude of the vibrations is relatively small, while the frequency is relatively high.

The suspended inclined material deck with its various deck sections is rather heavy, and the structure would normally tend to position itself by gravity in a forward direction; that is to say, it would tend to sag toward the left as seen in Fig. 1. Vibrations applied directly to the freely suspended structure would be distorted by the inertia of the masses in the presence of such sagging, In order to counteract the sagging and to control the vibrations, I have provided means for resiliently balancing the structure in longitudinal direction. This balancing means is indicated in dotted lines at the rear end of the machine, as seen in Fig. 1, and is there generally indicated bythe numeral 35. It is shown on a larger scale in Fig. 3.

The balancing structure comprises a pair of transversely extending supports 36 and 3l which are attached to the pairs of uprights I3 and I4 in the front and in the back of the machine, respectively. Mounted on the members 36-3i and connecting such members is a shaft 38. It will be noted that the ends of the shaft are secured in bushings 39 and 40, by means of pairs of nuts 4I, d2 and 43, 44, respectively, and that the shaft can therefore be positioned with respect to the transverse members 35, 3i as may be desired. The shaft carries a floating bushing associated with a bracket member 46 which extends upwardly as shown in Fig; l and is secured to the connecting I-beam 32 projecting rearwardly. from the transverse member 20 at the rear end of the suspended deck and carrying the vibrator or oscillator 3l. Also secured on the shaft 38 of the balancing structure are a pair of flanged bushings 4l and 48, respectively, and between these bushings and the member le are disposed springs 49 and 50. The spring l@ extends between the bushing 4l and member 46, and the spring 50 extends between the bushing 48 and member 46. The position of the bushings Il and 83 on the shaft 33 may be adjusted as desired, by the nuts 5i and 52, for the purpose of adjusting the tension or pressure of the springs 49, against the member t5.

The structure thus permits adjustment of the spring pressure against the member d6 (which is connected with the connecting beam 30 projecting rearwardly from the elastically suspended material deck and carrying the vibrator 3i) and also permits resilient adjustment of the position of the member 46 relative to the supports 36-3L and therewith adjustment of the connecting beam S0 and the material deck in a desired normal position. The operation of the vibrator ti vibrates the material deck, and the vibrations are controlled by the springs 45, 50 pressing against the member 46 carried on the floating bushing t5.

The adjustment counteracts the forward sagging of the material deck, which would other- Wise take place due to the incline at which it is disposed... The vibrations or oscillations imparted by the vibrator 3| to the connecting beam Il and thence to the forwardly extending material deck are damped and cushioned. Forces set up during the vibration, due to inertia, are eectively counteracted. 'I'he amplitude of the vibrations, as noted before, may be 11u" to either side of a median center line which may be drawn through the member 46, as shown in Fig. 3, after completing the adjustment. 'I'he amplitude is, of course, not a fixed quantity and may be chosen as desired, being given as an example.

There are four deck sections provided in the structure shown in the drawings. The rearmost or first deck section is indicated in Fig. 1 by the numeral 60. This deck section terminates at its forward end in a downwardly extending intermediate discharge passage indicated in Fig. 1 by the numeral 6|, which separates it from the second deck section 62. A similar downwardly extending intermediate discharge passage 63 separates the forward end of the deck section 62 from the rear end of the third deck section, the forward end of which terminates in the downwardly extending similar discharge passage l64. 'I'he fourth or last deck section terminates iin the discharge passage 65 near the forward end of the machine. Numeral 66 indicates the discharge for the clean coal.

A weir such as 80 is shown in Fig. 1 associated with the rear end of the deck sectio'n 62. This w eir is a transversely extending plate which is vertically adjustable so as to provide a banking effect with respect to the raw material stream owing from the deck section 60 over and onto the deck section 62. Similar weirs may be associated with each of the discharge passages 63. 64 and 65.

Each deck section comprises a perforated airpervious deck plate on top of a resistance bed containing suitable members, for example, clay members or glass marbles of a desired size, say 1/4" to 11e" in diameter. The structure of the deck sections, including the associated perforated deck plates and marble packs. will be apparent from consulting the previously mentioned Patents 2,245,942 and Re. 21,682.

The perforated deck plates may be made of suitable material, e. g., brass, but are preferably made of stainless steel. The size of the holes in the deck plates is chosen so as to provide for a maximum open area of about 22% to about 30%. For example, there may be 108 holes per square inch, each hole of a diameter of .05" resulting in an open area of 23%, or 400 holesv per square inch, each hole of a diameter of .027" also resulting in an open area of 23%; or there may be 225 holes per square inch, each hole of a diameter of .04" resulting in an open area of 28%.

