GB2150043A

GB2150043A - Apparatus for crushing loose granular materials

Info

Publication number: GB2150043A
Application number: GB08331496A
Authority: GB
Inventors: Vladimir Ivanovich Syrovatka; Stanislav Grigorievi Kartashov; Valery Alexeevich Denisov; Valentin Vasilievich Fokin
Original assignee: IZHEV SELSKOKHOZYAISTVENNY I; VNII ELEK SELSKOGO KHOZYAISTVA
Current assignee: IZHEV SELSKOKHOZYAISTVENNY I; VNII ELEK SELSKOGO KHOZYAISTVA
Priority date: 1983-11-25
Filing date: 1983-11-25
Publication date: 1985-06-26
Also published as: GB8331496D0; AU2196483A; DE3342765C2; AU571472B2; DE3342765A1; GB2150043B

Abstract

This invention concerns devices for crushing loose, particularly granular materials. The apparatus comprises a grain pipe (1) and a housing 2 having arranged therein a feed hopper (3) and several grinding stages arranged in succession relative to the vertical axis of the apparatus. Each grinding stage has a spinning disk (5), a slide chute 11, a recoil baffle (4), and a tapered funnel (6). Further, mounted in each of the grinding stages are a defector board (14) and an electrostatic separator (8) having the form of outer and inner cylindrical ring elements of equal height disposed concentrically between the deflector board (14) and slide chute (11) at one level relative to the vertical axis and connected by means of insulators (19). The recoil baffles 4 and tapered funnels (6) have terminals for applying an electric current thereto. The device according to the invention can be used most successfully in fodder production and for crushing mineral components. <IMAGE>

Description

SPECIFICATION Apparatus for crushing loose granular materials This invention relates to the art of crushing loose granular materials. More specifically it concerns centrifugal multistage crushers adaptable for use in secondary (fine) crushing basic materials in the mining, metallurgical, chemical and ccment industries. It is also applicable for fodder production in agriculture and for the production of various construction materials.

The use of the proposed apparatus is especially effective for grinding granular and mineral components in the production of combined fodder. The device embodying the present invention makes it possible to divide granular and mineral components of a combined fodder being prepared when raw stuff is added thereto regardless of its moisture content.

In an apparatus for crushing predominantly loose granular materials comprising a grain pipe, a housing having arranged therein a feed hopper and several grinding stages disposed in succession relative to a vertical axis of the apparatus, each of these stages having a spinning disk, a slide chute, a recoil baffle insulated from the housing, and a tapered funnel, according to the invention. each grinding stage is provided with a deflector board and an electrostatic separator having the form of outer and inner cylindrical ring elements of equal height concentrically arranged between said deflector board and slide chute at one level relative to the vertical axis and connected by means of insulators, the recoil baffles and tapered funnels being provided with terminals for applying an electric current thereto.

Alternatively, the inner surface of the baffles may have the form of a truncated cone tapering toward the feed hopper.

Preferably, in every grinding stage of the apparatus the surfaces of vanes of the spinning disks are corrungated.

This arrangement of the apparatus according to the invention makes it possible to efficiently carry out separation of the material and attain a required homogeneity of the material being crushed in terms of its granulometric composition.

The essence of the invention resides in improving the separation of loose granular material being crushed in grinding stages through the provision of electrostatic separators. These separators operating on the principle of deviation in the path of travel of charged particles of the material being crushed in an electrostatic field afford to thoroughly size the material subsequent to crushing at each stage of grinding. Operating efficiency of the separators of each grinding stage depends on the magnitude of constant voltage applied to the ring elements of the separators through the non-detachable terminals.

Research has shown that for the apparatus according to the invention the plates of the separators are preferably shaped as cylindrical rings connected by insulators. For improving the separation process in stages of grinding the recoil baffles are shaped as truncated cones tapering toward the feed hopper. Such an arrangement of the tapered recoil baffles enables to attain a component velocity vector for the crushed material directed toward the slide chutes where the product acquires a charge proportional to its mass and voltage applied thereto. The recoil baffles in each grinding stage are intended to provide directional travel of the product to the working area of the separators. The corrugated configuration of the vanes of the spinning disks promotes crushing of the matorial in the working area of the spinning disks.

More vigorous crushing of the material in stages of grinding facilitates obtaining larger amounts of particles of this material divided to preselected size to be removed by the separator as the finished product. In consequence, the reduction in the share of the material entering a subsequent grinding stage results in substantially reduced amount of energy required for the grinding process.

The proposed construction of the apparatus for crushing loose granular materials makes it possible to reduce the overall amount of energy consumed for grinding a unit of the initial material fed thereinto by 1.16 to 8.57 times. It also enables to obtain finished products with preselected particle size, completely eliminate pulverulent fractions (particle sizes of below 0.25 mm), as well as dispense with hammers and sizing screens susceptible to wear, reduce by 1.12 to 7.64 times the amount of metal required for fabricating the apparatus, improve the stability and reliability of the crushing process, increase the service life of the working parts and components, and improve the operating efficiency of the apparatus.

Other objects and attending advantages of the invention will become more fully apparent from a more detailed description that follows with reference to the accompanying drawings illustrating various preferred embodiments of the invention.

In the drawings: Fig. 1 is a longitudinal section view of one preferred embodiment of the apparatus according to the invention; Fig. 2 is a section taken along ll-ll in Fig.

1; and Fig. 3 shows a top partially cut-away view of a spinning disk of the apparatus according to the invention.

