SU1452854A1 - Method of producing pellets - Google Patents

Abstract

The invention is intended for the production of pellets. The aim of the invention is to increase the strength of the pellet and the performance of the method. The method includes loading the charge into a sealed pelletizer, moistening and pelletizing under pressure, classifying the pellets into a finished and circulating product, feeding the latter through the circulation path to the pelletizer, drying and roasting. The circulating product is discharged from the pelletizer into the sealed circulation path through the sealed intermediate chamber at a pressure differential between the working space of the pelletizer and the intermediate chamber equal to 4.0-9.5 kPa. 2 ill., 1 tab.

Description

ate 1C

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The invention relates to ferrous and nonferrous metallurgy and can be used in the production of pellets from finely divided materials,

The purpose of the invention is to increase the strength of pellets and productivity

way.

The essence of the method lies in the fact that all technological operations for obtaining raw pellets are carried out in sealed apparatus of a closed circulation loop: pelletizer, classifier, intermediate chamber and circulation path of the product. Moreover, they all constitute a closed system, since in the circuit there are operations proceeding under different pressure (vacuum) and associated with the movement of the pressure medium.

The peculiarity of the method for producing pellets is that pelletizing can be carried out at any excess pressure, including atmospheric pressure, while the classification can also occur at excessive, atmospheric pressure and rarefaction, but the presence of differential pressure in the pelletizer is necessary. and an intermediate chamber in the range of 4.0-9.5 kPa.

The need for the proposed processes is dictated by the following considerations. The pelletizing of raw bulk materials under pressure (lime process) is characterized by an intensive yield of conditioned granules. This means that embryos, granules and conditioned pellets with a minimum amount of bulk material are formed already in the initial area of the pelletizer. In the unloading area of the pelletizer (mainly drum), there is a significant segregation of pellets by size, so their classification is necessary with the allocation of suitable pellets (fraction +12 mm), as a result of which a circulating product (fraction 12 mm) is formed, going to the second docking. drum drummer.

In the process of classification of materials and the removal of finished materials from the working area of the pelletizer (by the known method), there is an intense barodiffusion of moisture removal, but in this case there is a danger of a decrease in strength as ready.

as well as the circulating product, with sharply expanded gas.

In order to eliminate the noted deficiencies, it is necessary at the time of the pellets to suck off the gas in the pores of the pellet, and at the same time affect it with the static and dynamic pressure of the working medium. As a result of these operations, the softening effect of the gas escaping from the pores of the pellet decreases, and as the pores have less pressure (vacuum), and the surface of the pellet undergoes more static and dynamic pressure of the working medium, the shrinkage of the raw pellet will occur and strengths According to this mechanism, conditional pellets and undercomplete embryos are strengthened, from which durable pellets are obtained after post-drilling.

This results in some compaction of the pellets associated with an increase in the pressing force from the octopus to the surface of the pelletizing drum, and the pouring layer rises to a great height, goes a long way of pelletizing and enhances the dynamic compaction of the pellets and embryos with an intensively moving layer of material.

The result of the proposed actions is an increase in the strength of the raw granules, an effective hydrodynamic removal of moisture from the pores and an increase in the productivity of the method. The circulating product is supplied from the pelletizer working space through the classifier to the sealed path through the sealed intermediate chamber, while the work is carried out under pressure, the internal surface of the classifier is under. large pressure, the outer surface of the classifier - under less pressure (vacuum). The pressure drop provides effective compaction of the moving on the inclined surface of the pellet, creates conditions for intensive barodiffusion moisture removal both from the depth and from the surface of the pellet, contributes to the transport of circulating load and accelerates the nucleation in the forger due to movement of the gaseous flux in the working space pelletizer

which is a better way to do this.

In the traditional (existing) technology, the circulation product, after being classified using belt conveyors, is overloaded in a rather complicated way to the charging section of the pelletizer. However, it is possible to transport the octapes of the -12 mm fraction by pneumatic transport. It has high performance, relative simplicity and low cost.

The possibility of pneumatic transport of raw pellets is explained by the high strength of the pellets of the circulating product obtained in the pelletor under pressure. Moreover, the pellets can be transported at a sufficiently high speed (up to 2.0 m / s) without the risk of their destruction.

Fig. 1 is a schematic diagram for implementing the method of pelletizing bulk materials under pressure; figure 2 - section aa on

figure 1.

The method is carried out using a device that contains a conveyor 1, which is needed to supply a slightly wetted charge 2 through a loading device 3 made in the form of conical closures combined with a guide tray 4. Drum pelletizer 5 has a path 6 for supplying water to humidification and a classifier 7 , to which a sealed intermediate chamber 8 adjoins the outer side of the pellet 5.

At the end of the drum pelletizer 5, an unloading device 9 is made, through which the finished (conditional pellets fr. +12 mm) granules 10 are unloaded onto the conveyor 11, which feeds them to the drying and calcining zone of the conveyor machine.

Circulating product 12, obtained by classifying materials, enters the circulating sealed path 13, in which an air (steam) compressor or injector 14 is arranged in the case of classification under vacuum (in this case, the role of the intermediate chamber 8 is performed by a vacuum chamber ).

The outlet section 15 of the circulation path 13 is combined with a feeder, which serve to jointly feed

five

the charge and the circulating product into the initial part of the drum pelletizer 5. Geometry of the working space of the pelletizer 5 and the circulation path 13 is carried out using end seals 16 and seals 17.

