US1090933A - Mining-screen. - Google Patents

Description

H. Ai MEGRAW.

A MNING SCREEN. APPL'I'IO FILED MAY l, 191.

gmg, Patented Mar. 24, 1914.

2 BEEBTS*SHEBT 1` Mimmo@ H. A. MEGRAW.

MINING SCREEN.

APPLIGATION FILED MAY 1, 1913.

` 1,090,933; Patented Mar. 24, 1914.

2 SHEETS-SHEET 2.

HERBERT A. ivriaGnAiv,

'or NEW YORK, N. Y.

MINING-SCREEN.

Specification of Letters Patent. Application filed May 1, 1913.

Patented Mar.. 24h lisier.. Serial N 0. 764,787.

To c/ZZ Awhom it may concern Be it known that I, HERBERT A. MEGRAW, a citizen of the United States, and a resident of the borough of Manhattan, in the city, county, and State of New York, have invented certain new and useful Improvements in Mining-Screens, of which the following is a specification.

In the Wet metallurgy of various metals, including gold, silver, copper, lead, zinc and some of the less important minerals, it is necessary to separate the ground rock or ore into classes according to their sizes in order that the different classes or sizes may receive different treatment. After apreliminary crushing some of the rock may be reduced to 'the desired degree of lineness While another pa'rt will be in sizes too large to be efficiently treated bythe particular process in view. It is then necessary to separat-e the iinely ground portion from that which is not sufficiently fine, so thattlie latter may receive further grinding. Orit mayA be that each class or size of material requires diflferent metallurgical handling, as is the case in concentration, Where each size should be separately 4Worked upon, or in ,cyanidatiom where the fine portion must be treated in one Way" and the coarse portion in an en-v tirely different manner.- This separa-tion has been accomplished in different Ways, more particularly by screens or sieves of which many forms have been in use, butnone of which has given. entire satisfaction. The requirements of a satisfactory screen which the present invention ailns to fulfil are: durability and strength of construction, capacity to handle a large amount of material quickly, avoidance of blockading o r filling of the screen, small power requirement, mininium requirement in respect cfg-rade or height in installation, and convenience, efficiency and economy in leading the material to and away it'roni the screen.

A primary object is the a voidance ofivear, not only of the screenas a Whole, but more particularly olf' the screen fabric itself, thus especially fitting the invention for line screening, for which the fabric is frequently of great delicacy and therefore peculiarlv subject to Wear, particles of ore and from the movement or n'iovements'imparted to the screen. In my screen the action of' the ore particles is minimized and the movement of the screen both from the action of the' is simply one of rotation, without vibration or bumping or bending of the Wire mesh.

sizing screens for Heretoi'ore in rotary ore line screening wear has been very rapid and has been very diilicult to keep the meshes from becoming clogged, because the sliding ot the ore on the fabric is not only iminediately destructive but multiplies the opportunities for blockading, to relieve' which latter condition agitation or vibration or disturbance oi" the screen and fabric of some sort has been resorted to, with the result of greatly hastening their destruction. According to my invention, the sliding of the ore on the fabric is limited by means in the nature of shelves, which also serve to remove the over-size material from the screening region. the organization being such that successive portions of the pulp are in effect deposited gently upon a succession of screens, the under-size being permitted to pass through at once and the over-size being carried ifi retard. The screen is tubular or elongated and is rotatably supported near its @nds of: at suitably spaced points by bearings. such as rollers, which leave its interior and ends unobstructed; the pulp is led in at one end and deposited upon and length` wisc of e' he bottom of the screen by an entry laundeV adjacent the lowest part of the screen; id the over-size is carried onward in the salue direction by an over-size discharge launder to which the material Which does not pass through the meshes is elevated and v delivered by the longitudinal wear-preventing shelves. The fact that the entry and over-size launders extend in the same direction, adapt-ing the screen for through-movement of the material, in at one end and out at. the other, though not along the bottom of thc screen, essentially distinguishes this screen from any construction which requires the pulp to double upon its track. My screen provides for direct travel of the ore pulp, without manual or mechanical effort, Without special elevating machinery, and Without additional Wear and loss of grade due to turns or angles in the launders, and is adapted to make the most advantageous use of natural grade, or to require the least amount of articial'grade or heightJ in installation.

In the drawings: Figure l is a vertical longitudinal section; Fig. 2 is a vertical cross-section on the line 2-2 ot'Eig l; Fig.

