Patent Grant
10537895
This application is a § 371 National Stage Application of PCT International Application No. PCT/EP2014/060512 filed May 22, 20154 claiming priority of EP Application No. 13174042.5, filed Jun. 27, 2014.
The present invention relates to a gyratory crusher annular crushing shell and in particular, although not exclusively to a series of axially extending wedges that project radially at a crushing surface of the shell, the wedges being spaced apart around the axis with material flow channels defined by and positioned between each of the wedges.
Gyratory crushers are used for crushing ore, mineral and rock material to smaller sizes. Typically, the crusher comprises a crushing head mounted upon an elongate main shaft. A first crushing shell (typically referred to as a mantle) is mounted on the crushing head and a second crushing shell (typically referred to as a concave) is mounted on a frame such that the first and second crushing shells define together a crushing chamber through which the material to be crushed is passed. A driving device positioned at a lower region of the main shaft is configured to rotate an eccentric assembly positioned about the shaft to cause the crushing head to perform a gyratory pendulum movement and crush the material introduced in the crushing chamber. Example gyratory crushers are described in WO 2004/110626; WO 2008/140375, WO 2010/123431 and WO 2012/005651.
Primary crushers are heavy-duty machines designed to process large material sizes of the order of one meter. Secondary and tertiary crushers are however intended to process relatively smaller feed materials typically of a size less than fifty centimetres. Cone crushers represent a sub-category of gyratory crushers and may be utilised as downstream for final processing of materials. However, common to all types of gyratory crushers is a requirement to crush the material according to a predetermined reduction an as to obtain a desired particulate size of material exiting the crusher. WO 2006/101432 discloses an inner crushing shell having a series of raised crushing surfaces that project radially from the outward facing surface of the shell wall that are configured to provide a variable gap distance between the outer crushing shell to accommodate and crush a range of different sized pieces of material within the crushing zone.
One of the most common user demands on gyratory crushers is high reduction. Reduction is however restricted by limitations of energy consumption (power draw) and hydraulic pressure which are both related to the crushing force. Crushing dynamics principally involve the material pieces being trapped, compressed and then crushed in the zone between the mantle and the concave as they fall through the crusher. The crushing process is complex and the performance of the crusher is determined by a number of factors including i) the size distribution of material as it enters the crusher ii) the dynamics of the material as it is crushed and breaks; iii) the machine operating parameters including for example the close side setting (CSS), open side setting (OSS), stroke and speed and iv) the geometry of the machine and the crushing zone including in particular the gap between the concave and the mantle in to which the material falls.
One problem with existing crushers is the undesirable frequency with which the crusher ‘chokes’. This occurs as the crusher allows entry of more material than what can be crushed in the lower crushing zones (below the choke point) due to limitation in the available crushing force. A result of this choking is that the force is insufficient to crush the material in the gap and the crusher can no longer retain the CSS. The crusher must then open, typically an automated process, to allow the choked material to exit the crusher and the crusher effectively reset. What is required is a gyratory crusher that addresses these problems and the disruption caused by choking.
It is an objective of the present invention to provide a gyratory crusher and at least one crushing shell being optimised to control the choke zones within the crushing chamber and to provide a crusher having a balanced capacity with increased reduction potential. It is a further objective to provide a gyratory crusher to control the flow of material passing through the crushing zone to allow the crusher to be operated at reduced close side setting (CSS) without increasing the crushing force. It is a further objective of the present invention to increase and optimise the crushing capacity of the entire crushing process particularly where a gyratory crusher is operated in a closed crushing circuit (being coupled to a downstream screen) by generating consistently crushed material having a particle or piece size within a predetermined reduction range.
The objectives are achieved by providing a crushing shell having a plurality of wedges that project radially at the shell crushing surface. The wedges are spaced apart in a circumferential direction around a central longitudinal axis (around which the shell extends) such that channels are created between the wedges at the crushing surface. The wedges act to direct the material flow into channels (that extend between the wedges) so as to control the flow of material passing through the crushing zone between the opposed inner and outer crushing shells. According to one aspect, the wedges are provided at only one of the inner or outer crushing shells. However, according to further embodiments, the wedges may be provided at both the inner and outer crushing shells.
