US3269668A - Ball mill with tensional and wear-resistant linings - Google Patents

Description

N. L.HALL.

Aug. 30, 1966 BALL MILL wmf TENsIoNAL AND wam-RESISTANT mames 5 Sheets-Sheet 1 Filed Nov. 27, 1963 Aug. 30, 1966 N. L. HALL.

VBALL MILL WITH TENSIONAL AND WEAR-RESISTANT L'ININGS Filed Nov. gv. 19s?.Y

3 Sheets-Sheet 2 INVENTOR. www

N. L. HALL Aug. 3o, 1961s 3,269,668 BALL MILL WITH TENSIONAL AND WEAR-RESSTAN' LININGS med Nov. 2v, 196s 3 Sheets-Sheet 3 Fig. 10,

a Af

United States Patent Olce 3,269,668 Patented August 30, 1966 3,269,668 BALL MILL WITH TENSIONAL AND WEAR- RESISTANT LININGS Newton L. Hall, P.0. Box 83, Zone 10, vSalt Lake City, .Utah Filed Nov. 27, 1963, Ser. No. 326,486 2 Claims. (Cl. 24l-137) This invention refers to the lining and associated parts.

which are applicable to cylindrical crushing or grinding mills used for the comminution or size reduction of rock, ores, or similar elements by breaking or grinding operations as employed for ore reduction.

The particular application as described in this sepcica- .The extended application of this type of mill may be used for the crushing, grinding or processing and finishing of ore or cement, other uses being for the mixing, classification, processing and finishing of chemicals, and the agglomerating or' pelletizing of granular substances for the extension of a processing treatment. The horizontal rotary mill has a wide application in the industries due to its practical shape, low upkeep, efiiciency of operation, and high capacity.

Ball mills are so termed in the trade when using balls as a grinding media in the mill load; rod mills when using rods or bars, and tube mills when using balls, or balls and rods in mills of several diameters in length of cylinder.

No definite dividing line exists in size reduction between the terms crushing and grinding. One is a term of violent compression, and the other is a compression extended to y* a microscopic state-the breaking of one part into two,

crushing into grinding. The division conforms to the trade parlance, an idiom of common speech.

Ball mills are in common use for fine grinding and may be of the horizontal rotary cylinder of uniform diameter or of the conical mill type and produce a product of over 200 mesh per square inch in screen size. Large size of balls of over four inch in diameter are used primarilyfor crushing in mills approximating ten feet in diameter, and balls of less than two inches in diameter are used for fine grinding.

The -collective weight of steel balls will average 300A pounds per cubic foot and combined with mill pulp, will increase the weight to 400 pounds per cubic foot. Grinding mills will average from 7 to 14 feet or more in diameter with ball mills of two diameters in length and tubev mills of gyratory or jaw type of Crusher and then pass the broken ore over a screen termed a grizzly or grate, and in turn delivering the undersize to a primary roll or disc capacity. The long rods are in axial alinement within the mill and turn diametrally of the rod in radial movement` of 5 to 15 feet, holding a mill feed of coarse or mine-run of rock to be crushed in a substantially vertical and free fall with the crushed ore passing over the mill load in an impact action upon the ore and rock at the load toe below.

Horizontal rotary grinding mills have mill cylinders which are necessarily involved with an enclosed load grinding element; of itself,l the rotating mill is a hollow cylinder which does not perform an effective service with` out the tumbling and rotating action of a contained grinding element, the combination of the mill cylinder as a unit with a grinding element as balls, rods, or diametral walls as another and contained unit to perform an eil'ective grinding result. The rotating mill cylinder combined with the active grinding elements comprise the mill and apparatus. Useless each without the other.

. Various grinding applications can be made for use of the ball type of mill. In the following application. the references used are for ore reduction.

