US2760634A - Method and apparatus for hydraulic classification involving settling - Google Patents

Description

Aug. 28, 1956 w. E. SAXE 2,760,634

METHOD AND APPARATUS FOR HYDRAULIC CLASSIFICATION INVOLVING SETTLING Filed Dec. 18, 1951 5 Sheets-Sheet l M1. 75/? .5 SAXE Aug. 28, 1956 w. E SAXE ,7

METHOD AND APPARATUS FOR HYDRAULIC CLASSIFICATION INVOLVING SETTLING Filed Dec. 18, 1951 3 Sheets-Sheet 2 /6 F7. PER. MIN.

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f/vvs/vroe: M47351? 5. SAXE Aug. 28, 1956 w. E. SAXE METHOD AND APPARATUS FOR HYDRAULIC CLASSIFICATION INVOLVING SETTLING 5 Sheets-Sheet 3 Filed Dec. 18 1951 m m M J.

'MLTEP E. 54x5 United States Patent METHOD AND APPARATUS FOR HYDRAULIC CLASSIFICATION INVOLVING SETTLING Walter E. Saxe, Pasadena, Calif., assignor to The Conveyor Company, Inc., Los Angeles, Calif., a corporation of California Application December 18, 1951, Serial No. 262,261

20 Claims. (Cl. 209208) This invention relates to hydraulic classifiers, more particularly to the type employing progressive settling.

In many classification jobs relatively large quantities of Water are required to be handled in conjunction with solids to be removed or classified. One such situation is encountered in connection with large construction jobs Where huge amounts of sand, and the like, are required to be used and large quantities of wash water or other accompanying water must be handled. Especially where a very large proportion of water is encountered, very large classifier equipment of conventional types ordinarily must be employed and correspondingly large areas must be provided.

An object of the invention is to provide a method and a classifier for handling very conveniently large amounts of water with limited equipment and in limited areas.

A particular object of the invention is to provide a hydraulic classifier, and a method for hydraulic classification wherein settling of such materials as sands is accelerated by withdrawal of water in various zones, so that the rate of flow of the introduced feed is succesively reduced in various zones, it being thereby possible to shorten the respective zones to shorten very materially the length of the whole apparatus required for a given operation.

Another object of the invention is to provide a hy draulic classification system which may serve in an initial stage of separation, in the case of sand washing and separating procedures, for the removal of clear or approximately clear water which might be recirculated for immediate reuse in such washing system.

It is a further object of the invention to provide a hydraulic classification system in which solids, sands for example, may be classified by separation in successive zones in which settling may be accelerated by withdrawal of Water, for example clear water, to reduce the flow rate through the apparatus, and in which water might be introduced in any given zone to accomplish hindered settling should that be necessary to produce any desired separation of classification effect.

Another object of the invention is to provide in hydraulic classification apparatus for passage of pulp across a succession of zones by overflow from one zone to another in order to accomplish settling in successive zones with removal of solids from the bottoms of successive zones, water being separately removable from various zones to slow down overflow therefrom, it being also a particular object in such a procedure to avoid communication between the bottoms of the zones.

Other objects of the invention and various features of construction will become apparent to those skilled in the art upon reference to the accompanying drawings wherein certain embodiments are illustrated.

In the drawings:

Fig. l is a longitudinal vertical section through one form of apparatus embodying the invention and istaken approximately as indicated by the line 1-1 of Fig. 2;

Fig. 2 is a plan view of the apparatus of Fig. 1;

Fig. 3 is an elevational, longitudinal, diagrammatic illustration of the apparatus of Fig. 1;

Fig. 4 is an enlarged vertical cross section taken approximately from the line 44 of Fig. 2; and

Fig. 5 is a vertical cross-sectional detail taken on the line 5-5 of Fig. 2.

The apparatus illustrated comprises an elongated classifier tank generally indicated at 19 which is supplied at one end with pulp feed means F. The tank lll includes an inclined front end wall 11, elongated side walls 12, and a rear end wall 13. If the apparatus has substantial width, as in the form illustrated, it may be provided with a plurality of longitudinally extending partition walls 14 which divide the tank into a plurality of longitudinal runs. The bottom of the tank 10 is formed of a plurality of transverse, inclined bottom wall members 15 which provide between them and the end walls 11 and 13 a plurality of downwardly tapering transverse classifier pockets 16, each pocket 16 having at its bottom a transverse, horizontal narrow wall 18. Thus each pocket 16 has an inverted truncated shape.

