AU607892B2 - Shell liner assembly - Google Patents

Description

P18/7/78 i~ AS :DW PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne, Australia i 'i I: i; i AJ-AI 5 3 5 8 3 8 6 WORLD INTELLECTUAL 0 RG ET Internati I utaN PCT INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 86/ 04267 B02C 17/22 Al (43) International Publication Date: 31 July 1986 (31.07.86) (21) International Application Number: PCT/US86/00156 (81) Designated States: AU, BR, FI, GB, JP, KR, NO, SE,

SU.

(22) International Filing Date: 24 January 1986 (24.01.86) Published (31) Priority Application Number: 694,804 With international search report.

With amended claims.

(32) Priority Date: 25 January 1985 (25.01.85) (33) Priority Country: US (71) Applicant: EVANS PRODUCTS COMPANY [US/US]; This docment contains the 100 West Tenth Street, Wilmington, DE 19801 amendments made under Section 49 and is correct for (72) Inventors: KJOS, David, M. 3905 Orleans Lane North, printing.

Plymouth, MN 55441 DUGGER, Charles, B., Jr. 8117 Chipwood Way, Orangevale, CA 95662

(US).

(74) Agents: SUMNERS, John, S. et al.; Merchant, Gould, A. O J I EP 1986 Smith, Edell, Welter Schmidt, 1600 Midwest Plaza AUSTRALIAN Building, Minneapolis, MN 55402 (US).

13A;UG 1986 PArENT

OFFICE

(54) Title: SHELL LINER ASSEMBLY (57) Abstract 1 6 0 A liner assembly for the cylindri- 1 cal shell (12) of an ore grinding ma- 1 19 chine, which is arranged in a series of 16 axial sections each being made up of individual liner segments (13-16) that cover substantially the entirety of 14 the inner cylindrical surface of the shell. Each axial section is generally annular in configuration and is formed with a plurality of ramp-like surfaces that extend circumferentially and define sequential steps, with the lowest point of one ramp-like surface adjacent the highest point of another. The ramp-like surfaces of each axial section are circumferentially staggered with respect to the ramp-like surfaces of an adjacent: annular section, resulting in increased grinding efficieny of 4 the grinding machine.

16b 16 16 160 WO 86/0426 PCT/US86/00156 SHELL LINER ASSEMBLY Technical Field The invention relates generally to ore processing, and is specifically directed to an improved liner assembly for the cylindrical shell of an ore grinding machine.

Background of the Invention Ore grinding or comminuting machines have long been used to reduce the size of ore fragments to small particles for further processing.

One type of commonly used machine comprises a cylindrical shell in which ore particles enter through an opening in one axial end and reduced particles are discharged from the opposite end. Comminution occurs by rotating the shell, causing the ore fragments to tumble on one another, resulting in grinding and a reduction in size.

Typically, the inner cylindrical surface of the shell is lined with a plurality of thick liner segments that cover substantially the entire shell surface. The exposed grinding surface of the liner assembly is configured to carry the ore fragments upwardly as the shell rotates, causing them to tumble back into the charge of ore fragments, resulting in comminution. I It is well established that, in any rotary grinding mill, a portion of the tumbling charge of ore fragments consists of a relatively inactive region that is generally kidney shaped. In the "kidney", there is very little movement of the particulate matter, and as a result, very little useful grinding takes place.

WO 86/04267 PCT/US86/00156 The size of the "kidney" is dependent on a number of factors including shell diameter, to what extent the mill is filled, rotational velocity of the shell, liner configuration, ball size (if balls are used to assist in comminution) and percent moisture in the ore charge. However, in any tumbling charge of ore particles, a kidney exists which adversely affects ore com-1 minution.

With increased sizes of ore grinding mills, useful grinding work appears to be limited to and dependent upon a maximum depth of the ore charge (as measured from the bottom of the shell to the top of the charge at rest).

Grinding efficiency drops as the ore charge depth is increased beyond an upper limit. It is believed that this efficiency loss is related to an increase in the size of the ore charge kidney, which is accompanied by increased slippage of the active outer charge layers and the inactive layers in the kidney.

