A crusher
The crusher's innovative annular bottom plate with a vertically extending return and optimized seal configuration addresses the issue of material ingress and wear, enhancing operational reliability and extending service life in wet mining conditions.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- WESCONE DISTRIBUTION PTY LTD
- Filing Date
- 2025-11-26
- Publication Date
- 2026-06-04
AI Technical Summary
Gyratory crushers experience operational failures and reduced service life due to ingress of wet and abrasive crushed material, which causes wear and failure of the annular resilient member (bell seal) and drive assembly, particularly in mining operations with increased moisture content.
The crusher design incorporates an annular bottom plate with a vertically extending return that extends a major portion of the distance between the complementary annular surface and the inner wall, combined with an angled section to prevent material buildup and an optimized seal configuration to reduce ingress, enhancing the anti-rotation system's effectiveness.
This design significantly reduces material ingress and wear, extending the crusher's service life from 2 months to 12 months, ensuring reliable operation in wet conditions.
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Abstract
Description
A CRUSHERTECHNICAL FIELD
[0001] The present invention relates to a crusher for frangible or friable material, in particular to a crusher for sample preparation.BACKGROUND ART
[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.
[0003] Crushers of gyratory type may be used in a range of applications, including in mining and metallurgical operations, for example in the iron mining industry. Such crushers are particularly useful for crushing samples for chemical and physical assay. The Applicant has commercialised such sample crushers in a range of mining sites. It will be understood that such gyratory crushers may be applied for different purposes than sample crushing.
[0004] The Applicant’s Series 4 crusher is described in US Patent No.12, 023, 682, the contents of which are hereby incorporated herein by reference for all purposes. This crusher successfully addressed operational challenges in processing of lump ore, of greater particle size than 40-50mm, as desired by customers. Such larger lump ore particle size led to failure of the crusher, particularly at the crusher head.
[0005] However, the Applicant’s earlier Series 3 crusher is still produced and it remains useful for a range of sample crushing applications.
[0006] Both the Applicant’s Series 3 and Series 4 crushers - as indeed other gyratory crushers - comprise, in their broadest form, a bowl defining a chamber for receiving material to be crushed and further defining a discharge opening at the base thereof through which crushed material is able to discharge. The crusher also includes a crushing head mounted in the bowl in an offset position with respect to a central axis of the bowl and a drive assembly for driving the crushing head within the bowl forimparting gyratory motion to the crushing head about a gyratory axis inclined with respect to and intersecting the central axis. The arrangement is such that frangible or friable material received into the bowl is subjected to crushing between an inner peripheral surface of the bowl and an outer peripheral surface of the crushing head by the gyratory motion of the crushing head.
[0007] The crusher further includes a system for restraining rotation of the head relative to the bowl and the gyratory axis, the system including an annular resilient member, or bell seal, connected between a bottom peripheral surface of the crushing head and an annular bottom plate. The bottom plate is biased, by circumferentially spaced biasing means, to frictionally engage with a complementary annular surface of a fixed structure (or base spider) of the crusher. The bottom plate is also connected to the base spider but in a manner that allows a degree of rotation of the bottom plate. The complementary annular surface is substantially co-axial with the annular bottom plate.
[0008] The biasing means is operable to provide sufficient frictional contact to restrain the crushing head from rotating relative to the bowl and gyratory axis while the head is gyrating in the absence of feed to the bowl. The system enables the crushing head to rotate relative to the bowl and gyratory axis, during a crushing operation, by slippage between the annular bottom plate and the complementary annular surface of the fixed structure. The annular bottom plate, having the above mentioned degree of rotation, acts as a clutch frictionally engaging with the complementary annular surface of the fixed structure.
[0009] The annular resilient member is called a bell seal because of its typical shape and it provides a seal between the gyratory and stationary parts of the crusher. Where such bell seal was not present, crushed material could enter the drive assembly and bog the crusher which has not typically caused operational issues where a dry feed, such as an iron ore, is crushed.
