GB1558433A

GB1558433A - Separators for separating high density solid particles from a slurry

Info

Publication number: GB1558433A
Application number: GB14512/77A
Authority: GB
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1976-05-10
Filing date: 1977-04-06
Publication date: 1980-01-03
Also published as: DE2719596B2; IN155912B; ES458619A1; CA1066231A; PL197964A1; AU2362577A; FR2350883B1; NL7703322A; FR2350883A1; AU502437B2; DE2719596A1; ZA772714B

Description

(54) IMIPROVEMENTS IN OR RELATING TO SEPARATORS FOR SEPARATING HIGH DENSITY SOLID PARTICLES FROM A SLURRY (71) We, FMC CORPORATION, a Corporation organised and existing under the laws of the State of Delaware, United States of America, of 200 E. Randolph Drive, Chicago, State of Illinois, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to separators for separating high density solid particles from a slurry.

According to the present invention, there is provided a separator for separating high density solid particles from a slurry containing high and low density solid particles said separator compirsing an imperforate deck with a support surface, a plurality of parallel spaced riffles extending upwardly from the deck support surface, said surface being sloped downwardly from a feed side for receiving the slurry to a slurry discharge side so that the slurry flows transversely across said riffles and carries the low density particles therewith said riffles being arranged to restrain the high density particles in the interstices formed therebetween, means for resiliently supporting said deck, and an exciter coupled to the deck for generating and transmitting vibration thereto along a predetermined line of attack axis to progressively advance the high density particles along the deck in a direction generally parallel to said riffles, said predetermined line of attack axis having a vertical component and said exciter being capable of accelerating the deck to a maximum vertical acceleration that is greater than the acceleration of gravity whereby the high density particles progress generally parallel to said riffles in a series of hops induced by the deck vibrations.

According to another aspect of the present invention, there is provided a method of separating high density solid particles from a slurry containing high and low density solid particles said method comprising feeding the slurry at a predetermined rate of flow onto an inclined support surface, subjecting the slurry on the support surface to gravitational forces that cause the slurry to flow downwardly along the inclined support surface towards a discharge side thereof, restraining the flow of high density solid particles on the support surface in the direction of slurry flow by a series of parallel spaced riffles that project upwardly from the support surface and extend transversely of the direction of slurry flow, and progressively advancing the high density solid particles along the support surface by vibrational impulses in a direction generally parallel to the riffles towards a discharge end of the support surface, the vibrational impulses being directed along a predetermined line of attack axis that has a vertical component with the vibrations having a maximum vertical acceleration greater than the acceleration of gravity.

An embodiment of the invention will now be described by way of example only with reference to the accompanying diagrammatic drawings, in which Figure 1 is a perspective view of a concentrating table type of separation in accordance with the invention together with an associated discharge trough and a discharge channel; Figure 2 is a side elevation of the separator shown in Figure 1, with the discharge trough and the discharge channel broken away but indicated in phantom line: Figure 3 is a fragmentary end elevation of the separator shown in Figure 1, and Figure 4 shows schematically the action that is induced by the deck vibration to move a single high density solid particle.

With reference to Figure 1, a separator 10 has an imperforate deck 11 with a sup port surface 12. A head end wall 13 and a feed side wall 14 enclose a portion of the deck, while a discharge end 15 and a dis charge side 16 of the deck remain open.

A series of parallel spaced riffles or ribs 18 and 19 project upwardly from the deck support surface and extend generally per pendicular to the head end wall. The riffle patterns are designed in accordance with the characteristics of the material being handled.

Usually the riffles are approximately 1/4" to 1" high at the head end wall and taper down to zero before reaching the discharge end. The riffles 19 are spaced about every fourth riffle 18, and these riffles are higher than the riffles 18 to prevent large high density particles from rolling transversely across the riffles when the interstices between riffles are filed with fine high density particles. Such fines tend to settle beneath the large particles and thereby elevate the large particles to a higher stratum. The shallow riffles 18 tend to spread the band of particulate material over a wider area to facilitate segregation, while the higher riffles provide pools for the settlement of fine grains.

