US2226750A - Classifier - Google Patents

Description

Patented Dec. 31, 1940 UNITED STATES PATENT OFFICE CLASSIFIER Application December 17, 1938, Serial No. 246,328

12 Claims.

My invention relates to classifiers employing rakes or drags to move solids toward an exit end of the machine and has particular reference to a device for avoiding and minimizing agitation and surging of the liquid by movement of the drags or rakes.

In mining and allied industries, classifiers are employed for many different purposes, such as the classifying or separating of large and small particles of solids from each other as yby mixing the solids with suitable liquid which -is then passed to the tank or vessel of the classifier, the larger particles settling to the floor or deck of the tank from which they may be carried out of the machine, while the finer particles remain in suspension in the liquid and are drawn out of the liquid exit from the machine. These machines are also used for the washing of ores, coal or other materials in which a pulp or liquid mixture of the material to be washed is fed into the tank or vessel and the larger particles are conveyed out of the machine by means of drags or rakes, while the water and such finer particles, dirt or debris as will remain suspended in the liquid will pass out of the liquid exit of the machine.

Present types of classifiers employing drags or rakes for moving the solids toward the exit end of a machine are arranged to move the drags forwardly toward the exit end of the machine while in a lowered position adjacent the bottom of the deck upon which the solid materials rest and rearwardly toward the opposite end of the machine while raised above the floor of the deck. This motion may be accomplished in various types of classifiers by moving the drags through a rectilinear path or a circular path or a combination of these two paths by employing a translatory movement during the forward and rearward movement of the drags and a rotary movement at either end of the travel to raise and lower the drags.

One of the diiiiculties encountered with present constructions, particularly in regard to those classifiers in which the drags are lifted .completely out of the liquid during the return stroke, lies in the fact that upon each re-entrance of a particular drag into the liquid, the drag presents a relatively large surface area transverse to its movement in entering the liquid so that a more or less violent surge of the liquid occurs. Such surging of the liquid produces undesired agitation in the liquid and presents the efficient separation of the larger solids therefrom and causes a considerable portion of the larger materials to pass out through the overflow, through which only the finer particles are intended to pass.

It is therefore an object of my invention to provide a classifier of the drag type in which the drags are completely removed from the liquid during the return portion of their movement and re-inserted in the liquid at the completion of the return movement in such position as to present a minimum vsurface area to the liquid to avoid surging thereof.

It is an additional object of my invention to provide a rotary classifier of the character set forth in which drags are pivotally mounted upon the circumference of a wheel in such fashion that the drags present a maximum surface area to the liquid during the forward and leaving portions of the movement of said drags and present a minimum surface area to the liquid upon the reentering portion of their movement.

It is also an object of my invention to provide in a drag classifier of the type in which the drags are completely removed from the liquid during the return portion of their movement, a pivotal mounting for supporting the drags from the mechanism for moving the drags such that the drags present a maximum surface area to the liquid during the forward portion of their movement and present a minimum surface to the liquid upon the re-entering movement.

It is also an object of my invention to provide a two-stage rotary classifier of the character set forth hereinbefore wherein one stage operates to lift the larger solids a portion of the desired distance and a subsequent stage or stages operates to lift said particles the remaining distance and re-classify the larger particles transferred thereto-from a preceding stage.

Other objects and advantages of my invention will be apparent from a study of the following speciiications, read in connection with the accompanying drawings, wherein:

Fig. 1 is an lelevation of one form of rotary classifier of my invention;

Fig. 2 is a longitudinal vertical section similar to Fig. 1 showing the mounting mechanism for the drag blades, together with the cams which are employed to cause the proper sequential operation of each of the blades relative to the other;

Fig. 3 is a schematic view illustrating the manner in which two or more mechanisms, similar to the type illustrated in Fig. 1, may be employed to form a multi-stage, rotary classifier; and

Figs. 4, 5, 6 and 7 are fragmentarysectional views illustrating, by their sequential arrangement, the successive stages of operation of adrag blade and cam mechanism during the time said blade is operated to discharge from the machine the larger particles carried by said blade.

Referring to the drawings, I have illustrated in Fig. 1 one form of the rotary classifier of my invention as including a supporting structure comprising a pair of side frames I which are held in spaced relationship relative to each other, each of said side frames including Vertical members 2, a base member 3 intertying the lower ends of each of the vertical members 2 and an upper horizontal member 4 interconnecting the upper ends of the vertical members 2. The side frames may be held in the proper spaced relationship relative to each other by means vof transversely extending spacing and bracingmembers (not shown).

