US2274331A - Tube mill lining - Google Patents

Description

Feb. 24, 1942. w. L. HowEs TUBE MILL LINING Filed Feb. 19, 1941 3 Sheets-Sheet 2 Patented Feb. 24, 1942 UNITED STATES PATENT OFFICE 2,274,331 TUBE MILL LINING Warren L. Howes, Tiger, Ariz. Application February 19, 1941, serial No. 379,725

17 Claims. 1 (ol. 83-9) 'Ihis invention relates to linings for tubemills and has as its object to provide an improved lifter arrangement whereby the useful life of the lining is considerably prolonged.

The linings contemplated und'er the present invention are formed with alternating valleys and lands, the following walls of the valleys constituting lifting surfaces. I have found that for the -best Wearing qualities the lands should be of sufficient Width to amply back the lifting ,sur-l faces, but that if the widthis excessive, slippage occurs between the disintegrating media and the abrasive action rapidly wearing down the latter. According to the present invention, the distance between successive lifters is made such that slippage of the disintegrating media is minimized, and, at the same time, adequate disintegrating action is secured. Other factors, such as the vform and depth of the valleys, conthe same form. Liners I5 and I6 together are of a length to extend throughout the length of the mill, as are also liners I1 and I8, and when the two sets are brought together in the manner shown in Figures 4 and 5, a break-joint relation will exist between them. As shown in Figure 3, the set, I'I, I8 reduces in thickness from the feed to the discharge end in order to take care of the greater wear adjacent the former. Liners I5 and I6 have the same taper as liners I'I and I8. Where the liners are of uniform thickness from end to end, two different sets as in Figures 1 and 2,are unnecessary, and liner I8 can be identical with liner I5 and liner I'I with liner I6. The illustrated liners individually have an arc of 36 so that five-of each are required for the complete lining of the cylindrical body. f course, the longitudinal sets may be made integral if desired, but ordinarily in a mill of subtribute to the improved result. 20

'I'he new linings areapplicable to the bodies of tube mills of cylindrical or conical formand also to the feed and discharge ends, and the disintegrating charge may be composed of usual media, such as balls or rods. of description I have shown in the accompanying drawings liner sections for a cylindrical ball mill and the description vwill proceed with reference to these drawings, in which:

Figure 1 shows in plan a pair of liner sections, in end to end relation, formed in accordance with the invention.

Figure 2 shows in plan a second pair of liner sections associablein break-joint relation with l those of Figure 1.

Figure 3 is a section on line 3-3 of Figure 2.

Figure 4 is a feed end elevation of the liners of Figures 1 and 2 in operative association.

Figure 5 is a discharge end elevation of the liners of Figures 1 and 2 in associated relation.

Figure 6 is a section on line 6---6 of Figure 2.

Figure 'itis an enlarged feed end view of one of the liners illustrating the manner of wear in-use.

Figure 8 is a face view of feed end liners in accordance with the invention.

Figure 9 is a section on line 9-9 of Figure 8.

Figure 10 is a section on line III- III of Figure 8, and

Figure 11 is a partial face view of a. modified form of end liner.

Referring first to Figures 1 to 7, reference numerals I5, I6, I'I and I8 designate liner sections in the form of concaves with their outer surfaces on the arcof the interior of the cylindrical body of the mill. These liners are all essentially of units. The liners may be of steel, rubber, silicious For the purpose stantial length it is more convenient to construct the liners in longitudinal sets of two or more or other suitable material.

Since except as to length and thickness, the liners are all of identical form, detailed description of one will suffice and reference will now be made in particular to liner I'I which appears n in each of Figures 2 to 7. l

Reference numeral I9 designates a valley extending throughout the hner II, the valley being of V-section with a substantially radial leading wall 20 and a following wall 2| at an angle of about to 60, and preferably not less than 45, to the wall 2p. At the sides of the valley I9 are lands or plateaus 22 and 23 which are of uniform width from end to end and may be flat or somewhat transversely concave. Near the bottom of the valley I 9 integral bridges 24 and 25 extend lbetween the valley walls and are centrally radially pierced to receive the Shanks and the oval heads of bolts as at 26, Figure 6, by means of which the liner is secured to the cylindrical drum 2I.y As here shown, the lands are provided with a series of longitudinally extending pockets 28 and 29 which extend radially from the inner face and' terminate short of the outer face. These pockets are provided particularly in the case of steel liners for the purpose of facilitating heat treatment. In any event, their provision substantially lightens the liner.

The leading edge of -linexl I 1 has a wall 30 relatively disposed as wall 2|, the wallv 30 terminating upwardly in the land 22 and downwardly in a more abruptly outwardly and forwardly inclined Wall 3I. Rearwardly, theliner has a substantially radial wall 32, like the wall 20, terminating upwardly at the trailing edge of land 23 and downwardly in a transversely curved bottom wall' portion 33 which runs intoa bottom wall portion 36 inclined substantially as the leading wall portion 3|. It follows that when the adjacent liner sections I5 and Il are brought together, the leading portion of the former forms with the trailing portion of the latter a valley 35 substantially identical with valley I9.V VSimilarly, the liner forwardly of liner I1 will form a valley having the wall 30 as its trailing bound.-

ary and all the valleys will be uniformly spacedv apart circumferentially of the drum.

