US1040804A - Apparatus for classifying or grading crushed ore and the like. - Google Patents

Description

G. H. STANLEY. APPARATUS FOR OLASSIFYING 0R GRADING ORUSHED ORE AND THE LIKE.

APPLICATION FILED SEPT. 30, 1911.

Patented 0ct.8,1912.

Attorney. '1

-- UNITED STA PATENT E? ononon HARDY STANLEY, or cronannnsnuno, 'rnausvnan, Ass ren'on 'ro SANDS 1 LIMITED, or .ronnmvnsnune, 'rnansvaan.

uranarns ron CLASSIFYING' on onnmuo cnu'snnn can AND THE LIKE.

Specification of Letters Intent.

Patented (lot. 8, 1912.

' Application flied September 30, 1911. Serial-4W. 852,208.

To all whom it may concern: I'IARDY STAN- Be it known that I, Gnonos LEY, a British subject, rcsidin at the South African School of Mines and Technology, Johannesburg, Transvaal, have invented new and useful Improvements in Apparatus for Classifying or Grading Crushed Ore and the Like, of which the following is a speci fication.

Crushed ore and like ulverulent material has hitherto commonly eengraded both by hydraulic classification and by screening. Separation eflected solely' by hydraulic methods is always imperfect; largely owing to the practical difiiculty of obtaining a recisely uniform stream-of liquid in whic to etlect the settlement of the larger and (or) heavier particles. W'hile therefore itis at present possible to obtain from a hydraulic classifier an underfiow containing practically no material of less size than that desired, this can onlv be done upon so increasing the velocity of the current as to carry an undue roportion of the larger material away with the overflow. On the other hand screening possesses the advantage of enabling well defined products to be obtained,

' but has not hitheito been largely employed loo owing to the relatively low output and constant'tendency to choke. In ore screening operations hitherto known, the material has been fed onto the screen from above and has passed through the same by gravity, assisted frequently by water sprays, vibration or brushing of the screen, and the like. In

all such cases not only, on he one hand, is

the gravitational mov'ementof the finer material through the screen hindered and rendered sluggish by the clingin tendency of said material, but on the ot or hand the oversize is necessarily retained on the surface of the screen for a relatively long period, a. 6., while traveling from the oint at which it is fed to the oint of disc arge from the screen, during t e whole of which period it blinds a comparatively large p portion of the screen apertures.

The present invention consists in a combined hydraulic and screening a paratus, which affords the large output 0 the h draulic system with the precision obtainah e by the use of screens.

The invent-ion also consists in a hydraulic classifier provided with mechanical and posxtive means of high-capacity for separating from the overflow the oversize material which would otherwise be carried off with it and returning such material to the underinvention, the'granular material in admixture' with liquid is subjected to hydraulic classification by flowin it in. any 04') re priate manner to cause t 1e settlement 0 the eavier and (or) larger material. The rate of settlement in this ste is so adjusted that none of the lighter an terial which it is desired to carry oil with the oyerfiow will settle at this stage with the heavier and .(or) larger material; vor at least. so that the proportion of such According to the method of the present (or) smaller maligl tenand (or) smaller material which so A settles 18 substantially less than in the pres- 1 cnt methods. As a. consequence, a'relatively large proportion of heavier and (or) larger material will be carried on without settlement. The liquid carrying the remainin material is now passed through a screen 0 the proper mesh to arrest oversize material. The screen is so positioned in relation to the overflowing stream that solid particles of the pulp are or tend to be carried through it solely bythe flow of the liquid in eon-tradistinction to the present gravitational method, and so also that material rejected a recipgdicating screen fitted in the manner descri and through which the overflow is caused to pass.

In the accompanyin drawings Figure I is a verticalsect-ion 0% an upward current hydraulic classifier arranged according to this invention, and Fig. II is a vertical section of an ordinary cone classifier modified in accordance with the invention.

Referring to Fig. I, the casing a is divided into two compartments 1) and c by a partition 01. e is a launder issue; supply of pulp. The bottom of the casing is curved or sloped as :shown and the bottom oi the a partition is correspondingly shaped to form or a pipe for the larger or heavier material,

therewith a constricted passage f throughwhich pulp will pass rapidly and in a regularstream from compartment 6 to c0mpart-- ment 0. In orderto obtain the best results i compartment 0 should increase considerably in area toward the top. In the course of passage f there is formed a slot 9 or other opening leading to a collecting chamber h whence said material is discharged by means of a siphon or other known device. k is a pipe for supplying hydraulic water in the known manner. The screen Z forms part of one side of the compartment 0 and ma conveniently be set substantiall vertica 1y as shown. It is arranged to slic e vertically in a housing m and is reciprocated by sudh' means as the lifting tappet 'n. and the spring 0 tending to force it downward. The re-.

ciprocations shouldbe rapid, but need be of but small amplitude. The effect of tappetare carried again into contact with it they are at once detached again and thrown farther toward the bottom of the screen. "As

the shocks follow each other in rapid-$110" ccssion the screen isthus kept almost'constantly free from particles resting against its surface and its capacity is maintained at a very high value. For preventing pulp from entering between the screen frame and the housing, the joint'may be covered with a pliable strip of fabric or rubber p," or clear water may be injected intothe joint in the well known manner. 7 is a trough at about the level of the top of the screen and r an outlet forming therewith a spillway or bypass for passing surplus pulp from compartment 0 independently of the screen. In

the operation of this device the pulp in passing through passage f is subjected to hydraulic classification according to well known principles, whereby a greater or less amount of the heavier and (or) larger e. the less buoyant) particles tends to settle and pass oti through the slot 9. Thus when treating crushed ore comprising relatively light material such as quartz and heavier material such as pyrite, the particles of pyrite, although usually of relatively small volume, tend to settle with the larger quartz particles. The smaller and (or) lighter (2'. e. the more buoyant) particles, together with such of the larger particles as failed to setus. continue with the stream into compartment 0 of the classifier. The stream enters said compartment with considerable velocit which 'however'is rapidly diminish as thematerial moves up the compartmerit a owin iplartment an to the outflow of liquid. and er material through the screens Conseto the flaring of said comquently the less buoyant material still car-.

