JP2002088417A - Method and apparatus for rapid measurement of reduced iron metallization rate and method of using the apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] By developing an apparatus and a method for quickly measuring the metallization ratio of dust pellets, it becomes possible to predict the amount of carbon material and oxygen in a melting-only converter. Aim to increase operating unit consumption and stabilize operation. SOLUTION: In the metallization rate measuring apparatus for dust pellets mainly composed of iron oxide and metallic iron and composed of other unavoidable impurities, a cylinder for filling the dust pellets is provided, and the dust pellets can be excited on the outer periphery of the cylinder. And a power supply for exciting the coil, and a measuring unit for measuring the voltage and current of the excited coil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a metallization ratio of reduced iron obtained by reducing dust and the like generated in an ironworks, an apparatus therefor, and a method for using the apparatus.

[0002]

2. Description of the Related Art A method of reusing reduced iron obtained by reducing dust generated in an ironworks is known. For example, as disclosed in Japanese Patent Application Laid-Open No. 2000-45012, iron-containing cold material, carbonaceous material, and oxygen are supplied to a melting-only converter existing in a seeding bath, and the required amount of seeding metal in the melting-only converter is determined. In the converter steelmaking method of obtaining the high-carbon molten iron of the total amount of required refining in another refining dedicated converter, and obtaining the required component molten steel by oxygen refining in the dedicated refining converter using this high-carbon molten iron as a raw material,
Dust generated in a melting furnace and a smelting furnace is coated with carbon material and agglomerated, heated at a high temperature in a pre-reduction furnace and pre-reduced using the interior carbon material as a reducing material, and then a part of the iron-containing cold material in a high temperature state Is supplied to a converter dedicated to melting where seed water is present and reused.

[0003] However, when the pre-reduced dust pellets are used in a converter dedicated to melting in the next step in a high temperature state, if the metallization rate of the pre-reduced dust pellets cannot be measured quickly, There was a problem that it was impossible to predict the supply amounts of the carbon material and oxygen in the melting converter, and it was not possible to obtain a good unit consumption of coal in the melting furnace. In addition, the metallization rate of the pre-reduced dust pellets may fluctuate greatly, which causes a problem that the supply amounts of the carbonaceous material and oxygen in the melting furnace are not constant and stable operation cannot be obtained.

[0004] On the other hand, conventionally, as a method of measuring the metallization ratio of reduced iron, a method of quantitatively analyzing a sample and applying T.I. Fe and M. It is general to calculate and determine from the value of Fe.
However, there is a problem that it takes more than one day until the judgment is made, and there is a problem that the measurement result cannot be made in time when the reduced iron is used in the melting furnace in a high temperature state.

As a method for quickly measuring the metallization ratio, Japanese Patent Publication No. 58-24484 discloses a dynamic measurement and control method of the metallization ratio in direct reduction steelmaking. This is a method of estimating the metallization rate from the measured values of the change in the total oxygen amount in the gas and the change in the reducing gas amount. However, in this method, equipment for measurement is complicated and expensive. In addition, when the brand of the raw material to be reduced changes, the relationship between the change in the total amount of oxygen in the gas and the change in the amount of reducing gas shifts. It becomes.

[0006]

In the following description, reduced iron pellets produced from steelmaking dust will be described as typical examples of reduced iron. However, reduced iron obtained by reducing pellets produced from iron ore powder, or reduced iron, The present invention is also applicable to briquettes of the obtained iron. Dust generated in a converter dedicated to melting or a converter dedicated to refining supplies pure oxygen,
For example, most of the iron is oxidized due to the top blowing. To reduce and melt iron oxide, for example, ferrous oxide, theoretically requires about four times the calorific value of pure iron. Therefore, the agglomerated dust pellets containing iron oxide are preliminarily reduced, and the reduced dust pellets are kept in a high-temperature state, for example, when recycled in a high-temperature state in a melting-only converter, the reduced dust used for recycling. If the metallization rate of the pellets could not be predicted quickly, there was a very large change in the heat of melting due to the change in the metallization rate, and it was not possible to predict the supply amounts of the carbonaceous material and oxygen in the converter dedicated to melting.