[0010] As iron mining operations proceed, and has been found in the Pilbara Region of Western Australia, mining depths increase approaching a water table where iron ore moisture content increases, for example from less than 5 wt% to up to 10 wt% or higher. Such wetter ore feed has caused bogging or stoppage of operation of the Applicant’s Series 3 and Series 4 crushers which is undesirable from a customer perspective. One cause of stoppage is failure of the bell seal. Another cause of stoppage, which mayitself cause failure of the bell seal, is buildup of wet crushed material on an inner wall of the fixed structure. Wet crushed material may also enter a small space between the annular bottom plate of the crushing head and the complementary annular surface of the fixed structure interfering with rotation of the crushing head. Such material is also abrasive and is likely to cause accelerated destructive wear over time.
[0011] It is against this background that the present invention has been developed.SUMMARY OF INVENTION
[0012] In one embodiment, the present invention provides a crusher for frangible or friable material comprising: a bowl having a chamber for receiving a feed of frangible or friable material and a discharge opening disposed at the base thereof, said discharge opening defining a throat having a circumferential wall and the bowl having a central axis; a crushing head disposed within said discharge opening and mounted on a hub, said crushing head having a crushing face disposed in spaced relation to said circumferential wall of said throat defining a nip between said wall and the crushing face of said crushing head, said crushing head having a gyratory axis extending at an angle to the central axis; a housing connected to the base of the bowl and having a bore extending toward the central axis, the bore being defined by an inner wall of the housing, the inner wall having an outward horizontal portion extending radially outward of a peripheral surface of the crushing head; a drive assembly including an input shaft co-operable with a rotatable eccentric shaft for rotating said crushing head within said bowl and about said gyratory axis in a nutating motion, said input shaft being accommodated within the bore defined by the inner wall of the housing; and an annular resilient member connected between a bottom surface of the hub and an annular bottom plate frictionally engaging with a complementary annular surface of an inward portion of the inner wall of the housing, said complementary annular surfacebeing disposed below the crushing head radially inward of the peripheral surface of the crushing head, wherein said annular bottom plate includes a vertically extending return, said vertically extending return extending downward from the complementary annular surface at least a major portion of the distance between the complementary annular surface of the inner wall and a surface of the outward horizontal portion of the inner wall.
[0013] By a “major portion of the distance” is intended greater than 60% of the distance, preferably 65% of the distance, more preferably between 65% and 75% or 65- 85% of the distance and most preferably between 65% and 80% of the distance. This distance is expected to be sufficient to significantly reduce buildup of material and consequential ingress of material between the complementary annular surface and the annular bottom plate. The above ranges are a guide because length of the vertically extending return is desirably maximised to reduce buildup of material and enable efficient crusher operation without substantial interference with the structural integrity of the inner wall.
[0014] It will be understood that the vertically extending return is disposed proximate a vertical portion of the inward portion of the inner wall. Preferably, the vertical portion of the inner wall is provided with an angled section, the angled section extending downwardly at an acute angle. The acute angle is chosen to both discourage build up of material while enabling efficient fabrication. A convenient angle is 45 degrees downward from the horizontal but this is exemplary only. The angle is desirably optimised as a function of the material to be crushed. The angled section may be surface treated, for example with a coating such as a non-stick coating, for example of ceramic, polytetrafluoroethylene (Teflon) dependent on feedstock characteristics.
[0015] The angled section conveniently terminates at its lower end in a groove provided to direct crushed material to a discharge at the bottom of the crusher. The groove forms a transition between the vertical portion and outward horizontal portion of the inner wall.
[0016] In one embodiment, the bowl may comprise feed and discharge sections, each defined by a wall and spaced by a mid-section of the bowl also defined by a wall, wherein thickness of the wall defining at least the mid-section of the bowl is greater than a thickness of the wall of the discharge section.
[0017] In another aspect, the present invention provides an annular bottom plate for the gyratory crusher described above. The annular bottom plate includes a vertically extending return, said vertically extending return configured to extend downward from the complementary annular surface at least a major portion of the distance between the complementary annular surface of the inner wall and a surface of the outward horizontal portion of the inner wall. The annular bottom plate acts as a clutch.