The wedges are positioned at an axially upper region of the shell so as to extend axially downward along the body of the shell and to decrease in radial extension in the axially downward direction such that the wedges do not continue to the axially lower regions of the crushing surface. Accordingly, the wedges are intended to control the flow of material into the axially lower crushing zones between the inner and outer crushing shells. The wedges effectively decrease the overall volume within a ‘choke zone’ and this serves to raise the position of the choke zone axially upward in the crushing chamber. The wedges are further advantageous to reduce the amount of material being processed in the crushing chamber and to allow the crusher to be operated at a smaller CSS without a requirement to increase the crushing force. Accordingly, the reduction level of the crusher is increased together with the process capacity as the need to ‘open’ the crushing zone (typically via hydraulic rams) is avoided as the crusher does not experience choking as with conventional crushers.
According to a first aspect of the present invention there is provided a gyratory crusher crushing shell comprising: a main body mountable within a crushing zone defined by a frame of a gyratory crusher, the main body extending around a central longitudinal axis; the main body having a mount surface for positioning opposed to the frame or a crusher head movably mounted within the crushing zone and a crushing surface to contact material to be crushed, a wall defined by and extending between the mount and crushing surfaces, the wall having an axially upper first end and an axially lower second end; a plurality of wedges projecting radially at the crushing surface and distributed in the circumferential direction around the axis, each wedge extending axially downward from a region of the first end; characterised in that: each wedge is terminated in the circumferential direction by a pair of lengthwise shoulders; the shell further comprising a plurality of axially extending channels defined by and positioned in the circumferential direction between the shoulders of opposed wedges.
Accordingly, the radial distance of the crushing surface relative to a central axis of the shell increases and decreases according to an alternating profile in a circumferential direction around the axis at an axial position of the wedges and channels. The circumferentially extending alternating profile of the crushing surface at the axially upper region of the shell is effective to control the volume of material that is fed to be axially lower crushing region (between the opposed inner and outer crushing shells). That is, the radially extended shell walls at the region of the wedges feed material into the channels to effectively raise axially the choke point of the crushing zone. This is advantageous to avoid undesirable and premature choking of the crusher. The decreased area function (due to the presence of the wedges) within the crushing zone is effective to allow for a greater reduction whilst maintaining and optimising the particle size distribution exiting the crusher. Accordingly, the need to ‘open’ the crushing zone to purge the crusher is avoided.
Preferably, the wedges extend axially downward from a region substantially at or immediately below the first end. Preferably, the wedges extend axially to a region substantially halfway between the first and second ends or above the halfway region. Accordingly, an axially lower region, and optionally an axially lower half of the crushing shell, is devoid of wedges and channels. This provides that the lower region of the crushing zone is optimised for crushing material according to the CSS.
Optionally, each of the wedges may comprise a radial thickness that decreases in a direction from the first end to the second end. Optionally, the shell wall may comprise a radial thickness that decreases at a region of each wedge in the axial direction from the region of the first end to the second end. Preferably, the shell wall comprises a radial thickness that is substantially uniform at the region of each wedge in the axial direction from the region of the first end to the second end. This is advantageous to provide a uniform cooling rate at the shell wall which in turn eliminates or reduces porosity of the cast material. Preferably, a radial distance between the crushing surface of each wedge and the crushing surface of each channel decreases in an axially downward direction from the region of the first end to the second end.
Preferably, each of the wedges comprise a tapered shape profile in the axial direction such that a radial extension of the wall at a region of each wedge is greater at an axially upper region of each wedge than an axially lower region of each wedge relative to the central axis. This reducing tapered radial extension of the wedge from the central axis (and importantly each neighbouring channel) provides a smooth transition for material flowing from the axially upper to the axially lower crushing zones. Optionally, the crushing surface at the region of each wedge comprises a concave shape profile in the axial direction. That is, the effective difference in the radial extension of the wedge crushing surface relative to the radial position of the crushing surface at each channel decreases to zero so as to provide a smooth transition onto the axially lower crushing surface.
