RU2278172C1 - Batch preparation for sintering - Google Patents

Abstract

FIELD: ferrous metallurgy, in particular production of iron-ore pellet.

SUBSTANCE: damp batch is fed into pelleter in form of two streams. The first of one is introduced into stream of compressed gas to form gas-moisture-batch jet; followed by batch sputtering, nucleation, finished balling with batch of the second stream to obtain target pellet. Nucleation is carried out by batch sputtering on rolled cylindrical drums to produce dense layer of damp batch on the surface thereof. Before batch sputtering gas-moisture-batch jet is divided to separate jets, then dense layer of damp batch is separated from drum surface to produce pellet in form of damp batch briquettes, which are finished balled to conditional pellet.

EFFECT: pellet of increased strength.

1 dwg, 1 tbl, 1 ex

Description

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

A known method of preparing the mixture for sintering, including the supply of a wet mixture into a pelletizer, nucleation, re-assembly of the embryos to obtain pellets (see I. Ruchkin, Production of iron ore pellets. M: Metallurgy, 1976, p. 82-92). The disadvantage of this method is the low strength of the pellets.

The closest in technical essence and the achieved result is a method of preparing the mixture for sintering, which includes feeding the wet mixture into the pelletizer in two streams, introducing the first of them into the compressed gas stream with the formation of a gas-liquid charge jet, spraying the mixture, nucleation, re-encapsulating the nuclei with a second stream charge to obtain pellets (see Patent No. 2232823, Russia, IPC 7 C 22 V 1/24, B.I. No. 20, 2004). The disadvantage of this method is the low strength of the pellets obtained from hard-to-assemble charge materials. It is due to the low efficiency of nucleation, pelletizing, and hardening of crumpled materials. Hard-burden blends include coarse-grained burden, sinter charge, materials containing fuel and hard-to-break additives. The intensification of nucleation in the process of pelletizing with obtaining strong nuclei in the form of charge briquettes allows to increase the productivity of the pelletizer and the strength of the pellets.

The objective of the invention is to increase the strength of the pellets.

To achieve the specified technical result in the method of preparing the mixture for sintering, which includes feeding the wet mixture into the pelletizer in two streams, introducing the first of them into the compressed gas stream with the formation of a gas-liquid charge jet, spraying the mixture, nucleation, re-locking the nuclei with the charge of the second stream to pellets, nucleation is carried out at feeding the mixture by spraying it onto rotating cylindrical drums to obtain a dense layer of a wet mixture on their surface, moreover, before spraying the mixture The feed stream is divided into separate streams, after which the surface of the drums is cleaned of a dense charge layer with the formation of nuclei in the form of wet charge briquettes.

The invention consists in the following. The nucleation process for difficult-to-charge blends is organized using the forceful action of a compressed air jet on the wet charge of the first stream. To do this, a gas and gas charge stream is formed, which sprays a wet charge on rotating drums and creates the pressure on their surface necessary for the formation of a dense layer of a wet charge. The density of the wet charge layer is close to the density of raw pellets. The gas-moisture-spray jet is a forming tool for a wet charge, which is sprayed in the form of a dense corrugated layer on the surface of cylindrical drums. The processes of charge deposition and nucleation are carried out on a single section of the technological chain - on the section where the mixture is fed into the pelletizer, where in normal production there are no technological operations. In this case, the working space of the pelletizer is used more rationally. To organize nucleation, a jet divider and rotating cylindrical drums are installed between the jet apparatus forming the jet and the clumping layer of materials. The gas-water-jet stream in a few seconds of spraying the mixture onto the drums compacts the mixture to the density of raw pellets. The rate of charge deposition (nucleation) and hardening of the charge layer exceeds by more than an order of magnitude the similar parameters for pelletizing the charge by the traditional rolling method. Accelerated by the flow of compressed air and sharply braked by cylindrical drums, the wet mixture is quickly compacted and transformed into a strong layer of the mixture, which is the basis for the formation of nuclei formed in the form of briquettes. To obtain embryos (solid briquettes in the form of small hemispheres or pillows of arbitrary shape 3-10 mm in size) from the sprayed layer of the charge, the gas-liquid charge is divided into separate jets before spraying the mixture. For this, a divider is installed between the jet apparatus and cylindrical drums on the path of the gas and gas jet distribution. The divider is a grating with round or square channels. Wet charge flows through the channels of the divider to the surface of cylindrical drums in a dosed form. When a charge is sprayed in the form of many separate charge streams on cylindrical drums, a dense corrugated charge layer of a variable height is formed, consisting of many elevations (briquettes) separated by charge grooved channels. The channels are represented by a compacted charge of a minimum height of 0.5-2.0 mm. After spraying, the briquettes have weak bonds between themselves and the surface of the drums. To separate the dense layer of the mixture, consisting of briquettes and grooved channels, from cylindrical drums with the formation of separate (unrelated) briquettes, a mechanical separator is used. It simultaneously serves as a drum cleaner from the remnants of a dense layer. For the consistent execution of all technological operations, cylindrical drums must rotate at a certain speed. The rotation of the drums is carried out by the gas and moisture charge jet itself, transferring part of the energy to the drums for rotation. The rotational speed of the drums is regulated by a cleaner, which allows you to change the force of pressing its working body to the surface of the drum. In the proposed technical solution, a mechanical drive of cylindrical drums is possible if the jet power is not enough for their rotation or the number of drums is more than three.

