SU918310A1 - Method for producing steel in open-hearth furnace - Google Patents

Description

(54) METHOD OF MANUFACTURING STEEL IN MARTENOV FURNACE

one

The invention relates to ferrous metallurgy, in particular to methods for the production of steel in main open-hearth furnaces.

A method of steel production in open-hearth furnaces is known, which includes the pure boiling of the metal, the supply of fuel, the shutdown of the fan air supplied to the working space of the furnace through regenerators, the reduction of fuel consumption, the introduction of ferroalloys into the metal into its release from the Ul 1 furnace.

However, this method of tolyso somewhat reduces the oxidative potential, the furnace and does not eliminate the leakage of air into its working space. The method also does not provide for the acceleration of the reactions of diffusion deacidification of the bath.

The closest in technical essence and access to the proposed result is the method of steel production in open-hearth furnaces, including the pure boiling of the metal.

fuel supply, shutdown of fan air supplied to (furnace's auxiliary space through regenerators, input of ferroalloys to the metal and its release from the furnace, simultaneously with switching off the fan air, stop the supply of fuel and introduce into the working space of the furnace countercurrent flows preheated in the regenerators of neutral or inert gas as well

Before entering the ferroalloys, the slag is treated with a deoxidizing mixture, by blowing the metal with a neutral or inert gas, and the amount of gas supplied through the regenerators is reduced to non-.

) S face, equal to the amount of gas injected into the metal, maintaining the total gas flow at a level that provides a positive pressure in the working space of the furnace 12.

Claims (2)

