US2986277A

US2986277A - Method and means for treating and sorting comminuted substances

Info

Publication number: US2986277A
Application number: US603697A
Authority: US
Inventors: Ehlermann Helmuth
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-08-13
Filing date: 1956-08-13
Publication date: 1961-05-30
Anticipated expiration: 1978-05-30

Description

May 30, 1961 H. EHLERMANN METHOD AND MEANS FOR TREATING AND SORTING COMMINUTED SUBSTANCES Filed Aug. 15, 1956 2 Sheets-Sheet 1 Invemon- IVE; mu 7'// Ellie-4014M May 30, 1961 H. EHLERMANN METHOD AND MEANS FOR TREATING AND SORTING COMMINUTED SUBSTANCES Filed Aug. 15, 1956 2 Sheets-Sheet 2 United States Patent O METHOD AND lVIEANS FOR TREATING AND SORTING COMlVHNUTED SUBSTANCES Helmuth Ehlermann, Bad Lippspringe, Westphalia, Germany Filed Aug. 13, 1956, Ser. No. 603,697

7 Claims. (Cl. Z09-'133) This invention relates to a process and an apparatus for subjecting finely comminuted particles to physical or chemical treatment and separating them at the same time through a whirling motion.

An object of the present invention is to improve prior art methods and devices of this type and to create a process and an apparatus which can be most effectively applied to a variety of industrial processes.

Other objects of the present invention will become apparent in the course of the following specification.

The subject-matter of the present invention is based on the following consideration:

Particles floating in the air current of a centrifugal separator can be considered as a lattice, so that the air floating therethrough is subjected to a drop in pressure. If the particles are to continue to float, the drop in pressure must be balanced with respect to the total weight of the particles. As far as so-called cyclones are concerned, which are simple layers of gas whirls having a vertical axis, the radius of which diminishes from a maximum to a minimum, particles of small size or weight, such as dust, shavings, etc., are usually sucked by the whirl from their containers and are gathered in a collecting container. This procedure is characterized by the flow of gas and of the particles, such as air or shavings in the same direction.

According to the present invention, it was found that this arrangement can be reversed, namely, the particles can be caused to flow opposite to the direction of flow of the gas, thereby using the faculty of the upward movement of particles in flowing gases. A current of this type, due to its own speed and angular speed, as well as density, can transport a predetermined weight of particles, said weight being dependent upon the size of the particles, the form of their outer surfaces, viscosity and specific weight. If such a gas current is constantly charged by regulated input and output with a larger amount of particles than can be carried away by the current, then these particles will carry out a relative movement within the gas current. For example, in the case of a current which blows spirally verically upward, the particles can be so arranged that they will move spirally vertically downward.

Consequently, the present invention pertains to a process for physically treating comminuted materials and simultaneously sorting them by whirling. According to an embodiment of the inventive idea, a container is provided which may be of cylindrical form, and which contains a massof the treatingsubstance which rises along the side walls of the container and moves downwardly in the middle thereof. To this treating substance is fed the comminuted substance, preferably at the location wherein the upward direction of the current is changed into the downward direction. The amount of the comminuted substance must be such that the settling rate of at least a part of the comminuted substance is greater than the flow speed of the currents. The zone wherein the direction of the current of the treating substance changes from 2,986,277 PatentedMay 30, 1961 cover which is so shaped that the change in directiontakes place smoothly and without interrupting the flow. This cover is designated as a reversing head throughout the specification and the claims, and it is usually ofa'cupola shape.

Thus, according to the invention the particles are moved in opposite direction to the flow of air and their settling rate, therefore, must be greater than the velocity of the counter flowing gas. Then the total weight of the particles is greater than the drop in pressure, which the air is subjected to by flowing through the floating particles. These relationships are valid only if the friction of the side walls of the container is to be discounted. If the friction of the side walls is particularly great, it will increase the turbulency of the air flow, or in thecase of initial laminar flow of the air the flow becomes turbulent, and as the result thereof is already subjected to a drop in pressure; then it is possible to diminish correspondingly the weight of the floating material.

