RU1770361C - Method of metallized sinter production - Google Patents

Abstract

Usage: the invention relates to ferrous metallurgy and is intended for sintering iron ores and concentrators, in particular for the production of metallized agglomerate. Essence: the method includes separate preparation, subsequent pelletizing of two batches: the first - in the form of large granules of finely dispersed wustite-containing materials, for example, scale or its mixture with concentrate and highly reactive fuels, the second - in the form of a mixture of fuel with iron-containing materials with the ratio Fe / + / Reobsh 0.33. Then the granules are simultaneously laid on sinter tape with a mass ratio of the mixture 1: 1 and sintered. The oxidation state of the first charge of oxidation Fe + / Ptot. 2: 0.5, and the amount of highly reactive fuel is 0.08 - 0.1 mass of the charge with a granule size of 8-9.5 mm. (L C

Description

The invention relates to ferrous metallurgy and is intended for sintering iron ores and concentrates, in particular for the production of metallized agglomerate.

Known methods for producing metallized agglomerate by increasing the amount of fuel in the sinter charge to 20% or more than 1J. An excess of fuel ensures the creation of a reduction potential in the combustion zone and an increased heat input. The finished agglomerate contains up to 20% metallic iron. The disadvantage of these methods is to increase the temperature level of the process, especially at lower sintering horizons and the formation of a large

amount of liquid phases. The re-melting of the charge sharply affects the gas permeability of the layer and leads to a decrease in sintering productivity

The closest in technical essence and the achieved result to the claimed is a method for producing metallized agglomerate, which consists in separately pelletizing finely dispersed concentrate and coarse-grained constituents of sinter charge (iron ore, fpus recovery) 2. Pellets of size 10- obtained from a mixture of concentrate and part of the fuel 20 mm, in which the Fez + / Fe06iM ratio was 0.33, was charged with the remaining ore-coal mixture.

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About GJ iCb

The best results were observed in experiments with an average fuel content in the sinter charge of 8.8 wt.%, Including in pellets - 12.7-, in the ore-coal mixture -3.5 wt.%, which ensured the degree of metallization of the sinter up to 27.1 - 27.8%. The production of metallic iron was made possible as a result of the local development of reduction processes in the internal volumes of the pellets while maintaining a high partial pressure of CO in them due to the difficult access of air oxygen to the central zones.

The disadvantage of this method is the increased carbon content in the pellets, due to the need to maintain a high reduction potential in the core of the pellets. At a low content (Fe2 + / Fe0bsc. 0.33), the total carbon consumption is determined by the amount of oxygen removed at both the FeO Fe and Fe204 - FeO stages. In addition, part of the carbon introduced in the peripheral zones is spent on a combustion reaction, accompanied by the formation of CO 3.

The need to create a high partial pressure of CO in the internal volumes of the pellets is also due to another drawback of the method - their increased size, since the predominant participation of carbon in the interaction with the oxide phases and the appearance of the metal phase is possible only at a sufficient distance from the outer oxidizing zone of the pellet.

When large pellets are used for sintering, the gas-dynamic characteristics of the charge, including its gas permeability, deteriorate, the speed of heating of the pellets, the vertical sintering speed, and the overall productivity of the process decrease.

The aim of the present invention is to increase the content of metallic iron in the agglomerate while reducing fuel consumption, improving the gas permeability of the bed and increasing the productivity of the sinter plant.

This goal is achieved by the fact that in the method comprising separate preparation, subsequent separate pelletizing of two charges, the first of which consists of finely dispersed iron-containing materials and fuel, and the second of coarse-grained materials and fuel with the ratio Fe + / Pe0bsc. 0.33, their simultaneous laying on sinter tape with a mass ratio of the charges 1: 1 and subsequent sintering, the first charge is prepared from finely divided

wustite-containing materials - scale or its mixture with a concentrate, in which the oxidation state indicator is Fe + / Ptot. 0.5, - and highly reactive

types of fuel in the amount of 0.08-0.10 mass of the charge and pelletize to a particle size of 8.0 to 9.5 mm

The presence of the above distinctive features from the prototype indicates that the claimed technical solution meets the criterion of novelty. Since the claimed combination of essential features allows us to achieve the goal - increasing the content of metallic iron while reducing fuel consumption, improving gas permeability of the bed and increasing the productivity of sinter plants - due to distinctive essential features, the invention meets the criterion of a positive effect by the presence of a difference in results when using the known and claimed decision.

In order to determine the conformity of the claimed technical solution to the criterion, significant differences were found for each distinguishing feature in the scientific and technical literature and patent documentation (main indices

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Since among the known technical solutions were not found that contain features similar to distinctive features and perform the claimed function, the proposed solution meets the criterion of significant differences.