The supporting structure is preferably lined with sheet metal, or other suitable medium to provide a tank 5 including an overflow or liquid discharge 6 disposed below the upper horizontal member 4 and a discharge lip 'I for the larger particles which is disposed at the approximate level of or slightly above the upper horizontal member 4. The material to be classiiied may be introduced as a pulp or liquid suspended mixture through any suitable inlet such as is indicated at la. The tank 5, which is formed by the sheet material secured to the side frames I, is .preferably made of a semi-cylindricaLshape, the axis of said cylinder being disposed substantially at right angles to the plane of each of the side frames I and above the upper horizontal member 4.

Each of the upper horizontal members 4 support a pillow block or bearnig bracket 8 for rotatably supporting a horizontal shaft 9 disposed on the axis of the semi-cylindricaltank 5. The shaft 9 is employed to rotatably support the wheel portion of `my rotary classier which may cornprise spaced wheels, each of which includes a hub member IU non-rotatably secured to the shaft 9 and carrying a plurality of radially extending spokes II to the outer ends of which is secured an annular plate I2. A plurality of drag blades I3 extend between each of the spaced annular plates I2 and each of the blades I3 are pivotally secured thereto as by pivot shafts I4 carried in supporting brackets I5 which may be suitably secured to each of the plates I2 and include a slotted opening I6 for receiving the end of the pivot shaft I4.

In operation, the classifier wheel is rotated by any suitable external means in the direction indicated by arrow I'I in Fig. 1 so that the drag blades I3 enter a pulp mixture in the tank 5 at the overflow point 6 and are caused to pass around the bottom of the tank 5 and discharge the larger particles picked up by the blades during this rotary motion through the discharge end I.

The manner in which this discharge takes place may be readily observed by reference to Figs. 4 through 7, Fig. 4 representing the solid-engaging position of the blade I3 at the initiation of the discharge operation. It will be noted in Fig. 4 that the drag blade I3 is maintained in a substantially radial position through engagement of the pivot shaft I4 with the slot I6 and a stop I8 carried by the blade I3 in a position to engage a supporting member I9 formed integrally with the supporting brackets I5. As theclassier wheel rotates the blade I3 is moved upwardly as viewed in Fig. 4 causing the pivot shaft I4 to engage a cam member 20 which isv carried by the sides of the tank 5, or suitable brackets secured to the side frames I. The cam member 20 is provided with a curved camming face 2| which forces the pivot shaft I4 outwardly away from the center of the classifier wheel as the wheel rotates, bringing the blade I3 into a position, as illustrated in Fig. 5, extending above and beyond the discharge lip 1.

In order that the blade I3, may during this movement, be caused to slope downwardly to begin the discharge of material carried thereby, the supporting member I9 is provided with a sloping supporting face 22 so positioned that as the stop I8 is slid outwardly thereover by action of the cam 20, the blade I3 will be caused to rotate slightly in a clockwise direction.

The supporting surface 22 of the supporting member I-9 is terminated at its outward end by means of a face portion 23 such that when the blade I3 is moved further outwardly by the cam 2li-from the position illustrated in Fig. 5 to that illustrated in Fig. 6, the stop I3 will fall off of the end of the supporting face 22 and allow the blade I3 to fall'by gravityv and sharply strike the discharge lip 'i so as to dislodge all of the material which is carried by the blade I3. As the wheel I2 progresses still further in its'rotary motion, the blade I3 is caused to assume a position as is illustrated in Fig. 7 in which the stop I8 is supported by a lower supporting surface 24 formed by a projection on the supporting member I9, the pivot shaft I4 being forced by the cam 20 to the extreme outward end of the slot IE.

Reference to Fig. 2 vwill show that as the classiier wheel continues in its rotation, the blade is carried in this position until it has been rotated sufliciently for the center of gravity of the blade and mechanism carried by the pivot shaft I4 to be disposed to the left of the pivot shaft, as viewed in Fig. 2, at which time the blade will rotate through substantially 180 under the induence of gravity and assume a downwardly depending position prior toits entrance to the liquid carried'by the tank 5.

