US2136686A - Classifier - Google Patents

Description

H. HARDINGE Nov. 15, 1938.

CLASSIFIER Filed Jan. 11, 1956 4 Sheets-Sheet 1 om mu E We N m R A H a w o L R A H H. HARDINGE Nov. 15, 1938.

CLASSIFIER Filed Jan. 11, 1936 4 Sheets-Sheet 2 3mm HARLOWE. HARD NGE H. HARDINGE Nov. 15, 1938.

CLASS IFIER Filed Jan. 11, 1956 4 Sheets-Sheet 3 gwuc/wtm? HAR LOWE HARDI NGE W k. W

H. HARDINGE Nov. 15, 1938.

CLASSIFIER Filed Jan. 11, 1956 4 Sheets-Sheet 4 HARLOWE. HARDINGE Patented Nov. is iass UNITED STATES CLASSIFIER Ha'rlowe Hardinge, York, Pa., assignor to Hard- Y inge Company, Incorporated, York, Pa a corporation voi! New Yorlr Application January 11, 1936, Serial No. 58,735

10 Claims.

This invention relates to apparatus of the type used for separating various kinds of materials, and more particularly to the type of apparatus usedin the metallurgical and other industries for 5, classifying purposes.

More specifically classifiers of the type falling within the scope of the present invention find use in almost every metallurgical operation where a mill grinds ores. The devices are also used for a 10 great many industrial purposes and may be used to wash sands, and other minerals. The devices may also be used in connection with grinding mills where they act in the capacity of classifiers which pass on as a product material of a given 15 fineness but which returns the oversize material for further grinding.

An object of the invention is to provide an improved classifier by which a close separation of materials may be obtained and in which the prod- 20 not is uniformly fine and the oversize is clean in that it contains a minimum amount of fines which should go out with the product.

Another object of the invention is to provide an improved classifier in which the oversize material 5 is discharged from the main classifying chamber with a minimum amount of wash water.

Another object of the invention is to provide an improved classifier in which the oversize material moving through the main classifying chamber 3 is dewatered to a greater extent than was possible in prior devices of a similar nature, and in which the water removed from the oversizematerial adjacent the discharge end of the main classifying chamber can readily flow backwardly through 35 said chamber without carrying with it a preponderance of oversize material.

Another object of the invention is to provide an improved rotary wet classifier in which the oversize material is'propelled through a main classify- 40 ing chamber against a countercurrent of wash --water by means of a screw fiight of varying pitch and height which squeezes the oversize material as it approaches the discharge end of the classifler, and in which slots are formed in the portion 45 of the screw flight adjacent the discharge end of the classifier through which surplus-wash water squeezed from the oversize material can readily flow back into the middle portion of the classifying chamber without carrying a preponderance 50 of oversize material with it.

' Another object of theinvention is to provide an improved classifier of the character mentioned, which is simple in construction, and reliable and exact in function under all conditions of service. 55 The invention also comprises certain new and useful improvements in the construction, arrangement and combination of the several parts of which it is composed, as will behereinafter more fully described and claimed.

In the accompanying drawings:-

Figure 1 is a vertiial longitudinal section of a classifier embodying the invention;

Fig. 2 is a transverse section taken on the line 2--2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is an elevation of the oversize material discharge end of the classifier, showing the slots in the portion of the screw flight adjacent this end of the device;

Fig. 4 is a view similar to Fig. 3, showing the slots equipped with members for varying the area thereof;

Fig. 5 is an enlarged view. partly in section, of a portion of the structure shown in Fig. 4;

Fig. 6 is a horizontal section taken on the line Fig. 7 is a section of the oversize material discharge end of a classifier having elevating and dewatering buckets; and

Fig. 8 is a section taken on the line B8 of Fig. 7.

Referring to the drawings, the classifier comprises a main body portion or drum' II which is preferably mounted for rotation with the axis of the drum inclined with respect to the horizontal, as shown in Fig. 1, said drum being supported on a suitable base or frame i2.

For the purpose of rotating the drum ii, any suitable mechanism may be utilized. In the present instance the driving mechanism is shown as including an electric motor [3 which is operatively connected through gears it, to a chain driving means l5 of any approved construction.

For convenience the left hand end of the drum ii, as illustrated in Fig. 1, will be referred to as the front end and the right hand end of the drum I i will be referred to as the rear end.

The right hand or rear end of the drum ii is the end through which material to be classified is fed into the drum, and the left hand or front end is the end through which the oversize material is discharged- As shown in the present embodiment of the invention the axis of the drum ii is inclined upwardly from right to left.

