JP5942425B2 - Method for producing high-carbon molten iron using iron scrap - Google Patents

Description

  The present invention relates to a method for producing high carbon molten iron using an upper bottom blown converter type refining furnace or arc furnace using iron scrap and hot metal as main raw materials, and more specifically, heating and carburizing of iron scrap. The present invention relates to a method for producing high-carbon molten iron capable of reducing the amount of greenhouse gas generated from carbonaceous materials used for the purpose.

In recent years, reduction of CO ₂ gas emissions has become an important issue for the purpose of protecting the global environment and preventing global warming. In particular, in steelworks, reducing CO ₂ gas emissions is the most important issue related to the survival of companies. On the other hand, from the viewpoints of resource saving and environmental problems, in recent years, it has become a technical problem to manufacture steel products by recycling and recycling iron scraps that are generated in large quantities at steelworks. This is because hot metal production in a blast furnace requires a great deal of energy to reduce and melt iron ore, whereas iron scrap requires only heat of melting. This is because the amount of energy used for reducing heat of the stone can be reduced, and there is an advantage that energy saving and CO ₂ gas reduction can be realized.

  By the way, conventionally, an arc furnace has been generally used as a refining apparatus for producing molten iron using iron scrap. However, in the case of a conventional arc furnace, a large amount of electric power is consumed for melting iron scrap. Therefore, when the electric power price is high as in Japan, the manufacturing cost becomes high. Therefore, as a method for economically melting iron scrap without using an arc furnace, a converter-type smelting furnace with a high oxygen gas supply capacity is used, an inexpensive carbon material is burned with oxygen gas, and the combustion heat of the carbon material is There has been proposed a method for producing molten iron by melting iron scrap using as a heat source.

  For example, in Patent Document 1, in an oxygen top bottom blowing converter equipped with an oxygen top blowing device and a carbon material introduction nozzle installed at the furnace bottom, the carbon material blown from the carbon material introduction nozzle is burned to produce iron scrap, etc. In the method of producing molten steel by melting the solid iron raw material, 10-30% more molten steel (referred to as “additional molten steel”) is produced in the converter than the desired amount of produced steel, and the desired amount of produced steel After the steel is produced, a method for producing the molten steel by using the additional molten steel together with the solid iron raw material at the next charge is proposed.

However, carbon materials derived from fossil fuels such as coke and graphite used as fuel in Patent Document 1 increase the amount of CO ₂ gas in the atmosphere when burned. From the viewpoint of preventing global warming, the amount of fossil fuel-derived carbon should be reduced as much as possible.

  In Patent Document 2, iron-containing cold material, carbonaceous material, oxygen, and ironmaking material are supplied to a melting-only converter in which seed hot water and molten slag exist, and the iron-containing cold material is carburized and melted to obtain high carbon. When obtaining molten iron, at the time of discharging from the melting converter, a part of the high-carbon molten iron is left in the furnace and used as seed water for the next carburizing and melting operation of iron-containing cold material. A technique has been proposed in which all or part of the molten slag in the furnace is left in the furnace and used as a cover slag to prevent the scattering of iron dust during the next carburizing / melting operation of iron-containing cold material.

However, carbon materials such as coke and coal used as a carburized material and fuel in the converter exclusively for melting in Patent Document 2 have a high sulfur content, and the sulfur concentration of the high-carbon molten iron produced is high and discharged. Desulfurization treatment is required for the later high carbon molten iron. Similarly to Patent Document 1, carbon materials derived from fossil fuels such as coke and graphite used as fuel in Patent Document 2 increase the amount of CO ₂ gas in the atmosphere when burned. Therefore, the amount used should be reduced as much as possible.

  On the other hand, in Patent Document 3, in order to improve the electric power consumption in a conventional arc furnace, iron scrap and hot metal are used as an iron source and charged into the arc furnace, and carbon materials and oxygen gas are supplied to the arc furnace. In addition, there has been proposed a method for producing hot metal having a carbon concentration of 4.0% by mass or more using the heat of combustion of carbonaceous material by oxygen gas.

However, since carbon materials derived from fossil fuels such as coke, coal, and graphite used as fuel in Patent Document 3 increase the amount of CO ₂ gas in the atmosphere when burned, as in Patent Documents 1 and ₂ , From the viewpoint of preventing global warming, the amount of fossil fuel-derived carbon should be reduced as much as possible.

JP-A-56-58916 Japanese Patent Laid-Open No. 1-8214 JP 2011-111625 A

  The present invention has been made in view of the above circumstances, and the purpose of the present invention is to produce carbon-derived carbonaceous material, which is carbon neutral, using fossil such as coke and coal. It is intended to provide a method for producing high-carbon molten iron using iron scrap that can be effectively used as a heat source and a carburizing material that replaces a fuel-derived carbon material, and thereby reduce the amount of greenhouse gas generation.

