ZA200909122B - Bulk material transfer - Google Patents
Bulk material transfer Download PDFInfo
- Publication number
- ZA200909122B ZA200909122B ZA200909122A ZA200909122A ZA200909122B ZA 200909122 B ZA200909122 B ZA 200909122B ZA 200909122 A ZA200909122 A ZA 200909122A ZA 200909122 A ZA200909122 A ZA 200909122A ZA 200909122 B ZA200909122 B ZA 200909122B
- Authority
- ZA
- South Africa
- Prior art keywords
- bulk material
- rotation
- mouth
- radially inner
- rotatable
- Prior art date
Links
- 239000013590 bulk material Substances 0.000 title claims description 94
- 239000000463 material Substances 0.000 claims description 51
- 238000000034 method Methods 0.000 claims description 27
- 238000009434 installation Methods 0.000 claims description 16
- 230000005484 gravity Effects 0.000 claims description 13
- 230000003116 impacting effect Effects 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 230000000977 initiatory effect Effects 0.000 claims description 3
- 241000087826 Orapa Species 0.000 claims 1
- 239000000428 dust Substances 0.000 description 4
- 239000013072 incoming material Substances 0.000 description 4
- 238000005297 material degradation process Methods 0.000 description 2
- 239000011236 particulate material Substances 0.000 description 1
- 230000000284 resting effect Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
Landscapes
- Chutes (AREA)
Description
y : WI ~200076
I 2 "2009709122 .
THIS INVENTION relates to bulk material transfer from conveyance devices such as conveyors, chutes or the like. In particular, the invention relates to a bulk material transfer device, to a bulk material conveyance installation and to a method of transferring bulk material from a bulk material conveyance device.
It is often required to transfer material being conveyed from one conveyance device, e.g. a conveyor or chute or the like, under gravity onto another conveyance device, or into a process unit such as a storage device, bin, silo, mill, drier or the like. Conventionally, a chute is used to perform the transfer. Depending on the material being conveyed, the chute may be subject to wear, and the material may be degraded and may generate dust, particularly when the material is to be transferred from a high speed conveyance device. It would be desirable if the abovementioned disadvantages can be avoided, or at least reduced, when material is transferred from a conveyance device, and in particular a high speed conveyance device. ’ According to one aspect of the invention, there is provided a bulk material transfer device for transferring material under gravity from a bulk conveyance device, the transfer device including a body defining a transfer passage with an upper mouth to receive material and a lower mouth to discharge material, at least an upper portion of the body defining said upper mouth being rotatable about an axis of rotation extending through the upper mouth.
Typically, the body, or at least said upper portion thereof, is a body of revolution, with a circular upper mouth and with said axis of rotation extending through the upper mouth. Preferably, the axis of rotation extends centrally through the upper mouth.
Preferably, the lower mouth is also circular. A lower portion of the body may also be a body of revolution. Preferably, the axis of rotation extends centrally
"through both the upper mouth and the lower mouth. The axis of rotation is upwardly " extending, typically but not necessarily always being vertical.
A portion of the body defining the lower mouth may be tapered, e.g. in the form of an inverted frusto-cone. Preferably, said portion of the body defining the lower mouth is not rotatable, in use being stationary relative to the axis of rotation of the upper portion, with said upper portion of the body defining the upper mouth in use rotating about the axis of rotation.
The transfer device may include a force transfer arrangement to transfer a driving force to the rotatable portion of the body in use to rotate the rotatable portion. In principle, many embodiments of such a force transfer arrangement can be used, e.g. a drive wheel, a chain drive, a belt drive, a ring or planetary gear and pinion gear arrangement, a drive shaft, and the like.
The transfer device may include a drive, e.g. an electric motor, operatively connected to the force transfer arrangement in use to rotate the rotatable portion of the body. The drive may be disconnectable from the force transfer arrangement, e.g. via a clutch.
The transfer device may include a spillage chute extending from an area adjacent the upper mouth but outside the body into the body, below the rotatable portion of the body.
The drive may be capable of rotating the rotatable portion of the body such that, in use, an annular radially interior zone of the rotatable portion of the body being impacted by material received through the upper mouth rotates at a tangential or linear velocity of between 2.5 m/s and 25 m/s, typically between 5 m/s and 15 m/s.
Advantageously, this allows matching a tangential velocity of said zone of the rotatable portion of the body with the linear velocity of impacting material.
