JP2002053909A - Steelmaking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steelmaking method by which, in a refining process, molten metal, such as molten iron and molten steel, is not contaminated and heat can efficiently be added. SOLUTION: In the refining process, plastic consisting essentially of carbon and hydrogen and the other material for adjusting the specific gravity are charged at the substantially same position in a reaction vessel or a molten metal carrying vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a steelmaking method for supplying a heat source in a refining process.

[0002]

2. Description of the Related Art In a steel refining process, not only is it necessary to apply enormous heat to keep iron or steel in a molten state, but also to improve the efficiency of the refining process and to produce high-quality steel. It is desirable to maintain a state where there is sufficient heat. For example, when a refining agent is blown into molten iron, the blown gas removes the sensible heat of the molten iron, so that the temperature of the molten iron cannot be reduced, and the processing time and the amount of the refining agent used are often limited. Also, even when controlling the tapping temperature from the converter, if the hot metal temperature is low or if the hot metal does not contain enough carbon, the temperature is raised by using more oxygen than usual to adjust the temperature. However, in that case, the amount of dissolved oxygen in the molten steel increases, and as a result, the quality of the steel decreases.

[0003] From such a viewpoint, a technique of passively shortening the treatment time to suppress heat radiation and a technique of positively injecting a carbon source such as coke powder into hot metal or molten steel to carburize the same. Is being developed.

[0004]

By the way, coal, coke, graphite and the like can be generally considered as a carbon source used in the steel making process, and these substances contain impurities such as sulfur, phosphorus and nitrogen. Therefore, the amount of use must be limited. In other words, when a large amount of these materials is used and a large amount of heat is added, it is necessary to provide a step of removing unavoidably mixed sulfur, phosphorus, and nitrogen, which leads to an increase in manufacturing cost.

[0005] Further, when the carbon source is put into molten iron or molten steel alone or added by injection, the yield of the carbon addition does not increase because the carbon source is scattered and the residue is left undissolved. In addition, if these carbon addition treatments are performed prior to the decarburization step, the carburization treatment will be performed under conditions close to the upper limit of carbon solubility in the molten iron, and the carburization yield will further decrease. I do.

The present invention has been made in view of such circumstances, and provides a steelmaking method capable of efficiently applying heat without contaminating molten metal such as hot metal or molten steel in a refining process. The purpose is to:

[0007]

In order to solve the above-mentioned problems, the present invention relates to a refining process, in which a plastic mainly composed of carbon and hydrogen and another substance for adjusting the specific gravity are fed into a reaction vessel or molten metal. Provided is a steelmaking method characterized by being charged into substantially the same position in a container.

In the present invention, a plastic mainly composed of carbon and hydrogen is used as a heat source instead of conventional coke or the like. Such a plastic has a small amount of impurity components such as sulfur and nitrogen as in a conventional carbon source. Since the material can be selected, the molten metal is not contaminated, and these removal steps can be omitted. In addition, plastics mainly composed of carbon and hydrogen generally have a low specific gravity, and it is difficult to reach a molten metal surface or a slag surface alone in a process that generates a large amount of gas. There is not much to function, and depending on the shape, more than half of the input amount is discharged out of the system by the exhaust gas flow, but as described above, the substance for adjusting the specific gravity is substantially made of a plastic mainly composed of carbon and hydrogen. In this case, the plastic mainly composed of carbon and hydrogen can effectively reach the molten metal surface or the slag surface without flowing into the upward flow blown up from the lower part of the container. Therefore, heat can be efficiently added.

In this case, as the substance for adjusting the specific gravity, one or both of a refining raw material and a substance containing a metal oxide can be used. Here, as the refining raw material, at least one of calcined lime, limestone, slaked lime, dolomite, and lightly calcined dolomite can be used. Examples of the substance containing the metal oxide include iron ore, mill scale, ironmaking dust, Mn ore, and C
At least one of r ore and Ni ore can be used.

