RU2299874C1 - Bead-type two-rotor grinder - Google Patents

Abstract

FIELD: equipment for grinding of solid mineral and organic substances in liquid medium.

SUBSTANCE: bead-type two-rotor grinder has milling chamber with cooling jacket within which are mounted two free-ended rotors with paired disks fixed on rotor shafts and one disk in their upper position on one shaft and in their lower position on other shaft, individual drive for each rotor, suspension inlet unit and suspension drain units. Each rotor has shaft and bushing secured with shaft through loose tongue joint and designed for transmitting of torque from drive. Suspension inlet unit is positioned in lower part of milling chamber and comprises grid with pulping device arranged at milling chamber inlet end. Suspension drain unit is arranged in upper part of milling chamber outside grinding zone and comprises readily detachable slit-type cartridge filter joined to viewing lantern positioned outside milling chamber.

EFFECT: improved safety in carrying out of grinding procedure, in particular, in grinding of explosive substances.

2 cl, 4 dwg

Description

The double-rotor bead grinder is designed for fine and ultrafine grinding of solid mineral and organic materials in a liquid medium, i.e. in the form of suspensions. The specified grinder can also be used to grind crystalline explosives, such as ammonium perchlorate, to particle sizes of 2 microns or less.

In industry, vertical single-rotor shredders are most widely used. A known method of using a single-rotor vertical grinder for grinding ammonium perchlorate RU 2247101 C2, C06B 21/00, B02C 17/16. There is information about mills with two or more rotors (Belgian patent No. 78454, k01F, filed June 7, 72).

In the journal "Chemical and Petroleum Engineering" No. 12 for 1983, on pages 17 and 18, an article was published by the authors G.S. Posysoev, A.A. Efenin, F.I. Lyashko, P.F. Valuisky "Beaded two-rotor grinder" , which describes the design of the developed bead two-rotor grinder and adopted by the authors as a prototype. The advantage of two-rotor grinders is their higher technical and economic indicators. It should be noted that explosives are sensitive to mechanical stress. Under certain mechanical influences, tanning centers can occur with a transition to rapidly spreading processes of volumetric combustion or explosion. In this regard, in relation to the grinding of explosives, a number of structural elements of the above grinder should be finalized or modified taking into account the following disadvantages of the prototype.

In the prototype, the suspension is introduced into the grinding chamber through a ball valve. When using a bead two-rotor grinder with the specified valve, there have been cases of clogging. These cases were associated with the fact that a suspension of finely dispersed ammonium perchlorate is prone to structure formation, leading to inconsistency of the suspension properties in terms of rheological characteristics. For this reason, the non-uniform and pulsating nature of the suspension flow through the ball valve occurred. A gradual accumulation of ammonium perchlorate agglomerates in front of the ball valve was noted, followed by clogging of the supply pipe.

In the prototype, a frame with a mesh having slotted openings and serving to separate the grinding media from the suspension is installed above the grinding chamber. During the operation of the grinder, an intensive movement of the suspension occurs, as a result of which its upper level constantly fluctuates. Moreover, on the surface of the grid at the interface between it and the upper level of the suspension, crust formation occurs with a constant increase during prolonged operation. At the same time, there is a gradual rise in the level of the suspension until overflow over the edge of the grid, which is unacceptable, because will lead to the bead entering the finished product. To clean the mesh requires stopping the grinding process, opening the casing, removing the mesh and cleaning it. When working with fire and explosive products, these operations are unsafe. This phenomenon is accelerated by the use of volatile liquid media in suspension.

In the bead two-rotor grinder, adopted for the prototype, the disks with the rotor shaft are fastened with prismatic inserts, which does not exclude the play of both disks and liners relative to the shaft. In this case, the impact may occur due to shock and friction on the product, which is also unsafe when working with explosives. In addition, when working with a suspension of explosives using volatile liquids, it is of particular importance to ensure the density of contact of the rotors with the chamber. At the same time, the state of the seal assembly should be monitored.

An object of the invention is the introduction of a number of design improvements in a bead two-rotor grinder to ensure safe process conditions when grinding explosives.

The technical result of a constructive improvement of a bead two-rotor mill, including a grinding chamber with a cooling jacket, inside of which two rotors are mounted cantilever with paired disks placed on their shafts and one disk in the upper position on one and in the lower position on the other shaft, an individual drive for each rotor, the nodes of the input and discharge of the suspension is achieved due to the fact that the rotors consist of a shaft and a sleeve fastened to it with a key connection to transmit torque from the drives, the disks on the shaft are fastened using spacer sleeves with a tongue-and-groove connection, the suspension input unit is located in the lower part of the grinding chamber and includes a grating with a wiper at the entrance to the grinding chamber in the form of a sleeve with a socket on which polyurethane plate scrapers are placed crosswise, and the sleeve is placed with the possibility of its axial movement, the scrapers are pressed against the grate by a calibrated spring located on the sleeve with the restriction of its axial movement by the amount of allowable wear of the scrapers, while intermittent rotation of the sleeve in a cycle by an angle of at least 90 ° with a return to its original position is carried out by a pneumatic cylinder through a lever transmission, and the suspension discharge unit is installed in the upper part of the grinding chamber outside the grinding zone and includes an easily removable slot filter cartridge, docked with an inspection lamp located outside the grinding cameras.