Grinding efficiency refers to the volume of reduced particles discharged from the mill in a given unit of time. If the size of the charge is increased, it is potentially possible for more reduced particulate matter to be discharged from the mill in a given unit of time. However, the larger the ore charge, the greater the size of the kidney, which significantly reduces the overall efficiency. Consequently, even though the charge may be larger and the mill capacity increased, it takes a g 'ater period of time to reduce the charge to ore parti. as of a predetermined size, and mill efficiency is therefore reduced. I The charge may be decreased in volume, which reduces the size of the kidney and comminutes the ore more quickly. However, with a reduced input of the charge, this necessarily limits the volume of ore partidcles to be discharged in a unit of time, and grinding efficiency is decreased in this manner.

1 11 1 l l l l l ll l l v l 1 1 1 1 1 1 1 1 1 1 ~:dL ii ~LIYIY13LII~ WO 86/04267 PCT/US86/00156 Summary of the Invention It has been found that, by configuring the liner assembly in a particular manner, activity within the charge can be increased with a commensurate decrease in the size of the kidney by breaking it up to an extent.

More specifically, this is accomplished by creating a plurality of ramp-like surfaces that extend circumferentially to present sequential steps to the ore charge as the shell rotates. Advantageously, the liner assembly includes a plurality of axial sections with each section defining its own sequence of ramp-like surfaces, and with the ramp-like surfaces staggered relatively from section to section.

Rotation of the mill is such that any given point in the charge which is disposed in engagement with the liner surface is moved progressively closer to the center of the drum as it travels up the ramp, but then abruptly steps radially outward at the end of one ramp and the beginning of another. It will be appreciated that, since this occurs over and over as the ramp moves, sequentially by the charge, the charge is "pulsed" at a rate which is a function of the effective circumferential length of the ramp and the rotational velocity ofI the shell.

It is the repeated impartation of "pulses" to the charge that produces directional physical forces and creates additional action within the kidney, thus serving to break it up. With the increased activity, there is a commensurate increase in total useful work done by the charge, resulting in increased grinding efficiency.

In addition to increased activity within the charge, the improved liner assembly can also result in secondary benefits of increased retention time' and WO 86/04267 PCT/US86/00156 -4segregation of the charge based on size. Both of these benefits further enhance performance of the mill.

Where a plurality of axial sections are used, we have found that variation in the circumferential position of the ramps of one section relative to those of adjacent sections "staggering" of the sections) will produce different desired results; e.g., retarding or advancing the rate of flow of the charge through the mill.

With the improved liner assembly, overall efficiency in terms of volume of reduced throughput per unit of time is increased. Because ore grinders are typically operated on a twenty-four hour per day basis, increased comminution efficiency results in significant economic advantages to the user.

Brief Dcnzription of the Drawings Figure 1 is an exemplary view of a portion o a liner assembly embodying the invention and insta ed in the shell of an ore grinding machine as view in a transverse sectional plane perpendicular to e axis of the cylindrical shell; Figure 2 is a reduced persp tive view which is schematic in nature showing a p rality of separate axial sections making up the in ntive liner assembly and the relationship of thes axial sections to each other; Figure 3 is view similar to Figure 2, and showing an alterna *ve relationship of the axial sections of the li r assembly; Fi re 4 is a view similar to Figures 2 and 3 showing other alternative relationship between the axial ections of the inventive liner assembly; Figure 5 is a generated fragmentary plan view l According to the present invention there is provided a machine for efficiently comminuting a charge of ore fragments, comprising: a cylindrical shell having a predetermined cylindrical axis; means for supporting the cylindrical shell for rotation about said cylindrical axis; a plurality of individual liner segments covering substantially the entire inner cylindrical surface of the shell; means for removably mounting the liner segments to the shell; the liner segments defining a plurality of ramp-like S surfaces that extend circumferentially and define sequential

S..

steps with the lowest point of one ramp-like surface adjacent the highest point of another; °and means for rotating the cylindrical shell in a oS.o S. direction so that the charge of ore fragments is caused to move relatively up each ramp-like surface to the next adjacent surface; the number of ramp-like surfaces and the circumferential length of each ramp-like surface being chosen to cause the charge of ore fragments to pulsate as the result of said relative movement up each ramp-like surface to the next adjacent surface.