The gist of the present invention for solving the above problems is as follows.
[1] Charcoal material in which iron scrap and hot metal are charged into a smelting furnace as an iron source, oxygen gas is supplied into the smelting furnace, and the iron scrap in the smelting furnace is supplied into the smelting furnace. While melting by the combustion heat by the oxygen gas and the sensible heat of the hot metal, the iron scrap is carburized by the carbon material and the hot metal, and high carbon molten iron having a carbon concentration of 3.0% by mass or more is contained in the smelting furnace. A method for producing high-carbon molten iron using iron scrap, characterized in that a biomass-derived carbon material is used as part or all of the carbon material.
[2] Production of high carbon molten iron using iron scrap according to [1], wherein the smelting furnace is an upper bottom blowing converter type smelting furnace for supplying the oxygen gas by blowing up Method.
[3] The smelting furnace is an arc furnace, and the iron scrap is melted by the heat of the arc generated in addition to the combustion heat of the carbonaceous material and the sensible heat of the hot metal. 1] The manufacturing method of the high carbon molten iron using the iron scrap as described in 1].
[4] The high concentration using the iron scrap according to any one of [1] to [3] above, wherein a sulfur concentration of the biomass-derived carbon material is 0.10% by mass or less. A method for producing molten carbon.
[5] X (kg-carbon material / t-molten iron) is the total amount of the biomass-derived carbon material, the sulfur concentration of the carbon material is a (mass%), the hot metal before refining, and the sulfur concentration of iron scrap. When the weighted average value is b (mass%) and the allowable maximum sulfur concentration of the high-carbon molten iron at the end of refining is c (mass%), the total amount X of the carbonaceous material can be obtained by the following equation (1). The iron scrap according to any one of [1] to [4] above, wherein the iron scrap is determined based on a total amount X of the carbon material and the amount of the iron scrap is determined. The manufacturing method of the high carbon molten iron used.
X = [(c−b) / a] × 1000 (1)
[6] The charcoal material derived from biomass is any one or more of biomass charcoal derived from palm coconut shell, biomass charcoal derived from palm palm empty fruit bunch, and biomass charcoal derived from palm palm trunk, A method for producing high-carbon molten iron using the iron scrap according to any one of [1] to [5] above.
[7] During supply of oxygen gas into the smelting furnace, any one of iron sources comprising iron ore, iron ore sintered ore, mill scale, iron making dust, magnetic separation scrap, and steel cutting scrap Alternatively, the method for producing high-carbon molten iron using iron scrap according to any one of [1] to [6] above, wherein two or more types of iron sources are put into the smelting furnace.

  According to the present invention, when producing high-carbon molten iron using iron scrap and hot metal as the main raw material, the carbon-derived carbonaceous material that is carbon neutral is used as the heat source and the carburizing material. According to the usage ratio of the material, it is possible to reduce the amount of greenhouse gas generated by the combustion of the heat source. Moreover, when a biomass-derived carbon material having a sulfur concentration of 0.10% by mass or less is used, mixing of sulfur from the carbon material into the high carbon molten iron is suppressed, and the produced high carbon molten iron is subjected to desulfurization treatment. Without being able to operate in the next process, it becomes possible to use a large amount of biomass-derived charcoal by eliminating the shortage of heat source due to sulfur contamination, increasing the proportion of iron scrap, and high carbon It becomes possible to increase the production amount of molten iron.

It is a schematic diagram of the longitudinal section of the top bottom blowing converter type refining furnace equipment to which the present invention is applied. It is a schematic diagram of the longitudinal section of the arc furnace to which the present invention is applied.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  First, a first embodiment in which the present invention is applied to an upper bottom blowing converter type refining furnace facility will be described. FIG. 1 is a schematic view of a vertical section of an upper bottom blown converter type refining furnace equipment to which the present invention is applied.

  The converter-type refining furnace equipment 1 has iron scrap 14 and hot metal 12 charged therein, a refining furnace main body 2 for producing high carbon molten iron from the charged iron scrap 14 and hot metal 12, and a refining furnace main body 2. The exhaust gas generated from the refining furnace main body 2 through the upper blown oxygen lance 4 that can move up and down to the internal space of the refining furnace main body 2 through the upper furnace port 3 and the duct 8 that covers the furnace port 3 (main In addition, a gas recovery device (not shown) for recovering CO gas), a hopper 9, 9a, a cutting device 10, 10a, and a chute 11 constituting a part of the raw material charging device. The refining furnace main body 2 is provided with a bottom blowing tuyere 5 penetrating the furnace bottom and a hot water outlet 7 penetrating the side wall. The bottom blowing tuyere 5 communicates with a gas introduction pipe 6, and stirring gas such as Ar gas or nitrogen gas or refining oxygen gas supplied from the bottom blowing tuyere 5 through the gas introduction pipe 6. However, the chute 11 passes through the duct 8 and reaches directly above the furnace port 3, and the raw material is charged into the furnace from the furnace port 3 through the chute 11. It is configured as follows.

