RU2249484C2 - Method for grinding of bulk materials in cone vibratory grinder - Google Patents

Abstract

FIELD: equipment for grinding of bulk materials, preferably resilient materials.

SUBSTANCE: method involves feeding bulk material and grinding between movable and immovable cones; creating bulk material vibratory fluidization mode in converging annular gap between movable and immovable cones at vibration intensity γ=αω²/g>10, vibration amplitude α≤10^-3 m of movable grinding cone; removing resulting ground product by means of adjustable air flow through particles delivered for grinding process.

EFFECT: provision for producing of fine powders of bulk materials in continuous operating mode, increased efficiency and reduced consumption of power.

1 dwg

Description

The invention relates to techniques and technologies for grinding bulk materials with predominantly elastic properties, and can be used in food, pharmaceutical, chemical, mining and other industries to obtain finely dispersed powders.

Closest to the technical essence of the proposed is a method of grinding bulk materials in a conical vibration grinder, including feeding and grinding between movable and fixed cones. REVNIVTSEV V.I. et al. Vibrational disintegration of solid materials. M .: Nedra, 1992, p.218-221.

The vibration fluidization mode created by grinding by this method limits the basic principle of vibration grinding - the higher the frequency of force acting on a solid, the less stress it breaks and the greater the degree of grinding and the smaller the size of the resulting particles.

The objective of the invention is to increase the degree of grinding in cone vibration grinders, obtaining fine powders.

This problem is achieved in a method of grinding bulk materials in a cone vibration grinder, including feeding it and grinding between the movable and fixed cones, while in the converging annular gap between the movable and fixed cones, a vibratory mode of bulk material with a vibration intensity of λ = αω ² / g> 10 is created , the oscillation amplitude α <10 ^-3 m of the crushing movable cone, and the grinding product is removed by controlled upward air flow through the particles entering the grinding.

The drawing shows a diagram of an inertial cone vibration grinder for grinding bulk materials in the mode of vibration boiling.

The chopper contains a loading funnel 1 with a slide valve 2, a movable inner cone 3 and a fixed outer cone 4, fixed in the pallet 5 by means of a thread. The pallet is provided with openings 6 with shutters. The evacuation chamber of grinding products 7 is mounted on a fixed cone 4 and is equipped with a pipe for supplying air 8 and a pipe for removing products of grinding 9.

Bulk material from the funnel 1 through the gate valve 2 is continuously fed to the upper part of the movable cone 3 and, under the influence of vibrations of the latter, is discharged into the working zone formed by the cones 3 and 4. The layer of granular material enclosed between the cones obtained under the condition of a continuous dosed supply is subjected to a high-frequency power exposure with vibration intensity λ = αω ² / g> 10. Particles receive the greatest force in the annular zone "A", as a result of which they are destroyed. In zone "B" under the influence of high-frequency oscillations, a vacuum occurs, and the dependence of the vacuum under the vibrating boil layer on the vibration frequency is approximated by the expression [4]:

where P _{about the} pressure under the vibro-boiling layer; P _a - atmospheric pressure;

k is the coefficient of proportionality.

From the expression it follows that the magnitude of the vacuum under the vibro-boiling layer exponentially depends on the oscillation frequency of the movable cone 3.

The air supply under the vibratory boiling layer through a layer of granular material is difficult due to its high aerodynamic resistance. Air enters through the lower slot between the crushing cones, and its quantity and, consequently, the vacuum depth in zone “B” is regulated by dampers in the openings 6. The movement of the ascending air stream through the working zone carries out finely divided grinding products through a descending stream of 7 particles entering the evacuation chamber . From the evacuation chamber 7, the grinding products are removed by air passing through the nozzles 8 and 9 into the aspiration system. The oscillation amplitude of the crushing cone, determined by the size of the gap between the cones, should not exceed 1 mm, since according to the results of studies, with an increase in the gap, the vacuum under the vibro-boiling layer drops sharply and the material from the working area begins to wake up in the pallet 5, without reaching a finely dispersed state.

The process of destruction of bulk materials and the final size of the grinding products is governed by vibration parameters (amplitude and frequency), the magnitude of the force exerted on the particles (centrifugal unbalance force), as well as the speeds of the air flows passing through the converging annular gap between the cones and the evacuation chamber.

The advantages of the proposed method of grinding are in the high-frequency nature of the impact on the material, which increases the rate of destruction of particles, reduces the energy intensity of the process and creates conditions for high controllability of the process in order to obtain particles of a given size.

The creation of high-frequency vibrations of the crushing movable cone of the vibration mill is possible not only by mechanical (eccentric and inertial) vibration exciters, but also by other types of vibrators, for example electromagnetic.

Claims (1)

A method of grinding bulk materials in a cone vibration grinder, including feeding it and grinding between a movable and fixed cones, characterized in that in the converging annular gap between the movable and fixed cones, a vibratory mode of bulk material with a vibration intensity of λ = αω ² / g> 10, amplitude oscillations of the crushing movable cone α ≤ 10 ^-3 m, and the grinding product is removed by controlled upward air flow through the particles entering the grinding.