[0010] When the plastic mainly composed of carbon and hydrogen and the substance for adjusting the specific gravity are charged, these compacts are manufactured, and the compact is charged into the reaction vessel or the molten metal transport vessel. Can be. Specifically, the plastic mainly composed of carbon and hydrogen and a substance for adjusting the specific gravity are mixed to partially or entirely melt or semi-melt the plastic, at least to the extent necessary to maintain the molded body. A briquette or extrusion molded product whose surface is bonded with the plastic can be put into the reaction vessel or the molten metal transport vessel. At this time, in order to ensure that the molded body reaches the molten metal surface or the slag surface without being flown into the upward flow blown up from the lower part of the container, the apparent density of the molded body should be 1100 kg / m ³ or more. It is preferable that the shape of the body is any one of a cylinder, a prism, a sphere, and a spheroid, and the mass of one molded body is 20 g or more. Further, the plastic mainly composed of carbon and hydrogen and the substance for adjusting the specific gravity may be injected into the reaction vessel or the molten metal transport vessel at substantially the same position by injection. further,
These can be introduced into substantially the same position through a blowing hole provided at the bottom of the reaction vessel or the molten metal transport vessel.

The plastics used in the present invention include polypropylene, polyethylene, polystyrene, polyvinyl acetylene, polycarbonate, polyethylene terephthalate, vinyl chloride, polyvinylidene chloride, polybutadiene, styrene-butadiene rubber (SBR), and ethylene-propylene elastic substance (EPM, EPDM), butyl rubber, ABS resin, polyvinyl alcohol, polyvinyl acetate, celluloid, plastics classified as engineering plastics such as nylon, etc., are not particularly limited as long as they are mainly composed of carbon and hydrogen. Or waste plastics, and if necessary, processed into powders can be used, but from the viewpoint of cost and effective use of industrial waste It is preferable to use La waste plastic.

Here, the waste plastics are plastics which are wastes as so-called garbage including debris and defective products generated at the time of manufacturing and processing in factories and the like. Paper and other inorganic and organic substances). Specific examples of such waste plastics include plastic bottles, plastic bags, plastic wraps, plastic films, plastic trays, plastic cups, magnetic cards, magnetic tapes, IC cards, flexible containers, printed circuit boards, printed sheets, and wire covering materials. Body and frame for office equipment or home appliances, decorative plywood, pipes, hoses, synthetic fibers and clothing, plastic molded pellets, urethane materials, packing sheets, packing bands, packing cushioning materials, electrical parts, toys, stationery , Toner, automotive parts (for example, interior parts, bumpers), shredder dust for automobiles or home appliances, ion exchange resins,
Examples include synthetic paper, synthetic resin adhesive, synthetic resin paint, solidified fuel (reduced plastic waste), movie film, polymer absorber, polyethylene for agriculture, plastic for agriculture, and the like. It can be used as it is or after being subjected to predetermined processing as needed. Further, a mixture of these waste plastics and product plastics may be used.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the present invention, as described above, in the refining step, a plastic mainly composed of carbon and hydrogen and another substance for adjusting the specific gravity are charged into substantially the same position in the reaction vessel or the molten metal transport vessel.

Examples of the smelting process include a hot metal pretreatment process such as desulfurization and dephosphorization performed before the converter blowing, a decarburization process in the converter, and a secondary refining performed after the converter blowing. The above-described processing is performed in any one or two or more of these steps.

A plastic mainly composed of carbon and hydrogen is used as a heat source for applying heat. Examples of such a plastic include polypropylene, polyethylene, polystyrene, polyvinyl acetylene, polyvinyl alcohol, and polycarbonate as described above. Most plastics mainly composed of carbon and hydrogen can be mentioned, and it is also possible to use a mixture of two or more plastics. As described above, waste plastics can be suitably used as such a substance containing a plastic mainly composed of carbon and hydrogen, but of course virgin may be used. However, as described above, it is not preferable that a large amount of sulfur, phosphorus, nitrogen or the like becomes a molten steel contamination source, and it is not preferable that a large amount of silicon, aluminum or the like also leads to an increase in slag. Therefore, plastics mainly composed of carbon and hydrogen are selected from those having a small amount of these.

The raw material for adjusting the specific gravity is heavier than the above-mentioned plastic mainly composed of carbon and hydrogen, can effectively prevent the plastic from being scattered, does not adversely affect the molten metal, and contains impurities such as sulfur and phosphorus. Any material that does not have the above can be used, but either one or both of the raw material for refining and the material containing the metal oxide can be used.