According to an embodiment of the invention, the roughness of the inner surfaces of the side walls is increased. Then the flow becomes turbulent in those portions of the container in which the comminuted material must drop downwardly. In sections which are further removed from the side walls, for example, in the rising portion of the flow, the current will retain its laminar character. The relative movement of the bodies which is attained by roughening the surfaces of the side walls, can be further increased by the insertion of a lattice or the like. T

According to a further improvement of the present invention, the relative movement between thetreating substance and the comminuted substance which is being treated is adjusted depending upon the treatment which is being carried out, so that the comminuted substance remains in the container during a predetermined time period. I

According to a further improvement of the invention, nozzles of blowers are located upon the lower bottom of the cylindrical container close to the central axis thereof, the nozzles being directed tangentially and being used for the injection of the treating substance. The radius of the blow-in circle of these blowers should be approximately one-half of the radius of the circumference of the container.

Furthermore, according to another improvement of the invention, the blower nozzles for the treating substance are arranged in such manner that the outer blown-in mass will lie against the side walls of the container. 2

If the container is not provided with a reversing head upon that end which is located away from the blowers, then a suitable current reversing device can be used with the same eflfect. The reversing head or similar device should be so constructed that the reversal of direction of the mass located adjacent the side walls into a vertical downwardly moving mass takes place without impacts. The bottom of the container has a suction opening which is preferably provided with a curved filling body so as to attain high suction speeds. The radius ofthis suction opening is preferably about 40% of the radius of the outer circumference of the container.

As already stated, the inner surfaces of the side walls are roughened or provided with a lattice to increase turbulency of flow to the outer portion of the mass.

According to another feature of the invention, a separator is connected with the suction opening of the container and is located behind the opening, whereby the exhaust gases are passed through twisting blades and their particles by centrifugal forces, while the twistingblades greatly increase the circumferential velocity of the gases.

projects upwardly close to the abovementioned distributor.

The bottom of the container may be raised at its outer portions to form a flange extending to the side walls,

so that the material being treated may be withdrawn into a slot between the flange and the outer wall of the casing. The suction opening may be provided with a suction pipe,

the distance of the upper end of which to the bottom .should be about one-half of the radius of the container.

The distance of the nozzles of the blowers to the bottom should be about 0.4 of the radius of the container. When i the above proportions are maintained, a completely predominant part of the treating substance blown through the nozzles will rise within the container.

Furthermore, according to the invention, it is possible to operate with pressure blowers as well as suction blowers. The suction blowers can suck in more of the treating substance than is supplied through the nozzles of the pressure blowers, and then the diiference can be supplied from another location to the container, for example, through openings provided at the bottom. The blowers can be located closer to the suction tube than to the flange.

The invention will appear more clearly from the following description when taken in connection with the accompanying drawings showing, by way of example, a

preferred embodiment of the inventive idea.

In the drawings:

Figure l is a diagrammatic longitudinal section through an apparatus constructed in accordance with the principles of the present invention and used, for example, for the treatment of iron ore.

Figure 2 is a transverse section along the line IIII of Figure 1.

Figure 3 is a transverse section along the line III-III of Figure 1.

Figure 4 shows a portion of the container partly in side view and partly in section and illustrates diagrammatically the sifting procedure in the reversing head.

The apparatus shown in the drawing includes a conical container 1. Obviously the container may be cylindrical or may have any other suitable form. The upper end of the container is closed by the reversing head 2, constituting its cover. The reversing head 2 must be so constructed that the direction of the flow can be changed to the extent of about 180 with as little impact as possible. The container is provided with a bottom 3 carrying curved supports 4 upon which the blowers 5 are mounted. As shown in Figure 2, the axes of the blowers 5 extend tangentially upon a circle and around the vertical axis of the container 1. The blowers are supplied with a treating substance by a suitable blowing apparatus which is not shown, through an annular channel 5a provided in the lower portion of the container, and pipe 5b. Due to this arrangement a rotary fiow is provided in the entire space between the walls of the container 1 and a suction sleeve. The bottom 3 has a suction opening in the middle which is enclosed by the suction sleeve 6. The device is to be so operated that the entire space between the upper walls of the container 1 and the suction sleeve 6 is filled with a gaseous flow. Since due to the centrifugal force the gases will have the tendency to move toward the outer walls of the container 1, the blowers 5 should not be arranged in the middle between the outer side walls of the containerl and the suction sleeve 6, but should be placed somewhat closer to the suction sleeve 6 so as to avoid empty spaces.

