RU2313588C2 - Method for preparing of sinter burden for sintering treatment - Google Patents

Abstract

FIELD: ferrous metallurgy, in particular, preparing of sinter feed, may be used in preparing of iron-ore raw materials for metallurgical treatment.

SUBSTANCE: method involves introducing iron-ore products, metallurgical production recycled materials, flux and fuel into sinter burden; mixing and balling resultant mixture; introducing part of iron-ore products in the form of concentrate of roasting magnetic concentration of sideroplesite produced after roasting of sideroplesite ore at temperature of 850-1,050 C and dry magnetic separation of roasted product in fields having intensity of 1,000-1,200 oersted, mixed with metallurgical production recycled products and iron-ore concentrates in the ratio of (0.08-0.20):(0.05-0.15):1.00. Sideroplesite roasting-magnetic concentration product contains the following components, wt%: iron total 47-52; magnesium oxide 10-14; calcium oxide 2-5; silicon oxide 2-5; manganese oxide 1.0-2.0; aluminum oxide 1.5-1.8, and contains mass parts having sizes exceeding 10 mm and less than 0.1 mm in an amount of 0-10% and 35-50%, respectively.

EFFECT: increased capacity of sintering machine and increased strength of sinter on producing of its optimal composition for forming of liquid flowing blast-furnace slag.

3 cl, 2 tbl, 1 ex

Description

The invention relates to the field of ferrous metallurgy, in particular to the production of sinter, and can be used in the preparation of iron ore for metallurgical processing.

A known mixture for the production of sinter, including chemical waste, scale, blast furnace dust, blast furnace sludge, limestone, coke breeze, characterized in that in order to increase the strength of the sinter it additionally contains vanadium-containing sludge from thermal power plants (TPP) with the content of ingredients, wt.% [ one]:

 chemical waste  8-15  scale  35-55  blast furnace dust  10-15  blast furnace slurries  8-15  limestone  3,5-9,0  TPP vanadium sludge  2-25

In addition, 40-60% of the vanadium-containing sludge of TPPs has a particle size of less than 0.1 mm.

A disadvantage of the known mixture is that the agglomerate obtained from it has low metallurgical properties. The absence of rich concentrates leads to the fact that the content of Fe does not exceed 50-52%, and reinforcing additives to low strength, especially during recovery.

A known method for the production of fluxed iron ore sinter, in which, after pelletizing a multicomponent mixture, a fraction (-3 mm) is isolated and its basicity and alumina module (Al ₂ O ₃ / SO ₂ ) are determined.

Given these indicators, which must be maintained in the range of 1.6-2.2 units. and 0.2-0.5 units. accordingly, the sintering mode parameters are set at which the oxygen content in the exhaust gases is 10-17% [2].

This method allows to obtain a strong agglomerate due to the formation of aluminosilicoferrite slag binder, absorbing silica and preventing the formation of dicalcium silicate. However, the use of this technology is limited by the need to make sinter charge only from alumina-containing iron ores and concentrates of a certain composition. At the same time, aluminate blast furnace slags formed during the sinter melt are usually refractory and poorly filtered through a coke nozzle. This reduces the gas permeability of the charge column in blast furnaces and, accordingly, their productivity.

The closest in technical essence and the achieved result is a method of preparing for sintering the sinter mixture [3], which includes dosing and introducing into the mixture of iron-containing materials, metallurgical products, fluxes and fuels, mixing and pelletizing. A part of the circulating products of metallurgical production is introduced in the form of a metal concentrate obtained by processing and enrichment of waste waste from metallurgical production, and it is mixed with iron-containing materials in the ratio, respectively (0.02-0.10): 1.0.

The metal concentrate is used with a fraction of 0-10 mm, having the following chemical. composition, wt.%: iron 56.9-86.0; carbon 2.0-4.7; manganese 0.1-1.2; silicon 0.3-3.6; calcium oxide 4.2-16.8; magnesium oxide 0.6-2.4; iron oxide 0.5-7.0; manganese oxide 0.01-0.4; silica 3.8-15.2; alumina 0.7-3.6; phosphorus 0.09-0.3; sulfur 0.04-0.6; graphite 1.3-7.2; phosphorus pentoxide 0.3-0.6.

The presence of metallic iron and graphite in a metal concentrate saves solid fuel during sintering.

The disadvantages of the prototype are:

- insufficiently high productivity of sintering machines and strength of cake due to the presence of metal concentrate, initiating local overheating of the layer during oxidation of Fe and C;

- the absence in the sinter charge of components that can maintain the desired ratio of Al ₂ O ₃ / MgO in the sinter, ensuring the formation of low-melting homogeneous slags in blast furnaces.