In order that the blade I3 during the balance of the'movement may be brought into the proper solid-engaging position as has been illustrated in Fig. 4, I provide a cam member 25 which may be supported by the side frames I. The cam member 25 is preferably of such shape and so positioned as to engage the pivot shaft I4 as the blade I3 enters the fluid and force the pivot shaft I4 to the extreme inward endV of the slot I6 where it may fall by gravity into a depressed portion 26 of said slot. As thef wheel continues to rotate, the blade is pivotally'supported by this depressed portion 26 engaging the pivot shaft I4, the blade being disposed in a substantially vertical position. AnyV tendency of the blade to move in a counterclockwise direction beyond a radial position is, of course, arrested by the supporting member I9 so that the blade I3 is again brought into a solidengaging position, as illustrated in Fig. 4.

It will be seen that by employing thistype of support for each of the 'drag blades I3, the blades are caused to assume a rigid, radial position during their passage through the fluid so that larger particles of the pulp which have settled to the bottom of the tank will be engaged by the blades and carried upwardlyy toward the discharge lip I at which point the interaction of the cam 20 and the pivot shaft I4 causes those'particles to be discharged from the tank 5. As the rotation of the wheel iscontinued, each of the blades is caused to enter lthepulp in a substantially edgewise manner so as to 'cause a minimum of disturbance to the liquid and thus prevent surging and lconsequent discharge-of larger particles over lthe overliovf t.

It has Vbeen found for some types of classifying that a re-classification of the larger particles is desirable, and also that a classifier may be employed to lift the heavier vparticles to a higher elevation during the classifying operation.

Whenever a lift in excess of that provided by a rotary classifier of the type illustrated in Figs. l and 2 is required, or Whenever it is desired to reclassify the larger particles, a multi-stage arrangement such as that illustrated in Fig. 3 may be employed. In this arrangement the tanks 5 of each of two classifiers are made contiguous, with the overflow portion 6 of one forming the discharge portion l' of the classifier preceding. The second classifier is accordingly disposed vertically the corresponding distance above the preceding classifier so that material which is discharged from the iirst classifier is deposited in the tank of the second, the second classifier then operating to re-classify these particles and raise them to a still higher elevation before discharging them from the tank.

Inasmuch as some of the liquid and some of the finer materials of the pulp will be carried over with the larger particles, I provide a pipe or launder 5i) interconnecting the tanks of the upper and lower portions of themulti-stage classifier and connected at such levels in the tanks as to convey back to the first stage the finer particles and excess liquid which are carried over to the second stage from the rst.

It will be seen that this type of multi-stage classifier will be extremely useful when employed for such operations as coal washing or the Washing of rock or gravel when it is desired that the larger particles be completely free from smaller particles, such as dust, dirt and vegetable matter.

It will be noted that by providing the limited movement type of pivotal support for the drag blades on the classiiiers of my invention that I have provided a means whereby the blades are caused to positively engage heavier particles lying at the bottom of the classier tank so as to cause the discharge of these particles from the tank while permitting sufcient pivotal-movement of these blades to enable them to re-enter the pulp at the beginning of a discharge stroke in a substantially edgewise manner, and in this fashion have reduced the surging of the pulp to a minimum. As has been pointed out hereinbefore, the reduction of this surging to a minimum is essential in order to obtain the proper and satisfactory operation of a classier so as to accurately classify the constituents of the pulp into the desired classes.

While I have shown and described the preferred embodiment of my invention, I do not desire to be limited to any of the details of construction shown or described herein, except as defined in the appended claims.

I claim:

1. In a classier, the combination of: a semicylindrical tank for receiving pulp containing solids to be separated and having a bottom upon which solids may settle from the liquid. a wheel supported for concentric rotation Within said tank; a plurality of drag blades carried by said wheel in a position extending substantially radially away from said wheel and toward the bottom of said tank and held in spaced relation relative thereto for engaging such settled solids and moving them toward one end of said tank; means mounting each of said blades lfor radial outward movement relative to said wheel; and blade moving means cooperating with said blades and operable responsive to the arrival of each of said blades at said end of said tank to move said blade radially outward over said-end to discharge solids carried by said blade. v

2. In a classifier, the combination of: a semicylindrical tank'for receiving pulp containing solids to be separated and having a bottom upon which solids vmaysettle from the liquid; a Wheel supported for concentric rotation within said tank; a plurality of'drag blades carried by said wheel in a position extending substantially radially away from said wheel and toward the Ibottom of said tank and held in spaced relation relative thereto for engaging such settled solids and moving them toward one end of said tank; means mounting each of said blades for movement relative to said wheel; blade moving means cooperating with said blades and operable responsive to the arrival of each of said blades at said end of said tank to move said blade radiallyv outward over said end to discharge solids carried by said blade; and a mechanism responsive to further rotary movement of said wheel for releasing said blade to allow said blade to fall by gravity into violent contact with said end to dislodge solids adhering to said blade.

