SU1364377A1 - Method of separating loose materials - Google Patents

Abstract

The invention relates to the technology of obtaining powder materials. used in the industry of building materials, food, electronic, etc. The purpose of the invention is. NIN - improving the efficiency of classification of bulk materials with particle sizes of 1-100 microns due to the disaggregation of particles at the time of entry of aerospace into the separator. For this, the bulk material is accelerated in the gas stream to 1, 8-1, 8-10 m / s. Then the air suspension is introduced into the separator, for example, into a gravity or inertial dust collector. Coarse particles are released from the gas stream due to gravitational or inertial forces. Small fractions were carried out by the gas stream. This range of accelerations effectively destroys any aggregates of powdered substances formed due to the action of dispersive, capillary and electric forces between particles. 2 tab. with o (L

Description

with

long, 8 meters long

The invention relates to the technology of obtaining powdered materials, and more specifically to those cases where there are increased requirements for the composition of the particles used, in particular, the building materials industry, the food industry, the electronic industry, etc.

The aim of the invention is to improve the classification efficiency of bulk materials with a particle size of 1-100 microns due to the disaggregation of particles by the time the aerospace suspension enters the separator.

Example 1. A separation method using a TsN-15 reciprocating cyclone is used. The acceleration range of 8, -10 units. They are realized by passing air, aerosol particles before being fed into the separator (cyclone) through a spiral tube with an internal number of turns having a radius of curvature R of 0.02 m. The maximum size of the original particles is 9.7 microns. In all cases, the necessary accelerations are achieved by changing the pressure at the inlet to the channel. After tangential entry of a stream with particles into a cyclone, a large fraction inside the inertial dust collector is released in it due to inertial forces, the removal of small fractions by the gas flow of the dust collector.

In all cases, the process is controlled by changing the overpressure at the inlet to the channel.

In tab. 1 shows the experimental data. ,

EXAMPLE 2. A range of 51 to 8.310 units of particles is introduced into the gas stream by means of a fluidization chamber, and these accelerations are ensured by the collision of the blades of the agitator with the powder particles. The necessary accelerations are obtained by varying the rotational speed of the agitator. Experimental data are given in table. 2 and for comparison, data are given when the mixer does not work, i.e. . The separation of particles takes place in a dust precipitation chamber (gravitational dust collector) and consists in introducing particles in the gas stream into the dust precipitation chamber, separating large fractions inside the chamber due to gravity and carrying out

small fractions from the chamber. The maximum rotation speed of the agitator is rpm. The radius of the blades of the agitator, 02 m. The flow rate of the air passing through the fluidization chamber and the dust precipitation chamber is constant in all cases and equals Q 3-10 M / s. The maximum particle size of 0 particles is 1 d after separation in a dust precipitation chamber is dp 30 microns, and for the initial particles 65 microns.

The resulting accelerations may be of various origins, for example

5 accelerations due to the frictional force of the moving relative to the gas flow particles, acceleration due to impacts, centripetal accelerations, etc. It is also possible that there are several reasons for the acceleration of particles. However, in each specific case, the absolute value of the sum of the obtained accelerations plays a decisive role. Separation

5 particles are carried out in gravitational or inertial dust collectors, which in practice are commonly used for the purposes of dust collection, rather than particle separation. However if

0 the particles are dispersed before the separation by the proposed method, it becomes effective to use dust-collecting equipment and for the purposes of; In this case, gravity dust collectors or dust precipitation chambers can be used: numerous class of inertia dust collectors. Each structure can in principle be used for

0 separation in the entire size range of 1-100 µm with varying degrees of separation of fines, but it is practically more convenient to use each design in a specific

4g particle size range, since the efficiency of their release strongly depends on their size. So, for example, for sizes of 20-100 microns, it is preferable to use dust-collecting chambers and louver dust collectors, for sizes 5-20 microns - reciprocating cyclones, for sizes 1-5. μm — water film cyclones and venturi scrubbers, etc.

The proposed range of accelerations makes it possible to effectively destroy any aggregates of powdered substances formed due to the effect between the dispersion particles C (capillary p5

50

55

31364377

electric forces, up to the destruction of the material of the particle itself. The upper limit is chosen from that

By

the fact that during accelerations of units, g (9, m / s), the materials of all known powdery substances are destroyed, thus using the proposed method, along with separation, grinding occurs, the intensity of which is determined by the amount of accelerations achieved and the mechanical characteristics of the material of the particles.

In order to substantiate the lower limit of accelerations, the causes of particle cohesion should be considered in more detail. As is well known, the cohesion of particles among themselves is explained by three kinds of forces, namely: molecular or van der Waals forces, capillary forces, FH; electric forces, F.

Since the molecular interaction is 2 orders of magnitude smaller than the capillary, they can be neglected.

The general expression for the force F acting between particles has the form, 2.0840 d + 0.228d + l, 44, 230d + l, 44, N.

The above analysis does not claim to be exhaustive, but it gives an idea of the operating forces and, accordingly, of the accelerations necessary to overcome them.

Mass of a spherical particle

kg

where p4 is the density of the particle material.

Take p 4000 kg / m, then d, kg.

The acceleration expression for the two particles to be aggregated is

a - 1.1040 d% 6.88, m / s

Substitute in this expression um

and, we have, 8-10 m / s or e

ten

1.8-10 units

When working with pre-dried powders and at a humidity of less than 50%, the term that takes into account the capillary interaction disappears, but this increases the effect of electrical interaction due to a decrease in surface conductivity and a corresponding increase in Coulomb (free) charges due to a decrease in leakage.

Thus, the lower acceleration limit of the particles before entering them into the compactor is 1.8–10 m / s, which is much higher than the accelerations achieved by the particles using known methods, as a result of which

from tab. 1 and 2, the yield of particles with a maximum size of 1-100 microns during their separation increases.

Claims (1)

Invention Formula The method of separation of bulk materials, including the acceleration of bulk material in the gas stream and the introduction of aerosol in the separator, the collection of separation products, characterized in that, in order to improve the classification efficiency of bulk materials with particle sizes of 1-100 microns due to disaggregation of particles by the time the aerospace is introduced into the separator, the bulk material in the gas flow is accelerated to 1.8-10. -9.8-10 m / s. Acceleration when striking the canal walls (average for Malshev a, unit g Total acceleration Za, units g Pressure at the channel inlet, P ,,, atm Maximum size of particles squeezing from cyclone ipvojf micron The proposed method 7.24-1о 1.54-10 6.43-10 Z., 6-10 7.86-10 8.1-10 1, 33-10 2.64-10. 5.58-10 1.0-10 1,051,201,502,02,53,5 7.0 3.8 3.2 2.8 2.2 1.9 J 3.2 2.8 2.2 1.9 Options Centripetal accelerator1 not (average), units g 8.61.10 1 5.75-10 Tl, 90.lo Ts.lS-lO I 4.78-10 Iz.U lo 80 45 34 , 25/1 28/2 98 / A 10/0 65/0 72/1 Known method The content of particles with a size smaller than d, p of the total mass of the separated particles (by weight) at dp "const, 2 The output of the separated particles from the total mass of the initial particles, Z  µm4 / 0 14/0 Rotation speed agitators p, rpm О 100 500 Maximum circumferential speed of rotation, m / s , 0 0.209 1.04 03 10 7 38 52 99 59 38 12 20 25 Continuation of table 1 27 18 12 100/15 96/8 100/24 100/14 25/0 2000 5000 7,000 4.18 10.4 14,618 23 27 57 60 60 25 17 13 28 36 40