The present invention also provides a method of comminuting ore, comprising: Seintroducing the ore into the cylindrical shell of an S ore mill, the cylindrical shell having on its inner surface a liner assembly comprising a plurality of liner segments disposed in an annular configuration and having a plurality of ramp-like surfaces extending circumferentially and defining sequential steps with the lowest point of one ramp-like surface adjacent the highest point of another; and rotating the cylindrical shell in a direction so that the ore fragments are caused to move relatively up each ramp-like surface to the next adjacent surface in a pulsating manner.

39 -4a- ~4 The present invention further provides an improved liner assembly adapted for use with the cylindrical shell of an ore grinding machine to efficiently comminute a charge of ore fragments, comprising: a plurality of individual liner segments adapted to cover substantially the entire inner cylindrical surface of the cylindrical shell; means for mounting the liner segments to the cylindrical shell; the liner segments being disposed generally in an annular configuration and comprising a plurality of ramp-like surfaces that extend circumferentially and define sequential Ssteps with the lowest point of one ramp-like surface adjacent o" the highest point of another; I: o each ramp-like surface itself being formed from a group of liner segments, with the liner segments within each group increasing substantially uniformly in thickness with the highest point of one segment adjacent and corresponding in thickness to the lowest point of the next segment; the number of ramp-like surfaces and the S, circumferential length of each ramp-like surface being chosen so that when in use, and upon rotation of the cylindrical 0 shell, the charge of ore fragments are pulsated as a result of relative movement of the ore charge up each ramp-like I surface to the next adjacent surface.

oe••o Brief Description of the DrawinQs 'c Figure 1 is an exemplary view of a portion of a liner •assembly embodying the invention and installed in the shell of an ore grinding machine as viewed in a transverse sectional plane perpendicular to the axis of the cylindrical shell; Figure 2 is a reduced perspective view which is schematic in nature showing a plurality of separate axial sections making up the inventive liner assembly and the relationship of these axial sections to each other; 39 -4b- 'AB Eu x Figure 3 is a view similar to Figure 2, and showing an alternative relationship of the axial sections of the liner assembly; Figure 4 is a view similar to Figures 2 and 3 showing another alternative relationship between the axial sections of the inventive liner assembly; Figure 5 is a generated fragmentary plan view of the specific structural configuration of a first embodiment of the inventive liner assembly; oo* o

S

39 -4-c- .1124Z7i WO 86/04267 PCT/US86/0015C Figure 6 is a sectional view taken along the line 6-6 of Figure Figure 7 is an enlarged fragmentary sectional view taken along the line 7-7 of Figure Figure 8 is a view similar to Figure 7 of a slightly modified version of the liner assembly shown in Figures 5-7; Figure 9 is an end sectional view of a second embodiment of the inventive liner assembly as installed in the shell of an ore grinding machine; Figure 10 is a generated fragmentary plan view of the second embodiment as viewed along the lines 10-10 of Figure 9; Figure 11 is a sectional view taken along the line 11-11 of Figure 10; and Figure 12 is an enlarged fragmentary sectional view taken along the line 12-12 of Figure 'Detailed Description of the Invention Figure 1 shows one of a plurality of axial sections of a liner assembly which is represented generally by the numeral 11. Each axial section comprises a plurality of individual liner segments which are installed in such a manner as to cover the entire inner circumferential surface of the cylindrical shell 12 of an ore grinding machine. One circumferential row of liner segments is shown in Figure 1. As will be discussed below, the liner segments also extend in axial rows within the cylindrical shell 12 so that substantially the entire inner cylindrical surface of the shell 12 is covered by the liner assembly 11.

In Figure 1, the individual liner segments are secured to the shell 12 by suitable means not shown, such as nut and bolt assemblies.

With continued reference to Figure 1, there are four different structural configurations of. liner WO 86/04267 PCT/US86/0156 -6segments used, which respectively bear the reference numerals 13-16. As is apparent in Figure 1, the primary difference between the segments 13-16 is in their thickness or radial height, and a description of the structural details of one segment will otherwise be exemplary of all of the segments.

Segment 16 has a bottom surface 16a that is slightly convex to correspond to the inner cylindrical surface of the shell 12, and a top or grinding surface 16b which defines two axially extending ridges which serve to carry particles of the ore charge upwardly for subsequent tumbling upon rotation of the shell 12 in the direction shown in Figure 1.

