RU2657962C1 - Method of making pellets - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to the production of iron ore pellets. Wet charge is fed to the pelletizer by two streams, and the formation of the skull is performed on the bottom of the inclined pelletizer. First stream of charge is introduced into the compressed gas stream with the formation of the gas wet charge stream, the area, which is occupied by the charge and the area free from charge are formed on the bottom of the pelletizer. Nucleation with charge sputtering by means of gas-moisture-charge jet, which is oriented to the skull, is performed in the charge-free area so that dense layer of wet charge is obtained. Division of the mentioned dense layer into the nucleation centers is carried out, and the skull is purified from the nucleation centers by the rotating drum with ribs. Roll of nucleation centers is formed in the idle area of the pelletizer to the lower part of the pelletizer bottom, until the nucleation centers are filled with the second stream of charge upstream the pellets. In this case, the roll of nucleation centers in the idle area of the pelletizer into the lower part of the pelletizer is accelerated by means of the rotating drum with the ribs, the drum is provided with the drive, after which at least 10 nucleation centers are selected at the pelletizer bottom base, the dimensions of their ribs are measured, the degree of deformation of the nucleation centers is calculated and the angle of inclination of the bottom of the plate to the horizon is determined.

EFFECT: invention provides for the increased productivity of the pelletizer and for the increased strength of the pellets.

1 cl, 3 dwg, 1 tbl, 1 ex

Description

The invention relates to the field of ferrous metallurgy, namely the production of iron ore pellets.

A known method for producing pellets, including the formation of a skull on the bottom of the pelletizer, feeding a wet mixture into the pelletizer, cleaning the skull, nucleation, re-folding the seeds to pellets, the formation of a zone occupied by pellets on the pelletizer bottom and a zone free of pellets, heat treatment (pellet processing. I.E. Production of iron ore pellets, M .: Metallurgy, 1976, p. 82-92). The disadvantage of this method is the low productivity and strength of the pellets.

The closest in technical essence and the achieved result is a method for producing pellets, including the formation of a skull on the bottom of the pelletizer, inclined at an angle to the horizontal, the supply of a wet mixture into the pelletizer in two streams, the introduction of the first of them into a stream of compressed gas with the formation of a gas-liquid charge jet, formation on the bottom pelletizer of the zone occupied by the charge, and the zone free from the charge, the nucleation is carried out by spraying the charge with a gas-jet jet oriented to the skull, in the zone, free the bottom of the mixture, with obtaining a dense layer of wet mixture, dividing the aforementioned dense layer of wet mixture into seeds, cleaning the skull from the seeds with a rotating drum with ribs, rolling the seeds in the blank area of the pelletizer into the lower part of the pelletizer bottom, re-encapsulating the seeds with the charge of the second stream to pellet Patent No. 2356951, Russia, IPC 7, С22В 1/24, B. I. No. 15, publ. 27.05.2009).

The technical problem is that the rolling of the seeds in the idle zone of the pelletizer plate is carried out at a low speed, which leads to a decrease in pelletizer productivity and the strength of the pellets obtained. Another disadvantage of the known method for producing pellets is the difficulty of selecting the angle of inclination of the bottom of the plate to the horizon, since the degree of deformation of the nuclei during rolling and transportation in the blank area of the pelletizer to the lower part of the pelletizer is unknown. As it was established experimentally, the degree of deformation of the ribs and nuclei directly affects the angle of inclination of the bottom of the plate to the horizon. Moreover, the higher the degree of deformation of the embryo and its roundness, the smaller the embryo angle and, accordingly, the angle of inclination of the bottom of the plate to the horizon. As a result, the rolling conditions in the working area of the pelletizer change. The nuclei obtained from the sprayed charge layer are undeformed briquettes of regular cubic shape. If it is conditionally assumed that after the seeds are rolled in the idle area of the pelletizer into the lower part of the pelletizer bottom, it does not deform, then to ensure the rolling of the seeds of this shape on the plate bottom in the pelletizer working area, the angle of inclination of the plate bottom to the horizon should be at least 45 degrees. In the real process of rolling of the embryos in the empty area of the plate to the lower part of the bottom of the plate, the ribs of the embryos deform and become more rounded. As a result, the conditions of additional locking of the embryos to pellets in the rolling mode in the plate working zone are changed, and the angle of inclination of the plate bottom to the horizon decreases. It follows from this that in the idle and in the working zones the deformation conditions are different. The solution to the technical problem lies in the need to bring the deformation conditions in these zones closer to each other. To solve the technical problem, it is necessary to artificially organize the partial deformation of the embryos and their accelerated rolling in the idle zone of the pelletizer. Then you should calculate the degree of deformation of the embryos in this zone and calculate the angle of inclination of the bottom of the plate to the horizon. The adjusted value of the angle of inclination of the bottom of the plate to the horizon will ensure the operating mode of rolling the charge materials in the pelletizer with higher productivity and will allow to obtain pellets with higher strength.

