RU2673588C1 - Method of making pellets - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy, specifically to production of iron-ore pellets. Wet mixture is fed into the pelletizer in two streams and the formation of a skull on the bottom of the pelletizer, inclined at an angle to the horizon. 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. Zone occupied by the charge consists of an ascending layer and a descending layer of materials. 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. Perform the division of the above-mentioned dense layer of the wet mixture into nucleation centers with rib length L, cleaning the skull from nucleation centers by a rotating drum with ribs. Carry out complete pelletization of nucleation centers with the second stream charge to the pellets. Resulting nucleation centers are divided into streams with a width of (2–6)L and oriented with curvilinear guides to the area occupied by the charge. Stream of compressed gas is fed to each stream by means of which the nucleation centers are transported to the descending layer of materials and evenly distribute them over the cross section of the specified layer.

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

1 cl, 1 dwg, 1 tbl

Description

The invention relates to the field of ferrous metallurgy, namely, to 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, consisting of an ascending layer and a descending layer of materials, and a zone free of charge, nucleation by spraying a gas mixture a goshicht jet oriented to the skull in a free zone of a charge to obtain a dense layer of a wet charge, dividing the said dense layer of a wet charge into seeds, cleaning the skull from the seeds with a rotating drum with ribs, rolling the seeds in the blank area of the pelletizer to the bottom of the pelletizer bottom , retrowing the embryos with the charge of the second stream to pellets in the zone occupied by the charge (see Patent No. 2356951, Russian Federation, IPC 7, С22В 1/24, B.I. No. 15, publ. 05/27/2009).

The technical problem is that in the process of rolling the embryos in the blank area of the plate to the lower part of the pelletizer bottom and their subsequent transportation in the ascending layer of materials to the upper point of the vertical diameter of the plate, there is no increase in mass and the formation of the shell of the pellets. The durations of these idle processes are quite high. If we take the duration of the formation of pellets as 100%, then the duration of rolling the embryos in the idle zone and transporting them in the ascending layer of materials is about 30-40% of the working time. The working process of pelletizing by rolling embryos starts from the upper point of the vertical diameter of the plate in the descending layer of materials and is 60-70%. of the entire duration of the workflow. The disadvantage of this method is that in the process of rolling the embryos in the idle zone of the plate to the lower part of the pelletizer bottom, a certain amount of fines is formed from the destruction of the corners of the embryos, which forms a skull and does not participate in the pelletizing process, reducing the pelletizer productivity. The solution to the technical problem lies in the need to reduce the length of the idle path of motion of the embryos in the charge-free zone and the duration of the motion of the embryos in the ascending layer of materials to the point of the onset of rolling. To solve the technical problem, it is necessary immediately after nucleation to arrange the transportation of the embryos by the shortest route to the plate zone occupied by materials, and to ensure the rolling process with minimal loss of working time. The resulting charge charge should also be involved in the process of pelletizing without loss of working time. In this case, during transportation, it is necessary to ensure uniform distribution of the nuclei across the width of the descending layer of materials. As a result of reducing the loss of working time, the production mode of rolling of the seeds in the pelletizer is implemented 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 of a zone occupied on the pelletizer 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 with a rib length L, cleaning the skull from the embryos with a rotating drum with ribs, retrowing the embryos with a second stream charge to pellets, according to the invention, after nucleation, the nuclei are divided into streams of width (2-6) L using curved guides, and orient them to the area occupied by the charge, and a stream of compressed gas is brought to each stream, with the help of which the nuclei are transported to the descending layer of materials and evenly distribute them over the cross section ju specified layer.

The invention consists in the following. After nucleation, the nuclei formed are divided into separate streams of width (2-6) L with the help of curved guides, which at one end (vertically oriented) are adjacent to the rotating drum and the other end (horizontally located) are oriented perpendicular to the zone occupied by the charge. Moreover, for each stream of embryos, which, under the influence of their own weight, are poured into the gap between adjacent horizontally arranged parts of the guides, a stream of compressed gas is supplied. Using the energy of compressed gas, the nuclei are transported along the shortest path to the descending layer of materials and are evenly distributed over the cross section of the specified layer. Curved guides are made of elastic materials to provide soft (non-destructive) rolling of the embryos along their surface. During transportation, the angles of the embryos are deformed and primary hardening occurs. The jets of compressed gas are supplied to the streams at different distances from the boundary of the descending layer. Therefore, the embryonic streams closest to the border of the descending layer are transported to a farther distance and are stacked in the most remote section of the descending layer. The nuclei located further from the boundary of the descending layer of pellets are stacked in the near section of the layer. This arrangement of the jets of compressed gas allows you to evenly distribute the nuclei over the cross section of the descending layer of materials. The process of uniform distribution of nuclei over the cross section of the layer can be further controlled visually by changing the flow rate of compressed gas using shutoff valves. Once in the flow of rolling materials, the embryos immediately participate in the rolling process and, without loss of time, begin to form the shell of the pellets.

After nucleation, the nuclei must be divided using curvilinear guides into streams of width (2-6) L. In this case, a stable process of transporting the nuclei to the downward layer of materials is ensured and an increase in pelletizing productivity and pellet strength is achieved. If the width of the streams is less than 2 L, then in this case jamming of the seeds in narrow curvilinear gaps of the guides and violation of their transportation to the downward layer of materials is possible, which leads to a decrease in the productivity of the device. At the same time, the number of nozzles and jets increases, which complicates the design of the device and contradicts the objective of the invention. If the width of the streams is more than 6 L, then in this case the mass of the nuclei in each stream increases significantly and for transporting the nuclei, high-power jets will be required, which can lead to the destruction of the nuclei during transportation and decrease the strength of the pellets and the performance of the device.