As best illustrated in Figs. 1 and 3, the body portion of the tank space between the vertical walls 12 and 14 and above the bottom walls 15 and 18 is divided into a plurality of successive settling zones 20, 22, 23 and 24, each of these zones overlying two of the tapered pockets 16. These zones are separated from each other by upstanding transverse divider walls 25 which rise from the juncture of corresponding pairs of inclined bottom walls 15 and terminate below the liquid level in the apparatus. Desirably the heights of the divider walls 25 are successively lower as the discharge end of the tank is approached. These divider walls 25 may be connected in any suitable manner to the upper ends of the respective walls 15 and to the inner faces of the vertical walls 12 and 14. In some instances, depending upon the nature of the materials in the plup being classified, it may be desirable to employ an auxiliary transverse vertical divider wall 26 to divide each zone 20 into two smaller zones 20a and 20b. Each divider wall 26 between the respective vertical walls 12 and 14 may be removable if desired, the wall 26 being retained between pairs of vertical guides 28 secured to the opposing faces of the walls 12 and 14. In each instance the respective divider wall 26 may rest upon the joint at the upper ends of the respective walls 15.

For the purpose of removing solids, such as sand, which settle in the respective pockets 16, each transverse bottom wall 18 in each of the runs between the vertical walls and partitions 12 and 14 is provided with a depending discharge pipe 30 carrying an adjustable valve 31 and a rotary deflecting discharge member 32 which may be in the form of a 45 elbow, so that sand or other materials to be discharged may be deflected into a corresponding chute 33 leading as by way of a down spout 33a to a main waste chute 34, or into a corresponding chute 35 leading to one or more product chutes 36, as by way of a down spout 35a. The chutes 34 and 36 are respectively provided with appropriate down spouts 342a and 36a for disposition of. the waste materials and products as required.

The discharge end of the tank 14 adjacent the rear wall 13, communicates with another waste down spout 38 which leads from the lowest point of an overflow launder 40 which extends around three sides of the discharge end of the tank opposite the adjacent portions of the walls 12 and 13 which have been reduced in height to provide upper overflow edges 41 and 42 at the top of the corresponding end zone 2.4. These overflow edges 41 and 42 establish a liquid level which is generally indicated at 43 in Figs. 1 and 3, which lies above the tops of the divider walls 25, and which is maintained by a pulp supply introduced horizontally at the feed end of the tank by the feed mechanism F.

The feed mechanism F is shown as including a bottom wall 45 below the liquid level 43, which bottom wall 45 may be equipped with an adjustable lip or shelf 46 whose forward edge establishes the point over the zone 28 at which settleable solids begin to drop. The point of dis-- charge as determined by the outer edge of this slide, coupled with the rate of flow of feed, may be used to establish the character of the solids which settle in the zone 20 as a whole, or in the subdivisions 29a and 20!) thereof if the auxiliary divider wall 26 is employed, as more fully to be described hereinafter. A vertical back wall 47 of the mechanism may be used together with appropriate end walls and an extension of the front wall 11 of the tank 10 to define the pulp-receiving portion of the feeder. The lower edge of the wall 47 is elevated above the shelf 46 to establish a discharge opening 48 which may at the same time define the liquid level 43. The interior of the feed mechanism F within the mentioned upstanding walls is supplied with pulp by down spouts 59, there being preferably one such down spout 59 feeding into each of the longitudinal runs between the side walls 12 and the partition walls 14. These down spouts are arranged in pairs in the form shown and each pair is supplied by a feed trough 52 (Fig. 2). The chamber portions within the feed mechanism to which the respective down spouts 50 lead are preferably separated as by means of partitions 54 aligned with the upstanding partitions 14 in the tank 10. Splitters are used in the troughs S2 to divide the feed to the respective down spouts 50 as required. These splitters may be in the form of vertical plates 55 which may swing upon vertical pivots 56 to appropriate positions of adjustment and be retained in such positions by any retaining means as indicated at 58 (see Fig. By these means the desired amount of feed pulp may be introduced into each of the runs between the side walls 12 and partition walls 14, the djustable shelf 46 being set forward to effect the required dropping out of the oversize solids.