According to another aspect of the invention, there is provided a bulk material conveyance installation which includes a bulk material conveyance device having a discharge end; and
* ) . : {of -. 4 | =2009 /09 122 a bulk material transfer device arranged to receive material from the discharge end of the bulk material conveyance device and to transfer the material under gravity, the material transfer device including a body defining a transfer passage with an upper mouth to receive material from the discharge end of the bulk material conveyance device and a lower mouth to discharge said material, at least an upper portion of the body defining said upper mouth being rotatable about an axis of rotation extending through the upper mouth.
The bulk material transfer device may be as hereinbefore described.
In one embodiment of the invention, the bulk material conveyance device is a mechanical conveyance device, e.g. a high speed conveyor. In another embodiment of the invention, the bulk material conveyance device is a gravity-operated device, e.g. an inclined chute or trough or pipe or the like.
A portion of the body, arranged in use to be impacted by material discharged from the discharge end of the bulk material conveyance device, may define a cylindrical or-annular radially inner surface. The bulk material conveyance device may be arranged to discharge material at its discharge end in a stream, in a direction which is for a centre line of said stream, at an angle to a tangent to said cylindrical inner surface at a point of impact of the centre line on said inner surface, of less than 70°, preferably less than 60°, more preferably less than 50, e.g. between about 30° and about 50°.
In other words, the angle of incidence of said centre line of discharged material to the circular cylindrical inner surface may be less than 70°, preferably less than 60°, more preferably less than 50°, e.g. between about 30° and about 50°.
The bulk material conveyance device may be operable to discharge material at its discharge end at a linear velocity of between about 2.5 m/s and about 25 m/s, typically between about 5 m/s and about 15 m/s.
' \ } According to a further aspect of the invention, there is provided a method ~ of transferring bulk material from a bulk material conveyance device, the method including discharging the bulk material from the bulk material conveyance device against a radially inner surface of a rotating body rotating about an upwardly extending axis of rotation; and allowing the bulk material to drop under gravity from the rotating body.
The bulk material conveyance device may be as hereinbefore described.
The rotating body may form part of a bulk material transfer device as hereinbefore described. In particular, the rotating body may be said upper portion of the transfer passage-defining body of said bulk material transfer device. : | The method may include initiating rotation of a rotatable body to provide said rotating body, prior to discharging the bulk material from the bulk material conveyance device against said radially inner surface. This may be effected by applying an external force to the rotatable body. The method may include removing said external force once the bulk material has begun being discharged against said radially inner surface, and maintaining rotation of the rotating body by using the momentum of the bulk material being discharged against said radially inner surface.
Typically, the bulk material is discharged in a stream which has a centre line with an angle of incidence to the radially inner surface of less than 70°, preferably less than 60°, more preferably less than 50°, e.g. between about 30° and about 50° .
The method may include allowing the bulk material to drop under gravity from the rotating body through a non-rotating body, and discharging the bulk material from the non-rotating body. The non-rotating body may be the portion of the body of the bulk material transfer device defining the lower mouth, as hereinbefore described.
The method may include rotating the rotating body at an angular velocity sufficiently high to allow a layer of bulk material discharged against the rotating radially inner surface to build up due to centrifugal force, said layer being thick enough and
- | Co J : \ !
B 009709122 3 . ] extending over a sufficiently large axially extending portion of the radially inner surface to protect said radially inner surface .against impacting bulk material so that the impacting bulk material impacts said layer and not the radially inner surface.
The method may include allowing said layer of bulk material to build up horizontally to a degree where the radius of rotation of radially innermost particles reduce to such an extent that gravitational force becomes more dominant than the centrifugal force which allows the particles to be supported on the vertical or upwardly extending cylindrical layer of material, with the radially innermost bulk material thus dropping under gravity from the cylindrical layer of material. This radius of rotation is material dependant and will therefore vary as will an exit tangential velocity of the particles. This exit tangential velocity is preferably less than 4 m/s, more preferably less than 3 m/s. 16 The method may include catching bulk material escaping from the bulk material conveyance device adjacent but external the rotating body, and guiding said escaped material into the non-rotating body.
The method may include directing the flow of the bulk material by means of a diverter from the bulk material conveyance device into said upper mouth of the body of the transfer device. This method of guiding the bulk material into the transfer device is of particular importance when the speed of the incoming bulk material being fed to the bulk material transfer device is such that its natural trajectory when subjected to gravity does not permit the material to enter the transfer device in an acceptable manner.