Here, the refining raw material refers to a flux mainly used in a refining process such as desulfurization or dephosphorization, and typically includes a calcium oxide source and a magnesium oxide source, such as calcined lime, limestone, slaked lime. , Dolomite, and lightly burnt dolomite can be used.
By using such a raw material for refining, not only the specific gravity adjustment but also a refining reaction can be caused. When limestone, slaked lime, dolomite or the like is used as the specific gravity adjusting substance, the cooling action thereof can be adjusted. That is, limestone, slaked lime, dolomite, etc. easily release gases such as carbon dioxide and water vapor at high temperatures by an endothermic reaction, and in the conventional method, heat of the system is lost and heat loss occurs. Heat loss can be compensated.

When the refining vessel is provided with a gas recovery device, for example, a large amount of carbon dioxide gas generated from limestone is reduced by highly reducible hydrogen gas generated from plastic, and heat is converted to reusable carbon monoxide gas. It is also possible to collect.

The substance containing a metal oxide is used as a solid oxygen source or a metal source.
Mill scale, ironmaking dust, Mn ore, Cr ore, Ni
At least one of the ores can be suitably used. By using such a substance containing a metal oxide, not only the specific gravity can be adjusted but also impurities can be oxidized to be removed or reduced to be recovered as a metal component by reduction. However, an iron oxide source containing a large amount of sulfur or the like is not preferable because it causes contamination of the molten metal. When reducing metal oxides, a reducing agent is required. However, not only carbon but also highly reducing hydrogen gas is generated from plastic, so that plastic effectively acts as a reducing agent.

The reason that the plastic mainly composed of carbon and hydrogen and the substance for adjusting the specific gravity are charged into the reaction vessel or the molten metal transporting vessel at substantially the same position is to allow the substance for adjusting the specific gravity to accompany the plastic. This is because the plastic can be effectively supplied to the molten metal surface or the slag surface without flowing into, for example, an upward flow blown up from the lower part of the container.

As a method of putting them into substantially the same position, they are mixed and kneaded to melt or semi-melt a part or all of the plastic, and are formed into spherical or spheroidal briquettes. Alternatively, extrusion molding into a columnar or prismatic shape and a method of throwing the molded article thus formed by a normal throwing method, for example, throwing in from above are preferable. That is, by forming them into such a molded body, they can be fed integrally, so that they can be fed reliably to the same position.

In particular, when charged into a converter, the rising speed of the converter exhaust gas is as fast as 10 to 20 m / sec, and the plastic component burns or decomposes before the molded body reaches the molten metal surface or the slag surface. In some cases, the combustion heat of the plastic does not heat the molten metal or slag, but when the above-mentioned molded body is manufactured, the apparent density of the molded body is 1100 kg / m.
³ or more, the mass of one compact is 20 g or more, and the shape of the compact is any one of a cylinder, a prism, a sphere, and a spheroid. Surface or slag surface.

The reasons why the apparent density, the mass of one compact, and the shape of the compact are preferable as described above will be described below.

First, the mass of one piece was unified to 30 g, and the apparent density was 800 kg / m ³ , 1100 kg / m ³ ,
An experiment was conducted in which cylindrical molded bodies having three levels of 2200 kg / m ³ were manufactured by extrusion, and each molded body was introduced into a furnace from a furnace opening of a converter having an exhaust gas rising speed of 20 m / sec. As a result, the apparent density was 800 kg /
molding of m ³ will be ejected from the furnace opening with the exhaust gas, the heat of combustion of plastic was not Chakunetsu the molten metal and slag. In contrast, the apparent density is 1100k
g / m ³ of the molded body is 460 per kg of plastic.
A calculated heat surplus of 0 kJ (see the examples described later for the calculated heat surplus), that is, heat was recognized, and a calculated heat surplus of 5200 kJ per kg of plastic was recognized in a molded article having an apparent density of 2200 kg / m ³ . From the results of this experiment, the apparent density of the compact was set to 1100 in order to more reliably reach the melt or slag surface.
It can be seen that it is preferable to be not less than kg / m ³ .