Types of grinding mill are on the market wherein the mill casings and casing heads are lined with plates of alloyed steel to withstand the vigorous and rugged wear of the rotating mill load which is composed of hard steel lballs forming the grinding element of the mill load, the balls being made necessarily hard to fracture a hard or harder ore intermixed within the mill load. The mill action is severe, and necessarily so to create the impact ory grind required to pulverize the ore sufficiently for the liberation of the frequently microscopic mineral content in the ore. The milling action is an impact crushing force, and in the ball type of mill, the constant impelling action of the mill load with its contained load of balls or rods is an incessant battering of the mill load in rotating and cascading at rotations varying from l0 to 50 -rotations per minute, the rotations varying with the size of mill diameter. To withstand such a wearing action the interior lining of the 4mill casing and of other interior surfaces must be of an abrasion-resistant material equal to the abrading4 severity of the mill load. The mill and lining equipment must serve over an extended period of time to warrant the expense of milling operations of which the cost of reducing mine-run size of ore to concentrate size forms the chief item of expense. The ball mill is a sec-v ondary mill in the grinding circuit, such as; the mine-run of rock and ore must be reduced to screen size by the Crushers, jaw or gyratory so that the ball mill feed can act on the crushed ore and effect its pulverization to a powdered form, reduced in size of the mineral particle, ordinarily to a screen size of over 200 or finer mesh per square inch. Ball mills range in size from 7 to 16 feet in diameter and in mill lengths to 20 feet, the mill diameter and length of cylinder bear a relation to effect the desired size of mill product. The severity of the impact and cmshing actions within a rotating ball mill demands mill linings of alloyed steel composition to warrant the highv Crusher, and then to a primary ball mill, delivering the product to secondary ball mills using small balls for extreme fine grinding. Rod mills are of the same construction as ball mills and use steel rods or bars of substantially the length of the cylindrical mill interior. Steel rods are of diameters up to 4 inches and a mill load of rods may fill the mill almost to one-half of the volumetric mill heavy castings to remote locations where they are used. Constant improvements are being made in the quality of such steels with regard to their length of service in the field.

Liner castings are made to a man size for ease of installation and such castings are attached to the mill shell by bolting with the bolt holes being made through the mill shell with the inner face of the cast liner plate being formed to an undulating shape to provide a grip tothe mill loadv for its rotation. The texture of the load inrotation eliminates the necessity for a load lifter.'

A mill with a compartment wall feature has the load lifted by the compartment wall.

The protection provided by a shell lining to the mill cylindrical v casing is of utmost importance, for if the lining starts to fail and then permits the rotating load to attack the mill casing, a casing which is of soft steel and lacks the resisting qualities of a lining of alloyed steel, then a ruination of the shell can become apparent within a short time measured by a very few hours, vmaking a replacement in down time of plant operation serious. The cost of reducing the mine-run of rock to an almost impalpable powder forms the chief expense of operation in ore benefication.

The weight of rotating mill loads are measured in tons and the lining and wall structure must have a tensile strength to withstand the constant variation of weights and impacts which the falling loads develop. Hard iron castings are subject to fracture and liner castings of the mill shell require bolting attention, likewise the necessity for perforating the mill shell to hold the heavy liner castings forms an expense which can be eliminated, as shown in the herein specification.

Mill linings are of uniform thickness and of few parts per mill being successively installed through an opened trunnion or through a cylinder head opened by removal of either mill head. For an original mill construction, the mill lining or lining and compartment wall, may be installed within the mill cylinder at the place of manufacture intact, the ball mill being formed virtually complete and ready for installation on the foundations at the following place for use or operation.

In the following descriptions reference may be made to United States Letters Patent having been issued to the applicant herein: Patents Nos. 1,315,770, 2,580,541, and 2,653,769.

Objectives One of the objectives of this invention is, to incorporate within a grinding mill with shell lining or compartment wall members, a combination of structural elements possessing .inherent and residual tensile strength subject to milling stress and strain resistance, plus abrasion-resistant members of a composite character lling the open shapes ush with the web of the structural shape.

Another objective is to develop a milling action within a rotating mill cylinder which can accommodate a milling load of approximately 50 percent of the volumetric capacity of the mill cylinder, accept and crush a primary ballmill feed and produce a ground product which approximates a secondary mill feed, this objective being to effect the elimination of the primary mill and combining the primary and secondary mill within this objective.

Another objective is to concentrate the primary and secondary cost of equipment and operation such as time of circuit, economy of power, economy of mill oor space, elimination of down-time for replacements, and, production of an angular rather than a rounded or spherical shape of an individual particle of the finely ground product.

Another objective is to produce a crushing action on the mill load which will develop a greater percentage of angular crushed fines of a coarser screen size and offer a greater elimination of nes which effect slimes in the mill product.

