US2426839A

US2426839A - Method and apparatus for cleaning or grading sand or the like

Info

Publication number: US2426839A
Application number: US489092A
Authority: US
Inventors: Alexander B Morris
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-05-29
Filing date: 1943-05-29
Publication date: 1947-09-02
Anticipated expiration: 1964-09-02

Description

Sept 2, 1947;

A. B. MORRIS METHOD AND'APPABATUS FOR CLEANING OR GRADING SAND OR THE LIKE Filed May 29 w 3 4 fi/llorrfs,

Patented Sept. 2, 1947 UNITED STATES OFF CE METHOD AND APPARATUS FOR CLEANING OR GRADING SAND OR THE LIKE Alexander B.Mo rris, San Antonio, Tex. e ieat on M 9, .3 Ser a 2 2 11 Claims.

This invention relates to a method of and-apparatus for cleaning and/or grading for size,

sand or other similar substances occurring as aggregations of separate granules.

One example of my invention consists in passing sand downward through a vertical column,

over systems of specially arranged baflles, and

counter-current to a stream of water flowing upward through the column; the dirt and extremely fine particles of sand passing out of the top of the column with the water, and the coarser particles working their way downward to a suitable sump, from which, as cleaned sand, they may be removed by pump, screw, elevator or other suitable device.

:Inorder to accomplish these purposes, 1 propose a vertical column into the bottomof which clean water is admitted at a rate of -flow such that the upward velocity of the stream through the column itself will be slightly greater than the rate at which the smallest particles desired horizontally, and through the spaces between them, in the places where there would be risers on a flight of steps, the upward-moving column of water passes. Each such step-bafilemoves the sand flowing downward over the steps fromone sidegof the column to the other, and the lowest stepof each baiiledischarges its stream of sand upontheuppermoststep of thebaflle immediately below it. 'The step-bafiies are so placed in the column thatthe edgesof-allthe stepson allthe bellies are parallel.

,Several such stepebaiiles ar placed in-the column above the water intake and below the point at which the dirty sand is introduced into the column. Thenumber of such bafiies to beused is dictated by the peculiaritiesofthe sand to be Washed, andbythe degree of thoroughness required in the washing. Th sand is introduced into the column in the form of a .thin sludge, and uponits entrance-it falls upon the topstep of the ,uppermost of the step-.baflles described above. As it pours from this step to the step be w i a u cessiv l d wnwa d a d ac oss th o n ial1 a thi urtain 3 395 51 1 as ndin s r am cf a e i uin be een the .ballles, in a direction roughly parallel with the steps. Ihis'water is thus imparted a turbulence which extracts from the curtain of sand, all the small particles and retains them in physical suspension, carrying them toward the top of the column. Of course, this turbulence washes out of the sand curtain many particles which are within the size range desired to be kept, and owing to the excess of dirt entering with the sand, the water around the sand intake may take on some colloidal properties and thus entrain many more particles which are desired in the finished product. For this reason, there are placed in the column, immediately above the sand intake, seV- eral more step-bafiles identical to those already described. Upon these baffles fall all large particles which may have been carried upward with the main water stream .due either to turbulence alone, to colloidal characteristics due to excess clays, or to both. some of these large particles and many which are close to the border line of tolerance for fineness will be carried to the top of the tower.

In .order to recover such of these particles as may be within the desired size range, there is placed in the column, above the uppermost of this second set of step baffles, a series of vertical baflles, or straightening vanes, the purpose of which .is to break up the turbulent main stream of water approaching the top of the column with its load of dirt and fine particles into anumber of small streams, and thusto remove the turbulenceand restore conditions of straight-line flow. ,Above these straightening vanes and occupying the ,top several feetof the column .is an empty chamber the full size of the column and unobstructed by any sort of bafiles, the purpose of which is to provide a settling chamber in which may settle out of the now quietly rising waterin thecolumn any particles of a size which may be desired in the product and which may have been ;carried upwardto that point. From the top of this settling chamber the water, dirt and silt pass .to waste. The ,rateof input of water is regulated so that the rate of flow upward through thesettling chamber will carry away to waste all ,particles below a certain predetermined size.

Owing to the degree ofturbulence impartedto the water in its passage between all these inclined baliies, and to the fact that its direction is .roughly parallelto th 'plane of the steps sufficient turbulence exists to remove and keep in uspension all the clays andfine sand particles. If the raw sand to be washed contains only a relatively small quantity of dirt, thesize of the column can be reduced just below the straightening vanes, and this reduced section carried upward through the settling chamber. In this way, the amount of water required to wash any particular sand can be greatly restricted, since the rate of flow through this part of the column controls the smallest size particle found in the finished product; and a reduction in column crosssection results in a reduced amount of water needed to yield the necessary upward rate of flow.