The essence of the method lies in the fact that the use of highly reactive fuels in the granular components of the sinter charge ensures the creation of increased reduction potential in the granules with a relatively low carbon content in them. In this case, the temperature of the interaction of carbon with oxide phases is 100-200 ° C lower compared to the use of traditional fuels, i.e. reduction and metallization processes precede liquid phase sintering. The temperature level necessary for the development of solid-phase reduction is ensured by the combustion of the low-reaction fuel of the charge P. The metallization of the granules is also facilitated by reducing

with an increased FeO content of reduction work at the FesO / i - FeO stage, which is achieved by introducing mill scale into the charge 1. In connection with these features, the degree of metallization is increased.

sinter, fuel consumption is reduced, charge overheating is reduced, and sinter plant productivity is increased.

The greatest effect is achieved with a granule size of at least 8 mm. Otherwise, the development of the metallization step is hindered due to the predominant consumption of fuel for its combustion reaction and the creation of an oxidizing potential in the chain by volume of granules with respect to the FeO - Fe step. An increase in their size over 9.5 mm is accompanied by a deterioration in the gas permeability of the layer. In addition, the use of large granules makes it difficult to heat the inner zones, worsens the thermal regime, reduces the vertical sintering speed and sintering productivity

In order to maintain the reduction potential in the granules, the content of highly reactive fuel in them should be at least 0.08 of the charge mass. An increase in fuel consumption in excess of 0.1 mass of the charge, having practically no effect on the degree of metallization, is impractical due to an increase in temperature in the layer, deterioration of gas permeability and a decrease in plant productivity.

A positive effect is observed when there is an increased content of ferrous iron in the granules, the presence of which can be interpreted as pre-recovery carried out outside the agglomeration belt. The degree of oxidation of the granular charge, expressed by the criterion Fe2 + / Pe0bsc., Must be at least 0.5. Such an indicator is ensured by introducing into the granular charge 1, in addition to the concentrate, up to 25% of scale. An increase in the content of scale from 25% to 100%, g. up to its complete replacement of the concentrate, it creates favorable conditions for the development of metallization without impairing the basic parameters of the process.

PRI me R. Under identical conditions, comparative experimental sintering of metallized agglomerate was carried out in a laboratory setup with a stationary bowl. The mass of the sintering sinter charge was 20 kg, the layer thickness was 350 mm and the dilution was 10 kPa.

Blends I and il were prepared and ovate separately. Batch 1 consisted of large granules obtained on a plate granulator from a mixture of finely dispersed materials - iron ore concentrate and mill scale with the addition of highly reactive fuel. Charcoal was used as the latter in connection with its relative cheapness and affordability. However, other highly reactive carbonaceous materials can be used, for example, brown coal semicoke, molded coke, etc.

Fine-grained charge II, consisting of

oxidized iron ore, return, flux and 3.5% (by weight) of low-reactivity coke breeze, mixed and pelletized in a drum. Then both charges in the ratio 1: 1 were simultaneously laid on the grate.

12 experiments were conducted in each of which the size of the granules and the content of the components of the charge in them were varied as

within and outside the scope of the claims. To compare the experiments with granules obtained from a mixture of concentrate and fuel in the form of a low-reactivity coke breeze (the reactivity of coke breeze in the reaction C + CO2 2CO was 0.29-0.33). During the tests, the specific productivity of the installation and the content of metallic iron in the charge were determined.

The results of the experiments are presented in the table

The data in the table show that an increase in the metallization degree, a decrease in fuel consumption and an increase in sintering machine performance are achieved by using highly reactive fuel in an amount of 0.09 from the mass of granules with a size of 9 mm. process indicators.

The proposed method for producing metallized agglomerate in comparison with the known (experiment 12) provides an increase

metallization degree by 8.7 - 12.4%, reduction of fuel consumption in granules by 3-4% and, on average, by a layer of NS 2.5% increase in sinter machine productivity by 0.1 - About 25%

Thus, the studies carried out confirmed the possibility of obtaining a metallized agglomerate with a high content of metallic iron, a reduced fuel consumption and improved sintering performance.

Claims (1)

The claims A method for the production of metallized agglomerate comprising separate preparation, subsequent separate pelletizing of two charges, the first of which consists of finely dispersed iron-containing materials and fuel, and the second of coarse-grained materials and fuel not, about, wearing He / Real S0.33, simultaneous-Jhyro laying them on an agglomerate with mass coot of carrying charges 1 1 and subsequent sintering, characterized in that, in order to increase the content of metallic iron in the agglomerate and at the same time reduce fuel consumption , improving the gas permeability of the layer and increasing the productivity of the installation, the first charge is prepared from finely dispersed viscous-containing materials-scale or its mixture with a concentrate in which the oxidation state of Fe / Real 0.5 and highly reactive fuels in the amount of 0.0 8-0.10 mass of the mixture is pelletized to a particle size of 8.0-9.5 mm 4 5 6 7 8 b  About 11 1