A further objective is to provide a crushing action which conforms closely to a characteristic natural impact action of piece size reductioncrushing to grinding. f A further objective is to maintain a cascade or overfall of mill load surface action which is based upon the laws of gravity fall; this in point of crushing action upon the mill load.

Reference is made to the following drawings which form a part of these specifications and wherein similar reference characters refer to similar parts in all of the views:

' taken on line 3-3 of FIG. 1.

FIGURE l is a longitudinal and vertical section of a grinding mill with compartment wall taken on line 1-1 of FIG. 2 showing the compartment wall in position and wherein the mill shell or casing is noted by the numeral l with open cylinder heads 2a for the feed head and 2b for the discharge head.' The open head trunnion is noted as 3a at the feed head and 3b at the discharge head with the mill rotating on the bearings 3c at the feed head and 3d at the discharge head. The feed scoop 3e is attached to and rotated with the feed trunnion. At the feed end of the mill casing the driving gear 4 is attached driven by the driving pinion 5 from the drive shaft 6 (FIG. 2) which is operated by any suitable motive power.

FIGURE 2 is a cross section of the mill casing l holding a mill lining 7 formed of mill structural channels supporting a compartment wall `section 8 with open balancing space or slot 9, the spacing being provided by a channel segment 9a of FIG. 1. As events require the crescent lining mem-ber of FIG. 2 shown as 'structural steel channels may be substituted by crescent members of hard iron or cast steel. The compartment wall shown in section 8 of FIG. 2 is formed of structural steel as shown in FIGS. 6, 7, 8 and 9, with channel terminals as shown in FIG. 5.

FIGURE 3 is a longitudinal and vertical section of a grinding mill with compartment wall the section being The terminal sections of the compartment wall 8a are notched to a half section width to provide free space for widths of the two largest balls in use to avoid casting with protective coveringof the section. The balancing slot 9 of the compartment wall 8 is of a width greater than a 2 ball space, the slot being retained in width of spacing by the segment channel 9a being interrnediateto adjoining channel lining members 7.

FIGURE 4 is an enlarged cross section of a portion of the mill shell or casing with sections of the structural lining members as 7A, 7-B, and 7-C being shown in position to protect the mill casing under protection from action by vagrant mill loads. Section 7-B shows an advancing failure of the abrasion-resistant filling of the channel lining at 71 with the failure approaching the mill shell casing 1 at 7g. The protection afforded by the covering of the web plate of the channel lining provides an advance warning to the mill operator for -removal of the mill from service prior to an injury to the mill casing 'at 7g requiring a shut down from service of the mill rather than a replacement of the defective lining section 7-B. The mill channel sections as 7-A are filled with an abrasion-resistant element as 7e being reinforced in position between the channel flanges of each channel section as shown in sections 7A and 7-C. The abrasion-resistant filling element 7e may be of a suitable material which is non-shattering and of wearing qualities.

FIGURE 5 shows enlarged terminal portions of the compartment wall 8 in position between two opposite terminal portions of adjacent crescent liner sections, the terminal 7h being shown in section with the bearing =por tion against the terminal of the compartment wall being reinforced with a formed plate 7m welded to the channel section. The opposite channel liner 7j and basing plate is shown in elevation.

FIGURE 6 is an end view of an I beam shown in FIG. 7 showing the lines of flange torch cuts, A-A and B-B' being cut to the depths as noted in dash lines to be bent to the upper terminal and formed to the position C-C' andD-D'. The extended web portion E and F are cut to size as shown and replaced on the under side of the bent flanges and welded to join the extended flanges at CD' and form a support to the extended web L at C'D'. A similar modification is made at the lopposite terminal of the I beam wall section shown at FIG. 7.

FIGURE 7 is an abbreviated length of a wall section R shown in elevation, with the web plate shown extended as a unit of the I beam wall section, at L.

FIGURE 8 is a longitudinal section taken on line 8- 8 of FIG. 7, showing in abbreviated length a compartment wall section with plates E and F in under position -to the bent flanges at E' and F' and welded to position. lThe abrasion-resistant filling is shown in position covering and protecting the web of the I beam member.

FIGURE 9 is an under view of a completed wall sectionas shown in FIG. 7 with the anges being shown in position along lines B-B' and A-A and welded to the beam web at L.

