RU2359044C1 - Method of iron metl receiving, particularly steel melt - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to without-coke iron manufacturing from lump iron-bearing materials or pellets. On layer of carbon-bearing material it is fed iron-bearing and carbon-bearing material through the slot-like cavity in coat of furnace in the form of free-falling nappe, directed into near-wall region of furnace, with formation of mixture in furnace on-the-mitre of friction slope by means of its feeding. Simultaneously it is loaded reducing reactor by iron-bearing material, and higher its level it is formed layer of carbon-bearing material for correction of gas composition, delivered from melting furnace. Material is blown through in melting furnace by oxygen-containing and heated in indirect action plasmatron by oxygen-containing and natural gas. Received in melting furnace reducing gas is fed into top part of reducing reactor, it is defined composition and temperature of gas in top part of reducing reactor is compared with established and at changing of reducers concentration or temperature more than for 10%, they are corrected by gas from plasmochemical gas generator, there are repeated material feed cycles into melting furnace depending on mass of received metal.

EFFECT: purposeful usage of high reduction potential of effluent gas for providing of stage of solid-phase reduction and application of unit with less dimensions and expenditures.

4 cl, 5 tbl, 1 ex

Description

The invention relates to coke-free production of iron and the creation of a method for producing a molten iron, in particular steel, from lumpy iron-containing materials or pellets.

A known method for producing cast iron from iron-containing oxide material, including preliminary reduction to produce sponge iron in a shaft furnace and subsequent melting in a melting gasifier with simultaneous production of reducing gas by supplying solid carbon-containing material and oxygen or oxygen-containing gas, feeding the reducing gas obtained in the melting gasifier into shaft furnace, removal of blast furnace gas from it, purification from СО ₂ and Н ₂ О, heating and its return to the shaft furnace l (Japanese Application No. 63-47308, declared. 18.08.86, No. 61-192462, publ. 02.29.88).

The implementation of the known method is associated with difficulties arising from the heating of blast furnace gas to a reduction temperature before being fed into the shaft furnace. The reduction of iron-containing material occurs in the temperature range from 750 to 850 ° C, and it is very difficult to develop such temperatures in the heat exchanger in one heating step, and therefore, to achieve the required temperature, it is necessary to complicate the process with additional heating measures.

The closest in technical essence and the achieved result (prototype) method is adopted for producing molten iron or liquid steel intermediates from fine-grained iron-containing material, including its supply and melting in the melting gasification zone, in which, when the carbon-containing material and oxygen-containing gas are supplied, reducing gas is simultaneously obtained in the layer of solid carbon carriers, according to the invention, a fine-grained iron-containing material is fed into the melting gasifier using a ki a sulfur burner with the formation of a high-temperature combustion zone, centrally above the layer of solid carbon carriers, while a lump of carbon-containing material and lump of iron-containing material are additionally introduced into the melting gasification zone through the supply pipelines entering the upper zone of the melting gasifier, and with the help of a reducing gas formed in zone melting gasification, carry out a preliminary reduction of iron ore, and the reducing gas leaving the smelter gasifier fail to restore untreated from dust (Patent of Ukraine No. 37264, decl. 07/18/1996, publ. 15.15.2001, bull. No. 4, 2001).

However, this method does not ensure the quality of the reduced metal due to the obligatory presence of oxides in the reducing gas, which are associated with the technology of burning gases.

The basis of the invention is the task of creating a method for producing an iron melt, in particular steel, by using the technological capabilities of plasma technologies for high-temperature heating of iron ore material and the formation of reducing gas in relation to the processes of direct production of iron melt, the use of coal as an energy carrier and reducing agent to compensate for heat balance and correction the composition of the gas in the process of reductive melting and pre-reduction, and thereby to imitate the operation of two units used in metal smelting, reduce the temperature of the input of the reducing gas leaving the smelting furnace to a value acceptable for preliminary reduction of the iron-containing material by blowing the material from top to bottom through a layer of coal and, as a result, reduce the cost of the direct metal production process and, at the same time, , conduct the recovery reaction stably and efficiently.

