WO2009089589A1

WO2009089589A1 - A hydrocyclone separation apparatus

Info

Publication number: WO2009089589A1
Application number: PCT/AU2009/000049
Authority: WO
Inventors: Maurice Ross Munro
Original assignee: Ludowici Technologies Pty Ltd
Current assignee: Ludowici Technologies Pty Ltd
Priority date: 2008-01-16
Filing date: 2009-01-16
Publication date: 2009-07-23
Anticipated expiration: 2010-07-16

Abstract

A hydrocyclone separation apparatus which has a feed chute and a feed ramp in fluid communication with the feed chute. The feed ramp having a ramp side wall and a ramp base formed at an angle to the ramp side wall wherein the angle formed between the ramp side wall and the ramp base varies along a length of the feed ramp.

Description

A HYDROCYCLONE SEPARATION APPARATUS

FIELD OF THE INVENTION

The invention relates in general to a hydrocyclone separation apparatus. In particular, although not exclusively, the invention relates to the design of an inlet of a hydrocyclone separation apparatus.

BACKGROUND OF THE INVENTION Separation of different materials based on their physical properties is a frequently used process in mining and industrial applications. Hydrocyclones are useful for separating materials that are suspended in a flowing liquid, such as a mineral slurry, by size or particle density. The slurry enters at the top of an apex-down conical shaped chamber via a generally tangential inlet, which forces the slurry to spin inside the hydrocyclone. As the slurry spirals down the conical shape of the hydrocyclone, the reducing diameter creates strong centrifugal forces within the slurry. A cut point particle size is defined for a hydrocyclone in operation and is dependent upon the size and shape of the hydrocyclone and the slurry flow parameters. The particles that are larger than the cut point particle size are forced towards the walls of the hydrocyclone and travel down in a spiral path to an underflow discharge stream. The particles that are smaller than the cut point particle size migrate to the centre of the hydrocyclone where the axial flow direction is reversed, and move upwards as an overflow discharge stream.

In normal operation, an air core develops along the central axis of the hydrocyclone. The air core is established when the fluid at the axis of the hydrocyclone reaches a pressure that is less than atmospheric pressure, and extends from the underflow outlet to the overflow outlet. An air core that is unstable and/or is not concentric with the central axis of the hydrocyclone leads to inefficient separation when the overflow discharge stream is cut from the cyclone by a concentric mounted vortex finder.

Design of the hydrocyclone has a strong influence on the flow dynamics within the hydrocyclone and thus on the efficiency of the separation.

In particular, poor inlet design results in turbulence in the inlet area, which results in the misplacement of coarse particles to the overflow discharge stream due to disruption of the concentric flows around the lower cutting edge of the vortex finder. These inefficiencies of separation lead to greater production costs or loss of product.

Turbulence also results in greater wear to the hydrocyclone in an uneven pattern. This leads to higher maintenance costs and more frequent equipment down times as well as shorter equipment lifetimes. Turbulence may also reduce the capacity and throughput rate of the hydrocyclone or require higher pumping pressures and hence higher energy use. This increases production costs for the process. Traditional hydrocyclone inlet geometries have featured an outer wall tangential feed, however, this design has been found to cause excessive and uneven wear to the hydrocyclone and only allow low capacity. More recently, hydrocyclone feed inlets of an involute and scrolled geometry have been developed wherein a pipe containing hydrocyclone feed slurry is curved around the top of the hydrocyclone. The feed slurry continues along a feed ramp, which is angled down such that the slurry begins to follow a circular path prior to entering the hydrocyclone. Frequently, the width of the base of the feed ramp is tapered, although it remains substantially horizontal. These designs show high concentrations of wear at the point where the feed slurry enters the hydrocyclone off the bottom ledge of the involute and/or scroll inlet feed ramps. These high wear patterns of current hydrocyclone designs are indicative of an uneven solid distribution entering the hydrocyclone, which gives rise to a lack of concentricity of the air core of the hydrocyclone.

OBJECT OF THE INVENTION

It is an object of the invention to overcome or at least alleviate one or more of the above problems and/or provide the consumer with a useful or commercial choice.

DISCLOSURE OF THE INVENTION

In one form, although it need not be the only or indeed the broadest form, the invention resides in a hydrocyclone separation apparatus comprising: a feed chute; and a feed ramp in fluid communication with the feed chute, the feed ramp having a ramp side wall and a ramp base formed at an angle to the ramp side wall; wherein the angle formed between the ramp side wall and the ramp base varies along a length of the feed ramp.