  Using the top bottom blown converter type refining furnace equipment 1 configured as described above, the present invention is carried out as follows.

  First, iron scrap 14 and molten iron 12 are charged into the refining furnace body 2 as main raw materials. In the present invention, the iron scrap 14 is basically the reaction heat between the carbon material 15 supplied to the refining furnace body 2 and the oxygen gas supplied from the top blowing lance 4 to the refining furnace body 2, that is, the carbon material 15. Since it is melted by the combustion heat, the mixing ratio of iron scrap 14 (the mixing ratio of iron scrap = iron scrap charging amount x 100 / (molten metal charging amount + iron scrap charging amount)) is the amount of sulfur from the carbonaceous material 15 When mixing is not taken into consideration, it is not necessary to specify in particular, and it may be set according to the amount of carbon material 15 used. In other words, what is necessary is just to set the usage-amount of the carbonaceous material 15 according to the arbitrary mixture ratios of the iron scrap 14. FIG. However, if the mixing ratio of the iron scrap 14 is increased too much, the melting time becomes longer. Therefore, the mixing ratio of the iron scrap 14 may be about 50% by mass at the maximum value. The hot metal 12 to be used is preliminarily subjected to desulfurization, desiliconization, and dephosphorization pretreatment as necessary.

  The iron scrap 14 is charged into the furnace along the blending ratio set based on the amount of the carbonaceous material 15 that is the heat source, and then the hot metal 12 is loaded into the furnace along the blending ratio. After that, a predetermined amount of the biomass-derived carbon material 15 stored in the hopper 9 is cut out by the cutting device 10 and charged into the furnace from the furnace port 3 through the chute 11 as a heat source. In this case, a part of the carbon material 15 may be charged in the furnace together with the iron scrap 14 in advance. Furthermore, in order to form molten slag 13 for refining in the furnace, a fossil material such as quick lime, fluorite, and dolomite is charged into the refining furnace main body 2 through a raw material charging device (not shown). To do. Furthermore, in the heat calculation comparing the calorific value calculated from the addition amount of the carbonaceous material 15 with the addition amount of the slagging agent and the target temperature value of the high carbon molten iron at the time of tapping, there is a thermal margin. The iron source 16 in an amount corresponding to this heat margin is cut out from the hopper 9a by the cutting device 10a and charged into the furnace via the chute 11. The iron source 16 supplied from the hopper 9a functions as a coolant.

As the iron source 16, any one or more of iron ore, iron ore sintered ore, mill scale, iron making dust, magnetic separation scrap, and steel cutting scrap generated in a machine factory is appropriately selected. And use it. Even when the iron source 16 contains FeO or Fe ₂ O ₃ , these are reduced to iron by the carbon contained in the hot metal 12 and the carbon material 15 in the furnace, so that the resources are effectively used. Moreover, magnetic separation waste collect | recovers the metal components mixed in converter slag etc. from the crushed slag by magnetic separation.

Then, while blowing bottom blowing gas from the bottom blowing tuyere 5, oxygen gas is supplied from the top blowing oxygen lance 4 into the furnace to start refining. In this case, when the oxygen gas supplied from the top blown oxygen lance 4 directly collides with the molten iron 12, a decarburization reaction of the molten iron 12 (2C + O ₂ = 2CO) occurs, and the carbon concentration of the produced high carbon molten iron decreases. The flow rate and pressure of the oxygen gas blown from the top blown oxygen lance 4 are set so that the oxygen gas to be supplied is not consumed as much as possible in the decarburization reaction of the hot metal 12 but is mainly consumed in the combustion of the carbonaceous material 15.

The carbonaceous material 15 is combusted by oxygen gas along the reaction formula “2C + O ₂ = 2CO”, and the combustion heat is transmitted to the hot metal 12 through the molten slag 13, and the iron scrap 14 buried in the hot metal 12 is melted. . However, since the heat generated by the decarburization reaction of the hot metal 12 also contributes to the dissolution of the iron scrap 14, it is not necessary to completely prevent the decarburization reaction of the hot metal 12. A part of the carbon material 15 is dissolved in the hot metal 12, and the carbon concentration of the hot metal 12 diluted with the dissolution of the iron scrap 14 is increased. That is, the carbon material 15 has a function of carburizing the molten iron and the molten iron 12 generated by melting the iron scrap 14. By suppressing the decarburization reaction of the hot metal 12 as much as possible, the carbon material 15 functions as a carburizing material, so that the carbon concentration of the manufactured high carbon molten iron is ensured to be 3.0% by mass or more. During the refining, the carbon material 15 and the iron source 16 in an amount corresponding to the added amount of the carbon material 15 are appropriately charged into the furnace through the chute 11 from the furnace port 3.