The problem is solved in that in a method for producing an iron melt, in particular a steel melt, comprising loading into a melting gasification zone a lump of carbon-containing material and lump of iron-containing material through separate feeders included in the upper zone of the melting furnace, melting and reducing the material in the melting furnace, recovery iron-containing material in a reduction reactor using a reducing gas formed in the melting gasification zone according to the invention carbon holding and iron-containing materials are fed into the furnace with a predetermined mass ratio, and initially a layer of carbon-containing material is created on the hearth of the furnace, onto which iron-containing and carbon-containing material is fed, the resulting mixture is formed in the furnace at an angle equal to the angle of repose, by feeding it through a slit-like cavity into the lid of the furnace in the form of a freely falling jet, which is sent to the wall region of the furnace, in parallel, load the reactor with iron-containing material, the mass of which is determined based on the required final weighted average degree of metallization, while above the level of the iron-containing material, a predetermined layer of carbon-containing material is formed to correct the composition of the gas coming from the smelting furnace, the material is blown in the smelter with oxygen-containing and heated in indirect plasma torches with oxygen-containing and natural gas, and the recovery obtained in the smelting furnace is fed gas in the upper part of the reactor, determine the composition and temperature of the gas in the upper part of the reactor, compared with the set when the concentration of reducing agents or the temperature is changed by more than 10%, they are corrected with gas from plasma-chemical gas generators, the cycles of supplying materials to the smelting furnace are repeated depending on the mass of the metal obtained, and the gas leaving the reactor is fed to the afterburning of the iron-containing material in the reactor, while the mass the ratio of carbon-containing material to iron-containing material is in the range of 0.2-0.4, and lumpy iron-containing material in the reactor is formed at two temperatures polar zones divided grate, wherein the reactor and the melter is charged with preheated iron-containing material.

The predetermined mass ratio of the carbon-containing material (coal) to the iron-containing material (pellets) is taken in the range of 0.2-0.4 from the condition of ensuring an acceptable concentration of sulfur and carbon in the resulting metal.

The initial loading of the coal layer into the melting furnace reduces the sintering of the charge on the hearth of the furnace. A mixture of carbon-containing and iron-containing materials is fed to the coal layer in the smelting furnace into the wall region of the furnace and is formed at an angle of repose so that the channel of the gas leaving the furnace is on the side of the wall opposite to the charge. The inclined surface of the mixture (charge) is a gas-permeable surface through which gas flows. The presence of carbon-containing material (coal) in the furnace at such a high temperature can reduce energy consumption per ton of hot metal in comparison with known processes.

Continuous heating of the charge with a uniform temperature profile is achieved by symmetrical installation of plasmatrons relative to the longitudinal axis of the furnace at an angle to the bottom of the furnace and the supply of oxygen-containing gas above the assumed upper boundary of the melt.

In connection with the upper supply of reducing gas to the reducing reactor and the lower exhaust gas outlet, the iron-containing material is formed in two temperature zones. Initially, the material is loaded into a cavity formed by two grates separated by the height of the reactor, and then the remaining mass of material is loaded above the upper grate based on the required final weighted average degree of metallization. Above the level of the filled material, a coal layer is formed to correct the composition of the gas coming from the smelter. The heated lower layer of material located between the grates is sent to a melting furnace or for solid-phase reduction, and the upper metallized material is for subsequent use. The waste gas from the reduction reactor is fed to the afterburning in the reactor for heating the iron-containing material.

In the process of the present invention, the material is heated, melted and reduced using a plasma melting furnace, and solid phase reduction is carried out in a vertical reduction reactor. Both units have a common wall, and the inner surfaces of the covers serve as the channel wall for transferring the reducing gas from the smelter to the reactor. The device in which the present invention may be practiced is not limited. The invention can be implemented in various types of equipment with direct production of molten iron with bypass without significant heat loss of hot reducing gas from the smelter to the reactor, with an upper gas supply to the reactor and a lower exhaust gas outlet.

The method is as follows.

In the method, the raw lumpy iron-containing material is preheated. A layer of coal is placed under the melting furnace, then pellets and coal are fed into the furnace through separate feeders with a mass ratio of carbon-containing material to iron-containing material in the range of 0.2-0.4. The material is fed into the furnace through a slit-like cavity in the lid in the form of a freely falling jet, which is directed to the wall region of the furnace, and thus the resulting mixture is formed in the furnace at an angle equal to the angle of repose.

In parallel, the recovery reactor is loaded with heated pellets. In connection with the upper supply of reducing gas through the column of pellets and the lower exhaust gas outlet, the pellets are arranged in two temperature zones. First, the pellets are loaded into the lower part of the reactor into a cavity formed by two grates spaced apart along the height of the reactor. Then, pellets are loaded above the upper grate based on the desired final weighted average degree of metallization. Above the level of the pellet layer, a coal layer is formed to correct the composition of the gas coming from the smelter.