Some embodiments of the invention are illustrated in the accompanying drawing in which:

Fig. l is a vertical sectional view of one form of the apparatus.

Figs. 2, 3 and 4 are horizontal sectional views taken respectively on the lines 2-2, 8-3, 4-4,

of Fi 1.

Fig. 5 is a vertical sectional view of the upper end portion of a modification.

Referring to the drawing, 6 designates a vertical column, supported by a suitable foundation '1 of concrete or the like. The column may be of any preferred shape horizontally and as an example I have shown it of square cross-section. A pipe 8 is employed to introduce fluid, such as water, into the lower end of the column and it may pass through an inclined bottom 9 of the column and terminates immediately above the bottom.

Between the top and bottom of the column a conduit In is connected thereto for introducing the sand or the like into the column and this conduit rises, as indicated at H and terminates in a hopper 12 which extends upwardly to a higher elevation than the column.

The sand or the like to be treated travels to the hopper by any suitable means, such as an endless conveyor l3, and before dropping into the hopper may be saturated with water discharged through a nozzle It. The water introduced into the bottom of the column through the pipe 8 passes upwardly and is discharged from the top of the column through a pipe 15 leading to waste, and it will be understood that the water introduced through 8 and Ill will cause the water level at It in the hopper to be maintained at an elevation above the top of the column.

Within the column between the sand inlet pipe I0 and the bottom of the column there is a series of superposed bafiles IT, I8, I9, 20, and 2i dividing the interior of the column into a series of communicating compartments and arranged zigzag to cause solids to move downwardly in the column from one side thereof to the other. Each bafile consists of a number of strips or treads 22, inclined at about to the horizontal, each baiile being so arranged that it discharges sand from its lowest step up the top step of the next lower battle. The treads or strips which are supported by opposite walls of the column are spaced apart as indicated at 23 so that the rising water can pass through the openings between the steps. In order to obtain greater turbulence in the lower part of the column, I prefer to have the openings 24 between the steps of one or more of the lower bafiles smaller or narrower than the openings between the steps further up.

25, 26 and 2! designate other step-battles arranged above the sand inlet lEl. From the lower edge of-the lowest of these baiiles, there is a substantially vertical curtain 29 extending downward to within a short distance of the bottom step 3ll of'the baffle 21 and so placed that it provides a passageway 3i through which the relatively finer material caught on the baflies 25, 26, 2? can be returned to the system without becoming fouled by immediate mixture with the dirty input sand entering through It.

Above the baiile 25 I arrange vertical parallel straightening vanes 32 which are spaced apart and are connected to opposite walls of the column. Immediately above the vanes 32 there is an unobstructed settling chamber 33 at the top of the column from which the dirty water is discharged through the pipe Hi.

It should be observed that the lowest baffle 21 of the upper set is arranged so as to pass the sand in the same direction as the uppermost baffle 2! of the lower set. In other words these two baffies and the steps in them are parallel. I use this arrangement to provide for the quiet passage of fine material behind the curtain 29.

In operation, pit-sand is first rough screened to remove gravel, roots, lump clay, trash, etc., and then screened for the coarsest particles which it is desired to have in the product. The material passing this screen is then slushed into the column through l2, H, 18, and the water speed through 8 adjusted for removing from the sand thus introduced, all particles below the smallest size desired to be kept. A single passing through one column will yield a mixture almost totally free from particles of less than the minimum desired size. Obviously the heavier particles will gravitate downwardly and eventually lodge in a sump 3 t from which they may be removed by any suitable means (not shown).

If grading is desired, a series of similar columns should be used, the pit-sand being first passed through the one of smallest diameter, with the highest water speed through it. The product of this column will be the coarsest grade of sand. The discharge from the first column, instead of going to waste through pipe 15, is introduced into the input pipe I!) of the next column which should be of greater diameter so as to provide a lower water rate through the upper part of the column where actual sorting takes place. A small amount of water should be introduced through 8 at the foot of this column so as to provide a final wash in perfectly clean water. The material collecting in the sump 34 of this second column would be finer than that from the first column. If successively finer and finer grades of product are required, the discharge from the top of the second column can be introduced through the pipe H} of the third column and so on until all the sand is used up.

