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EP-4739438-A1 - CENTRIFUGAL SEPARATION DEVICE AND METHOD

EP4739438A1EP 4739438 A1EP4739438 A1EP 4739438A1EP-4739438-A1

Abstract

A centrifugal separation device (100, 900) comprises a vessel (120) having at least one sidewall (130) and a base (140) defining a chamber (150). A feed inlet (110) feeds a feed slurry (S) into the vessel (120). A particle separator (160) is located substantially in the middle of the chamber (150). The particle separator (160) is configured to separate low density and/or fine particles from the feed slurry (S). The vessel (120) is rotatable about an axis (170) to induce a centrifugal force on the feed slurry (S) in the chamber (150) such that high density and/or coarse particles in the feed slurry move from the particle separator (160) towards the at least one sidewall (130). An internal chamber (180) delivers fluidisation fluid into the chamber (150). The sidewall (130) and particle separator (160) are connected to drive systems (200, 210) for rotation relative to each other.

Inventors

  • GALVIN, KEVIN PATRICK

Assignees

  • The University of Newcastle

Dates

Publication Date
20260513
Application Date
20240626

Claims (20)

  1. 1. A centrifugal separation device comprising: a vessel having at least one sidewall and a base defining a chamber; a feed inlet for feeding a feed slurry into the vessel; and a particle separator located substantially in the middle of the chamber, wherein the particle separator is configured to separate low density and/or fine particles from the feed slurry; wherein the vessel is rotatable about an axis to induce a centrifugal force on the feed slurry in the chamber such that high density and/or coarse particles in the feed slurry move from the particle separator towards the at least one sidewall.
  2. 2. The centrifugal separation device of any one of preceding claims, wherein the particle separator is located adjacent or mounted to the base and/or is mounted for rotation with the vessel.
  3. 3. The centrifugal separation device of any one of claims 1 to 4, wherein the at least one sidewall or the particle separator is rotatable relative to the other.
  4. 4. The centrifugal separation device of claim 3, wherein the at least one sidewall and particle separator are rotatable at different speeds to each other.
  5. 5. The centrifugal separation device of claim 3 or 4, wherein: the at least one sidewall and particle separator are operably connected to a first drive system and a second drive system, respectively, for rotation at different speeds to each other; the first drive system comprises a first drive shaft connected to the at least one sidewall and a first drive motor operably connected to the first drive shaft to rotate the at least one sidewall; and the second drive system comprises a second drive shaft connected to the particle separator and/or base and a second drive motor operably connected to the second drive shaft to rotate the particle separator and/or base.
  6. 6. The centrifugal separation device of any one of the preceding claims, wherein the at least one sidewall comprises an internal chamber for receiving a fluidisation fluid from a fluidisation source and one or more fluidisation outlets for delivering the fluidisation fluid under pressure into the chamber.
  7. 7. The centrifugal separation device of any one of the preceding claims, wherein the at least one sidewall is movable relative to the base to create a gap such that an underflow of the high density and/or coarse particles escapes from the chamber.
  8. 8. The centrifugal separation device of any one of claims 1 to 6, wherein the at least one sidewall is rotatable relative to the base such that an underflow of the high density and/or coarse particles escapes intermittently or periodically as the at least one sidewall rotates relative to the base
  9. 9. The centrifugal separation device of claim 8, wherein a mechanical seal is provided between the at least one sidewall and the base, the mechanical seal comprising one or more openings to permit the underflow to escape the chamber at predetermined intervals.
  10. 10. The centrifugal separation device of claim 9, wherein the mechanical seal is formed by an edge of the at least one sidewall in contact with a track formed at an edge of the base, wherein the at least one sidewall edge is movable along the track and wherein the one or more openings are formed in the at least one sidewall edge and/or the track.
  11. 11. The centrifugal separation device of any one of claims 1 to 6, wherein the base comprises one or more discharge outlets adjacent the at least one sidewall to remove an underflow of the high density and/or coarse particles.
  12. 12. The centrifugal separation device of claim 11, wherein the base comprises a fluidisation conduit for delivering fluidisation fluid to the chamber, the fluidisation conduit being in fluid communication with the one or more discharge outlets to wash the underflow prior to removal, and wherein the fluidisation fluid flows against the direction of flow of the underflow.
  13. 13. The centrifugal separation device of any one of the preceding claims, comprising a baffle between the particle separator and the at least one sidewall, wherein an inner zone is formed between the particle separator and the baffle and an outer zone is formed between the baffle and the at least one sidewall.
  14. 14. The centrifugal separation device of claim 13, wherein the baffle comprises a frame having a plurality of inclined channels to permit the feed slurry to flow between the inner zone and the outer zone.
  15. 15. The centrifugal separation device of claim 13 or 14, wherein one or more ribs are connected to the baffle and/or base for promoting mixing and even rheology of the feed slurry flowing adjacent the at least one sidewall.
  16. 16. The centrifugal separation device of any one of the preceding claims, wherein: the particle separator comprises one or more particle separator assemblies, the particle separator being mounted to a drive shaft comprising an internal conduit; each particle separator assembly comprising one or more inclined channels in fluid communication with the internal conduit at a first end and in fluid communication with the chamber at a second end for releasing high density and/or coarse particles into the chamber; and the internal conduit is in fluid communication with at least one overflow launder for removing low density and/or fine particles.
  17. 17. The centrifugal separation device of any one of the preceding claims, comprising a deflector for directing the feed slurry from the feed inlet towards the at least one sidewall.
  18. 18. A method for separating fine particles from a feed slurry containing a mixture of low density and/or fine particles and high density and/or coarse particles, comprising the steps of: feeding a feed slurry into a vessel, wherein the vessel comprises at least one sidewall and a base defining a chamber; rotating the vessel about an axis to induce a centrifugal force on the feed slurry such that high density and/or coarse particles in the feed slurry move towards the at least one sidewall; and separating low density and/or fine particles from the feed slurry with a particle separator located substantially in the middle of the chamber.
  19. 19. The method of claim 18, comprising rotating the at least one sidewall relative to the particle separator.
  20. 20. The method of claim 18 or 19, comprising rotating the at least one sidewall and particle separator at different speeds to each other.

