RU2304626C1 - Charge for production of the agglomerate - Google Patents

Abstract

FIELD: metallurgy; charges for production of the sinter in ferrous metallurgy and non-ferrous metallurgy.

SUBSTANCE: the invention is pertaining to metallurgy, and may be used in production of agglomerates in ferrous metallurgy and nonferrous metallurgy, in particular, in the blast-furnace production. The charge consists of the mixture of the components of the iron-ore substance, the fuel, the fluxing agent and the binding agent, in the capacity of which they use the disperse iron-plated dolomite at the following ratio of the components (in mass%): the fluxing agent - 5÷20; the fuel - 3÷10; the disperse iron-plated dolomite - 0.5÷5; the iron-ore substance - the rest. The dispersed iron-plated dolomite of the agglocharge contains 5-80 % of the colloid particles with dimensions from 400 up to 1 nanometer. The great specific surface area of the disperse phase, its active physicochemical interaction with the disperse medium magnifies the adhesive forces of the particles of the charge, improves the lump-forming capacity of the agglocharge, improves the quality of the agglomerate concerning its abradability, strength, restorability, to the contents of brimstone and fines of 5-0 mm, increases the specific efficiency of the agglomeration plant.

EFFECT: the invention ensures the magnified adhesive forces of the particles of the charge, the improved lump-forming capacity of the agglocharge, the improved quality of the agglomerate concerning its abradability, strength, restorability, the increased specific efficiency of the agglomeration plant.

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Description

The invention relates to metallurgy and can be used in the production of agglomerate in ferrous and non-ferrous metallurgy, used, in particular, in blast furnace production.

A known mixture for the production of sinter, consisting of a mixture of components of iron ore material, fuel, flux, including, as a thermite additive, high-carbon partially reduced iron ore raw materials with a metallization degree of 25-80%, in the following ratio of components, wt.%: Flux 15 ÷ 25; solid fuel 4 ÷ 6; high-carbon partially reduced iron ore raw materials with a metallization degree of 25-80% - 3 ÷ 7, iron ore material - the rest (USSR AS No. 1664857, class C22B 1/16).

Due to the relatively high particle size of the component particles, the known sinter charge includes unfilled free cavities, as a result of which when dispersing, weak dispersion adhesion forces between the component particles do not provide the known charge with high clumping properties. For these reasons, the agglomerate quality is relatively low in terms of abrasion, reducibility and fines content of 5-0 mm and the specific productivity of the sinter plant. Reduced iron as a component of the known sinter charge absorbs sulfur during the sintering process, as a result of which the product is obtained with a high content of this harmful impurity. The removal of sulfur is also complicated by the up to 25% consumption of the flux component in the known sinter charge.

The closest analogue to the claimed object is a mixture for the production of agglomerate, consisting of a mixture of components of iron ore material, fuel, flux, including catamine as a binder, in the following ratio, wt.%: Flux 5 ÷ 10; fuel 5 ÷ 10; catamine 0.01 ÷ 0.03, iron ore material - the rest (Russian Patent No. 225125, class С22В 1/244, publ. 06/27/05).

A disadvantage of the known sinter charge is also the relatively high particle size of the particles of its components, as a result of which, when pelletizing, unfilled free cavities between the particles reduce the effect of molecular adhesion forces in the wet sinter charge. For these reasons, it is not possible to achieve a high level of specific productivity of the sinter plant, the quality of the sinter by abrasion, reducibility, sulfur and fines content of 5-0 mm.

An object of the invention is to increase the adhesion forces of dispersed particles of sinter charge components, improve clumping properties of sinter charge, improve sinter quality in terms of abrasion, strength, reducibility and sulfur content, fines content of 5-0 mm, increase specific productivity of the sinter plant.

The problem is solved in that the known mixture for the production of sinter, consisting of a mixture of components of iron ore material, fuel, flux and a binder, according to the invention includes as a binder dispersed iron dolomite in the following ratio of components, wt.%: Flux - 5 ÷ 20; fuel - 3 ÷ 10; dispersed ferruginous dolomite - 0.5 ÷ 5; iron ore material - the rest.