Suitably, the ramp base is, at a point along the length of the feed ramp, substantially co-planar with an inner wall of a main body of the hydrocyclone separation apparatus.

Preferably, the angle between the ramp side wall and the ramp base increases along the length of the feed ramp. In a particularly preferred embodiment, the angle between the ramp side wall and the ramp base varies along the length of the feed ramp from substantially perpendicular to substantially linear.

In a preferred embodiment, the base of the feed chute is planar. It is particularly preferable that the cross sectional shape of the feed chute is substantially quadrilateral.

In one preferred embodiment, the width of the ramp base at an end of the feed ramp is greater than the width of the ramp base at a connection between the feed ramp and the feed chute.

Preferably, an end of the feed ramp is located on a side wall of the hydrocyclone that is opposite to a connection between the feed ramp and the feed chute. In another form, the invention resides in a method of separating different materials using a hydrocyclone separation apparatus including the steps of: passing a slurry through a feed chute to a feed ramp, the feed ramp having a ramp side wall and a ramp base formed at an angle to the ramp side wall; passing the slurry along the feed ramp to the main body of the hydrocyclone separation apparatus; passing the slurry in a spiral path around the main body to a lower body of the hydrocyclone separation apparatus; separating the slurry within the lower body of the hydrocyclone separation apparatus into an overflow stream and an underflow stream; collecting the overflow stream through an overflow outlet; and collecting the underflow stream through an underflow outlet; wherein the angle formed between the ramp side wall and the ramp base varies along a length of the feed ramp.

BRIEF DESCRIPTION OF THE DRAWINGS To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein:

FIG. 1 shows a top view of a hydrocyclone separation apparatus according to an embodiment of the invention; FIGS. 2a-c show perspective side views of the hydrocyclone separation apparatus shown in FIG. 1 ;

FIG. 3 shows a vertical cross sectional plane view through the hydrocyclone separation apparatus shown in FIG. 1 ;

FIG. 4 shows a cross sectional view of the hydrocyclone separation apparatus shown in FIG. 1 ;

FIG. 5 shows a computer-generated simulation of an air core formed in a standard prior art hydrocyclone separation apparatus; and

FIG. 6 shows a computer-generated simulation of an air core formed in a hydrocyclone separation apparatus according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS The invention relates to a hydrocyclone separation apparatus having an inlet section comprising a feed chute and a feed ramp. The feed ramp extends about an inner wall of the inlet section of the hydrocyclone and comprises a ramp wall and a ramp base which forms an angle with the ramp wall. The angle between the ramp wall and the ramp base varies along the length of the feed ramp. This design promotes a laminar flow of feed material which results in less turbulence within the inlet section of the hydrocyclone and a stable air core of more uniform cross section.

FIG. 1 shows a top view of a hydrocyclone separation apparatus 100 according to an embodiment of the invention. FIGS. 2a, 2b and 2c show perspective side views of the hydrocyclone separation apparatus 100, as indicated on FIG. 1.

The hydrocyclone separation apparatus 100 comprises an inlet section 110, a main body 120, a lower body 130 and a lid section 140.

The inlet section 110 is in fluid communication with a feed pipe 200. The feed pipe 200 delivers feed slurry from preceding process steps and is usually of a circular or rounded cross section. The feed pipe 200 is in fluid connection with a feed chute 111 which has a generally rectangular or quadrilateral cross section. The base of the feed chute 111 is planar and has a generally horizontal orientation. The feed chute 111 is in fluid connection with a feed ramp 112.

The feed ramp 112 extends about an inner wall of the main body 120 and comprises a ramp side wall 113 and a ramp base 114 formed at an angle to the ramp side wall 113. The ramp side wall 113 has a vertical orientation and, in the embodiment shown, becomes coplanar with an inner wall of the main body 120 of the hydrocyclone 100 at a point approximately on the opposite side of the hydrocyclone to the point where the feed chute 111 terminates. The point at which the ramp side wall 113 becomes coplanar with an inner wall of the main body 120 may alternatively be at any point on the main body 120 of the hydrocyclone 100, as would be obvious to a person skilled in the field.

