RU2237723C1 - Method of blast-furnace smelting - Google Patents

Abstract

FIELD: ferrous metallurgy; blast-furnace process; making iron in blast furnaces.

SUBSTANCE: blast-furnace charge includes carbon-containing additives-briquettes manufactured from carbon-containing materials and natural or technogenic materials. Briquettes are charged in circular peripheral zone of furnace top bounded by radius of 0.4-0.9 of radius of furnace top. Briquettes contain the following elements and oxides: C:Fe=0.25-0.55; CaO:SiO2=0.3-1.6; MgO:Al2O3=0.25-1.25.

EFFECT: reduced consumption of coke; enhanced utilization of industrial wastes.

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Description

The invention relates to ferrous metallurgy, in particular to blast furnace production, and can be used in the smelting of pig iron in blast furnaces.

A known method of blast furnace smelting, including loading coke, iron ore materials, fluxing additives into the furnace, blowing heated oxygen-enriched blast and additional fuel into the furnace, loading solid carbon-containing additives into a certain annular top furnace [1]. The disadvantage of this method is that it provides for the loading of solid carbon-containing additives in the area transporting this additive to the area of the tuyere foci. This allows you to use according to this known method, only such carbon-containing additives that perform only some of the functions of solid fuel in blast furnace smelting (participation in the gasification reaction, burning in tuyere foci).

The closest to the invention in technical essence and the achieved results is a known method of blast furnace smelting, which includes loading iron ore materials, coke, blowing air and fuel additives into air lances, loading a carbon-containing additive into the annulus of the furnace top, limited by radii 0.1 and 0, 95 radius of the top. The disadvantage of this known method, adopted as a prototype, is that it uses a natural material - shungite as a carbon-containing additive, the use of pig iron in smelting is limited to 25-35 kg / t, the excess of which causes a decrease in the coke replacement coefficient with shungite and reduces the efficiency a known method of blast furnace smelting [2].

An object of the invention is to eliminate the disadvantages of the known methods of analogue and prototype, reducing the consumption of coke in blast furnace smelting, utilization of industrial waste carbon-containing materials.

The solution to this technical problem is achieved by the fact that in the known method of blast furnace smelting, which includes loading iron ore materials, coke, blowing blast and fuel additives into air lances, loading a carbon-containing additive into a given annular zone of the top, carbon-containing briquettes obtained are used as a carbon-containing additive from natural or man-made raw materials and containing carbon, iron, calcium, silicon, magnesium, aluminum oxides in the ratios C: Fe = 0.25 ... 0.55, CaO: SiO ₂ = 0.3 ... 1.6, MgO: Al ₂ O ₃ = 0.25 ... 1.25, respectively, Rich loading lead briquettes in the furnace top annular zone bounded by radii of 0.4 ... 0.9 the radius of the furnace top.

The invention consists in the following. The use of briquettes from natural or man-made raw materials containing carbon and iron oxides as a carbon-containing additive allows the use of small carbon-containing material, which in the composition of the briquette acts as a reducing agent. The ratio of carbon and iron contents in the range of 0.25 ... 0.55 provides 100% metallization of iron oxides of iron-containing materials at various iron contents in the briquette. The lower limit refers to briquettes containing 35-40% Fe with an oxidation (atomic ratio O: Fe) of 1.15 ... 1.25, the upper limit refers to briquettes containing 45-50% Fe with an oxidation of 1.4 ... 1.45. The lower limit also takes into account the carbon consumption for carburizing iron formed from iron-containing briquette materials. A decrease in the C: Fe ratio below 0.25 reduces the coke savings obtained by using briquettes as a carbon-containing additive in blast furnace smelting. Exceeding the upper limit leads to the formation of heterogeneous slag from gangue due to the introduction of unused coke or semi-coke particles into the slag. Heterogeneous slag has an increased viscosity, low fluidity and reduces the gas permeability of the lower part of the furnace both in the slagging zone and in the coke packing under the slagging zone, which leads to a decrease in furnace productivity.