Regulation of the settling of the solids, particularly the accelerated settling of this improvement, is governed by the well known principle that given particles will settle in a running stream at the same vertical rate as they would in still water. Of course, the faster the rate of the running stream, the greater the horizontal distance required for a given particle to settle a given vertical distance, and conversely, if the stream rate is reduced, the amount of vertical settling will be accomplished in a shorter horizontal distance. Therefore, if we have a very large volume of feed material to handle, which at the same time requires a higher rate of initial horizontal flow so that such amount of material may be handled in a given period, we may shorten our-ap paratus and increase its capacity if we can remove a substantial proportion of the accompanying water in some or all of the settling zones so as progressively to slow up the horizontal flow, while at the same time providing for withdrawal of adequately dewater ed solids from the bottoms of the pockets of the apparatus.

This function of removing water from various settling zones, whereby progressively to reduce the rate of flow along the apparatus and to increase settling efficiency, has

been ccomplished by providing below the liquid level in each settling zone or settling pocket downwardly directed water-trapping means which provide at the same time means for directing settling solids downward into the bottoms of the pockets. Such means in the form illustrated are provided by inclined hood plates 60 (Fig. 1) having vertically depending flanges 61 which serve to direct the settling solids downward. The inclined plates 66 are conveniently attached to the respective upstanding transverse divider walls 25, their ends joining the respective upstanding side walls 12 and longitudinal partition walls 14. These partitions thus provide between the inclined hood plates 60 and the adjacent portions of the divider walls 25 water-trapping chambers 62 from which water may be removed if desired without picking up any of the settling solids, unless such of those settling solids as have a lower settling rate are desired to be removed by such removed water, in which case the withdrawal rate may be increased. In order to withdraw water from any water-trapping chamber 62, a horizontal pipe 64 leads from each of such chambers transversely through respective partition walls 14- and. side walls 12 to collector boxes 65 at the'sides of the apparatus, as is seen in Figs. 2 and 4. The outer end of each pipe 64 in its collector box 65 is provided with an adjustable valve 66 so that the rate of water passing through the valve, under the hydraulic head within the tank 10, may be varied as required. 'As shown, four pipes 64 lead to each collector box 65 and a down spout 63 drains the water into the respective waste chute 33.

From the foregoing it will be apparent that, if a large volume of pulp is fed horizontally into the tank 10 in the direction of its length from the feed mechanism F at an initial discharge rate, the withdrawal of significant amounts of trapped Water through the pipes 64 from within any or all of the water-trapping chambers 62, the rate of flow of the pulp continuing from zone 26 to the successive zones 22, 23 and 24, will be successively decreased. As a consequence the amount of solids settled in each of the zones, even with a large volume of pulp feed, is much greater than if the flow rate along the length of the apparatus was uniform. Thus, the how rate can be cut down so rapidly, even with excellent classification, that an apparatus of half the normal length, for example, may be relied upon for the same hourly through-put.

By way of exempliiication, and having particular reference to Figs. 1 and 3, a pulp feed of about 360 cubic feet per minute may be introduced into a given apparatus to have an average speed across the zoneZtl of about 40 feet per minute horizontally. Where each of the zones Zll, 22, 23 and 24 has a length of about 8 feet, the 40-foot per minute stream requires about twelve seconds to pass across the zone 20 from the feed shelf 46 to the first divider wall 25. Thus, oversize or other solids having a fast settling rate, for example, 5 feet per minute, will drop out in the zone 20 before reaching the first divider wall 25 Where the distance between the liquid level 43 and the top of such wall 25 is 12 inches, or 2 feet per minute from the bottom of the flowing stream (assuming a six-inch thickness of the flowing stream). Since sand of about 200 mesh falls about one foot per minute, no ZOO-mesh sand would fall in the zone 20 but would pass on over the first wall 25. Of course, water withdrawn through the pipes 64in the first water-trapping chamber 62 will have slowed down the average rate of flow from the initial introduction rate. Also withdrawal of water from the two water trapping chambers 62 in the zone 22 may be relied upon to reduce the average flow across the top of the zone 22 to about 33 feet per minute. In this zone settling material will accumulate which has a dropping rate of between 3 feet and 5 feet per minute. Similarly in the zone 23 water withdrawal through the pipes 64 may be relied upon to reduce the average flow rate at the top of the zone to 24 feet per minute, as a result of which materials having a settling rate of 2% feet to 3 feet per minute will drop out. In the last zone 24 water withdrawal may be. suf- 'ficient to slow up the average rate at the top of the zone to 16 feet per minute so that the materials that drop out will have a falling rate of one (1) foot to 2 /2 feet per minute.