Next, the apparent density is 1100 kg / m ³
And the weight of each is 10g, 20g, 30g, 4g
An experiment was conducted in which a molded article of 0 g in four levels was produced in the same manner, and similarly, the exhaust gas was fed into the furnace from the furnace opening of the converter with a rising speed of 20 m / sec. As a result, it was found that only a calculated thermal surplus of 2000 kJ per 1 kg of plastic was observed in a single molded product having a mass of 10 g, and that 50% or more of the input molded product was discharged together with exhaust gas. On the other hand, when the mass of one molded body was 20 g or more, a calculated thermal surplus of about 4600 kJ per kg of plastic was observed. From these experimental results, in order to more reliably reach the molten metal surface or slag surface,
It is understood that it is preferable that the mass of one molded body be 20 g or more.

The shape of the compact is as follows. The aerodynamic drag coefficient (also referred to as “shape coefficient”) of a molded body differs depending on the shape of the molded body. As the aerodynamic resistance coefficient increases, the molded body is affected by the upward flow and is easily discharged from the furnace. In the cylindrical shaped body used in the above test, the aerodynamic drag coefficient is about 1.0. That is, if the aerodynamic drag coefficient is a shape of 1.0 or less, a calculated thermal surplus equal to or greater than the above test can be expected. The prismatic body has the same aerodynamic drag coefficient as the cylindrical body, and is about 0.5 for a spherical body and a spheroid. That is, when the molded body is a prism, a sphere, or a spheroid, the molded body can reach the molten metal surface or the slag surface in the same manner as in the above-described test in which the molded body is a cylindrical body.

As a method of putting a plastic mainly composed of carbon and hydrogen and another substance for adjusting specific gravity into substantially the same position, as described above, a plastic mainly composed of carbon and hydrogen and a substance for adjusting specific gravity are used. Is not processed into a molded body with other substances, for example, using a lance, nitrogen, argon,
It is also possible to use an injection in which these are injected together with the accompanying flow such as oxygen. In this case, it is preferable to feed them simultaneously using a single lance. Further, these may be blown from a blowing hole provided at the bottom of the reaction vessel or the molten metal transport vessel. This blowing can be performed using a gas blowing device formed at the bottom of these containers as a carrier flow.

[0028]

Embodiments of the present invention will be described below. (Example 1) In this example, Mn was used as a specific gravity adjusting substance.
An example using ore will be described. First, Mn ore is sintered to reduce the degree of oxidation of Mn (hereinafter referred to as Mn ore sintered powder), and polyethylene and polypropylene are respectively 3 mass% and 17 mass% of the whole.
Mixed and kneaded with the plastic compounded so that
Individual mass is 30-50g, apparent density is about 2200k
A spheroidal briquette of g / m ³ was prototyped. Next, this briquette was supplied from a feeder onto the molten metal during converter blowing, and the Mn ore yield during operation and the utilization of combustion heat of the contained plastic were evaluated.

In the test, a system for accurately estimating the end point temperature in consideration of the history of the converter furnace body, the temperature of the charge, the amount of the charge, and the reaction heat in the furnace was used. This system is based on the assumption that Mn ore containing no plastic is originally used, so the pure content of Mn ore in the briquette subjected to the test is calculated, and the plastic etc. effectively acts as a heat source. If this is the case, the temperature at the end point will be high, so that the amount of iron ore to be introduced at the end of blowing to increase the temperature will increase in accordance with the amount of the blended plastic.

FIG. 1 is a graph showing the relationship between the amount of plastic compounded on the horizontal axis and the amount of heat addition, that is, the heat surplus converted from the amount of iron ore used for temperature adjustment, on the vertical axis. is there. As the amount of plastic on the horizontal axis, a value obtained by dividing the amount of plastic charged by the amount of hot metal charged into the converter was used. Since the heat of combustion of plastics varies depending on the substance, the amount used is based on the calorific value of a typical substance. In addition, since the thermal calculation was performed on the assumption that no plastic was charged, the actual temperature of the molten steel was higher than the estimated value due to the heat of combustion of the plastic. Therefore, it was necessary to lower the end point temperature as calculated, and since iron ore was used as the coolant, the heat surplus was calculated from the cooling capacity. From this figure, it can be seen that as the amount of the blended plastic increases, the heat surplus at the end point, that is, the thermal allowance increases, and as a result, a large amount of iron ore was introduced at the end of blowing. The heat surplus increased with an increase in the amount of plastics and the like, and the slope thereof almost coincided with the temperature rising ability of the plastics calculated. In other words, it was confirmed that this heat surplus coincided with the heat amount obtained by excluding the heat of decomposition of the plastic and the sensible heat loss to the generated gas from the heat of combustion of the plastic.