The material is adapted to be delivered into the classifier by means of a chute or trough [6 which terminates at a suitable distance from the right hand or rear end of the drum I l.

The right hand or rear end wall ll of the drum mounted an annular band It.

The W of the band It is to provide an inlet opening for the classifier, and said band is so formed as to provide a lip over which the fines and water or other liquid, either as a wash or that enters with the feed, are discharged from the classifier. The fines and water or other liquid'discharged from the classifier fall into a trough 2| and are thereby carried away from the device.

For the purpose of conveying material from the right handor feed end of the drum towards the left hand or front end thereof and also for turning the material over in the water within the drum means in the form of a helical trough or screw flight 2| are provided.

The helical trough or screw flight 2| .comprises a metal band arranged around the inner wall of the drum II in thei'orm ofascrew whichiscoextensive with said drum.

The height of the metal band 2| varies from end to end, said band being of considerably less height at the right hand or feed end of the drum I, than at the left hand or discharge end of said drum, so that the helical trough or screw flight will gradually increase in depth from the rear end toward the front end of the drum II.

In order to provide for a squeezing action of the material passing through the drum II, the pitch of the band 2| is varied from one end of the drum to the other. That is to say, the convolutions of the band 2| are so formed that the helical trough is considerably narrower at the left hand or front end than at the right hand or rear end ofthedrum The construction and arrangement of the band 2| is such that a series of pockets or compartments are formed for containing the material, the compartment at the right hand or rear end of the drum being comparatively broad in width and shallow in depth, as indicated at 22, Fig. 1, and the compartment 23 at the left hand or front end of thedrum being comparatively narrow in width and high in depth, and also being less in cross sectional area than the compartment 22. The intermediate compartments 24, 25, 28 and 21 progressively change in cross sectional dimensions. I

The manner in which the helical band is constructed is clearly shown in Fig. 2, and as there shown said band may be formed of a series of plates cut from sheet metal of suitable gauge and fastened together and secured to the wall'of the drum II by any desired means, such as welding, riveting, or the like.

Preferably the edge of the helical trough 2| abutting the wall of the drum should be made integral with the wall of the drum, so as to prevent the passage of water and fines along the inner surface of the drum.

The portion of the helical trough nearest the oversize discharge end of the drum I I, is formed an opening" having a discharge lip 8| for the oversize material.

The material discharged from, the front end of the classifier falls into a trough I2 and is thereby carried away from the apparatus.

Projecting through the opening til, is a pipe 23, through which wash water is supplied to the classifier.

In operation, assuming that the classifier is charged with material and water and the drum I is being rotated through the operation of the motor it, each of the compartments 22, 24, 25, 28,

21 and 23, between the screw flight or helical trough 2|, will contain varying quantities of material.

The water line of the classifier is normally above the rear discharge opening provided by the lip It, as indicated by the broken line, Fig, 1, and since it is customary to have the classifier in a slightly tilted position with the rear end lower than the front end, the direction of flow of water will be towards the rear end even though no extra wash water is introduced into the classifier through the pipe 23.

The rear end'portion of the classifier as defln by the compartments 22 and 24 and the zone above them, functions as a primary settling chamber. During the operation of the device the coarse or oversize material will settle in the bottom of the drum II, and the finer and other material which may have a tendency to float or is carried in suspension in the water will be carried out of the classifier by the water which passes over the lip It.

The oversize material which settles in the bottom of the drum II is forced, through the action of the helical trough or screw flight 2|, towards the left hand or discharge end of the drum, the material being constantly turned over by the ratation of the drum and the action of the helical trough.

In its forward movement through the drum I, the oversize material comes in contact with cleaner and cleaner wash water, and as the material turns'over, the finer particles which are disposed between the coarser particles are liberated, and the wash water carries these particles of fines with it towards the overflow or rear end of the classifier. In this way the water passing from the front end of the classifier towards the rear end washes the coarse particles clean of fines, dirt, slimes, etc.

Due to the construction and arrangement of the parts comprising the helical trough or screw flight 2|, the depth of material contained in the successive compartments between the convolutions of the helical trough varies from right to left, as has heretofore been described, so that, as the material moves toward the discharge end of the classifier, a squeezing action is gradually imparted to the material and the oversize is condensed or compacted. This condensing of the oversize material is effected by the elimination of the finer material by the washing action and overflow over the top of the helical trough as the cross section of said trough becomes smaller towards the discharge end 3| of the apparatus.