.The suction opening, which is located' in thebottom 3, is. used for the separation of dust in that the exhaust .sa u ast de h ou h iw st nglbladesfia (Fig. 2) and it direction is sharply turned, whereupon it is removed through an exhaust pipe 8, shown in Figures 1 and 3. A suitable suction device (not shown) is connected to the pipe 8. The distance of the upper edge of the suction sleeve 6 from the bottom 3 is of substantial importance. If this distance is too small the current will flow to a large extent directly through suction sleeve 6. On the other hand, if the distance is sufficiently great the current is forced to rise within the container 1. These considerations presume a predetermined height of the axis of the blowers 5 above the bottom 3.

To create the desired flow it is advantageous to use independently operating flowing devices operating through the pipe 5b and suction devices operating through the pipe 8. By way of example, it is possible to suck in more gas than is introduced through the pressure blowers. Then the difference in the amount of gas can be introduced into the container, through suitable openings 11:, shown in Figure 2, which are provided in the container 1 at the level of the blowers 5. The blowers 5 (Fig. 1) may be located closer to the suction sleeve 6 than to the flange 17. If the substance being treated is supplied close to the outer wall of the container 1, it is supplied (looking in the vertical direction) near the blowers through the pipes So which are connected to a common pneumatic feeder circuit for the substance to be treated (not shown). Obviously, if a special treating gas is used, the openings 1a must be connected to the gas conduits (not shown). Otherwise air is introduced through the openings in.

The suction opening of the suction sleeve 6 is advantageously provided with a curved filling body 9, so as to create the highest possible suction speed due to the narrow cross-sectional area. A cyclon or separator 23 having a base 10 is located below the suction sleeve 6, and is suspended from the bottom 3 of the container 1. The separator 23 which is indicated only diagrammatically in Figure 1, operates in a manner well known in the art, namely, it has a high angular velocity, so that solid particles will be ejected. Since the current flow is bent radically at 7 (Fig. l), the particles ejected upon the inner wall of the sleeve 6 above 7, as well as the mass 24 (particles or liquid), are collected in the container 10, from which they are removed by any suitable means.

In the example illustrated, a funnel 11 for the comminuted material is mounted upon the reversing head 2. A distributor 12 is located below the funnel 11; it may remain stationary or be rotated if desired. The rotation of the distributor 12 is advisable when a short circuit is observed, namely, for example, when the entire ore flows toward the suction sleeve 6 without being drawn to the outer walls of the container 1. To assure the desired operation, the ore can be introduced through openings in the bottom of the container 1 close to the blowers 5. For that purpose the pipes 50 are provided, so that the ore may be immediately carried toward the reversing head 2.

The operation is as follows:

The directions of the flow are indicated in the drawings. The treating substance introduced under pressure through the nozzles 5 rises spirally upwardly from the bottom 3 and may be observed as a current (a boundary of which is designated by 13) rising upwardly along the side walls of the container 1, as well as an inner upwardly rising current (a boundary of which is designated by 14). The current 13 follows the side walls of the container 1 toward the reversing head 2. The current 14 gradually moves closer toward the side walls of the container 1 so that both currents flow throughout the zone of the reversing head 2 from the side walls towards the interior. The currents have the same horizontal velocity throughout the entire cross-section, but different vertical velocities in axial section from outer boundaries toward the interior. There is no vortex action. Then the entire gas moves down- .wardlythrough the. middle of the container in the form of. currents 15 and is removed through-the suction sleeve 6 and the exhaust pipe 8.

takes place somewhat above the blowers 5.

The apparatus is charged with the material to be treated through the funnel \11. This material can consist, for example, of comminuted ore, the size of the particles being about 50 micron. The comminuted substance forms a circular vertical whirl 16, which also rotates around the central axis of the container 1. Practical experience has shown, that this comminuted material will be carried uninterruptedly in fine or less fine swarms under the reversing head 2 so long as it is maintained floating by the upward forces of the

currents

13 and 14. If the supply of the material to be treated continues to increase, these swarms will slowly sink along the side walls of the container 1 while carrying out a spiral rotary movement. The feed particles follow the path 16 automatically after being thrown into the path of the

streams

15, 14 and 13 (Fig. 4). The speed of rotation of the distributor 12 must be limited depending upon the type of coarse par- :ticles and other factors.