ried by the stream is to a large extent caused to settle without comin into contact with the screen at all. Fina ly the screen stops all the remaining large particles, while per mitt-ing the smaller particles to pass through 'it' with the stream. The large particles settled hydraulically in chamber a fall,

down principally at the back of said compartment near. to the partition d and at the 1 front near toQthe screen, at both of which'places the velocity of the current is reduced'owingI to skin friction. Those which settle'at the back of the compartment fall from the lowerend of the backwardly sloping part of} partition d through the stream passing u frompassage f and are thereby subjecte further washing. or classification. The whole of the oversize particles ..ultin!ately pass down passage 1 nearto the walls thereof where -the ve-.

locity of the current is reduced owing to its vfriction against the walls,--and thus they reach the slot g; In the event of the screen becoming choked by large floating "material such asbits-of wood, cinders-and the like, the pulp will pass oil -from compartment 0 by-way of trough q and'outlet'r carrying the floating particles with it and so causing the screen to be cleared. Such arrangement moreover obviates diificulty due to 'a casual; excess'of flow beyondthe. ca-

pacity cf the screen, ,without deranging the character of the products, since the'surplus pulp -will generally be properl owing to its diminished velocity ue to the widening of compartment 0 at the top and to the escape of most of the water through the screen. The surplus pul passed off graded.

through 1' may be returned to that-flowing I oil through the screen; The apparatus may if desired be so operated as to cause a con-' stantout-flow fromthe spillway.

The device described in so far as' it consists of the passage f, slot g, receiver h and water inlet lr-does not differ essentially from lmown upward current classifiers. An apparatus comprising these parts and afiording free overflow from the top of the rising part of passage f would classify material to the same extent as the average hydraulic classifier'in commercial use. It would .also exhibit the defect of the usual classifiers, thatis to say that if itwere so worked that substantially none of the material which it moderate quantity of material which it is desired so to settle would inevitably be passed off also with the overflow. In order to combine the vertical screen with such a classifier, the chamber 0 is provided to accommodate the pulp after it has issued from the classifier proper and while it is passing to the screen; said chamber being relatively tall as compared-with the classifier proper owing to the smaller flow possible per unit of screen area as compared with thefiow perunit of free overflow area. Said chamber however besides serving this purpose, also enables further hydraulic classification of the stream to be effected as already described, thus aiding in keeping the screen free. It is to be noted thatthe addition of chamber 0 .is not merely the equivalent of making the hydra ili c cla'ssifier deeper or in other words converting it into a spitzlutte, since if the lower part of the classifier were already designed for proper hydraulic separation, raising ,its outlet by means of chamber a would simply cause it to choke up. Such choking in the present case is obviated by the flow of pulp through the Ecreen from the bottom to the top of cham- Fig. II shows an ordinary cone classifier fitted with a cylindrical reciprocating screen Z for the overfiow.- The equivalent of the chamber 0 above the classifier proper as shown in Fig. I, is here constituted by the space inclosed by the screen. A trough q forming a spillway may conveniently be mounted on the inlet pipe e. Similarly a spitzkasten may have its discharge side fitted with a reciprocating screen.

It will be manifest that where a classifier is adapted to give more than two products, each of the products beyond the largest may be passed through a screen of appropriate ine'sh and arranged in accordance with this invention.

buoyant material and constructed for continuous separation of less buoyant material from more buoyant material, a reciprocating screen forming with parts of said classifier a compartment adapted to contain pulp, said screen providing the outlet for more buoyant material and being so positioned that oversize material may fall directly from it by gravity.

2. The combination of a hydraulic classifier having an undcrflow outlet for less buoyant material separately from the more buoyant material and constructed for continuous separation of less buoyant material from more buoyant material, and a substantially vertical reciprocating screen forming with parts of said classifier a compartment adapted to contaip pulp and providing the outlet for more buoyant material.

3. The combination of a hydraulic classifier having a restricted passage comprising a rising portion and an underflow outlet at the lower end of said rising portion, and a reciprocating screen positioned to receive pulp from said rising portion and to permit oversize rejected by it to fall directly by gravity to the lower side of said rising portion of the passage and thence to the outlet.

4. The combination of a hydraulic classifier hav'ing an underflow \outlet for less buoyant material separatelyfrom the more buoyant material and constructed for continuous separation of less buoyant material from more buoyant material, a chamber forming an extension thereof into which the more buoyant material passes, and a vertical reciprocating screen bounding said chamber.

5. A structure having an upwardly flaring compartment, a substantially vertical screen bounding said compartment, means for reciprocating the screen, said structure also having a restricted pulp inlet passage opening into the compartment obliquely at the base of the screen and a slot in the lower wall of said passage, and receiving means into which said slot opens.

In testimony whereof Ihave signed my name to this specification in'thepresence of two subscribing witnesses.

Witnesses: i

C. B. HENDERSON, B. PULLIN.

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