Preferably, a radial thickness of each wedge, or a radial thickness of the wall at the region of each wedge is substantially uniform in a circumferential direction between the shoulders. Optionally, a radial thickness of each channel, or a radial thickness of the wall at the region of each channel is substantially uniform in a circumferential direction between the shoulders.
The shoulders of each wedge may be defined as the radially extending surfaces that terminate each circumferential end of the crushing surface at the region of each wedge. That is, the shoulders may be considered to comprise the end faces of each wedge that define the intermediate channels that are radially recessed relative to the wedges.
According to the preferred embodiment, the shoulders (end surfaces) of each wedge, that define each channel, are substantially uniform in shape and configuration such that each lengthwise edge of each wedge, and therefore each channel, is substantially identical. In particular, the tapered profile of each side surface of each wedge, at each side of each wedge, is substantially the same or identical. Accordingly, each channel is defined and bordered by a side surface of each wedge that is substantially the same or identical. Preferably, each shoulder comprises a pair of axially extending lengthwise side surfaces, each side surface having a tapered shape profile in the circumferential direction to provide a smooth transition with a respective channel. The tapered shape profile of the lengthwise side surfaces of each wedge is configured to provide a smooth transition for material flow from the surface of the wedge into the intermediate channel for the subsequent controlled feed to the lower crushing zone. Preferably, the sides (or shoulders) of the wedges are also tapered in the axial direction so as to decrease to zero at approximately the mid-region between the upper and lower ends of the shell.
Optionally, a width of each channel in the circumferential direction around the axis is substantially equal to a width of each wedge in the circumferential direction around the axis. Optionally, a width of each wedge in a circumferential direction around the axis and between the shoulders increases in the axial direction from the first to the second end. Optionally, a width of each wedge in a circumferential direction around the axis and between the shoulders is substantially uniform along the axial length of the wedge in a direction from the first to the second end. Optionally, a width of each channel in a circumferential direction around the axis is substantially equal to a width of each wedge in a circumferential direction around the axis at the same axial position.
Optionally, the shell comprises between two to ten, three to ten, three to eight or three to six wedges distributed circumferentially around the axis. Optionally, the shell comprises 3, 4, 5, 6 or 7 wedges distributed circumferentially around the axis.
According to one aspect of the present invention, the shell is an outer crushing shell for positioning opposed to the frame such that the wedges are provided at a radially inward facing surface of the shell. According to a further aspect of the present invention the shell is an inner crushing shell for positioning opposed to the crushing head and the wedges are provided at a radially outward facing surface of the shell.
According to a further aspect of the present invention there is provided a gyratory crusher comprising at least one crushing shell as claimed herein.
A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:
Referring to
A drive (not shown) is coupled to main shaft 107 via a drive shaft 108 and suitable gearing 131 so as to rotate shaft 107 eccentrically about longitudinal axis 115 and to cause head 103 to perform a gyratory pendulum movement and crush material introduced into crushing zone 104. An upper end region 128 of shaft 107 is maintained in an axially rotatable position by a top-end bearing assembly 112 positioned intermediate between main shaft 107 and a central boss. Similarly, a bottom end 129 of shaft 107 is supported by a bottom-end bearing assembly 130. Upper frame 101 is divided into a topshell 111, mounted upon lower frame 102 (alternatively termed a bottom shell), and a spider assembly 113 that extends from topshell 111 and represents an upper portion of the crusher.
Shell 106 comprises an annular upper end 121 and opposed lower annular end 122 with a wall 110 extending axially between ends 121, 122. Shell 106 further comprises a radially outward facing mount surface 132 and an opposed radially inward facing crushing surface 125. Similarly, inner crushing shell 105 comprises a radially outward facing crushing surface 117 and an opposed radially inward facing mount surface 118. Crushing zone 104 is defined between the crushing surface 125, 117 of the opposed shells 106, 105 respectively. Outer shell 106 further comprises a first raised upper contact region 126 and a second raised lower contact region 124, the contact regions 126, 124 projecting radially outward from the wall 110 of shell 106 so as to be axially separated and define an annular channel 123 extending circumferentially around shell 106 between upper and lower regions 126, 124. Shell 106 is configured to contact the spacer ring 114 at regions 126, 124.
