US2405633A - Grinding mill - Google Patents

Description

Aug. i3, i946; L.. M. BARKER E'rAL GRI-NDING MILL Filed Jan. *13,* 1 9 l5:5

IN VEN TORS. .LNE MBAR/(Ear EATAN @Lew/S Patented Aug. 13, 1946 GRINDING MILL Lyle lVL. Barker and. Evan. G.. Lewis,l Ajo, Ariz., assignors. to Phelps Dodge Corporation New York; NL Y., a corporation AofiNew York Application January 13, 1943; Serialltlo..432,200.v`

This invention relates to grinding mills in which the commi-notion. of orel orY other material iseffected, by the grinding action of a massof moving balls, pebbles, or thelike, within arotating cylinder, and` in which thecomminuted-y materialis discharged-through a grated portion of the-cylinder. In. mills ofI this type the` pluggingV of the grate openings by worn grinding media, larger particles of ore, or the like constitutes afsource of considerable. annoyance, necessitates loss or operating time in repeated cleaning of the grates, and results in. substantial. diminutionl of mill capacity and eiilciency.

The prime object of thepresent inventionis to provide a grated discharge portion ofjagrinding millv which enables ready egress of ground materials, worn grinding meda, or other materials having certain maximum dimensionswithout the objectionable clogging tendencies exhibited in prior constructions. The invention provides a mill discharge end whichfulfills this. purpose in aparticularly simple. and eiectivemanner; and, which enables the advantagesof millsofY the type, mentioned. to be utilized fullywithoutinterferenceby objectionable plugging. of' thel discharge grates.

Other features andvadvantages ofthe invention, will be hereinafter. described. and claimed. y

In the accompanying drawing:

liig. 1. is a fragmentary elevation, as viewed from the inside, showing a. portion. of. the discharge end-of agrinding.milllembodyingoneform.

persons familiar with the art, we will describe.

particularly only thedischarge endof the mill..

Referring to the, drawing, 2 designates the cylindrical shell or main body portionof theigrind-- ing mill, and. 3 the head. which closesthe dischargeendv of said. shell. Secured to said` head 3 i's the customary centerpiece. 4.which, as shown,

may include a passage 5 servingV as. an. observa--v tion port and asa. point of addition of balls or other grinding media. Said centerpiece also has. formed therein a diversion passage. Ivfor the millproduct. Thev shell 2..is.provided.with a-lining 1 of suitable refractory material. At center end liner, which may be of. formand material: best adapted for grinding conditions, isindicated at: 8'; while other suitable end liners, disposed outwardly from saidliner', areshown at 9 andlll; Pulpli-fter` elements IIA of conventional fermA are also shown;

In carrying` outy our invention, We form discharge slots; such afsare shownat I2, by mounting elements- I3 of rubber'or other suitable resilient material inr suitably spaced` relationship. Inv the embodiment. illustrated; these resilient elements I3' are-fmoulntedI in7 cut out portions of the' liners 8, 9., andfIIl; and are attached to'and'i-lrmly mai-ntained inposition by backing plates Iwelded or otherwiselsuitably secured.- to said'liners or tothe dischargehead 3. As shown, said backing plates i4 terminate short of the edges` of thefrubber elements= I3 tot enable iiexurefof` saidedges-v tothe extent` desired. l'

We.Y furthermore, sofspace. theliners 8, 3, and Iwit-h respect toeachf other asto form between them channels |15-0f such width or formas to' permit:ready movement within saidchannels of the largestV ball, or other grinding member in the charge: The linersiwhich form-the' channel also functionftoprevent direct action of any large portionoii thecharge of grinding members upon the rubber elements I3.

It williV beiV understood that the cylinder '2, lining- 'I-, head 3., centerpiece= 4, liners 8, 9; and IIB, and lifters- I.I arefsuitablyY fastened together to ro*- tate in` unison inthe operationof the mill'.l The lif-ters Iltare integral,4 with the heade3, which is suitably secured tothey cylinder 2 and center-piece- 4.; while' the liners 83 8, and IUA andV associated backing plates i4? are suitably fastenedr to the li-fters-r II.

In assemblingl said liners andassociated parts, the liner I0- mayy first have attachedv thereto a rubber element I3 and aback-ingpla-te I4.. The latter may be fastened: toY the liner by suitable boltsorbywelding. Thereafter, said-liner II) may be. inserted intofthe. head 3 and secured therein by a suitably tight t, or by welding or otherwise fasteningy the backing plate I-@f tov the liftern II. Liner 8, after having a rubber element I 3- and backingplate I4 attached thereto may thenv be placed in the desired' position onY the lifters H and fastened..in. position through said plateV It. Said liner 8 may also,r asshown, have. a similar plate t4 interposedY between said liner 'and said lifter and suitably fastened.v thereto- Then. the liner9, after having,V rubber elements I3 andbacking, plate. Ill attached thereto; is placed. Von the litters I.I` inthe desired spaced. relationship with respect to? the. liners-8 and lill; following which said liner 9 is securedtmsaid litters III through said plate I4 in any desired manner. The cenprovide backing for the rubber elementsyIB by extending beyond the liners, but also that said plates, by terminating short of the edges 1 of said elements` provide for controlled exure of said.

edges. Said plates may be so positioned with respect to said edges as to control iiexure of the' latter to the desired extent.

A ball mill equipped with a discharge end em-v bodying our invention has been found to maintain full efliciency for a prolonged period, without interruption and without any evidence of plugging. The freedom from the necessity of periodic cleaning of grates, and the gains in capacity and eiiiciency resulting from lthe avoidance of grate clogging, are substantial and important advantages.