With reference to Fig. 1, an apparatus for crushing loose granular materials comprises a grain pipe 1, a cylindrical housing 2, a feed hopper 3, recoil baffles 4 spaced from the housing 2, spinning disks 5, and tapered funnels 6. The spinning disk, corrugated recoil baffle and tapered funnel make up one grinding stage; the apparatus may have several such stages. The degree to which the loose granular material is crushed in such stages is progressively increased from the first stage to subsequent ones. Underlying each grinding stage are electrostatic separators 8 secured on insulators 7, the separators being comprised of two interconnected cylindrical ring elements of equal height concentrically arranged at one level relative to a common vertical axis. The ring elements of separators 8 of each successive stage are of a larger diameter than those of the preceding stage of grinding.

The recoil baffles 4 functioning together with the tapered funnel 6 as charging electrodes are fixed in place through insulating pads 9 by screws 10. Slide chutes 11 having the form of a cone arse arranged above the recoil baffles 4 to withdraw a crushed fraction of the material. The spinning disks 5 are similar in construction to impellers of centrifugal compressors; they are affixed to a shaft 12 by fasteners 1 3. In order to direct the crushed material toward the interior of the separators 8, the ring elements thereof are provided with deflector boards 14; the inside surface of the recoil baffle 4 has the form of a truncated cone tapering toward the feed hopper 3.

The boards 14 fail to function as charging electrodes and their surface is insulated from the inner ring elements of the separators 8 to which they are attached. The apparatus is secured in a foundation by means of supports 1 5. The shaft 1 2 of the crushing apparatus carrying the spinning disks 5 is disposed centrally and vertically in bearings 1 6 at the top and bottom of the housing 2. The finished product is discharged through outlet ports 17, whereas the product which failed to be sufficiently crushed is discharged from the apparatus through ports 1 8 (Fig. 2).

The inner and outer ring elements of the separators 8 are interconnected by insulators 19 (Fig. 2). The corrugated vanes 20 of the spinning disks 5 are seen best in Fig. 3.

A working voltage of several kV is applied to the ring elements of the separators 8, the magnitude of the voltage applied being controlled depending on the degree to which the loose granular material is to be crushed, composition of the initial material charged into the apparatus and operating conditions of the apparatus. In ordor to transmit an electrical charge to the particles of the granular material during their crushing and travel along the tapered funnel 6 prior to entering the working space of the separators 8, a voltage of several tenths of one kV is applied to the tapered funnel 6 and recoil baffle 4 in each stage of grinding.

The apparatus according to the invention operates as follows.

A loose granular material to be crushed is supplied along the pipe 1 and feed hopper 3 to the first spinning disk 5. The spinning disk 5 acts to suck a flow of air and loose material to promote the movement of this flow in its working passages. Crushing of the material occurs both inside the working passages of the spinning disks and as a result of impact of the granules of the material against the recoil baffles 4.

The inner surfaces of baffles 4 are cone shaped, said cones 4 being disposed with the smaller base of the cone facing upwards to serve in conjunction with the taperod funnels 6 as a crushing zone and as charging electrodes. Particles of the material being crushed obtained at the first stage of crushing while acquiring a charge from the electrodes are caused, under the action of a speed assumed after the impact, the force of gravity and the force produced by the flow of air, to enter the working space between the ring elements of tho separator 8, the potential difference across these ring elements amounting to several kV.

According to the Coulomb's law, under the action of an electrostatic field the material will be separated into a finished product and a fraction which has to be subjected to repeated crushing at the subsequent stages. By varying the voltage applied to the ring elements of the separators 8 is possible to control the process of separation. This capability of changing the course of separation by varying the voltage makes it possible to fully separate the material in the stages of grinding at any operating conditions of the crushing apparatus.Complete classification of the material being crushed at any operating conditions of the crushing apparatus according to the invention enables to obtain uniform granulometric composition of the finally crushed product without pulverulent fractions and reduce the amount of power used for staged grinding by virtue of completely removing the crushed portion from the initial material fed to a successive stage of crushing.

Alternatively, the electrostatic separators may be replaced by detachable sizing screens.

The provision of sizing screens in the form of symmetrically arranged cones also enables to classify the product in stages of grinding.

However, classification of the material being crushed by means of sizing screens may sometimes result in that larger or smaller size particles may join the finished product to thereby affect homogeneity of its granulometric composition. Therefore, the sizing screens in this modification function as a slide chutes.

Claims

1. An apparatus for crushing substantially loose granular materials wherein there are provided a grain pipe, a housing accommodating a feed hopper and several grinding stages successively disposed relative to a vertical axis of the apparatus, each of these stages having a spinning disk, a slide chute, a recoil baffle insulated from the housing of the apparatus, a tapered funnel, a deflector board, and an electrostatic separator in thc form of outer and inner cylindrical ring elements of equal height concentrically arranged between said deflector board and the slide chute at one level relative to the vertical axis and connected by means of insulators, the recoil baffles and tapered funnels being provided with terminals for applying an electric current thereto.

2. An apparatus as claimed in claim 1 wherein the inner surface of the recoil baffles has the form of a truncated cone the smaller base of which faces the feed hopper.

3. An apparatus as claimed in claim 1 wherein in every grinding stage of the apparatus surfaces of vanes of the spinning disks are corrugated.

4. An apparatus as claimed in any of thc preceding claim substantially as described in the description and represented in the accompanying drawings.