Maintaining the ratios of CaO: SiO ₂ and MgO: Al ₂ O ₃ oxides in the briquettes, respectively, in the range of 0.3 ... 1.6 and 0.25 ... 1.25 ensures the formation of slag briquettes from the waste rock with a relatively low temperature crystallization (1300-1400 ° C), which dissolve in liquid ferrous primary slags formed from waste rock of other charge components (agglomerate and pellets). In this case, the lower limit of the CaO: SiO ₂ ratio corresponds to the upper limit of the MgO: Al ₂ O ₃ ratio and vice versa. The lower limit of the MgO: Al ₂ O ₃ ratio, in turn, corresponds to the increased alumina content in the resulting slag (15-25%), and the upper limit to the moderate alumina content in these slags (5-10%). The specified limits are selected on the basis of experimental data obtained in the study of crystallization temperatures and viscosity of synthetic and industrial blast furnace slags of various plants [3, 4].

The limitation of the peripheral zone of the top of the furnace, where the carbon-containing briquette additive is loaded, to the limits of 0.4-0.9 of the radius of the top of the furnace, eliminates the negative influence of slag formed from waste rock briquettes on the gas permeability of the lower zone of the furnace. The expansion of these limits towards the center of the furnace causes a slowdown in the dissolution of these slags in the mass of primary slag from the slag formation zone. The expansion of these limits in the direction of the periphery of the furnace causes the danger of dust formation with the participation of refractory slag from waste rock briquettes.

The invention is illustrated by the following example. In a blast furnace with a volume of 1033 m ^3, pig iron was smelted using sinter and pellets in the charge. The furnace operated on an oxygen-enriched blast with natural gas injection. According to the invention, a carbon-containing additive in the form of sludge-coke briquettes made of steel smelting sludge and coke breeze using a cement binder was introduced into the mixture. Briquettes were loaded into the peripheral zone of the top, limited by the radii of 0.5-0.8 radius of the top. The composition of the briquettes was characterized by the following ratios of elements and oxides: C: Fe = 0.39, CaO: SiO ₂ = 1.54, MgO: Al ₂ O ₃ = 0.36. The resulting briquettes had high strength and their use in the blast furnace charge did not cause complications. As a result of the melting of an experimental batch of 2000 tons of briquettes with an average consumption of 120 kg / t of cast iron, coke consumption was reduced by 23 kg / t.

Thus, the blast furnace smelting method according to the invention allows smelting cast iron with a reduced coke consumption due to its partial replacement with a carbon-containing additive in the form of briquettes made using carbon-containing waste and natural or man-made iron-containing raw materials. This solves the problem of recycling industrial waste.

Sources of information

1. RF patent No. 2042714, MKI C 21 V 5/00, the application. 06/26/1993, publ. 08/27/1995, Bull. Number 24.

2. RF patent No. 2186855, MKI C 21 V 5/00, the application. 04.24.2001, publ. 08/10/2002, Bull. No. 22.

3. Blast furnace production. Handbook t. 1. - M .: Metallurgy, 1989, p. 358 and 359.

4. Slag regime of blast furnaces. - M .: Metallurgy, 1967, p.149-157.

Claims (1)

A blast furnace method comprising loading iron ore materials, coke into a furnace, blowing blast and a fuel additive into air tuyeres, loading a carbon-containing additive into a given annular top zone, characterized in that carbon-containing briquettes obtained from natural or man-made raw materials are used as a carbon-containing additive containing carbon, oxides of iron, calcium, silicon, magnesium, aluminum in the ratios C: Fe = 0.25-0.55, CaO: SiO ₂ = 0.3-1.6, MgO: Al ₂ O ₃ = 0.25 -1.25, respectively, and the briquettes are loaded into the annular zone top, limited to radii of 0.4-0.9 radius of the top.