The technical result of the invention is to increase the productivity of sinter machines and the strength of the sinter while ensuring its optimal composition for the formation of fluid blast furnace slag.

The technical result is achieved by the fact that the known mixture containing iron ore concentrates, recycled products of metallurgical industries and their metal concentrates, fluxes and fuel according to the invention additionally contains iron ore concentrate siderolesite, calcined at 850-1050 ° C and subjected to dry magnetic separation in fields of 1000- 1200 erst., Mixed with circulating products of metallurgical industries and iron ore concentrates in the ratio (0.08-0.20) :( 0.05-0.15): 1.

Sideroplezite firing enrichment concentrate contains total iron 47-52%, Mg-oxide 10-14%, Ca-oxide 2-5%, Si-oxide 4-8%, nitrous oxide Mn 1.0-2.0%, Al trioxide 1.5- 2.5%.

The concentrate of firing enrichment of sideroplezite is crushed in such a way that the mass fraction of a fraction of more than 10 mm and less than 0.1 mm is 0-10% and 35-40%, respectively.

The essence of the method is as follows. The use of recycled products in the sinter charge in the form of waste from metallurgical industries with a high content of aluminum oxide in ores and concentrates leads to the formation of refractory viscous aluminate slags during the melting of agglomerates having an aluminate module Al ₂ O ₃ / MgO greater than 1.0 in blast furnaces. To reduce the viscosity of blast furnace slag, it is necessary to maintain the ratio of Al ₂ O ₃ / MgO in the agglomerate and blast furnace slag in the range of 0.7-1.0. To this end, it is proposed to introduce a magnesia concentrate obtained by firing magnetic enrichment of raw sideroplezite ore containing 30-32% Fe, 8-10% MgO, 1.8-2.3% Al ₂ O ₃ , 6-8 SiO ₂ , 35-37% CO ₂ . To remove harmful impurities SiO ₂ , Al ₂ About ₃ and CO ₂ sideroplezite ore is fired at 850-1050 ° C and subsequent magnetic separation. During firing, carbon dioxide is removed and iron oxide is oxidized by the reactions:

Due to the removal of CO _{2, the} mass fraction of Fe in the calcined ore rises from 30-32% to 44-46%, and MgO from 8-10% to 10-11%. During firing, an isomorphic solution of Fe and Mg carbonates forms magnetic magnesioferrites; therefore, magnetic separation of calcined ore in fields with a strength of 1000-1200 erst. allows you to separate iron-magnesian minerals from aluminosilicate waste rock. The resulting concentrate contains 47-52% Fe, 10-14% MgO, 1.5-1.8 Al ₂ O ₃ , 4-5% SiO ₂ and has a very low aluminate module Al ₂ O ₃ / MgO = 0.1- 0.2 units The addition of sideroplezite concentrate to sinter charge containing waste from metallurgical production and aluminate iron ore materials will optimize the composition of the sinter and ensure the formation of fluid blast furnace slag during sinter smelting.

The introduction of an iron-magnesian concentrate of roasting magnetic enrichment of sideroplezite allows not only to optimize the composition of blast furnace slag during the sintering process, but also to increase its strength, especially after recovery in the upper horizons of blast furnaces. Mg ^{2+ ions} , having high diffusion mobility, are actively introduced into the magnetite lattice of iron ore components, linking part of the hematite formed during its oxidation to magnesium ferrites by the reactions:

Mg ferrites swell much less and break down during reduction in the upper horizons of blast furnaces than hematite, while maintaining the strength of the agglomerate.

Side roesite, when fired in the temperature range of 850-1050 ° C, acquires porosity due to the low-temperature phase transition of carbonates to oxides under conditions of low diffusion mobility of atoms. As a result, when grinding it, it is possible to select such a mode of operation of the mills that both large pieces of a fraction of 3-10 mm and very small fractions of less than 0.1 mm are formed. Large pieces of 3-10 mm when laying the sinter charge on the machine due to centrifugal forces fall on the grate, forming a kind of bed that protects the space between the grate from sticking. The fines of sideroplezitic concentrate of 0.0-0.1 mm, having inclusions of burnt magnesia, contribute to the pelletization of fine fractions of iron ore components, improving the gas permeability of the sinter charge and increasing the performance of the sinter tape and the strength of the cake.