For efficient nucleation, a gas-fluid stream should spray a mixture onto at least two cylindrical drums. This scheme provides the maximum spraying surface and the possibility of rotation of the drums. After separating the briquettes from the rotating cylindrical drums, the resulting briquettes in the free fall mode enter the pelletizer working space, where, playing the role of the embryos, they are re-locked to the conditional pellets with a second stream charge. The process of producing pellets according to the scheme: spraying the mixture with the formation of embryos in the form of wet charge briquettes and additional pelletizing in the working space of the pelletizer is characterized by high productivity and hardening speed. The resulting pellets have a higher strength compared to pellets pelletized according to the traditional rolling scheme of materials.

In known methods of briquetting, briquettes are obtained by compressing the mixture in a narrow contact zone between two rotating drums equipped with a mechanical drive, on the surface of which molds are made in the form of hemispheres. If molds of a more complex shape are used, then briquettes are obtained in the form of small pillows with a complex profile. In the proposed technical solution, there are no molds, and cylindrical drums have a smooth surface, which is the basis for molding (spraying) the mixture and obtaining briquettes (seeds). Moreover, the surface of the drums, on which the formation of briquettes, is significantly higher than in the known method. The optimal force required for the formation of durable briquettes creates a high-pressure gas and moisture spray jet. It is possible to regulate the jet pressure by simple methods: the pressure of compressed air, the ratio of the flow rates of compressed air and the charge, by changing the distance between the nozzle exit of the jet apparatus and the drums, and the location of the jet divider relative to the drums. The technological scheme of spraying (briquetting) the mixture is simple, small dimensions of the apparatus and the lack of an electric drive.

Thus, due to distinctive features from the prototype, the claimed method acquires new properties: the formation of a dense corrugated layer of the mixture by spraying the wet mixture with a gas and liquid jet; nucleation is carried out by the method of spraying the mixture onto rotating cylindrical drums; transformation of wet loose mixture into a dense corrugated layer, represented by a continuous ribbon of charge briquettes connected by grooved channels; organization of rotation of the drums by a jet; combination of drum cleaning operations and separation of briquettes from their surface, which together can improve pelletizing performance and pellet strength.

The method of preparing the mixture for sintering is implemented using the device shown in the drawing.

The device comprises a pelletizer 1, into which a wet charge is supplied by stream 2 and stream 3. To form a gas and gas charge jet 4, a jet device 5 is installed in the pelletizer working space 5. The jet device comprises a housing 6 and a compressed air supply path 7. Rotating cylindrical drums 8 are installed between the jet apparatus and the pelletizer fences (disk bottom or drum walls) 8. The gas divider jet divider 9 is located between the jet apparatus and cylindrical drums. On the surface of the cylindrical drums, a continuous corrugated layer 10 of the wet charge is formed. To separate the dense layer of the charge from the surface of the cylindrical drums, the device is equipped with separators 11. In the process of separating the dense layer of the mixture and cleaning the cylindrical drums from the remnants of the material, the dense corrugated layer is destroyed into separate fragments, which are briquettes 12.