Similarly, inner shell 105 comprises an annular upper end 119 and an opposed annular lower end 120 with a wall 116 extending axially between ends 119, 120. Shell 105 is mounted at head 103 via contact with an axially lower region of mount surface 118 that is seated upon a radially outward facing surface 133 of head 103.
Shell 105 further comprises a plurality of wedges 127 that projects radially outward from wall 116 to represent raised ridges at the crushing surface 117. Wedges 127 project radially into crushing zone 104 from crushing surface 117 so as to reduce the volume of the crushing zone 104 at an axially upper region of shell 105 and 106. As illustrated in
According to the specific implementation, a radial thickness of each wedge 127 is greatest at its axially uppermost region corresponding to an axial position at edge 209. The ‘radial thickness’ of each wedge 127 is defined with reference to the radial position of the crushing surface 218 at each wedge relative to the radial position of crushing surface 214 at each channel 200. The radial thickness then decreases in the axial direction towards lowermost region 204. That is, a radial distance of surface region 204 is substantially equal to the radial distance at a lowermost surface region 211 of channel 200 (relative to axis 115) where regions 204, 211 are at the same axial position. Additionally, shell 106 comprises a plurality of recesses 219 embedded within the mount surface 118 having a position corresponding to the position directly behind wedges 127. These recesses 219 provides that the shell wall thickness is substantially uniform in the circumferentially direction around the axis. This is advantageous to moderate the cooling rate at the shell wall and eliminate material porosity of the cast shell.
Referring to
As illustrated in
Surface 208 is substantially concave in the axial direction so as to provide a smooth transition of the radial position of the crushing surface 208 at the lowermost region 204 of each wedge 127 and the lower half 202. Additionally, and as illustrated in
As illustrated, a width in a circumferential direction of surface 208 increases axially downward from upper region 212 to lowermost region 204. Accordingly, an area of side surfaces 207 decreases axially downward from edge 213 to lowermost end 204.
Each wedge 127 is substantially symmetrical about a vertically extending plane represented as B-B. That is, a radial extension of each wedge 127 is symmetrical about the plane of B-B. Similarly, a radial extension of the shell wall 116 at the region of each channel 200 is symmetrical about a corresponding vertical plane represented by C-C.
Wedges 127 reduce the available volume of the crushing zone 104 between shells 105, 106 above the lower region 202 of shell 106. Wedges 127 are effective to guide material to be crushed into channels 200 and in contact with side surfaces 207 and channel surface 214 being positioned opposed to the crushing surface 125 of outer shell 106. In particular, wedges 127 are effective to control the delivery of the material to be crushed to the lower region of the crushing zone 104 corresponding to the lower region 202 of shell 106.
An area function at each axial position between surfaces 125, 117 is represented by line 605. A minimum 606 in the area function represents the ‘choke point’ of conventional crushing shells without directing wedges 127 and this is represented by line 608. According to this conventional configuration, a horizontal bisecting line 607 defines an upper crushing region 603 above choke point 607 and a lower crushing region 604 below choke point 607.
The effect of configuring shell 106 with a plurality of circumferentially spaced wedges 127 at upper region 201 is to reduce the area function and this represented by line 609. As will be noted, the choke point is accordingly displaced axially upward in direction A of
The inventors have determined via assessment of the crusher dynamics and comparisons with field testing that the crusher capacity is determined by the volume of the choke zone. Importantly, the crusher dynamics assessment has confirmed that most of the crushing in the crusher within zone 104 is due to attrition (being inter-particle crushing). Additionally, material crushed within upper zone 603 is transferred to lower zone 602 by gravity and accordingly there is a mass balance between the crushing zones 603, 604. Consequently, the inventors have identified that the volume of material that is required to be crushed within lower zone 604 is controlled by the choke zone 607. If a compression ratio of material in zone 604 yields a higher force than a predetermined value of the crusher control system, the system will open the crushing zone 104 by effective separation of the shells 105, 106. Accordingly, there are two mechanisms to increase the compression, firstly, the crushing force between regions 600, 601, 602 must be increased or secondly, the volume of material within the lower crushing zone 604 must be decreased.