From the above, by using the Mn ore as a substance for adjusting the specific gravity and putting it at substantially the same position as the plastic, the plastic can be effectively supplied to the molten metal surface and effectively used as a heat source, and It was confirmed that the plastic can provide the heat required for the reduction of Mn ore.

Embodiment 2 In this embodiment, a case where calcined lime and iron ore are used as a specific gravity adjusting substance and the present invention is applied to a dephosphorization treatment will be described. First, a briquette was manufactured by blending a mixture of calcined lime and iron ore at a weight ratio of 1: 1 and a plastic mainly composed of polypropylene, and melted in a 500 kg melting furnace, a small test furnace, of 300 kg. Of hot metal. In addition, plastic was added to 100 parts by weight of the mixture of calcined lime and iron ore.
It was blended so as to be 0 parts by weight. For comparison, the case where calcined lime alone was added (conventional) was also tested. In order to simulate the dephosphorization reaction in the hot metal pretreatment, during the dephosphorization process, the molten metal is stirred with Ar gas from the bottom of the vessel, and at the same time, oxygen is blown from above the molten metal surface, and oxygen is always supplied to the molten metal upper surface. Was.

FIG. 2 shows the results. FIG. 2 is a diagram showing the results of measuring the phosphorus concentration in the hot metal over time by taking the refining time on the horizontal axis and the phosphorus concentration in the hot metal on the vertical axis. The initial phosphorus concentration in the example was about 0.1 mass%. As shown in this figure, the phosphorus concentration decreases with the passage of time, but in the case of the present example, the dephosphorization behavior was observed in a shorter time than in the conventional case of the comparative example, and the dephosphorization reaction was performed in a shorter time. It was clear that we would end. It can be considered that this is a time difference until the calcined lime that has been introduced turns into slag and functions effectively as a dephosphorizing agent. That is, in the case of the present example, the dephosphorization reaction further progressed because polypropylene was used as a heat source. At the time of dephosphorization, an oxygen source (generally iron oxide in the slag) contained in the slag or the like is required. Therefore, when the plastic comes into contact with the slag, the reducing gas generated from the plastic reduces iron oxide in the slag, and there is a concern that dephosphorization may be inhibited, but the reducing gas reacts with the atmosphere or the oxygen source in the slag. Then, the carbon monoxide gas was converted to carbon monoxide gas, but after the heat was converted to slagging energy, it easily separated from the slag and desorbed out of the system in the gas phase, so that no dephosphorization inhibition was observed.

(Embodiment 3) In this embodiment, a case will be described in which calcined lime is used as a specific gravity adjusting substance and the present invention is applied to a desulfurization treatment. First, briquettes were manufactured by blending calcined lime and a plastic mainly composed of polypropylene, and were added to 300 kg of hot metal melted in a 500 kg melting furnace as a small test furnace. In addition, calcined lime and plastic were mixed at a weight ratio of 4: 1 for production. For comparison, the case where calcined lime alone was added (conventional) was also tested.

FIG. 3 shows the results. FIG. 3 is a diagram showing the results of measuring the sulfur concentration in hot metal over time by taking the refining time on the horizontal axis and the sulfur concentration in the hot metal on the vertical axis.
The initial sulfur concentration was about 0.03 mass%.
As shown in this figure, although the sulfur concentration decreases with the passage of time, in the case of the present example, desulfurization behavior was observed in a shorter time than in the conventional case of the comparative example, and the desulfurization reaction was completed in a short time. It became clear. It can be considered that this is a time difference until the calcined lime that has been introduced turns into slag and functions effectively as a desulfurizing agent. That is, in the case of the present example, the desulfurization reaction proceeded more because polypropylene was used as a heat source.

From the above Examples 2 and 3, by introducing a refining agent as a substance for adjusting the specific gravity into substantially the same position as the plastic, the plastic is effectively supplied to the molten metal surface and effectively used as a heat source. It was confirmed that not only the temperature drop near the refining agent introduction position was compensated, but also slagification was promoted, and the reaction speed and the reached impurity level exhibited characteristics superior to those of the conventional one.