[0018] In another aspect, the present invention provides a method of maintaining or retrofitting a gyratory crusher comprising: a bowl having a chamber for receiving a feed of frangible or friable material and a discharge opening disposed at the base thereof, said discharge opening defining a throat having a circumferential wall and the bowl having a central axis; a crushing head disposed within said discharge opening and mounted on a hub, said crushing head having a crushing face in spaced relation to said circumferential wall of said throat defining a nip between said wall and the crushing face of said crushing head, said crushing head having a gyratory axis extending at an angle to the central axis; a housing connected to the base of the bowl and having a bore extending toward the central axis, the bore being defined by an inner wall of the housing, the inner wall having an outward horizontal portion extending radially outward of a peripheral surface of the crushing head; and a drive assembly including an input shaft co-operable with a rotatable eccentric shaft for rotating said crushing head within said bowl and about said gyratory axis in a nutating motion, said input shaft being accommodated within the bore, comprising connecting an annular resilient member between a bottom surface of the hub and an annular bottom plate frictionally engaging with a complementary annular surface of an inward portion of the inner wall of the housing, said complementary annular surface being disposed below the crushing head radially inward of the peripheral surface of the crushing head; andwherein said annular bottom plate includes a vertically extending return, said vertically extending return extending downward from the complementary annular surface a major portion of the distance between the complementary annular surface of the inner wall and a surface of the outward horizontal portion of the inner wall.
[0019] The provision in a gyratory crusher of annular bottom plate with extended return, particularly with configuration of the inner wall of the housing as described above, is expected to prevent ingress of wet and abrasive material into the space between bottom plate and complementary surface. This reduces risk of wear and premature life cycle failure, such as of the annular resilient member (also known as a bell seal) or the drive assembly of the crushing head.BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Further features of the crusher of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:Figure 1 is a cross-sectional view of a gyratory crusher according to the prior art as represented by US Patent No. 12,023,682.Figure 2 is a detail cross-sectional view showing the relationship between crushing head hub and inner wall of the housing in the gyratory crusher of Figure 1.Figure 2a is a detail cross-sectional view of the bell seal of Figures 1 and 2.Figure 3 is a detail cross-sectional view showing the relationship between crushing head hub and inner wall of the housing in a gyratory crusher according to one embodiment of the present invention.Figure 3a is a detail cross-sectional view of the bell seal of Figure 3.Figure 4 is a cross-sectional view of the gyratory crusher having crushing head hub and inner wall of the housing as shown in detail in Figures 3 and 3a.DESCRIPTION OF PREFERRED EMBODIMENTS
[0021] In the prior art arrangement of Figures 1, 2 and 2a, there is shown a gyratory crusher 10 having an upper portion 10A comprising a bowl 104 having a chamber 104a for receiving a lump iron ore feed and a discharge opening 104j disposed at its base. Chamber 104a comprises two intersecting frusto-conical portions. Discharge opening 104j defines a throat having a circumferential wall 104k. Bowl 104 has a substantially smooth cylindrical surface at its mid-section wall 104c. Bowl 104 is otherwise as described in US Patent No. 12,023,682 incorporated by reference. Bowl 104 is threadably connected to a fixed structure (i.e. fixed to a floor) or housing referred to as a base spider 105.
[0022] A crushing head 102 is disposed to rotate within the discharge opening 104j of bowl cavity 104a. A gyratory axis 101a extends along the eccentric shaft 103 at an angle (about 2 degrees) to the central axis 101b. Crushing head 102, which is symmetrical about gyratory axis 101a, comprises a wear resistant head liner or mantle 102a bolted to a hub 102b.
[0023] Head liner 102a has a lower frusto-conical crushing face 102d integrally formed with a cylindrical portion 102e having a crown 102aa, these portions of the head liner 102a defining a hollow bore 102f for accommodating hub 102b. In this embodiment, the wall of the crown 102aa is thickest (e.g. 5-6mm) at the portions 102ab where crown 102aa transitions to cylindrical portion 102e, this thickness tapering down towards the bottom of the head liner 102a as a consequence of reduced stress profile in cylindrical portion 102e and crushing face 102d compared to the crown portion 102aa. The crown portion 102aa therefore has a structure that assists fragmentation of material, i.e. the purpose of crushing. The vertically extending side walls of cylindrical portion 102e are substantially parallel along their length providing a substantially cylindrical shape for the head liner 102a.
