RU2238329C1 - Method for washing of blast furnace hearth - Google Patents

Abstract

FIELD: ferrous metallurgy, in particular, melting of cast iron in blast furnaces.

SUBSTANCE: method involves using washing briquettes; charging washing briquettes into peripheral zone of furnace mouth, said zone being defined by radii 0.85-0.5 of radius of furnace mouth. Briquette contains following elements and oxides: C:Fe=0.05-0.15; Mn:Fe=0.03-0.2; CaO:SiO₂=0.6-1.2; MgO:Al₂O₃=0.2-0.6.

EFFECT: increased efficiency of blast furnace and reduced consumption of coke.

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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 washing the hearth of a blast furnace, including loading into the furnace a washing mixture consisting of welding slag and manganese ore [1]. The method provides an effective washing of the hearth from coke debris with ferromanganese slag formed from the washing mixture. The disadvantage of this method is the presence in the washing mixture of welding slag, which is absent in modern metallurgical plants with steel casting at CCM.

The closest in technical essence and the achieved result is a method of washing the hearth of a blast furnace by loading into the furnace a washing component of the charge - high-sinter agglomerate [2]. In this method, adopted as a prototype, eliminated the disadvantage of an analogue. Wash agglomerate can be produced at any metallurgical plant, which includes sinter plant. However, this method is not free from disadvantages. Periodic sintering of the washing agglomerate necessitates interchanges at the sinter plant and leads to the production of transition agglomerates, the composition of which differs from ordinary and washing agglomerates and its use in the charge of blast furnaces leads to fluctuations in furnace heating and composition of cast iron.

An object of the invention is to eliminate the disadvantages of the known methods - analogue and prototype, increasing the productivity of the blast furnace and reducing the consumption of coke.

The solution to this technical problem is achieved by the fact that in the known method of washing the hearth of a blast furnace, including loading the washing component of the blast furnace charge into the furnace, briquettes with the following ratios of the elements and oxides C contained in them are used as the washing component: Fe: 0.05 .. .0.15, Mn: Fe = 0.03 ... 0.2, CaO: SiО ₂ = 0.6 ... 1.2, MgO: A1 ₂ О ₃ = 0.2 ... 0.6 moreover, the loading of briquettes is carried out in the peripheral region of the top, limited by the radii of 0.85 ... 0.5 of the radius of the top.

The invention consists in the following. Maintaining the ratio of carbon and iron contents in the briquettes for washing the hearth of the blast furnace within the range of 0.05 ... 0.15 ensures the restoration in the briquettes, when they are in the blast furnace, of iron oxides of iron-containing materials to the degree of oxidation of wustite at various iron contents in the briquette . The lower limit refers to briquettes containing 35-45% Fe with an oxidation (atomic ratio O: Fe) of 1.35 ... 1.40, the upper limit refers to briquettes containing 45-55% Fe with an oxidation of 1.4 ... 1.50. A decrease in the C: Fe ratio below 0.05 reduces the coke savings obtained by using briquettes in blast furnace smelting. Exceeding the upper limit reduces the oxidizing potential of the glandular slag formed from the materials of the briquette, and reduces the efficiency of the use of briquettes for washing the hearth produced from such a mixture.

Maintaining the ratio of the contents of manganese and iron in the washing component of the charge - briquettes within the range of 0.03 ... 0.2 provides an increase in the fluid mobility and oxidizing ability of the slag formed from the materials of the briquette charge. In this case, the lower limit of this ratio refers to the cases of briquetting on furnaces smelting cast iron with a limited lower limit of manganese content. Exceeding the upper limit of this ratio is undesirable due to the excessive increase in coke consumption when using washing briquettes.

Maintaining the ratio of CaO: SiO ₂ and MgO: A1 ₂ O ₃ oxides in briquettes, respectively, in the range of 0.6 ... 1.2, 0.2 ... 0.6 ensures the formation of mobile ferrous aluminum-calcium briquettes from waste rock -magnesium silicate slag with a low crystallization temperature (1150-1200 ° C), which quickly drain into the furnace and oxidize coke breeze, which impairs the drainage capacity of the coke nozzle in the furnace. In this case, the lower limit of the CaO: SiО ₂ ratio corresponds to the upper limit of the MgO: A1 ₂ О ₃ ratio and vice versa. The lower limit of the MgO: A1 ₂ O ₃ ratio, in turn, corresponds to the increased alumina content in the resulting slags (10 ... 15%), 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 loading of the washing component of the charge - briquettes into the peripheral annular zone of the top, limited by the radii of 0.85 ... 0.5 of the radius of the top, ensures the efficient use of this component. The ferrous slags formed from briquettes flow down into the hearth zone, in which the so-called "bird's nest" is located - the zone with the maximum concentration of coke breeze.

The invention is illustrated by the following example. In a blast furnace with a volume of 1033 m ^3, upon detection of signs of deterioration in the drainage capacity of the coke nozzle and the removal of coke breeze at the furnace outlets, they were washed in accordance with the invention by loading washing briquettes into the annular area of the top of the furnace, limited by radii of 0.85-0.5 of the radius of the top. In the washing briquettes used for washing the hearth, the ratio of elements and oxides was C: Fe = 0.25, Mn: Fe = 0.07, CaO: SiO ₂ = 0.86, MgO: A1 ₂ O ₃ = 0.39. An increase in coke consumption and a decrease in furnace productivity during washing of the hearth according to the invention did not occur. Thus, the use of the invention allows you to effectively wash the hearth of blast furnaces from the accumulation of coke debris without compromising its performance.

Sources of information

1. USSR author's certificate No. 802365, MKI C 21 V 3/00, 1981.

2. Copyright certificate of the USSR No. 1620488, MKI C 21 V 3/00, 1991.

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

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

Claims (1)

A method of washing a furnace hearth of a blast furnace, comprising loading into the furnace a washing component of a blast furnace charge, characterized in that briquettes are used as a washing component of the mixture with the following ratios of the elements and oxides C contained therein: Fe = 0.05 ... 0.15, Mn: Fe = 0.03 ... 0.2, CaO: SiO ₂ = 0.6 ... 1.2, MgO: Al ₂ O ₃ = 0.2 ... 0.6, and the briquettes are loaded in the peripheral region of the top, limited by the radii of 0.85 ... 0.5 of the radius of the top.