In the present invention, an object of the present invention is to develop an apparatus and a method for quickly measuring the metallization ratio of dust pellets. As a result, it is possible to predict the supply amounts of the carbon material and oxygen in the converter exclusively for melting, and it is expected that the unit consumption of coal and the operation stabilization of the converter exclusively for melting can be improved.

[0008]

The gist of the present invention is as follows. (1) In a method for measuring the metallization ratio of reduced iron composed mainly of iron oxide and metallic iron and composed of other unavoidable impurities,
The above-described reduced iron is filled in a cylinder, and the metallization ratio of the reduced iron is calculated from the current value when the filled reduced iron is excited to a constant voltage by a coil from the outside of the cylinder and the weight of the filled reduced iron. Method for rapid measurement of metallization rate of reduced iron. (2) The method according to (1), wherein a correction is made to the metallization ratio calculated from the current value and the weight of the charged reduced iron according to the temperature of the reduced iron. (3) The method according to (1) or (2), wherein the dust generated in the steelworks is provided with a carbonaceous material inside and agglomerated, and dust pellets reduced by a high-temperature heating furnace are used. (4) An apparatus for measuring the metallization rate of reduced iron comprising iron oxide or metallic iron as a main component and other unavoidable impurities, comprising: a measuring section for the reduced iron; a cylinder filled with the reduced iron; A coil capable of exciting the reduced iron, a power supply for exciting the coil, a measuring unit for measuring the voltage and current of the excited coil, and measuring the weight of the reduced iron and the measured current value. An apparatus for rapidly measuring the metallization ratio of reduced iron, comprising a calculation unit for calculating the metallization ratio based on the calculation. (5) a temperature measuring unit for measuring the temperature of the reduced iron; and a calculating unit for correcting the metal metallization ratio calculated based on the weight and the current value of the reduced iron at the measured temperature. The apparatus according to (4). (6) The apparatus according to (4) or (5), wherein the dust generated in the steelworks is made of carbon material and is agglomerated, and dust pellets reduced by a high-temperature heating furnace are used. (7) In a method in which carbon material is put inside a dust generated in an ironworks and agglomerated, and dust pellets subjected to a reduction treatment by a high-temperature heating furnace are fed into a melting furnace in the next step,
The metallization rate of the reduced dust pellet is measured by the apparatus according to any one of (4) to (6), and the supply amounts of the carbon material and oxygen in the melting furnace in the next step are determined based on the measured metallization rate. A method of using a device for rapidly measuring the metallization rate of reduced iron, which is characterized in that it is determined. (8) The method according to any one of (4) to (6), wherein the dust generated in the steel mill is made to agglomerate with carbonaceous material inside, and reduced by a high-temperature heating furnace. A method of using a reduced iron metallization rate rapid measuring device, characterized in that a metallization ratio is measured by a method, and operating conditions of a high-temperature heating furnace are determined based on the measured metallization ratio.

Here, the basic principle of the invention having the above configuration will be described in detail. The metallization ratio in the present invention is represented by the following equation. Metallization rate (%) = (metallic iron content in reduced iron) / (total iron content in reduced iron) × 100 In the reduced iron, carbon other than iron and inevitable impurities such as Zn, Ni, Cr, Cu , Sn etc. are 0.1wt%
To some extent, there is no problem even if they are mixed in the present invention.

[0010] The reduced iron in the present invention is generated in an integrated steel mill having a blast furnace, an integrated steel mill using cold iron as a raw material, an electric furnace process steel mill, an industrial waste treatment plant such as a scrap car, a home appliance, and the like. Any reduced iron can be used as long as it is a reduction treatment of dust. For example, as disclosed in Japanese Patent Application Laid-Open No. 2000-45012, iron-containing cold material, carbonaceous material, and oxygen are supplied to a melting-only converter existing in a seeding bath, and the required amount of seeding metal in the melting-only converter is determined. In the converter steelmaking method of obtaining the high-carbon molten iron of the total amount of required refining in another refining dedicated converter, and obtaining the required component molten steel by oxygen refining in the dedicated refining converter using this high-carbon molten iron as a raw material, There are dust pellets and the like in which carbon material is agglomerated with dust generated in a melting furnace and a smelting furnace, which is heated at a high temperature in a pre-reduction furnace and the interior carbon material is used as a reducing material. The dust pellets obtained as described above are supplied as a part of the iron-containing cold material to a melting-only converter in which seed water exists as a part of the iron-containing cold material, and reused. In addition to the above-mentioned converter dedicated to melting, it is also within the scope of the present invention to mix reduced iron into iron ore of a general blast furnace and charge the reduced iron into an electric furnace for reuse.