The purpose in so constructing the helical trough 2| is to build up the successive masses of material, so that when the material enters the last zone, as defined by compartment 2!, the ratio of water to solids therein is considerably less than that in the rear or feed end of the classifier.

.Another advantage resulting from constructing the helical trough 2| in such a manner is that the water, in flowing from left. to right through the drum H, is caused to pass from one compartment to the next in a series of cascades, and in so doing the water carries with it the finer material which becomes exposed as the oversize material is turned over as it is worked toward the discharge end.

As shown in Fig. 1, the height of the helical trough between compartments 23 and 21 is above the level of the water in the classifier, so that wash water flowing from compartment 23 is caused to fall in the'form of a cascade into compartment 21. Furthermore, the height of the portion of the helical trough between compartments 21 and 26 is considerably higher than the height of the portion of the helical tr ugh which gradually lower towards the rear end .of the classifier, when the level of the water in the drum II is lowered, additional cascades will be formed.

Also, should the oversize discharge or left hand end of the classifier be elevated to a position higher than that illustrated in the drawings, this cascading effect can be produced without decreasing the amount of wash water admitted to the classifier, since the rear or right hand end of the drum U will be so much lower than the left hand or oversize discharge end of the drum, that the level of the water in the drum willnot extend as fartcward the left as illustrated in Fig. 1, with the result that additional portions of' the helical trough 2| will project above the water.

Since the screw flight or helical trough 2| terminates at the left hand end of the drum H, the material will be discharged from the compartment 23 over the discharge lip 3| and from thence fall into trough 32.

When the classifier is operated at normal capacityeach of the compartments between the helical trough 2| will be filled with material and wash water, and since the material is squeezed or compacted in the several compartments by the action of the helical trough, it is of advantage to dewater the material as it approaches the oversize discharge end of the classifier, so that a minimum amount of water will pass out of the classifler with the oversize material.

Therefore, according to the present invention, the left hand portion of the helical band 2| is formed with the series of notches 28, heretofore referred to.

The purpose of these notches or slots 28 is to permit surplus water in the compacted material in the high portion of the classifier to drain back into the more saturated and loosely compacted material in the lower part of the classifier,

It will be noted by referring to Fig. 1, that the last flight to the left of compartment 23, is much higher than the discharge lip 3|, so that the oversize will be forced out a large part of the revolution of the drum ll, rather than at only one point. The water in the material being discharged drains back into the drum through the slotted openings 28, and if so desired the area of these openings can be varied or adjusted to suit varying conditions and various kinds of material.

As'shown in Figs. 4, 5 and 6, one manner of adjusting the sizes of the slots 28 is to employ an adjustably mounted plate 34 for each slot.

The plates 34 are preferably formed of 2. rectangular piece of sheet metal or plate steel.-

Attaching elements which may be in the form of bolts 33 are mounted in openings 38 formed in the helical band 2| adjacent one edge of the notches 28.

The plates 34 are formed with a series of open- 5 or slots 28 and thereby reduce the size of said slots, and in order to prevent an onrush of material through the slots 28 with the water flowing therethrough, the edges of the plates 34 paralleling the adjacent side edges of the slots, are bent outwardly, as indicated at 38.

In the drawings, the plates 34 are shown as only partly covering or overlying the slots 28. However, should it be desirable to nearly close the openings through the slots, the plates can be shifted further to the right, as viewed in Fig. 5,

in which position the outwardly bent portion 38 will overlap the portion of the helical band 2| to the right of the slots 28. Also, it will be understood that the openings 31 may be so disposed in the plates 34 that said plates can be so located with respect to the slots 28 as to vary the depth of the opening of said slots, as well as the width g th5e slots, as is illustrated by dotted lines, in

When the oversize material is comparatively 30 coarse, obviously the plates 34 can be positioned with respect to the slots 28 so as to permit a considerable amount of water to flow through the slots without carrying with it an undesirable quantity of material. On the other hand, the 35 material will be prevented from flowing back with the water in objectionable quantities.

Instead of discharging the oversize directlys from the compartment 23 to the discharge lip 3|, the classifier can be formed with an enlarged discharge head 40, as shown in Figs. 7 and 8.

This discharge head contains a plurality of buckets 4| which function as elevators that scoop up the material and deposit the same into a discharge trough 42. The trough 42 extends downwardly through an opening 43 in the outer 5 end wall of the head 40 and terminates over a chute 44.