The method of preparing the mixture for sintering is as follows. The wet charge is fed into the working space of pelletizer 1 by flows 2 and 3. The wet charge stream 2 is involved in the nucleation and spraying of the wet charge on the rotating drums. For this, the flow of the charge 2 is directed to the housing 6 of the jet apparatus 5, where it is accelerated by compressed air supplied through the path 7. At the outlet of the jet apparatus 5, a gas-moisture charge 4 is formed, which sputters the wet charge on the surface of the cylindrical drums 8 and forms a dense continuous corrugated layer 10 wet charge. In order for the dense layer 10 to be formed in the form of briquettes interconnected by grooved bridges of the charge, a divider 9 is installed at the boundaries (determined by the opening angle) of the jet 4. The divider 9 is a system of individual channels through which the wet charge is dosed to the surface of the drums 8. The continuity of the process of spraying the mixture onto cylindrical drums 8 is ensured by their rotation due to the dynamic pressure of the gas-liquid charge jets leaving the divider 9. In order to obtain a wet mixture from the continuous layer 10 l briquettes playing the role of nuclei in the process of pelletizing, the drums 8 are equipped with a separator 11. The separators 11 act as a cleaner (knife), separating the layer 10 from the surface of the drums 8 and destroying it into briquettes 12. The destruction of the layer 10 occurs along the borders (grooved channels) of the briquettes which in the free fall mode enter the layer of moist clumping materials formed by the stream 3 of the wet mixture. Briquettes 12 are nuclei (pelletizing centers) of high strength, onto which a wet mixture is easily rolled and strong pellets quickly grow.

Example. The development of the method of preparing the mixture for sintering was carried out on a disk pelletizer with a diameter of 0.62 m, into the working space of which 10 kg of a wet mixture containing concentrate of the Teysk deposit and 1% bentonite was loaded. The technology of deposition and nucleation of the mixture was organized according to the scheme shown in the drawing. Steel cylindrical drums with a diameter of 100 mm and a length of 200 mm, the axis of rotation of which made an angle of 90 ° with the axis of the jet apparatus, were used as the basis for spraying the charge. The gas and gas jet divider is made of steel tubes with a diameter of 10 mm and a length of 50 mm. In the experiments, the flow rate of the charge supplied to the housing of the jet apparatus for spraying onto cylindrical drums was changed. The relative consumption of the sprayed charge (referred to the entire mass of material) was calculated. After the pelletizing of the charge was completed, the fractional composition of the crumpled materials, the yield of conditioned pellets, and their compressive strength were determined. The experimental results are presented in the table.

Table No. p.p. Relative charge consumption directed to nucleation, fractions of units The strength of the pellets, N / pellet The output of pellets with a diameter of 10-15 mm,% (abs.) one 0.25 12.6 21.1 2 0.50 12,2 24.4 3 0.75 10.1 28.8 Prototype Data four - 9.2 19.0

As can be seen from the above data, the method of preparing the mixture for sintering, based on nucleation by spraying a wet mixture onto rotating cylindrical drums, allows to increase the strength of raw pellets by 9.8-36.1% (rel.) And increase the yield of conditioned pellets by 11, 1-51.5% (rel.).

Claims (1)

A method of preparing a charge for sintering, comprising supplying a wet mixture to the pelletizer in two streams, introducing the first of them into a compressed gas stream with the formation of a gas-liquid charge jet, spraying the mixture, nucleation, re-encapsulating the nuclei with a charge of the second stream to pellets, characterized in that the nucleation is carried out when feeding the mixture by spraying it on rotating cylindrical drums with obtaining on their surface a dense layer of a wet mixture, and before spraying the mixture, the gas-liquid jet is divided into separate jets, after which they separate the dense layer of the charge from the surface of the cylindrical drums with the formation of nuclei in the form of wet charge briquettes.