RU116373U1 - DRUM SCREEN WITH MAGNETIC SYSTEM - Google Patents

Abstract

A drum screen with a magnetic system, consisting of a screen itself, a non-magnetic shell and a magnetic system, which serve to separate the grinding products of a ball mill into two fractions and remove metal scrap, characterized in that the drum screen is installed on the flange of the mill discharge neck, and to its rear a non-magnetic flange is attached to a non-magnetic cylindrical shell, on which magnetic separation occurs by the forces of the magnetic field of the magnetic system, which is installed coaxially with the shell, with a gap, and made in the form of a circular segment, while the chute for removing the scrap is located at an acute angle to the vertical, and the design of the drum screen , made in the form of a truncated pyramid, the side faces of which are sieve, significantly reduces the dimensions, weight and cost of the product.

Description

The utility model relates to mineral processing technology and can be used in the mineral processing industry for ball mills and semi-self-grinding mills, in the construction industry and the chemical industry.

Classifying drum-type devices are known, which are a two-deck drum screen (Redistribution of grinding energy between stages under the conditions of Urupsky GoK / P.V. Malyarov, V.F. Stepurin, G.M.Soldatov, N.D.Konnik / Ore dressing. 2006 No. 3, p. 18-21). The inner deck is used to output metal scrap, and the outer deck is used to separate the size of the products of grinding.

The disadvantage of this design is the inability to withdraw from the mill discharge metal scrap in the form of fragments of worn steel balls. The presence of metal scrap in the circulating load does not allow the use of sand pumps due to the intensive wear of their working bodies. At the same time, metal scrap in the undergrate product of the outer deck of the drum screen significantly increases the wear rate of the working bodies of Sand pumps and hydrocyclones. The presence of metal scrap in the circulating load (up to 8%) reduces the mill productivity in terms of initial nutrition.

The closest in technical solution to the claimed utility model is a hydraulic drum screen with a magnetic catcher for metal scrap (Certificate of the Russian Federation for utility model No. 110003 IPC: V07V, 2011). The drum screen (classifier) is installed on the discharge neck of the mill and consists of front shell (material non-magnetic steel) on the flange of which a drum screen is fixed. The drum screen itself is a multifaceted prism, the side faces of which are sieves, the mesh size of which is regulated by the enrichment process technology. Extraction of metal scrap from mill discharge products is carried out on a non-magnetic shell. The output of metal scrap is carried out due to the forces of the magnetic field generated by permanent magnets (magnetic trap), which is mounted coaxially to the non-magnetic shell.

The main disadvantage of this design is the installation of a magnetic catcher classifying device directly at the pulp exit from the neck of the mill, which leads to significant negative factors in the efficiency of this design:

1. The flow of pulp from the discharge neck of the mill is fed directly to a non-magnetic shell. Pulp has a high viscosity, high speed and considerable volume and mass. This significantly complicates the derivation of metallic inclusions and requires the creation of more powerful magnetic fields, increases the size and cost of the magnetic system. The efficiency of magnetic separation is significantly reduced.

2. The output device for metal scrap (hopper and chute for removing scrap) is installed inside the drum screen, while the chute for output of metal scrap passes along the entire length of the drum screen (up to 1.5 m). The internal dimensions of the screen determine a very small angle of inclination of the gutter, which complicates the spontaneous movement of metal inclusions along it and requires the supply of water to flush them (or install a vibrator).

The technical result achieved by the implementation of the claimed utility model consists in the complete removal of metal scrap from the products of grinding, by dividing the products of grinding into two fractions, increasing the productivity of the initial feed.

The specified technical result is achieved by the fact that immediately after the discharge neck of the mill, a drum screen (classifier) is installed, the mesh size of which is determined by the enrichment process technology. A shell made of non-magnetic steel is attached to the flange of the drum screen, to which a dehydrated product of large classes (over-screen product of the drum screen) is fed. The under-sieve product of a drum screen is sent for classification in hydrocyclones and further regrinding. Metal scrap is removed on a shell made of non-magnetic steel by the action of a magnetic field formed by a magnetic system in the form of a sector based on permanent magnets. The magnetic system (magnetic trap) is mounted coaxially to the non-magnetic steel shell.