The lines at which the trailing valley walls meet the succeeding lands I shall term points of lift and these points are designated by the reference character P. I have found that for best performance the distance between two adjacent points P should equal DX where D equals the average maximum transverse dimensions of the maximum sizes of disintegrating media and X equals a figure between 1.5 and 3.5 with the optimum value of about 2.4.

For optimum performance with the valleys shaped and disposed as shown, their maximum depth should not be substantially less than 0.25D or more than 1D with the best figure at about 0.6D. The width of the lands should be about equal to 1D and not substantially less than 0.5D, nor more than 1.5D. The maximum width of the valleys should be about 1.25D and not substantially less than 1D nor more than 2D. The transverse, angle of the valleys should not be substantially less than 451 or the distintegrating media may wedge.

In a typical installation, in a mill five feet in 9. The sections are provided with alternate radial valleys and lands 39 and 40 whose inner faces are arcuately convex radially as particularly shown in Figure 9. The valleys are angular as before and preferably their maximum transverse dimension at the periphery is the same as that of the body liner valleys. In the completed installation the valleys and lands of the body lining preferably register at their ends with the outer ends of the valleys and lands, respectively, of the end liner or liners. The lands are flattened at their outer ends as at 4I to accommodate the ends of the lbody liners. Reference numeral 42 designates bolt holes formed in the trailing walls of the valleys adjacent and partly in the leading portions of the lands. Reference numerals 43 and 44 designate radially extending pockets in the trailing walls of the valleys at the leading edges of the lands. Other bolt holes as at 45 may be formed at the bottoms of the valleys partly in the trailing portions of the lands. The valleys and lands taper laterally toward the opening 33, as shown.

Where the end linings are of considerable diameter, the lands and valleys may be formed in concentric series 46 and 4l as shown in Figure l1. In this manner extreme tapering is avoided.

In Figure ll the valleys are indicated at 48 and diameter and ten feet long, rotating at 27.5

R. P. M. with a maximum ball size of four inch diameter and with liners of manganese steel, the following dimensions, in original installation, will be appropriate:

Thickness of linerT inches 31/2 to 41A Distance between points of lift do 91/2 Valley angle degrees-- 55 to 60 Valley depth inches-- 21/2 to 2% Maximum valley width do 51A Since in this case the factor D is four inches it will be seen that X is something over two.

In Figure '7 the progressive wear in such an installation is indicated by the lines a to f, the 'latter indicating the condition of the liner when substantially worn out. In this case the points of lift P have migrated to the points P' which are spaced apart substantially the same as the points P. It will be seen that the dot and dash lines which indicate the paths of migration do not intersect the original valley outline, but on the contrary terminate beneath the latter. I f the lands were of substantially sm-aller width the lines of migration would intersect the radial` walls 20 and 32 and the resultant peaks, no lands being now present, would peen over and break oil?. Hence, the importance of amply backing the lifting surfaces.

Referring now to Figures 8, 9 and 10, reference numerals 36 and 31 designate two end wall liner sections each having the outline of a 90 sector of a circle with its apex arcuately removed so that with the addition of two further similar sectors a circular feed or discharge' opening 38 for material will be provided. Actually, as here contemplated, the end liner is in the form of a fiat frustum of a cone as is evident from Figure the lands at 49 in the outer series, and at 50 and 5| in the inner series. It will be evident that the outer ends of the v.lands and valleys of each series can have the same width, which may be the same as the widths of the valleys and lands of the body liners.

In the case of conical liner sections, the lower limit of the factor X may be somewhat less than that preferred in cylindrical liner sections. For the conical liners the preferred limits of X may be from 0.75 to 3.5.

The factor D has been stated to be the average of the maximum transverse dimensions (diameters in the case of balls or rods) of the maximum sizes of the disintegrating media. Where there is a preponderance of the maximum size, as was assumed in the example given above, it is suflicient for all practical purposes to give D the maximum value without averaging in the proximate sizes. In the example given, D took the value of 4, the diameter in inches of the largest size balls of the charge, the distance P-P being therefore the number of inches determined by the value selected for X.

'Ihe value X is proportionate to the depth, which I will designate II,of the valleys. As has been stated, P-P equals DX. Therefore, P-P

lands and V is the maximum width of the valleys,

i. e. the` width at the valley tops. It follows that DX equals T plus V and that X equals T plus V divided by D. T is proportionate to H and V is proportionate to the valley angle, which I will designate B. Therefore, `where B is a constant, X is proportionate to H. The determination of the latter depends on the compromise that is reached between the effectiveness in casting liners of various thicknesses and the sacrifice that can be made in using up mill volume (and thereby mill capacity) with thick liners. The valley angle depends upon the desired mill speed and action of the disintegrating media.