The ramp base 114 has a proximal end adjoining the feed chute 111 and a distal end at which point the ramp base 114 terminates and becomes coplanar with an inner wall of the main body 120 of the hydrocyclone 100. The angle formed between the ramp base 114 and the ramp side wall 113 varies along the length of the feed ramp 112. Preferably, the angle formed between the ramp base 114 and the ramp side wall 113 increases along the length of the feed ramp 112. In one embodiment, at the proximal end of the feed ramp 112, the ramp base 114 has a substantially horizontal orientation such that the angle between the ramp side wall 113 and the ramp base 114 is substantially perpendicular. In one embodiment, at the distal end of the feed ramp 112, the angle between the ramp side wall 113 and the ramp base 114 is substantially linear, such that the ramp base 114 has a substantially vertical orientation and is coplanarwith both the ramp side wall 113 and the inner wall of the main body 120 of the hydrocyclone 100.

Preferably, the width of the ramp base 114 increases towards the distal end. Alternatively, the ramp base 114 is of constant width or decreases towards the distal end. The ramp base 114 is joined to the ramp side wall 113, forming a corner, and has a free edge toward the central axis of the hydrocyclone 100. The corner at which the ramp side wall 113 and the ramp base 114 join may be a sharp corner or it may be a rounded corner. Similarly, the free edge of the ramp base 114 may be a sharp edge or a rounded edge.

The main body 120 of the hydrocyclone 100 has a generally cylindrical shape. A lower body 130 is provided that is of a generally frustroconical shape and is coaxial with the main body 120 of the hydrocyclone 100. At the nadir of the lower body 130 an underflow outlet 131 is provided.

The lid section 140 connects to the inlet section 110 and comprises an overflow outlet 141. In one embodiment, the connection between the lid section 140 and the inlet section 110 is such that part of the feed chute 111 is formed by the lid section 140. Alternatively, the connection between the lid section 140 and the inlet section 110 lies above the feed chute 111 , or the inlet section 110 and lid section 140 are manufactured as one piece.

FIG. 3 shows a vertical cross sectional plane view along line A-A', as shown in FIG. 1 , through a hydrocyclone separation apparatus according to one embodiment. The ramp side wall 113 and ramp base 114 may be seen in this cross section plane. The angle of the ramp base 114 to the ramp side wall 113 shown in this section plane is between the substantially perpendicular angle formed at the proximal end of the feed ramp 112 and the substantially linear angle formed at the distal end of the feed ramp 112.

A vortex finder 142 of frustroconical shape, coaxial with the main body 120 of the hydrocyclone 100, extends from the centre of the top of the hydrocyclone 100 into the main body 120, as is well known in the art.

In operation of the hydrocyclone separation apparatus, a feed stream, which may comprise a slurry or liquid feed, enters the inlet section 110 of the hydrocyclone 100 via the feed pipe 200. After passing through the feed chute 111 , the feed travels along the feed ramp 112. The rectangular cross section of the feed chute 111 , together with the gradual change in angle of the ramp base 114 to the ramp wall 113 from perpendicular to linear, serves to promote laminar flow of the feed. After travelling down the feed ramp 112, the feed then enters the main body 120.

Due to the pressure of the feed stream, the shape of the inlet section 110 and gravity, the feed travels down the main body 120 in a spiral path. The feed stream then enters the lower body 130 where the reducing diameter of the lower body 130 creates forces in the stream which causes separation of the feed stream into an overflow stream and an underflow stream. The overflow stream, containing smaller or less dense particles or a less dense liquid, moves to the centre of the hydrocyclone 100 and moves upwards and out through the overflow outlet 141 in the lid section 140. The underflow stream, containing larger or denser particles or a denser liquid, moves to the walls of the lower body 130 and exits the hydrocyclone 100 through the underflow outlet 131 at the nadir of the lower body 130.

Computational fluid dynamic (CFD) studies carried out on examples of the hydrocyclone of the invention have shown that the central air core, which develops during use of a hydrocyclone, has a more uniform diameter in the hydrocyclone of the invention than a hydrocyclone of standard prior art design. FIG. 5 shows the air core of a standard prior art hydrocyclone 300, and it may be seen that the surface of the air core 310 has a non-linear appearance when viewed vertically i.e. small standing waves on the inner surface from the underflow outlet 341 through the lower body section 340 and the main body section 330.

FIG. 6 shows the air core of a hydrocyclone of an embodiment of the invention 100 and it may be seen that, in contrast to FIG. 5, the air core 117 in the inlet section 110 is substantially linear when viewed vertically between the main body 120 and lower body section 130 of the hydrocyclone 100.