It will be apparent that the withdrawal of water in the various water-trapping chambers 62 through their take-oil pipes 64 has the effect of producing a rising water column below the respective chamber 62 as the water is removed through the pipes 64. The speed of these rising columns will vary in accordance with the adjustment of the valves 66. For example, in connection with the example just given regarding average flow rates across the tops of the zones 20, 22, 23, and 24, the rise of the water column into the first chamber 62 in the zone 20 may be at the rate of 5 feet per minute; in the zone 22 the rate of the rising water column to both chambers 62 may be 4 feet per minute; in the zone 23 the rate of rise of the water columns may be 3 feet per minute; and in the zone 24 the rate of rise into the first chamber 62 may be 2 feet per minute, but in the last chamber against the end wall 13, it might be desirable, especially for the purpose of slirnes carry-over, that the rate be only about one (1) foot per minute.

It will also be apparent that the rate of water withdrawal from any one of the Water-trapping chambers 62 may be made great enough to pull out the more slowly settling fraction of the sand dropping into the respective pocket 16. With this means, a still further classification could be accomplished upon dewatering of the material withdrawn. It will also be appreciated that, by increasing the amount of water withdrawn through the discharge valves 31 at the bottom of each pocket 16, the flow rate from the feed end of the apparatus to the discharge end of the apparatus may be further reduced.

If desirable further to regulate classification, it would be possible to cut otf all water removal through any one or more of the pipes 64 so that there would be no underlying rising column, or even to inject water through such pipe or pipes 64 so as to produce hindered settling in the respective pockets 16.

In actual practice it has been found possible with some pulp feeds so to regulate the discharge of oversize particles into the first zone 20 and so to regulate the withdrawal of water through the pipes 64 thereof that absolutely clean water may be taken ofi through the pipes 64 from the first zone in order that such clean water may be immediately available for reuse in the washing of fresh batches of sand. As previously indicated, if it is deemed necessary to segregate quickly certain particles which may be deemed oversize, the auxiliary upstanding divider wall 26 may be positioned as shown whereby to form the subdivisions 20a and 20b of the zone 20.

I claim as my invention:

1. Classifying apparatus including: a tank elongated in a direction of pulp flow; means for feeding pulp horizontally into one end of said tank; means for discharge from the other end of said tank; transverse partition means dividing the lower portion of said tank into a plurality of transverse receiving pockets at the bottom thereof, said pockets being provided at their bottoms with means for regulated discharge of settled solids; trapping means adjacent some of said pockets and elevated with respect thereto but below the normal pulp level in said tank for taking off quantities of pulp from the respective pockets at positions above the bottoms thereof and establishing corresponding movement of liquid within such trapping means; and flow means leading from said trapping means to the exterior of said tank for effecting liquid flow from said trapping means and from said tank.

2. Apparatus as in claim 1 wherein said trapping means are in the form of downwardly faced, inverted pockets communicating with the respective receiving pockets above their bottoms and effecting vertical liquid movement in the respective trapping mean-s.

3. Apparatus as in claim 1 wherein said means for feeding pulp horizontally is adjustable with respect to the first receiving pocket to vary longitudinally of the apparatus the position of discharge of the pulp feed.

4. Apparatus as in claim 1 wherein said transverse dividing means terminate below the top of the apparatus to provide for overflow between pockets adjacent their tops.

5. In combination in classifying apparatus for mineral pulp feed: an elongated tank; means for feeding pulp into one end of said tank; overflow discharge means at the other end of said tank; means transversely dividing said tank into a succession of classification zones and providing for overflow from one zone to succeeding zones; means for separating settled solids from said zones; means for separating water from certain of said zones; and other means disposed at intermediate positions below the overflows from said zones, for selectively taking ofi separated water from certain of said zones and delivering such water exteriorly of said tank to reduce the rate of fiow between zones and successively accelerate settling.

