SU1080854A1 - Centrifugal mill - Google Patents

Abstract

A CENTRIFUGAL MILL, containing a multistage body, with a rotor in it in the form of a vertex S i -; .-; five ..- ; Ma) I; ..;: .. jrt .- “A ticking shaft carrying disks with gift elements, the diameter of which increases in steps in the course of movement of the ground material from top to bottom, a downpipe, loading and unloading nozzles and located on the end of the rotor from the side the bottom disk is a working cola, with a fan, characterized in that, with the purpose of performance behavior, uniformity of the fractional composition of the finished product, reduction of specific energy consumption and wear of the impact elements, the rotor shaft from the bottom disk side is made from prices eral opening and with radial windows located at the level I interdisk spaces. (L

Description

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The invention relates to a mill for the production of various highly dispersed materials and can be used in the mining industry, the production of pigments, and powder metallurgy. A multistage centrifugal mill is known, comprising a casing with loading and unloading devices and a stepped rotor having discs with a hub on which blows and blades are rigidly fixed, creating a ventilation effect, as well as overflow holes made close to the hub, connecting the working space between discs of individual steps. When the mill operates between the discs, a centrifugal countercurrent classification zone is formed, in which large particles due to the prevailing action of centrifugal forces; move to the periphery of the disk, fall under the hammer and break down, and small, no longer requiring grinding particles The skewers mounted on the log-on disks are moving towards the hub and through the overflow holes are carried to the next stage without grinding 1. The disadvantage of the design of the mill is low The operation of the blades is relatively small in the interdisk space and designed to push the air towards the center of the stage, which in principle excludes the possibility of efficient operation. Because of this, the efficiency of the intra-centrifugal counter-current classification is very low. In addition, small particles are not removed from the mill immediately, but are transferred to the next stage through overflow holes, which, with a low classification efficiency, does not exclude their repeated destruction, i.e. remelting, increased specific energy consumption and reducing the degree of uniformity of the finished product. Closest to the invention in its technical essence and the effect achieved is a centrifugal mill comprising a multistage housing, a rotor in its form in the form of a vertical shaft carrying discs with impact elements, the diameter of which increases gradually from top to bottom along the movement of the ground material from top to bottom. , loading and unloading nozzles and impeller located on the torus of the rotor from the bottom side of the fan. In this mill, the grinding efficiency is increased due to the fact that the fine particles through the overflow pipes are withdrawn immediately after the last stage and are not regrind, and the coarse particles that are not crushed in the last stage return to the previous stage 2. The disadvantages of the known design are the low efficiency of the interstage classification due to the difficulty of evacuating particles through the overflow pipes, as well as the reduction due to the installation of pipes, the radial extension of the centrifugal countercurrent classification j; As a result, most of the particles that have already been crushed to the required size are not removed from each step, are subjected to repeated shock loading and are overgrinding, which leads to a decrease in productivity, an increase in the specific energy consumption and wear of the impact elements. In addition, since the diameter of the steps increases as the material moves, c. each stage establishes its separation boundary, and the dispersed composition of the finished dust carried out by the stage of each stage is different. This circumstance reduces the uniformity of the resulting finished powdered product. The purpose of the invention is to increase the productivity of the mill, the uniformity of the fractional composition of the finished powder product, the reduction of specific energy consumption and wear of the impact elements. The goal is achieved by the fact that in a centrifugal mill containing a multistage housing, there is a rotor in it in the form of a vertical shaft carrying a disc. And with impact elements whose diameter increases in the direction of movement of the ground material from top to bottom, overflow pipe, loading and the discharge pipe and the impeller of the fan located at the end of the rotor on the lower disk side, the rotor shaft on the lower disk side is made with a central hole, as well as radial windows, located interdisk spaces. FIG. 1 shows a centrifugal mill, a longitudinal section; in fig. 2 shows section A-A in FIG. 1. The mill comprises a housing 1 with a feed inlet pipe of source material 2f a vertical drive shaft 3 with a rotor 4 carrying disks 5 with impact elements b, a discharge pipe 7. At the rotor face there is an impeller of a fan 8 connected to a central opening 9 which communicates through the radial window 10 with the space between the disks. The space between the first disk and the body is connected

with the space between the last disc and the chassis-flow tube 11 Axial clearance between the discs decreases along the course of movement of the material in accordance with the ratio

/ D.

 No)

where hj and th - axial clearance, respectively

- f between discs of the 1st and (1 + 1) -and steps

° i 1 - internal diameter of the body of the 1st and first stages.

The mill works as follows.

The grind material is fed: through pipe 2, installed in housing 1, falls under impact elements 6 in the first stage and shreds: Dumping into the space between the first and second stage discs, the Material enters the centrifugal zone: but of countercurrent classification, with small particles being blown off by air, created by fan 8, removed through windows 10 of the rotor 4 and through. the central hole 9 and the nozzle 7 enter the finished product, and large particles are thrown by centrifugal forces onto the shock elements of the second stage and crushed, then the process repeats. Large particles, not destroyed in the last stage, are returned to the nepBj stage by the transfer pipe 11. By reducing the gap between the disks in the course of the material in each subsequent stage, the radial component of the air velocity is higher than in the previous one. At the same time, since during the course of the movement the diameter of the step increases, the ratio of the forces acting on the particles (aerodynamic dragging them into the radial windows, and; centrifugal, throwing to the periphery) remains constant. This provides an approximate constancy of the separation boundary and the dispersed composition of particles from different stages carried to the finished product and contributes to an increase in the uniformity of the finished powder.

Due to the highly efficient removal of fine particles from the comminution zone, the energy intensity of comminution is reduced, the uniformity of the finished particle size distribution increases. product, the service life of percussion elements increases.

Claims (1)

A CENTRIFUGAL MILL containing a multi-stage casing, a rotor located in it in the form of a vertical shaft bearing disks with unary elements, the diameter of which increases stepwise along the course? moving the milled material from top to bottom, the regrind pipe, loading and unloading nozzles and the impeller of the fan located on the end of the rotor from the bottom of the disk, characterized in that, in order to increase productivity, uniformity of the fractional composition of the finished product, reduce specific energy consumption and wear of impact elements , the rotor shaft from the bottom of the disk is made with a Central hole, as well as with radial windows located 'at the level of the interdisk spaces.