It was also found during CFD testwork that the hydrocyclone of the invention had a feed pressure that was substantially lower than the feed pressure of the standard, prior art design. This results in the hydrocyclones of the invention having an increased capacity over hydrocyclones of standard design.

The inlet section design of the hydrocyclone of the invention introduces the feed stream to the hydrocyclone with reduced turbulence when compared to prior art hydrocyclone separation apparatus. This will likely result in an air core of greater stability which may lead to a more efficient separation, higher capacity and throughput rates. Equipment lifetimes are likely to be lengthened and down time reduced due to less uneven wear.

Throughout the specification the aim has been to describe the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the invention. For example, the hydrocyclone may be manufactured as a single unit, rather than in sections that are connected together. It will be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.

Claims

Claims:

1. A hydrocyclone separation apparatus comprising: a feed chute; and a feed ramp in fluid communication with the feed chute, the feed ramp having a ramp side wall and a ramp base formed at an angle to the ramp side wall; wherein the angle formed between the ramp side wall and the ramp base varies along a length of the feed ramp.

2. The hydrocyclone separation apparatus of claim 1 , wherein at a point along the length of the feed ramp, the ramp base is substantially co-planar with an inner wall of a main body of the hydrocyclone separation apparatus.

3. The hydrocyclone separation apparatus of claim 1 , wherein the angle between the ramp side wall and the ramp base increases along the length of the feed ramp.

4. The hydrocyclone separation apparatus of claim 1 , wherein the angle between the ramp side wall and the ramp base varies along the length of the feed ramp from substantially perpendicular to substantially linear.

5. The hydrocyclone separation apparatus of claim 1 , wherein the ramp base varies along the length of the feed ramp from being in a horizontal orientation to a vertical orientation.

6. The hydrocyclone separation apparatus of claim 1 , wherein the base of the feed chute is planar.

7. The hydrocyclone separation apparatus of claim 1 , wherein the cross sectional shape of the feed chute is substantially quadrilateral.

8. The hydrocyclone separation apparatus of claim 1 , wherein the width of the ramp base is constant along the length of the feed ramp.

9. The hydrocyclone separation apparatus of claim 1 , wherein the width of the ramp base at an end of the feed ramp is greater than the width of the ramp base at a connection between the feed ramp and the feed chute.

10. The hydrocyclone separation apparatus of claim 1 , wherein an end of the feed ramp is located on a side wall of the hydrocyclone that is opposite to a connection between the feed ramp and the feed chute.

11. The hydrocyclone separation apparatus of claim 1 , wherein the feed ramp traverses substantially 180° of a circumference of the main body of the hydrocyclone separation apparatus.

12. A method of separating different materials using a hydrocyclone separation apparatus including the steps of: passing a slurry through a feed chute to a feed ramp, the feed ramp having a ramp side wall and a ramp base formed at an angle to the ramp side wall; passing the slurry along the feed ramp to the main body of the hydrocyclone separation apparatus; passing the slurry in a spiral path around the main body to a lower body of the hydrocyclone separation apparatus; separating the slurry within the lower body of the hydrocyclone separation apparatus into an overflow stream and an underflow stream; collecting the overflow stream through an overflow outlet; and collecting the underflow stream through an underflow outlet; wherein the angle formed between the ramp side wall and the ramp base varies along a length of the feed ramp.

13. The method of claim 12, wherein at a point along the length of the feed ramp, the ramp base is substantially co-planar with an inner wall of a main body of the hydrocyclone separation apparatus.

14. The method of claim 12, wherein the angle between the ramp side wall and the ramp base increases along the length of the feed ramp.

15. The method of claim 12, wherein the angle between the ramp side wall and the ramp base varies along the length of the feed ramp from substantially perpendicular to substantially linear.

16. The method of claim 12, wherein the ramp base varies along the length of the feed ramp from being in a horizontal orientation to a vertical orientation.

17. The method of claim 12, wherein the base of the feed chute is planar.

18. The method of claim 12, wherein the cross sectional shape of the feed chute is substantially quadrilateral.

19. The method of claim 12, wherein the width of the ramp base at an end of the feed ramp is greater than the width of the ramp base at a connection between the feed ramp and the feed chute.

20. The method of claim 12, wherein an end of the feed ramp is located on a side wall of the hydrocyclone that is opposite to a connection between the feed ramp and the feed chute.