FIGURES 10, 1l and 12 are diagrammatical views of liner rings in side elevation with FIG. 10 being of a circular lining, FIG. 1l of two crescent liners with compartment wall intervening, and FIG. 12 being of a circular lining and notched to accept the compartment wall and lugs.

I claim:

1. In a grinding mill, the combination with a rotary drum comprising; a cylindrical drum with an imperforate casing with open trunnion bearings having open casing Iheads positioned at each end of said drum, said casing provided with an interior structural steel channel lining .of high tensile strength with abrasion-resistant elements placed in thev open spaces between flanges of said lining channels, said interior lining having a plurality of circular lining members forming a composite ring or crescent lining curved to an inner circular radius of said casing, with the outer web surface of said channels facing and protecting the adjacent portion of said mill casing from vagrant loads and penetrating mill wear, said composite lining members supporting a composite diametral Wall formed of lstructural beams of high tensile strength with the open spaces between flanges being. filled with abrasion-resistant filling elements for wear protection, said wall and lining being mutual in support and independent of attachment to said casing, said wall being positioned in mill diametral and axial alignment anddividing said drum interior into two semicylindrical compartments ex- `tending along each side of said wall, said composite wall having a plurality of similar wall lengths with open spaces intervening the composite lengths, said spaces providing free access by gravity between said parallel compartments 'i i for ingress or egress of portions of said load during successive rotations of said grinding mill.

' 2. A combination as set forth in claim 1 wherein the mill casing is of uniform diameter and imperforate, with the interior casing lining comprising standard channel sec.l

References Cited by the Examiner UNITED STATES PATENTS 1,872,036 i 8/ 1932 Hardinge 241--182 X 2,580,541 1/ 1952 Hall 241--176 X; 2,653,769 9/ 1953 Hall 241-137 3,194,506 8/1965 Bourne A--- 241-182 X ROBERT C. RIORDON, Primary Examiner.

PEPPER, IR., Assistant Examiner.

Claims (1)

1. IN A GRINDING MILL, THE COMBINATION WITH A ROTARY DRUM COMPRISING; A CYLINDRICAL DRUM WITH AN IMPERFORATE CASING WITH OPEN TRUNNION BEARINGS HAVING OPEN CASING HEADS POSITIONED AT EACH END OF SAID DRUM, SAID CASING PROVIDED WITH AN INTERIOR STRUCTURAL STEEL CHANNEL LINING OF HIGH TENSILE STRENGTH WITH ABRASION-RESISTANT ELEMENTS PLACED IN THE OPEN SPACES BETWEEN FLANGES OF SAID LINING CHANNELS, SAID INTERIOR LINING HAVING A PLURALITY OF CIRCULAR LINING MEMBERS FORMING A COMPOSITE RING OR CRESCENT LINING CURVED TO AN INNER CIRCULAR RADIUS OF SAID CASING, WITH THE OUTER WEB SURFACE OF SAID CHANNELS FACING AND PROTECTING THE ADJACENT PORTION OF SAID MILL CASING FROM VAGRANT LOADS AND PENETRATING MILL WEAR, SAID COMPOSITE LINING MEMBERS SUPPORTING A COMPOSITE DIAMETRAL WALL FORMED OF STRUCTURAL BEAMS OF HIGH TENSILE STRENGTH WITH THE OPEN SPACES BETWEEN FLANGES BEING FILLED WITH ABRASION-RESISTANT FILLING ELEMENTS FOR WEAR PROTECTION, SAID WALL AND LINING BEING MUTUAL IN SUPPORT AND INDEPENDENT OF ATTACHMENT TO SAID CASING, SAID WALL BEING POSITIONED IN MILL DIAMETRAL AND AXIAL ALIGNMENT AND DIVIDING SAID DRUM INTERIOR INTO TWO SEMICYLINDRICAL COMPARTMENTS EXTENDING ALONG EACH SIDE OF SAID WALL, SAID COMPOSITE WALL HAVING A PLUALITY OF SIMILAR WALL LENGTHS WITH OPEN SPACES INTERVENING THE COMPOSITE LENGTHS, SAID SPACES PROVIDING FREE ACCESS BY GRAVITY BETWEEN SAID PARALLEL COMPARTMENTS FOR INGRESS OR EGRES OF PORTIONS SAID LOAD DURING SUC-NTS CESSIVE ROTATIONS OF SAID GRINDING MILL.

Images