Y constructed bysupporting the screen material 11m; a frame or skeleton structure consisting of end ring castings .12 and con- 4neetin'g members 13, which may be in the nature of angle irons as shown. The screening medium is curved around the members 13, and its longitudinaledges are desirably clamped as indicated in Fig. 5. Manifestly the screen material may be secured to the support-ing structure intermediate these edges it' desired, and while it is shown brought into cylindrical tubular form it will be understood that it might be polygonal in cross-section with equivalent results.

The invention is designed for line screening, for which a wire fabric is employed, which may vary from 4l to 100 mesh, or

smaller, according to the iineness of the ma' terial to be sized.

The sieve thus constructed is supported on bearings which leave both its ends and. its interior unobstructed, this being important for the purposes of my invention. Thus, the ring castings l2 are shown provided with tracks lll which rest on grooved rollers 15 mounted on blocks 16, at opposite ends of the sieve. Driving of the screen is advantageously provided for by means of a Worin 17 at the top, which meshes with a worm gear 18 formed on one of the ring castings outside of the track flange 14, where the gearing is largely protected from dirt and moisture. The sieve is supported substantially horizontal, and the pulp does -not travel len hwise over its bottom.

Interiory the sieve has provisions for limiting the lateral sliding of the material, which consisting of ground rock and particles oi metal is naturally abrasive, and for elevating the oversize material. which does not pass through the meshes of the screening medium, loi' the purpose presently to be described. The simplest form of these provisions is that indicated, consisting of flat shelves or inward proj ecting wings 19, which are shown secured to the angle irons 13, though obviously they might be integral therewith so as to form elongated flanges of the angle irons. The spacing of these shelves and their Width. or depth will obvif ously depend upon the special conditions of each case; but in general the distance measured circumferentially between them on the screen material should be such as to reduce as much as possible the sliding and rolling of the particles, so as to minimize the wear on the medium, While at the saine time permitting such range of movement as may be necessary to insure effective separation; The y shelves extend the full length of the sieve or substantially so, and carry up the larger particles of the pulp, which is distributed the fulllength of the bottom of the sieve by the means now to be described.

The material is supplied to the screen, substantially equally throughout its* length, by means of an entry launder or trough 20, which enters the screen at one end and extends substantially the full length thereof, in the lower part and preferably centrally of the screen. This launder leads from any suitable source of supply and is suitably pitched, according tothe rate of flow desired and the consistency of the fluid mixture of ground ore and water. It is preferably elosed vat'its lower end and is provided with suitable means for causing the material to overflow or discharge substantially equally at different points along its length. As shown it has a multiplicity of discharge openings 21 arranged in longitudinal series along one side and adjacent its bottom, and with these openings are associated a number of vanes 22 in the interior of the trough, the same being` mounted so that they can be turned more or less and in dili'erent degrees to secure the exact distribution desired. One

such directing device is shown for each opening, but obviously feuer could be employed. Any suitable provision may be made for holding the angular adjustment of the vanes 22. For example, they may be pivoted on ordinary wood screws 2S. which are screwed into the -bottom ot' the entry launder and may be readily tightened or loosened.

A discharge launder Q3 is located above the entry launder, and likewise extends the full length of the sieve. It is inclined in the sanie direction as the entry launder. so as to lead the oversize material out at the end opposite to that at which the entry launder leads the material in. Its lower projecting portion is shown broken away to indicate that it may extend to any suitable distance or point of discharge. At its upper end also it preferably extends beyond the entry end of the screen, for the purpose oi atiording means for supplying the discharge laun der with a special or additional current of Water when desired to insure the washing away of the oversize. This portion of the discharge launder is also shown broken away, because it may lead troni any point.

The interior of the sieve being unobstructed, this launder, aswell as the entry launder, can be located in the most advantageous positions. Thus, as to the discharge launder, it is desirable'to locate it so that its .upper side edges are adjacent the horizontal `tire shelves deliver .ward and downward of the inner edges the oversize material directly to this launder practically Without any spilling back into the lower part of the "'siVeTli,discharge launder is quite broad,

and by virtue of the construction and mode of support of the sieve itmay be made as deep may be found advisable to avoid any danger of overflowing in event of a copious amount of wash water being employed. The form of the discharge launder may naturally be varied, but a desirable shape is the one illustrated, which lends itself well to sheet metal construction and in which the side portions of the trough simply slope intoward the center part, which may be curved.

