US2006119A - Apparatus for the separation of dry materials - Google Patents

Description

June 25, 1935. J. N. sTElNMETzER APPARATUS FOR THE SEPARATION OF DRY MATERIALS Filed Aug. 16, 1935 5 Sheets-Sheet 1 June 25, 1935. J. N. sTElNMETzER APPRATUSFOR THE SEPARATION OF DRY MATERIALS Filed Aug. 16, 1955 5 shets-she'et 2 June 25, 1935. J. N. s'r'l-:INMETZR 2,006,119

APPARATUS FOR THE SEPARATION OF DRY MATERIALS Filed Aug. 16, 1935 5 Sheets-Sheet 3 W. 077W# M June 25, l1935. '-J. N. s-rElNMETzER l 2,006,119

APPARATUS-FOR THE SEPARATION OF DRY MATERIALS Filed ug. 16, 1935 5 Sheets-Sheet 4 l l l I I June 25, 1935. J. N. sTElNMETzER I APPARATUS FOR'THE SEPARATION OF DRY MATERIALS 5 Sheets-Sheet 5 Filed Aug. 16, 193:5

J gIZ'enM-e-/jef Patented June 25, 1935 APPARATUS FOB THE SEPARATION F DRY MATERIALS Joseph Nicholas Steinmetxer, Watermael,

Belgium Application August 16, 1933, Serial No. 685,478 In Great Britain Allgust 10, 1932 Claims.

This invention relates to apparatus for the separation of solid materials of different specific gravity and more particularly to separation by stratification in which the dry materials are made 5 to flow along the surface of a trough as a stream in fluid form.

The process carried out by this apparatus is of special advantage for thedry cleaning of coal but may be applied to the dry separation of ores, and the like, and is principally concerned with the separation of materials without previous grading into sizes, but mayv be applied with like advantage to the separation of sized material.

In the separation of dry materials use has been made `of the combined actions of a current of air and a reciprocatcry, vibratory, or jigging motion applied to a bed of materials, which combined actions are limited in efficiency by reason of the,`

high pressure and velocity of the air currents and the alternating character of the motion, the eiliciency being least in respect of the separation oi materials whose particles are small in si'ze.

One reason for this low eiciency is that the bed of materials under these known combined actions becomes only partially fluid in condition, which partial fluidity is obtained for its greater part by the air action.

The object of the present invention is the provision of means whereby a stream of solid materials is brought to the condition of a smoothly flowing liquid in which one particle rolls freely over another and permits of the movement within the mass necessary for a perfect stratification in accordance with the specific gravity. I

The invention consists mainly in apparatus for separating a mixture of solid materials having differing specific gravities, wherein a vessel containing the mixture is constrained to move in a continuously curved non-reciprocating path to reduce its contents to an approximation to a perfect liquid and so allow of unhindered gravitational separation of the parts'of the mixture.

The invention also consists in apparatus for carrying out the method according to the preceding paragraph wherein the frequency of the motion cycles may be of the order of 1000 cycles per minute or more.

The invention also consists in apparatus sub- 3 stantially as herein described.

The present invention combines the actions of a rolling motion with an air current upon a stream lof material, which converts it into a highly effective fluid con-dition very closely resembling a flow- 5 ing liquid. It is found that material in this :duid

state ows easily down a trough when inclined very slightly from the horizontal.

By the addition of a small air current passing upwardly through the mass and acting in combination with the motion, it is found that the friction between particles is still further reduced, and the highest eillciency obtained Whilst the upward flow of air also resists the tendency of the :liner particles to fall through the interstices of the mass and serves to maintain the mass of material as a 10 uniform mixture of sizes and thus assist the desired stratification action. p I

The apparatus comprises a trough or channel having a bottom constructed of pervious metal or any other suitable material and provided with upstandingsides or walls. This trough is longer than it is wide and immediately beneath it is an air chamber connected to the trough. This chamber is provided with a port or ports suitably arranged for connecting it to an air compressor or fan by means of a ilexible material.

A foundation frame is provided upon which the trough is supported through the medium of springs which consist of straight steel bars of suitable and adjustable length and preferably of circular section arranged in horizontal position and having their axes at right angles to the long dimension of the trough.