,To solve a technical problem in the method of producing pellets, including the formation of a skull on the bottom of the pelletizer, tilted at an angle to the horizontal, the supply of a wet mixture into the pelletizer in two streams, the introduction of the first of them into the stream of compressed gas with the formation of a gas-liquid jet, the formation on the bottom of the pelletizer of a zone occupied charge, and the zone free of charge, nucleation, carried out by spraying the charge gas-jet jet, oriented to the skull, in the zone free of charge, with a dense layer wet charge, dividing the aforementioned dense layer of wet charge into embryos, cleaning the skull from the embryos with a rotating drum with ribs, rolling the embryos in the idle area of the pelletizer into the lower part of the pelletizer bottom, retrowing the embryos with the charge of the second flow to the pellets, rolling the embryos into the lower zone of the germinator in the idle zone pelletizer is carried out accelerated by means of a rotating drum with ribs, equipped with a drive, after which at the bottom of the bottom of the pelletizer are selected seeds in an amount of at least 10 pieces, measure the size of the ribs of each embryo, then calculate the degree of deformation of the embryos by the expression

,

Where

K is the degree of deformation of the embryos;

N is the number of seeds selected at the bottom of the pelletizer;

i is the number of ribs of the embryo, i = ... 12;

L _i is the length of the rib of the embryo, mm;

L is the initial length of the rib of the embryo after dividing the sprayed layer of the charge into embryos, mm;

and set the angle of inclination of the bottom of the plate to the horizon according to the formula γ = arctan (K),

Where

γ is the angle of inclination of the bottom of the plate to the horizon, degrees;

K is the degree of deformation of the embryos.

и задают откорректированное значение угла наклона днища тарели к горизонту по формуле γ=arctg (К).The invention consists in the following. In the course of nucleation and subsequent transportation of the embryos in the blank area of the plate to the lower part of the pelletizer, the embryos are rolled quickly by means of a rotating drum with ribs designed to clean the charge skull from the embryos. To do this, the rotating drum is equipped with a mechanical drive that allows you to quickly transport the embryos along the charge skull of the idler pelletizer zone to the lower part of the plate bottom, regardless of the mechanical work of the pelletizer. In the process of accelerated rolling of the embryos, their impact interaction occurs with each other, with the charge and onboard skull, partial deformation and hardening of the surface of the embryos. Due to these processes, pelletizing productivity and pellet strength are increased. Partially deformed nuclei with a more rounded shape can accelerate the processes of rolling and re-locking of nuclei in the working area of the pelletizer, which also contribute to increasing the productivity of the pelletizer. In order to ensure optimal conditions for the additional locking of deformed nuclei in the working area of the pelletizer and to assign the angle of inclination of the bottom of the plate to the horizon, a set of measuring measures is proposed in the process of implementing the method for producing pellets. To do this, at least 10 pieces of deformed embryos are selected at the bottom of the pelletizer bottom, the dimensions of 12 ribs of each embryo are measured, and then the degree of deformation of the entire selected lot of embryos is calculated by the expression

and set the adjusted value of the angle of inclination of the bottom of the plate to the horizon according to the formula γ = arctan (K).

The number of nuclei for measurements should be at least 10 pieces. In this case, the reliability of measurements and subsequent calculations of the quantities K and γ is ensured. If the number of nuclei is less than 10, then in this case the reliability of the obtained results decreases and the technical problem is not solved, since the angle γ can not be calculated accurately.