3. In a classifier, the combination of: a tank for receiving pulp containing soli-ds to be separated and having a bottom upon which solids may settle from the liquid; a drag construction for moving such settled solids toward one end of said tank including a movable drag carrier and a plurality of blades carried thereby in a position extending transversely of said bottom; drive means for moving said carrier in a direction to cause movement of said blades toward said end; means mounting said blades on said carri-er for outward movement relative thereto from a retracted position to an extended position; and blade moving means cooperating with said blade and operable responsive to arrival of each of sai-d blades at a predetermined point beyond said end -to move said blade relative to said carrier yfrom said retracted to said extended position and over the end of said tank to move the solids carried by each of said blades beyond the confines of said tank.

4. In a classifier, the combination of: a tank for receiving pulp containing soli-ds to be separated and having a bottom upon which solids may settle from the liquid; a drag construction for moving such settled solids toward one end of said tank including a movable drag carrier and a plurality of blades carried thereby in a position extending transversely of said bottom; drive means for moving said carrier inv a direction to `cause movement of said blades toward said end; means mounting said blades on said carrier for outward movement relative thereto from a retracted position to an extended position; blade moving means cooperating with said blades and operable responsive to arrival of each of said blades at a predetermined point beyond said end to move said blade relative to said carrier from said retracted to said extended position and over the end of said tank to move the solids carried by each of said blades beyond the connes of sai-d tank; and means engageable by said blade in said extended position for jarring said blade to rel-ease solids adhering thereto.

5. In a classifier, the combination of: a tank for receiving pulp containing solids to be sepf arated and having a curved bottom upon which solids may settle from the liquid; a Wheel supported for rotation within said tank; a plurality of drag blades carried by said wheel in a position extending substantially radially away from said wheel and toward the curved bottom of said tank for engaging such settled solids and moving them toward one end of said tank; means mounting said blades on said wheel for outward movement relative thereto from a retracted position to an extended position; and blade moving means cooperating with said blades and operable responsive to the arrival of each of said blades at a predetermined point beyond said end to move said blade relative to said wheel from said retracted to said extended position and over said end to discharge solids carried by said blade.

6. In a classier, the combination of: a tank for receiving pulp containing solids to be separated and having a curved bottom upon which solids may settle from the liquid; a wheel supported for rotation within said tank; a plurality of drag blades carried by said wheel in a position extending substantially radially away from said wheel and toward the curved bottom of said tank for engaging such settled solids and moving them toward one end of said tank; means mounting said blades on said wheel for outward movement relative thereto from a retracted to an extended position; blade moving means cooperating with said blades and operable responsive to the arrival of each of said blades at a predetermined point beyond said end to move said blade relative to said wheel from said retracted to said extended position and over said end to discharge solids carried by said blade; and means engageable by said blade in said extended position for jarring said blade to release solids adhering thereto.

7. In a classifier, the combination of a tank for receiving pulp containing solids to be separated and having a bottom upon which solids may settle from the liquid including an upwardly sloping portion terminating in an end over which said solids may be discharged; a drag construction for moving such settled solids toward said end including a drag carrier movable through a path conforming with said upwardly sloping bottom and a plurality of blades carried thereby in a position extending transversely of said bottom; drive means for moving said carrier in a direction to cause movement of sai-d blades in a forward direction toward said end; means mounting said blades on said carrier for movement relative thereto between a retracted position in which the blade is maintained substantially normal to said bottom as it is moved thereover and an Vextended position disposing said blade at an angle inclined rearwardly relative to the direction of the carrier movement; and blade moving means cooperating with said blades and operable responsive to arrival of each of said blades at a predetermined point above said end to move said blade from said retracted to said extended position, whereby said blade is `moved over said end to an outwardly and downwardly sloping position to allow solids carried by said blades to slide therefrom. v