The bottom 3 is provided with a flange 17 which is spaced from the side walls of the container 1.

The major portion of the comminuted material can be then removed through the spaces formed between the side walls of the container 1 and the flange 17, and will drop through openings formed in the bottom 3 into channels 18 located under the bottom 3. The channels 18 may contain a transporting band (not shown) for the removal of the treated material.

However, the lightest particles of the comminuted material will follow the current 15, as will be described in detail hereinafter.

Thus, the major heavier part of the material being treated is guided downwardly in the form of a spirally rotating current 19, which is directed axially downwards, while the

gas currents

13, 14 also rotate spirally, but move vertically upward in the axial direction of the easing. Thus, when projected upon a surface extending through the axis, the directions of the gas and of the substance being treated will appear to be in precisely opposite directions. Therefore, in this case the substance being treated does not merely drop as a result of its weight, but its speed is entirely dependent upon the amount of gas which isintroduced and its characteristics, particularly its speed and angular speed, as well as density.

It was also found that the described apparatus has at the same time the characteristics of a separator. Larger particles of the material being treated do not participate namely in the whirling current 16, but are directly removed from the distributor 12 and formed into the central downwardly flowing current 20. As shown in Figure 1, the current 20 passes through the suction sleeve 6, so that the larger particles can be collected in the container located below the suction sleeve 6. On the other hand, the finest particles of the material being treated while following the current 16, will also follow the axial gas current and are sucked through the opening 8 along with the gas current. This procedure is illustrated diagrammatically in Figure 4, which illustrates the path of particles of various sizes.

The behavior of the different grain fractions as set forth above may be described as follows:

The largest grain particles (above 60 microns) are of such weight that they are not carried along with the whirling current 16 up to its meeting point with the ascending

gas currents

13 and 14, but are caught immediately by the descending current and separated in the container 10. The particles of medium size (between and 60 microns) follow, depending on their lower weight per grain unit, the current 16 up to the above named meeting points with the

currents

13 and 14. The finest particles (below 40 microns) with the lowest weight A per grain unit will not only follow the current 16 up to the meeting points with the

currents

13 and 14 but will be transported along the inner surface of the reversing head 2 until they enter the downwardly directed current 20. These small particles cannot be separated even in the cyclon or separator 23, and therefore they escape through the exhaust pipe 8 together with the exhaust gases. This behaviour of the diflerent grain-fractions corresponds to the well-known physical law according to which the rate of vertical descent of a grain in a gas under the influence of gravity is proportional to its diameter. The rate of vertical descent of the largest grain particles is too great to enable them to follow the ascending current up to the meeting point between current 16 and

currents

13 and 14. On the other hand, the rate of vertical descent of the smallest particles is so low that these particles-will not descend at the meeting point between

currents

16 and 13 together with the latter current. Consequently, in the process according to the invention, the influence of gravity is superposed by the influence of centrifugal forces which urge the fine and the medium size grains close to the wall of the container 1 and the reversing head 2.

The described grain particles refer to iron ore or to any other substance having the same specific weight.

It was also found that the pressure of the blowers can be comparatively small, namely, about 300 mm. when the container has a height of 5 meters.

It is apparent that the described process can be adapted for other suitable purposes, namely, the substance to be treated can also be a liquid provided it is suitably distributed by the distributor 12. Practical experience has shown that of utmost importance in the carrying out of the process is the inter-relationship of all the factors involved, since only then the substance being treated can be maintained in the current 19 for a time period which is required for a specific treatment.

It is also possible to connect in series a plurality of the described apparatus.

What is claimed is:

1. An apparatus for treating and sorting comminuted and dispersed substances, said apparatus comprising a vertical container having a round bottom, side walls, a flange extending between said bottom and said walls, a space being formed between said flange and said side walls for a comminuted substance, and'a cover consisting of a curved reversing head located opposite said bottom for gradually reversing upward currents of a treating substance within said container, a plurality of blowers for introducing said treating substance, said blowers being mounted upon said bottom in a circle around the central axis of said container and extending trangentially to said circle, a charging device carried by Said reversing head, a distributor carried by said reversing head below said charging device, said bottom having a central draining opening formed therein, a curved body within said opening, a sleeve extending upwardly from said bottom and enclosing said opening and said body, and a cyclone separator located below said opening and having twisting blades for turning the direction of flow of exhaust gases.