If the raw sand to be washed contains only a relatively small quantity of dirt, the size of the column can be reduced just below the straightening vanes as indicated at 35 in Fig. 5, and this reduced section extended upward through the height of the settling chamber as indicated at 36. In this way, the amount of water required to wash any particular sand can be greatly restricted, since the rate of flow through this part of the column controls the smallest size particle found in the finished product, and the reduction in cross-section results in a reduced amount of water needed to yield the necessary upward rate of flow.

For the grading of clean, dry sand, air can be used as the circulating medium and may be introduced through the pipe 8, the only changes required in the apparatus being of degree, such as the angle of slope of the steps of the bafiles and the amount of spac between them for use with a compressible medium like air. The space between the steps in each bafile would have to be increased toward the top of the-column.

The advantages of" this type of cleaning plant over mechanical cleaners now generally used are as follows The power required to operate this type of washer is only that needed todrive" a pump of suflicient size todeliver the water required;

There are no movingparts to wear or break, and' worn ba-files can be quickly replaced, thus reducing shut-down time.

The column can be constructed of' sewer pipe, wood-stave pipe, or anyother kind of" pipe, and thebafiles can be made ofcommon window glass. Thus, not only cana plant be constructed on any jobout of materials readily available; but steel working surfaces are not presented to the moving sand, so that, for glass making; this method of" washing and cleaning does not actually put iron cuttings into the sand.

The use of costly heavymoving machinery and the power plant to-operate it is'avoided.

As the sand progresses down the column it is continually entering cleaner and cleaner water, until it passes through perfectly clean water at the foot of the column. Thisprovides a better degreeof washing than any method depending upon agitation of the sand-body in acontainer from which the water flows over the top; or any method in which the sand-body is kneaded and turned over while water is sprayed upon it.

This method permits the highest degree of cleaning parallel with a minimum of water use. If water is-scarce, the height of the column need only be increased, sothat the sand makes more transits across the column on its way downward. Since it always endsupin perfectly clean water, itis only necessary to give it enough passes to secure any degree of Washing.

Thusthis method ishighly elastic, from an operating viewpoint. The only element of constancy needed to secure any degree of washing efilciency isconstancy ofdelivery of clean water. The: rate'of delivery of dirty sand may vary from zerot'o 100% column capacity from one minute to the next, without in any way impairing the degreeof cleannessobtained in the product. Overloading the column will result in loss of usable sand in the waste before the appearance of excessively fine particles in theproduct, and the operation of the plant isundisturbed by anything except-too rapid feeding so thatthe sand enters as heavy slugs. Such slugs will tend to carry dirt tO-th'e' lower parts: of the'column so-thatthe final wash. water will contain some clay particles; If slugging is avoided, a scrutiny of the particle size in the waste" will give an indication of whether or'not the column is being over-loaded. It is-not necessary to maintain any delicate degree of balance between water and sand input in order for thiscolumnto functionsatisfactorily.

From: the foregoing it will be understood that my apparatus depends upon the different rates of. settlement inwater of particles ofvarying size. Where-broken material of like kind and specific gravity is put into still water the large particles sink rapidly, and the rate of sinking decreases with the particle size, the. smallest particles requiring the longest time to settle.

If such loose material is'introduced-into' a tall column of upward rising water at the bottom of which a degree-of turbulence is maintained suffieient tokeep in suspension all particles smaller than a desired minimum, and at the top of which a rate of verticalnon-turbulent flow is maintained at a rate somewhat in excess efthe-rate of settlement ofthe smallest-particles desired to be retained, all smaller particlesthan-the predetermined minimumwill be carried toward; the topof the column and out with the-Waste, while al-lparticles of'greatersi'zel will be collected in the bottom of thecolumn.

In my apparatus this is accomplished by anarrangement ofb'affles or trays-set across the co'l umn; sloping at" a sufficient angl to cause the loose wet sand to flow'from one tray to: thenext below it; and each such bafile or tray'broken up into a plurality ofsteps, so that each: bafll'e': or tray presents the appearance of'a-small flight: of steps having inclined treads with no risers be tween them. The spaces between: the steps. on each baffle are equal, but this. distance; may be varied from baffle tolbaffle', so: that-a greater degree of turbulenoelm'ay be maintainedimthefb'ot tom of the column by having thesespace's. smaller inthe lower bafiles.- Y

The rate of water input is such. that, were there no: bafiles and. werethezst'reamof rising wa ter. not: disturbed; its average. speed: upward: would be sufiicient to carry out of the column all particles smaller" than a predetermined minimum; However; the int'er positionot thebafiles increases this speed betweemthemanu: causes a. turbulence which will scour out particles of the desired size even though the average speed of the water is lower than that which would: be necessary in an unobstructed column This turbulence is; eliminated in the top of the" colum by passing the waterthrough a vcell of. vertical bafiles :orstraig-htening. vanes, and by. maintaining in this: section of the column, a ratev of upward flow sufiioient' to) removeall particles of 'less than the predeterm'inediminimum'. In this top section of the column alliv particles of 'greater'size-than the-predeterminedlminimumtarelpermitted tosettle out and return to the system.

