JP2006249507A - Method for evaluating reducibility of sintered ore - Google Patents
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本発明は、高炉の炉内状況を的確に反映可能な焼結鉱の被還元性評価方法に関する。 The present invention relates to a method for evaluating reducibility of sintered ore that can accurately reflect the in-furnace situation of a blast furnace.
従来、高炉においては、その炉頂部から焼結鉱とコークスとを交互に装入し、焼結鉱とコークスとを炉内で交互に積層して、炉内を上昇する高温の還元ガスにより焼結鉱の還元を行い、溶銑を製造している。このとき、生成した溶銑は、溶融して炉底部に滴下し出銑口から炉外へ排出される。
多くの製鉄所では、この高炉操業を安定に行うため、使用する焼結鉱の還元率を予め測定しており、焼結鉱の被還元性の指標としてJIS−RIを使用している(例えば、非特許文献1参照)。
Conventionally, in a blast furnace, sintered ore and coke are alternately charged from the top of the furnace, and the sintered ore and coke are alternately stacked in the furnace, and then burned by the high-temperature reducing gas rising in the furnace. The hot metal is produced by reducing the ore. At this time, the produced hot metal is melted and dropped on the bottom of the furnace, and is discharged out of the furnace through the outlet.
In many steelworks, in order to perform this blast furnace operation stably, the reduction rate of the sintered ore used is measured in advance, and JIS-RI is used as an index of the reducibility of the sintered ore (for example, Non-Patent Document 1).
しかしながら、JIS−RIを使用して焼結鉱の還元率を測定した場合、大きな還元力(全てCOガス又は窒素ガスを含むCOガス)の下で焼結鉱の被還元性が評価されることになる。このため、高炉炉内で生じる焼結鉱の主要構成物である酸化鉄のみならず、カルシウムフェライトまでが鉄に還元される環境下で、焼結鉱の被還元性が評価されることになり、高炉の炉内状況を反映した評価ができない。 However, when the reduction rate of sintered ore is measured using JIS-RI, the reducibility of the sintered ore is evaluated under a large reducing power (all CO gas or CO gas containing nitrogen gas). become. For this reason, the reducibility of sintered ore is evaluated in an environment where not only iron oxide, which is the main component of sintered ore generated in the blast furnace furnace, but also calcium ferrite is reduced to iron. The evaluation that reflects the in-furnace condition of the blast furnace is not possible.
本発明はかかる事情に鑑みてなされたもので、高炉の炉内状況を的確に反映し、従来よりも精度よく焼結鉱の被還元性を評価して高炉操業を安定に行うことが可能な焼結鉱の被還元性評価方法を提供することを目的とする。 The present invention has been made in view of such circumstances, accurately reflects the in-furnace situation of the blast furnace, and can stably perform blast furnace operation by evaluating the reducibility of the sintered ore with higher accuracy than before. It aims at providing the reducibility evaluation method of sintered ore.
前記目的に沿う本発明に係る焼結鉱の被還元性評価方法は、焼結鉱に還元ガスを接触させて、被還元性を評価する方法において、
前記還元ガスのCO2 含有割合及び温度を変数とするカルシウムフェライトの還元平衡線と酸化鉄の還元平衡線とで挟まれ、かつ800℃以上間接還元温度以下の温度範囲で囲まれる領域内で、焼結鉱の還元率を測定する。
In the method for evaluating the reducibility of the sintered ore according to the present invention in accordance with the above object, the reducing ore is brought into contact with the sintered ore and the reducibility is evaluated.
In a region sandwiched between a reduction equilibrium line of calcium ferrite and a reduction equilibrium line of iron oxide with the CO 2 content ratio and temperature of the reducing gas as variables, and surrounded by a temperature range of 800 ° C. or more and an indirect reduction temperature or less, The reduction rate of sinter is measured.
また、本発明に係る焼結鉱の被還元性評価方法において、前記カルシウムフェライトの還元平衡線は(1)式であり、前記酸化鉄の還元平衡線は(2)式であることが好ましい。
T=−50×R+2150・・・(1)
T=−50×R+2500・・・(2)
ここで、Tは還元ガス温度(℃)、Rは還元ガス中のCO2 含有割合(%)である。
In the method for evaluating reducibility of sintered ore according to the present invention, it is preferable that the reduction equilibrium line of the calcium ferrite is formula (1) and the reduction equilibrium line of the iron oxide is formula (2).
T = −50 × R + 2150 (1)
T = −50 × R + 2500 (2)
Here, T is the reducing gas temperature (° C.), and R is the CO 2 content ratio (%) in the reducing gas.
更に、本発明に係る焼結鉱の被還元性評価方法において、前記間接還元温度は1000℃であることが好ましい。 Furthermore, in the method for evaluating reducibility of sintered ore according to the present invention, the indirect reduction temperature is preferably 1000 ° C.
請求項1〜3記載の焼結鉱の被還元性評価方法は、カルシウムフェライトと酸化鉄の各還元平衡線で挟まれ、かつ800℃以上間接還元温度以下の温度範囲で囲まれる領域内で焼結鉱の還元率を測定するので、高炉の炉内状況を的確に反映した条件下で、従来よりも精度よく焼結鉱の被還元性を評価して高炉操業を安定に行うことができる。 The method for evaluating reducibility of sintered ore according to any one of claims 1 to 3, wherein the sintered ore is baked in a region surrounded by a reduction equilibrium line of calcium ferrite and iron oxide and surrounded by a temperature range of 800 ° C. or more and an indirect reduction temperature or less. Since the reduction rate of the ore is measured, the blast furnace operation can be stably performed by evaluating the reducibility of the sintered ore with higher accuracy than before under conditions that accurately reflect the in-furnace condition of the blast furnace.