6. A combination as in "claim 5 wherein said means for separating water and taking off se arated water include means for segregating water from settling solids in the respective zones and means for withdrawing such segregated wafer therefrom simultaneously with settling of such solids in proportion to increase solid-settling in the respective zones.

7. Classifying apparatus including: an elongated tank means; longitudinally extending vertical partitions dividing said tank means into a plurality of lon itudinal runs, each partition extending substantially the full length of the tank means and each longitudinal run extending substantially the full length of the tank means; transversely disposed divider means dividing said runs into successive settling zones; discharge means for removing settled solids from the lower portion of each zone; means for trapping out and removing separated water from intermediate positions above the discharge means of various of said zones and removing it from said tank means to regulate flow rates across said zones; means for feeding horizontally and longitudinally into said runs pulp which carries solids to be classified; means supplying pulp to said feeding means; and means for proportioning the pulp being passed from the supplying means to said runs.

8. Classifying apparatus as in claim 7 including means establishing a water level in said tank means above said zones, said intermediate positions being located below said water level and above the bottom of the tank means.

9. Classifying apparatus as in claim 7 wherein said trapping means are in the form of downwardly faced pockets communicating with the respective zone and effecting vertical liquid movement in the respective trapping means.

10. A method of classifying mineral pulp and the like including: passing such a pulp containing settle'able solids having varying settling rates over a series of settling zones in a system; withdrawing liquid from some of such zones at positions therein intermediate the bottoms thereof and the pulp levels therein and removing the withdrawn liquid from the system for successively lowering the flow rate of the pulp and accelerating settling of solids of varying sizes in successive zones; and withdrawing settled solids from some of such zones.

11. A method as in claim 10 including withdrawing liquid from at least one of said zones at a rate suincient to remove therewith solids of slower settling rate than others normally settling in the respective zone.

12. A method for accelerating classification of pulp solids and increasing capacity, including the steps of: flowing a pulp containing solids to be classified through a succession of settling zones; efiecting separation of water from settling solids in certain of said zones at positions intermediate the tops and bottoms of such zones; withdrawing from the system water so separated from said settling solids, thereby successively reducing the rate of pulp flow through such zones and accelerating solidsaccumulation in the respective zones; and separately removing from various zones solids resulting from such accelerated settling.

13. A method as in claim 12 including withdrawing liquid from at least one of said zones at a rate low enough to prevent removal therewith of settling solids.

14. In combination in classifying apparatus for mineral pulp feed: an elongated tank; means for feeding pulp into one end of said tank; overflow discharge means at the other end of said tank; means transversely dividing said tank into a succession of classification zones and providing for overflow from one zone to succeeding zones; means for separating settled solids from said zones; means for separating Water from certain of said zones; and other means for selectively taking off separated water from said certain of said zones and delivering such water exteriorly of said tank to reduce the rate of flow between zones and successively accelerate settling, said feeding means including means for directing the feed material horizontally and longitudinally of said tank and said directing means being adjustableto release contained solids at varying distances across the top of the first of said classification zones and control the solids settling in said first zone under a given rate of pulp feed.

15. A combination as in claim 14 including auxiliary dividing means across said first zone for further classifying solids settling therein.

16. In combination in classifying apparatus for mineral pulp feed: an elongated tank; means for feeding pulp into one end of said tank; overflow discharge means at the other end of said tank; means transversely dividing said tank into a succession of classification zones and providing for overflow from one zone to succeeding zones; means for separating settled solids from said zones; means for separating water from certain of said zones; and other means for selectively taking off separated water from said certain of said zones and delivering such water exteriorly of said tank to reduce the rate of flow between zones and successively accelerate settling, said means for separating Water and taking off separated water including means for segregating water from settling solids in the respective zones and means for withdrawing such segregated water therefrom simultaneously with settling of such solids in proportion to increase solid-settling in the respective zones,

said means for separating water being trap means disposed below the level of pulp in said tank passing to said overflow discharge. t