  If a predetermined amount of the carbonaceous material 15 and oxygen gas are supplied, and the iron scrap 14 is melted to produce a high carbon molten iron having a predetermined temperature and a carbon concentration of 3.0% by mass or more, it can be illustrated as necessary. Fe-Mn alloy, Si-Mn alloy, etc. are poured into high carbon molten iron from a raw material charging device, and then the smelting furnace body 2 is tilted by a tilting device (not shown), and a ladle (not shown) is drawn from the tap 7. 1), the high carbon molten iron is discharged, and the production of the high carbon molten iron using the iron scrap 14 is completed. The manufactured high carbon molten iron is subjected to desulfurization treatment as necessary, and then subjected to decarburization refining in a converter.

  By the way, the biomass-derived carbon material 15 also contains sulfur as an impurity, like the fossil fuel-derived carbon material. In the above description, the addition amount of the biomass-derived carbon material 15 is not prescribed, and if the addition amount of the biomass-derived carbon material 15 increases, the sulfur concentration of the manufactured high carbon molten iron may exceed the target value. There is. In order to prevent the contamination of sulfur by the biomass-derived carbon material 15 to the high carbon molten iron to be produced, it is preferable to employ the following method.

That is, the total amount added per one charge of biomass-derived carbon material 15 is X (kg-carbon material / t-molten iron), the sulfur concentration of this carbon material 15 is a (mass%), hot metal 12 and iron before refining. When the weighted average value of the sulfur concentration of the scrap 14 is b (mass%) and the allowable maximum sulfur concentration of the high carbon molten iron at the end of refining is c (mass%), the maximum value of the total addition amount X of the carbonaceous material 15 is It is calculated by the following equation (1).
X = [(c−b) / a] × 1000 (1)
If only the biomass-derived carbon material 15 is added as a heat source and a carburized material, the amount of biomass-derived carbon material 15 added is equal to or less than the total addition amount X calculated by equation (1) The increase in the sulfur concentration due to the addition of the carbon material 15 can be suppressed to the allowable maximum sulfur concentration c or less of the high carbon molten iron. When a conventional fossil fuel-derived carbon material such as coke is used in combination, the maximum addition amount of the biomass-derived carbon material 15 is set in consideration of an increase in sulfur concentration due to sulfur contained in the fossil fuel-derived carbon material. It is necessary to decide. That is, it is necessary that the total amount of the sulfur content introduced by the fossil fuel-derived carbon material and the sulfur content introduced by the biomass-derived carbon material 15 does not exceed the allowable maximum sulfur concentration c of the high carbon molten iron. .

  Moreover, when only the biomass-derived carbon material 15 is added as a heat source and a carburized material, the amount of the biomass-derived carbon material 15 is set to the total addition amount X calculated by the equation (1). If the blending ratio is obtained, the obtained blending ratio of the iron scrap 14 is the maximum value within a range in which the manufactured high carbon molten iron does not need to be desulfurized.

  However, when the addition amount of the carbonaceous material 15 derived from biomass is set to the maximum value and the blending ratio of the iron scrap 14 is also set to the maximum value, the sulfur concentration of the high carbon molten iron at the end of the refining becomes the allowable upper limit value. Therefore, the addition of more carbon material means that the sulfur concentration of the high carbon molten iron is equal to or higher than the allowable maximum sulfur concentration c even in the case of the biomass-derived carbon material 15. In addition, it is not preferable to input the carbonaceous material during the refining, and it is not preferable to input the carbonaceous material even when the temperature measurement result of the high carbon molten iron at the end of the refining is lower than the target value. As a heat source not accompanied by an increase in the sulfur concentration, an Fe—Si alloy, metal Al, or the like can be used.

  The carbon material 15 to be used is carbon neutral as long as it is derived from biomass, and no greenhouse gas is generated. Therefore, it is not particularly necessary to specify from the viewpoint of generating a greenhouse gas. However, the biomass-derived carbon material 15 also contains sulfur as described above, and the addition of a large amount causes a problem that the sulfur concentration of the high carbon molten iron increases. As a result of various studies, if the sulfur concentration of the carbon material 15 is 0.10% by mass or less, the increase in the sulfur concentration in the high carbon molten iron due to the addition of the carbon material is small, and it is understood that a large amount of the carbon material 15 can be used as a heat source. It was. That is, it is preferable that the biomass-derived carbon material 15 to be used is a carbon material having a sulfur concentration of 0.10% by mass or less.