2. The apparatus for treating and simultaneously windsorting a comminuted substance by a gaseous substance, which comprises a substantially round container having side walls, a round bottom and a cover consisting of a curved reversing head and carried by said side walls, a charging device carried by said reversing head for introducing said comminuted substance, a plurality of blowers for introducing said gaseous substance, said blowers being located upon said bottom and forming a blow-in circle the radius of which is substantially equal to one half of the radius of said round bottom, said blowers extending tangentially to said circle, said bottom having a central suction opening formed therein for the withdrawal of said gaseous substance, and a flange carried by said bottom sorting a comminuted substance by a gaseous substance, which comprises a substantially round container having side walls, a round bottom and a cover consisting of a curved reversing head and carried by said side walls, a

charging device carried by said reversing head for introducing said comminuted substance, said bottom having a central suction opening formed therein for the withdrawalof said gaseous substance, a curved filling body in said opening, the radius of said opening being substantially 40% of the radius ofsaid bottom, a plurality of blowers for introducing said gaseous substance, said blowers being located upon said bottom and forming a blow-in circle the radius of which is substantially equal to one half of the radius of said round bottom, said blowers extending tangentially to said circle, a flange carried by said bottom adjacent to and spaced from said side walls for receiving said comminuted substance, and a cyclone separator connected to said bottom and located below said opening.

4. The apparatus according to claim 3, wherein said side walls have rough inner surfaces to increase the turbulency of the flow.

5. The apparatus for treating and simultaneously windsorting a comminuted substance by a gaseous substance, which comprises a substantially round container having side walls, a round bottom and a cover consisting of a curved reversing head and carried by said side walls, a charging device carried by said reversing head for introducing said comminuted substance, a distributor carried by said charging device, said bottom having a central suction opening formed therein for the withdrawal of said gaseous substance, a sleeve enclosing said opening and projecting upwardly from said bottom, the distance of the upper edge of said sleeve from said bottom being substantially one half of the radius of said bottom, supports carried by said bottom, blowers carried by said supports for introducing said gaseous substance, said blowers being located around said sleeve at a distance from said bottom which is substantially 0.4 of said radius,

and a projecting flange carried by said bottom adjacent to and spaced from said side walls for receiving said comminuted substance in the space between said flange and said. side walls, and channels located below said bottom and communicating with said space, said bottom having other openings formed therein and communicating with the interior of said container.

'8 substance containing relatively fine, intermediate and coarse particles, regulating the amount of the charge of said comminuted substance so that at least a portion thereof has av settling rate which is greater than the velocity of. the counter flowing gaseous substance to provide a settling of said portion during a predetermined time period, whereby said fine particles are subjected to a whirling action by said currents in said region, said intermediate particles are conveyed to said outer upwardly moving currents through which they descend, and said coarse particles descend along with said inner downwardly moving currrents, separately removing said coarse particles along with the fine particles and separately removing said intermediate particles.

7. The process of treating and simultaneously windsorting a comminuted substance, which comprises continuously blowing said gaseous substance and forming it into outer upwardly moving currents, reversing the direction of said upwardly moving currents at a predetermined region and forming inner downwardly moving currents constituting continuations of said outer upwardly moving currents, continuously sucking-in said inner downgaseous substance, adding to said currents an amount of gas equal to the difference between said rate of blowing and said rate of sucking-in, charging said gaseous substance at said region wherein said outer upwardly moving currents change into said inner downwardly moving currents with a comminuted substance containing relatively fine, intermediate and coarse particles, regulating the amount of the charge of said comminuted substance so that at least a portion thereof has a settling rate which is greater than the velocity of the counter flowing gaseous substance to provide a settling of said portion during a predetermined time period, whereby said fine particles are subjected to a whirling action by said currents in said region, said intermediate particles are conveyed to said outer upwardly moving currents through which they descend, and said coarse particles descend along with said inner downwardly moving currents, separately removing said coarse particles along with the fine particles and separately removing said intermediate particles.

References Cited in the file of this patent UNITED STATES PATENTS