The method is carried out as follows.

Conveyor 1 moistened charge 2 is fed to the loading device 3, which is a system of sluice gates, which successively lower, direct the charge through feeder 4 to the drum pelletizer 5.

As a result of the rotation of the pelletizer 5, the charge 2 pelletizes with the addition of additional moisture through the path 6. In the discharge part of the pelletizer 5, the classifier 7 is arranged to separate the suitable product (fr. +12 mm) from the non-conforming granules (fr. -12 mm). in the form of a drum grate or slit screen. To create a pressure differential at the grate level of the classifier 7, a pressurized intermediate chamber 8 adjoins the outer surface of the pelletizer 5. The finished product enters the discharge device 9, after which the finished pellets 10 are placed on the conveyor 11 and fed to the roasting unit.

Circulating product 12 under the action of the weight of the granules and the pressure differential enters the sealed circulation path 13, in which the jet air injector 14 is installed. Moreover, when the injector 14 is operated, a lower pressure (vacuum) is created in the inlet section 13, and in the inlet section 15 by means of which the circulating product is fed to the post-cocooning, a greater pressure (pressure) is created. Therefore, the transportation of the circulating product 12 also occurs under pressure.

As the working medium of the injector 14, pressurized water but steam may be used. In this case, the moistening operation is performed by a water vapor condensate.

For more efficient pelletizing of the charge 2 and post-compaction of the circulating product 12, the output section 15 and the feeder 4 are placed flush with each other, in order to seal the entire technological circuit of the apparatus, mechanical seals 16 and seals 17 are provided. Al adjusting the differential pressure U5285A6

loads use industrial air compressor. Compressed air with pressure o 0.4 MPa is used as a gaseous energy carrier.

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Scientific research institute

The pick-up device 5 and the intermediate chamber 8 are equipped with an adjustment valve 18, which, if necessary, is operated for discharge or discharge.

With

between workspace

the implementation of the method in the hospital with a mobile compressor unit (0.25 m / min). The jet compressor is installed in the circulation path so that the suction nozzle

1Q combined with an intermediate chamber.

The loading of the SILCH is carried out with tanks weighing 1 kg, humidity 10.5%. After that, the digger and compressor are put into operation, and the casting time 15 NIN 10 min. After completing the process, the strength of the conditioning pellets (fractions +12 mm), their yield, the amount of the circulating product, and the moisture content of the pellets after drying are determined.

With continuous operation and continuous operation, the pressure drop during the operation of an air compressor or an injector is ensured by the natural loss of compressed air through the loading 3 and the discharge 9 of the pelletizer 5.

1 p and meer. Investigation okomko- 2o Specific fuel consumption. Iron ore concentrate van In this work, the value of pressure is changed on a laboratory drum in the circulation path, in a work pellet with a diameter of 0.3 m. than in the pelletizer, in a pro. The work space of the pelletizer is provided in the interstitial chamber, which is sealed with a metal seal. pressures between working breakers with rubber pelletizer and intermediate spacers. In the discharge chamber of the Noah. Differential pressure regulating the pelletizer is performed by classifying with compressed air flow in the form of slots 12x60 in size, located. Measurement of differential in chess order. Pressure is carried out by the Differential Intermediate Chamber, circulating

ny path and seals are made of rubberized conveyor

.

To create a pressure differential on the grate of the classifier and

-g - ---

transporting circulation

micromanometer, the output ends of which are connected to impulse tubes. The value of the differential pressure significantly affects the performance of the process and the quality of the process. 35 The research results are summarized in the table.

Note. A dash corresponds to the difficulty of classification.

and the implementation of the method of obtaining it.

The optimum pressure differential between the pelletizing medium and the vacuum zone is an interval of 4.0-9.5 kPa.

The specified differential pressure interval and the operation of the ejector lead to intensive barodiffusion / removal of 0.3-1.1% moisture. During the subsequent drying of pellets of low moisture content at the roasting unit, it saves up to 0.5-1.9% of thermal energy. The optimum pressure differential interval ensures the movement of raw pellets along the circulation path at a speed of 1.5-2.0 m / s. : claims

The method of obtaining pellets, including the loading of the charge in the working process

548

pressurized pelletizer space, moistening and pelletizing under pressure, classification of pellets into finished and circulating product, feeding of the latter through the circulation path into pelletizer, drying and roasting, characterized in that, in order to increase the strength of the pellets and the performance of the process, the feed of circulating product From the working space of the pelletizer, they are carried out into a sealed circulation path through a sealed intermediate chamber with a pressure differential between the working space komkovatel and the intermediate chamber, 4,0- equal to 9.5 kPa.

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Claims (1)

Claim A method for producing pellets, including loading the charge into the working space of a sealed pelletizer, humidification and pelletizing under pressure, classifying the pellets into finished and circulating products ⁵ , feeding the latter through a circulation path to the pelletizer, drying and firing, characterized in that, for the purpose of increase the durable ₁₀ ty of pellets and the productivity of the method, the supply of the circulating product from the working space of the pelletizer is carried out in a sealed circulation path through a sealed intermediate an exact chamber at a pressure differential between the working space of the pelletizer and the intermediate chamber equal to 4.09.5 kPa. For heat treatment