  From this viewpoint, the biomass-derived carbon material 15 includes biomass coal derived from palm coconut shell (sulfur concentration ≈ 0.05 mass%), biomass coal derived from palm palm empty fruit bunches (sulfur concentration ≈ 0.07 mass%), palm palm It is preferable to use any one or more of trunk-derived biomass charcoal (sulfur concentration≈0.10 mass%).

  For example, the difference between the weighted average value b of the sulfur concentration of the hot metal 12 and iron scrap 14 before refining and the allowable maximum sulfur concentration c of high carbon molten iron at the end of refining, that is, the amount of sulfur mixed from the carbonaceous material during refining When the upper limit of the allowable increase in concentration is 0.001% by mass, when using general coke with a sulfur concentration of 0.5% by mass as the carbon material, the carbon material Only 2kg-carbon / t-molten coke is added as a unit, but when using biomass charcoal with a sulfur concentration of 0.10 mass%, the sulfur concentration is 1/5 compared to coke. Therefore, it is possible to add 10 kg-charcoal material / t-molten biomass charcoal, which is 5 times the amount of addition, and mix many iron scraps 14 and iron sources 16 as the heat source to be added increases. It becomes possible. The allowable maximum sulfur concentration c of high carbon molten iron is determined by the sulfur concentration standard of a steel type produced by decarburizing and refining this high carbon molten iron in a converter.

  Next, a second embodiment in which the present invention is applied to an arc furnace will be described. FIG. 2 is a schematic diagram of a longitudinal section of an arc furnace to which the present invention is applied.

  In FIG. 2, reference numeral 21 is a DC arc furnace, 22 is a melting chamber, 23 is a furnace lid, 24 is an upper electrode, 25 is a furnace bottom electrode, 26 is a hot metal charging rod, 27 is a charging pan for containing hot metal, 28 is a crane, 29 is a tap, 30 is an oxygen gas supply lance, 31 is a carbonaceous material supply lance, 32 is a raw material charging chute, and 33 is an arc. In addition, the code | symbol 12 is hot metal, 14 is an iron scrap, 15 is a carbonaceous material, 16 is an iron source, These are the same as FIG. 1 of the 1st form example.

  The furnace lid 23 is removed, and the iron scrap 14 is charged into the melting chamber 22. After the iron scrap 14 is charged, the iron scrap 14 is inserted through a hot metal charging rod 26 that penetrates the side wall of the DC arc furnace 21. The molten iron 12 is charged into the melting chamber 22 from the charging pot 27 lifted by the crane 28. In this case, since the iron scrap 14 is melted by the heat of the arc 33, the sensible heat of the hot metal 12, and the combustion heat of the carbonaceous material 15, the mixing ratio of the iron scrap 14 is the converter type refining furnace of the first embodiment. Unlike the case where the facility 1 is used, an arbitrary value can be set regardless of the supply amount of the carbonaceous material 15.

  When a predetermined amount of hot metal 12 is charged, the supply of hot metal 12 from the charging pan 27 is finished, a direct current is supplied between the upper electrode 24 and the furnace bottom electrode 25, and the upper electrode 24 and the furnace bottom electrode are supplied. An arc 33 is generated between the iron scrap 14 and the upper electrode 24. Then, the iron scrap 14 is melted by the generated arc heat and the sensible heat of the hot metal 12 to generate molten iron (not shown). The molten iron produced is mixed with the hot metal 12 and the carbon concentration of the hot metal 12 is diluted.

  When the oxygen gas supply lance 30 and the carbonaceous material supply lance 31 can be inserted into the melting chamber 22 after energization, oxygen gas is supplied from the oxygen gas supply lance 30, and from the carbonaceous material supply lance 31, it is derived from biomass. The carbon material 15 is sprayed toward the hot metal 12 or molten slag in the melting chamber. The sprayed carbon material 15 reacts with the sprayed oxygen gas to generate combustion heat, functions as an auxiliary heat source for melting the iron scrap 14, and reduces power consumption. Further, a part of the carbonaceous material 15 is melted into the molten iron to be produced and the molten iron 12 in the furnace, and the carbon concentration of the molten iron 12 diluted with the melting of the iron scrap 14 is increased, and the carbon concentration is 3.0 mass. % Of high-carbon molten iron is produced. In this case, a part of the carbonaceous material 15 may be charged into the melting chamber 22 in advance simultaneously with the charging of the iron scrap 14 into the furnace. In addition, since the carbonaceous material 15 plays the role as a carbonized material for raising the carbon concentration of the hot metal 12 whose carbon concentration is diluted by the molten iron to be generated, the amount of the carbonaceous material 15 is larger than the chemical equivalent of the supplied oxygen gas. Carbon material 15 is supplied.