The firing temperature limits for sideroplezitic ore are due to the need to obtain the required particle size and chemical composition of the concentrate. At t <850 ° С, Fe and Mg carbonates do not completely decompose according to reactions (1) and (2), reducing the level of magnetic properties of the calcined product and the efficiency of magnetic separation. Therefore, the concentration of harmful impurities CO ₂ , Al ₂ O ₃ and SiO ₂ in the concentrate does not ensure the achievement of the technical objectives of the invention, in particular, the optimal composition of blast furnace slag during sinter melting.

At t> 1050 ° С, sideroplezitic ore begins to melt. This complicates the operation of firing units and does not provide the required ratio of small and large classes in the crushed concentrate of firing-magnetic enrichment of sideroplezite.

The limits of magnetic field strength during the separation of calcined sideroplezite are due to the need to obtain an optimal composition concentrate with minimal iron loss. With a tension of less than 1000 erst. only components very rich in the content of Fe and Mg are extracted into the magnetic fraction and iron losses exceed 15-20%. With a tension of more than 1200 erst. the concentrate is contaminated with harmful impurities of weakly magnetic aluminosilicate iron-containing inclusions.

The limits on the ratio of the concentrate of calcinous enrichment of sideroplezite and iron ore concentrate are due to the production of a durable agglomerate with an optimal composition for the formation of fluid-moving blast-furnace slag. With a share of sideroplezitic concentrate less than 0.08 units. the strength of the sinter after recovery is insufficient and the ratio Al ₂ O ₃ / MgO = 0.7 units required by blast furnace conditions is not achieved. With a share of sideroplezitic concentrate of more than 0.2 units, refractory magnesian slags are formed.

The limits on the ratio of working products of metallurgical processing and iron ore concentrates are due to the production of strong cakes and the need to produce agglomerates with a low content of harmful impurities, Zn and alkali metals that accumulate in blast furnace dust, slag and sludge. When the ratio of negotiable products is less than 0.05 units. the consumption of almost free iron in blast furnace dust, sludge and slag concentrates has been unreasonably reduced. With a ratio of more than 0.15, the strength of the agglomerate decreases due to the deterioration of the lumpiness of the agglomeration mixture containing a large number of hydrophobic dusts and slag concentrates. In addition, when the ratio of circulating products is more than 0.15, Zn, Na and K accumulate in the agglomerates and their content exceeds 0.1%. The smelting of such agglomerates leads to premature wear of the lining of blast furnaces and a decrease in their productivity.

The limits on the ratio of fractions of more than 10 mm and less than 0.1 mm in sideroplezite concentrate are due to the achievement of maximum productivity of the sinter machine with high sinter strength. The presence of pieces larger than 10 mm more than 10% leads to the fact that they are not absorbed by the melt and soften the cake. The content of the classes of 0.0-0.1 mm less than 35% does not provide the required astringent properties of the iron-magnesian siderolesite for pelletizing rich concentrates, and more than 50% unnecessarily grinds the sinter mixture and reduces the gas permeability of its layer and, accordingly, the productivity of sinter machines.

A comparative analysis of the proposed technical solution with the prototype showed that the preparation method for sintering the sinter mixture differs from the known one in that iron-magnesia concentrate for calcining sideroplezite enrichment obtained after roasting sideroplezite ore at 850-1050 ° C, magnetic separation in fields of 1000 -1200 erst. and grinding to a particle size of 35-50% cells. less than 0.1 mm. These signs are not in the prototype. Thus, the claimed method meets the criterion of "novelty."

An analysis of the methods for preparing for sintering agglomeration blends known in the technical and patent literature did not reveal their use for the purpose of producing a solid in the initial state and for reducing an agglomerate having an optimal composition with respect to Al ₂ O ₃ / MgO and obtained on an agglomerate operating with increased productivity. This indicates the compliance of the invention with the criterion of "inventive step".

The method was carried out as follows.

Sideroplezitic ore with a particle size of 10-80 mm was calcined in shaft furnaces of the Bakalsky RU at temperatures of 850-1050 ° C for a time sufficient for its decarbonization by 90-95%. After cooling to 100 ° C, the calcined ore was rumbled with the separation of grades 10-60 mm and 0-10 mm. Each fraction was separately subjected to dry magnetic separation on drum-type apparatuses with a field strength of 1000-1200 erst. A lumpy fraction of the calcined sideroplezite concentrate was crushed in cone crushers, mixed with a fraction of 10-0 mm, moistened to 5% to exclude dusting, and sent to Vysokogorsk GOK to prepare sinter charge.

