RU2199403C2 - Finely dispersed material separation method - Google Patents

Abstract

FIELD: mining, chemical, food-processing industry, metallurgy. SUBSTANCE: method involves separating finely dispersed materials by size in centrifugal flows through sieving surface by feeding and separating material in movable turbulent flows created in boundary layer of sieving surface. Material is fed inside sieving surface in the form of gaseous suspension. Turbulent flow is created by means of blades rotating at frequency of 50-200 Hz. Method may be used in minerals concentration. EFFECT: increased efficiency and improved quality of separation of materials. 2 dwg, 1 tbl

Description

 The invention relates to the separation of finely divided materials by size and can be used in mineral processing, as well as in the metallurgical, chemical and food industries.

 To separate dispersed materials by size through a stationary or rotating spherical screening surface, centrifugal flows created by tangential feed of the material or by mechanical mixing are used (see Guide to ore dressing. Preparatory processes. TI, M .: Nedra, 1982, p. 33- 53).

 The disadvantage of these methods is the low separation efficiency for small size classes (less than 50 microns) due to clogging of the screening surface by large particles.

 A known method of separating the grain mixture in centrifugal flows through a system of rotating screening surfaces when feeding the source material to the screening surface at a speed that maintains particles in suspension (see AS 1371717, 07 V 1/00, B.I. 5 1988).

 The disadvantage of this method is the decrease in productivity and separation efficiency over time due to clogging of the screening surface by particles whose size exceeds the size of the holes of the screening surface.

 There is a method of sorting grinding products through a screening surface with mechanical cleaning of the latter, in which the material is sorted in the chamber at an air flow rate of 0.05-0.083 m / s, and at the inlet and outlet of the chamber the air flow rate is 19-27 m / s (see RF patent 2141878, B 07 B 9/00, B.I. 33, 1999).

 The disadvantage of this method is the inability to use it to sort the material with a high density due to the deposition and accumulation of large particles on the screening surface.

 A known method for the classification of bulk materials with mechanical casting of material on a cylindrical screening surface (see AS 1404124, 07 1/24, B.I. 23, 1988).

 The disadvantage of this method is the low separation efficiency due to the reduction of the living cross-section of the screening surface with coarse-grained material, which due to the large mass under the influence of centrifugal flows is concentrated on the screening surface.

 There is also a method of separating finely divided materials by size in centrifugal flows through a screening surface, including the separation of material in moving turbulent streams created in the boundary layer of the screening surface (see SU 1238813 A1, 06/23/1986, B 07 B 7/083, prototype).

 The disadvantage of this method is the large wear of the screening surface due to the abrasive action of the starting material and mechanical cleaning.

 The aim of the present invention is to increase the efficiency of separation by size of finely divided materials.

 This object is achieved by the fact that in the method for separating finely divided materials by size in centrifugal flows through a screening surface, including feeding and separating material in moving turbulent streams created in the boundary layer of the screening surface, according to the invention, the material is fed into the screening surface in the form of an air suspension, and turbulent the flow is created by blades rotating with a frequency of 50-200 Hz.

 The essence of the proposed method is as follows. Inside the concave or spherical screening surface, the initial aerosuspension is fed, which is rotationally driven mechanically, for example with a paddle mixer. Under the action of centrifugal forces, the material is concentrated at the screening surface and is divided into two fractions: oversize (coarse-grained) and sublattice (fine-grained). When the blades move, the stall character of the flow of the aerosuspension occurs. As a result of this, a turbulent nature of the flow arises behind the blades in the form of vortex flows. The dimensions of turbulent disturbances depend on the distance between the mixer blades and the screening surface, as well as on the speed and frequency of rotation of the blades.

 In this case, there is a change in the magnitude of the direction of pressure (P) and speed (V) of the movement of the aerosuspension in the boundary layer of the screening surface (Fig. 1). Due to the pressure drop, large particles are primarily involved in the vortex region from the screening surface as having a large mass, as well as particles of a flat shape with a large windage. As a result of this, the screening surface is cleaned of large particles and the passage of small particles through it is accelerated due to the pressure drop in the volumes separated by the screening surface. Large particles are discharged at the end of the screening surface through an adjustable hole.

 The separation efficiency of the proposed method depending on the size of the starting material and the requirements for the composition of the separation products can be controlled by changing the distance between the blades and the screening surface, as well as the frequency of turbulence created by the rotating blades, 50-200 Hz.

 Moreover, with a decrease in particle size (d) of the emitted material, an increase in the frequency (f) of turbulence is required (Fig. 2).

 From the data in the table it follows that the proposed method of separation in comparison with the prototype provides an increase in the efficiency of separation of small-sized mica in the class of 10 μm by 20%.

Claims (1)

 A method for separating finely dispersed materials by size in centrifugal flows through a screening surface, including feeding and separating material in moving turbulent streams created in the boundary layer of the screening surface, characterized in that the material is fed into the screening surface in the form of an aerosuspension, and the turbulent flow is created by rotary blades rotating with a frequency of 50-200 Hz.

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