The foundation frame may be of any suitable /form of rigid construction adapted for the attachment of one or more pairs of horizontal springs. Each spring has one end rigidly attached to the frame by means of a suitable bracket, the other end being similarly attached to the side of the trough. Each pair of springs has its axes in a straight line, one spring being placed at either side of the trough.

The springs govern and control the motion imparted to the trough containing the materials being treated. These springs, by virtue of their circular form of section and equal length deflect equally in all radial directions about their axes when subjected to uniform load values. When subjected to centrifugal force such as is derived from an unbalanced body revolving at high speed about an axis either coincident or parallel to the spring axis they respond by virtue of their equal radial deflections, and produce a motion at their extremities of true circular form for all such speeds of rotation as are within therange of their natural periodic time of vibration, and this motion will be uniform for each speed of rotation of the body and truly in phase with its motion.

Mounted .upon this shaft and attached thereto an out-of-balance weight is provided. Forqconvenience, this out-of-balance weight may be provided in two pieces, one of which may be attached to each end of theV shaft. Provision may also be Vmade for regulating the'moment value of the off-balance weight, which may be of any known device.

The shaft is made to rotate by means of suitable -driving lmechanism which in a preferred form consists of a pulley or pulleys attached to the shaft driven by a strap from a motor or other suitable power source. Alternatively an electric motor may be constructed about the shaft as a simple and eifective driving means.

When a mass of materials of mixed sizes is subjected to motion, there is a tendency for the -particles of small size to fall through the mass sary value to exert an equalv and opposite tendency. l

-In the case where two liquids of different specific gravity which do not chemically act upon each other or become one solution are contained in a common vessel, it is known that they stratify into separate layers accordingto their specific gravity because of the almost frictionless property of their liquid state. Similarly, if a like mixture of solids were brought into the same state by reducing to a minimum the obstructing friction, they would stratify into separate layers according to their speciiic gravities ina like manner to liquids.

By this invention a condition of motion is set up in the mass of material which creates a condition of energy in the mass suflicient to cancel the frictional resistances between the particles. It should be understood that the character of the required motion for the purpose stated above is continuous in direction and not reversible and further that it is one of small displacements at the highest speeds, therefore, the speed of the motion cycles which are produced in the mass by the apparatus, for the purpose of this invention is of the extra high order, for example, 1000 cycles per minute, or more. y

Different mixtures of materials vary considerably in their physical conditions from various causes, as, for example, the degree of their dryness, which difference affects the ease with which they will stratify under treatment. Some materials respond quickly and easily to treatment, whereas others are slower and more diicult to separate into their components of varying densities.

'I'his invention provides a facile means whereby the particular need in this respect is met. The length of the trough is proportional to the time required for the completion oi' the action, therefore, the length of the trough is made either greater or smaller in accordance with the nature of the material to be treated. Also, in the case of some materials most diiiicult to treat, it is desirable that the treatment should be made in stages or steps. For this purpose a pluralityof troughs may be used arranged in such manner that either or both of the products from the trough used for'the rst stage of treatment is fed on to other trough or troughs for a subseaooario quent stage in treatment, and this method may be repeated any desired number of times.

The kind of motion used has been described above as rotary inform, such as is derived from a truly circular rotation. In special cases it may be advantageous that this motion be varied from a truly circular kind to one which remains rotary but departs from the true circle to some other form such as the ellipse. For this purpose the shape of the cross section of the springs which control the motion according to their deiiecting properties is changed from the circular cross section to one having for example an elliptical cross section. As the major axis of the ellipse of t e spring is directionally the same as the minor axis of the motion ellipse, the desired direction in the case of the latter may be adjusted to any angle which is found to be most effective by adjusting the spring to the corresponding angular position in respect to its sectional form.

In the foregoing description the springs have been stated as being solid bars of particular sectional form. For the purpose of the invention the springs are not necessarily confined to this type, but may be of any alternative form which reacts by the nature of its deflections in the manner described. For example, the springs may be tubular, having an annulus form of section, or constructed in rings formed by bending rectangular bars.