The technical effect consists in the fact that the distinguishing features of the invention proposed in the claimed sequence form new positive properties: organization of hardening hardening of the surface of the embryos on the surface of the elastic guides in the process of accelerated rolling of the embryos; reduction of loss of charge fines with the formation of a skull and its participation in the pelletizing process; reducing the length of the idle path of motion of the embryos to the working zone of the roll in the downward layer of materials; uniform distribution of nuclei over the cross section of the descending layer of materials, thereby increasing the productivity of the pelletizer and the strength of the pellets. 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.

A method of producing pellets is implemented using the device shown in the figure. The device comprises a disk-shaped 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 has 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 11, equipped with ribs. The bottom of the pelletizer plate is tilted at an angle to the horizon. In the process of pelletizing, a dense layer of the charge 12 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 12, transverse cuts are made with ribs 11 with ribs and moist charge seeds 13 are formed. In the process of operation of the device, a zone 14 free from crumpled materials is formed on the bottom of the pelletizer, zone 15 occupied by crumpled materials. The zone occupied by materials consists of an ascending layer of materials 16 and a descending layer of materials 17. To divide the embryos 13 into separate streams (not indicated in the figure) and then orient them to zone 15, the device contains curved guides 18 that are rigidly fixed to the bottom of the plate with a gap to the surface of the skull (mounting guides on the figure is not shown). Curved guides 18 have a vertical section in which the nuclei move under the action of their own weight, and a horizontal section for transporting the nuclei along which jets of compressed gas are intended. For the formation of jets are nozzles 19, which are supplied with compressed gas from the path 6. To control the flow of compressed air nozzles are equipped with control equipment. During the operation of the device, finished pellets of 20 standard sizes are formed.

The method of producing pellets is as follows. A wet charge is supplied to the disk pelletizer 1 by stream 2 and stream 3. A charge of stream 2 and compressed gas supplied from tract 6 are fed into the housing of the jet apparatus 5. During operation, a charge skull 8 is formed on the bottom of the pelletizer 8. On the charge skull using a jet apparatus 5, a gas and gas charge jet 4 is formed, which in zone 14 forms a dense layer of the charge 12. During rotation of the pelletizer bottom, the dense layer of the charge by the longitudinal divider 9 is divided into longitudinal charge strips. The transverse divider 10, made in the form of a rotating drum 11, equipped with ribs and a mechanical drive 12, forms the nuclei 13. The design of the dividers 9 and 10 allow to obtain nuclei of the correct cubic shape with the size of the ribs L. The embryos 13 are divided into separate streams with a width of (2-6) L the vertical section of the guides 18, in which the nuclei move under the action of their own weight to the horizontal section, the transportation of the nuclei along which is carried out by the energy of the jets of compressed gas. The jets are formed using nozzles 19, into which compressed gas is supplied from the path 6. Regulation of the flow of compressed air through the nozzles is carried out by control equipment. Regulation of the flow rate and energy of the jets is necessary for uniform distribution of the nuclei over the cross section of the descending layer 17. After the nuclei are transported to the surface of the descending layer, they fall into the layer of moving materials and begin to gain mass and form the shell of the pellets in the rolling mode, rolling down to the bottom of the plate bottom. Then, the finished pellets 20 enter the surface of the ascending layer of materials 16, after which they are unloaded from the plate onto the conveyor belt.

Example. The development of the method for producing pellets was carried out on the installation made according to the technical scheme presented in the figure. A wet charge containing concentrate from the Teyskoye deposit and 1% bentonite as a binder was loaded into the pelletizer working space with a diameter of 0.62 m. 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 to obtain nuclei. The second charge stream in the amount of 6 kg was fed into the working area of the pelletizer for additional locking of the embryos. The longitudinal divider and the ribs of the drum designed to clean the skull from the seeds were made of 0.5 mm thick stainless steel. The drum length was 250 mm and its diameter was 60 mm. Curved guides were made of soft rubber with a thickness of 5 mm, which were profiled using a metal frame that allows you to change the width of the streams of nuclei. Compressed air was supplied from the compressor unit KU-22. Part of the air was fed into the formation of an air-charge jet, another part of the air was sent to transport the nuclei to the descending layer of materials through the guides. Water supplied to moisten the embryos was sprayed with compressed air. The uniform distribution of the embryos over the cross section of the descending layer was carried out during visual observation of the process using compressed air control valves. 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, a method for producing pellets based on dividing the embryos into streams of width (2-6) L using curved guides and orienting them to the zone occupied by the charge, using jets of compressed gas and their uniform distribution over the cross section of the specified layer, allows to increase the productivity of the pelletizer by 3.4-7.1% and the strength of the pellets by 2.1-10.5%.

Claims (1)

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 on the pelletizer bottom of a zone occupied by a charge consisting of an ascending layer and a descending layer of materials, and the zone free of charge, nucleation, carried out by spraying the mixture with a gas-liquid jet oriented to the skull, in the zone free of charge, with by treating a dense layer of a wet mixture, dividing said dense layer of a wet mixture into embryos with a rib length L, cleaning the skull from the embryos with a rotating drum with ribs, retrowing the nuclei with a second stream charge to pellets, characterized in that after nucleation, the nuclei are divided into brooks with a width of 2 ( 6) L and orient with the help of curved guides to the zone occupied by the charge, and a stream of compressed gas is brought to each stream, with the help of which the nuclei are transported to the descending layer of materials and uniformly distributed distribute them over the cross section of the specified layer.

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