Each of the rotors at the entrance to the grinding chamber is sealed with two spaced apart cuffs, the gap between which is communicated with the inspection lamp.

The bead two-rotor grinder according to the invention is shown in figure 1. It consists of a grinding chamber 1 with a cooling jacket, two drives 2 with V-belt drives. Two rotors 3 are mounted cantileverly inside the grinding chamber. In the upper part of the grinding chamber, a suspension unit 4 is placed, and in the bottom part, a suspension input unit 5.

One of the rotors in assembled form is shown in figure 2. It consists of a shaft 6 and paired disks 7, of which the upper is made integral, and the lower with holes. In addition, on each shaft, one disk 8 is installed in the upper position on one shaft and in the lower extreme position on the other. The rotor is rotated through a sleeve 9 mounted on the rotor shaft at the key 10. The disks are fastened to the shaft using spacer sleeves 9, 11, 12, 13 with end spikes included in the grooves of the disks. The discs are tightened on the shaft with nut 14. The rotor at the entrance to the grinding chamber is sealed with two spaced apart cuffs 15, the gap between which is communicated with the inspection lamp 16 for visual inspection of the integrity of the seal.

The suspension discharge unit shown in FIG. 3, which simultaneously performs the task of separating the beads, includes a cartridge slit filter that is coupled to the viewing lamp 18 of transparent material. The suspension discharge unit is installed in the nozzle of the grinding chamber and fixed in it with hinged bolts 19. Fastening with hinged bolts allows, if necessary, to quickly replace the filter.

The suspension input unit is shown in FIG. 4. An adapter 20 is installed at the bottom of the grinding chamber 20 with a grill 21 and an O-ring seal of joint 22. In a cup 23, fastened with an adapter with a flange connection, a sleeve 24 is placed, on the socket of which polyurethane plate scrapers 25 are crosswise inserted into special slots. Cleaning the lattice with scrapers when exposed to them the force of the calibrated spring 26 is produced by continuous rotation of the sleeve at an angle of at least 90 ° with the return of the pneumatic cylinder 27 to its original position through the lever transmission. The lever 28 on the sleeve 24 is fixed with a collet clamp 29 with the possibility of its axial movement by an acceptable value δ of wear of the scrapers. Sealing the input of the suspension and the safety of its operation is ensured by the installation of cuffs 30, fluoroplastic sleeves 31, 32 and ring 33.

Grinding on a bead two-rotor grinder is as follows. Up to half its volume, beads with a diameter of 1.6-2.0 mm from high-strength glass are loaded into the grinding chamber through the hatch in the lid to half its volume. Turn on the rotor drive in series. The pump through the input node into the grinding chamber of a bead two-rotor grinder serves a suspension with the content of the crushed explosive from 15 to 30% in a volatile liquid medium. Intensive grinding of explosives occurs due to impact and friction of the beads in the grinding chamber. The suspension with the crushed particles, passing the slotted cartridge filter, is poured by gravity into the receiving tank, from which it is again fed to the mill by the pump. The circulation of the suspension of the explosive through the grinding chamber of the bead two-rotor grinder is continued until a given particle size is obtained. The grinding process is carried out with continuous operation of the device for wiping before entering the suspension through the grate into the grinding chamber. During the functioning of the wiping device, the agglomerates and the structure of the suspension are destroyed, giving it a mobile state, which ensures stable continuous operation of the bead two-rotor grinder during the grinding of the explosive.

The double-rotor bead shredder with the distinctive features described above was tested with positive results at the experimental chemical plant of the Federal State Unitary Enterprise "Research Institute of Polymer Materials".

Claims (2)

1. Bead two-rotor grinder, including a grinding chamber with a cooling jacket, inside of which two rotors are mounted cantilever with paired disks placed on their shafts and one disk in the upper position on one and in the lower position on the other shaft, an individual drive for each rotor, nodes input and discharge of the suspension, characterized in that the rotors consist of a shaft and a sleeve fastened with a key coupling for transmitting torque from the drive, the disks on the shaft are fastened using spacer sleeves with a spike connection h, the suspension input unit is located in the lower part of the grinding chamber and includes a grating with a wiper at the entrance to the grinding chamber in the form of a sleeve with a bell, on which polyurethane plate scrapers are placed crosswise, the sleeve being placed with the possibility of its axial movement, the scrapers are pressed against the calibrated grate a spring located on the sleeve with a limitation of its axial movement by the value of the allowable wear of the scrapers, while the continuous rotation of the sleeve in a cycle by an angle of at least 90 ° with a return to the original the position is carried out by a pneumatic cylinder through a linkage, and the suspension discharge unit is installed in the upper part of the grinding chamber outside the grinding zone and includes an easily removable slotted cartridge filter docked with a viewing lamp located outside the grinding chamber. 2. The bead two-rotor grinder according to claim 1, characterized in that each of the rotors at the entrance to the grinding chamber is sealed with two spaced apart cuffs, the gap between which is connected to the inspection lamp.

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