While Ihave disclosed some preferred methods of treating sand: or the like and certain practical embodiments for use inpracticing the methods; I am. aware that changes may bemadeinthe details of. the apparatus and in the method" steps without departing from the spirit ofthe invention as expressed: in the following claims.

What I claim and desire-to secure b Letters Patent is:

1. An apparatus of the character described comprising a substantially vertical column having an upper fluid outlet and a lower solids outlet, first means arranged at oneside of the-column for introducing loose material consistingof sol-id particles of various sizes, into the column between said outlet-s, a curtain arranged" in the column diametricallyopposite to-said first means and forming with the column a substantially Ver tical passageway, second means'for introducing a fluid stream into the column below said first means, a bafiie in the column between the first means and the fluid outlet and having a discharge end positioned at the top of said passageway, and a second bafile in the column between the first means and the second means and having a receiving end arranged adjacent to the lower end of said passageway, each of said baffles comprising a plurality of substantially parallel inclined steps spaced from one another and adaptedto direct solid particles downwardly from a side of the column towardtheoppositeside thereof whiIe fluid flows upwardly from said second means through the spaces between the steps and en-- trains light solid particles which discharge with the fluid through said fluid outlet.

. 2. ,An apparatus of the character described comprising a substantially vertical column having anupper fluid'outlet and a lower solids outlet, first means arranged at one side of the column for introducing loose material consisting of solid particles of various sizes, into the column between said outlets, a curtain arranged in the column diametrically opposite to said first means and forming with the column a substantially vertical passageway, second means for introducing a fluid, stream into the column below said first means, a baiile in the column between the first means and the fluid outlet and having a discharge end positioned at the top of said passageway, and a second baiile in the column between the first means and the second means and having a discharge end arranged adjacent to the lower end ofsaid passageway, each of said baflles comprising a plurality of substantially parallel inclined steps spaced from one another and adapted to direct solid particles downwardly from a side of the column toward the opposite side thereof while fluid flows upwardly from said second means through the spaces between the steps and entrains light solid particles which discharge with the fluid through said fluid outlet, both of said ballles being arranged in substantially parallel relation to one another.

3. An apparatus of the character described comprising a substantially vertical column having an upper fluid outlet and a lower solids outlet, first means for introducing loose material consisting of solid particles of various sizes, into the column between said outlets, second means for introducing a fluid stream into the column below said first means, spaced baffles in the column between said first means and each of said outlets, each of said bafiies comprising a plurality of substantially parallel inclined steps spaced from one another and adapted to direct solid particles downwardly from one side of the column toward the opposite side thereof while fluid flows upwardly from said second means through the spaces between the steps and entrains light solid particles which discharge with the fluid through said fluid outlet, and means arranged in the column between the first means and the fluid outlet and positioned above the baffles for preventing turbulence of the fluid before the latter reaches the fluid outlet.

4. An apparatus as claimed in claim 3 in which the turbulence preventing means consists of substantially vertical vanes arranged side by side and having their upper edges terminating at a substantially horizontal plane.

5. An apparatus of the character described comprising a substantially vertical column having an upper fluid outlet and a lower solids outlet, first means for introducing loose material consisting of solid particles of various sizes, into the column between said outlets, second means for introducing a fluid streaminto the column below said first means, spaced superposed bafiles in the column between said first means and each of the outlets, each of said baffles comprising a plurality of substantially parallel inclined steps spaced from one another and adapted to direct solid particles downwardly from one side of the column toward the opposite side thereof while fluid flows upwardly from said second means through the spaces between the steps and entrains light solid particles which discharge with the fluid through said fluid outlet, and substantially vertical vanes positioned in the column between said baflles and the top of the column and so arranged as to prevent turbulence of the fluid after it passes through the baflies.