The left hand or front end of the drum opens directly into the head 40. The helical trough 2| terminates adjacent to the junction of the drum II with the head, so that the material, in moving forwardly through the drum is forced by the last flight 45 into the bottom of the head 40.

The buckets 4| may be so constructed that the material deposited in the bottom of the head 40 is readily picked up and carried upwardly to a point above the level of the water in the classifier whereby the water quickly drains from the elevated material before such material is discharged from the buckets.

As shown in Fig. 7 the feed water pipe 33 may terminate in the discharge head 48. However, it should be noted that when so desired, said pipe can extend through the head 40 and terminate in the main classifying chamber of the drum The point at which the feed water pipe 33 terminates depends entirely upon the kind of material being classified. Thus, should the ma'-'- terial delivered to the discharge head 40 from the.

main classitying chamber contain an undesirable quantity oi slimes, dirt, etc., it will be advantageous to deliver the wash water into the discharge head 40, so that the oversize material will be further cleansed. On the other hand. should the .oversize' material being discharged trom the drum H into the head 40 be comparatively clean, and require no further washing,

shown in Fig. 1.

then the water pipe 33 can extend through the head 40 and terminate over compartment 23, as

In this case the oversize material in the head 40 will be substantially dewatered, since very little wash water will fiow therewith past the end 45, on account of the drains provided by the slots 28 and the dam eflect oi. the successive compartments.

Having thus described my invention, what I claim is:-

1. A classifier comprising a rotatable classifying chamber having end walls, a fines discharge opening in one end wall of said chamber, an oversize material discharge opening in the opposite end wall of said chamber, and a helical band disposed around the interior of said chamber for moving material towards said oversize discharge opening, said band decreasing in pitch and increasing in depth from the fines discharge end toward the oversize discharge and of said chamber, the decrease in pitch of said band being at a greater rate than the increase in depth with respect to the volume, whereby the net volume of material carried by the band constantly decreases and is zero where the band terminates at the oversize discharge end wall of the chamber.

2. A device of the class described comprising a rotatable drum having an impervious wall, a helical trough fixed to the interior of the drum and adapted to prevent the passage oi. water and other matter along the inner surface 01' the drum, the height oi said trough gradually increasing from one end of the drum towards the other, means for supplying wash water to the drum, and notches formed in the highest portion of said trough, said notches extending downwardly of the trough varying distances, the notches in the portion of the trough of greatest height being deeper with respect to the height of the trough than the depth of the notches formed in said trough rearwardly of the end of the drum, whereby liquid in the material in the highest portion of the trough can drain backwardly towards the opposite end of the drum.

3. A device of the class described comprising a rotatable drum having an impervious wall, means for supporting the drum in a position tilted from the horizontal, means for rotating said drum, a screw flight fixed to the interior of the drum and adapted to prevent the passage oi. liquid along the inner surface of the drum, the pitch of said screw flight at the lower portion of the drum being relatively steep for rapidly advancing material toward the upper end of the drum when the drum is rotated, and notches in one end portion or the screw flight for draining liquid in the portion of the drum at the upper end thereof back towards the lower portion of the drum, said notches extending downwardly into the screw flight varying distances, the notches formed in the portion of the screw flight of greatest height being deeper with respect to the height of the screw flight than the depth of the notches formed in said screw flight rearwardly of the upper end of the drum.

end through which fines and liquid are discharged, an opening at the front end of the drum through which oversize material is discharged, a helical band extending through the drum and adapted to prevent the passage of liquid along the inner surface of the drum, said helical band being adapted to convey material delivered into the rear end of the drum toward the front end thereof, means for supplying liquid to the drum. said helical band gradually increasing in depth from the rear end towards the front end of the drum, the portion or said band adjacent the rear end or the drum being submerged by liquid in the drum, the portion of the trough adjacent the front end of the drum extending above the liquid in the drum, said drum having an impervious wall, and means for draining liquid from material in the portion of the helical band adjacent the front discharge end 01' the drum back towards the rear discharge end of the drum comprising notches formed in the portion of said band adjacent the discharge end of the drum, said notches extending downwardly into the band varying distances, the notches formed in the portion 01' the bond of greatest height being deeper with respect to the height of the hand than the notches formed in said band rearwardly or the discharge end of the drum.