The support surface 12 of the deck 11 slopes downwardly from the feed side wall 14 to the discharge side 16, in a direction lateral to the riffles 18 and 19. The angle 20, as shown in Figure 3, that is located between the transverse slope of the deck and the horizontal, ranges between 40 to 120, in the direction lateral to the riffles. The deck top surface is upwardly inclined from the horizontal by an angle 21, as shown in Figures 2, ranging between 1/2" to 20, in the direction parallel longitudinally of the riffles, from the head end wall 13 towards the discharge end 15.

A pair of longitudinal frame members 23 and 24, shown in Figures 2 and 3, project downwardly, perpendicular to the deck 11.

A series of transverse frame members 25, 26, 27, 28, 29 and 30 project laterally outward from the frame member 23 to support the discharge side portion of the deck, and a series of transverse frame members 31 project laterally outward from the frame member 24 to support the feed side portion of the deck. A forward bracket 32 and a rear bracket 33 extend transversely between the longitudinal frame members. Between these brackets, an exciter 34 is resiliently mounted by a drive springs 35 and 36, that are arranged to flex in a direction along a predetermined line of attack axis 37. This axis is inclined at an angle 40 of about 20 degrees to the deck support surface 12, in a plane that extends longitudinally parallel to the riffles 18 and 19 and perpendicular to the support surface, and the axis has a vertical component.The exciter has a hous ing 38. within which rotatable eccentric weights are located, and these weights are driven through a suitable drive by an elec tric motor 39 that is mounted on the exciter housing. The exciter is capable of generat ing a maximum vertical acceleration on the deck within a range approximately between 1.25 to 2 times the acceleration of gravity at 0.4 inch stroke. The exciter operates at 1100 cycles per minute. Such exciters are standard commercial items, and a suitable exciter is the "MF-600" Exciter, manufactured by the MHE Division of FMC Corporation, Homer City, Pennsylvania.

The deck 11 is resiliently supported to enable it to vibrate freely. A pair of brackets 41, only one of which is shown in Figure 2, are mounted to the deck adjacent the feed end thereof. These brackets are mounted upon coil compression springs 42 that rest upon adjustable seats 43. The seats are attached to bolts 44 that are threadably fitted within sleeves 45, and each of these sleeves are mounted to a channel post 46. The posts are mounted upon a support frame 47 and these posts are braced longitudinally by the braces 48. Near the deck discharge end 15, a bracket 50 projects outwardly from the longitudinal frame member 23. This bracket rests upon a coil compression spring 51, that is seated upon an adjustable seat 52. The seat is attached to a bolt 53, that is threadably fitted within a sleeve 54.This sleeve is mounted to a channel post 55, that projects upwardly from the support frame 47. The post 55 is supported in a direction longitudinally of the deck by a brace 56. Similarly, a bracket 58 projects outwardly from the longitudinal frame member 24, and this bracket rests upon a coil compression spring 59, that is seated upon an adjustable seat 60. This seat is attached to a bolt 61, that is threadably fitted within a sleeve, not shown. A channel post 62 projects upward from the support frame 47 to support the sleeve, not shown. It should be understood that the above described deck mounting merely represents one form in which the deck could be resiliently supported. It could also be suspended by springs and cables from a ceiling.

Looking again at Figure 1, a feed channel 64 is positioned for feeding a slurry mixture upon the deck support surface 12, at a location adjacent the corner of the head end wall 13 and the feed side wall 14. Additional water is fed from the deck support surface from spray nozzles in the headers 65 and 66, that are positioned adjacent the feed side wall 14. Risers 67 and 68 supply water to the header 65, and a riser 69 supplies water to the header 66. A discharge trough 70 is separate from the deck 11, but this trough is positioned adjacent the discharge side 16, to collect low density particles and liquid carrier, overflowing from the deck. A drain channel 71 extends, from the lowermost portion of the trough, to a suitable discharge location.

