RU2493271C1 - Briquette for production of cast iron and steel - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: briquette includes steel scale, broken electrodes as carbon-containing material, mixture of silicon dioxide, natron and aluminium oxide as binding substance, also it includes dry slurry of gas cleaning of electrical steel furnaces at the following ratio of components, wt %: broken electrodes 9-21, dry slurry of gas cleaning of electrical steel furnaces 10-15, mixture of silicon dioxide, natron and aluminium oxide 1-10, steel scale - the rest. Mixture of silicon dioxide, natron and aluminium oxide contains 3-18 wt % of aluminium oxide , 14-25 wt % of natron, silicon dioxide - the rest.

EFFECT: high mechanical strength of briquette.

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Description

The invention relates to metallurgical production, and in particular to the preparation of charge materials for smelting cast iron and steel.

A known briquette for metallurgical production (RF patent, No. 2352648 IPC C22B 1/243, publ. 04/20/2009, Bull. No. 11), which contains metallurgical scale and electric furnace dust as iron-containing materials, coke breeze as a carburetor, and refining slag as a binder.

The disadvantage of the briquette is the use of refining slag, which is added in large quantities, and does not provide sufficient strength necessary for transportation and storage.

A well-known briquette proposed by OJSC "Novokuznetsk Metallurgical Plant", from dross of ferrous metals, blast furnace dust, dust gas treatment of electric steelmaking and cement as a binder (RF patent No. 2304175, IPC C22B 1/243, publ. 08/10/2007, Bull. No. 22 )

The use of cement as a binder does not provide the mechanical strength of the briquette in the conditions of melting in a metallurgical unit.

Closest to the invention is a briquette for the production of iron and steel (RF patent No. 2083681, IPC C21C 5/06, C22B 1/24, 1/242, publ. 07/10/1997, Bull. No. 19). The briquette contains steel oxide, carbon-containing material and a binder. The disadvantage of the briquette is the use of liquid glass, the use of which leads to cracking of the briquette after drying and a decrease in strength.

The technical result of the invention is to obtain a briquette with high mechanical strength, which allows to utilize the waste of metallurgical production.

The specified technical result is achieved in that the briquette for the production of cast iron and steel, including steel oxide, electrode bout as a carbon-containing material and a mixture of silicon dioxide, sodium oxide and aluminum oxide as a binder, additionally contains dry sludge for gas treatment of electric arc furnaces, in the following ratio of components , wt.%:

Electrode battle 9-21 Dry sludge gas treatment electric furnace 10-15 A mixture of silica, sodium oxide and alumina 1-10 Steel scale rest

The dry sludge from the gas treatment of electric steel furnaces has the following composition,%: FeO 4.80, Fe ₂ O ₃ 52.00, SiO ₂ 7.80, Al ₂ O ₃ 1.10, CaO 5.80, CaF ₂ 4.50, P 0.046. This waste is not used in industry and, accumulating in dumps, leads to environmental pollution. The introduction of electric smelting furnaces into the dry sludge gas treatment mixture allows increasing the briquette strength after pressing and drying due to sintering of sludge particles with particles of steel scale after firing. The introduction of dry sludge from gas treatment of electric arc furnaces in an amount of less than 10% does not provide sufficient briquette strength, and more than 15% leads to the formation of a large amount of slag when using a briquette, which worsens the smelting process.

The introduction of a mixture of aluminum oxide, sodium oxide, silicon dioxide, less than 1% does not provide sufficient strength, and more than 10% reduces the content of steel scale and electrode battle, which reduces the yield of metal when using a briquette.

As a carbon-containing material, the briquette contains 9-21% of the electrode battle. The introduction of briquette electrode combat in an amount of less than 9% does not provide the necessary degree of iron reduction, and more than 21% leads to a decrease in the mechanical strength of the briquette and is not economically feasible. The use of electrode combat can reduce the amount of sulfur and phosphorus introduced by carbon-containing material.