17. A method for accelerating classification of pulp solids and increasing capacity, including the steps of: flowing a pulp containing solids to be classified through a succession of settling zones; effecting separation of water from settling solids in-certain of said zones at positions intermediate the tops and bottoms of such zones; withdrawing from the system waterso separated from said settling solids, thereby successively reducingthe rate of pulp flow through such zones and accelerating solidsaccumulation in the respective zones; separately removing from various zones solids resulting from such accelerated settling; eiiecting downward movement in certain of said zones of pulp and settling solids; and changing the direction of water flow in certain of said zones to produce rising water columns while settling of solids continues in such zones, said withdrawing of separated water being from such rising columns.

18. A method for accelerating classification of pulp solids and increasing capacity, including the steps of: flowing a pulp containingsolids to be classified through a succession of settling zones; effecting separation of water from settling solids in certainof said zones at positions intermediate the tops and bottoms of such zones; withdrawing from the system water so separated from said settling solids, thereby successively reducing the rate of pulp fiow through such zones and accelerating solidsaccumulation in the respective zones; separately removing from various zones solids resulting from such accelerat'ed settling; and overflowing pulp from the top of each zone to the top of a succeeding zone.

19. A method of classifying mineral pulp and the like including: passing such a pulp containing settleable solids having varying settling rates over a series of settling zones in a system; withdrawing liquid from some of such zones at positions therein intermediate the bottoms thereof and the pulp levels therein and removing the withdrawn liquid from the system for successively lowering the flow rate of the pulp and accelerating settling of solids of varying sizes in successive zones; and withdrawing settled solids from some of such zones, the withdrawn liquid being withdrawn as rising columns at selected speeds whereby the solids content of such liquid is controlled.

20. A method for accelerating classification of pulp solids and increasing capacity, including the steps of: flowing a pulp containing solids to be classified through a succession of settling zones; ettecting separation of water from settling solids in certain of said zones at positions intermediate the tops and bottoms of such zones; withdrawing from the system water so separated from said settling solids, thereby successively reducing the rate of pulp flow through such zones and accelerating solids-accumulation in the respective zones; and separately removing from various zones solids resulting from such accelerated settling, said separation of Water from settling solids including withdrawing water in rising co1- umns at regulated speeds controlling the solids content of the water.

References Cited in the file of this patent UNITED STATES PATENTS 1,056,952 Smith Mar. 25, 1913 1,709,365 Newsom Apr. 16, 1929 1,715,693 Bird June 4, 1929 1,794,374 Graham et al Mar. 3, 1931 1,843,854 Waldron et al Feb. 2, 1932 2,590,756 Colin et a1. Mar. 25, 1952 FOREIGN PATENTS 238,158 Great Britain Aug. 13, 1925 945,200 France Apr. 27, 1949

Claims (1)

1. CLASSIFYING APPARATUS INCLUDING: A TANK ELONGATED IN A DIRECTION OF PULP FLOW; MEANS FOR FEEDING PULP HORIZONTALLY INTO ONE END OF SAID TANK; MEANS FOR DISCHARGE FROM THE OTHER END OF SAID TANK; TRANSVERSE PARTITION MEANS DIVIDING THE LOWER PORTION OF SAID TANK INTO A PLURALITY OF TRANSVERSE RECEIVING POCKETS AT THE BOTTOM THEREOF, SAID POCKETS BEING PROVIDED AT THEIR BOTTOMS WITH MEANS FOR REGULATED DISCHARGE OF SETTLED SOLIDS; TRAPPING MEANS ADJACENT SOME OF SAID POCKETS AND ELEVATED WITH RESPECT THERETO BUT BELOW THE NORMAL PULP LEVEL IN SAID TANK FOR TAKING OFF QUANTITIES OF PULP FROM THE RESPECTIVE POCKETS AT POSITIONS ABOVE THE BOTTOMS THEREOF AND ESTABLISHING CORRESPONDING MOVEMENT OF LIQUID WITHIN SUCH TRAPPING MEANS; AND FLOW MEANS LEADING FROM SAID TRAPPING MEANS TO THE EXTERIOR OF SAID TANK FOR EFFECTING LIQUID FLOW FROM SAID TRAPPING MEANS AND FROM SAID TANK.

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