Hereinafter, as a typical example of reduced iron, carbon materials are made to agglomerate by incorporating carbon materials into dust generated in a melting furnace and a smelting furnace, and heated at a high temperature in a pre-reduction furnace to use the interior carbon materials as a reducing material. The reduced dust pellets will be described as an example. FIG. 1 is an explanatory diagram of the measurement principle of the metallization ratio measuring device according to the present invention. First, the basic configuration of the present apparatus will be described with reference to FIG. A coil 3 is applied to a cylinder 2 filled with dust pellets 1 in the form of a solenoid, and an AC stabilized power supply 4 for applying a stable voltage to the coil 3, a voltmeter 5 for measuring the voltage and current at that time, and an ammeter 6. FIG. 2 is an explanatory diagram of the electric circuit of FIG. 1, and r in FIG.
It is the electric resistance (Ω) of the coil 3 and L indicates the inductance (H) of the coil. When an AC voltage V is applied to this electric circuit, a circuit current i flowing through the AC circuit is expressed by the following equation (1) according to circuit theory. i (current) = V / {r ² + (ω · L) ² } (1) ω: each frequency (rad / s)

Next, the reason why the metallization ratio can be measured will be described. When a ferromagnetic material is loaded into the cylinder 2 excited by the coil 3 (hereinafter referred to as the inside of the coil 3), the ferromagnetic material is very easily magnetized, and the average magnetic resistance R in the coil 3 decreases. Change in direction. And easiness of magnetization is expressed in relative permeability mu _s, the magnetoresistance R larger this value is smaller, i.e., inversely proportional _{(R = K 1 / μ s} , K 1 is a constant) It is known. The inductance L in the electric circuit of FIG.
It is known that the relationship is inversely proportional to the magnetic resistance R (L = K ₂ / R, K ₂ is a constant), that is, the relationship between the inductance L and the relative magnetic permeability _μs is proportional (L = K ₂ / R). K ₃ ·
μ _s and K ₃ are constants). Therefore,
By substituting this relationship into equation (1), the following equation (2) is obtained. i ^{(current) = V / √ {r 2} + (ω · K 3 · μ s) 2} ... (2)

Each frequency ω in the above equation (2) can be handled as a constant if the power supply frequency of the stabilized AC power supply 4 is determined. Therefore, ω · K ₃ = K (K is a constant) Further, the equation (2) can be transformed into the following equation (3). i (current) = V / {r ² + (K · μ _s ) ² } (3)

That is, the dust pellet 1 containing pure iron, which is a ferromagnetic substance, is charged into the coil 3 so that the coil 3
The average relative magnetic permeability μ _s changes within
As can be understood from the equation (3), it is finally possible to detect a change in the circuit current i. In addition, since the relative permeability _μs changes in accordance with the change in the content of pure iron in the dust pellets, that is, the change in the metallization rate, it is expected that the metallization rate can be measured.

However, as a result of the actual measurement, it was found that the error was extremely large only with the circuit current i and was not practical. In this regard, the volume occupied by the dust pellets in the coil 3 differs between the case where the average particle size of the dust pellet is large and the case where the average particle size of the dust pellet is small even if the metallization ratio is the same. It was noticed that the relative magnetic permeability μ _s was changed, and as a result, a large error was generated. Therefore, it was conceived that it was necessary to correct the volume occupied by the dust pellet in the coil 3, but since the measurement of the volume could not be easily performed, we should correct the volume based on the quality of the population. Considering that the constant is constant, the idea of performing the correction by the weight was conceived, and finally the measurement of the metallization rate that can be practically used was enabled by the correction of the circuit current i and the weight value of the filled dust pellet. It has also been found that it is very desirable from the viewpoint of improving accuracy by previously performing a metallization ratio measurement by quantitative analysis and obtaining an estimation formula by regression calculation with the above current value and weight value.
For example, as the estimation formula, a formula like the formula (4) is given. Metallization ratio (%) = A + B × i + C × W (4) i: current, W: weight of dust pellet A, B, C: constant (regression coefficient) Note that equation (4) is a linear equation. Although this is an example, a quadratic or higher order equation can be used to further improve the estimation accuracy.