Underneath each deck section are disposed transversely extending valve slides such as 61-68 (shown in Fig. 1 in connection with the first deck section 60) which are movably mounted between guide members such as 69. Each valve slide is provided with openings coacting with openings in the bottom plate of the associated deck section and is movable or slidable transversely by a suitable means, for example, an adjusting screw, extending to the outside. The arrangement is apparent from Fig. 2, showing part of the deck section 62. Underneath the bottom plate 55 is indicated the valve slide 56 which is operable by means of an outwardly projecting screw 51. Each deck section is provided with such valve slides for the purpose of regulating the air supply into and through its marble pack for escape through 75 the perforations in its associated deck plate.

Further details of the structure and operation of the valve slides may be had from Patent No. 2,374,865.

Each downwardly extending intermediate discharge passage 6|, 63, 64 and 65 separating the various deck sections terminates in a discharge mechanism comprising a transversely extending casing such as 13 containing an arcuate tray 10 and an oscillating/scraper 1| as well as a rotatable transversely disposed screw 12. The casing containing these discharge elements extends transversely within the lower part of the machine underneath the associated intermediate discharge passage, thatA is, within the space dened .by the side walls 14 and 16 (see also Fig. 2). wardly extending passage directed into the discharge mechanism are connected with the associated casing, such as 13, by suitable transversely extending flexible bellows-like sealing members, as indicated in Fig. 1, so as to. prevent the escape of air into the discharge mechanism. They discharge casing 13a shown in Fig. 2 correponds to the casing 13 of Fig. l, and contains the discharge mechanism for the intermediate discharg`e passage 63 including the screw 12a which .corresponds to screw 12 indicated in Fig. 1. The transverse bellows-like seal |13 extends from the casing 13a and connects with the plate forming part of the discharge passage 63 to prevent the escape of air into the casing 13a.

flach discharge mechanism is associated with an end plate at the front and a similar end plate in the back, and these plates are mounted on the side walls 14'and 15, respectively. The end plates I2 and 82a are thus associated with the discharge mechanism for the intermediate discharge passage 63 (see Figs. 1 and 2); the front end'plate 8| coacts with a similar end plate on the side wall 15'of the machine in connection with the intermediate discharge 64; and similar front and back end plates are provided for the discharge mechanism associated with the intermediate discharge passage 6|. These end plates carrycertain operating parts.

The discharge mechanisms are actuated from an eccenter 85 operated by a motor associated with a suitable speed reducer generally indicated in Fig. 1 at 86. An arm 81 extends from the eccenter 85 into pivotal engagement with a connecting member 88 which in turn is pivotally connected by means of a rod 89 with a connecting member 90, the latter being connectedby a rod 9| with a connecting member 92lto which is pivoted the rod s3, and the forward end of the latter is pivotally mounted on the arm 94. When the eccenter 85 is actuated, it reciprocates the connecting rod 81 and therewith the gang of connecting rods 89, 9| and'93, oscillating in this 7 to oscillate the scraper such as 1| for the purpose of feeding material to the discharge screw such as 12. The arm |08 is similarly keyed to the shaft ||0 (Fig. 2) to oscillate the scraper associated with the discharge mechanism for the intermediate discharge 63 so as to feed separated ma- The transverse plates forming the down-` terial onto the screw 12a. The connecting rods |02, |03, |04 and |05 are adjustable on their asscciated oscillating arms 94, 95, 96 and 91, respectively, so as to adjust the stroke of the respective oscillating scrapers actuated by these rods.

The discharge screws move the discharged material laterally at the bottom of the associated casings for discharge into downwardly directed chutes. Thus the discharge screw l2 within the casing '|3 moves the material received from the intermediate discharge 6I into the chute IIB; the screw 12a (Fig. 2) within the casing `|3a moves the material received from the discharge 63 into the chute I6; and chute I I1 receives in a similar manner the material from the intermediate discharge passage 64.- The discharge mechanism associated with the discharge passage B5 at the forward end of the machine discharges directly into the chute I I8.

The discharge screws associated with the various discharge mechanisms are operated by suitable drives, e. g., by chain and sprocket drives such as indicated in Fig. 2 at |20. f

Further details of the discharge mechanisms and their operation may be had from Patent No. 2,334,337.

At the bottom of the machine defined by a suitable bottom plate I2I (Fig. 2) are disposed three rotatably mounted pairs of screws, each pair being carried on a common shaft. The three shafts are indicated in Fig. 2 by the numerals |22, |23 and |24. The pair of screws associated with the shaft |24 are indicated by numerals |28 and |29.

