US1354063A - Apparatus for grading finely-comminuted materials - Google Patents

Description

c. Q. PAYNE. APPARATUS FOR GRADING ,FINELY COMMINUTED MATERIALS.

APPLICATION FILED AUG-7, I919.

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zm Paw By Attorney I III C. Q. PAYNE. APPARATUS FOR G RADING FINELY COMMINUTED MATERIALS.

APPLICATION FILED AUG-7, I919.

Patented Sept. 28, 1920.

2 SHEETS-SHEET 2- Invenfo 5n 4. M diam filer-hey UNETED STATES PATENT OFFICE;

CLARENCE Q. PAYNE, OF NEVJ' YORK, N. Y.

Specification of Letters Patent.

Patented Sept. 28, 1920.

Application filed August 7, 19:19. Serial No. 315,944.

To all whom it may concern:

Be it known that I, CLARENCE Q. PAYNE, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Apparatus for Grading Finely-Comminuted Materials, of which the following is a specification.

This invention relates to apparatus for the separation of finely divided or comminuted materials of various kinds into a series of groups of different sized particles without the use of screens.

In my copending application 277,724, I have described an invention which embraces a novel method of and apparatus for grading quite finely divided material, which consists in acting upon it while it is conveyed lengthwise, upon an endless belt, preferably transversely inclined, so that the material becomes stratified in transversely disposed grooves in the belt, with the coarser or granular particles on top, then discharging decreasing sized groups of granular particles along the upper flight of the belt, while the finest particles are retained upon the belt by surface adhesion, aided by the static charge generated by its own air friction, until carried to the lower flight of the belt, where they are removed.

One object of the present invention is to provide an improved apparatus based on the above method.

Another object is an apparatus for grading finely subdivided or comminuted materials, and capable of extending the sizing action in the direction of the finest sizes.

A still further object is to provide means for stratifying the particles while being conveyed upon an endless belt, preparatory to sizing them.

Other objects will be apparent from the description.

For a fuller understanding of the invention, reference is had to the accompanying drawings, in which- Figure 1 is a longitudinal section through an apparatus embodying the invention;

Fig. 2 is a sect-ion on the line 10-10, Fig. 1;

Fig. 3 is fragmentary sectional view on an enlarged scale of the belt. Fig. 4 is a longitudinal view of a special form of the invention in which longitudinal vibration is imparted to the belt.

Figs. 59 illustrate different means for removing the'finer particles from the lower flight of the belt by the application of various dispersive forces.

The invention is especially intended for grading finely crushed materials, in the grading of which only a limited number of roups of granular particles is required. r or this purpose I find that an endless belt operated at a high speed in such a position that the transverse lines of the belt surface are horizontal, has certain advantages over an endless belt having its upper flight transversely inclined at a uniform or at a progressively varying angle. The belt may also be operated in a longitudinally inclined position, although preferably with the transverse elements of the belt surface horizontal.

In Figs. '1 and 2 is shown a grading device comprising an endless belt, 1 mounted upon pulleys 2 and 3 for travel in a substantially horizontal plane. The pulleys are supported in a suitable frame a, and the casing 5 serves to completely inclose the endless belt. Bctween the end pulleys 2 and 3, the guide rollers 77 and 8-8 supportthe upper and lower flights respectively. A suitable belt tightener 6 serves to maintain the proper tension upon the belt. The material to be graded is fed from a hopper 9 through a regulating gate 12 to the feed drum l3, and thence by guide plate 14 upon one end of the belt. By suitable operating mechanism the belt is driven a high speed in the direction indicated by the arrow.

lVhile in the broader aspect of the invention the surface of the belt may be ungrooved, I preferably provide it with transverse grooves placed centrally and shorter than the width of the belt, so as to leave an ungrooved portion l5-15 at each edge. This arrangement has the following purpose: When the belt 1 travels at high speed, its grooved surface sets up air currents which tend to disperse the particles sidewise as they are fed upon the belt. By leaving the edge portions 15 of the belt ungrooved, the effect of the air currents is here largely avoided. As a further means of checking the disturbing effect of these air currents, I find it advisable to employ stationary protecting wings or shields 16-16, which are supported from the casing 5 and are held in close proximity to the ungrooved ever, the transverse position of the grooves,

because they bring about the separation of the different sized granular particles after stratification more expeditiously and more effectively than if the grooves were placed longitudinally or diagonally upon the belt surface. The progressively increasing inclination of the sliding surfaces of the grooves 17 17 causes progressively increasing differences of statical moments and of frictional resistances among the different sized particles which are disposed in strata in the grooves. The resulting differences in the resistance to motion of the different sized particles cause the successive strata to separate themselves from each other with has a three fold purpose.

least mechanical interference.