In order to effectively obtain the effects of the present invention, the particle diameter of the dust pellet is desirably 8 to 12 mm. Preferably it is 4 to 14 mm. Furthermore, it is desirable that the shape of the dust pellets be as uniform as possible. The ratio of the length of the dust pellet loaded to the cylinder to the length of the coil portion cylinder is preferably 65 to 100%. Preferably 30 to
115%.

In consideration of a change in relative magnetic permeability _μs due to a change in the temperature of the dust pellet, the temperature of the dust pellet is measured, and the circuit current i and the metallization rate estimated by weight value correction are corrected to improve accuracy. More desirable. Further, as for the method of determining the power supply frequency, a low-frequency power supply device is required to uniformly excite the dust pellets, but it can be said that realization at a commercial frequency is desirable in terms of cost.

Here, the configuration of the apparatus of the present invention will be described. FIG. 3 is an example of a device configuration of a metallization ratio measuring device according to the present invention. The present apparatus is provided with a weighing unit 7 for measuring the weight of the dust pellet 1, a cylinder 2 for filling the dust pellet 1, and a coil 3 for exciting the filled dust pellet is wound around the outside of the cylinder 2. . In principle, a non-magnetic material is used as the material of the cylinder 2, and PVC, plastic, and the like are desirable. Preferably, a nonmagnetic metal such as copper or lead may be used. Further, the AC stabilized power supply 4 for exciting the coil 3 is provided, and the voltmeter 5 for measuring the excited voltage is provided. Further, an ammeter 6 for measuring a current when the coil is excited is provided. The arithmetic unit 9 for calculating the metallization ratio of the dust pellet 1 based on the current value and the weight measured from the ammeter 6 and the weighing unit 7 is provided. Moreover,
In order to improve the estimation accuracy of the metallization ratio, it is within the scope of the present embodiment to provide the temperature measuring unit 8 for measuring the temperature of the dust pellet 1.

With the above apparatus, it is possible to quickly measure the metallization ratio of dust pellets. The quick measurement of the metallization rate of dust pellets made it possible to predict the required carbon material and oxygen content in a melting-only converter when recycling it at a high temperature in a melting-only converter. Also,
It is also possible to improve the unit consumption of coal and stabilize the operation of the converter dedicated to melting. In addition to the case of the melting-only converter, it is also within the scope of the present invention to predict the required amount of heat when reusing dust pellets in an electric furnace.

Further, by rapidly measuring the metallization ratio of the dust pellets, the carbon material is provided inside the dust and agglomerated,
In the method in which the pre-reduction furnace is heated to a high temperature and the interior carbonaceous material is used as a reducing material and the reduction treatment is performed in the high-temperature heating furnace, the operating conditions such as the atmosphere of the high-temperature heating furnace, the gas supply amount, the sealing property in the furnace, and the method of charging the dust. Is also within the scope of the present invention.

[0021]

EXAMPLE The metallization ratio of dust pellets was measured using an apparatus as shown in FIG. This device includes a cylinder 2 for filling dust pellets 1, and a coil 3 for exciting the dust pellets filled outside the cylinder 2 is wound. The coil 3 is excited by an AC stable power supply 4. The excitation voltage was measured by a voltmeter 5 and the AC stabilized power supply 4 was controlled at 5V. Dust pellets preheat-reduced by heating at a high temperature in a prereduction furnace and using the interior carbonaceous material as a reductant were sampled. Ten of the pellets were weighed by a weighing unit 7, and the temperature was measured by a temperature measurement unit 8. And the current was measured by the ammeter 6. Each of these measurements is 1
9.1 g, 23 ° C., 4.08 A. The calculation unit 9 measured each of the measured values as a metallization ratio of 90.5%. From the weighing of the pellets to the measurement of the metallization ratio, it took less than one minute. Using these measured values, the unit of coal was determined and operated in the converter dedicated to the melting furnace. The result of the quantitative analysis performed at a later date was a metallization ratio of 90.1%.

