JP7285103B2 - Method for producing iron-making raw materials and method for producing pig iron - Google Patents

Description

The present invention relates to a method for producing iron-making raw materials and a method for producing pig iron using the iron-making raw materials.

In steelmaking, iron ore and coke are generally placed in a blast furnace and the coke is burned at high temperatures to dissolve and reduce iron oxides in the iron ore. To obtain steel, it is necessary to combine iron and carbon, and coke is also the source of that carbon.

Further, Patent Documents 1 to 5 and the like describe mixing iron ore powder and iron sand with a binder material such as phenolic resin, forming and heating the mixture to obtain a raw material for iron manufacturing in the form of pellets. The iron-making raw materials are put into a blast furnace to make iron.

JP-A-6-240372 JP 2017-75348 A JP 2015-189982 A JP-A-2002-322514 JP-A-53-43018

Conventional blast furnace ironmaking methods require large amounts of high-quality coal, such as coke, to be consumed. However, high quality coal is a limited resource and is becoming expensive. Furthermore, iron ore, which is a raw material for iron manufacturing, also requires large lumps, and the use of powdered iron ore is also desired.

Patent Documents 2 to 5 describe mixing iron ore with a lignin sulfonate binder and sintering the mixture to produce sintered ore for charging into a blast furnace. However, these also require coal for the production of calcined ore and the subsequent ironmaking process. Furthermore, it is desirable to obtain high quality pig iron.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing iron-making raw materials and a method for producing pig iron, which can produce iron without using coal and can produce high-quality pig iron.

In order to solve the above problems, the method for producing ironmaking raw materials of the present invention includes hematite powder and lignin sulfonate in a weight ratio of 0.1 to 0.15 with respect to the hematite powder. A mixture containing a binder and water is pressure-molded at a pressure of 50 kgw/cm ² or more and 60 kgw/cm ² or less, and heated to a temperature of 500° C. or more to solidify. In particular, we use a multi-axis electric sintering machine equipped with a cylindrical mold that holds the material, a member that presses the mold, and electrodes that contact and electrify the mold from multiple directions to the side of the mold to heat the mold. Then, a mixture containing hematite powder, a binder containing lignin sulfonate in a weight ratio of 0.1 or more and 0.15 or less to the hematite powder, and water is placed in a mold and the mixture is charged to 50 kgw/cm ² or more. It is preferable to solidify by heating and sintering at a temperature of 500° C. or higher for 10 to 15 minutes while applying a pressure of 60 kgw/cm ² or less to the mold.

Further, in the method for producing pig iron of the present invention, pig iron is produced by heating the iron-making raw material obtained by the above-described method for producing iron-making raw material in an electric furnace without using coal.

According to the method for producing iron-making raw materials and the method for producing pig iron of the present invention, high-quality iron-making raw materials can be obtained, and iron can be produced without using coal such as coke. This invention makes it possible to produce high-purity, high-quality pig iron.

4 is a flow chart showing an example of a method for producing pig iron; 1 is a longitudinal sectional view conceptually showing the basic structure of a multi-axis electric sintering machine; FIG. It is the same top view.

A mode for carrying out the present invention will be described. 4 is a flow chart showing an example of a method for producing pig iron;

First, a method for manufacturing iron-making raw materials will be described. A binder containing iron ore powder and lignin sulfonate is mixed with water. Here, the binder has lignin sulfonate as a main component. In this example, Sanex (registered trademark), which is a binder for fine ore briquettes manufactured by Nippon Paper Industries, was used. Moreover, hematite ore was used as iron ore. Here, the amount of binder is set so that the weight ratio of lignin sulfonate to iron ore is 0.1 or more and 0.15 or less. It has been found that by adjusting the content to this range, it becomes possible to manufacture iron without using coal, and to produce high-quality pig iron. In particular, when the lignin sulfonate is 0.1 or more, the quality of iron-making raw materials and pig iron obtained is high. However, it was also found that even if the amount exceeded 0.15, no further improvement in quality was observed. In particular, a formulation with a weight ratio of approximately 0.12 is most preferred.

A mixture containing this iron ore and a binder is pressure-molded into a sintered ore shape such as a disk shape or a pellet shape, and sintered. The steps of pressure molding and sintering may be performed simultaneously using a multi-axis current sintering machine. As a result, it is possible to obtain raw materials for ironmaking in a short period of time in one step. Alternatively, after pressure molding, the molding may be heated in a furnace to be sintered. In this case, mass production can be performed with inexpensive equipment.