While the shape of the grooves may be widely varied,'I find it convenient to so arrange their bounding faces that one of them formsan acute angle with the belt surface, while the other mayform approximately a right angle therewith. The inclined faces of the grooves, on reaching the discharge endof the belt, then form sliding planes or separating surfaces of increasingly steeper inclination along the curved surface of the pulley 3, as illustrated clearlyin Fig. 3. Here the coarsest particles are the first to detach themselves from the belt, and to be thrown off in definite directions, and in groups of decreasing sized particles, as shown diagrammatically in F 3.

.One particular advantage of this arrangement is the relatively small wear to which the surface of the belt is subjected. The distance which the coarse or granular particles move upon the belt surface while undergoing separation is merely that alongthe sliding surfaces 1717 of the grooves,

, The. different sized particles are collected in'a series of separate chutes 185-18 at the discharge end of the belt. While I have indicated only three of such chutes, it is obvious that the sub-division may be carried still farther. The size of the discharge pulley .3 may also be increased, or the curve through which the belt passes at its discharge .end may be varied in different ways so that the amount of the grading of the granular particles influenced by the separating forces exerted upon them may be increased as desired. 7

The high speed at which the belt is driven It enables the stream of the material '.-to immediately spread out'in a thin layer as it comes in contact with the belt. It also aids'in bringing about stratification of the material in the grooves, and it tends to increase the statlc surface adhesion of the very finely comminuted particles to the surface of the belt. The static surface charge of the belt is generatedpartly by the friction of the air againstthe surface of the belt when in motion and partly by the approach, pressure and recession of two electrically unlike substances, such as a rubber or leather belt, and'an iron pulley when the former passes rapidly around the latter. This charge is thus self-induced and causes the finer particles to be held to the belt by surface adhesion.

For. certain kinds of material the high speed of the belt, inconnection with the slight sagging, as it passes over the guiderollers 7+7, Fig. 1, tends to set the particles in sufficient vertical vibration to bring about the desired stratification when the feed-stream delivered upon the belt is sufiiciently thin. The resulting freedom of movement of the particles among themselves thus causes the coarsest particles to appear on top, while the smallerparticles falling between their interstices, occupy succeeding lower levels until the finest particles of all rest in immediate contact with the surface of the belt along the bottoms of the grooves. This stratification is indicated diagrammatically in Fig. 3.

F or still other varieties of materials, I have found that a more pronounced amount of vibration is desirable, and for such I prefer to apply the means illustrated in Fig. at. Here the end pulley bearings :202O may be supported by means of flexible hangers 219-21, and horizontal springs 22-22 support and adjust the proper tension of the belt 24L. ,An eccentric weight 25 is rigidly connected to the innercircumference of the pulley 26 at the feed end of the belt. The rotation-of this weight as the pulley 26 revolves about its axis causes the tension of the belt to be rapidly and alternately increased and diminished, The amount of the vibrating movement of the belt may be regulated to the required degree by varying the weight 25, and the compression of the springs 2222. This vibration is transmitted to the other end pulley 27 by means of the belt 24. The entire belt is thus set in rapid longitudi nal vibration, while at the same time it is traveling about its end pulleys 26 27. In this way the particles fed upon the belt may be given an increased amount of vibration in a longitudinal directionover that attained merely by the rapid motion of the belt itself, and are thus enabled to stratify themselves in the manner illustrated in Fig. 3, even when fed in a comparatively thick feedstream in the grooves of the belt.