Liner segment 16 has sides 16c, 16d, with the latter having a greater thickness or radial height than the former. Accordingly, the thickness or radial height of the segment 16 increases gradually from the side 16c to the side 16d.

Each of the liner segments 13-16 is structured with the same gradual increase in thickness, and the segments are interrelated in size so that together, the four grinding surfaces of the segments 13-16 generally define a ramp-like surface, but with undulations as defined by the axially, extending ridges.

As shown in Figure 1, there are six groups of segments 13-16 extending circumferentially around the inner cylindrical surface of the shell 12, with the lowest point (the shortest side of segment 13) of one segment group disposed adjacent the highest point (side 16d of segment 16) of another segment group. As such, this defines a plurality of circumferentially extending sequential steps to which the ore charge is exposed as the shell 12 rotates. i While six groups of segments 13-16 are shown eii i 1 WO 86/04267 PCT/US86/00156 -7the number of groups is variable depending on the mill diameter and bolt hole pattern. With reference to Figure 2, it will be seen that, in the preferred embodiment, the liner assembly 11 comprises four individual sections lla-lld, each of which is structurally identical to the section shown in Figure 1. These axial sections lla-d are commonly centered on the rotational axis of shell 12 and are disposed in side-by-side relation.

Broadly speaking, each of the axial sections lla-d is annular in configuration, and as discussed in connection with Figure 1, each section defines a plurality of ramp-like surfaces that extend circumferentially and define sequential steps with the lowest point of one ramp-like surface adjacent the highest point of another.

Further, and as shown in Figure 2, the ramps of each axial section are cirpumferentially staggered with respect to the ramps of an adjacent axial section.

More particularly, and as shown in Figure 2, the axial section llb is staggered or advanced in the forward or clockwise direction (as viewed from the left end of the liner assembly 11) by a distance X. In the preferred embodiment this staggering is followed uniformly throughout the axial sections lla-lld, so that each of the sections llb-d is advanced by a distance of X relative to the section which immediately precedes it.

With reference to Figure 3, which shows an alternative form of staggering, the staggering distance between the adjacent sections lla-d is 2X in the forward direction, and this spacing is uniformly followed i throughout the liner sections.

IIn Figure 4, which represents another alternative, the distance of staggering is 3X in the forward direction, and in the preferred embodiment this staggering is also uniformly followed from section to WO 86/04267 PCT/US86/00156 -8section. This alternative may also be viewed as staggering each of the succeeding sections llb-d by a di;tance of X in the rearward direction, or counterclockwise as viewed from the left end of the liner assembly 11.

As will be discussed below, different handling of the ore charge is accomplished with different staggering arrangements, and other variations are possible to accomplish desired functions. The distance is based on the circumferential spacing of mounting holes in the cylindrical shell 12, and this distance is not critical. Neither is absolute uniformity of staggering between adjacent sections, although uniformity is preferred.

Figures 5-7 disclose a first specific structural embodiment of the liner segments of the inventive liner assembly. This liner assembly bears the general reference numeral 21, and in the generated plan view of Figure 5, three axial liner sections 21a-c are shown.

In this embodiment, the length the dimension extending in the direction of the rotational axis of shell 12) of the individual liner segments in liner sec- Stions 21a and 21c is the same, and the liner segments of section 21b are somewhat shorter. This dimensional variation may be carried out as one of several approaches to accommodating the liner segments to a particular mill, and demonstrates that the axial length of the liner segments in all of the axial sections 21a-21c need not be identical.

With additional reference to Figures 6 and 7, axial sections 21a and 21c are made up of three different individual liner segments 22-24, and axial section 21b is made up of individual liner segments 25-27.

Each of the segments 22-27 is secured to the cylindrical shell 12 by two or three conventional tapered head bolt r: i. :L ii surtace adjacent the highest point of another; and means for rotating the cylindrical shell in a direction so that the charge of ore fragments is caused to WO 86/04267 PCT/US86/00156 and nut assemblies that extend through mounting openings 29 in the individual segments and registering mounting openings 30 in the shell 12. As best appears in Figure the mounting openings 30 in the shell 12 are uniformly disposed in axial and circumferential rows, and the mounting openings 29 in the segments 22-27 must be appropriately disposed to register therewith. Also as shown in Figure 5, the cylindrical shell 12 of the preferred embodiment is provided with one or more "manhole" access openings 31. In the embodiment shown in Figure the access opening 31 is covered by one of the liner segments 26.

