RU2465349C1 - Agglomerated charge sintering method - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: iron-containing part of charge, solid fuel, fluxing additions and reject is dosed, mixed, pelletised and charged in two layers to sintering trolleys. Then, charge is ignited by creating the negative pressure under sintering trolleys. Solid fuel is dosed in the form of small-sized coke by its introduction to the charge of upper and lower layers with fraction content of less than 0.5 mm in solid fuel of 15-25% and 35-45% respectively.

EFFECT: increasing specific output of agglomeration plant and improving mechanical properties of finished agglomerate.

1 ex, 1 tbl

Description

The invention relates to ferrous metallurgy, and more particularly to sintering processes of fluxed sinter for blast furnace smelting of cast iron.

A known method of supplying fuel to the sinter charge, comprising autonomous dosing of solid fuel in the housing of the charge silos and the sinter body; the fuel content in the upper layer is 1% higher (abs.) than in the lower one (see Steel, 1974, No. 10, pp. 876-878).

The disadvantage of this method is the over consumption of solid fuel due to insufficient use of the reactivity of fuel of various sizes.

The closest in technical essence is the method of sintering the sinter mixture, which provides for the separation of solid fuel into fractions, moreover, in order to increase the performance of the unit, fuel of a fraction of more than 0.5 mm is introduced into the upper layer of the charge, and fraction fuel of less than 0.5 mm is introduced into the lower layer ( see USSR AS No. 290039, IPC C21B 1/10, BI No. 2, 1971). In addition, it is envisaged to introduce a mixture of fuels into the lower charge layer, the fraction content of which is less than 0.5 mm, which amounts to 2/3 of its total content in the mixture in the lower layer.

The disadvantage of this method is the low specific productivity of the sinter plant, the reduced mechanical strength of the sinter when used in the charge of fuel production composition.

These disadvantages of the known method are explained by an increase in the fraction content of more than 3 mm to 20% in the solid fuel of the upper layer due to a significant increase in the number of liquid phases, which lead to an increase in the gas-dynamic resistance of the combustion layer and a corresponding decrease in the sintering speed of the agglomeration layer. The implementation of the known method in agglomeration factories is complicated by the lack of classifying equipment that operates with high productivity and allows you to effectively sift a fraction of less than 0.5 mm from the fuel of the upper layer.

The objective of the invention is to increase the specific productivity of the sinter plant and increase the mechanical properties of the finished sinter.

The specified technical result is achieved by implementing the method of sintering the sinter charge, including dosing the iron-containing part of the charge, solid fuel, fluxing additives, return, mixing the charge, pelletizing the charge, two-layer loading of the sinter charge on the sintering trolleys, subsequent ignition of the charge, creating a vacuum under the sintering trolleys, this dosing of solid fuel in the form of coke breeze is carried out by introducing it into the charge of the upper and lower layers with a fraction of less than 0.5 mm in solid fuel 15-25% and 35-45%, respectively.

The increase in the specific productivity of the sinter plant will occur due to the optimization of the thermal conditions of the sintering process by combining the burning layer of solid fuel with the heat transfer zone of the exhaust gases, aligning the gas-dynamic resistance of the sintered layer, providing an increase in the vertical sintering speed.

The improvement of the mechanical properties of the agglomerate will occur due to an increase in the gas permeability of the sinter layer and more efficient use of solid fuel.

With an increase in the fraction content of less than 0.5 mm in the solid fuel of the upper layer, this fraction will be rolled into granules of a pelletized agglomeration charge, which will lead to a decrease in the vertical sintering rate and, consequently, to a decrease in the specific productivity of the sinter plant. Diffusion of oxygen to the carbon of the fuel rolled up in the charge granule will be difficult, which will lead to a decrease in the temperature-thermal level of the sintering process, an increase in the amount of undercake and a deterioration in the mechanical strength of the sinter.

If the fraction content is less than 0.5 mm in the solid fuel of the upper layer, a corresponding redistribution of fineness will occur with an increase in the content of large fractions (more than 3 mm) in the solid fuel of the upper layer of the charge. The combustion of a larger fuel of the upper layer will be accompanied by a significant increase in the number of liquid phases, which lead to an increase in the gas-dynamic resistance of the combustion layer and a decrease in the vertical sintering rate, which determines a reduced specific productivity of the sinter plant.

The following is an embodiment of the invention, not excluding other embodiments, within the scope of the claims.

The sintering method of the sinter charge is as follows.

Example

The composition of the sinter mixture: iron ore concentrates wet magnetic separation, solid fuel, return and fluxing additives.

Before sintering the sinter charge on an sinter machine, the components of the sinter charge are metered in a predetermined ratio and mixed.

Half of the fuel is dosed in the housing of the charge silos. The rest of the fuel is screened with a screen with a mesh size of 4 × 50 mm; the resulting superlattice (fraction of more than 4 mm) and sublattice (fraction of less than 4 mm) are metered into the upper and lower layers of the sinter mixture, respectively. As a result of these operations, solid fuel of the upper layer contains 15-25% of the fraction of less than 0.5 mm, solid fuel of the lower layer contains 35-45% of the fraction of less than 0.5 mm.

The mixed charge is pelletized to a moisture content of 7.2-7.3%.

The pelletized charge is loaded onto the sintering machine using two loading devices of the lower and upper layer of the charge onto a previously laid “bed”.

Under the sinter plant create a vacuum within 700-900 mm of water.

When feeding the mixture to moving carts, it is ignited under an incendiary furnace. The thickness of the sintered layer is set within 360-420 mm, while the height of the upper layer is 1/3 of the height of the entire layer.

The table shows examples of the method of sintering the sinter mixture with different particle size distribution of the fuel based on laboratory experiments.

Method for sintering a sinter charge Indicator Names Series one 2 3 The content of fractions in the fuel of the upper layer,%: <0.5 mm 0 25 35 0.5-3 mm 80 60 52 > 3 mm twenty fifteen 13 The content of fractions in the fuel of the lower layer,%: <0.5 mm 45 38 35 0.5-3 mm fifty 52 52 > 3 mm 5 10 13 Specific productivity, t / (m ² · h) 0.895 0.961 0.942 Mechanical strength according to GOST 15137-77,%: indicator X (fr.> 5 mm) 67.23 68.40 64.10 exponent X ₁ (fr. <0.5 mm) 4.26 3,55 5.07 The yield of agglomerate,% 73.52 72.44 66.41 Vertical sintering speed, mm / min: 13.64 14.56 15.41

In the first series of experiments, due to a decrease in the fraction content of less than 0.5 mm to zero and a corresponding increase in the fraction content of more than 3 mm to 20% in the solid fuel of the upper layer, the required specific productivity of the sinter plant and the mechanical strength of the sinter are not provided.

In the third series of experiments, due to an increase in the fraction content of less than 0.5 mm to 35% in the solid fuel of the upper layer, the required specific productivity of the sinter plant and the mechanical strength of the sinter are not provided.

In the second series of experiments, due to the use of solid fuels of the recommended particle size distribution, an increase in the specific productivity of the sinter plant and an increase in the mechanical strength of the sinter occur.

Claims (1)

A method for sintering a sinter charge, including dosing the iron-containing part of the charge, solid fuel, fluxing additives, return, mixing the charge, pelletizing the charge, two-layer loading of the sinter charge on sintering trolleys, subsequent ignition of the charge, creating a vacuum under the sintering trolleys, characterized in that dosing solid fuel in the form of coke breeze is carried out by introducing it into the charge of the upper and lower layer with a fraction content of less than 0.5 mm in solid fuel 15-25% and 35-45%, respectively.