RU2389555C1 - Lab's bead mill - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to equipment intended for milling solid materials. Proposed lab's bead mill comprising milling container with cooling jacket, rotor with disks and rotor drive. Milling container with cooling jacket is mounted aligned with rotor on cup-like pan rigidly jointed to pneumatic cylinder rod. Said pan presses milling container against the cover. Pickup is mounted at the level of milling container.

EFFECT: expanded operating performances.

2 dwg

Description

The invention relates to the field of grinding of solid materials and can be used for ultrafine grinding of solid materials, including explosives in laboratory conditions. To increase the efficiency of mixed solid rocket fuels (STRT), the use of ammonium perchlorate with a mass-average particle size (SMRCH) of 0.5-1.0 μm is required. At the stage of development of STRT compositions, laboratory equipment is needed to ensure the production of ammonium perchlorate with the indicated particle sizes with a relatively short grinding time.

Known for the widespread use of high-speed dispersants (bead mills) for processing pigments (P.I. Yermilov Dispersing pigments. M: Chemistry, 1971). Known analogues: a bead two-rotor grinder - patent RU 2299874, IPC С06В 21/00, В02С 17/16 and a laboratory mill for fine grinding of materials - patent RU 2206399, IPC В02С 15/16. However, the bead twin rotor mill is designed for industrial use. The disadvantage of a laboratory mill is its lack of effectiveness, as it is intended to increase the fineness of grinding from 0.25 mm to 0.08 mm.

In the manufacture of an ultrafine fraction of ammonium perchlorate in industrial production, bead mills are also used - patents RU 2246472, C1 MPK С06В 21/00, 29/22, 45/30, С06D 5/00, RU 2247101, C2 MPK С06В 21/00, В02C 17 /16.

The catalog “Grinding equipment”, TsINTIHIMNEFTEMASH, Moscow, 1976 contains information on mass-produced bead mills with a grinding container volume from 5 to 125 l.

The types of bead mills listed in the catalog are intended for operation according to the scheme with continuous feeding of the suspension from below by a pump and gravity withdrawal from the upper zone of the container. In practice, there is a need to refine the parameters for grinding new materials in low-volume model laboratory mills of periodic action, that is, loading in the volume of the grinding container. Close in volume of the grinding container, laboratory apparatuses include the MBS 5KV2 bead mill, which is adopted as a prototype from the catalog “Grinding Equipment”, TsINTIHIMNEFTEMASH, Moscow, 1976, pp. 5-7.

The prototype - the MBS 5 KV2 bead mill consists of a grinding container with an electric wire, a pumping station driven by a motor-variator. The grinding container is a vertical cylindrical vessel with a jacket for cooling, inside of which there is a shaft - rotor with disks mounted on it. All components and assemblies are mounted on a bed. Grinding is carried out according to the following scheme: the initial product in the form of a suspension from the hopper through the inlet valve and the lower hole in the bottom of the grinding container is pumped. Pre-grinding container is filled with grinding media - glass balls. When the rotor rotates, the particles of material during the passage of the suspension from bottom to top of the grinding container are crushed as a result of friction and impact of grinding media. Next, the suspension by gravity leaves the container. The degree of grinding is controlled due to the residence time of the suspension in the container, namely by changing the performance of the suspension supply by the pump. However, the use of the MBS 5KV2 bead mill is acceptable mainly when producing products in small batches according to the established regimes. Using it to refine the grinding parameters of new materials on a laboratory scale has certain disadvantages:

1. It requires a lot of test material, since a grinding scheme with a flow of a significant amount of suspension through a grinding container is provided.

2. The use of this mill in a laboratory version with a single loading into a container is complicated by the fact that there is a need for multiple disassembly and assembly of the container associated with unloading the suspension with beads, separating it from the suspension, washing and drying both the container and the beads.

3. Multiple assembly and disassembly of the mill is associated with the performance of mechanical work, which is unsafe when working with explosives due to their sensitivity to mechanical stress: friction and impact.

The technical task is to create an effective laboratory bead mill for ultrafine grinding and safe in operation design.

The technical result consists in the fact that the laboratory bead mill contains a grinding container with a cooling jacket and a lid, a rotor with disks, a rotor rotation drive, the grinding container with a cooling jacket mounted coaxially to the rotor on a bowl-shaped tray rigidly connected to the rod of the pneumatic cylinder, which compresses the grinding container to a lid, and a sensor is mounted at the level of the grinding container.

Figure 1 shows a General view of a laboratory bead mill.

Laboratory bead mill includes:

1) grinding container,

2) a cooling jacket,

3) rotor

4) wheels

5) rotor rotation drive,

6) pneumatic cylinder

7) rack

8) a bowl-shaped pallet,

9) stock

10) cover;

11) sensor.

Work on a laboratory bead mill is as follows. A grinding container 1 with a cooling jacket 2 is installed on a bowl-shaped pan 8. By supplying compressed air to the pneumatic cylinder 6 by means of a rod 9, the grinding container 1 with a cooling jacket 2 is pressed against the lid 10. In this case, the sensor 11 gives a signal that the grinding container 1 is pressed against the lid. Through a hole in the lid 10 load a predetermined number of glass beads (beads) with a diameter of 1.6-2.0 mm Then through the same hole load pre-prepared sample of a suspension of crushed material. Turn on the supply of cooling water to the cooling jacket 2. Turn on the drive 5, the rotation of which is transmitted through the V-belt drive to the rotor 3 with the disks 4. The rotation of the disks 4 results in intensive movement of the glass balls. Particles of the crushed material, falling between the glass balls, are subjected to shock and friction, due to this, grinding occurs. When grinding explosives, the process is carried out remotely. After the specified grinding time has passed, the rotor 5 rotation drive is turned off, the cooling water supply to the jacket 2 of the container 1 is turned off. The compressed air supply is switched through the upper fitting of the pneumatic cylinder 6, the grinding container 1 with the cooling jacket 2 is lowered to the lower position. The grinding container 1 with the cooling jacket 2 is removed from the bowl-shaped pan 8 and the contents of the grinding container are poured onto a sieve mounted on a receiving vessel. In this case, the separation of the beads from the suspension.

The advantage of this mill is the ease of connecting and disconnecting the jacketed container to the lid. The presence of a sensor signaling that the container with the jacket is pressed against the lid and its blocking with the drive allows avoiding premature shutdown of the drive and lowering of the container with the jacket while the drive is running, since premature switching on of the drive before pressing the container with the jacket to the cover and lowering it before turning off the drive to the release of beads with a suspension from the mill. The sealing used in the application by pressing the container to the lid is especially necessary when working with explosives, since manual operations with connecting elements are excluded.

The mass average particle size of the material being ground depends on the duration of grinding.

Figure 2 shows, as an example, the dependence of the mass-average particle size (SMRP) of ammonium perchlorate on the duration of grinding in a laboratory bead mill. From figure 2 it follows that at the laboratory bead mill the task is achieved, namely, the mass-average particle size of ammonium perchlorate is obtained at the level of 0.65 μm for a relatively short grinding time of 8 hours.

The data are obtained in the conditions of the experimental chemical plant of FSUE NIIPM.

Claims (1)

A laboratory bead mill containing a grinding container with a cooling jacket, a cover, a rotor with disks, a rotor rotation drive, characterized in that the grinding container with a cooling jacket is mounted coaxially with the rotor on a bowl-shaped tray rigidly connected to the rod of the pneumatic cylinder, which presses the grinding container against the cover, and a sensor is mounted at the level of the grinding container.

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