8. In a classiiier, the combination of: a tank for receiving pulp containing solids to be separated and having a bottom upon which solids may settle from the liquid including an end portion curving upwardly and outwardly between a horizontally disposed portion and a vertically disposed portion which terminates in an endover which said solids may be discharged; a drag construction for moving such settled solids toward said end including a drag carrier movable through a path conforming with said curved bottom and a plurality of blades carried thereby in a position extending transversely of said bottom; drive means for moving said carrier in a direction to cause movement of said blades in a forward direction toward said end; means mounting said blades on said carrier for movement relative thereto between a retracted position in which the blade is maintained substantially normal to said bottom as lit is moved thereover and an extended position disposing said blade Iat an angle inclined rearwardly relative to the direction of the carrier movement; and blade moving means cooperating with said blades and operable responsive to arrival of each of said blades at a predetermined point above said end to move said blade horizontally outward from said retracted to said extended position, whereby said blade is moved over said end to an outwardly and downwardly sloping position to allow solids carried by said blades to slide therefrom.

9. In a classifier, the combination of a tank for receiving pulp containing solids to be separated and having a bottom upon which solids may settle from the liquid including an upwardly sloping portion terminating in an end over which said solids may be discharged; a drag construction for moving such settled solids toward said end including a drag carrier movable through a path conforming with said upwardly sloping bottom and a plurality of blades carried thereby in a position extending transversely of said bottom; drive means for moving said carrier in a direction to cause movement of said blades toward said end; means mounting said blades on said carrier for outward movement relative thereto from a retracted position to an extended position; blade` moving means cooperating with said blades and operable responsive to arrival of each of said blades ata predetermined point above said end to move said -blade relative to said carrier from said retracted to said extended position and over the end of said tank to move the solids carried by each of said blades beyond the confines of said tank; and means responsive to additional movement of said carrier for restoring each of said blades to said retracted position.

10. In a classier, the combination of a tank for receiving pulp containing solids to be separated and having a bottom upon which solids may settle from the liquid; a drag construction for moving such settled solids toward one end of said tank including a movable drag carrier and a plurality of blades carried thereby in a position extending transversely of said bottom; drive means for moving said carrier to cause movement of said blades toward said end; means mounting said blades on said carrier for movement relative thereto between a retracted position in which said blades are spaced inwardly from the bottom of said tank and an extended position; blade moving means cooperating with said blades and operable responsive to arrival of each of said blades at a predetermined point beyond said end to move said blade relative to said carrier from said retracted to said extended position and over the end of said tank to move the solids carriedl by each of said blades beyond the confines of said tank; and means associated with said mounting means for restraining each of said blades in said retracted position until said blade arrives at said predetermined point.

11. In combination with a classier which includes a tank having a bottom and a discharge end and a drag carrier for moving a plurality of drag blades through said tank to move solid materials resting on said bottom to said discharge end, a mounting means for mounting each of said blades on said carrier comprising: a supporting bracket having an elongated slot extending outwardly relative to said drag carrier; a pivot carried by said blade and slidably received in said slot; a stop member on said blade; a supporting member on said bracket having a supporting face engageable by said stop member to prevent pivotal movement of said blade about said pivot and having an end beyond which said stop may be moved as said pivot is slid outwardly along said slot; and means on said tank engageable by said pivot when said blade is moved to substantially said discharge end for sliding said pivot outwardly along said slot, whereby said blade is moved outwardly over the discharge end of said tank until said stop is moved beyond the end of said supporting face and is then pivotally moved by gravity to an outwardly and downwardly sloping position to permit said solids to slide therefrom.

12. In combination with a classifier which includes a tank having a bottom and a discharge end and a drag carrier for moving a plurality of drag blades through said tank to move solid materials resting on said bottom to said discharge end, a mounting means for mounting each of said blades on said carrier comprising: a supporting bracket having an elongated slot extending outwardly relative to said drag carrier; guide means on said blade slidably received in said slot; a shoulder formed on the inward end of said slot for engaging said guide means and restraining said guide means against outward sliding movement along said slot; and means responsive to arrival of said blade at a predetermined point beyond said discharge end for disengaging said guide means from said shoulder and sliding said guide means outwardly along said slot, whereby said blade is moved outwardly over said discharge end to convey said solids to a point outside the confines of said tank.

JOHN A. TRAYLOR.

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