RU2010605C1 - Centrifugal mill - Google Patents

Abstract

FIELD: crushing hard materials. SUBSTANCE: mill has shell 1, loading chute 2, discharge chute 3. inlet pipes 4, outlet pipes 5, speed-up rotor 6, impact ring 7 concentrically and with clearance positioned relative to rotor, chamber 8 surrounding impact ring 7 and intended for lifting fine fractions, and separating ring mounted in the upper portion of chamber. C-shaped self-lining cross-section impact ring is mounted to rotate in direction opposite to rotor rotation with a clearance of 0.7 of height of impact ring inner space. Separating ring 9 is made in the form of flat disk with radial spokes. Material to be ground is fed through loading chute 2 to center of rotating rotor 6, accelerated there and thrown with high speed onto self-lining impact surface of impact ring 7 and broken there mainly by grinding. EFFECT: high quality of grinding. 2 cl, 3 dwg

Description

 The invention relates to devices for grinding solid materials, mainly briquettes, obtained by grinding cement clinker, cement raw material mixture, granulated blast furnace slag, coal, iron ore and other mineral raw materials by compressing a layer of material with high pressure in roller grinders, and can be used in construction grinders , mining and other industries.

 A device for grinding material is known, comprising a cylindrical body with an inlet chute, in which a rotor with concentric rows of grinding elements is installed on a horizontal shaft, between which rows of grinding elements of the stator are placed, an opening for removing the fine fraction, a swirl chamber with holes for supplying air and rough discharge fractions made on the periphery of the turbulence chamber body, the hole for removing the fine fraction is placed coaxially with the rotor, and a spiral is mounted on the cylindrical part of the body guide rail.

 The disadvantage of this device is the large size, low efficiency when grinding small fractions of the material.

 Known chopper, which contains a housing with oppositely rotating inside of it rotor rings with ribs forming a grinding chamber; the ribs are located at a negative angle to the direction of rotation of the rotor rings, the number of ribs on the rotor rings increases to unload the material.

 The disadvantage of this grinder is the high abrasive wear of the working elements and the low efficiency of grinding fine fractions with increased energy consumption.

 A device for grinding material is known, comprising a rotating casing and crushing chambers coaxially located underneath one another with a vertical feeder turning into horizontal tubes directed perpendicularly to the fender elements, and a grinding chamber with a discharge device; the breaker elements are made in the form of crushing plates rigidly fixed to the walls of the crushing chamber, the loading device is made in the form of a hollow shaft communicated with the air duct system with a perforated tip installed in the interface between the crushing and grinding chambers.

 The disadvantage of this device is the insufficient efficiency of grinding small fractions of the material, it is necessary to improve the process of self-grinding.

 A device for grinding and separating material is known, comprising a housing with inlet and outlet nozzles, a rotor with blades and a casing in the form of a truncated cone, mounted concentrically inside the cone, characterized in that, in order to increase the efficiency of grinding and separation of the material, it is equipped with concentric and sequential behind a casing with clearances, a cage, a stepped casing with a scapular grill and a protective screen bent towards the scapular lattice, the smaller base of the casing being provided with a guide with a barking element, a larger one with a diaphragm, and gates are mounted in the outlet pipes; while the stepped shell is made in the form of two concentrically arranged cylinders connected by a partition.

 The disadvantages of this device, adopted as a prototype, are the high abrasive wear of the working elements, the insufficient efficiency of grinding small fractions and increased energy consumption.

 The aim of the invention is to increase the efficiency of grinding and separation while reducing energy consumption, as well as increasing the service life of the working bodies.

 The goal is achieved by the fact that in the proposed mill, comprising a housing, loading and unloading chutes, inlet and outlet pipes, an accelerating rotor, a breaker ring concentrically located with a gap relative to the rotor, surrounding the last small fraction lifting chamber and a separation ring installed in the upper part of the chamber, the latter is made in the form of a flat disk of radial spokes, and the baffle ring has a C-shaped self-lining cross section and is installed with the possibility of rotation in the opposite ohm rotor direction, wherein the size of the gap between the rotor and the pneumatic ring cavity height equal to 0.7 the baffle ring.

 The design of the separating ring in the form of a flat disk of radial spokes is due to a reduction in energy consumption for its rotation due to the lower aerodynamic drag of the spokes compared to the impeller blades. It was found that an experimental comparison of the possibilities of separation of the impeller blades and the alternative option, round rods, showed their equivalent effectiveness. In addition, round rods proved to be more durable in operation due to better abrasion resistance compared to flat impeller blades.

 A separating ring having a C-shaped self-lining cross section and mounted rotatably in the opposite direction to the rotor provides a positive effect for the following reasons: as a result of the oncoming movement of particles of material flying out of the accelerating rotor and located on the self-luting surface of the breaker ring, located relative to each other with the smallest possible gap, conditions are provided for grinding the material by the abrasion method, which is the most effective ivnym fracture predominantly fine-grained materials such as cement clinker after its preliminary crushing of the material layer by compressing in high pressure roller press mill. In addition, with the opposite rotation of the accelerating rotor and the breaker ring, the grinding efficiency is increased by increasing the relative speed of the interacting particles of the material; the amount of clearance (A) between the rotor and the baffle ring is determined below by the following considerations.