In this technical solution, it is proposed to adjust the value of the angle of inclination of the bottom rubbed to the horizon using measuring and computational measures. It is impossible to reduce the angle, since this will lead to a violation of the roll mode and the implementation of the method for producing pellets, which does not allow to solve the specified technical problem. An increase in the angle of inclination is technically possible, but requires the installation of additional reflective screens, changes in the moisture content of the charge, and a decrease in the frequency of rotation of the bottom of the plate, which is technically difficult and will lead to a decrease in the productivity of the pelletizer.

The distinctive features of the method for producing pellets, proposed in the claimed sequence, form new positive properties: the organization of hardening hardening of the surface of the seeds in the process of accelerated rolling of the seeds, thereby increasing the productivity of the pelletizer and the strength of the pellets; organization of simultaneously developing processes of partial deformation and hardening hardening; independence of the nucleation and rolling processes of nuclei in the idle zone of the pelletizer formed by acceleration the embryos with a rotating drum with ribs equipped with a drive from the angle of inclination of the bottom of the plate to the horizon; obtaining partially deformed nuclei in the idle zone of the pelletizer, allowing to accelerate the processes of rolling and retrowing of the nuclei in the working zone of the pelletizer; the convergence of the conditions of deformation of the embryos in the idle and in the working areas of the pelletizer bottom; assignment of the optimal value of the angle of inclination of the bottom of the plate to the horizon according to a new empirical expression obtained on the basis of new measuring and computational measures. The claimed parameters and new properties of the method for producing pellets can solve the specified technical problem and obtain pellets with higher strength and performance.

The method of producing pellets is implemented using the device shown in figure 1. Figure 2 shows the position of the undeformed seed after dividing the sprayed charge layer into seeds at the bottom of the pelletizer plate. Figure 3 shows a partially deformed embryo in the lower part of the bottom of the plate after accelerated rolling. The device comprises a disk pelletizer 1, into which a wet charge is supplied by stream 2 and stream 3. To form a gas-liquid charge jet 4, a jet device 5 is used. The jet device contains a compressed gas supply path 6. The pelletizer contains a bottom 7, a charge skull 8, a longitudinal divider 9, transverse a divider 10, designed to clean the charge skull from the seeds, made in the form of a rotating drum And equipped with ribs. The bottom of the pelletizer plate is tilted at an angle to the horizon (Figure 2). The rotating drum is equipped with a mechanical drive 12. In the process of pelletizing, a dense layer of the charge 13 is formed, which is divided by a longitudinal divider 9 into longitudinal charge strips. In the process of operation of the pelletizer on a dense layer of the charge 13 with a rotating drum 11 with ribs, transverse cuts are made and undeformed wet charge seeds 14 are formed. The work of the dividers 9 and 10 is aimed at obtaining the nuclei of the correct cubic shape with a given rib size L (figure 2). On the bottom of the pelletizer is formed a zone 15 free from crumpled materials, a zone 16 occupied by crumpled materials, and the lower part of the bottom of the pelletizer 17 to select partially deformed nuclei 18 with ribs L _i (figure 3).

The method of producing pellets is as follows. A wet charge is supplied to a disk pelletizer 1 by stream 2 and stream 3. To form a gas-liquid charge jet 4, a jet apparatus 5 is used, into the housing of which a charge of stream 2 and compressed gas supplied from path 6 are fed. To carry out the process of pelletizing the charge in the rolling mode the bottom 7 of the pelletizer plate is tilted at an angle to the horizon (figure 2). A charge skull 8 is formed on the bottom of the pelletizer 8. During operation of the device in zone 15, the jet apparatus 5 forms a gas-feed jet 4, which forms a dense layer of the charge 13. During rotation of the bottom of the pelletizer, the dense layer of the charge by the longitudinal divider 9 is divided into longitudinal charge strips, and the transverse the divider 10, made in the form of a rotating drum 11, equipped with ribs and a mechanical drive 12, forms undeformed nuclei 14. The design of the dividers 9 and 10 allows you to get undeformed nuclei pr villa cubic form with edges size L (Figure 2). The rotating drum 11, equipped with a mechanical drive 12, intensively cleans the charge skull from the embryos and rapidly rolls the embryos 14 to the lower part of the pelletizer bottom 17, where at least 10 pieces of partially deformed embryos 18 are selected (figure 1) for organizing measurement measures. The sizes of all 12 ribs are measured for each embryo (Figure 3), after which the degree of deformation K is calculated for the entire batch of embryos according to the above expression and the angle of inclination of the bottom of the plate to the horizon y is calculated. After that, the coordinate device of the pelletizer (not shown in the figures) sets the corrected angle γ of the inclination of the bottom of the plate to the horizon. Then the partially deformed embryos enter zone 16, where they are additionally rounded by the flow of the charge 3 to standard pellets. On existing equipment, adjusting the angle of inclination of the bottom of the plate can be done without stopping production.