The launders are shown'supported on uprights 24, outside the ends of the sieve, but it will be understood that these are .i merely indicative o-f any suitable means of support. C'

travels directly downward and fo ln order to prevent the blocladingvof the screening' medium by particles which are too -large 'to pass through but large enough to become caught in the openings, (this having been aserious problem in mining screens), I provide means for supplying water to the top of the sieve, so as to wash such particles back, into the discharge launder. To thil end I have shown two water pipes 25 eX- tending longitudinally over the top at opposite sides of thecenter, these pipes being perforated so as to deliver the water downward in jets of4 suitable size. The water in the pipes being under appropriate head or pressure, a very effective clearing action is secured. This wash water falls into the discharge launder and serves to carry away the oversize material, in which it may be assisted by water supplied at the upper end of the launder; or the major portion of the water flowing in the discharge launder may come from beyond theentry end of the sieve, so that the oversize material is in effect deposited into and washed away by a stream of water iiowinginto and through the sieve.

The undersize material is received in a vessel 26, which is located beneath the sieve and comes up far enough on the sides thereof to catch lall the material that passes through ,the meshes of the screening mcdium.'` It preferably slopes toward the discharge end o-f the sieve, and is provided with a dischargespout or pipe 27, which leads to any suitable pointi It will be seen that all of the material has a substantially vdirect travel to and away from the screen. The pulp enters -atfrme end, `the under-size passes through the mesh of the screen yand fwaro", and the over-size is elevated slightly and also continues in the saine general direction.

In operation, the ground oreand water flew into the sieve lthrough the entry launder of the shelves 19, so that so that the separation is effected `material enters the and are distributed throughout the length of the tube. The mixture contains a sufficiently large amount of water and the particles of rock and mineral are loose, that is to say not of a sticky or adhesive consistency, quickly and thoroughly when the material encounters the screening medium; but the hard particles, particularly those `which are too large to pass through, would tend to roll or slide on the surface of the fabric, thereby causing` wear, and it. is an .important advantage to be able to minimize this action, and to limit the opportunity of slightly oversize particles to becomecaught in the meshes, by means of the elevating or rupting devices projecting from the inner surface of the wire screen. By these latter devices the oversize material is carried up and deposited in the discharge launder,

where it is carried away by the iiow `of water'es described. As successive portions ofl the screen reach the topthey are automatically-cleared of bloekading particles by the jets from the overhead pipes. It will be observed that the oversize material is carried away at or above the level at which the screen, so that there is no loss of vertical height, which 'is-frequently a matter of great importance in mill design. The entry launder and the undersize discharge may be brought even closer to the same level than shown, so that there need be little loss of vert-ical height as to this part of the material. t will be observed that tho entering material passes into and thel oversize material passes out of the screen in the same direction, and that the arrangement of the launders `is such as to secure the greatest convenience and economy in construction and operation. lt isv importantthat the means for delivering the pulp to the sieve be located in' the lower part thereof and close to the screen fabric,

so as to minimize the fall and thereby contribute to the general object of avoiding wear.

(,)bviously numerous changes may be made in the construction of the screen without departing from the substance of the invention. rlhe tubular or elongated form of the screen 'enables it to handle a considerable amount of material in a short space of time, and to increase the efficiency it may be made longer than shown. The size of the mesh of the screening medium is somewhat exaggerated in the drawing, for convenience of illustration. An obvious adaptation of the invention would be-ito unite a number of the sieves in axial alinement Vith screening inediums ol .progressively liner mesh, the .discharge launder of each delivering to the sieve next in series.

What I claim as new'is:

l. An ore-sizing screen, comprising, in

intercombination, a non-vibratory rotary-tubular sieve supported to rotate on bearings which leave its interior and ends substantially unobstructed, means for conducting ore pulp and distributing it lengthwise of the sieve,

said means entering at one end and extending longitudinally of the sieve adjacent the lower portion thereof, an over-size launder at a greater height in the interior of the sieve extending lengthwise thereof and inclining toward the opposite end from that at which the pulp enters, and means in the nature of shelves on the inside of the screen to limit the sliding of the ore and to elevate the oversize material and dump it into the over-size launder.

2. An ore-sizing screen, comprising in combination a rotatably mounted tubular sieve open at the ends and interiorly so as to afford passageway therethrough for the over-size material, an entry launder extending i'tr'at one end of the sieve, an oversize lannder above the entry launder and in- /clined toward the opposite end of the sieve,

,25 /sdasto carry the over-size material onward f-`( in ,the ,same direction, and means comprising Vshelves on theinside of the sieve adaptedto limit the sliding of the ore thereon and to elevate the over-size material and to dump it into the over-size launder.