\ left feed, respectively, to transport material accumulating at the bottom ofthe machine inwardly from its extreme ends toward the middle for discharge into the chute |30. In this chute is disposed an air seal comprising a star wheel I3! to prevent escape of air thereinto. The star wheel is operated by a suitable drive, for example, a chain and sprocket drive |32, indicated in Fig. 2.

Extending downwardly from each of the casings containing the discharge mechanisms associated with the intermediate discharge passages 0 63 and St, and secured to the respective casing, is a valve plate such as indicated at M0 in connection with the casing 'i3 (Fig. 1) provided for the discharge mechanism which receives material from the passage 6|, or valve plate iii! (Fig. 2) associated with the discharge casing l3a which receives material from the passage 63. The valve plate extends in each case transversely across cated at |02, M3, Mit, respectively, these valve i Each valve plate is provided with valve plate at |45 and Hit, which project downwardly into the spaces between the screws carried on the shafts I 22|23 and |28| 24, respectively. Each of the extensions |45, |46 is likewise provided with an opening or openings, and the valve slide |44 carries extensions corresponding to the extensions |45, |46. Similar valve means carrying a valve plate and associated valve slides is also connected with the discharge casing which receives material from the intermediatedischarge passage 64.

The chamber extending between side walls 'I6-l5 underneath the various deck sections is in this manner divided into cells, one for each deck section, and each cell is provided with means for regulating the air supply that is to be admitted into it for use in its associated deck section.

The air supply may be from any suitable source by way of the duct |50 (Fig. 1) which is provided with a flutter valve |52 operating between shields |62, |63. The air pressure is relatively low and may vary from about 1.25 WG to about 2.00 WG. The utter valve |52 is rotated at desired R. P. M. by a suitable drive, for example, by a chain and sprocket drive, from the motor and speed reducer 06. Air impulses of relatively low pressure are thus suppliedinto the space or cell below the deck section 60, and the amount of air which is admitted into this deck section is regulated by the valves such as 68 and 61 disposed directly underneath its resistance pack.

The admission of air into the second cell underneath the second deck section 62 is regulated by the valves associated with the valve plate |40 depending from the casing 13. The air which is admitted for use in the deck section 62 is regulated by the valve slides underneath its resistance pack.

Air is similarly admitted into the third and fourth cells underneath the corresponding deck sections by way of the valve plates I4| depending from the casing 13a (Fig. 2) and from the casing associated with the discharge passage 64, respectively.

Vertically extending valve openings may be provided in the partition valve plates such as |40, |4| instead of the rows of openings described, for valve coaction with similarly formed valve slides or sliding plates.

The raw material is supplied through a hopper |65 (Fig. 1) and drops onto an inclined surface formed by the transversely extending plate I6I.y This plate deflnes the bottom of a feed chamber in which is disposed an oscillating feed mechanism operable by the oscillating arm |61. feed mechanism may be similar to the discharge feed mechanisms used in connection with the various discharge passages tl, S3 and 64, and details of it may be had by consulting Patent No. 2,334,337. Shields such as |68 extend on either side forwardly from the feed chamber to guide the raw material into the trough of the vibrating material deck.

The oscillating or vibrating deck comprising the various deck sections as described is connected with the lower part of the machine by means of ilexible bellows-like sealing members |'|I, |12, the bellows il! connecting the deck with the side wall M and the bellows |112 connecting with the side wall l5. Transverse bellows members of similar structure are provided at the forward and at the rear ends of the oscillating deck. The deck with its various deck sections is thus sealed against the escape of air except through the perorated deck plates and is movable on its suspension springs in response to the actuation of the vibrator.

The sxTids wit-:sa and Isam extending from the top girders I and I6 vand from the suspended deck members and 25, respectively, may be connected by a suitable material such as canvas members so as to seal and close the top part of the machine, above the vibrating deck. to the outside.

A dust hood |80, shown in Fig. 1, extends upwardly from the machine and terminates in a suitable exhaust duct for drawing dustvladen air of! for cleaning and recirculation back to the intake |50.

