RU2410447C1 - Mix material for production of manganese-containing staflux - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy, particularly, to production of complex manganese-containing staflux for blast furnaces. Mix material intended for producing staflux with balimestonesicity (CaO/SiO₂) of 4.5-8.5 and iron content not lower that 40%, consists of limestone, solid fuel, low-silicon iron-containing material in the form of the mix of metallurgical wastes of 0-5 mm-fineness and manganese-containing component in the form of carbonate ore with manganese content of 7.0-9.0 %. Ratio of components in mix material is as follows, in wt %: limestone - 12.0-20.0; manganese-containing carbonate ore - 8.5-12.0; solid fuel - 3.5-7.0; low-silicon iron-containing mix making the rest. Mix of sinter waste, aspiration and blast-furnace dust and slags are used as low-silicon iron-containing mix.

EFFECT: high-strength high-basicity manganese-containing flux with increased content of iron and basicity that add to blast furnace efficiency.

2 cl, 3 tbl, 2 ex

Description

The invention relates to ferrous metallurgy, and in particular to the production of complex manganese-containing iron flux for blast furnaces.

A known mixture for the production of iron flux, consisting of a mixture of limestone, oily sludge from the secondary sumps of the recycling water system of the rolling shops, lump of lime and fluorspar, with the following ratios of components, wt.%:

limestone 60.0 dry sludge 33.0 lime 6.0 fluorspar 0.74 heavy carbohydrates childbirth (oil) 5,0

The disadvantages of this composition of the charge is the low productivity of the hot pelletizing unit in the production of iron flux due to the low lime content and poor quality of the finished product.

A mixture is also known for the production of iron flux, which includes steelmaking slag and sludge, blast furnace slag, blast furnace and converter dust, scale, sinter and pellet screenings, lime and fluorspar (ed. Certificate of the USSR No. 765370, class C21C 5/28 , C22B 1/16, 1980).

A known mixture for flux, which contains,%: lime 15-20, limestone or dolomite 10-12, fuel 8-10, converter sludge or scale - the rest (ed. Certificate of the USSR No. 945209, class C21C 5/00, 1982). The disadvantages of these blends are the high contamination of iron flux with harmful impurities, its low refining ability.

There is a known (author. Certificate of the USSR No. 1254021, MKI C21C 5/36, publ. BI No. 32, 1986, prototype) a method for producing flux by heat treatment of a mixture of limestone and iron flux using gaseous fuels in rotary kilns.

The mixture consists of limestone and ferrite additives, in which the molar ratio Fe ₂ O ₃ / CaO = 2-3, the content of SiO ₂ is 1-3%, and its mass is 20-30% of the total mass of flux loaded into the furnace. As a ferrite additive, in particular, sludges from steelmaking can be used.

The disadvantage of the mixture is that due to the low iron content (2.76-10.1 Fe _total ) and high CaO content (81-85%), the resulting flux is suitable only for use in the converter industry. Attempts to increase the iron content in the flux by increasing the additive of ferrite additives did not give the desired result, since the use of multicomponent charge with different density components in rotary kilns is associated with great difficulties.

Known ferrite-calcium flux (RF patent No. 2087557, MKI C22B 1/16, published in BI No. 23, 1997), including iron-containing waste or a mixture of waste, limestone, dolomite and fuel. Moreover, the iron-containing waste and their mixture are characterized by the ratio Fe / SiO ₂ ≥11, and the content of SiO _{2 is} limited to the range of 0.5-5.0% (wt.). The production of ferrite-calcium flux from the specified mixture is carried out on tape sinter machines. The method allows to obtain a ferrite-calcium flux with a high iron content (Fe _total. ≥50%, 11-18 CaO and 3.5% SiO ₂ ), suitable for use in a blast furnace process.

Known mixture for producing highly basic manganese-containing agglomerate containing manganese raw materials, solid fuel and flux, according to the invention, it additionally contains iron ore concentrate in the following ratio of components, wt.% (And.with. No. 1446181, class C22B 47/00, publ. 12/23/1988, BI No. 47):

flux 35-60 iron ore concentrate 6-20 solid fuel 8-15 manganese raw materials - the rest

A disadvantage of the known technical solutions is the low mechanical strength of the obtained product and low moisture resistance.