  In addition, when the iron scrap 14 starts to melt, it is preferable to charge the iron source 16 into the melting chamber 22 through the raw material charging chute 32 in order to improve productivity. Further, when the iron scrap 14 starts to melt, it is preferable that a flux such as quick lime is charged into the melting chamber 22 to form molten slag on the hot metal 12 to prevent the hot metal 12 from being oxidized and to keep warm. .

  If high carbon molten iron having a predetermined amount, a predetermined temperature, and a carbon concentration of 3.0% by mass or more is produced in the melting chamber, the melting chamber 22 is tilted toward the outlet 29 by a tilting device (not shown). From the tap 29, the high carbon molten iron having a carbon concentration of 3.0% by mass or more is poured into a holding container (not shown) such as a ladle. After pouring hot water, iron scrap 14 and hot metal 12 are newly charged into the melting chamber 22, and melting of the next heat is started. The manufactured high carbon molten iron is subjected to desulfurization treatment as necessary, and then subjected to decarburization refining in a converter.

  In the above operation, the carbon material 15 and the iron source 16 to be used conform to the first embodiment. Moreover, when suppressing the raise of the sulfur concentration of the high carbon molten iron by the carbon | charcoal material 15 and controlling the sulfur concentration of the high carbon molten iron at the time of completion | finish of refining to below the permissible maximum sulfur concentration c, it demonstrates by the 1st form example. As described above, the total addition amount X of the biomass-derived carbon material 15 is set using the equation (1).

  The arc furnace shown in FIG. 2 is a DC arc furnace, but the present invention can be applied without any problem even if an AC arc furnace is used. The carburizing method is carried out by top blowing projection from the lance, but it may be injection from above into the bath, or a dedicated nozzle is buried in the bottom of the furnace, and bottom blowing injection is also possible. I do not care.

  As described above, according to the present invention, when iron scrap 14 and hot metal 12 are used as main raw materials and a high carbon molten iron is produced using an upper bottom blown converter type refining furnace or an arc furnace, Moreover, since the carbon-derived carbonaceous material that is carbon neutral is used as the carburized material, it is possible to reduce the amount of greenhouse gas generated by combustion of the heat source according to the use ratio of the biomass-derived carbonaceous material. Moreover, when a biomass-derived carbon material having a sulfur concentration of 0.10% by mass or less is used, mixing of sulfur from the carbon material into the high-carbon molten iron can be suppressed, and desulfurization to the produced high-carbon molten iron is achieved. The treatment can be omitted and a large amount of biomass-derived charcoal can be used, the shortage of heat source due to sulfur contamination can be eliminated, the blending ratio of iron scrap 14 can be increased, and high carbon molten iron can be produced. The amount can be increased.

  An embodiment of the present invention in the converter type refining furnace facility shown in FIG. 1 will be described below.

  The top bottom blowing converter type refining furnace used had a furnace capacity of about 250 tons (hereinafter referred to as “ch”), and Ar gas was used as the bottom blowing gas for stirring. Table 1 shows examples of operating conditions and typical hot metal components in this example. The hot metal was desulfurized using a mechanical stirring desulfurization apparatus. As the iron scrap, iron scrap (slabs, steel plate crop scraps, etc.) generated at steelworks was used.

  In addition, in order to make it easy to understand the effect of the present invention, as shown in Table 1, the amount of hot metal used in the operating conditions is 170 tons, the temperature of the hot metal to be charged is 1330 ° C., and the high carbon molten iron at the time of tapping is used. The temperature was set to a constant condition of 1400 ° C., and the slagging material charging amount was also set to a constant condition.

  The used biomass charcoal is palm palm shell derived biomass charcoal having a sulfur content of 0.05% by mass (hereinafter referred to as “biomass charcoal A”), and palm palm empty fruit bunch having a sulfur content of 0.07% by mass. Three types of biomass charcoal derived from biomass (hereinafter referred to as “biomass charcoal B”) and biomass charcoal derived from palm palm having a sulfur content of 0.10% by mass (hereinafter referred to as “biomass charcoal C”) were used. . In some examples of the present invention, coke (sulfur content = 0.50 mass%) was also used.

  Difference between weighted average value b of sulfur concentration of hot metal and iron scrap and allowable maximum sulfur concentration c of high carbon molten iron at the end of refining, that is, the maximum amount of sulfur that can be tolerated even if it rises by charging carbon during refining The amount of carbon material added was determined based on the value. And the compounding quantity of the iron scrap was determined according to this carbon material addition amount. That is, the amount of iron scrap was set to the maximum value determined from the amount of carbonaceous material added. The same applies to Comparative Example 1.