Accordingly, the inventors have identified that the problem of accomplishing reduction within a crusher is due to the fact that as the crusher reduces the crushing gap during gyroscopic procession, the size of the choke zone 607 and the size of the closed crushing zone 604 do not decrease by the same amounts. The result is that a conventional crusher will eventually allow transfer of more material from upper zone 603 to lower zone 604 than can be crushed in the lower zone 604 due to limitations in the available crushing force at this zone 604.
The present wedge 127 and channel 200 configuration of shell 106 is effective to decrease the amount of material within upper crushing zone 603 being available to be fed to the lower crushing zone 604. Accordingly, the present shell configuration restricts the volume of material to be crushed at the crushing zone 603 and effectively moves the choke zone 610, 611 axially upward. Accordingly, the choke zone 611 of the subject invention is proportionally smaller than zone 607 of conventional shells so as to balance crushing capacity with an effective increase in reduction. Importantly, wedges 127 do not extend into lower half 202 of crushing surface 117 such that the volume of the lower crushing zone 604 is unchanged relative to a conventional crusher arrangement.
Wedges 127 are therefore effective to allow the crusher to be operated at a smaller CSS without having to increase the crushing force. Where the crusher is operated according to a closed crushing circuit (coupled to a downstream screen) an increase in the process capacity is achieved as the size distribution of material exiting the crusher is substantially uniform and within the predetermined reduction range. That is, the need to purge the crusher due to choking is avoided together with the creation of very ‘fine’ particulates (due to over crushing within the lower crushing zone 604) being resultant from crusher choking.
In particular, each wedge 127 is defined by a pair of axially extending side surfaces 207 that represent shoulders 218 defining each channel 200. Each of the left hand and right hand side surfaces 207 are identical to one another such that each wedge 127 is symmetrical about a vertical plane B-B extending axially through the shell wall 110. Similarly, each channel 200 is substantially symmetrical about a vertical plane C-C extending axially through shell wall 110.
Each channel 200 is accordingly defined by the pair of opposed side surfaces 207 of the shoulders 218 neighbouring wedges 127. Each side surface 207 comprises a generally wedge-shaped profile having a pointed lowermost end 217 and an uppermost end defined by the leading radial edge 213. As each wedge surface 208 tapers towards the radial position of each channel surface 214 in the axial direction from circumferential edge 209 to the lowermost region 204, side surfaces 207 also decrease in area from the uppermost radial edge 213 to the lowermost and thinnest end 217. Accordingly, a surface area of each side surface 207 that defines, in part, each channel 200 is substantially identical such that each channel 200 is symmetrical about plane C-C. Accordingly, material is directed to flow axially within each channel 200 and is prevented from passing circumferentially outward from each channel 200 by the axially extending shoulders 218. Each wedge 127 therefore acts to guide material to pass axially downward through each channel 200 by representing an obstruction to any circumferential flow of material within each channel 200. In particular, shoulders 218 ensure an axially downward flow of material is maintained and provide a means of guiding and retaining the material flow along each channel 200 from upper end 210 to lower end 211.
| Number | Date | Country | Kind |
|---|---|---|---|
| 13174042 | Jun 2013 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/060512 | 5/22/2014 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2014/206658 | 12/31/2014 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20060219830 | Nilsson-Wulff et al. | Oct 2006 | A1 |
| Number | Date | Country |
|---|---|---|
| 101905181 | Dec 2010 | CN |
| 1757362 | Jan 1971 | DE |
| 1810270 | Mar 1972 | DE |
| 2542660 | Mar 1977 | DE |
| 0567077 | Oct 1993 | EP |
| 1671339 | Aug 1991 | SU |
| 2006101432 | Sep 2006 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20160346786 A1 | Dec 2016 | US |