To prevent the rotor from touching the self-lining surface of the baffle ring during mill operation (in order to avoid mutual friction), the following condition must be fulfilled:
A≥H˙tgα,
where A is the gap between the outer diameter of the rotor and the inner diameter of the baffle ring;
H is the height of the open cavity of the C-shaped cross section of the jack ring;
α is the angle of repose of the material on the self-lining surface of the rotating baffle ring.

G = m ˙g, где m - масса частицы;
v - линейная скорость частицы, равная окружной скорости самофутерующейся поверхности отбойного кольца;
R - средний радиус самофутерующейся поверхности отбойного кольца;
g - ускорение свободного падения частицы материала.A centripetal force F _c and a gravity force G act on a particle of material located on the self-lining surface of the baffle ring (see Fig. 3), while:
F _n = F _n =

G = m ˙g, where m is the particle mass;
v is the linear velocity of the particle equal to the peripheral velocity of the self-lining surface of the baffle ring;
R is the average radius of the self-lining surface of the baffle ring;
g is the acceleration of gravity of a particle of material.

A particle of material can move along the self-lining surface of the baffle ring provided that:
T ≥ F _Tr , where T is the projection onto the slope plane of the self-lining surface of the baffle ring of the forces acting on the particle (F _c and G);
F _Tr - the force of resistance to the movement of particles along the slope (friction force).

Wherein:
T = F _c ˙sinα <N> + G˙cosα <N>;
F _Tr = f˙F _c cosα-G˙sinα, where f is the coefficient of friction of a material particle on the self-lining surface of the baffle ring.

Given the large difference values, and the centripetal force of gravity (F _q>> G), acting on the particle material, the force of gravity G is excluded from the calculation.

Then:
F _c ˙sinα≥F _c ˙f˙cosα or
sinα≥f˙cosalpha <N>
When rubbing cement clinker on the clinker f = 0.5-0.7.

Accepting f = 0.7, we get:
tg α≥ 0.7
α = 35 ^o
The clearance between the rotor and the baffle ring should be equal to:
A≥H˙tg35 ^o ≥0.7˙H
Based on the foregoing, it is accepted:
A = 0.7 N.

 In FIG. 1 schematically shows the proposed centrifugal mill; in FIG. 2 - top view; in FIG. 3 - grinding chamber.

 The mill comprises a housing 1, a loading chute 2, a discharge chute 3, inlet pipes 4, outlet pipes 5. an accelerating rotor 6, a breaker ring 7, a lift chamber 8, a separation ring 9.

 The proposed centrifugal mill operates as follows.

 The source material is fed through the feed chute 2 to the center of the accelerating rotor 6, which rotates in a given direction, where it accelerates and, flying out of the rotor, is destroyed by mainly abrasion of the material layer on the self-lining surface of the breaker ring 7, which rotates, for example, through a planetary gear 10 in the opposite direction to the accelerating rotor. The crushed material under the action of gravity along the inner cone of the housing 1 is poured down into the separation chamber 11, where it is sifted with a thin annular stream through a perpendicular stream of circulating air, which separates the fine fraction from the unmilled material. The latter enters the hopper 12 and through the discharge pipe 13 and discharge chute 3 is sent for re-grinding. A small fraction of the material is transported by a circulating air stream through the lifting chamber of the fine fraction 8 and a rotating separating ring 9 into the outlet pipes 5. In this case, only a part of the fine fraction passes through the separating ring, since its larger particles moving in an upward air flow with less speed, discarded by the needles 14 of the separating ring to the walls of the housing and when they lose the centrifugal impulse, they are poured under the action of gravity into the hopper 12 along with the under-ground material. By changing the width of the radial slots of the separating ring due to the number of knitting needles and adjusting the circulating air flow, it is possible to shift the separation boundaries towards fine fractions or to roughen the finished product.

 The circulating air flow is created by a fan located outside the mill, and the finished product is deposited from it in external cyclones.

 Using the proposed invention will significantly improve the efficiency of grinding and separation, reduce energy consumption, and also increase the service life of working bodies. (56) Copyright certificate of the USSR N 1577139, cl. B 02 C 13/22, 1985.

 USSR author's certificate N 1187873, cl. B 02 C 13/14, 1984.

 USSR author's certificate N 1168284, cl. B 02 C 13/14, 1984.

Claims (2)

 1. CENTRIFUGAL MILL, comprising a housing, loading and unloading chutes, inlet and outlet pipes, an accelerating rotor, a breaker ring concentrically located with a gap relative to the rotor, surrounding the last fine fraction lifting chamber and a separation ring installed in the upper part of the chamber, characterized in that, in order to increase the efficiency of grinding and separation processes while reducing costs, as well as increasing the life of working bodies, the separating ring is made in the form of a flat disk of radial sp Itz, and the baffle ring has a C-shaped section and is installed with the possibility of rotation in the opposite direction to the rotor.  2. The mill according to claim 1, characterized in that the gap between the rotor and the baffle ring is equal to 0.7 of the height of the cavity of the baffle ring.

Images