In the claimed sinter charge, the binder component from dispersed ferruginous dolomite contains 5-80% of colloidal particles ranging in size from 400 to 1 nm. Its chemical composition is as follows:

Fe ₂ About ₃ SiO ₂ Al ₂ O ₃ Cao MgO PMPP 1-2 1.5-2.5 0.3-0.4 38-45 20-25 24-30

Dispersed systems are characterized by a large specific surface of the dispersed phase and the active physicochemical interaction of the dispersed phase and the dispersion medium at the phase boundary. The specific surface of spherical particles is 6 / d, cubic - 6 / l, where d is the diameter and l is the length of the rib. The total surface of 10 nm particles obtained from 1 cm ^{3 of} substance is about 600 m ² . With increasing dispersion of a substance, its properties, determined by surface phenomena, are becoming increasingly important. In the boundary layer, molecules of particles of dispersed ferruginous dolomite interact with molecules of different chemical nature. At the interface, processes spontaneously occur in the direction of decreasing free surface energy equal to the product of its specific value (σ) by surface area (S). The product σS tends to the minimum value possible for a given system. A decrease in σ at the phase boundary is the cause of adsorption processes. A decrease in the total surface (S) leads to a decrease in dispersion, i.e. to particle aggregation. Particles of the dispersed phase turn into a gel. Dispersion forces of attraction act between the particles, ensuring the creation of a dense structure.

Moisture adsorption on the surface of the components of the sinter mixture leads to the appearance of molecular adhesion forces (F) between the particles. The value of F is described by the equation of V.I. Korotich:

F = K · S · p · (1-ε) / ε,

where K is a coefficient taking into account the shape of the particles, the nature of their packing, the hydrophilicity of the material, the chemical interaction of moisture with particles;

S is the specific surface of the dispersed material;

p is the density of the material;

ε is the porosity of particles bound into aggregates.

In the claimed ratio of sinter charge components, the use of dispersed ferruginous dolomite increases the adhesion forces (F) between the particles of the sinter charge due to an increase in the specific surface of the dispersed material (S), a decrease in the porosity of particles bound into aggregates (ε), and chemical interaction of moisture with CaO and MgO dolomite (increase TO). The decrease in ε occurs due to the filling of voids between the relatively large other components of the sinter charge by dispersed particles.

When the flux content in the sinter mixture is less than 5%, a decrease in its porosity and binding of FeO to fayalite (2FeOSiO ₂ ) impairs the quality of the agglomerate in terms of reducibility.

When the flux content in the sinter mixture is more than 20%, the quality of the sinter in terms of sulfur content deteriorates due to its absorption by calcium oxide with the formation of CaS sulfide.

When the fuel content in the sinter mixture is less than 3%, the agglomerate is not baked and therefore has increased abrasion, sulfur and fines 5-0 mm. Specific productivity becomes lower due to reduced yield of agglomerate.

When the fuel content in the sinter mixture is more than 10%, the sinter has a low reducibility due to a decrease in the porosity of the sinter and the formation of refractory minerals. Elevated temperatures worsen the removal of sulfur from the agglomerate due to the exothermicity of the desulfurization reactions. Agglomerate is obtained with a high sulfur content. Specific productivity decreases due to a decrease in the vertical sintering rate due to excessive formation of a liquid phase.

The claimed content of the dispersed ferruginous dolomite in the sinter mixture is set in the range of 0.5-5% by weight. Within these limits, the increase in adhesion between the particles with the pelletizing of the charge is most fully manifested. When the content of the dispersed ferruginous dolomite is less than 0.5%, it is not enough to achieve optimal lumpiness of the charge. The use of insufficiently pelletized mixture reduces the specific productivity and quality of the sinter in strength, abrasion, sulfur and fines 5-0 mm due to a decrease in the gas permeability of the sinter mixture, which complicates the flow of air to the fuel.

When the content of dispersed ferruginous dolomite in the mixture is more than 5%, it overflows voids between relatively large other components of the sinter mixture. From this, the values of K and ε decrease in the formula of V.I. Korotich. Molecular adhesion forces (F) between the particles are reduced, which again leads to a deterioration of the agglomeration charge pelletization with a decrease in specific productivity, agglomerate quality in terms of abrasion, reducibility, sulfur and fines content of 5-0 mm.

To substantiate the advantages of the inventive charge for the production of sinter, pilot tests were conducted on the sinter bowl of OJSC "Magnitogorsk Iron and Steel Works" with a diameter of 430 mm, equipped with an exhauster with the following characteristics:

rotor speed, rpm .............. 2900

suction pressure, kPa ...................... 16

productivity, m ^{3 /} min....................100

In the conditions of the prototype used catamine according to TU 6-01-816-75 in an amount of 0.02 wt.% In the following ratio with components, wt%: flux - 7.5; fuel - 5.5; iron ore material - the rest.