Figure 1 shows a schematic diagram of a drum screen with a magnetic system for the withdrawal of metal scrap from the grinding cycle in ball mills and semi-self-grinding mills, where:

1 - one-day drum screen;

2 - magnetic system based on permanent magnets;

3 - shell made of non-magnetic steel;

4 - front and rear flanges;

5 - hopper and gutter for scrap output.

The drum screen (item 1) can be made in the form of a multifaceted prism or a multifaceted truncated pyramid, the side faces of which are sieves (steel, rubber or polyurethane). The determination of the size of the sieve openings d is based on the principle of uniform loading of the mills of the first and second stages, as well as the technology of the enrichment process. The front flange is made of magnetic steel, the shell (key 3) and the rear flange are made of non-magnetic stainless steel. The magnetic system (item 2) is formed on the basis of permanent magnets and is installed coaxially with the shell. The gap between the magnetic system and the cylindrical shell is determined by the characteristics of the magnetic field. The hopper and chute for removing scrap (item 5) are made of non-magnetic material.

Functionally, the proposed device divides the pulp into two fractions (figure 1): small and finished classes; large classes, in addition, metal scrap is displayed. The drum screen (key 1) with the front flange (key 4) is attached to the flange of the discharge neck of the mill. From the mouth of the mill pulp is fed to the working surface of a sieve of a drum screen. Finished and small classes (-d mm) go to the screen, along with liquid, and dehydrated large classes (+ d mm) and metal scrap enter the non-magnetic shell (item 3). Under the action of the forces of the magnetic field of the magnetic system (item 2), the metal scrap rises together with the shell, and in the zone of termination of the forces of the magnetic field it breaks away from the shell, enters the hopper and goes into the box through the gutter. Large classes (+ d) are the circulating load of the first grinding stage, and class (-d) is the discharge of the drum screen, pumps are used for classification in hydrocyclones to highlight the size classes ready for enrichment.

The proposed utility model allows one to completely extract metal scrap from dehydrated large classes, it should be noted that large classes make up only 10-20% of the volume of mill discharge products and this allows the use of a magnetic field of lower inductance. Large classes are dehydrated, which positively affects the quality of magnetic separation. Elimination of metal scrap from the first stage of the mill circulation after a few days of work will lead to the elimination of metal fragments in the product of the discharge of the drum screen (class -d), because small metal fragments occur during the destruction of larger ones.

The chute for the withdrawal of metal from the hopper is located at a small angle (less than 40 degrees) to the vertical, because it does not need to be mounted along the entire length of the drum screen. Metal fragments are removed from the hopper under the action of gravity, the friction force of metal fragments along an inclined pipe is much less than the tangential component of gravity, and therefore does not require additional water supply to flush or install a vibrator.

The design of the drum screen in the form of a truncated pyramid (figure 1), the side faces of which are sowing surfaces, introduces additional advantages to the claimed utility model. The diameter of the non-magnetic flange to which the cylindrical shell is attached decreases to 50%, and therefore the diameter of the shell decreases. In turn, the diameter of the shell determines the size of the permanent magnet magnetic system, which will decrease proportionally, which significantly reduces the cost of the product, because the price of permanent magnets is quite high. A drum screen in the form of a truncated pyramid significantly reduces the weight and dimensions of the structure.

The proposed utility model removes from the circulating load of the mill metal scrap, which is up to 8%, in unloading products, which will allow to increase the mill productivity by initial feed by this value. Elimination of metal scrap will allow the use of sand pumps to transport the circulating load, instead of bulky and energy-intensive spiral classifiers. Removing metal scrap from the drain of the drum screen allows you to increase the life of the pumps and hydrocyclones.

Claims (1)

A drum screen with a magnetic system, consisting essentially of a screen, a non-magnetic shell and a magnetic system, which are used to separate the products of grinding a ball mill into two fractions and output metal scrap, characterized in that the drum screen is mounted on the flange of the discharge neck of the mill, and to its rear a non-magnetic cylindrical shell is attached to the non-magnetic flange, on which magnetic separation occurs by the forces of the magnetic field of the magnetic system, which is installed coaxially with the shell, with a gap , and made in the form of a circular segment, while the chute for outputting scrap is located at an acute angle to the vertical, and the design of a drum screen made in the form of a truncated pyramid, the side faces of which are sieves, significantly reduces the dimensions, weight and cost of the product.