With specific reference to Figure 7, each of the liner segments 22 defines a bottom mounting surface 22a that is slightly convex to conform to the inner concave surface of the shell 12. Segment 22 further comprises unequal sides 22b, 22c that reflect the increasing thickness of the body of segment 22 from left to right as viewed in Figure 7.

Each of the segments 22 further comprises an upper or comminuting surface defined by axially extending, elevated ridges 22d, 22e, each of which has a rounded top. With reference to Figure 5, each of the segments 22 includes three spaced, colinear ridges 22d and 22e which are of different length and staggered relative to one another. The number of ridges 22d, 22e, and their length and spacing is not critical. Of importance is the performance of a lifting function to the ore particles as the shell 12 moves in the clockwise direction as shown in Figure 7.

With continued reference to Figure 7, each of the segments 23 also comprises a similar mounting sur- V face 23a, but which also includes axially extending recesses 23b, 23c facing the shell 12 that conserve material without affecting the strength and wearability I 1 1 11 11 WO 86/04267 PCT/US86/ 00156 of the segment 23. The recesses 23b, 23c are of graduated depth, corresponding to the increased thickness of the body of segment 23.

Segment 23 further comprises a short side 23d that is slightly greater in height or radial dimension than the adjacent side 22c of segment 22, and a long side 23e.

The top or comminuting surface is also defined by axially extending, elevated ridges 23f, 23g that, in the preferred embodiment, are structurally similar to the liner segments disclosed in the commonly owned U.S.

Patent No. 4,270,705, which issued on June 2, 1981 in the name of Darrell R. Larsen, and U.S. Patent No.

4,295,615, which issued on October 1981 in the name of James E. Mishek. Axially extending longitudinal channels 23h, 23i having closed ends and tapered sides that converge toward the mounting surface are formed in each segment 23. Inserts 23j, 23k are subsequently cast in the respective longitudinal channels. The resulting elevated ridges 23f, 23g are flat topped in this embodiment.

Alternatively, the longitucinal channels 23h, 23i may be open ended and extend over the entire length of the associated segment, and the inserts 23j, 23k may be of commensurate length and inserted by sliding in from one end thereof, as disclosed in U.S. Patent Nos.

4,270,705 and 4,295,615.

from a material which is softer and less brittle than thematerial of the inserts 23j, 23k, which are preferably cast from an extremely hard, long-wearing material such as martensitic white iron. Other materials are suitable.

The structural configuration of segment 24 is the same as that of segment 23 except for its thickness, 6b16b 116 d Si WO 86/04267 PCT/US86/00156 which increases from the largest radial dimension of segment 23.

Mounted together, the liner segments 22-24 define a ramp-like surface that increases in dimension from the shortest side of segment 22 to the longest side of segment 24, then stepping off to the short side of another segment 22 in a sequential manner.

With the exception of axial lengths and the number of axially extending elevated ridges, the liner i0 segments 25-27 have the same structure as the segments 22-24 as shown in Figure 7.

With specific reference to Figure 6, the ends of segments 22-27 are disposed in parallel, spaced relation. However, just above the inner surface of the shell 12, these mutually parallel sides diverge from each other in the direction of the shell 12, and define a pocket in which an insert 32 is retained. The function of the insert is to prevent the entry and compacting of ore particles between adjacent liner segments to the extent that removal of the segments for replacement purposes becomes extremely difficult.

In the preferred embodiment, the insert 32 is made of rubber and is generally triangular in configuration and dimensioned to be loosely retained within the pocket. Reference is made to the commonly assigned U.S. Patent No. 4,165,041 for further structural details and features of the insert and pocket.

In the preferred embodiment of liner assembly 21 as shown in Figure 5, the liner segments 25-27 of axial section 21b are advanced by a distance of one axial row of mounting openings 30 in the shell 12 by advancement of one axial row of mounting openings Liner assembly 21 thus generally conforms to the embodiment shown in Figure 2.