While we do not assert any particular Atheory as controlling or conclusive with respect to the advantages attained by our'inven'tion, WeV believe thatone vreason for the attainment of those advantages is the capability of the resilient elements I3 to dislodge, or feed back into the cylinder 2, oversize particles'which may become momentarily lodged between said elements. In that connection, it is to be noted that the width of the slot t2 between adjacent rubber elements I3 The backing plates I 4 may be Vof rigid material such as steel, or of material resilient and iiexible in character, such as conveyor belting.

The terms and expressions which We have employed are used as terms of description and not of limitation, and We have no intention, in the use of such terms and expressions, of excluding any equivalents of the features Vshown and described or portions thereof, but recognize that various modiiications are possible within the scope of the invention claimed.

We claim:

1. Grinding mill discharge means comprising members dening a channel, a plurality of resilient elements mounted on said members at the base of said channel and defining a slot, and backing means extending beyond said members over portions of said resilient elements and tersaid resilient elements, said backing means exis fixed only so long as said elements are not rubber, Vand its Walls are constantly parallel when in normal position. However, upon i'lexure of the rubber elements 'the width of the slot increases, and the walls diverge in the direction of deformation. Now, when a particle is presented ments I3, that particle can pass only if its minimum dimension is such that it'may enter the slot under the condition of maximum slot deformation. If the forces tending to move the particleA into the slot are not adequate for the purpose, the reiiex of the rubber elements rejects it when'the forces are removed. It is also pos-Y sible that particles of certain shane maybe temporarily retained in the slot and that the flexing and deformation of the rubber elements resulting from the subsequent entry of other particles accomplishes their release. But whatever may be the theory, We have found the construction illustrated to be highly effective in obviating clogging, with the consequent advantages hereinbefore referred to.

The elements I3 may be of rubber or any other material having the desired strength. flexibility, and resiliency. Fabric-reinforced rubber, conveyor-belt `cover stockrubber, orrthe so-called "iioating-stock rubber are examples of suitable materials which may be employed.

We believe also that the provision of channels I5 oiv such width or form asto permit ready movement within them of the largest ball, or other element in the grinding charge. augments the effectiveness of the invention by enabling grinding elements to act upon particles in the channels adjacent the'slots.

tending 'over portions of said elements but terminating short of the slot forming edges of said elements.H Y

3. Grinding mill discharge means comprising members defining a" channel in communication with the grinding chamber of the mill, said channel being of such form as to permit'free movement of grinding elements within it, resilient elements disposed at the base of said channel and defining a slot at said base, and backing means extending into overlapping relation with portions of said resilient elements and with portions of said channel, said backing means terminating short of the slot-dening edges of said elements.

4.,Discharge means for a grinding mill of the type comprising a rotatable casing providing a chamber for material to be ground, said discharge means comprising members defining a channel at a slot I2 and forced against the adjacent elefor` receiving material from said chamber, and means defining a slot at the discharge side of said channel, said means comprising a strip of resilient material secured at one edge to one of said channel-defining members, said strip having Aa substantial portion extending beyond said member and terminating in a free edge in said channel, said portion being freely movable inv a direction outwardly from said channel in response to pressure exertedthereon by material within said channel.

5. Discharge means for a grinding mill of the type comprising a rotatable casing providing a chamber for material to be ground, said discharge means comprising members defining a channel for receiving material from said chamber, and means defining a slot at the discharge side of said channel, said means comprising a pair of strips of resilient materialeach secured at one edge to aA corresponding one of said channel-denng members, each of said resilient strips having a substantial portion extending beyond the corresponding ychannel-delining member and terminatingin a free edge in said channel, each of said extending portions of said strips being freely mov. able in a direction outwardly from said channel in response to pressure exerted thereon by material within said channel. s

vE5. Discharge meansfor a grinding mill of the type comprising a rotatable casing providing a chamber for material to be ground, said discharge means comprising members defining a channel for receiving material from said chamber, said channel converging from its receiving side toward its discharge side, and means defining a slot at the discharge side of said channel, said means comprising a strip of resilient material secured at one edge to one of said channel-dening members, said strip having a substantial portion extending beyond said member and terminating in a free edge in said channel, said portion being freely movable in a direction outwardly from said channel in response to pressure exerted thereon by material within said channel, said channel being of sufficient size to enable free movement of grinding elements therewithin.

'7. Discharge means for a grinding mill of the type comprising a rotatable casing providing a chamber for material to be ground, said discharge means comprising members defining a channel for receiving material from said chamber, said channel converging from its receiving side toward its discharge side, and means defining a slot at the discharge side of said channe1, said means comprising a pair of strips of resilient material each secured at one edge to one of said channe1- deiining members, each of said strips having a substantial portion extending beyond the corresponding channel-dening member and terminating in a free edge in said channel, each of said extending portions of said strips being freely movable in a direction outwardly from said channel in response to pressure exerted thereon by material Within said channel, said channel being of such size as to enable free movement of grinding elements therewithin.

8. Discharge means for a grinding mill of the type comprising a rotatable casing providing a chamber for material to be ground, said discharge means comprising members dening a channel for receiving material from said chamber, and means defining a slot at the discharge side of said channe1, said means comprising a strip of resilient material secured at one edge to one of said channel-defining members, said strip having a substantial portion extending beyond said member and terminating in a free edge in said channel, and backing means extending beyond said channel-denning member over a portion of said strip and terminating short of said free edge, the portion of said strip beyond said backing member being freely movable in a direction outwardly from the channel in response to pressure exerted thereon by material Within said channel.

LYLE MQ'BARKER. EVAN G. LEWIS.

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