  However, in Invention Example 1, the amount of carbon material added was matched to the amount used in Comparative Example 1 regardless of the upper limit value of the carbon material addition obtained from the sulfur concentration. Incidentally, in Comparative Example 1, coke (sulfur concentration = 0.50% by mass) is used as a carbonaceous material, and 500 kg / ch coke in which the amount of increase in sulfur concentration due to coke becomes an allowable maximum sulfur concentration c is added. This is an operation in which 20 tons of iron scrap is blended by adding 500 kg / ch coke (iron scrap blending ratio = 10.5% by mass). Table 2 shows the operation conditions and operation results of Examples 1 to 10 of the present invention and Comparative Example 1.

The amount of CO ₂ gas generated by the combustion of the carbonaceous material was calculated using the following chemical reaction formula (2).
C + O ₂ = CO ₂ (2)
According to the formula (2), 3.15 kg of CO ₂ gas was generated per 1 kg of coke (carbon content = 86 mass%), and about 1577 kg / ch of CO ₂ gas was generated in Comparative Example 1.

Inventive Example 1 was tested by replacing all the coke with biomass coal A. In Example 1 of the present invention, by replacing the entire amount of coke with biomass coal A, the amount of CO ₂ gas derived from fossil fuel by combustion of carbonaceous materials became zero, and the amount of greenhouse gas generated could be reduced. Invention Example 1 had the same amount of carbonaceous material as Comparative Example 1 and the same amount of iron scrap used. Moreover, the mixing of sulfur from the charcoal did not cause any problems.

In Examples 2-7 of the present invention, the sulfur content of the used biomass coal is lower than that of coke, so the amount of biomass coal added is increased to the upper limit of the allowable sulfur concentration, and the amount of iron scrap used is also the upper limit accordingly. Increased to. In Examples 2 to 10 of the present invention in which the amount of carbon material added was increased, oxygen gas of about 0.8 Nm ³ was increased per kg of the increased amount of carbon material.

  In the example 2 of the present invention, the biomass coal A is added at 5000 kg / ch to the upper limit of the allowable sulfur concentration increase of 0.001% by mass, and the amount of iron scrap used is increased by 12.5 t / ch compared with the comparative example 1. In Invention Example 3, 3571 kg / ch of biomass charcoal B is added, and the amount of iron scrap used can be increased by 8.9 t / ch compared to Comparative Example 1. In Invention Example 4, By adding 2500 kg / ch of biomass charcoal C, the amount of iron scrap used could be increased by 6.3 t / ch compared to Comparative Example 1.

  Moreover, in the example 5 of this invention with respect to the upper limit of the allowable sulfur concentration increase of 0.002 mass%, biomass coal A is added 10000 kg / ch, and compared with the comparative example 1, the amount of iron scrap used is 25.0 t / In Example 6 of the present invention, 7143 kg / ch of biomass coal B was added, and the amount of iron scrap used could be increased by 17.9 t / ch compared to Comparative Example 1, and Example 7 of the present invention Then, biomass coal C was added at 5000 kg / ch, and the amount of iron scrap used could be increased by 12.5 t / ch compared with Comparative Example 1.

In the present invention examples 2 to 7, by replacing the entire amount of coke with biomass charcoal, the amount of CO ₂ gas derived from fossil fuel by combustion of carbonaceous materials becomes zero, and the effect of preventing global warming is exhibited, and the amount of iron scrap used It was possible to increase production by increasing

  In Examples 8 to 10 of the present invention, a test was performed by replacing part of coke with biomass charcoal. The use ratio of coke and biomass charcoal can be varied according to sulfur concentration regulations, inventory, environmental measures, etc. of high carbon molten iron.

In the present invention example 8, coke 250 kg / ch, biomass coal A 2500 kg / ch addition, CO ₂ gas emission amount derived from fossil fuel by carbon material can be halved compared with Comparative Example 1, The amount of iron scrap used was increased by 6.9 t / ch. In Example 9 of the present invention, coke 250 kg / ch and biomass coal B 1786 kg / ch were added, and the amount of CO ₂ gas derived from fossil fuel derived from charcoal can be halved compared to Comparative Example 1, The amount of iron scrap used could be increased by 5.0 t / ch. In the present invention example 10, coke 250 kg / ch, biomass coal C 1250 kg / ch addition, CO ₂ gas emission amount derived from fossil fuel by carbon material can be halved compared with Comparative Example 1, The amount of iron scrap used could be increased by 3.8 t / ch.

  In the condition of Example 1 of the present invention in Example 1, the amount of increase in the amount of iron scrap used was changed from 12.5 t / ch to 10.5 t / ch while the addition amount of biomass coal A was 5000 kg / ch, and the surplus The iron source was thrown in from the furnace with respect to the heat source, and this invention example 11-15 was performed. Iron sources include converter dust collection dust (also called “OG dust”), iron ore, sintered ore of iron ore, mill scale, and steel cutting waste generated at machine shops. used.