An ore-sizing screen,v .comprising in ccmbination a rotatably mounted tubular sieve open at the ends and interiorly so as to afford passageway therethrough for the oversize material, means for conducting ore pulp in at one end of the sieve and for delivering it to thel screen fabric throughout the length thereof, an over-size launder above said means and inclined towardhe opposite end of thesieve so as to carry the over-size material onward in the same direction, meansy compris1ng-shelves on the inside of the sieve adapted to limit the sliding of thefore thereon and to elevate the over size material and to dump it into the oversize launder, and means for applying a spray externally to the top of the sieve above the over-size launder.

4. An ore-sizing screen, comprising in sieve open at the ends and interiorly so as to afford passageway therethrough for the over-size material, an entry launder extending in at one end of the sieve, an oversize launder above the entry `launder and inclined toward the opposite end 'of the sieve so as to carry the over-size material onward in the same direction, means comprising shelves on the inside of the sieve adapted to limit the sliding` of the ore thereon and to elevatethe over-size material and to dump v 'combin at1on,a non-vlbratory it into the over-size launder, and means for supplying liquid to the over-size launder to wash away the oversize material.

An ore-sizing screen, comprising in combination a rotatably mounted tubular over-size launders; extending combination a rotatably mounted tubular sieve open at the ends and interiorly so as to afford passageway 'therethrough for the over-size material, an inclined entry launderV entering and extending lengthwise of the lower part of the sieve and provided with means for uniformly distributing the material throughout the length ofthe screen,l an over-size launder also extending lengthl wise of the screemat a greater elevation than the entry launder, and inclined in the same direction, and mear 's' comprising shelves on the inside of the si -ve adapted to limit the sliding of the ore thereon and to elevate the over-size material and to dump it into the so.V over-size launder.

6. An ore-sizing screen, comprising in combination a rotatably mounted tubular sieve open at the ends and vinteriorly so asV to attord passageway therethrough for the 35' over-size material, an inclined entry launder entering' and extending lengthwise of the lower part of the sieve, an over-size launder also extending lengthwise of the screen,=at a A greater eleva tion than the entry laiinder, and '90 inclined in the same directionbmeans beneath the screen for receiving't-heunderfsize "material and conduct-ing it onward ixr the same direction, and means shelves on the inside of the sieve limit the sliding of the ore thereon and to elevate the over-size material and to dump it into the over-size launder.

7. An ore-sizing screen, K combination a rotatably mounted tubular sieve open at the ends and interiorly so jas to afford passageway therethrough foi-'fthe oser-size material, an inclined entry lati!idlery entering and yextending lengthwise f'of'-tli lower part of the sieve, an over-size laundejgg also extending Ylengthwise of the screen, at a greater elevation than the entry launder, and inclined in the same direction,an undersize receptacle beneath the screen slopingforward and downward' to discharge end of the screen, and means comprising shelves on the insideozt` the sievev adapted to limit the sliding of the ore there?v on and toelevate theover-size material andcomprising to dump it into the over-size launder;

8. A metallur 'cal sizing screen c'bmprisf, ing a rotary tu nlar sieve, and entry ,and

longitudinally therein, organied @for substantially straightline travel of the material to screen, .in combination with devices distinct from the sieve mounted on the linside of the a screen to limit rolling and capable in themselves of elevating the over-size and deposit-- ing itin the over-size launder.

9. An ore-sizing screen, comprising, in rotary tubular sieve, bearings supporting said sieve at lengthwise spaced points 'on its outer portion, an entry launder entering at one end of 130 adapted to -95" comprising in? y an outlet toward the v` 'fris and beyond the .125v4 said sieve and eiiteiiding lengthwise thereof the oven-size material and dump it into the 10 near the loottomto` deposit the pulp thereon over-size launder.

`the full length Vof the sieve, an over-size In witness whereofl have signed lmy' name landet/,extending lengthwise of the' sieve in the presenee of two subscribing witnesses.

above said entry launder being inclined,` toward the opposite end ,of the sieve, and 'HERBERT A' MEG'RAW' shelves projecting from-.the inside of the Witnesses:

sieve and extendingrthe full length thereof J. F. BRANDENBURG, to limit the sliding of .the ore and to elevate LOUELLA F. LITrLE.

npies of thsipatent mj be obtained for ve cents each, by addressing the Commissioner of Patents,

l Washington, D. C.

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