It is important'that no violent shocks or jars be applied to the pulley 27 at the discharge end of the belt, in order to avoid removal of the finest particles held to the belt surface prematurely. For this reason I consider it advantageous to apply the vibrating effect upon the belt to the feed end by means of a gradual and easy reciprocating motion, such as is obtained by the revolving eccentric weight 25, and also to diminish the amount of motion transmitted to the pulley 27 by the stretch of the belt intervening between the two end pulleys. While I consider the means described above preferable for my purpose, yet other means may also be employed to bring about the longitudinal vibration of the belt in a manner and for the purpose described. Such additional means I consider to be within the scope of my invention.

As explained in my co-pending application above referred to, the effect of surface adhesion is to cause the very fine particles in contact with the belt to be retained upon it until they are removed from the lower flight of the belt by a greater force than that operating to retain them.

As the belt passes around thepulley 3, Fig. 1, the coarsest particles forming the upper layers of the stratified material are the first to be discharged. Then follow successively smaller or finer particlea'until all those which respond to differences of statical moments and of frictional resistances, aided by centrifugal force, have been discharged. Those still finer dustlike particles which resist the force of gravity and of centrifugal force, and are held upon the belt by surface adhesion, are then carried over the curved surface of the pulley 3, and occupy inverted positions when they reach the lower flight of the belt.

The high speed of the belt, while increas ing the force of attraction which is exerted upon the very fine particles, also increases the surface exposed per unit of time to the particles subjected to the force of adhesion. The grooving of the belt surface still further increases the effective surface of attraction.

A special advantage of my present inven tion consists in the extreme sub-division which can be efiected among the very fine particleswhich are retained upon the belt by surface adhesion. WVhen conveyed to the lower flight, these fine particles may then be removed by various means, for example, by the use of cam-shaped rollers 28 and 29 to vibrate the belt, as shown in Figs. 1 and 4, by means of air jets, shown in Figs.-5 and 6, by means of a series of grounded metal points to dissipate the static belt charge shown in Figs. 7 and 8, or by induction from a wire carrying a high tension alternating current placed close to the belt surface shown in Fig. 9. Any of the above devices may be applied in more than one position, and may also be variedin their effects in applying them. For the purpose of illustration I have shown at 2829, Fig. l, camshaped rollers which cause the belt to vibrate vertically at two places along its lower flight. By placing the cam-rollers in different relation to the belt, so as to var the amount of the vibration at different parts of the belt, the group of fine particles removed by the rollers 28 may be somewhat coarser than the extremely fine particles removed by the cam roller 29, collected by the screw conveyer 30, and discharged at 31, while the finest of the end products is collected and removed at 32. By thus detaching the more easily removed particles, and therefore the coarser among them first, it is possible to segregate in this way groups of extremely minute particles more perfectly than has heretofore been possible by mechanical means.

I claim:

1. Apparatus for the sizing of finely comminuted material, comprising an endless belt and means for operating the belt to cause the finer particles to adhere to the surface thereof, means for varying the resistance to the motion of the different-sized granular particles along the discharge end of the belt, means for collecting separate groups of said granular particles and means for removing the finer particles adhering to the belt, from the lower flight thereof.

2. Apparatus for the sizing of finely comminuted material, comprising an endless belt and means for operating the belt to cause the finer particles to adhere to the surface thereof, means for varying the direction of discharge of the different sized granular particles of said material from the curved end of the belt by varying their statical moments and frictional resistances thereon, means for collecting separate groups of diminishing sized particles and means for removing the finer particles adhering to the belt from the lower flight thereof.

3. Apparatus for the sizing of finely comminuted material, comprising an endless belt having horizontal transverse grooves and means for operating the belt to cause the finer particles to adhere to the surface thereof, said grooves being shaped to gradually vary the resistance to the motion of the granular particlesof said material along the discharge end of the belt, means for collecting separate groups of granular particles and means for removing the finer particles adhering to the belt from the lower flight thereof.

4-. Apparatus for the sizing of finely comminuted material, comprising an endless belt having horizontal transverse grooves, means for operating the belt to cause the finer particles to adhere to the surface of the belt, means for imparting longitudinal impulses to one end support of the belt, means for collecting separate groups of diminishing sized granular particles discharged from the end. of the belt and means for removing the finer particles adhering to the belt, from the lower flight thereof.