The closest analogue of the claimed technical solution is a known method for producing a manganese-containing complex flux, including dosing, mixing, granulating a mixture consisting of limestone, solid fuel, manganese-containing raw materials (AS No. 1708893, С22В 1/24, publ. 30.01.1992, Bulletin No. 4), in addition, an iron-containing material is additionally introduced into the charge, for which converter sludge is used, and ferromanganese waste is used as the manganese-containing material. Experience in the production of flux according to the proposed technology showed that it is not possible to avoid the formation of refractory dicalcium calcium silicate with a melting point of more than 2100 ° C due to close contact of fuel ash (SiO ₂ ) and CaO particles. Due to the formation of 2CaOSiO _{2, the} quality of the flux deteriorates, its viscosity decreases. In addition, such a manganese-containing flux has a low basicity.

The technical result of the invention is to obtain a strong highly basic manganese-containing flux with a high iron content and high basicity, contributing to the formation of fluid slag, as well as improving the technical and economic indicators of blast-furnace smelting.

The technical result is achieved by using a charge for the production of manganese-containing iron flux with a basicity (CaO / SiO ₂ ) of 4.5-8.5 and an iron content of at least 40%, consisting of limestone, solid fuel, low-silica iron-containing material in the form of a mixture of metallurgical wastes with fineness 0-5 mm and a manganese-containing component in the form of carbonate ore with a manganese content of 7.0-9.0%, with the following components, wt.%:

limestone 12.0-20.0 manganese-containing carbonate ore 8.5-12.0 solid fuel 3.5-7.0 low siliceous iron mixture - the rest,

in this case, as a low-silica iron mixture, a mixture of sintering, suction and blast furnace dust and sludge is used.

The invention proposed for patenting consists in the use of a mixture for the production of manganese-containing iron flux, in which, along with manganese-containing carbonate ore, low-silicon iron-containing metallurgical wastes are used that form an iron-containing mixture. The limited content of silica eliminates its harmful effect on the impregnation of limestone with iron oxides, since in this case the possibility of formation of a refractory dicalcium silicate (t _pl. = 2130 ° C) is minimized, which covers the pieces of lime with a shell and inhibits the diffusion of iron oxides into pieces . In addition, the presence of 2CaO SiO ₂ promotes the formation of deposits in the blast furnace.

A low-silica iron mixture is prepared from metallurgical waste by mechanical mixing of the components. The size of the iron-containing mixture is in the range of 0-5 mm. The improvement of the physico-mechanical properties of iron flux is facilitated by the uniform distribution of preformed ferritic and other ligaments. For a uniform distribution of the iron-containing mixture, the size of its components should be comparable with the other components of the mixture, i.e. 0-5 mm.

The use of a low-siliceous iron-containing mixture and manganese-containing carbonate ore contributes to the formation of a low-melting highly active iron-calcium flux with an Fe content of more than 40% and a basicity (CaO / SiO ₂ ) in the range of 4.5-8.5 and without additional use of iron-containing and carbonate fluxes VI suitable in blast furnace production.

Limits of limestone content are determined by the quality of cast iron and the consumption of coke for its production. When the limestone content in the mixture of iron flux is less than 12%, the iron produced in the blast furnace does not meet the requirements of the steelmaking for sulfur content. When the limestone content in the mixture is more than 20%, the consumption of coke in the production of cast iron increases.

The limits of solid fuel content are determined by the task of obtaining a solid iron flux. When the solid fuel content in the charge is less than 3.5%, the strength of iron flux does not meet the requirements of blast furnace production. When the solid fuel content in the charge is more than 7.0, coke consumption increases, without a significant increase in the strength of iron flux.

The introduction of manganese carbonate ore into the mixture within the specified limits (8.5-12.0%) allows to intensify the sintering processes of iron flux by accelerating the dissolution of calcium, manganese and magnesium oxides, and contributes to their assimilation by a manganese-containing melt. The limits of carbonate ore content are due to the need to obtain a mass fraction of Mn in the finished iron flux of at least 1.0% with a tolerance of ± 0.3%.

The presence of iron in the low-silica iron mixture leads to the formation of low-melting eutectics of calcium, manganese and magnesium ferrites. In this case, the phase formations in the Mn-Fe-Ca-Mg system are stabilized and, thereby, phase transformations that lead to the destruction of iron flux are reduced.

The use of a low-silicon iron-containing mixture in predetermined limits with an iron content of at least 40% contributes to the production of iron flux with high strength characteristics.

The high specific surface of iron-containing metallurgical wastes (4.0-8.5 m ² / g) improves the granulation efficiency and helps to intensify the sintering process of the flux, and the intense formation of CaO and Fe ₂ O ₃ when heating the iron-containing mixture is accompanied by a uniform temperature distribution in the sinter layer, improving physicochemical properties and increasing the mechanical strength of sintered manganese-containing iron flux.