However, a high consumption of neutral or inert gas increases the cost of the steel produced. A significant decrease in temperature in the working space of the lechi reduces the effect of refining, deoxidation and alloying of the steel bath. The aim of the invention is to reduce the consumption of neutral or inert gas and maintain a higher temperature in the working space of the furnace. The goal is achieved by the method of steel production in open-hearth nets, including pure boiling of the metal, slag treatment with a deoxidizing mixture while simultaneously blowing the metal with a neutral or inert gas, introducing ferroalloys into the metal, adjusting the composition of the gas phase and pressure in the working spaces of the furnace and releasing metal, before the slag is treated with a deoxidizing mixture, counter flows of fan air are introduced into the working space of the furnace through the regenerators and at the same time begin to enter the neutral or inert gas, continuously increasing its quantity in the blast and reducing the amount of fan air by the same amount, completely stopping its flow just prior to the introduction of ferroalloys into the metal, and from the beginning of the treatment of slash with a deoxidizing mixture to the introduction of ferroalloys into the metal In the working space of the furnace, fuel is supplied in an amount of 1, O5 - 1.1 times the stoichiometrically necessary in relation to the free oxygen content in the gas phase of the furnace. The simultaneous introduction into the working space of the furnace of counter-current flows of a mixture of fan air and neutral gas provides the possibility of reducing the flow rate of the deficient neutral (inert) gas. The amount of neutral (or inert) gas in the blast evenly and continuously increases the value of the gas to a full transition to the neutral blast immediately before the introduction of ferroalloys into the metal. This ensures a uniform and continuous decrease in the iftie of the oxidation potential of the gas phase of the working area of the furnace during the period of slag treatment with a souring mixture. As the metal - slag system approaches equilibrium, the Bosstans & s rate of iron from slag oxides decreases, ceteris paribus. In this connection, a continuous decrease in the oxidation potential of the furnace goz phase ensures a continuous decrease in the content of ferrous oxide in the slag. THAT is especially important at low concentrations (3-5%) ferrous oxide in the slag. The presence of a certain amount of free oxygen in the blast before lowering into the working space of the furnace and simultaneously supplying fuel to the sing provides a higher temperature of the working space and a decrease in the oxidizing potential of its gas phase. The fuel is fed in an amount of 1, O5 - 1.1 times the stoichiometrically necessary in relation to the content of free oxygen in the gas phase of the furnace. The excess fuel ratio is within 1, O5 - 1.1. An increase in this ratio of 1.1 is impractical because it leads to unnecessary loss of fuel to the environment 6 in the form of products of its incomplete combustion and does not provide a further increase in the temperature level in the furnace working space. When the fuel excess ratio is less than 1.05 against the theoretically necessary fuel for complete combustion, it does not allow for the presence of some amount of free oxygen in the gas phase of the furnace working space due to imperfect mixing processes and mass exchange of fan air, neutral gas and fuel. During the period when the fuel is supplied to neutralize the free oxygen of the gas phase, water vapor forms in the furnace, since hydrogen and some moisture are always present in the fuel. For this reason, during the period of steel alloying, there is a danger of a significant transition of hydrogen from the gas phase through the slag to the metal. The complete cessation of the supply of fan air and the appropriate amount of fuel and the transition to a 100% neutral blast just before entering ferroalloys provides a significant reduction in the partial pressure of water vapor in the furnace working space and the production of steel with low hydrogen content. In a 50-gtonny main open-hearth furnace, heated by fuel oil and operating scrap metal, load 20 tons of pig iron, 30 tons of metal ohm to 4 tons of limestone. By melting, contains: it,%: C 0.9; Mvi 0.15; 5 q.OBO; PO, O2O; 5i traces. One ton of iron ore is planted and 8O% of primary slag is downloaded, after which a new slag is introduced, loading 1 ton of lime and 0.15 ton of fireclay gas. With a carbon content of about 7%, the bath goes to a clean boil. At the end of pure boiling, the metal contains,%: C 0.4; .MviO, 2; 9 0.025; P 0.015. Blowed into the bath 4OO kg of ground electrode bo and get in the metal 1% carbon. Slag after carburizing metal contains 6% Fe O and 2%,. During this period, the first furnace head is working and the combustion products go from right to left. I Before the treatment of slag races, the acid mixture is transferred to a two-way transfer of fan air through the left and right air regenerators into the working space of the furnace. Fuel oil is also fed to the left and right nozzles in an amount that is 1.1 times greater than the free oxygen content in the gas phase of the furnace working space (the oxygen content is recorded using test equipment). The pressure in the working space of the furnace is maintained at a level of 2-2.5 m water column. The flow rate of the fan air is set at about 3 m / min. The total flue damper from this period is down to the lower end position. A mixture of lime, fluorspar and aluminum in the amount of 250 kg is set on the slag and simultaneously supply nitrogen to the common furnace borehole for 10 minutes with a continuous increase in its flow rate to 3 and a corresponding decrease in the fan air flow rate, maintaining the total flow rate to blow at 3 m / min 5 min after the introduction of the deoxidizing mixture, the metal is purged with argon with an intensity of 0.02 · min for 5 min. The flow rate of the blow is reduced by an amount equal to the flow rate of argon. After ten minutes of slag treatment, they are transferred to a nitrogen blast, they are placed in a bath of 1050 kg of ferrochrome, the metal is kept in the furnace for 10 min, and released into the ladle while keeping, in%: C 1.0; Mm1.0, S-) 0, C 1.85; S Oh, 1O, RO, 020. After the release of melting, the supply of nitrogen to the furnace working space is stopped and transferred to the usual thermal conditions of the refueling period. The method reduces the consumption of nitrogen (or argon) on average from 3 to 2.2 or 0.32 steel. 10c. In this case, when using nitrogen, O, 32 O, O16 rubles / ton is saved, and when using argon, 1.5X0.32 0.48 rubles / ton, where 0, O5 and 1.5 are the cost of nitrogen and argon respectively rub / m A higher temperature in the working space of the furnace provides increased reactivity of the slag, which reduces the duration of the deoxidation period, resulting in an increase in furnace productivity by an average of 2% and a decrease in conditionally constant redistribution of redistribution. by 0.28 rubles per ton, as well as production of steel with a lower sulfur content. The expected economic effect from the implementation of the invention is thus (O, O2-0.48) + O, 28 0.3-ODb RUR / t, without taking into account the improvement in steel quality. Claims The method of steel production in an open-hearth furnace, including the pure boiling of metal, the treatment of slag with a deoxidizing mixture while simultaneously flushing the metal with a neutral or inert gas, introducing ferroalloys into the metal, adjusting the composition of the gas phase and pressure in the working space of the furnace, and the release of metal, characterized by , in order to reduce the consumption of neutral or inert gas and to maintain a higher temperature in the working space of the furnace, before the slag is treated with a deoxidizing mixture into the working space. the furnace space through the reclaimers introduces counter flows of fan air and at the same time begins the introduction of neutral or inert gas, continuously and evenly increasing its quantity into the blast and reducing the amount of ventilation air by the same amount and completely stopping it before introducing ferroalloys into the metal, and from the beginning of slag treatment with a deoxidizing mixture to introducing ferroalloys into the metal into the furnace working space, the amount of fuel is 1.051.1 times higher than stoichiometric ki necessary with respect to the content of free oxygen in the gas phase of the furnace. 79183108 Sources of information, M., Metalpurgizdat, 1961, p. 336-337 taken into account in the examination 1, E. V. Abrosimov, I. A. Ansheles, according to the application No. 2788227, cl. C 21 S S / O4, Kudrin V. A. and others. Metallurgists. 1979 (prototype). 2. USSR author's certificate