The-operation of the machine may now be brieiiy summarized as follows:

The raw coal is supplied to the hopper |65. The operation is started by switching on the motor 86 provided with a speed reducer, thus rotating'the eccenterf85 and thereby oscillating the arms ill-51 which eifect the oscillation of the discharge Scrapers such as 1| of thedischarge .mechanisms associated with the various intermediate discharge passages 6|, 63, 64 and 65. The arm |61 is at the same time oscillated for the purpose of actuating the mechanism for` feeding the raw material onto the first deck section 60. Air under pressure is supplied to the duct |50, and the flutter valve |52 is rotated at a predetermined R. P. M. to admit air to the machine in the form of impulses. The operation of the vibrator 3| is started by switching on the motor 32. The discharge screws associated with the various intermediate discharges are actuated l of the raw material are thus discharged through by the corresponding chain and sprocket drives such as |20 in Fig. 2'.

The air admitted into the cell underneath the first deck section 60 flows upwardly through the resistance pack of this section and through the perforated deck plate in accordance with the setting of the slide valves such as 60 and 61. The amount of air to be admitted to the second deck section 62 is regulated yby suitably adjusting the slide valves associated with the valve plate depending from the discharge casing `13. The air admitted to the third and fourth deck sections is likewise adjusted by the slide valves associated with the discharge casings in back of the mounting plates 82 and 8|, respectively. Each of the deck sections is provided with slide valves such as 68 and 61 for further regulating the air supply directed through the corresponding resistance pack for` upward escape through the associated perforated deck plate in accordance with the needs of the material bed flowing over each `deck section. I

The raw material flows onto the rst deck section and is subjected to the actin of the air impulses as well as to the action of the vibrations effected by the vibrator 3|. The magnitude of the air impulses is adjusted to the needs of the raw material bed forming on this deck section. The material immediately orients itself in stratified layers as it flows along the first deck section, and upon arriving at the rst takeoff or intermediate discharge passage 6|, the heaviest and largest componentsA are positioned at the bottom of the material bed and drop down onto the discharge tray 10 from which they are scraped by the scraper 1| onto the screw 12 which feeds the discharged particles into the chute or duct ||5. The Weir 00 and similar weirs associated with the successive intermediate discharge passages 63, 64, are adjusted to desirable heights so as to provide proper banking oi' the material stream at the corresponding discharge points. The heaviest and largest components the passage 6| and removed through the chute ||5.

The remaining material continues to flow onto and along the second deck section 62 on which it is subjected, in the presence of vibrations, to air impulses of a magnitude adjusted to its needs, and the heaviest and largest components of the material, which'stratify under the action of such impulses and vibration at the bottom. drop downwardly into and through the intermediate discharge passage 63 for removal into chute ||6 by mea-ns of the discharge mechanism contained in the discharge` casing 13a (Fig. 2) which is identical with the mechanism associated with the discharge passage 6|, as shown in full lines in Fig. 1.

The material remaining after removal of heavy and relatively large particles at the intermediate discharges 6| and 63, as described, continues to now along the third and finally over and along the fourth deck section, at the end of each of which the heaviest and largest components are discharged through the associated intermediate discharge passages 64 and 65, respectively, for removal through the ducts or chutes ||1 and i8, respectively.

The clean coal flows over the inclined end section 66 of the vibrating deck for discharge through the chute |10.

Finely divided matter contained in the material as it flows along the various deck sections, consisting of particles of intermediate gravities and of maximum sizes corresponding approximately to the size of the openings in the various deck plates, works continuously and progressively downwardly through such openings and through the corresponding resistance packs, in countercurrent to the upwardly directed air impulses, leaving the resistance packs through the bottom openings associated with the valve slides underneath each deck section. These particles drop downwardly to the bottom of the machine where they accumulate along the bottom plate |2| At a certain point of the operation the screws on the shafts |22, |23 and |24 on top of the bottom plate |2| are started by their respective drives such as |21, and the star wheel |3| is rotated by means of the chain and sprocket drive |32. The fine material of intermediate gravities that has accumulated will accordingly be moved from either end of the machine toward the middle and will drop onto the star wheel |3| which discharges the material in a controlled manner downwardly into the chute |30, and at the same time acts as an air vseal to prevent the escape of air. The maximum size of the particles thus discharged is determined by choosing holes or .corresponding size to be provided in the various deck plates.

The progressive and continuous discharge of the finely divided particles of intermediate gravities throughout the extent of each deck section, in counter-current to the air impulses, as described in the foregoing paragraph, is considered an -important feature4 of the present invention. As intimated initially, thisl feature effects automatic cleaning of the resistance packs, permits more eicient utilization of the air' at reduced pressures, accelerates stratification, thereby increasing the ton/hour capacity of the separator at reduced energy input, and thus permits the efficient treatment of raw coal of relatively small particle size without recourse to hydraulic separation, delivering clean coal of a high degree of purity.