Indirectly mounted plasma torches are installed symmetrically at an angle to the hearth in the melting furnace. The plasmatrons are launched in the melting furnace and air-oxygen mixture is blown through the tuyeres installed above the assumed upper boundary of the melt.

Under the influence of high-temperature plasma jets, the iron-containing material melts, and the level of the material initially loaded in the furnace decreases. Maintain the charge level in the furnace constant by reloading the required mass of coal and pellets, depending on the mass of the metal obtained. Auxiliary additives such as lime, which acts as a sulfur and phosphorus removing agent, are added to the feed mixture. The material is purged with an oxygen-containing material and oxygen-containing and natural gas heated in indirect plasma torches of indirect action. The reducing gas obtained in the smelting furnace is fed to the top of the reduction reactor. Since at the initial stage the temperature and chemical composition of the gas does not correspond to the solid-phase reduction process, the gas composition is adjusted with the reducing gas obtained in plasma-chemical gas generators. The reducing gas passes through a layer of coal and a column of pellets and is discharged at the bottom of the reactor. It becomes possible to use reducing gas formed from coal. By increasing the total amount of reducing gas provides its high recovery potential. When the temperature and gas composition reach the set value, the plasma chemical gas generators are turned off, and when the concentration of the reducing agents or the temperature is changed by more than 10%, the gas composition is again adjusted by additional gas supply from the included plasma chemical gas generators. The composition of the gas is controlled by gas analyzers, and the temperature by thermocouples.

Thus, to ensure the stability of the process of metallization of the pellets, it is necessary to maintain a sufficient amount of reducing gas.

After the metallization of the pellets is completed, a layer of spent carbon-containing material is first removed, then a layer of pellets is released from the lower zone of the reduction reactor bounded by two grates, and then metallized pellets are released from the upper temperature zone, in which full specified metallization is guaranteed. A layer of pellets from the lower temperature zone is sent to a reduction reactor for additional metallization or to a plasma melting furnace. The waste gas from the reactor is sent to the pellet preheater in the reactor.

Concrete example

The production of steel and metallized pellets was carried out on the installation of direct production of steel, consisting of a 2.2 m ³ smelting furnace and 3.0 m ³ reducing reactor, having one common wall of refractory bricks and interconnected by a channel for passing gas from the smelting furnace into a reduction reactor. In the lower lateral parts of the melting furnace, two indirect-acting plasma torches with a power of 0.5 MW each are installed, directed at an angle to the furnace bottom. The reduction reactor is equipped with two plasma-chemical gas generators, the reducing gases from which are sent to its upper part.

As starting materials for the production of steel and metallized pellets, pellets of TsGOK and coal (anthracite) of the Donetsk basin were used.

Table 1 The chemical composition of the pellets Fe _GENERAL ,% Re ₃ About ₃ ,% FeO,% SiO ₂ ,% CaO,% MgO,% 63,4 87.2 3,1 5.1 3.16 0.88

To obtain 2 tons of steel, a mixture of the following composition was used:

Table 2 Name Amount, Pellets 3 Anthracite 1.3 Lime 0.2 Fluorspar 0,0

Initially, 440 kg of anthracite is charged under the smelting furnace, then pellets preheated to 400-600 ° C and anthracite are fed into the furnace together through separate feeders with a mass ratio of anthracite to pellets of 0.25.

The materials are fed into the furnace through a slit-like cavity in the lid and form a mixture of pellets and coal in the furnace at an angle equal to the angle of repose. The initial mass of loading of pellets and coal onto a coal bed is 1.9 tons (1.37 tons of pellets and 0.53 tons of coal).

Simultaneously with the melting furnace, the reduction reactor is loaded with preheated pellets. First, 1.4 tons of the original pellets are loaded into the lower part of the reactor, then the grate is installed and the next portion of pellets weighing 4.4 tons is loaded. 700 kg of coal are poured on top of the pellets.

After loading the melting furnace and the reduction reactor, the plasmatrons of the melting furnace are turned on and air, natural gas, and oxygen are supplied. Set the total costs for 4 plasmatrons and 4 nozzles:

natural gas - 28 g / s;

air - 320 g / s;

oxygen - 85 g / s.