Example 1

On the basis of metallurgical waste: sintering, suction and blast furnace dust and sludge with a flow rate of the components of the raw materials indicated in table No. 2, a low-silica iron mixture was obtained by mechanical mixing, which was pumped into the selected bins.

Limestone, a manganese-containing component and solid fuel were also pumped into separate bins for their accurate dosage.

Further, components from the bunkers were dispensed 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 mixer and placed on sintering machine pallets for sintering, the layer height was 320-340 mm. Sintering was carried out at a temperature of 1250 ° C. After cooling, the sintered iron flux was subjected to drum tests to determine mechanical strength. Strength was evaluated by the yield of fractions of more than 5 mm, characterizing the index of resistance to fracture.

When conducting experimental work on testing the technology for obtaining the optimal mixture of iron flux for blast furnaces, the sintering indices of the known charge and charge, taken as a prototype, proposed as a new technical solution were compared.

Table No. 1 shows the comparative indicators of different charges. The combination of the above technological factors contributes to the production of manganese-containing iron flux durable in fur. properties and with high consumer properties, contributing to a significant increase in the technical and economic indicators of blast furnace smelting. Chem. the composition of the components of the charge of manganese-containing iron flux is shown in table No. 2.

The pilot testing of the patented manganese-containing iron flux was carried out on a blast furnace No. 5 of the Nizhny Tagil Metallurgical Combine (NTMK) with a useful volume of 2200 m ³ smelting vanadium-containing cast iron.

The existing NTMK technology for blast-furnace smelting of titanomagnetites provides for the use of about 40% of highly basic sinter (CaO / SiO ₂ = 2.2) and about 60% of non-fluxed pellets with a natural base of about 0.3 in the iron ore part of the charge. Vanadium cast iron contains an average of 0.07 - 0.08% silicon and about 0.35% manganese. Due to the fact that the basicity of slag (CaO / SiO ₂ ) is set within the range of 1.20-1.25, the consumption of limestone in the charge is about 60 kg / t of pig iron, and the increased consumption of limestone in blast furnace smelting leads to an increased consumption of coke.

Example 2

Consider an example of the specific use of patented iron flux in blast furnace smelting.

Manganese-containing iron flux coming from the sinter plant of the Vysokogorsky GOK was discharged to a separately allocated place in the ore yard of the blast furnace with the aim of cooling it for 2-4 days.

Weighted Chem. the composition of iron flux specified in table No. 2, met the requirements of the technical conditions for this material. Zhelezoflyus was used in the charge of blast furnace No. 5 by loading it into the furnace through the additive hopper. The consumption of iron flux was about 10% of the entire iron ore part of the charge and was adjusted according to the required basicity of slag. Moreover, sintering, limestone and manganese sinter were completely removed from the mixture. Zhelezoflyus was loaded into the skip together with pellets.

The loading parameters of the charge, the blast regime, the intensity of blast furnace smelting were maintained within the limits ensuring a smooth operation of the furnace, normal thermal state and optimal slag mode according to the factory instructions TI-102-132-2007.

Analysis of technological performance indicators of blast furnace No. 5, smelting vanadium cast iron, is shown in table No. 3.

A feature of the smelting of vanadium cast irons is the formation of titanium carbides and carbonitrides in the furnace, the formation of which occurs even during the cold course of the furnace. At the same time, losses of cast iron with carbides and carbonitrides reach 10-15%.

Patented iron flux helped to improve the process of slag formation in the furnace and reduced the viscosity of the final blast furnace slag, due to which an improvement in the separation of smelting products at the outlet from the furnace was achieved and losses of cast iron with slag were significantly reduced. The decrease in the viscosity of blast furnace slag occurred due to the lesser formation of titanium carbonitrides and grenal in the furnace, due to the favorable chemical composition of iron flux, its low melting point (1260-1280 ° C), and good fluid mobility in the molten state.

The slag viscosity decreased from 0.29 to 0.22-0.24 Pa · s, which ensured a decrease in the concentration of metal in the slag at the outlet from the furnace, as mentioned above, by 10-15%.

This factor contributed to an increase in the production of pig iron by the day in pilot melts from 5,235 tons to 5,810 tons (by 9.8%).

Through the use of manganese-containing iron flux proposed for patenting, it was possible to achieve:

- specific consumption of coke decreased by 10 kg / t of pig iron, while in the experimental period, the consumption of natural gas was lower by 6 m ³ / t of cast iron;

- raw limestone, sieve of KGOK agglomerate and manganese sinter of VGOK are completely removed from the mixture;

- the vanadium content in cast iron increased from 0.398% to 0.430%, and the vanadium extraction coefficient (CIV) increased from 81% to 85%;

- improved stability of the slag basicity (CAO / SiO ₂ ), and also became more stable chemical. the composition of cast iron by the content of V, Si, Mn;

- the sulfur content in cast iron remained unchanged.

