RU2298584C2 - Briquette for smelting steel - Google Patents

Abstract

FIELD: ferrous metallurgy; briquetting and making use of iron-containing waste.

SUBSTANCE: briquette includes iron-containing waste of metallurgical process at the following ratio, mass-%: blast-furnace dust, 1-40; dust-like dolomite, 5-30; cement used as binder, 1-5 and dust of gas cleaning of electric steel making process, 40-80. Invention ensures increase of good-to-bad yield by iron by 0.1%.

EFFECT: enhanced mechanical strength of briquettes; utilization of steel making process waste.

Description

The invention relates to ferrous metallurgy, in particular to briquetting and the use of iron-containing waste.

It is known to use iron ore materials in the form of briquettes as a metal charge for steelmaking processes [1].

However, these briquettes are made from original raw materials - ore, sinter, pellets and do not involve the use of by-products of metallurgical production - slags, sludges and screenings.

There is also known a method of steel smelting in a converter, which includes introducing scrap metal into the converter, casting iron, blowing metal with oxygen, an additive of lime, and as a slag-forming material of iron-lime-magnesia flux [2].

Significant disadvantages of the invention are:

- the use of original material, significantly increasing the cost of steel;

- the use of bulk material increases the duration of the melting process and leads to an increase in the duration of the melting.

Also known is selected as a prototype [3] a briquette for metallurgical production containing oxidized iron-containing material, a carburizer, a binder, an alloying additive and a plasticizer, characterized in that it additionally contains crushed iron-carbon alloy and fluxing additive in the following ratio of components, wt.%:

oxidized iron material 5-57 carburizer 20-30 binder 10-20 dopant 1-15 ground iron alloy 1-30 fluxing agent 1-10

plasticizer - in excess of 100% in an amount of 0.1-0.5% by weight of the binder

A significant disadvantage of this briquette is:

- low concentration of iron in the iron-containing material, in connection with which the performance of the steelmaking unit during redistribution is reduced;

- low mechanical strength of the briquette in connection with the presence of plasticizer;

- low foaming properties of the briquette due to the poor combination of carbon and iron oxides in the briquette;

- low degree of dephosphorization;

- high briquette aggressiveness in relation to the lining of the furnace due to the lack of the required amount of MgO.

The desired technical results of the invention are:

- increased yield and increased productivity of the steelmaking unit;

- increase the mechanical strength of briquettes;

- recycling of production waste;

- ensuring an increase in foaming of slag and a decrease in emergency stops due to a decrease in radiation during electric arc remelting into water-cooled furnace elements;

- an increase in the degree of dephosphorization of steel;

- reduced wear on the lining of the furnace.

To do this, we propose a briquette for steelmaking, containing iron-containing metallurgical waste, including blast furnace dust, pulverized dolomite and cement as a binder, characterized in that the briquette additionally contains gas cleaning dust from electric steelmaking in the following ratio, wt.%:

gas treatment dust 40-80 blast furnace dust 1-40 dusty dolomite 5-30 cement 1-5

The claimed limits are selected experimentally. Due to the constituent oxides of calcium, magnesium, manganese, silicon, and ammonium oxides, gas treatment dust from the electric steelmaking production provides early slag formation and briquette dissolution (melting).

The iron oxides included in its composition provide, on the one hand, the most complete reduction of iron and, accordingly, increase the yield, on the other hand, provide the most optimal foaming of slag. At a concentration of less than 40%, the oxides contained in the briquette are insufficient for the successful formation of slag, and at a concentration of more than 80% the protective function of the briquette decreases due to the high FeO content in the slag and low MgO values.

The blast furnace dust is introduced as a component, including carbon, which is necessary for the operation of foaming slag in electric arc furnaces to protect water-cooled elements from heating when emitted from electric arc remelting. Moreover, with the introduction of more than 40%, strong carburization of the steel and a decrease in furnace productivity due to the oxidation of excess carbon introduced into the steel are possible, and when less than 1% of carbon is introduced, it is not enough for foaming slag.

Dusty dolomite is introduced into the briquette as a component containing MgO and contributes to the protection of the lining from corrosion, moreover, with an increase in the content of more than 30%, viscous non-reactive slag can be obtained, and with a decrease in the concentration of dusty dolomite less than 5%, the protective function of the lining is not provided when using the briquette .

Cement is used as a binder, and when using less than 1%, it will not be possible to obtain the required mechanical strength of the briquette, and with an increase of more than 5%, the unproductive costs of the production of briquettes increase and the formation of liquid slag is difficult.

The inventive briquettes were made of materials with the following chemical composition:

- gas treatment dust from electric steel production: 0.75-59% Fe ₂ O ₃ ; 9-51% FeO; 1-25% CaO; 2-22% MgO; 1-12% MnO; 0.2-6% Cr ₂ O ₃ ; 1-19.4% SiO ₂ ; 0.3-13% Al ₂ O ₃ ; 5.1-7.9% C; 0.20-0.28% P ₂ O ₅ ;

- blast furnace dust (blast furnace production): 38-43% FeO; 17-19% C; 5.0-6.1% CaO; 7.2-8.1% SiO ₂ ; 2.6-2.9% Al ₂ O ₃ ; 0.04-0.06% P ₂ O ₅ ; 0.3-0.4% MnO;

- pulverized dolomite: 85-90% MgO, 3-6% CaO, 2-4.5% SiO ₂ ;

- cement (grade M-500): 6.0-6.60% Al ₂ O ₃ ; 3-3.08% Fe ₂ O ₃ ; 0.20-0.39% FeO; 56.0-57.80% CaO; 3.0-3.4% MgO; up to 0.05% P ₂ O ₅ .

The above components were mixed, moistened and dried for at least three days. Briquettes were used in steelmaking in 100-ton electric arc furnace furnaces of the type DSP-100I7 and DSP-100N10.

The inventive briquette provided:

- increase in yield on iron by 0.1%,

- satisfactory physico-mechanical strength of the briquettes (compressive strength of at least 12 MPa, impact strength of 97.43-98.18%, density of 2.20-4.16 g / cm ³ ),

- disposal of steel production wastes,

- good foaming properties of the slag, which allowed to reduce downtime due to burnout of the panels by 0.002%,

- an increase in the degree of dephosphorization by 0.6%,

- increase the lining resistance (refractory consumption reduced by 0.05 kg / t).

Information sources

1. Ravich B.M. Briquetting of ores. - M .: Nedra, 1982. - 183 p.

2. RF patent No. 2164952, class. C21C 5/28.

3. RF patent No. 2183679, cl. С21С 5/52, С21В 3/00, С22В 1/24, 1/242.

Claims (1)

Briquette for steelmaking, containing iron-containing metallurgical waste, including blast furnace dust, pulverized dolomite and cement as a binder, characterized in that it additionally contains gas cleaning dust from electric steelmaking in the following component ratios, wt.%: Dust for gas treatment in electric steelmaking 40-80 Blast furnace dust 1-40 Dusty dolomite 5-30 Cement 1-5