Figure 8 discloses a liner assembly 21' that WO 86/04267 PCT/US86/00156 -12-

I

is quite similar to liner assembly 21 with one variation. The individual segments 22', 23', 24' are different than their counterparts in liner assembly 21 in that each has a substantially constant thickness or radial dimension (aside from thickness variations due to the elevated ridges). However, the overall thickness of the segment body of liner segment 23' is greater than that of liner segment 22' and less than that of liner segment 24'. Consequently, each of the ramp-like sur- faces is defined by incremental steps. These steps do not adversely affect comminution and function in substantially the same manner as the elevated ridges themselves. I Liner assembly 21' offers certain advantages because the individual liner segments 22'-24' are symmetric. These include less difficulty in manufacture and reversability of the liner section within the shell when the leading edges of the elevated' ridges become worn.

Liner assembly 21' may also be configured to receive rubber inserts 32 in a similar manner to liner assembly 21.

Figures 9-12 disclose a second specific structural embodiment of a liner assembly 41 embodying the invention. Liner assembly 41 utilizes the general inventive concept of plural axial sections each of which defines a plurality of ramp-like surfaces that extend circumferentially in sequential steps. However, most of the liner segments of liner assembly 41 are of a composite rather than an integral structure. Consequently, and as best shown in Figures 9 and 12, a single wear cap 42 may be commonly utilized throughout the assembly 41.

With reference to Figure 10, liner assembly 41 comprises two circumferential rows 41a, 41b of liner segments that together comprise a single axial section; i L L- .y :iimics tne volume or ore particles to be discharged in a unit of time, and grinding efficiency is decreased in this manner. 4 WO 86/04267 PCT/US86/00156 -13there is no staggering of adjacent liner segments.

Each of the rows 41a, 41b comprises three liner segments represented generally by the numerals 43-45. As shown in Figures 10 and 11, the liner segments 43-45 are of the same length or axial dimension.

In addition, to compensate for the manhole access openings 31, each circumferential row 41a, 41b further comprises a liner segment 43' of reduced length.

The liner segment 43'' is sized to cover the manhole access opening 31 and fits between liner segments 43' as shown.

With reference to Figure 12, and as briefly discussed above, each of the liner segments 43-45 is of composite structure, comprising carrier or holder segments 43a-45a, respectively, with wear caps 42 respectively superimposed thereover. Each of the holder segments 43a-45a increases in thickness, with wear segment 4 3 a the lowest of the three. As shown in Figure 12, the increasing thicknesses of the holder segments i 43a-45a are dimensioned so that, with the wear caps 42 attached, a ramp-like surface is defined extending in the circumferential direction in sequential steps as I' described above.

To resist shear stresses on the mounting bolt assemblies (discussed below), and to resist relative movement, each of the wear caps 42 of the preferred embodiment is cast with three circular, downwardly projecting bosses 42a. As shown in Figure 10, the holder segment 43a is cast with three corresponding recesses 43b to receive the associated bosses 42a. As shown in Figures 11 and 12, registering mounting openings for mounting bolt assemblies 46 extend through the bosses 42a and recesses 43b. The mounting bolt of assembly 46 is a standard oval-head bolt that is recessed below the grinding surface of the wear cap 42 for protective purposes. The mounting bolt assemblies 46 commonly secure I C I I I. l L I '1I I I1 t- .U Or-- WO 86/04267 PCT/US86/00156 both the wear cap 42 and holder segment 43a to the cylindrical shell 12. The mounting arrangement of the holder segments 44a and 45a and their respective wear caps 42 is the same, although the mounting bolt assemblies 46 are somewhat longer due to the increased thickness of the holder segment bodies.

With reference to Figures 10 and 11, each of the holder segments 43a-45a is formed with four equidistantly spaced mounting openings. Liner segment 45 is exemplary, and these mounting openings bear the reference numeral 45c. The circular recesses register with three of these openings 45c to receive the associated bosses 42a. The mounting opening 45a for which there is no recess 45b receives a short bolt assembly 46 the head of which is recessed within this mounting opening, as shown in Figure 11. As such, one of the four mounting bolt assemblies 46 secures the holder segment 45a directly to the shell 12 independently of the associated wear cap 42, whereas the other three mounting bolt assemblies 46 extend through both the wear cap 42 and underlying holder segment 45a to commonly secure both to the shell 12.

