US1565236A - Apparatus for sifting fine material - Google Patents

Description

2 Sheets-Sheet 1 G. ROTH APPARATUS FOR SIFTIt G FINE MATERIAL Filed Sept 3, 1921 Dec- 8, 1925- 8, I G. ROTH APPARATUS FOR SIFTING FINE MATERIAL Filed Sept. 5, 1921 2 Sheets-Sheet z Patented Dec. 8, 1925.

UNITED STATES PATENT FFICE.

GEORG ROTH, OF DABMSTADT, GERMANY, ASSIGNOB TO GUSTAV STGCKLE, OF DARMSTADT, GERMANY.

APPARATUS FOR SIF'II'NG FINE MATERIAL.

Application filed September 3, 1921. Serial No. 498,476.

To all whom it may concern.

Be it known that I, Gnone ROTH, a citizen of the German Republic, residing at Darmstadt, Germany, have invented certain new and useful Improvements in Apparatus for Sifting Fine Material (for which I have filed applications in Germany, 1st of Dec. 1919, Patent No. 336,748, Germany 6th of April 1921, Italy, 28th of May 1921, France, 23rd May 1921, Austria, 16th of April 1921, Hungary, 21st of April 1921, Czechoslovakia, 27th of April 1921), of which the following is a. specification.

Separating apparatus for separating fine materials is already known which consists of a plurality of concentric receivers with spreading plates and extending one within the other of which the innermost is formed for the supply of air for separating purposes through a centrifugal fan or blower located at its lower end and at its upper end fits in the annular space formed by two adjacent receivers.

In order to permit of operation of such separating apparatus with air currents blown therethrough and at the same time to obtain the maximum efiiciency in accordance with the invention the separation is effected in several separate currents of which the main blown current strikes the material to be separated at right angles or approximately right angles thereto and a weak current is blown through or several induced currents are drawn through the coarse material already sifted by the centrifugal action and the main current so that any fine material adhering to the coarse material is separated out and led to the main current of air. The additional currents of air may be at an angle to the main current of flow in the same direction. By the repeated treatment of the coarse material a high output of fine ma terial is obtained. It is essential that the material to be separated and the air for separating purposes should be separately supplied in order that the air only should enter the centrifugal blower.

An improvement in the efliciency of the separating is effected by extracting separately therefrom any of the valuable fine material carried by the air current. This separation is effected by intercepting such fine material in the air current returning for commencement of its cycle again. imm di y bef re it ommen es the cycle,

Two embodiments of apparatus suitable for performance of the new method are shown in the drawing in which Fig. 1 is a longitudinal section through one embodiment, Fig. 2 is a longitudinal section through the lower part of a second embodiment. Fig. 3 is a section on the line 11 of Fig. 1, Fig. 4 is a section on the line 2-2 of Fig. 1, and Fig. 5 is a section on the line 3-3 of Fig. 1 the centrifugal blower only being shown.

As shown, the device consists of four concentric cylinders or casings a, b, 0, d of which the innermost a is expanded in the form of a cone at its upper end a and a conical downwardly projecting extension a thereof projects in known manner into the annular space between the receivers o and d. The cylindrical part of the casing a extends towards the rotating suction pipe a Said pipe is carried by a rod 9 rotated by means of a belt pulley h or the like on the end of which is mounted a centrifugal blower e rotating with the tube a and serving to close the same.

The dish shaped blower e is fitted with a flat spreader plate 7 a coarse meshed sieve e surrounding the outlet 0 (see also F 5) and openings 6 in the lower wall. On the outer side of the suction pipe a are mounted in the form of ribs several spreading plates z' which uniformly distribute the material to be sifted which passes through a tube is into the annular space between the receivers a and b and is supplied thereto by the hopper Z. The casing 0 forms with the casings a and b the shifting space proper which tapers downwardly and terminates in a branch m for the outlet of the coarse material.

In the upper part of the receiver 0 are located intercepting plates 12 which prevent the particles thrown upwards or any heavy particles carried upwards by the sifting current from passing over into the space for the fine material between the receivers 0 and cl. The receiver (Z forms the outer wall of the sifting apparatus. It tapers clownwardly to an outlet 0 for the fine material. In the cover of the casing d is located a flap or valve 79 which when desired permits the inlet of auxiliary air in regulatable manner.

In the wall a are provided strips 9 upturned and stamped out from the material inences thereof and beneath the hopper a is provided a receiver w across which extends an inclined wall a closing flap y being provided.

Sitting by means of the sifting apparatus shown in Figs. 1 and 2 is carried out in the following manner.