[0024] Crushing face 102d is disposed in spaced relation to circumferential wall 104k to define an annular nip of cyclically variant dimension typical of gyratory crushers. The arrangement is such that iron ore, or other frangible or friable material, fed into the bowlcavity 104a is subjected to crushing by the nutating motion of the crushing head 102 relative to circumferential wall 104k, with opposite sides of the crushing head 102 cooperating with a lower face of the circumferential wall 104k of the throat to maintain the gap of the nip during an entire oscillation of the crushing head 102.
[0025] Base spider 105 supports bowl 104 and accommodates a drive assembly 106 of a powertrain for transmitting power from a prime mover, such as an engine, through a transmission including input shaft 106a to rotate an eccentric shaft 103 which is journalled within a roller bearing assembly 103d disposed within the bore of the crushing head bearing housing 102b. Further description of eccentric shaft 103, the drive assembly 106 and the transmission including input shaft 106a is provided in US Patent No. 12,023,682 incorporated by reference.
[0026] Crusher 10 is operated with feed material to be crushed fed into bowl 104. The movement of the crushing head 102, during rotation of eccentric shaft 103, exerts a crushing action on the feed material. As shaft 103 rotates, the gyratory motion of crushing head 102 causes the location of upper maximum and minimum gap openings, and of lower minimum and maximum gap openings to be in successive diametrical planes of bowl 104.
[0027] Crusher 10 has an annular resilient seal or bell seal 70 which excludes dirt, water and chemicals and retains lubricants within the drive assembly 106 and chamber 107. Bell seal 70, which as its name suggests has the shape of a bell, also prevents free rotation of the crushing head 102 in the absence of feed to the crusher. Bell seal 70 forms part of an anti-rotation system of crusher 10.
[0028] A preferred embodiment of bell seal 70 has respective upper and lower peripheral beads 72 and 73 as shown in Figure 2a. An upper clamping assembly 76 secures bell seal 70 in relation to bottom surface 74 of the hub 102b. A lower clamping assembly 77 secures bell seal 70 in relation to an inward portion 105a of the inner wall 105A of base spider 105.
[0029] Upper clamping assembly 76 simply comprises an annular clamp plate 90 which is retained on hub 102b by bolts 91. The upper surface of plate 90 is grooved (as also is bottom surface 74 of hub 102b if required) for locating bead 72 securely and sealinglyagainst bottom surface 74. Thus, with rotation of crushing head 102, bell seal 70 is drawn by its bead 72 to rotate with crushing head 102.
[0030] Lower clamping assembly 77 has upper and lower clamping plates 92 and 93 each grooved to locate bead 73. The plates 92 and 93 are secured together to securely and sealingly hold bead 73, by bolts 94. Lower clamping plate 93 may also be referred to as bottom plate 93.
[0031] Bottom plate 93 frictionally engages with a complementary annular surface 105ac of inward wall portion 105a of the inner wall of base spider 105 as shown in Figures 1, 2 and 2a. An outward wall portion 105b of the inner wall extends horizontally above a sleeve 106f having a bore 106d in which input shaft 106a of drive assembly 106 is accommodated. As shown, there is metal to metal contact between bottom plate 93 and complementary annular surface 105ac of inward wall portion 105a. However, in alternative embodiments, the bottom plate 93 could be provided with a separate frictional lining.
[0032] An annular biasing plate 96, which has a stepped lower surface defining a lip 96a, fits radially within lower clamping assembly 77 with lip 96a resting on the exposed top surface of bottom plate 93. Additionally, a plurality of circumferentially spaced springs 97 are provided to apply pressure to annular biasing plate 96. As shown, each spring 97 is secured into position and compressed by a respective bolt 98 which passes through a respective aperture in annular biasing plate 96 and is threaded into a sleeve connected to the inward wall portion 105a of the inner wall of base spider 105.
[0033] Anti-rotation system 12 operates as follows. Frictional engagement of bottom plate 93 with annular complementary surface 105ac of the inward wall portion 105a of the inner wall enables each of clamping assemblies 76 and 77 and bottom plate 93 to rotate with hub 102b and crushing head 102. Springs 97 are arranged so that they compress bottom plate 93 against annular complementary surface 105ac but without the need for the springs 97 to expand and compress as the crushing head 102 gyrates.
[0034] As upper bead 72 of bell seal 70 is clamped directly to bottom surface 74 of the hub 102b, seal 70 is carried with crushing head 102 in the event of slight circular movement of the latter.