The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which
Figure 1 shows a three-dimensional view of a bulk material conveyance installation in accordance with the invention, which includes a bulk material transfer device in accordance with the invention;
Figure 2 shows a side view of the installation of Figure 1;
Figure 3 shows a plan view of the installation of Figure 1, with parts omitted for clarity; and :
‘ |]
FR
RE . 2009709129
Figure 4 shows a vertical section, taken at IV-IV in Figure 3, of the installation of * Figure 1 in use. : Referring to the drawings, reference numeral 10 generally indicates a bulk - material conveyance installation in accordance with the invention. The installation 10 includes a bulk material conveyance device in the form of a high speed conveyor 12 comprising a conveyor belt 14 and a head pulley 16 at a discharge end of the conveyor 12.
The bulk material conveyance installation 10 further includes a bulk material transfer device 18 in accordance with the invention. The bulk material transfer device 18 includes a frame 20 supporting a body of revolution 22 defining a transfer passage with a circular upper mouth 26 and a circular lower mouth 28 and an axis of rotation 30 extending vertically through both the upper mouth 26 and the lower mouth 28.
The body 22 comprises an upper body portion 22.1 and a lower body portion 22.2. The lower body portion 22.2 is in the form of an inverted frusto-cone and is fixed to a lower platform 32 of the frame 20, the platform 32 resting on four legs 34. ‘The lower body portion 22.2 has a plurality of circumferentially spaced upwardly extending external strengthening ribs 36. The lower body portion 22.2 in use does not rotate about the axis of rotation 30, being stationery relative to the axis of rotation 30.
The upper body portion 22.1 is circular cylindrical and is supported by a platform or structure 38, between the lower platform 32 and the upper platform or structure 38. A plurality of circumferentially spaced carrier wheels 40 support and/or centre the upper body portion 22.1, allowing the upper body portion 22.1 to rotate about the axis of rotation 30. An upper ring of slanted carrier wheels 40 supports the upper body portion 22.1 in suspended fashion below the upper platform 38. Further carrier wheels 40 arranged in two vertically spaced rings below the upper ring centre the upper body portion 22.1 about the axis of rotation 30.
The upper body portion 22.1 includes an external annular ladder frame 42 for stiffness.
} A force transfer arrangement, in the form of a drive wheel 44 mounted to the frame 20 engages one of the carrier wheels 40 in use to transfer a driving force from a drive, e.g. an electric motor (not shown), via the carrier wheel 40 against which the drive wheel 44 bears, to the upper body portion 22.1 to rotate the upper body portion 22.1 about the axis of rotation 30.
A spillage chute 46 extends from below the head pulley 16 to the lower body portion 22.2 and opens out into the lower body portion 22.2. :
The conveyor 12 includes a discharge chute 48 extending from immediately adjacent the conveyor belt 14 where it runs around the head pulley 16, over a rim of the upper mouth 26, into the upper body portion 22.1. The discharge chute 48 extends in a plane parallel to a plane which is tangential to the upper body porion22.1. oo
A diverter 50 is provided over the discharge chute 48 and a cover 52 is provided over the upper body portion 22.1. :
In use, the high speed conveyor 12 discharges bulk material from the conveyor belt 14 over and through the discharge chute 48 into the upper body portion 22.1. The high speed conveyor 12 has a linear conveyor belt speed of at least 5 m/s.
Before material is discharged from the conveyor belt 14 into the upper body portion : 22.1, rotation of the upper body portion 22.1 about the axis of rotation in the direction of arrow 54 (see Figure 3) is initiated by means of the drive, drive wheel 44 and carrier wheel 40 against which the drive wheel 44 bears. A tangential velocity of the upper body portion 22.1 is matched to the linear velocity of the conveyor belt 14 and the bulk material is then fed by means of the conveyor belt 14 into the upper body portion 22.1.
As will be appreciated, as a result of the discharged material impacting a circular cylindrical, radially interior surface or zone of the upper body portion 22.1 non- perpendicularly, a rotational force will be imparted to the upper body portion 22.1. If this rotational force is sufficient to maintain rotation of the upper body portion 22.1, the drive may be disengaged from the drive wheel 44, or the drive wheel 44 may be disengaged from the carrier wheel 40 against which it bears, and the drive may be stopped. If
~ | 9 2009/09 122 _ sufficient rotational force is not transferred to the upper body portion 22.1 by the "impacting material, the drive is used to maintain rotation of the upper body portion 22.1 at the desired angular velocity.
Any particulate material which spills from the conveyor belt 14 at the head pulley 16, is caught by the spillage chute 46 and transferred into the lower body portion 22.2.