The material to be sifted entering the inlet 7: passes into the hopper Z thence to the spreading plates 6 which rotate with the suction pipe a and is distributed in this manner uniformly over the whole surface of the spreading plate 7. As the centrifugal blower is so formed that the major portion of the air flows vertically upwards such air strikes the material moving over the spreading plate 7 and throwsit outwards into the annular space A between the receivers (L and Z). The coarse portions which are prevented by the sieve e from entering the blower fall downward beyond the blower and pass in front of the openings 6 of the blower from which a weaker current of air is directed. substantially horizontally which current blows away any fine material adhering to the heavy particles and transfers it to the rising main current of air. The residue freed from fine material passes out at m and is fed to sacks or returned for grinding. The fine material rises upward with the compressed air and thus passes between the intercepting plates 01. These plates are formed with gaps and overlap so that any heavy particles still present are separated out without the air being too greatly obstructed. At the upper part of the cone (1 the air and finematerial are separated, the line material falling largely due to the centrifugal action and passing out through the outlet 0 while the air and a small portion of the line material passes over the cone a into the suction pipe a c and the cycle comagain. Any air passing away through the outlet 0 is replaced by addi tional air entering the sifting apparatus through the valve or flap 7) in the cover of the casing. The valuable tine material carried forward by the returning compressed air into the hopper Z passes in front of the strips 9 and the fine material passes through the openings to behind the same into the re cciver a from which it can be removed by opening the valve or flap g and the doors 2 and in the walls of the receiver 0, (Z. The receiver .1; is made cylindrical so that the sifting space proper A shall be cylindrical throughout.

In the embodiment shown in Fig. 2 the space traversed by the main current of air is divided so as form a small suction chamber B in which the coarse material is freed from any fine material carried therewith and the fine material is transferred from the auxiliary air current into the main air current. On the towel side of the open blower e are arranged bars or strips 6 preferably in line with the blower vanes. Beneath the blower the space A traversed by the main current is closed by a conical base which in the embodiment shown consists of a central dished portion .9 and a conical plate 7" forming an extension thereof but spaced therefrom at o.

On rotation of the blower the bars or strips 2? rotating above the inner surface of the dished portion 3 also exert a blowing action and a. negative pressure is produced in the space E beneath the conical base 8, r. Through the space 4; between the dished portion 8 and the plate 7* there is produced a current of air because the air in consequence of the injector action due to the centrifugal action of the bars or strips 1 is withdrawn from the space B. The coarse material tending to pass to the outlet m is thus subjected in the space A to treatment by three currents of air and passes into the space I) where it is subjected to a further treatment by air under negative pressure which separates any fine material still adhering to the coarse material therefrom and leads it to the main current of air in the space A.

I claim 1. An apparatus for separating fine material comprising in combination a cylindrical casing, a plurality of walls being arranged concentrically to said casing and suitably connected to each other, a suction pipe attached to a central driving axle and arranged. in line with the shortened inner wall and having a disk shaped lower end. a centrifugal blower fixed to the lower end of the central axle near the lower opening of said suction pipe a rotatable member mounted on the lower end of said suction pi )e and. so fitted with a horizontal surface that the material which is supplied to said member will be discharged centrifugazlly from said member when the same rotates. a conical plate connected to the bottom of said blower and being upwardly bentagainst said dish-shaped pipe so as to form a ring shaped outlet for the distributing air current being produced by said blower, and

means for generating an auxiliary horizontal air current adapted to act upon the falling materials and to regain the liner particles from the coarse material falling to the outlet, and means for separating the fine particles from the air currents resuclied by said blower, substantially as set forth.

2. In a separating apparatus in combination with a closed cylindrical casing titted with an outlet a feeding tube of said casing, a plurality of concentric walls supported by said casing and covered by an upper cone -made in one piece with the feeding tube of said casing, a driving axle journalled in the cover of said casing, a suction pipe mounted on said axle, a blower fixed to the lower end of said axle and fitted with an upwardly inclined bottom plate, a distributing member attached to the lower end of said suction pipe and beneath the inner discharging channel said bottom plate having a circle of openings arranged near its upper edge and serving as passages for a Weak horizon tal branch air current acting upon the ma.- terial falling into the discharge opening,

openings provided between the outer wall i and said cone for passing the air and fine particles to the outer channel having an outlet for the fine particles, and openings formed in said cone above a central receiver channel for line particles substantially as set forth.

3. In a separating apparatus in combination with a closed cylindrical casing, a plurality of division-members, an axle journaled within said casing and fitted with means for discharging the materials by centrifugal action, a blower attached to the lower end of said axle and adapted to generate a horizontal air current crossing the discharged material, a conical plate attached to the bottom of said blower and adapted to guide the air current, a shell fastened to the back of said plate by means of interposed strips or blades for forming suction channels for an additional air current, a dished portion attached to the outer wall for restricting the passage for the coarse particles, so that said passage is exposed to the action of a sucking air current, means for separating the fine particles from the rising air current, and means for discharging the line particles, substantially as set forth.

In testimony whereof I affix my signature.

GEO'RG ROTH.

Images