On the other hand, as a conventional method of comparison, when the measurement result of the metallization rate is not used, the lower limit of the metallization rate assumed in the metallization rate of the manufactured reduced iron (dust pellets after preliminary reduction) is considered. The coal unit consumption was determined based on the conversion rate, and operations were started. Comparing the method of the present invention with the conventional method, it was possible to reduce the coal unit consumption of the converter exclusively for melting by 8%. In addition, the composition of the manufactured hot metal was stable and stable.

[0023]

According to the present invention, by developing an apparatus and method for quickly measuring the metallization ratio of dust pellets according to the present invention, it becomes possible to predict the amount of carbonaceous material and oxygen in a melting-only converter.
It has become possible to improve the unit consumption of coal and stabilize the operation of the converter dedicated to melting.

[Brief description of the drawings]

FIG. 1 shows the principle of measuring the metallization ratio in the present invention.

FIG. 2 shows an equivalent circuit of FIG.

FIG. 3 shows an example of an apparatus configuration according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dust pellet 2 Cylinder 3 Coil 4 AC stable power supply 5 Voltmeter 6 Ammeter 7 Weighing part 8 Temperature measuring part 9 Operation part

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01N 33/20 G01N 33/20 E (72) Inventor Yasuhiro Mayumi 1-Fuji-cho, Hirohata-ku, Himeji-shi, Hyogo New Inside the Hirohata Works of Nippon Steel Corporation (72) Inventor Kazuo Onuki 1Fuji-cho, Hirohata-ku, Himeji-shi, Hyogo Prefecture AA22 BA01 CA07 DA02 EA04 EA08 FA06 4K001 AA10 BA14 CA23 DA01 EA03 FA14 GA06 GA10 HA01 4K002 AD02 AF10

Claims (8)

[Claims] 1. A method for measuring a metallization ratio of reduced iron comprising iron oxide and metallic iron as a main component and other unavoidable impurities, wherein said reduced iron is charged into a cylinder, and the charged reduced iron is charged from outside the cylinder. A method for rapidly measuring the metallization ratio of reduced iron, comprising calculating a metallization ratio of reduced iron from a current value when excited to a constant voltage by a coil and the weight of the reduced iron charged. 2. The method according to claim 1, wherein a correction is made to the metallization ratio calculated from the current value and the weight of the charged reduced iron according to the temperature of the reduced iron. 3. The method according to claim 1, wherein the dust generated in the steel mill is made of carbonaceous material and is agglomerated by the use of dust pellets reduced by a high-temperature heating furnace. 4. An apparatus for measuring a metallization rate of reduced iron comprising iron oxide, metallic iron as a main component and other unavoidable impurities, comprising: a reduced iron weight measuring unit; and a cylinder filled with the reduced iron. A coil capable of exciting the reduced iron is provided on the outer periphery of the cylinder, and a power supply for exciting the coil is provided.
Metallization of reduced iron, comprising: a measurement unit for measuring the voltage and current of the excited coil; and a calculation unit for calculating a metallization ratio based on the weight of the reduced iron and the measured current value. Quick rate measurement device. 5. A temperature measuring unit for measuring the temperature of reduced iron, and a calculating unit for correcting a metallization ratio calculated based on the weight and current value of the reduced iron at the measured temperature is provided. The apparatus according to claim 4, wherein 6. The apparatus according to claim 4, wherein dust generated in the steelworks is made of carbon material and agglomerated by agglomeration, and dust pellets reduced by a high-temperature heating furnace are used. 7. A method in which a dust generated in an ironworks is provided with carbonaceous materials therein and agglomerated, and the reduced dust pellets are charged into a melting furnace in the next step by reducing the dust pellets by a high-temperature heating furnace. The metallization ratio is measured by the apparatus according to any one of claims 4 to 6, and the supply amount of the carbon material and oxygen in the melting furnace, which is the next step, is determined based on the measured metallization ratio. How to use the rapid iron reduction metallization rate measuring device. 8. The apparatus according to claim 4, wherein the reduced dust pellets are reduced by a method in which carbonaceous material is provided inside a dust generated in an ironworks and agglomerated and reduced by a high-temperature heating furnace. A method of using a reduced iron metallization rate rapid measuring device, characterized in that a metallization ratio is measured by a method, and operating conditions of a high-temperature heating furnace are determined based on the measured metallization ratio.