As shown in Figure 3 of the drawings, the bulk material is discharged from the conveyor belt 14 in a stream which has an angle of incidence a to the radially inner surface of the upper body portion 22.1 of less than 70°, preferably less than 60°, more preferably less than 50°, e.g. between about 30° and about 50° or between about 40° and about 50°. | ‘The ‘upper body portion 22.1, in matching angular velocity to the linear velocity of bulk material discharged into the upper body portion 22.1, rotates at a sufficiently high angular velocity to allow a layer 56 of bulk material discharged against the rotating radially inner surface to build up due to centrifugal force. As can be seen in
Figure 4, this layer 56 is thick enough and extends over a sufficiently large axially extending portion of the radially inner surface to protect the radially inner surface against impacting bulk material. As will be appreciated, this layer builds up to a point where material falls from the layer due to gravitational force having become more dominant than centrifugal force. The material falls into the lower body portion 22.2 and at that point typically has a tangential exit velocity of less than 5 m/s, preferably less than 4m/s, more preferably less than 3m/s. However this varies from bulk material to bulk material. By means of the bulk material transfer device 18, bulk material is thus transferred from the high speed conveyor 12, under gravity, through the rotating upper body portion 22.1 and the stationary lower body portion 22.2, to be discharged through the lower mouth 28, into any desired location or process equipment or onto any desired process equipment, e.g. a further conveyor.
Advantageously, the bulk material transfer device 18, as illustrated, can function as a low-wearing transfer chute to transfer material from one or more high speed conveyors to another high speed conveyor, or from one or more high speed
NN
{ ® 1) . - 0 : 2009 709122 ~ conveyors to a slower conveyor, or from one or more high speed conveyors to a piece of process equipment, such as a storage facility, or onto a stock pile. Advantageously, the bulk material transfer device 18 is subject to reduced chute wear, material degradation and dust generation. This is achieved by matching the tangential velocity of the upper body portion 22.1 to that of the incoming material being discharged into the upper body portion 22.1 as closely as possible in a cost-effective way.
As described above, in use, material entering the upper body portion 22.1, due to the angular velocity of the upper body portion 22.1 and associated centrifugal forces, initially remains suspended on the vertical radially interior surface of the upper body portion 22.1. As more material is added a vertically extending bed or layer of material is formed. The bed depth builds up horizontally to a point where the radius of rotation becomes reduced, thus reducing the outward centrifugal forces to a point where gravity becomes dominant and material falls down into the inverted frusto-cone of the | lower body portion 22.2, before being discharged out of the lower mouth 28.
Advantageously, with the bed of material held against the radially interior surface of the upper body portion 22.1 by centrifugal forces, the upper body portion 22.1 is protected against incoming material as impact is predominantly material on material. As a result of low or no relative velocities between the bed of material and the incoming material, and as a result of a relatively small angle of incidence where the incoming material stream impacts against the bed of material, material degradation is inhibited. Should dust control be an issue, the bulk material transfer device 18 lends itself well to the installation of a hood structure over the upper body portion 22.1 with extracted dust being recycled back into the body of revolution 22, or being extracted completely.
Claims (24)
1. A bulk material transfer device for transferring material under gravity from a bulk conveyance device, the transfer device including a body defining a transfer passage with an upper mouth to receive material and a lower mouth to discharge material, at least an upper portion of the body defining said upper mouth being rotatable about an axis of rotation extending through the upper mouth.
2. The device as claimed in claim 1, in which the body, or at least said upper portion thereof, is a body of revolution, with a circular upper mouth and with said axis of rotation extending through the upper mouth. ©
3 The device as claimed in claim 1 or claim 2, in which the axis of rotation extends centrally through the upper mouth.
4, The device as claimed in any of claims 1 to 3, in which the lower mouth is circular, with a lower portion of the body being a body of revolution, and with the axis of rotation extending centrally through both the upper mouth and the lower mouth.
5. The device as claimed in any of claims 1 to 4, in which a portion of the body defining the lower mouth is not rotatable, in use being stationary relative to the axis of rotation, with said upper portion of the body defining the upper mouth in use rotating about the axis of rotation.
6. The device as claimed in any of claims 1 to 5, which includes a force transfer arrangement to transfer a driving force to the rotatable portion of the body in ~ useto rotate the rotatable portion.
7. The device as claimed in claim 5, which includes a spillage chute extending from an area adjacent the upper mouth but outside the body into the body, below the rotatable portion of the body.