-Experiments have shown that substantial variation of the eifects produced by the described motion is obtained when the direction of rotation is changed, asfrom the clockwise to the anticlockwise. Also by an increase or decrease in the speed of rotation. By combining the eifects so produced it is found that the relative speeds of forward iiow along the trough of the upper and lower layers of the materials in the trough can be made to differ. It has been found possible by so regulating these means that this difference can be made such that the upper layers ilow forwardly in direction when the lower layers move backwardly.

This invention is particularly suitable for the separation of materials whose particles are small in size. In previous processes, for example such' wherein materials iiow along troughs in a stream of water and separation of materials is made according to their densities, because of `the high resistance jointly with the density of the water, it has been found difcult for the finest particles of greater density to fall to the lower layers, whereas in this invention, by the use of air, this resistance may be reduced to a negligible magnitude because of the extreme fluidity of air and its small density.

Mixtures of materials such as coal and stone often contain a material having a density greater than that of coal but less than that of stone. In the treatment of a mixture of this kind, it is sometimes desirable to extract more than two products. This invention includes means whereby a plurality of products are lseparately discharged from the trough. For this purpose, additional openings are provided in the bottom of the trough towards the delivery end, these openings being in the form of narrow rectangular ports arranged parallel to one another at short space intervals. The delivery of any or all of these products may be either returned to the feed, or passed to one or more retreatment troughs, or discharged separately.

In operation, the materials to be separated are fed on to the feed end of the trough by any suitable feeding device or by gravity as is most convenient. Under the actions of motion and air current, the materialsare caused to spread over the surface and by reason of the small inclination of the trough towards the delivery end, they flow forwardly in the form of a gently moving stream which is confined by the upstanding walls. This stream being in a uid state, resembling that of liquids, the heavier particles stratify to the bottom and the materials arrange themselves in strata within the stream in the manner which has been described.

When the materials reach the point where the opening through the bottom of the trough occurs, the heavier particles movingin 'the bottom or near thereto are allowed to pass out of the stream. This discharge is so regulated that only the lower stratum is allowed to pass out in this manner, the material remaining in the stream .being that of a less density, passes over the opening towards the end of the trough and discharges therefrom. The regulation of the discharge of the ybottom layer through the slots in the bottom is preferably made by an arrangement whichconsists of ya U-shaped vessel wherein the fluid condition of .the material l' having passed the slot has a tendency to flow upward in the opposite branch in accordance with the pressure exercised by the material of the first branch. The adjustment of the second branch level will allow a ow only if the equilibrium is disturbed by the input through the slot of heavy material thus establishing ya discharge onlyA if required and regulating automatically the flow speed of the said discharge.

'I'he top layer is not necessarily carried to the end of the trough but one or more cuts can be taken off by means ofv cutters placed adjustably at a convenient depth of the bed across the trough. It has been found that cutters provided for this purpose produce the smallest disturbing action withxegard to the obtained stratification if at the ,same time the layer remaining underneath the cutter is exposed to a drop over a pronounced slope. For this reason the cutters are preferably provided so that their separating edge is placed above a pronounced downward change of level of the bottom of the trough.

The cutting of a top or bottom layer having the effect of lowering the depth of the bed after the cut it can be made use of by means (such as riilles or wedges) having the eifect of narrowing the width of the bed and increasing, therefore, the depth to its former or any other suitable value. 'I'he described narrowing can be obtained as well by a decrease of the width of the trough. Y

It`A has been found that by avoiding the congregation of only fine material in the bottom layer this layer -in stratfying contains heavy material of different size values. In order to take out these ne sizes lling up the interstices between the larger particles and to allow the intrusion of other ne and heavy particles into the said interstices it can be useful to provide at certain points a pervious trough bottom section such that a screening effect is obtained. This screening can be done so that the undersize particles fall into the air chamber underneath the trough -against the air stream. From this chamber Ythe particles can be blown outof the apparatus by suitably provided openings.

For the proper control of the motion suitable means may be provided for varying the speedof rotation of the shaft and the effective length of the supporting springs and for variation of the motion by means for adjusting the unbalanced mass.

Suitable valves or dampers may be placed between the compressor or fan and the air chamber of the trough for the regulation of the air pressure and current. 'Ihe air chamber may be divided into two or more zsections, so that by a specially provided damperit willbe possible to obtain in every section air pressure and quantity as required.