Embodiment 4 In this embodiment, an example using Mn ore as a substance for adjusting specific gravity will be described. First,
Mn ore sintered powder and a plastic compounded so that the total of polyethylene and polypropylene is about 85 mass% of the whole are mixed and kneaded, and the mass of one piece is 50 to 55.
g, a cylindrical extruded body having an apparent density of about 1100 kg / m ³ was produced. Next, this compact was supplied from a feeder onto the molten metal during converter blowing, and the Mn ore yield during operation and the utilization of combustion heat of the contained plastic were evaluated.

In the test, the same converter as in the first embodiment was used, and the heat surplus due to the heat of combustion of the plastic was calculated in the same manner as in the first embodiment. As a result, the heat surplus due to the combustion heat of the plastic was the same as in Example 1, and the heat surplus when 3 kg of plastic was injected per ton of hot metal was 42000 kJ / T.

As described above, by using Mn ore as a substance for adjusting the specific gravity and throwing it into substantially the same position as the plastic, the plastic is effectively supplied to the molten metal surface or the slag surface, whereby the plastic is effectively used as a heat source. Available, and M
It was confirmed that the heat required for the reduction of n ore could be provided.

[0040]

As described above, according to the present invention,
In the refining process, a plastic mainly composed of carbon and hydrogen is introduced as a heat source for applying heat, so that the heat source can be reduced in impurities. In addition, by introducing the substance for adjusting the specific gravity into substantially the same position as the plastic mainly composed of carbon and hydrogen, the plastic mainly composed of carbon and hydrogen can be effectively used without flowing into the upward flow blown up from the lower part of the container. Can reach the molten metal surface or the slag surface. Therefore, heat can be efficiently added.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of mixed plastic and the heat surplus calculated from the amount of iron ore used for temperature adjustment in Example 1.

FIG. 2 is a graph showing the results of measuring the phosphorus concentration in hot metal over time in Example 2 in comparison with the conventional method.

FIG. 3 is a graph showing the results of measuring the sulfur concentration in hot metal over time in Example 3 in comparison with the conventional method.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C21C 7/04 C21C 7/04 AT 7/072 7/072 S C22B 1/244 C22B 1/244 (72 Inventor Yoshiaki Tabata 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Akihiko Inoue 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan 1-2 Nihon Kokan Co., Ltd. (72) Invention Person Tadaaki Hino 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Shou Izaka 1-2-1, 1-2, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 4K001 AA10 BA02 BA14 BA24 CA26 4K013 DA09 EA01 EA03 EA29 EA36 4K014 AB02 AB03 AB04 AB28 AC00 AC16 4K070 AB03 AB05 AB06 AB17 AB18 AC12 AC13 AC14 AC31 AC36 BB08 CE04 EA10 EA11

Claims (9)

[Claims] In a refining process, a plastic mainly composed of carbon and hydrogen and another substance for adjusting specific gravity are charged into substantially the same position in a reaction vessel or a molten metal transport vessel. Steelmaking method. 2. The steelmaking method according to claim 1, wherein one or both of a material for refining and a material containing a metal oxide are used as the substance for adjusting the specific gravity. 3. The refining raw material is at least one of calcined lime, limestone, slaked lime, dolomite, and lightly calcined dolomite.
3. The method according to claim 2, wherein the method is a seed. 4. The substance containing a metal oxide includes iron ore, mill scale, ironmaking dust, Mn ore, Cr ore,
3. The steel making method according to claim 2, wherein at least one kind of Ni ore is used. 5. A molded body is produced from the plastic mainly composed of carbon and hydrogen and a substance for adjusting specific gravity, and the molded body is charged into the reaction vessel or the molten metal transport vessel. The steel making method according to any one of claims 1 to 4. 6. The method according to claim 5, wherein the compact has an apparent density of 1100 kg / m ³ or more. 7. The molded product is a cylinder, a prism, a sphere,
The steelmaking method according to claim 5, wherein the steelmaking method has one of spheroids. 8. The steelmaking method according to claim 5, wherein each of the compacts has a mass of 20 g or more. 9. The plastics mainly composed of carbon and hydrogen and a substance for adjusting specific gravity are injected into the reaction vessel or the molten metal transport vessel at substantially the same position by injection. The steelmaking method according to any one of claims 1 to 4.