[0035] The combined effect of all springs 97 provides sufficient friction between bottom plate 93 and annular complementary surface 105ac to prevent rotation of the crushing head 102 when gyrating with the bowl 104 empty. However, such friction does not prevent the crushing head 102 creeping around as frangible and friable materials are crushed.
[0036] Lower clamping plate 93 has an annular downwardly extending lip 93a, i.e. a short extension having length (x) of for example 3 mm, which is seated on an annular ledge 105ab formed in vertically extending portion 105aa of the inward wall portion 105a. Downwardly extending lip 93a bears against the vertically extending portion 105aa. The terminal end of downwardly extending lip 93a and annular ledge 105ab have a level located substantially above an upper surface 105c of the inward wall portion 105a, upper surface 105c being disposed radially outward from the crushing head 102. Length x extends a minor portion, about 24%, of the distance (12.5mm in this example) between the complementary surface 105ac of inward wall portion 105a and upper surface 105c of the outward wall portion 105b.
[0037] Below annular ledge 105ab, vertically extending portion 105aa transitions into a radiused portion of a groove 105d formed in the inner wall 105a. Groove 105d assists flow of crushed material towards discharge chamber 1050 of the crusher 10.
[0038] When wetter material is crushed, crushed material builds up in groove 105d with finer material being driven into the gap between the terminal end of downwardly extending lip 93a and ledge 105ab of the inward wall portion 105a. Such ingress of crushed material and other undesirable contaminants, which are abrasive in nature, reaches the interface between complementary surface 105ac of inward wall portion 105a and the frictionally engaging lower clamp plate 93 causing, with accumulation, substantial wear and failure. The bell seal 70 may also fail as a consequence allowing ingress of crushed material and other undesirable contaminants into the drive assembly 106 causing another point of failure. For example, service life of such a crusher 10 may be 2 months or less dependent on the nature of the material it is handling, for example wet iron ore.
[0039] Referring to Figures 3, 3a and 4, there is shown a gyratory crusher 110 which also has a bell seal 70 connecting hub 102b and inner wall 1105A according to one embodiment of the present invention. For ease of reference, those parts of the crusherFigures 1 and 2 are designated by the same reference numeral in all. Further features are designated by the same reference numeral plus 100 or plus 1000 as apparent from the following description. It will be understood that the form and functioning of so designated parts can be understood from the description of Figures 1 ,2 and 2a. Further description therefore principally relates to configuration of the inner wall 1105A and its relationship with a reconfigured lower clamping plate 193.
[0040] A preferred embodiment of bell seal 70, forming part of the anti-rotation system has an upper peripheral bead 72 and a lower peripheral bead 73 as shown in Figure 3a. Upper clamping assembly 76 simply comprises an annular clamp plate 190 which is retained on crushing head 102 by bolts 91. The upper surface of plate 90 is grooved (as also is surface 74 of the crushing head 102 if required) for locating upper peripheral bead 72 securely and sealingly against bottom surface 74 of hub 102b. Thus, with rotation of crushing head 102, bell seal 70 is drawn by its bead 72 to rotate with crushing head 102 as part of an anti-rotation system.
[0041] Lower clamping assembly 77 has upper and lower clamping plates 192 and 193 each grooved to locate bead 73. The plates 192 and 193 (which is also referred to as a bottom plate) are secured together to securely and sealingly hold bead 73, by bolts 94 to inward wall portion 1105a.
[0042] Bottom plate 193 frictionally engages with a complementary annular surface 1105ac of inward wall portion 105a of the inner wall 1105A of base spider 105. An outward wall portion 105b extends horizontally above a sleeve 106f having a bore 106d in which input shaft 106a of drive assembly 106 is accommodated. As shown, there is metal to metal contact between bottom plate 193 and complementary annular surface 1105ac of inward wall portion 1105a. However, in alternative embodiments, the bottom plate 193 could be provided with a separate frictional lining as known in the crushing art.
[0043] An annular biasing plate 96, which has a stepped lower surface defining a lip 96a, fits radially within lower clamping assembly 77 with lip 96a resting on the exposed top surface of bottom plate 193. Additionally, a plurality of circumferentially spaced springs 97 are provided to apply pressure to annular biasing plate 96. As shown, each spring 97 is secured into position and compressed by a respective bolt 98 which passesthrough a respective aperture in annular biasing plate 96 and is threaded into a sleeve connected to the inward wall portion 1105a of the inner wall 1105A of base spider 105.