In previous apparatus for similar purpose to that of. this invention where an air pervious surface is 4usedfor supporting the materials being treated and more especially in cases where the materials contain a mixture of sizes, trouble has -been caused by .the small openings of the pervious bottom becoming closed 'by particles of the material falling vinto the openings and becoming lodged therein, thus interfering and upsetting the proper distribution of the air.

In the present invention means are provided for preventing this damaging action. It has been found that by a special arrangement of the area dimension of the openings and the spaces between these, it is possible to provide a condition such that the velocity of the air passing through each individual opening is too high -to permit a' particle of a size to iit the opening to enter therein.

It has been found that in the case of treatment 'of fine material presenting a considerable difference between apparent and true specific gravity, the bed of such material acts like a compressible medium so that the motion is transmitted only over a limited depth of the bed or stream. In order to secure the transmission of the motion through a greater depth perforated plates or grids areV provided so as to form intermediate or false bottoms inside the bed. These intermediate bottoms have to allow the passage downward of any particle that by its nature has to settle on the true bottom and allow thus the passage of the upward directed air current. 'Ihese false bottoms are positively linked up with the trough in order to follow exactly the motion obtained by the action 'of the rotating pulley or pulleys and the springs.

In a similar way riiiles with outstanding edges fastened to the bottom of the trough can be used for the purpose of carrying the motion inside the bed of materials.

The bottom surface of the trough has been described as substantially flat. It should be understood that the invention is not conned to such a form of bottom surface. In some cases it may be of advantage to use a curved or bent surface either convex or concave. The variations of the bottom angles thus obtained can be made advantageous to make use of the differential motion in the bed obtained as previously described. By these means it will be possible to regulate the motion of the bottom layer so as to make it go forward, or backward, or to slow its motion down in either direction comparatively to the motion of the top layer.

In one particular case the angle of the bottom bending towards the slot can be arranged so as to give a definite but comparatively slow motion to the bottom layer, thus steadying the layer whilst the angle of the bottom at the other side of the slot allows a backward movement of the bottom-layer. This arrangement allows to feed the discharge slot in the bottom of the trough from both sides with heavy material flowing in opposite directions and without interference with the flow l'ai ' frame 36 fastened to the walls i.

of the top layer. Also it may be of advantage to have upstanding riiiies on this bottom surface for the purpose oi deiiecting the material; further for the purpose of assisting the discharge ci the stone it may be desirable to provide banking iedges or weirs across the surface near the discharge openings.

In order that the invention may be more clearly appreciated, the accompanying drawings and following description show and describe various ways of carrying the invention into eect by way of example.

In these diagrammatic drawings- Figure I is an elevational View oi' one form of machine according to theinvention.

Figure 2 is a plan view o the machine shown in Figure l.

Figure 3 is an end elevation of the machine .shown in Figure l partly in section and viewed from the line C--D in the direction of the arrow.

Figure e shows an elevation of a cutter for the separation of the top and bottom layers of the material to be separated.

Figure 5 is a plan view of the device according toFigure Figure 6 is a front elevation of the device according to Figure i.

Figure 'l is a sectional view of a Siphon type bottom layer discharging device.

Figures 8, 9, 10 and 11 are sections of the springs used for supporting the trough.

Referring to Figs. 1 through 3 of the drawings, the trough i is provided with two cross members 24 rigidly fastened thereto. Between these cross members are two members 25 which each carry at the inner side a bearing 2t for the shaft 2l, and at the outside a clamping device 2d for the fastening of the bar springs 29. In the centre of the shaft 2l a pulley 3o with the out-of-balance weights 3! is fastened. This pulley is driven by the belt 32 from a motor or other suitable power supply. rlihe springs 2t pass through holes provided in the side walls i and their ends are held in brackets 33 which are fastened to the supporting frame 3i. Thus the trough is supported by the frame 34, the side walls l, the members 24 and 25, the springs 29, and the brackets 33. The bottom of the trough is formed by the pervious metal plate 35 resting on a supporting The air chamber .tl is formed by the space between the plate 38, the trough bottom 35 and the side Walls l. This chamber is subdivided into sections by the upstanding plates 39. Each ysection is connected to a blower 40 by the .ducts 4| provided with' adjustable dampers 42. For discharge purposes the slots 43 are provided across the bottom plate 35. These are connected with the siphon arrangement 44 with an adjustable discharge gate for the control of the discharge of material there through. The intermediate or false bottom 45 is supported by riilies 46.