'I'he separated products, which are discharged passages 6I, 62 and 63 into the chutes I I5, I I6 and H1, respectively, consist predominantly of heavy particles constituting refuse. The nes, which are discharged from all of the deck sections in counter-now to the air impulses dropping to the bottom of the machine for removal into the chute 130, have likewise been found to consist predominantly of heavy particles constituting refuse. The material entering the intermediate discharge passage 65 at the forward end of the fourth deck section for removal through the chute i I8 will, however, usually contain valuable particles which are recovered by screening, the underflow being predominantly refuse and the overflow from the screen being either predominantly coal, which is mixed with the coal drawn off at the inclined forward end 66 of the deck, ora true middlings product which may be recirculated. It is understood, of course, that conditions may vary and, if it is found that one or the other intermediate product contains valuable material, such product may be screened and/or re-circulated as desired or necessary, to recover its valuable constituents.

The new apparatus and process has been described in connection with the separation or cleaning of coal for which it has been designed. Some or all of the new features may be used in related or different fields, including the beneciation of minerals and ores.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected bv Letters Patent of the United States.

I claim:

1. In apparatus for separating raw co'al of relatively small particle size having a longitudinally extending air-pervious material-receiving deck disposed above a resistance pack which forms an operating unit therewith and having means for feeding ra-w coal onto said deck at one end which forms the feed end thereof, relatively stationary supports disposed above said operating unit, resilient hanger means secured to and downwardly depending from said supports for suspending said operating unit at an incline with the feed end disposed at a higher level than the opposite end which forms the coal discharge end thereof, said incline being at an angle at which gravitational force will normally tend to move said operating unit causing sagging thereof forwardly awayv from said means for feeding raw coal onto the feed end thereof, means forming an arm disposed at the feed end of said operating unit and longitudinally rearwardly extending therefrom underneath said means for feeding raw coal thereto, an unbalanced Weight vibrator solely supported on said arm ai; the free end thereof, balancing means coacting with said arm for longitudinally resiliently balancing said inclined operating unit in predetermined longitudinally adjusted position to counteract said gravitational force and to position the feed end thereof in predetermined normal position relative to said raw coal feeding means, said balancing means comprising a pair of spaced relatively stationary supports, a shaft extending between said supports, a bushing disposed on said shaft and floating thereon, means for relatively rigidly connecting said bushing with said arm, spring means disposed on said shaft on either side of said bushing and means disposed on said shaft for compressing each spring means against said bushing, and means for actuating said vibrator to vibrate said operating unit longiextending air-pervious material-receiving decky disposed above a resistance pack which forms an operating unit therewith and having means for feeding raw coal onto said deck at one end which forms the feed end thereof, relatively stationary supports disposed above said operating unit, resilient hanger means secured to and downwardly depending from said supports for suspending said operating unit at an incline with the feed end disposed at a higher level than the opposite end which forms the coal discharge end thereof, said incline being at an angle at which gravitational force will normally tend to move said operating unit causing sagging thereof forwardly away from said means for feeding raw coal onto the feed end thereof, means forming an arm disposed at the feed end of said operating unit and longitudinally rearwardly extending therefrom under` one of said stationary supporting members, a

bushing disposed on said shaft about midway thereof and oating thereon, means for relatively rigidly connecting said bushing with said arm which extends rearwardly from said operating unit underneath said means for feeding raw coal thereto, spring means disposed on said shaft-on either side of said bushing, means disposed on said shaft for compressing each spring means against said bushing, an unbalanced weight vibrator solely supported by and secured lto said arm at the free end thereof, and means for actuating said vibrator t'o vibrate said operating unit longitudinally for the two-fold purpose of imparting4 mechanical mobility and buoyant fluidity to the material particles on said deck and to cause particles of intermediate specific gravities to move downwardly through said air-pervious deck plate and through said resistance pack for downward discharge therefrom whereby clogging of said resistance pack is prevented to maintain its air resistance characteristics substantially constant.

13 REFERENCES crrnn Nluggs The following references are of record in the 21001356 111e o! this patent: 5 2,183,281 UNITED STA'I'ES PATENTS 5 2,374,865 Nuxzxberzq: Li Name A bDlaizelwg Y jqjflo Dfs': c: 3: m0 332339 1,843,405 Raw Feb. 2. 1932 Name Y Date Friend Aug. 30, 1932 Woock May 21, 1935 Ridley Dec. 12, 1939 Haworth May 1, 1945 FOREIGN PATENTS Country Date France June 30, 1934

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