Example. The development of the method for producing pellets was carried out on the installation, made according to the technical scheme shown in figure 1. In the working space of the pelletizer with a diameter of 0.62 m was loaded a wet mixture containing concentrate Teyskoye field and 1% bentonite as a binder. The mixture was loaded in two streams. The first charge stream in the amount of 4 kg was fed into the jet apparatus and sprayed with compressed air on the skull. The longitudinal divider and the ribs of the drum, designed to clean the skull from the seeds and accelerated rolling of the seeds, were made of 0.5 mm thick stainless steel. The drum length was 250 mm and its diameter was 60 mm. The drum was equipped with an electric drive with a frequency power regulator, necessary to control the frequency of rotation of the drum. The frequency of rotation of the drum was changed by changing the operating mode of the drive of the rotating drum and, thereby, the degree of deformation of the nuclei was regulated. In the lower part of the pelletizer bottom, at least 10 nuclei were taken in each experiment, in which the number of ribs and the sizes of each ribs were measured. After that, the degree of deformation of the embryos and the angle of inclination of the bottom of the plate to the horizon were calculated according to the above method. Then, the bottom of the plate was set at a corrected angle of inclination to the horizon, and a second charge flow of 6 kg was fed into the pelletizer working zone and the seeds were re-locked to conditional sizes. Compressed air was supplied from the compressor unit KU-22. Water supplied to moisten the embryos was sprayed with compressed air. At the end of post-compaction, the yield of standard pellets with a diameter of 14–16 mm was determined, from which pelletizer productivity was calculated, and the compressive strength of the pellets was measured. The experimental results are presented in the table.

As can be seen from the above data, the method for producing pellets based on the accelerated rolling of the seeds in the idler area of the pelletizer by a rotating drum with ribs equipped with a drive, selecting the seeds in the lower part of the pelletizer bottom, measuring the size of each seed, calculating the degree of deformation of the seeds and calculating the angle of inclination of the bottom of the plate to the horizon, it allows to increase the productivity of the pelletizer by 1.3-3.2% and the strength of the pellets by 2.1-10.5%.

Claims (8)

A method for producing pellets, including the formation of a skull on the bottom of the pelletizer, inclined at an angle to the horizontal, the supply of a wet mixture into the pelletizer in two streams, the introduction of the first of them into the compressed gas stream with the formation of a gas-liquid charge stream, the formation of the zone occupied by the charge and the zone on the pelletizer bottom free of charge, nucleation by spraying the charge with a gas-and-jet charge oriented to the skull in a zone free of charge, to obtain a dense layer of wet charge, dividing said a solid layer of wet charge onto the embryos, cleaning the scull of the embryos with a rotating drum with ribs, rolling the embryos in the idler zone of the pelletizer to the bottom of the pelletizer bottom, re-bridging the germ with a second flow charge to pellets, characterized in that the grazing of the germ in the idler zone of the pelletizer carry out accelerated by means of a rotating drum with ribs, equipped with a drive, after which at the bottom of the bottom of the pelletizer are selected nuclei in an amount of at least 10 pieces, measure the size ribs of the edges of each embryo, then the degree of deformation of the embryos is calculated by the expression

K is the degree of deformation of the embryos; N is the number of seeds selected at the bottom of the pelletizer; i is the number of ribs of the embryo, i = 1-12; L _i is the length of the rib of the embryo, mm; L is the initial length of the rib of the embryo after dividing the sprayed layer of the charge into embryos, mm; and set the angle of inclination of the bottom of the plate to the horizon according to the formula γ = arctan (K), deg.

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