[0044] The anti-rotation system 12 operates as follows. Frictional engagement of bottom plate 193 with annular complementary surface 1105ac of the inward wall portion 1105a of the inner wall enables each of clamping assemblies 76 and 77 and bottom plate 193 to rotate with hub 102b and crushing head 102. Springs 97 are arranged so that they compress bottom plate 193 against annular complementary surface 105ac but without the need for the springs 97 to expand and compress as the crushing head 102 gyrates.
[0045] As upper bead 72 of bell seal 70 is clamped directly to bottom surface 74 of the hub 102b, seal 70 is carried with crushing head 102 in the event of slight circular movement of the latter.
[0046] The combined effect of all springs 97 provides sufficient friction between bottom plate 93 and annular complementary surface 105ac to prevent rotation of the crushing head 102 when gyrating with the bowl 104 empty. However, such friction does not prevent the crushing head 102 creeping around as frangible and friable materials are crushed.
[0047] In addition, bottom plate 193 has a vertically extending return 193a, i.e. a substantially longer extension than lip 93a, which sealingly engages against vertically extending portion 1105aa of the inward wall portion 105a. Return 193a of lower clamping plate 193 extends a major portion of the distance (X) between the complementary surface 1105ac of the inward wall portion 1105a and the upper surface 105c of the outward wall portion 105b, upper surface 105c being disposed radially outward from the crushing head 102. X is greater than 65% of the distance, more preferably between 65% and 85% of the distance and most preferably between 65% and 80% of the distance between the complementary surface 105ac and upper surface 105c of the inner wall 1105A. As shown, X is about 68% of the distance between the complementary surface 105ac of the inward wall portion 1105a and upper surface 105c of the outward wall portion 105b. The above ranges for X are a guide, dependent on the material (e.g. cast iron or steel) used for fabrication of base spider 105 and its the inner wall or arm 1105A. The length of the vertically extending return 193a is desirablymaximised to reduce buildup of material and enable efficient crusher operation without substantial interference with the structural integrity of inner wall 1105A.
[0048] The vertically extending portion 1105aa of inward wall portion 1105a is provided with an angled section 1105ab, the angled section 1105ab extending downwardly at an acute angle. The acute angle is chosen to both discourage build up of fragmented material while enabling efficient fabrication of crusher 110. A convenient angle for the wet iron ore being crushed is 45 degrees downward from the horizontal, as shown in Figures 3, 3a and 4, but this is an exemplary angle (analogous to slip angle for the wet iron ore) only and could desirably be optimised as a function of the material being crushed by crusher 110. The slip angle or angle of repose may be determined, for example, by methods as understood in the art and as described in Al-Hashemi, HMB et al., A review on the angle of repose of granular materials, Powder Technology, (2018), 330, 397-417.
[0049] The angled section 1105ab may be surface treated, for example with a coating such as a non-stick coating, for example of ceramic or polytetrafluoroethylene (Teflon). Such coating may help to avoid sticking of material to angled section 1105ab.
[0050] The angled section 1105ab conveniently terminates at its lower end in a radiused groove 105d located above input shaft 106a, on one side of crusher 110, to assist flow of crushed material to a discharge chamber 1050 at the bottom of the crusher 110. The groove 105d forms a transition between the inward wall portion 105a and outward wall portion 105b.
[0051] The vertical length of return 193a of bottom plate 193 enables a significantly greater sealing area than the bell seal 70 of Figures 1, 2 and 2a. Return 193a therefore provides an effective seal against fine solids and fluids which can otherwise intrude into the sealing space underneath lower clamping assembly 177. The intrusion of such foreign material would accelerate wear on bottom plate 193 and annular complementary surface 105ac interfering with operation of the anti-rotation system. On failure of the bell seal 70, such foreign matter would also contaminate lubricant inside the crushing mechanism, reducing the service life of crusher 110 as described above in the case of crusher 10. Thus, the configuration of bottom plate 193 and inward wall portion 1105a allows the life of crusher 110 to be prolonged. In one example, service life of crusher 110 was extended from 2 months to 12 months, a very substantial improvement.