Description

Centrifugal Separation Device and Method Field of the Invention [0001] The invention relates to a centrifugal separation device and in a particular to a centrifugal separation device using closely spaced channels to achieve separation of a mixture of denser and less dense particles in a fluid feed. The invention has been developed primarily for use as a separation device for removing ultrafine particles typically less than 10 microns from a feed slurry suspension and will be described hereinafter by reference to this application. However, it will be appreciated that the invention may be used to separate fine or finer particles from coarser particles in a suspension. Background of the Invention [0002] The following discussion of the prior art is intended to present the invention in an appropriate technical context and allow its advantages to be properly appreciated. Unless clearly indicated to the contrary, however, reference to any prior art in this specification should not be construed as an express or implied admission that such art is widely known or forms part of common general knowledge in the field. [0003] Throughout this specification, and in the claims, the term “particles” is used in a broad sense to refer not only to discrete items of solid matter but also to aggregated items of solid matter, and discrete or aggregated bubbles or drops of liquid material. [0004] Enhanced gravity separation is concerned with the separation of particles on the basis of density, often requiring the hydrodynamic suppression of the effects of particle size. Enhanced gravity separation methods utilise centrifugal forces to promote the separation of ultrafine particles, typically down to 0.01 mm (10 microns). These devices operate according to the principles of solid-liquid fluidised beds. Through an increase in G-forces, higher settling velocities and hence higher solids rates are achieved. With the higher G-force generated within the enhanced gravity separation device, the intermediate regime of settling shifts to finer particles, which in turn reduces the dependence of the particle settling velocity on particle size for those finer particles. Hence, the centrifugal force suppresses the effects of particle size, in turn promoting centrifugal separation below 0.100 mm and often down to 0.01 mm. [0005] An enhanced separation device, called a graviton, developed by the inventor effectively uses a reflux classifier located within a centrifuge to achieve the separation of particles based on density using elevated G-forces created by high speed rotation, as described in PCT Application No. PCT/AU2011/000350, published as PCT Publication No. WO 2011/120078, the disclosure of which is hereby incorporated by reference. The reflux classifier has a vessel with a system of inclined channels, where a base of the vessel is shaped like a cone to funnel material (higher density and coarser particles) towards the underflow and an overflow launder located at the top above the inclined channels. In the graviton, the vertical axis of the reflux classifier is in effect rotated 90° so that the axis is located radially from the vertical shaft of the centrifuge. [0006] The elevated G forces in the graviton combine with the hydrodynamic advantage of inclined channels to achieve a vastly higher capacity advantage than what is possible by the G forces alone, over and above what is possible by conventional sedimentation. For example, if the capacity advantage of a 50G system (i.e. centrifugal acceleration is 50 x 9.8 ms-2) is 50-fold and the capacity advantage of the inclined channels is 20-fold, then the synergy delivers a capacity advantage approaching up to 50 x 20 = 1,000 fold, so the combination has considerable advantage over other technologies that only incorporate G forces and not inclined channels. The box-type design, combined with closely spaced channels, delivers the benefits of the synergy by driving the separation predominantly in the radial direction, rather than permitting the additional degree of freedom in the tangential direction. [0007] While the graviton is effective in achieving separation of ultrafine particles, it is desirable to further improve the design of the graviton to increase its efficiency and operation, as well as reducing the complexity of the device. [0008] It is an object of the present invention to overcome or substantially ameliorate one or more of the disadvantages of prior art, or at least to provide a useful alternative. It is an object of the invention in at least one preferred embodiment to provide an improved centrifugal separation device and method that has greater efficiency in separating ultrafine particles from a feed slurry suspension. This action is often referred to as “desliming”. Summary of the Invention [0009] A first aspect of the invention provides a centrifugal separation device comprising: a vessel having at least one sidewall and a base defining a chamber; a feed inlet for feeding a