The same mounting arrangement exists for all of the liner segments 43-45. With such construction, it is possible to remove the wear caps 42 for replacement without removing the underlying holder segments 43a-45a.

With continued reference to Figure 11, the opposed ends of adjacent wear caps 42 diverge toward the bottom or mounting surfaces to receive an insert 32. As exemplified by the holder segments 45a in Figure 11, the ends of the holder segments 4 3a-45a also diverge to receive an insert 32, such construction being similar to that shown in the embodiment of Figures 5-7.

With reference to Figures I0 and 12, the liner segment 43' is of single-piece construction, but has the I- WO 86/04267 PCT/US86100156 WO 86/04267 PCT/US86/00156 same thickness and grinding surface as liner segment 43.

Liner segment 43'' is also of single-piece construction, and aside from its shorter length, is otherwise structurally the same as liner segments 43'.

The composite approach to the liner segments 43-45 is advantageous in that the wear caps 42 and holder segments 43a-45a may be cast from different materials appropriate to their respective functions.

For example, the wear caps 42 are continuously and directly exposed to the ore comminution process, and in the preferred embodiment are cast from material having a high resistance to abrasion, such as martensitic white iron or martensitic steel. The holder segments 43a-45a are not directly exposed to the comminution process, and their primary function is to support the wear caps 42 in the ramp configuration. Consequently, they can be cast from a material which is less hard and less brittle, such as pearlitic chrome-molybdenum.

The composite approach and the mounting configuration also enable the wear caps 42 to be replaced when worn without replacement of the holder segments 43a-45a.

Summarizing, each of the embodiments disclosed utilizes a plurality of ramp-like surfaces extending circumferentially to present sequential steps to the ore charge as the shell rotates. The repeated impartation of "pulses" to the ore charge decrease the size of the kidney by breaking it up, increasing the total useful work done by the charge and grinding efficiency.

Claims (24)

1. A machine for efficiently comminuting a charge of ore fragments, comprising: a cylindrical shell having a predetermined cylindrical axis; means for supporting the cylindrical shell for rotation about said cylindrical axis; a plurality of individual liner segments covering substantially the entire inner cylindrical surface of the shell; means for removably mounting the liner segments to the shell; the liner segments defining a plurality of ramp-like surfaces that extend circumferentially and define sequential steps with the lowest point of one ramp-lik, surface adjacent the highest point of another; and means for rotating the cylindrical shell in a direction so that the charge of ore fragments is caused to move relatively up each ramp-like surface to the next adjacent surface; the number of ramp-like surfaces and the circumferential length of each ramp-like surface being chosen to cause the charge of ore fragments to pulsate as the result of said relative movement up each ramp-like Si..o* surface to the next adjacent surface.

2. The ore comminuting machine defined by claim i, wherein the liner segments are arranged in a plurality of axial sections commonly centered on the shell rotational axis and disposed in side-by-side relation, each axial section being annular in configuration and comprising a plurality of said ramp-like surfaces.

3. The ore comminuting machine defined by claim 2, wherein the ramp-like surfaces of each axial section are see. circumferentially staggered with respect to the ramp-like surfaces of an adjacent annular section.

4. The ore comminuting machine defined by any one of claims 1 to 3, wherein each ramp-like surface is itself S 39 -16- 39 -4c- 1124Z formed from a group of liner segments, the liner segments i within each group increasing substantially uniformly in thickness with the highest point of one segment adjacent and corresponding in thickness to the lowest point of the next segment.

The ore comminuting machine defined by either one of claims 3 or 4, wherein the circumferential staggering of the axial sections is uniform from section to section.

6. The ore comminuting machine defined by any one of claims 1 to 5, wherein the liner assembly is disposed so that a fresh charge of ore enters at one axial end and comminuted ore leaves at the other, and each axial section is circumferentially staggered by the same amount relative to the preceding axial section, and in the same circumferential direction.