6. An apparatus of the character described comprising a substantially vertical column having an upper fluid outlet and a lower solids outlet, first means for introducing loose material consisting of solid particles of various sizes, into the column between said outlets, second means for introducing a fluid stream into the column below said first means, spaced superposed bafiles in the column between said first means and one of said outlets, each of said baflles comprising a plurality of substantially parallel inclined steps spaced from one another and adapted to direct solid particles downwardly from one side of the column toward the opposite side thereof while fluid flows upwardly from said second means through the spaces between the steps and entrains light solid particles which discharge with the fluid through said fluid outlet, the upper end portion of the column being of less cross-sectional area than the portion of the column below, and a series of substantially vertical and substantially parallel vanes positioned in the upper portion of the column above the baffies and so arranged as to prevent turbulence of the fluid after it passes through the bafiles.

7. An apparatus of the character described comprising a substantially vertical column having an upper fluid outlet and a lower solids outlet,- first means for introducing loose material consisting of solid particles of various sizes, into the columnbetween said outlets, second means for introducing a fluid stream into the column below said first means, a first set of superposed baffles arranged in zigzag formation in the column between said first means and the fluid outlet, a' second set of baiiles arranged in zigzag formation in the column between the first and second means, each baflie comprising a plurality of substantially parallel inclined steps spaced from one another and adapted to direct solid particles downwardly from one side of the column toward the opposite side thereof while fluid flows upwardly from said second means through the spaces between the steps and entrains light solid particles which discharge with the fluid through said fluid outlet, and means in the column above the first set of bafiles for eliminating turbulence in the fluid as it flows toward said fluid outlet. 7 8. An apparatus of the character described comprising a substantially vertical column provided internally with a series of superposed bafiles dividing the interior of the column into a series of communicating compartments, a first outlet for discharging liquid from the uppermost compartment, a second outlet for discharging solids from the lowermost compartment, first means for introducing loose material consisting of solid particles of various sizes, into one of the compartments between the uppermost one and the lowermost one, second means for introducing a liquid stream into the lowermost compartment, each baffle comprising a plurality of substantially parallel inclined steps spaced from one another and adapted to direct solid particles downwardly and transversely of the column while liquid from the second means flows upwardly through the column and through the spaces between the steps, and substantially vertical vanes positioned in the column between said baflies and the top of the column and so arranged as to prevent turbulence of the fluid after it passes through the bailles.

9. An apparatus of the character described, comprising a substantially vertical column having an upper fluid outlet and a lower solids outlet, first means arranged at one side of the column for introducing loose material consisting of solid particles of Various sizes, into the column between said outlets, a curtain arranged in the column and forming therewith a substantially vertical passageway, second means for introducing a liquid stream into the column below said :first means, a bafiie in the column between the first means and the fluid outlet and having a discharge end positioned at the top of said passageway, and a second baffle in the column between the first means and the second means and arranged adjacent to the lower end of said passageway, each of said bafiles comprising a plurality of substantially parallel inclined steps spaced from one another and adapted to direct solid particles downwardly and transversely of the column while liquid flows upwardly from said second means through the spaces between the steps and entrains light solid particles which discharge with the liquid through said fluid outlet.

10. In a method of the character described, passing loose material consisting of solid particles of various sizes downwardly through a series of communicating compartments, simultaneously passing a liquid upwardly through said compartments and thereby scouring the particles, maintaining said liquid in the lower compartments at a degree of turbulence sufficient to keep in suspension all particles smaller than a desired minimum, and maintaining non-turbulent flow of the liquid at the uppermost compartment whereby all particles smaller than a predetermined minimum will be discharged with the liquid from the uppermost compartment while all particles of greater size will sink through the liquid and be discharged from the lowermost one of the compartments.

11. In a method of the character described passing loose material consisting of solid particles of various sizes downwardly through a series of alternately arranged spaced bafiles and compartments, passing liquid upwardly successively through the compartments and baffles and thereby scouring the particles, maintaining the liquid in the lower compartments at a degree of turbulence sumcient to hold in suspension all particles smaller than a desired minimum, and maintaining non-turbulent flow of the liquid in the uppermost compartment whereby all particles smaller than a predetermined minimum will be carried by the liquid out of the system while all larger particles will sink through the quietly rising liquid and return to the system to be recovered.

ALEXANDER B. MORRIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 168,177 Ordway Sept. 28, 1875 843,783 Wilson Feb. 12, 1907 1,861,248 Stebbins May 31, 1932 1,491,429 Stebbins Apr. 22,1924

271,604 Cook Feb. 6, 1883 1,650,727 Stebbins Nov. 29, 1927 FOREIGN PATENTS Number Country Date 449,731 Germany Sept. 28, 1927 451,942 Great Britain Aug, 11, 1936 468,212 Great Britain June 28, 1937 24,968 Great Britain 1907 166,278 Great Britain July 21, 1921