Under the influence of plasma jets and injected oxygen, coal is burned and pellets are melted, as a result of which the level of the initially loaded material decreases. 5-10 minutes after the start of melting, additional loading of the remaining pellets and coal begins. Lime and fluorspar are introduced together with pellets. The reducing gas obtained in the smelting furnace is fed to the top of the reducing reactor. In the course of melting, the temperature of the exhaust gas increases from 200 ° C to 1100 ° C, while the chemical composition of the gas also changes. Since at the initial stage the temperature and chemical composition of the gas does not correspond to the conditions of intensive solid-state reduction processes, the composition and temperature of the gas leaving the smelting furnace are adjusted with the reducing gas obtained in plasma-chemical gas generators. After the start of the melting, an additional 2 plasmatrons in plasma-chemical gas generators with a total flow rate are included to correct the temperature and chemical composition of the reducing gas:

natural gas - 7 g / s;

air - 115 g / s;

oxygen - 8 g / s.

As a result of the operation of the correcting plasmatrons, the gas temperature in the upper part of the reduction reactor was at a level of 1030-1050 ° C. The gas in the upper part of the reduction reactor had the following chemical composition:

Table 3 H ₂ % N ₂ ,% WITH,% CO ₂ % 24 26 47 3

The content of reducing agents (H ₂ + CO) in the reducing gas was 65 ± 5%.

The temperature of the reducing gas is controlled either by turning off the plasmatrons of the plasma-chemical gas generators or by reducing their power, and the composition of the reducing gas is adjusted by changing the supply of natural gas through the plasma torches.

The melting time in the melting furnace is 1 hour. After the end of the smelting, the opening is opened and the metal and slag are released. After that, the melting cycle in the melting furnace is repeated. Metallized pellets from the reduction reactor are discharged at intervals through two melts. The degree of metallization (Fe _MET / Fe _GEN ) pellets after two hours of heat recovery is 82-84%. The composition of the steel obtained in the melting furnace is shown below.

Table 4 The chemical composition of steel FROM, % Si,% Mn,% S,% P% Fe,% 0.06-0.08 0.0025-0.005 0.01-0.05 0.008-0.02 0.008-0.02 99.7-99.9

Table 5 The chemical composition of metallized pellets Fe _MET % FeO,% Re ₂ About ₃ ,% Fe _GENERAL ,% The degree of metallization,% 62.7 20,0 - 75.8 82.7 65,2 13,2 2.7 77.3 84.3

EFFECT: invention makes it possible to purposefully use the high recovery potential of the exhaust gas, makes it possible to provide the recovery stage with a sufficient amount of reducing gas, and therefore, use installations with smaller sizes and lower costs.

Claims (4)

1. A method of producing a molten iron, in particular a molten steel, comprising loading into a melting gasification zone a lump of carbon-containing material and a lump of iron-containing material through separate feeders included in the upper zone of the melting furnace, melting and reducing the material in the melting furnace, reducing the iron-containing material in a reduction reactor using a reducing gas formed in the melting gasification zone, characterized in that the carbon-containing and iron-containing materials served in a furnace with a given mass ratio, and initially on the hearth of the furnace create a layer of carbon-containing material, which serves iron and carbon-containing material through a slit-like cavity in the lid of the furnace in the form of a freely falling jet directed into the wall region of the furnace, with the formation of the mixture in the furnace at an angle equal to the angle of repose, the recovery reactor is loaded in parallel with iron-containing material, the mass of which is determined based on the required final weighted average degree m metalization, while above the level of the iron-containing material, a predetermined layer of carbon-containing material is formed to correct the composition of the gas coming from the smelting furnace, the material in the smelting furnace is blown with oxygen-containing and heated in indirect plasma torches with oxygen-containing and natural gas, and the reducing gas obtained in the smelting furnace is fed to the upper part reduction reactor, determine the composition and temperature of the gas in the upper part of the recovery reactor, compare with the specified and at enenii reducing the concentration or temperature of more than 10% of gas is corrected from the gasifiers plazmohimicheskih, repeated cycles of feeding materials into the melting furnace according to the weight of the produced metal, and the effluent gas from the reduction reactor is fed to the afterburning in the preheating reactor ferrous material. 2. The method according to claim 1, characterized in that the mass ratio of the carbon-containing material to the iron-containing material is in the range of 0.2-0.4. 3. The method according to claim 1, characterized in that the lumpy iron-containing material in the reduction reactor is formed in two temperature zones separated by grates. 4. The method according to claim 1, characterized in that the preheated iron-containing material is loaded into the reduction reactor and the smelting furnace.