SU990303A1 - Counter-flow jet mill - Google Patents

Description

one

The invention relates to the technique of fine grinding and the classification of solid materials and can be used in the chemical, pharmaceutical and other industrial fields.

Counterflow jet mills are known for grinding bulk materials, including a grinding chamber, coaxially arranged grinding ejectors, a power supply system and a classification system for ground material, 1.

The disadvantage of these mills is the low grinding efficiency due to the imperfect classification system for the ground product.

The closest technical solution to the invention is a jet mill, which includes a grinding chamber with oppositely mounted ejectors and a centrifugal cyclone classifier connected to it, equipped with an internal, located along its axis, discharge branch pipe Z The disadvantage of this mill is the low efficiency of selection of small fractions and increased specific energy consumption for grinding material.

The purpose of the invention is to increase the efficiency of the selection of fine fractions and reduce specific energy consumption for grinding the material.

This goal is achieved by the fact that in a counter-flow jet mill comprising a grinding chamber with oppositely mounted ejectors and a centrifugal classifier connected to it, equipped with an internal branch pipe located along its axis, the classifier is equipped with a receiving cylindrical chamber with tangentially connected pipelines returning to the ejectors. material, and the body of the grinding chamber is made tangentially slotted inlets for air.

In addition, for adjusting the size of the final product in this mill, the outlet nozzle is movable along the axis and has a replaceable nozzle.

FIG. 1 is a schematic diagram of the proposed device; in fig. 2 - section A - A in FIG. one; in fig. 3 shows a section BB in FIG. one.

The countercurrent jet mill consists of a grinding chamber 1 with oppositely mounted grinding ejectors 2, having nozzles 3 for power supply and accelerating pipes 4, as well as a classifier 5 equipped with a cylindrical receiving chamber 6 with return pipes to the ejectors of incompletely crushed material tangentially connected to it.

The grinding chamber body 1 is made in the form of a body of rotation and has tangential slotted inlets 8 for drawing air from the atmosphere.

The classifier housing is a cylindrical shell 9 inside which a screw blade 10 is installed. The receiving cylindrical chamber has an input 11 for feeding the raw material into the mill, as well as a movable outlet nozzle 12 with a replaceable nozzle 13.

Countercurrent mill mill works as follows.

The compressed air supplied to the ejectors 2 through the nozzles 3 ejects the aero-suspension of the coarse fraction and the starting material coming from the receiving cylindrical chamber 6 through pipelines 7 and accelerates it in the accelerating tubes 4.

As a result of the counter impact of the particles of the aerosol of oppositely directed jets, the material is crushed.

In the housing of the grinding chamber, the aerosol mixture is diluted with air drawn from the atmosphere through the slit inlets 8.

Due to the tangential arrangement of the pipelines 7 of the receiving cylindrical chamber 6 in the grinding chamber body and the classifier, the flow of aero-suspension moving from top to bottom is twisted.

The tangential {target inputs on the grinding chamber housing, as well as the propeller blade in the classifier housing, contribute to the intensification of the swirling flow.

In the swirling flow of aero-suspension, centrifugal forces arise, under the action of which the solid particles of aero-suspension, as heavier, are thrown to the periphery. After the passage of the helical blade, the flow of aero-suspension is divided into two flows, one of which moves along the wall of the shell 9 into the receiving cylindrical chamber 6, and the second from the wall to the replaceable nozzle 13 of the branch pipe 12.

The particles of the material, besides the centrifugal force, are affected by the aerodynamic force created by the exhaust fan inside the branch pipe 12.

The magnitudes of these forces determine the nature of the movement of the material particles. By changing the position of the branch pipe and its cross-sectional area by installing a replaceable nozzle, adjustment of the size of the finished product is performed.

Testing has shown that

compared to the famous use

the invention allows to increase the efficiency of the selection of fine fractions and reduce

specific energy consumption for grinding.

Claims (2)

Invention Formula I. Countercurrent jet mill, which includes a grinding chamber with oppositely mounted ejectors and a centrifugal classifier connected to it, equipped with an internal, located along its axis branch pipe, characterized in that, in order to increase the efficiency of selection of small fractions and reduce the specific energy consumption for grinding of the material, the classifier is equipped with a cylindrical receiving gauge with tangentially connected pipelines returning to the ejectors of undersized material tangentially to it, and the housing The chamber is made with tangentially slit inlets for air. 2. Mill according to claim 1, characterized in that that, in order to adjust the size of the selection of the finished product, the branch pipe is made movable along the axis and has a replaceable nozzle. Information sources, taken into account in the examination 1.Akunov V.I. Jet mill. M., “Mechanical Engineering, 1967, p. 108, fig. 49, 50. 2. USSR author's certificate No. 116814, cl. In 02 C 19/06, 1958 (prototype). ";;, Air from the atmosphere 1 Fig.Z 8ff3ffi / J ((3 atmospheres