  Table 3 shows the operation conditions and operation results of Examples 11 to 15 of the present invention. In addition, the iron yield improvement shown in Table 3 shows the amount of the coolant added from the furnace reduced to iron, compared to the case where no iron source is added.

  In Invention Example 15 to which steel cutting waste was added, the cutting waste did not need to be reduced, and high iron yield was improved, but Invention Examples 11 to 11 using an iron source mainly composed of iron oxide were obtained. 14 also improved the iron yield. In other words, it was confirmed that even an iron source mainly composed of iron oxide has an effect of improving the iron yield and increases the production amount. In other words, there was no problem even if the increase in the heat source was replaced not only with iron scrap but also with the iron source from the furnace, yielding was improved, and the production volume could be increased.

  In the present invention, the carbon-neutral biomass charcoal is replaced with a part or all of the conventional charcoal made of fossil fuel, so that the amount of greenhouse gas generated can be reduced. By using biomass charcoal with a sulfur content lower than that of the lumber, the shortage of heat source due to the sulfur concentration regulation of high-carbon molten iron is eliminated, and more iron scrap and iron sources from the furnace than before are used. Was able to increase production. In Comparative Example 1, which is the prior art, coke is used as the charcoal, but charcoal such as anthracite and graphite may be used, and the carbon such as anthracite and graphite is replaced with biomass charcoal. There is no problem.

DESCRIPTION OF SYMBOLS 1 Converter type refining furnace equipment 2 Refining furnace main body 3 Furnace opening 4 Top blowing oxygen lance 5 Bottom blowing tuyere 6 Gas introduction pipe 7 Outlet 8 Duct 9 Hopper 10 Cutting device 11 Chute 12 Hot metal 13 Molten slag 14 Iron scrap 15 Charcoal Material 16 Iron source 21 DC arc furnace 22 Melting chamber 23 Furnace lid 24 Upper electrode 25 Furnace bottom electrode 26 Hot metal charging rod 27 Charging pan 28 Crane 29 Hot water outlet 30 Oxygen gas supply lance 31 Carbon material supply lance 32 Raw material charging chute 33 arc

Claims (6)

Charging iron scrap and hot metal into the smelting furnace as an iron source, then supplying oxygen gas into the smelting furnace, and the oxygen gas of the carbonaceous material that supplied the iron scrap in the smelting furnace into the smelting furnace with dissolved by the combustion heat and sensible heat of the hot metal by the molten iron produced by dissolving iron scrap and carburization by the carbon of the carbon and in the hot metal of the carbonaceous material in the carbon concentration is 3.0 mass% A method for producing the above high carbon molten iron in the refining furnace,
With using the carbonaceous material of biomass as a total part of the carbonaceous material,
X (kg-charcoal material / t-molten iron) is the total amount of carbonaceous material derived from biomass, the sulfur concentration of the carbonaceous material is a (mass%), the weighted average value of the hot metal before refining and the sulfur concentration of iron scrap And b (mass%), and the allowable maximum sulfur concentration of the high carbon molten iron at the end of refining is c (mass%), the total addition amount X of the carbonaceous material is a value calculated by the following equation (1): It is the same or less, and the amount of iron scrap charged is determined based on the total amount X of the carbon material, and the sulfur concentration of the high carbon molten iron to be produced is controlled to the allowable maximum sulfur concentration c or less. A method for producing high-carbon molten iron using iron scrap.
X = [(c−b) / a] × 1000 (1)   2. The method for producing high-carbon molten iron using iron scrap according to claim 1, wherein the refining furnace is a top-bottom-blown converter type refining furnace that blows up the oxygen gas. 3.   The said smelting furnace is an arc furnace, The said iron scrap is melt | dissolved with the heat of the arc generated in addition to the combustion heat of the said carbonaceous material, and the sensible heat of the said hot metal, The said scraps are characterized by the above-mentioned. Of high-carbon molten iron using steel scrap.   The method for producing high-carbon molten iron using iron scrap according to any one of claims 1 to 3, wherein the biomass-derived carbonaceous material has a sulfur concentration of 0.10 mass% or less. . The biomass-derived charcoal material is any one or more of biomass charcoal derived from palm coconut shell, biomass charcoal derived from palm palm empty fruit bunches, and biomass charcoal derived from palm palm trunk, The manufacturing method of the high carbon molten iron using the iron scrap of any one of Claims 1 thru | or 4 . During the supply of oxygen gas into the smelting furnace, any one or two of iron sources comprising iron ore, iron ore sintered ore, mill scale, iron making dust, magnetic separation scrap, and steel cutting scrap The method for producing high-carbon molten iron using iron scrap according to any one of claims 1 to 5 , wherein the iron source is put into the smelting furnace.

Images