5. A classifier comprising a rotatable drum having a fines and liquid discharge opening at one end and an oversize discharge opening at the opposite end, a helical band for moving material through the drum from the fines discharge end towards the oversize discharge end of the drum, means for supplying liquid to the drum, and openings formed in the helical band adjacent the oversize discharge end of the drum for draining liquid from compartments between said band back towards said fines discharge end, said openings extending downwardly into the helical band varying distances and terminating above the wall of the drum, the openings formed in the portion of the helical band adjacent the oversize discharge end of the drum being deeper with respect to the height of said band than the openings formed in said band rearwardly of the oversize discharge end.

6. A classifier comprising a rotatable classifying chamber having end walls, a fines and liquid discharge opening in one end wall of said chamber, an oversize discharge opening in the opposite end wall oi said chamber, said chamber hava ing an impervious outer wall, a helical band disposed around the interior of said chamber for moving material towards said oversize discharge opening, said band being adapted to prevent the passage 01' liquid along the inner surface of said chamber, said band decreasing in pitch and increasing in depth from the fines discharge end towards the oversize discharge end of said chamber, the decrease in pitch oi said band being at a greater rate than the increase in depth with respect to the volume, whereby the net volume of material carried by the band constantly decreases and is zero where the band terminates at said oversize discharge and wall of the chamber, and notches formed in said band adjacent the discharge end of said chamber for draining liquid from the material, said notches extending downwardly into the helical band varying distances, the notches formed in the portion of the helical band of greatest height being deeper with respect to the height of the band than the notches formed in said band rearwardly oi. the oversize discharge end of said chamber.

'I. A classifier comprising a rotatable classilying chamber having end walls, a helical band mounted in said chamber and adapted to prevent the passage of liquid along the inner surface of the chamber, said chamber having impervious walls, one of said end walls having a fines discharge opening formed therein, an opening formed in the opposite end wall through which the oversize material is discharged, an enlarged head attached to the oversize discharge end or said chamber, means in said head for elevating the material delivered thereto from said chamber and for discharging the same from the classifier, the oversize discharge opening being greater in diameter than the internal diameter of said band at the point where said band terminates adj acent to said oversize discharge end of saidchamher, the convolutions of said band varying from the fines discharge end towards the oversize discharge end, whereby the net volume of material carried by the band constantly decreases, means for feeding material and liquid into said cham her, and notches formed in the portion of said band of lesser volume for draining liquid from the material back towards said fines discharge end of the classifier, said notches extending downwardly into the band varying distances, the notches in the end portion or the band being deeper with respect to the height of said band and all of said notches terminating above the wall of said chamber.

8. A classifier comprising a rotatable drum mounted on an inclined axis and having annular end walls providing central openings for the drum, the opening in the lower end wall serving as a fine material discharge opening and the opening in the upper end wall serving as an oversize material discharge opening, and a hellcal band disposed around the interior of the drum for moving material towards the oversize discharge opening, said band extending the entire length of the drum and terminating in contact with the upper end wall of the drum, said band decreasing in pitch and increasing in depth from the fines discharge end toward the oversize discharge end of said drum, said oversize discharge opening being greater in diameter than the opening through the band at the discharge end oi the drum 9. A classifier comprising a rotatable drum mounted on an'inclined axis and having annular end walls providing central openings for the drum, the opening in the lower end wall serving as a fine material discharge opening and the opening in the upper end wall serving as an oversize material discharge opening, a helical band disposed around the interior of said drum for moving material towards said oversize discharge opening, said band extending the entire lengthvof the drum and terminating in contact with the upper end wall of the drum, the band increasing in depth from the fines discharge end toward the oversize discharge end of the drum, said oversize discharge opening of the drum having a diameter greater than the diameter of the opening through the band at the oversize discharge end of the drum, meanstor supplying liquid to the drum, and openings formed in the sections of the band adjacent the discharge opening for draining liquid from material backwardly towards the opposite end of the drum.

10. A device of the class described comprising a rotatable drum mounted on an inclined axis and having annular end walls providing central openings for the drum, the opening in the lower end wall serving as a fine material discharge opening and the opening in the upper end wall serving as an oversize material discharge opening, a helical band fixed to the interior of the drum and adapted to prevent the passage of water and other matter along the inner surface of' the drum, said band extending the entire length of the drum and terminating in contact with the discharge end wall of the drum, the height of said band gradually increasing from the fines discharge end towards the oversize discharge end of the drum, means for supplying wash water to the drum, and notches formed in the oversize discharge end portion of said band, said notches extending downwardly into the band and terminating above the inner surface 01' the drum for draining liquid from the material in the portion of the band adjacent the oversize discharge end oi the drum backwardly towards the opposite end of the drum.

HARLOWE HARDINGE.

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