Iron-containing waste from metallurgical industries (blast furnace dust, blast furnace steel and sintering sludge, as well as slag processing concentrates, etc.) were evenly stacked.

Rich concentrates obtained by enrichment of magnetite ores of wet magnetic separation, and crushed ores were laid in separate stacks.

After the formation of stacks, the materials from them were pumped into dedicated bins.

The calcined sideroplezite concentrate, like limestone and solid fuel, was pumped into separate hoppers for accurate dosing.

Components from hoppers of concentrates, ores, waste, calcined sideroplezite concentrate, limestone, and fuel were fed by tape dispensers to a collection conveyor and averaged in a drum mixer. Mixed and moistened to 5-7%, the mixture was pelletized in a drum pelletizer and placed on sintering machine pallets for sintering. Sinter after crushing and separation of hot return with a particle size of 5-0 mm was sent to the NTMK blast furnace shop for the production of pig iron. Return served in the mixing drum to heat the mixture.

Examples of the method

The chemical composition of stacks, concentrate, ores and waste from metallurgical industries, as well as calcined sideroplezite, limestone and fuel concentrate, is presented in Table 1.

The strength of the sinter in the cold state was determined in a standard drum according to GOST 15137-87.

The strength of the agglomerate after reduction and the degree of reduction at 800 ° C were determined in a Linder-type apparatus according to GOST 19576-86.

The viscosity of blast furnace slag during sinter melting was calculated using a special PC program compiled on the basis of experimental viscosity diagrams in the CaO-SiO ₂ -Al ₂ O ₃ -MgO system.

Table 1
The chemical composition of the main components of sinter charge when checking the proposed method Items Mass fraction of elements in sinter charge components,% MMS concentrate mixture CMC Concentrate Mix Slag slurry mixture Calcined sideroplezite concentrate, Bakalsky RU Limestone Coke Ash Fe _commonly 62.6 52,4 50,0 48.5 - - FeO 24.0 15.0 11.5 5,0 - - Fe ₂ O ₃ 62.8 58.2 58.6 63.7 - - CaO 1.9 5,6 6.0 3,7 53.3 5.2 SiO ₂ 5,4 10.0 6.2 5,0 1,1 43.8 MgO 1,5 1,2 6.6 13.0 0.5 2,4 MnO 0.5 0.7 1,0 2.0 - - S _total 0.3 2.9 0.3 0.1 0.04 0.2 RFP 1,2 2.0 8.8 5,0 42.0 - Σ oxides 97.9 95.6 99.0 97.5 96.9 -

The performance of the sintering process of agglomerates with a basicity of CaO / SiO ₂ = 1.1-1.2 units. and containing 55.0-55.2% Fe, the viscosity of primary blast furnace slag and coke consumption during melting are presented in table 2.

It follows from this that the addition of the Bakalsky RU natural-alloyed KOS instead of the ore mixture, while maintaining the iron content in the sinter at a level of 55.1%, allows to increase the sinter plant productivity from 1.25 t / m ² hour to 1.30-1.38 t / m ² hours (7%) due to an increase in the vertical sintering speed. At the same time, in the claimed temperature range of firing WWTP, magnetic field intensity during its separation and size, while maintaining the ratio of “WWF: f / r concentrates” in the range (0.08-0.20): 1, and “waste: f / concentrates "In the range of (0.05-0.15): 1, we obtain the following advantages compared to the known method (see examples 2, 3):

- the strength of the sinter in the cold state according to GOST 15137-87 increased from 60% to 62-65%;

- the strength of the sinter after recovery according to GOST 19576-86 increased from 12% to 20-28%;

- coke consumption in blast furnace sinter due to its hardening and optimization of chemical. composition decreased from 470 to 452-460 kg / t of pig iron.