Thus, the proposed technical solution fully meets the criterion of "novelty." The analysis of patents and scientific and technical literature did not reveal the use of new significant features used in the proposed invention for its functional purpose. Therefore, the present invention meets the criterion of "inventive step".

Table number 1 The performance of the sintering process of manganese-containing iron flux of different charges Indicators Manganese-containing iron flux Famous (prototype) Proposed The height of the layer of the charge, mm 750 320 Manganese-containing charge component,% 9.40 9.00 Solid fuel content in charge,% 6.93 5.8 Basicity (CaO / SiO ₂ ), units 3.73 7.5 Yield,% 78.0 80.5 Strength, fr.> 5 mm,% 94.0 92.4 Specific productivity, t / m ³ hours. 0.49 1.30 The content of Mn in iron flux,% 5.85 1,1

table 2 The chemical composition of the components of the charge blast furnace flux Charge Raw materials, t.t. Component Consumption per 1 t. of iron flux The content of iron flux components, % Fe CaO SiO ₂ S TiO ₂ MgO Al ₂ O ₃ Zn Mn V ₂ O ₅ Limestone 6.86 0.460 0.00 53.80 1.30 0.04 0.00 0.45 0.00 0,0 0,0 0.00 Aglootsev 6.90 0.457 54.30 10.50 4.70 0.16 2.41 2.40 2,50 0.10 0.16 0.51 Ash 0.13 0.009 10.00 6.00 42.00 0.00 1.00 1.40 26.60 0.00 0.00 0.00 Manganese Arbonate ore 2,31 0.154 0.00 41.00 6.94 0.05 0.00 1.33 1.46 0.00 9.00 0.00 Aspiration. dust 0.54 0,036 56.00 4.20 3.20 0.17 1.20 1.30 1,50 0.10 0.18 0.19 Blast furnace dust 1.21 0,081 43.00 6.10 4.85 0.23 1.00 2.20 2.82 0.25 0.40 0.40 Sludge 2.63 0.175 55.00 4.00 3.00 0.14 0.55 2.00 1,50 1,63 0.50 0.41 Weighted average composition of iron flux 43.02 25.77 5.58 0.08 0.85 1.48 2.15 0.09 1.10 0.32

Performance indicators of NTMK blast furnace No. 5 using conventional technology and using iron flux.

Conventional technology Using iron flux Production at the workshop (days), tons 5235 5810 The composition of the mixture,%: agglomerate KGOK 35 36 KGOK pellets 60 54 sintering sifter 5 - iron flux - 10 The Fe content in the HR part of you, %: 57.6 59.3 Total Fe Consumption, kg / t 988.0 982,2 Fe consumption in iron ore, kg / t 977.0 969.5 GHG consumption, cubic m / t 115.5 117.0 Consumption, kg / t: coke 422 405 Iron ore 1665 1527 Additives, kg / t: limestone 66.0 0 Marg agglomerate VGOK 5,0 0 Blast: pressure, atm. 3.67 3.61 temperature, ° С 1187 1221 The content of O ₂ in the blast,% 25.0 22.7 Consumption of O ₂ , cubic / ton of cast iron. 60.61 62.90 Chem. composition of cast iron,%: Si 0,07 0.08 Mn 0.31 0.31 S 0.018 0.018 V 0.398 0.430 Ti 0.14 0.15 Slag basicity, units 1.25 1.23 The content of V ₂ O ₅ ,%: sinter. KGOK 0.498 0.513 okat. KGOK 0.556 0.564 iron flux - 0.32 KIV,% 80.76 84.96 Downtime,% 1.8 0

Claims (2)

1. The mixture for the production of manganese-containing iron flux with a basicity (CaO / SiO ₂ ) of 4.5-8.5 and an iron content of at least 40%, consisting of limestone, solid fuel, low-silica iron-containing material in the form of a mixture of metallurgical waste with a particle size of 0-5 mm and a manganese-containing component in the form of a carbonate ore with a manganese content of 7.0-9.0%, in the following ratio of components, wt.%:
limestone 12.0-20.0 manganese-containing carbonate ore 8.5-12.0 solid fuel 3.5-7.0 low siliceous iron mixture rest 2. The mixture according to claim 1, characterized in that as a low-siliceous iron-containing mixture, a mixture of sintering, suction and blast furnace dust and sludge is used.