Figures 4, 5 and 6 show an arrangement of a cutter provided for the separation of top and bottom layers. The cutter 4l divides the bed owing in the direction of the arrow into a top and a bottom layer. This cutter is fastened at hinging points 48 to the upstanding walls of a channel 49. These hinging points are provided with screw clamps (not shown) to allow of adjustment oi' the cutter to suit varying depths or layers. The cutter can be adjusted so as to spill the top layer flowing over it into the channels 50, so that this layer may be carried to the end of the aooai ro trough without being remixed with the layer iowing down over the slope 5l. This lower layer is further treated in the spaces or channels d2 between the channeis 5d. rI'hese channels Si? give the means of narrowing the remaining bed in correspondence to the top iayer so that the depth of the bed may be suitably altered for further treatment. Also, the side walls it of these channels can act as riles. These channels taking the to of a wedge at the end opposed to the advancing material give the means of narrowing the remaining bed while it hows over the slope 5l.

The treatment which taires place in the channels 52 comprises a sifting through a sieve 55, the undersizes from which fall inside the air chamber id, against the air pressure, through the sieve 55, and are blown out of the orifice tti-see FL.,- ures l and 2. K f

Figure 7 shows the arrangement of a bottom layer discharge of the Siphon type and the inclination angle of the pervious bottom plate towards the slot for the said discharge. The main dowing direction of the bed of material is indicated by the arrow.` The angle a is established so that the heavy bottom layer will ow towards the slot 53 with a speed below the average speed of the bed as a result of the differential motion acting on the said bottom layer. In a similar way the angle b is established so as to allow a backward new to the bottom layer. Thus the slot 5t will be fed from two opposed sides. The' material dropping down will meet the resistance of the adjustable gate E'ii so that the room between slot and gate will be lled up and because of the fluid condition of the material obtained by the motion of the trough, a continuously flowing stream will be established whose speed towards the overow over the gate can be controlled by the lower or higher position of the said gate. It is understood that the increase of the pressure in the downgoing branch due to the input of a greater quantity of heavy particles will increase the speed of the ow and conversely the arrival to the slot of less heavy material will decrease the ow velocity. It is apparent therefore that the siphon arrangement shown is self-controlling up to a certain extent for a given adjustment of the gate level.

Figures 8, 9 and 10 show diderent spring sections which can be used for the resilient suspension of the troughs, Figure 8 being a round section giving equal deflections of its end in every direction in a plane vertical to its main axis.

Figure 9 shows an elliptical section giving end deflections of different values in accordance to the axis of the cross section.

Figure 10 shows an ovoid section.

Figure 1l shows a. curved spring bar whose ends or middle portion can deect with rotary or elliptical motion.

I claim: Y

1. In an apparatus for separating a mixture of solid materials having diierent specific-gravities, a vessel for containing said materials, a pair of spring supports for said vessel, a shaft coaxial with said spring supports, a pulley having an eccentric weight thereon mounted on said shaft, and means for rotating said pulley, whereby the axis of oscillation of the vessel is substantially coincident with the axis of rotation of the pulley.

2, Apparatus as claimed in claim l, including means for passing a current of air or gas upwardly through the agitated material.

3. Apparatus as claimed in claim 1, including a pervious trough bottom section, whereby. the bottom layer of the material is screened.

4. Apparatus as claimed in claim 1, including tion of the pulley to the entirel contents of the means for insuring a communication oi.v the mobed of material, comprising perforated plates or tion imparted by the pulley to the entire congrids positively'linked tothe vessel and forming a tents of the bed of material, comprising peri'alse bottom thereof, the said false bottom serv- 5 i'orated plates or grids positively linked to the ing as the sole transmitter of energy to the bed 5 vessel and forming a false bottom thereof. of materials. v v

5. Apparatus as claimed in claim 1, including JOSEPH NICHOLAS S'I'EINME'IZER. means for insuring the communication of the mo- 4

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