[0052] Modifications and variations to the crusher described here may be apparent to the skilled reader of this disclosure. Such modifications and variations are deemed within the scope of the present invention.
[0053] Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
Claims
CLAIMS1. A crusher for frangible or friable material comprising: a bowl having a chamber for receiving a feed of frangible or friable material and a discharge opening disposed at the base thereof, said discharge opening defining a throat having a circumferential wall and the bowl having a central axis; a crushing head disposed within said discharge opening and mounted on a hub, said crushing head having a crushing face disposed in spaced relation to said circumferential wall of said throat defining a nip between said wall and the crushing face of said crushing head, said crushing head having a gyratory axis extending at an angle to the central axis; a housing connected to the base of the bowl and having a bore extending toward the central axis, the bore being defined by an inner wall of the housing, the inner wall having an outward horizontal portion extending radially outward of a peripheral surface of the crushing head; a drive assembly including an input shaft co-operable with a rotatable eccentric shaft for rotating said crushing head within said bowl and about said gyratory axis in a nutating motion, said input shaft being accommodated within the bore defined by the inner wall of the housing; and an annular resilient member connected between a bottom surface of the hub and an annular bottom plate frictionally engaging with a complementary annular surface of an inward portion of the inner wall of the housing, said complementary annular surface being disposed below the crushing head radially inward of the peripheral surface of the crushing head, wherein said annular bottom plate includes a vertically extending return, said vertically extending return extending downward from the complementary annular surface at least a major portion of the distance between the complementary annular surface of the inner wall and a surface of the outward horizontal portion of the inner wall.
2. The crusher of claim 1 , wherein said vertically extending return extends downward a distance greater than 60% of the distance between the complementary annular surface of the inner wall and the surface of the outward horizontal portion of the inner wall.
3. The crusher of claim 2, wherein said vertically extending return extends downward a distance between 65% and 70% of the distance between the complementary annular surface of the inner wall and the surface of the outward horizontal portion of the inner wall.
4. The crusher of any one of the preceding claims, wherein the vertically extending return is disposed proximate a vertical portion of the inward portion of the inner wall and is provided with an angled section extending downwardly at an acute angle.
5. The crusher of claim 4, wherein said acute angle is 40-60 degrees, preferably 40- 55 degrees.
6. The crusher of claim 4 or 5, wherein said angled section is surface treated with a coating.
7. The crusher of any one of claims 4 to 6, wherein said angled section terminates at a lower end in a groove provided to direct crushed material to a discharge.
8. The crusher of any one of the preceding claims, wherein said bowl comprises feed and discharge sections, each section being defined by a wall and spaced by a mid-section of the bowl also defined by a wall, wherein thickness of the wall defining at least the mid section of the bowl is greater than a thickness of the wall of the discharge section.
9. An annular bottom plate for a gyratory crusher as claimed in any one of the preceding claims.
10. A method of maintaining or retrofitting a gyratory crusher comprising:a bowl having a chamber for receiving a feed of frangible or friable material and a discharge opening disposed at the base thereof, said discharge opening defining a throat having a circumferential wall and the bowl having a central axis; a crushing head disposed within said discharge opening and mounted on a hub, said crushing head having a crushing face in spaced relation to said circumferential wall of said throat defining a nip between said wall and the crushing face of said crushing head, said crushing head having a gyratory axis extending at an angle to the central axis; a housing connected to the base of the bowl and having a bore extending toward the central axis, the bore being defined by an inner wall of the housing, the inner wall having an outward horizontal portion extending radially outward of a peripheral surface of the crushing head; and a drive assembly including an input shaft co-operable with a rotatable eccentric shaft for rotating said crushing head within said bowl and about said gyratory axis in a nutating motion, said input shaft being accommodated within the bore, comprising connecting an annular resilient member between a bottom surface of the hub and an annular bottom plate frictionally engaging with a complementary annular surface of an inward portion of the inner wall of the housing, said complementary annular surface being disposed below the crushing head radially inward of the peripheral surface of the crushing head, wherein said annular bottom plate includes a vertically extending return, said vertically extending return extending downward from the complementary annular surface at least a major portion of the distance between the complementary annular surface of the inner wall and a surface of the outward horizontal portion of the inner wall.