The pressure during pressure molding is preferably about 50 kgw/cm ² or more and 60 kgw/cm ² or less, and is 50 kgw/cm ² in this example. Moreover, in Patent Documents 1 to 5, sintering is performed at a low temperature, but in the present invention, the sintering temperature must be 500° C. or higher. As a result, it is possible to obtain an excellent iron-making raw material with a small ignition loss, and to produce high-quality pig iron. Pressing and sintering may be carried out simultaneously as well as in separate steps. In particular, we use a multi-axis electric sintering machine equipped with a cylindrical mold that holds the material, members that pressurize it, and electrodes that heat the mold by contacting and energizing the side surfaces of the mold from multiple directions. preferably. This made it possible for the first time to commercialize the iron-making raw material of the present invention. FIG. 2 is a longitudinal sectional view conceptually showing the basic structure of the multi-axis electric sintering machine, and FIG. 3 is a plan view of the same. A multi-axis electric sintering machine 1 has a cylindrical mold 2 that accommodates a material x. In this example the mold 2 is cylindrical and confines the material with an upper punch 3 and a lower punch 4 . The lower punch 4 is vertically movable. The material x inside the mold 2 is pressed by a mold pressurizing rod 5 that presses the upper punch 3 and a mold lift rod 6 that vertically moves the lower punch. Electrodes 7 are also provided outside the sides of the mold. The electrodes are provided with a pair of electrodes 7a and 7b facing each other on the same axis and a pair of electrodes 7c and 7d facing each other on an axis perpendicular thereto. These electrodes 6 can energize the mold 2 to heat the material x therein. The mixture containing the aforementioned iron ore and binder is put into this mold, and the material x is heated while being pressurized. In this example, heat sintering was performed at 550° C. for 10 to 15 minutes to produce raw materials for ironmaking. When a test based on JIS A1226 was conducted on the iron-making raw material of this example at the Ehime Prefectural Industrial Technology Research Institute, the ignition loss was 3.26%. Within the scope of the present invention, all of them were 3.50% or less, which satisfied the standards required for iron-making raw materials.

Next, a method for producing pig iron using this iron-making raw material will be described. Ironmaking using this raw material for ironmaking can be carried out in a blast furnace or a cupola, but it is preferable to use an electric furnace. There is no need to use coke, the ironmaking raw material of the present invention is charged and melted from about 1200°C and melted at 1500°C.

この測定では、Ｆｅ成分は、質量でもモルでも９８％を超えており、極めてＦｅ成分の高い高品質な銑鉄が得られることが確認できる。また、この試験以外でも本願発明の範囲内であれば、９６％以上の鉄成分率が得られている。 The obtained pig iron was subjected to component analysis using an energy dispersive X-ray fluorescence spectrometer at the Ehime Prefectural Industrial Technology Research Institute. Measurement conditions and measurement results are shown in Table 1 below.

In this measurement, the Fe content exceeds 98% both in mass and in moles, and it can be confirmed that high-quality pig iron with an extremely high Fe content can be obtained. Besides this test, an iron content of 96% or more was obtained within the scope of the present invention.

As described above, pig iron can be produced without using coal such as coke at all in the production of ironmaking raw materials and in the subsequent production of pig iron. Coke is a limited natural resource, and the countries from which it can be imported are limited, so the supply tends to be unstable, but the present invention solves such problems. Moreover, it is possible to manufacture steel using small-scale, inexpensive equipment such as electric furnaces and cupolas. The resulting pig iron is of high quality with a high iron content.

1. Multi-axis current sintering machine2. Type 3. Upper punch 4. Lower punch5. 6. Mold pressure bar. mold lift bar7. electrode x. material

Claims (2)

Using a multi-axis electric sintering machine equipped with a cylindrical mold for containing the material, a member for pressing it, and an electrode for heating the mold by contacting and energizing the side surface of the mold from multiple directions,
A mixture containing hematite powder, a binder containing lignin sulfonate in a weight ratio of 0.1 or more and 0.15 or less to the hematite powder, and water is put into a mold and the mixture is put into a mold with a weight of 50 kgw/cm ² or more and 60 kgw/cm2. A method for producing a raw material for ironmaking, comprising applying electricity to a mold with an electrode while pressurizing at a pressure of 500° C. ^or higher, and heating and sintering at a temperature of 500° C. or higher for 10 to 15 minutes to solidify. A method for producing pig iron by heating raw materials for iron making obtained by the method for producing raw materials for iron making according to claim 1 in an electric furnace without using coal.

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