- 8. A bulk material conveyance installation which includes a bulk material conveyance device having a discharge end; and a bulk material transfer device arranged to receive material from the discharge end of the bulk material conveyance device and to transfer the material under gravity, the material transfer device including a body defining a transfer passage with an upper mouth to receive material from the discharge end of the bulk material conveyance device and a lower mouth to discharge said material, at least an upper portion of the body defining said upper mouth being rotatable about an axis of rotation extending through the upper mouth.
9. The installation as claimed in claim 8, in which the bulk material transfer device is a device as claimed in any of claims 1 to 7.
10. The installation as claimed in claim 8 or claim 9, in which a portion of the body, arranged in use to be impacted by material discharged from the discharge end of the bulk material conveyance device, defines a cylindrical or annular radially inner surface, the bulk material conveyance device being arranged to discharge material at its discharge end in a stream, in a direction which is for a centre line of said stream, at an angle to a tangent to said cylindrical inner surface at a point of impact of the centre line on said inner surface, of less than 70°. :
11. The installation as claimed in claim 10, in which said angle is less than
60°. :
12. The installation as claimed in claim 11, in which said angle is between 30° and 50°.
13. A method of transferring bulk material from a bulk material conveyance
30 . device, the method including discharging the bulk material from the bulk material conveyance device against a radially inner surface of a rotating body rotating about an upwardly extending axis of rotation; and allowing the bulk material to drop under gravity from the rotating body.
oo 13
14. The method as claimed in claim 13, in which the rotating body forms part of a bulk material transfer device as claimed in any of claims 1 to 7.
15. The method as claimed in claim 13 or claim 14, which includes initiating rotation of a rotatable body to provide said rotating body, prior to discharging the bulk material from the bulk material conveyance device against said radially inner surface.
16. The method as claimed in claim 15, in which initiating rotation of a rotatable body is effected by applying an external force to the rotatable body, the method including removing said external force once the bulk material has begun being discharged against said radially inner surface, and maintaining rotation of the rotating body by using the momentum of the bulk material being discharged against said radially inner surface.
17. The method as claimed in any of claims 13 to 16, in which the bulk material is discharged in a stream which has a centre line with an angle of incidence to the radially inner surface of less than 70°. :
18. The method as claimed in claim 17, in which the angle of incidence is less than 60°. : :
19. The method as claimed in claim 18, in which the angle of incidence is between 30° and 50°.
25 .
20. The method as claimed in any of claims 13 to 19, which includes rotating the rotating body at an angular velocity sufficiently high to allow a layer of bulk material discharged against the rotating radially inner surface to build up due to centrifugal force, said layer being thick enough and extending over a sufficiently large axially extending portion of the radially inner surface to protect said radially inner surface against impacting bulk material so that the impacting bulk material impacts said layer and not the radially inner surface.
- 21. The method as claimed in claim 20, which includes allowing said layer of bulk material to build up horizontally to a degree where the radius of rotation of radially innermost particles reduce to such an extent that gravitational force becomes more dominant than the centrifugal force which allows the particles to be supported on the vertical or upwardly extending cylindrical layer of material, with the radially innermost bulk material thus dropping under gravity from the cylindrical layer of material.
22. A bulk material transfer device as claimed in claim 1, substantially as herein described with reference to and as illustrated in any of the drawings.
23. A bulk material conveyance installation as claimed in claim 8, substantially as herein described with reference to and as illustrated in any of the drawings.
24, A method of transferring bulk material as claimed in claim 13, substantially as herein described with reference to and as illustrated in any of the drawings. Dated this 21° day of December 2009 DAMS & ADAMS APPLICANTS’ PATENT ATTORNEYS
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA200909122A ZA200909122B (en) | 2009-04-15 | 2009-12-21 | Bulk material transfer |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA200902591 | 2009-04-15 | ||
| ZA200909122A ZA200909122B (en) | 2009-04-15 | 2009-12-21 | Bulk material transfer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| ZA200909122B true ZA200909122B (en) | 2010-09-29 |
Family
ID=43618574
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| ZA200909122A ZA200909122B (en) | 2009-04-15 | 2009-12-21 | Bulk material transfer |
Country Status (1)
| Country | Link |
|---|---|
| ZA (1) | ZA200909122B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8016912B2 (en) | 2007-09-14 | 2011-09-13 | Barrick Gold Corporation | Process for recovering platinum group metals using reductants |
-
2009
- 2009-12-21 ZA ZA200909122A patent/ZA200909122B/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8016912B2 (en) | 2007-09-14 | 2011-09-13 | Barrick Gold Corporation | Process for recovering platinum group metals using reductants |
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