7. The ore comminuting machine defined by any one of S claims 1 to 6, wherein the cylindrical shell includes a o plurality of mounting openings disposed in axially and circumferentially extending rows, and the mounting means comprising: a plurality of mounting openings formed in the e respective liner segments and disposed for selective o registration with the mounting openings of the cylindrical shell; o* and a plurality of mounting bolts sized to fit through the registered openings. S

8. The ore comminuting machine defined by claim 6 or claim S 7, wherein the circumferential direction of staggering is G clockwise as viewed from the axial inlet of the liner assembly.

9. The ore comminuting machine defined by claim 6 or claim 7, wherein the circumferential direction of staggering is counterclockwise as viewed from the axial inlet of the liner assembly.

The ore comminuting machine defined by any one of claims 1 to 9, wherein the respective liner segments are formed with elevated ridges that extend axially.

11. The ore comminuting machine defined by claim 39 -17- 0S 6 0 6 0 S. 0 B S wherein the elevated ridges are axially aligned from axial section to axial section.

12. The ore comminuting machine defined by claim 10 or claim 11, wherein at least part of the ridges comprise round-topped undulations.

13. The ore comminuting machine defined by any one of claims 10 to 12, wherein at least part of the ridges are flat topped.

14. The ore comminuting machine defined by any one of claims 1 to 13, wherein at least part of the liner segments are of composite structure, comprising: a holder segment secured to the cylindrical shell by the mounting means; and a wear segment carried by the holder segment.

15. The ore comminuting machine defined by claim 14, wherein the wear segments are of identical construction, and the holder segments are constructed and arranged to progressively elevate the wear segments to define said ramp-like surfaces.

16. The ore comminuting machine defined by claim 14 or claim 15, wherein the wear segments are formed from material e having a greater resistance to abrasion than that of the a holder segments.

17. The ore comminuting machine defined by any one of claims 14 to 16, wherein the wear segments are cast from a martinsitic alloy.

18. A method of comminuting ore, comprising: introducing the ore into the cylindrical shell of an ore mill, the cylindrical shell having on its inner surface a liner assembly comprising a plurality of liner segments disposed in an annular configuration and having a plurality of ramp-like surfaces extending circumferentially and defining sequential steps with the lowest point of one ramp-like surface adjacent the highest point of another; and rotating the cylindrical shell in a direction so that the ore fragments are caused to move relatively up each ramp-like surface to the next adjacent surface in a pulsating manner. 506 6 I 5506 -18- i -II YLUL-L -i-reU emooaiment, it will be appreciated that Li

19. An improved liner assembly adapted for use with the cylindrical shell of an ore grinding machine to efficiently comminute a charge of ore fragments, comprising: a plurality of individual liner segments adapted to cover substantially the entire inner cylindrical surface of the cylindrical shell; means for mounting the liner segments to the cylindrical shell; the liner segments being disposed generally in an annular configuration and comprising a plurality of ramp-like suLfaces that extend circumferentially and define sequential steps with the lowest point of one ramp-like surface adjacent the highest point of another; each ramp-like surface its. 'f being formed from a group of liner segments, with the liner segments within each group increasing substantially uniformly in thickness with the highest point of one segment adjacent and corresponding in thickness to the lowest point of the next segment; the number of ramp-like surfaces and the circumferential length of each ramp-like surface being chosen so that when in use, and upon rotation of the cylindrical oo shell, the charge of ore fragments are pulsated as a result of relative movement of the ore charge up each ramp-like surface to the next adjacent surface.

The liner assembly defined by claim 19, wherein the respective liner segments are formed with elevated ridges that extend axially.

21. The liner assembly defined by claim 20, wherein at least part of the ridges comprise round-topped undulations.

22. The liner assembly defined by claim 20 or claim 21, wherein at least part of the ridges are flat topped.

23. A machine according to claim 1, substantially as herein before described with reference to the accompanying drawings.

24. The method of claim 18, substantially as herein before described with reference to the accompanying -19- o -LILY cz-Lz uLI L.Lul. M Ly J- J-L.LUWtVU JL.L Ujil Zjt=t U.LUL1 UV I drawings. The liner assembly of claim 19, substantially as herein before described with reference to the accompanying drawings. DATED: 9 MAY, 1990 PHILLIPS ORMONDE FITZPATRICK Attorneys For: EVANS PRODUCTS COMPANY 0@30 *so. se 0 So 39