The invention is, of course, susceptible of variation as to the form and arrangement of the lands and valleys and as to relative dimensions. While rectilinear lands and valleys have been shown, they might of course be spiral or otherwise conformed. I do not limit myself in these 'respects except as in the following claims.

' I claim:

1. A tube mill comprising a lining and grinding media of substantially circular cross-section' therein; said lining being formed with alternate valleys and lands providing lifters and vbeing de- -signed with reference to the size of the grinding media, for the purpose of reducing' lining wear, as follows: the distance between theA points of lift is substantially equal to DX, where D is the more than'D; and the width 'of the lands is not substantially less than 0.5D, nor more-than 1.5D. 2. Apparatus according to claim 1 wherein the llining is a bodylining and is constituted by concaves along which the lifters extend with substantially runiform spacing throughout.

3. Apparatus according to claim 1 wherein the lining is an end lining, whereinthe lifters are radially arranged, wherein the distance DX exists at the periphery of the lining and the distance between the points of lift of adjacent lifters decreases inwardly, and wherein the said vally depth and land width exist at the periphery of the lining.

4. A tube mill comprises a lining and grinding media of substantially circular cross-section therein; said lining being formed with alternate valleys and lands providing lifters and being designed with reference to the size of the grinding media, for the purpose of reducing lining wear, as follows: the distance between the leading edges of adjacent lands is substantially equal 'to DX, where D is the diameter of the maximum size of grinding-media used preponderantly to .maintain the charge and X is a iigure between 1.5

maximum width of the valleys is not substantherein; s'aid lining being formed with 'alternate valleys and lands providing lifters and being designed with reference to the size ofthe grinding media', for the purpose of reducing lining wear, as follows: the distance between the leading edges of adjacent lands is substantially equal to DX, where D is the diameter of the maximum size of grinding media used preponderantly to maintain the charge and X is a figure between 1.5 and 3.5; the depth of the valleys is notsubstantially less than 0.25D nor more than D; the val- 'leys are of substantially' V-section with their trailing walls inclined inwardly and rearwardly; an'd the width of the lands is not substantially less than 0.5D nor more than 1.5D.

9. Apparatus according to `claim 8 wherein the trailing walls of the valleys are at an unile of from about to 60.

10. Apparatus according to claim 8 wherein the trailing walls of the valleys are at an angle l of from' about 45 to 60 and their leading walls are substantially radial. v

11. A tube mill comprising a vlining and grinding media of substantially circular cross-section therein, said lining being formed with alternate valleys and lands providing lifters and being designed with reference to the size of thegrinding media for the purpose of reducing lining wear, as follows: the distance between the leading edges of adjacent lands is about two and onehalf times the diameter of the maximum size of grinding media. used preponderantly to maintain the charge, the Width of the lands is about the same as the said diameter, the valleys are of substantially V-section with theirv trailing walls inclined inwardly and` rearwardly, and the Valley depth is about six tenths of said diameter.

12. A tube mill liner section in the form of a concave having an axially extending valley and front and rear lands extending along the edges of the valley, the valley being defined by front and rear walls in V-relationship .with the rear wall inclined rearwardly from'the radial and joining the rear land at a point of lift, said vliner having a front wall also inclined rearwardly' from the radial and joining the front land at a point of lift, the lands being of substantially equal width and the width of eachland to the width of the valley being substantially in the ratio of 4to 5, the width ofthe valley being substantially twice its depth, said liner having a rear wall disposed to the radial substantially as the front valley wall so that said front and rear liner walls are adapted to form similar valleys with adjacently disposed similar liner sections.

13. Apparatus according to claim 12 wherein the inclination of the rear valley wall is at an angle of from about 45 to 60.

.14. Apparatus according to claim 12 wherein the inclination of the re'ar valley wall is at an angle of from about 45 to 60 and the front wall is substantially radial.

15. A tube mill liner section intheform of a segment having a radially extending valley and front and rear lands extending along 'the edges of the ,valley, the valley being defined by front and rear walls in V-relationship with the rear wall inclined rearwardly and joining the rear land at a point of lift, said liner having av front wall also inclined-rearwardly from the radialand joining the front land at a pointpf lift, the lands being of similar width and they and the valley tapering in width from the large toward the small end of the segment, the width 'of each land to .the width of the valley beingsubstantially in the ratio of 4 to 5 and the width of the valley at the large end'of the segment being substantially twice its depth, said liner having a rear wall disposed to the radial substantially as .the front valley wall so that said front and-rear liner walls are adapted to form similar valleys with'v adjacently disposed similar liner sections; A y

16. Apparatus according -to claim 15 wherein the inclination of the rear v ey wall is at an angle of from about 45 to 60. 4

17. Apparatus according to claim 15 wherein the inclination of the rear valleywall is at an angle of from about 45 to-60 and the front wall is substantially radial.

. p WARREN L. HOWES.

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