In operation, the separator 10 is particularly suitable for washing and cleaning coal by removing rock, slate and pyritic sulfur. Such refuse has a higher density than the coal and is discharged at the discharge end 15, while the coal and water flow over the discharge side 16, into the discharge trough 70 and the drain channel 71.

The separator can also be used for separating various ores, in which case the high density mineral concentrate is discharged from the discharge side. In the following description of the method of operation, reference will be made to high or low density particles and it will be understood that such separation can be made for various materials.

A slurry, that includes both high density solid particles and low density solid particles suspended in a liquid carrier, is fed at a predetermined rate of flow, from the slurry feed channel 64, onto the deck support surface 12. Gravitational forces cause the liquid carrier and the low density particles to flow, transversely of the riffles 18 and 19, down the inclined deck, and across the tops of the riffles in a direction towards the discharge side 16, while the high density particles settle in the interstices between riffles. The riffles restrain the high density particles from flowing transversely of the riffles, and the vibrational impulses, imparted to the deck 11 by the exciter 34, advance the high density particles, along the support surface, towards the discharge end 15. in a direction generally parallel to the riffles.

With reference to Figure 4, the action of a single high density particle, moving along the deck support surface 12, towards the discharge end 15 is illustrated. At the beginning of a vibration cycle, the deck is in the bottom position. The particle is in contact with the deck support surface, from the lowest point A to approximately the midpoint of the vibration stroke, near the neutral deck position. At this point, the particle has been accelerated to its maximum velocity and leaves the support surface on a free flight trajectory, while the support surface is decelerating from point B to point C. The particle continues on its trajectory, as the deck returns to the bottom position, and the particle rejoins the support surface, at point A,, to complete one vibration cycle.

It should be noted that the deck is elevated in a plane perpendicular to the transversely inclined support surface, but the particle falls in a vertical plane. Thus, there is a slight amount of lateral travel for the particle with each vibration cycle.

The above description of single particle action is theoretical and does not take into consideration the dampening effect of the liquid carrier. Such particle action might be achieved near the deck discharge end 15, but in the area where the slurry flows transversely across the deck support surface 12, there is considerable agitation and turbulence. Such agitation and turbulence facilitate stratification, and there is a rapid conveying action for high density particles toward the deck discharge end.

The feed angle, or the angle 40 at which the predetermined line of attack axis 37 is inclined to the deck support surface 12, is preferably about 20 degrees to the deck support surface, in a plane that extends longitudinally parallel to the riffles and perpendicular to the support surface. The deck vibrations generated by the exciter 34 have a maximum vertical acceleration within an approximate range of between 1.25 to 2 times the acceleration of gravity. This acceleraion enables the high density particles to advance in a series of rabbit-like hops along the deck, but does not elevate the particles to such an extent that a considerable amount of high density particles jump the riffles 19.

While the high density particles are conveyed towards the deck discharge end 15 for separate disposal, the low density particles and liquid carrier flow, transversely over the riffles 18 and 19, towards the deck discharge side 16. Upon overflowing this side of the deck, the liquid carrier and low density particles are received in the discharge trough 70, from which they are conveyed through the drain channel 71.

While the foregoing described embodiment is directed to a single deck separator 10, the present invention can also be applied to a double deck separator, as described in United States Patent Specification No.

3,075,644. The exciter can be mounted above the decks to be vibrated, and the separator assembly can be suspended by cables and springs from a ceiling.

To summarise, the capacity of the separator particularly described is increased by increasing the velocity of high density solid particles moving towards the discharge end of the deck. This increase in particle velocity is achieved by vibrating the deck along an inclined line of attack axis with a maximum vertical acceleration greater than the acceleration of gravity. This causes the particles to leave the deck surface on a free flight trajector with each vibration of the deck and thus, the particles travel in a series of rabbit-like hops towards the discharge end of the deck. Such vibratory movement of the deck enables a greater particle velocity than can be achieved bv horizontal reciprocation of the deck. This particle velocity effects the rate at which the slurry can be fed onto the deck in order to avoid a build-up of solid particles on the deck.With horizontal reciprocation of the deck, the slurry feed rate must be limited to prevent such particle build-up.