.5. Apparatus for the sizing of finely comminuted material, comprising an endless belt having horizontal transverse grooves and means for operating the belt to cause the finer particles to adhere to the surface thereof, said grooves being shaped to gradually vary the resistance to the motion of the granular particles of said material along the discharge end of the belt, means for imparting longitudinal impulses to one end support of the belt, the said grooves being shaped to gradually vary the resistance to the motion of the granular particles of said material along the discharge end of the belt, means for collecting separate groups of granular particles and means for removing the finer particles adhering to the belt from the lower flightthereof.

6. Apparatus for the sizing of finely com minuted material, comprising an endless belt having horizontal transverse grooves, means for ope-rating the belt to cause the finer particles to adhere to the surface thereof, means for feeding the material upon one end of the belt, means for imparting longi tudinal impulses to one end supportof the belt to cause stratification of the material in .the grooves, said grooves being shaped to gradually vary the resistance .to the'motion of the granular particles of the material along the discharge end of the belt; means for collecting separate groups of said granular particles and means for removing the finer particles adhering to the belt from the lower flight thereof.

7. In apparatus for the sizing of finely comminuted material, an endless belt having transversely disposed grooves, each groove being defined by a wall substantially at a. right angle to the belt surface and a surface which forms an acute angle with the belt surface, and means for operating the belt to cause the finer particles to adhereto the surface thereof.

8. In apparatus for the sizing of finely comminuted material, an endless belt having transversely disposed grooves, each groove being defined by a wall substantially at a right angle to the belt surface and a surface which forms an acute angle with the belt surface, means for imparting impulses to one end support of the belt, means for operating the belt to cause the finer particles to adhere to the surface thereof and means for removing the finer particles adhering to the belt from the lower flight thereof.

9. In apparatus for the sizing of finely comminuted material, an endless belt havingtransversely disposed grooves alongits central portion, and whose edge portions are ungrooved in combination with air current protecting shields supported above the ungrooved edge portions of said belt.

10. Inapparatusfor the sizing of finely comminuted material, an endless belthaving transversely disposed grooves along its central portion and whose edge portions are ungrooved, each groove being defined by two faces, one approximately perpendicular and the other inclined to the belt surface and wind protecting shields supported above the u-ngrooved portions.

11. An apparatus for'the sizing of finely comminuted materials composed of various sized particles, comprising an endless belt, the transverse lines of whose surface are horizontal, means for rapidly moving the belt, means for charging the material upon one end of the belt, means acting upon the lower "flight .of the belt'to separately discharge groups of differentsized particles therefrom and means for separately receiving said groups.

12. An apparatus for the sizing of finely comminuted materials composed of various sized particles, comprising an endless belt the transverse lines of whose surface are horizontal, means for charging the material upon one end of the belt, means for stratifying the material upon the belt, means for separately receiving groups of different sized particles discharged from the curved surface at the end of the belt, means acting upon the lower flight of the belt to-separately discharge groups of different sized particles therefrom and means for sepa rately receiving said groups.

13. In apparatus for the sizing of finely comminuted material, an endless belt, means for rapidly moving the belt and means acting on different parts of the lower flight of the belt and in different degrees to sepa rately remove different sized particles therefrom.

14:. In the method of separating finely comminuted material according to size which consists in charging, the material upon an endless belt, rapidly moving the belt to causethe very fine particles to adhere to the surface ofthe belt and removing them from the lower flight thereof, the step which consists inacting differently on different parts of the lower flight of the belt to separately remove different sized particles therefrom.

15. An'endless belt, means for rapidly moving the belt and. means operating upon the lower flight of the belt for vibrating different portions thereof in different de grees.

16. vAn apparatus for sizing finely comminuted materials composed of various sized particles comprising an endless belt having transversely disposed horizontal grooves, means for rapidly moving said belt, means for feeding the material upon one end of said belt, means for longitudinally vibrating the belt to cause stratification of the particles with relation to their sizes Within said grooves, means for separately receiving groups of diminishing sized particles along the curved surface of the belt at its discharge end, and means for removing from the lower flight thereof a plurality of finer sizes adhering thereto.

In testimony Wheeroit I aflix my signature.

CLARENCE Q. PAYNE.

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