As an iron-containing material, steel scale of the composition was used,%: Fe _total 72.49, FeO 56.30, Fe ₂ O ₃ 41.00, P 0.009, S 0.008. The low content of sulfur and phosphorus in the iron-containing material, which is part of the briquette, can improve the quality of cast iron and steel by reducing the content of harmful impurities.

The manufacture of briquettes is as follows.

Steel scale of a fraction of 0.6-3.0 mm, dry sludge for gas treatment of electric furnaces of a fraction of less than 0.1 mm and an electrode battle of a fraction of less than 0.3 mm were mixed. Separately, a mixture of silica, alumina, sodium oxide, 0.1 mm fraction was prepared in the following percentage, wt.%:

Aluminium oxide 3-18 Sodium oxide 14-25 Silica rest

These components were mixed together, moistened before pressing, based on the ratio of 5-10 ml of water per 100 g of the mixture (in excess of 100% of the mixture weight).

Adding less than 5 ml of water to the mixture leads to insufficient moisture and poor extractability of the briquette from the mold, and more than 10 ml leads to excess moisture and an increase in drying time to remove it from the briquette.

The resulting mixture is pressed in the form of bodies of arbitrary shape with a pressing pressure of at least 35 MPa. The finished briquettes are dried for 1-2 hours at a temperature of 150-200 ° C, burned in an oven for 0.5-1.0 hours at a temperature of 800-1000 ° C and cooled in air.

Example. The composition of the briquettes is given in table 1.

Table 1 The composition of the briquettes Components The content of components in the composition of the briquette, wt.% one 2 3 four 5 Dry sludge gas treatment electric furnace 8 10 12 fifteen 17 Electrode battle 3 9 fifteen 21 27 A mixture of oxides Al ₂ O ₃ , Na ₂ O, SiO ₂ 0.5 one 5 10 fifteen Steel scale 88.9 80 68 54 41

Cylindrical briquettes were subjected to mechanical tests. The compressive strength was determined by crushing the briquettes in a hydraulic press. The test results of the strength of the briquettes in compression (which is the average of three experiments for each of the compositions) and the density of the briquettes are presented in table 2.

table 2 Mechanical properties of briquettes of various compositions Composition number Compressive Strength, MPa (kgf / cm ² ) Density, kg / m ³ one 312 2564 2 374 2653 3 423 2685 four 385 2498 5 338 2785 Prototype (a.s. No. 2083681) 358 2890

As can be seen from table 2, the proposed briquettes have sufficient density and higher strength than the prototype.

Briquettes of cylindrical shape with a diameter of 25 mm and a height of 20 mm were melted in alundum crucibles placed in a Tamman furnace. The results of experimental swimming trunks conducted using briquettes are shown in table 3.

Table 3 The chemical composition of cast iron and steel smelted using briquettes Chemical composition, % C Si Mn P S Briquettes smelted cast iron 4.17 0.20 0,03 0.018 0.024 Briquetted steel 0.11 0,03 0.01 0,021 0.007

As can be seen from table 3, the chemical composition of the obtained cast iron is characterized by a low content of harmful impurities. The steel, smelted using briquettes, in chemical composition corresponds to carbon-grade structural steel 08kp.

Thus, the claimed composition of the briquette provides high mechanical strength, does not contain expensive and scarce components, and also allows the use of production waste.

Claims (1)

A briquette for the production of cast iron and steel, including steel oxide, electrode fight as a carbon-containing material and a mixture of silicon dioxide, sodium oxide and aluminum oxide as a binder, characterized in that the briquette additionally contains dry sludge for gas cleaning of electric steel furnaces in the following ratio of components, wt. %: electrode battle 9-21, dry sludge from gas treatment of electric arc furnaces 10-15, a mixture of silicon dioxide, sodium oxide and aluminum oxide 1-10, steel oxide - the rest.