WHAT WE CLAIM IS: 1. A separator for separating high density solid particles from. a slurry containing high and low density solid particles, said separator comprising an imperforate deck with a support surface, a plurality of parallel spaced riffles extending upwardly from the deck support surface, said surface being sloped downwardly from a feed side for receiving the slurry to a slurry discharge side so that the slurry flows transversely across said riffles and carries the low density particles therewith, said riffles being arranged to restrain the high density particles in the interstices formed therebetween. means for resiliently supporting said deck, and an exciter coupled to the deck for generating and transmitting vibrations thereto along a predetermined line of attack axis to progressively advance the high density particles along the deck in a direction generally parallel to said riffles, said predetermined line of attack axis having a vertical component and said exciter being capable of accelerating the deck to a maximum vertical acceleration that is greater than the acceleration of gravity whereby the high density particles progress generally parallel to said riffles in a series of hops induced by the deck vibrations.

2. A separator according to claim 1.

wherein the exciter is operative to accelerate the deck to a maximum vertical acceleration of between 1.25 and 2.0g.

3. A separator according to claim 1 or claim 2, wherein said predetermined line of attack axis is inclined at an angle of about 20 degrees to the deck support surface in a plane that extends longitudinally parallel to the riffles and perpendicular to the support surface of the deck.

4. A separator according to claim 3, wherein said deck support surface slopes downwardly from the horizontal by an angle of between 4" and 12" in the direction of slurry flow laterally to the riffles.

5. A separator according to claim 4 wherein said deck support surface slopes upwardly with respect to the horizontal from a head end towards a discharge end by an angle of between 1/2" and 2" in a longitudinal direction parallel to the riffles.

6. A method of separating high density solid particles from a slurry containing high and low density solid particles, said method comprising feeding the slurry at a predetermined rate of flow onto an inclined support surface, - subjecting the slurry on the support surface to gravitational forces that cause the slurry to flow downwardly along the inclined support surface towards a discharge side thereof, restraining the flow of high density solid particles on the support surface in the direction of slurry flow by a series of parallel spaced riflles that project upwardly from the support surface and extend transversely of the direction of slurry flow, and progressively advancing the high density solid particles along the support surface by vibrational impulses in a direction generally parallel to the riffes towards a discharge end of the support surface, the vibrational impulses being directed along a predetermined line of attack axis that has a vertical component with the vibrations having a maximum vertical acceleration greater than the acceleration of gravity.

7. A method according to claim 6, wherein said predetermined line of attack axis is inclined at an angle of about 20" to the support surface in a plane that extends longitudinally parallel to the riffes and perpendicular to the support surface.

8. A method according to claim 6 or claim 7, wherein the vibrations have a maxiumum vertical acceleration of between 1.25 and 2.0g.

9. A method of separating particles from a slurry, substantially as hereinbefore described with reference to the accompanying drawings.

10. A separator substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. particle velocity effects the rate at which the slurry can be fed onto the deck in order to avoid a build-up of solid particles on the deck. With horizontal reciprocation of the deck, the slurry feed rate must be limited to prevent such particle build-up. WHAT WE CLAIM IS:

1. A separator for separating high density solid particles from. a slurry containing high and low density solid particles, said separator comprising an imperforate deck with a support surface, a plurality of parallel spaced riffles extending upwardly from the deck support surface, said surface being sloped downwardly from a feed side for receiving the slurry to a slurry discharge side so that the slurry flows transversely across said riffles and carries the low density particles therewith, said riffles being arranged to restrain the high density particles in the interstices formed therebetween. means for resiliently supporting said deck, and an exciter coupled to the deck for generating and transmitting vibrations thereto along a predetermined line of attack axis to progressively advance the high density particles along the deck in a direction generally parallel to said riffles, said predetermined line of attack axis having a vertical component and said exciter being capable of accelerating the deck to a maximum vertical acceleration that is greater than the acceleration of gravity whereby the high density particles progress generally parallel to said riffles in a series of hops induced by the deck vibrations.

2. A separator according to claim 1.