In the conditions of the claimed invention, the composition of the sinter charge was as follows, wt.%: Flux - 7.5; fuel - 5.5; dispersed iron dolomite - 2.75; iron ore material - the rest. Dust from electrostatic precipitators used in the production of ferruginous dolomite for steelmaking in the cement-refractory production of Magnitogorsk Iron and Steel Works OJSC was used as dispersed iron dolomite. Its chemical composition is presented in table 1.

Table 1
Chemical composition of dust from electrostatic precipitators Mass fraction,% Fe ₂ O ₃ SiO ₂ Al ₃ O ₂ Cao MgO PMPP 1,5 2.1 0.35 41.35 23.32 28.90

The claimed dispersed ferruginous dolomite contained 37% colloidal particles ranging in size from 400 to 1 nm.

The results of sintering of the agglomerate, obtained with different quantitative contents of the dispersed iron dolomite in the composition of the inventive sinter mixture, are presented in table 2.

Tests have shown that the claimed content (compositions 3-5 of Table 2) of the content of dispersed ferruginous dolomite in the composition of the sinter charge ensures the production of high quality agglomerate in terms of abrasion, strength, recoverability and sulfur content, fines content of 5-0 mm: agglomerate abrasion in 1.03- 1.13 times, the yield of fines of class 5-0 mm from the cake is 1.03-1.12 times, the sulfur content in the sinter is 1.08-1.12 times lower; recoverability is 1.01-1.04 times higher. The claimed (compositions 3-5 of Table 2) the content of dispersed ferruginous dolomite in the composition of sinter charge increases the specific productivity of the sinter plant by 1.07-1.11 times. Going beyond the declared limits (compositions 1, 2, 6 of Table 2) of the content of dispersed ironed dolomite in the composition of sinter charge leads to a decrease in the quality of the sinter in terms of abrasion, strength, recoverability and sulfur content, fines content of 5-0 mm and specific productivity of the sinter plant.

table 2
The results of sintering of agglomerate with different content of dispersed ferruginous dolomite in the inventive sinter The ratio of components in the inventive sinter charge, wt.% Sinter production quality indicators,% dispersed ferruginous dolomite (composition number) fuel flux iron ore material specific productivity, t / (m ² h) agglomerate abrasion according to GOST 15037-77 (-0.5 mm),% recoverability,% yield of fines of class 5-0 mm from spec,% sulfur content in sinter,% 0 (1) 5.5 7.5 87.0 1.68 5.9 46,4 12,2 0,041 0.4 (2) 5.5 7.5 86.6 1.76 5,6 46.5 11.8 0,040 0.5 (3) 5.5 7.5 86.5 1.82 5.3 46.6 11,4 0,038 2.75 (4) 5.5 7.5 84.25 1.86 5.3 48,2 10.9 0,038 5 (5) 5.5 7.5 82.0 1.86 5.8 48,2 11.8 0,037 5.1 (6) 5.5 7.5 81.9 1.74 5.95 47.9 12.0 0,040

The results of the production of sinter from a known charge and claimed using dispersed ironed dolomite from electrostatic precipitators are presented in table 3.

Table 3
The sintering results of the known and claimed charge No. p / p The name of indicators Experiences famous charge claimed charge one The height of the layer of the charge, mm 260 260 2 Vertical sintering speed, mm / min 22.6 23.1 3 Specific productivity, t / (m ² h) 1.68 1.86 5 The strength of the sinter according to GOST 15037-77 (+5 mm),% 55.8 65.3 6 Abrasion of agglomerate according to GOST 15037-77 (-0.5 mm),% 5.9 5.3 7 The output of small things of class 5-0 mm from the spec,% 12,2 10.9 8 Recoverability,% 46,4 48,2 9 The sulfur content in the agglomerate,% 0,041 0,038

The test results showed that the inventive charge provides high quality agglomerate in comparison with the known prototype for abrasion, strength, reducibility and sulfur content, fines content of 5-0 mm: vertical sintering speed of 1.02 times, the strength of the sinter 1.17 times The recoverability is 1.04 times higher; the agglomerate abrasion and the yield of fines of the class 5-0 mm from the cake is 1.11 times, the sulfur content in the agglomerate is 1.08 times lower. The inventive mixture for the production of sinter compared with the known prototype increases the specific productivity of the sinter plant by 1.11 times.

Claims (1)

The mixture for the production of sinter, consisting of a mixture of components of iron ore material, fuel, flux and a binder, characterized in that it includes as a binder dispersed iron dolomite in the following ratio, wt.%: flux 5 ÷ 20 fuel 3 ÷ 10 dispersed ferruginous dolomite 0.5 ÷ 5 iron ore material rest