table 2
The results of industrial tests of the proposed method of preparation for sintering the sinter mixture №№p / p Indicators Sample Numbers one 2 3 four 5 6 7 8 9 one 2 3 four 5 6 7 8 9 10 eleven one The consumption of ore and flux charge materials, wt.% - CBS 0 5 10 fifteen 10 10 10 10 10 - a mixture of MMS concentrates 46.6 46.5 46.3 46.0 46.0 46.7 46.2 46.8 46.3 - a mixture of CMC concentrates 33.7 30.8 28.0 23,2 22.0 27.3 27.8 27.7 28.0 - slag slurry mixture 10,4 8.7 7.8 8.3 15.0 8.0 8.0 8.0 7.8 - limestone 9.3 9.0 7.9 7.5 7.0 8.0 8.0 7.5 7.9 2 Ratios, units: - "CBS: oil concentrates" - 0.06 0.13 0.22 0.15 0.13 0.13 0.13 0.13 - "slag slurry mixture: railway concentrates 0.12 0.11 0.10 0.12 0.22 0.11 0.11 0.11 0.10 3 KOS firing temperature, ° С - 950 950 950 950 800 1100 1000 950 four Magnetic field during separation of calcined sideroplezite, oersted 1100 1100 1100 1100 1100 1100 1350 1100 5 Coarseness + 10 mm - 10.0 8.0 8.0 8.0 10.0 15.0 10.0 5,0 CBS, wt.% -0.1 mm - 35.0 45.0 45.0 45.0 36.0 28.0 42.0 65.0

Continuation of table 2 №№p / p Indicators Sample Numbers one 2 3 four 5 6 7 8 9 one 2 3 four 5 6 7 8 9 10 eleven 6 Productivity of sinter machines, t / m ² hours 1.25 1.30 1.35 1.38 1.23 1.28 1.25 1.25 1.15 7 Fuel consumption in the agglomeration, kg / t. 40 40 40 40 42 45 42 47 fifty 8 The strength of the sinter in the initial state according to GOST 15137-87 (class +5 mm) 60.0 62.0 65.0 63.0 59.0 60.0 60.0 58.0 58.5 9 The strength of the sinter after recovery according to GOST 19576-86 (class + 10 mm) 12.0 20,0 28.0 28.5 25.5 25.0 18.0 22.5 15.0 10 The viscosity of blast furnace slag at 1400 ° C and the basicity of CaO / SiO ₂ = 1.0 units 6.5 5.5 5,0 6.8 5.7 5,6 5.5 6.0 5.8 eleven Coke consumption in blast furnace sintering, kg / t.chug 470 460 452 468 470 458 470 465 468

A higher than the claimed limit on the consumption of WWTP (example 4), leads to an increase in the viscosity of blast furnace slag during sintering and overuse of coke, which practically does not differ from the known method.

A higher than the claimed limit on the consumption of slag slurry mixture (example 5), significantly worsens the strength of the sinter and also leads to overuse of coke.

The decrease in the temperature of roasting siderolesite ore below the claimed limits to 800 ° C (example 6) leads to an excessive consumption of fuel in the sinter process for decomposition of residual carbonates and a decrease in the productivity of sinter machines almost to the level of the known method. An increase in the firing temperature above the claimed limits reduces the strength of the sinter due to poor lumpiness of the charge and leads to excessive consumption of coke in blast furnaces (example 7).

The excess of the magnetic field in relation to the claimed limits (example 8) causes the unburnt sideroplezite to enter the WWTP with a decrease in sinter productivity and an increase in fuel consumption both in sintering and in the blast furnace.

The regrinding of WWTF (example 9) leads to a decrease in the strength of the sinter due to the deterioration of the gas permeability of the sinter charge layer and overuse of coke.

Information sources

1. Copyright certificate No. 1529738, C 22 V 1/16, publ. 09/27/1995, BI No. 27.

2. Copyright certificate No. 1386668, C 22 V 1/16, publ. 1988, No. 13.

3. RF patent No. 2041964, C 22 V 1/24, publ. 08/20/1995, BI No. 23.

Claims (3)

1. A method of preparing for sintering an agglomeration charge, comprising dosing and introducing iron ore products, metal products of metallurgical production, flux and fuel into the mixture, mixing and pelletizing, characterized in that part of the iron ore products is introduced in the form of a concentrate of firing-magnetic enrichment of sideroplezite obtained after roasting sideroplezitic ore at 850-1050 ° С and dry magnetic separation of the calcined product in fields of 1000-1200 erst, mixed with circulating products of metallurgical productions in and iron ore concentrates in the ratio (0.08-0.20) :( 0.05-0.15): 1.00. 2. The method according to claim 1, characterized in that the concentrate of firing-magnetic enrichment of sideroplezite contains the following ingredients, wt.%: Fe total 47-52, Mg 10-14 oxide, Ca 2-5 oxide, Si 4-8 oxide, nitrous oxide Mn 1.0-2.0, Al oxide 1.5-1.8. 3. The method according to claim 1 or 2, characterized in that the concentrate of firing-magnetic enrichment of sideroplezite has mass fractions of fineness of more than 10 mm and less than 0.1 mm, respectively 0-10% and 35-50%.