続いて、添付した図面を参照しつつ、本発明を具体化した実施の形態につき説明し、本発明の理解に供する。
ここで、図1は本発明の一実施の形態に係る焼結鉱の被還元性評価方法の説明図である。
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory diagram of a method for evaluating reducibility of sintered ore according to an embodiment of the present invention.
図1に示すように、本発明の一実施の形態に係る焼結鉱の被還元性評価方法は、従来使用しているJIS−RIの代わりに使用して焼結鉱の還元率を測定するものであり、高炉の炉内状況を的確に反映した条件下で焼結鉱の被還元性を評価する方法である。以下、詳しく説明する。 As shown in FIG. 1, the method for evaluating the reducibility of sintered ore according to an embodiment of the present invention is used in place of the conventionally used JIS-RI to measure the reduction rate of the sintered ore. This is a method for evaluating the reducibility of sintered ore under conditions that accurately reflect the in-furnace condition of the blast furnace. This will be described in detail below.
図1は、還元ガスのCO2 含有割合(%)と温度(℃)との関係を示しており、このCO2 含有割合(以下、ガス量ともいう)を、CO2 /(CO+CO2 )×100で表している。
従来、高炉に使用する焼結鉱の還元率は、JIS−RIで測定されている。このJIS−RIは、COガス(又は窒素ガスを含むCOガス)100%の雰囲気下において、温度を900℃に維持して例えば3時間経過した時点(図1中の点X)の還元率である。
しかし、これは、強還元下での条件であるため、平衡論的には、焼結鉱の主要構成物である酸化鉄及びカルシウムフェライト(CaO・2Fe2 O3 )が鉄まで還元されてしまう。
FIG. 1 shows the relationship between the CO 2 content ratio (%) of the reducing gas and the temperature (° C.). This CO 2 content ratio (hereinafter also referred to as gas amount) is expressed as CO 2 / (CO + CO 2 ) × 100.
Conventionally, the reduction rate of the sintered ore used for a blast furnace is measured by JIS-RI. This JIS-RI is based on a reduction rate at the time when, for example, 3 hours have passed after maintaining the temperature at 900 ° C. in an atmosphere of 100% CO gas (or CO gas containing nitrogen gas) (point X in FIG. 1). is there.
However, since this is a condition under strong reduction, in equilibrium, iron oxide and calcium ferrite (CaO.2Fe 2 O 3 ), which are the main constituents of sintered ore, are reduced to iron. .
一方、通常の高炉操業条件下のガス還元条件は、例えば、1000℃以下において、カルシウムフェライトが鉄まで還元できない。
従って、従来使用しているJIS−RIでは、高炉の炉内状況を的確に反映できないので、焼結鉱の正確な被還元性を評価できない。
そこで、以下の条件下で、焼結鉱に還元ガスを接触させて被還元性を評価する。
On the other hand, gas reduction conditions under normal blast furnace operating conditions are such that, for example, calcium ferrite cannot be reduced to iron at 1000 ° C. or lower.
Therefore, the conventional JIS-RI cannot accurately reflect the in-furnace situation of the blast furnace, and thus cannot accurately evaluate the reducibility of the sintered ore.
Therefore, the reducibility is evaluated by bringing a reducing gas into contact with the sintered ore under the following conditions.
まず、還元ガスのCO2 含有割合は、還元ガスのCO2 含有割合及び温度を変数とするカルシウムフェライトの還元平衡線と酸化鉄(ウスタイト:FeO)の還元平衡線とで挟まれる領域とする。
ここで、カルシウムフェライトの還元平衡線よりも還元ガス中のCO2 含有割合が少ない領域、即ち強還元領域(図1の左側)では、カルシウムフェライトが鉄まで還元され、この還元平衡線よりも還元ガス中のCO2 ガス量が多い領域、即ち弱還元領域(図1の右側)では、カルシウムフェライトが鉄に還元されることなく安定に存在する。一方、酸化鉄の還元平衡線よりも還元ガス中のCO2 ガス量が少ない強還元領域(図1の左側)では、酸化鉄が鉄まで還元され、この還元平衡線よりも還元ガス中のCO2 ガス量が多い弱還元領域(図1の右側)では、酸化鉄が鉄に還元されることなく安定に存在する。
First, the CO 2 content ratio of the reducing gas is a region sandwiched between the reduction equilibrium line of calcium ferrite and the reduction equilibrium line of iron oxide (wustite: FeO) whose variables are the CO 2 content ratio and temperature of the reducing gas.
Here, in a region where the CO 2 content in the reducing gas is lower than that of calcium ferrite, that is, in the strong reduction region (left side of FIG. 1), calcium ferrite is reduced to iron, and is reduced more than this reduction equilibrium line. In a region where the amount of CO 2 gas in the gas is large, that is, a weak reduction region (right side in FIG. 1), calcium ferrite is stably present without being reduced to iron. On the other hand, in the strong reduction region (left side in FIG. 1) in which the amount of CO 2 gas in the reducing gas is smaller than the iron oxide reduction equilibrium line, the iron oxide is reduced to iron, and the CO in the reducing gas is lower than the reduction equilibrium line. 2 In the weak reduction region with a large amount of gas (right side in FIG. 1), iron oxide exists stably without being reduced to iron.
従って、カルシウムフェライトの還元平衡線と酸化鉄の還元平衡線とで挟まれる領域が、酸化鉄が還元されて生成した鉄とカルシウムフェライトとが共存する領域となるので、この領域内のCO2 含有割合になるように測定温度に応じて還元ガスのCO2 含有割合を調整する。ここで、還元ガス中には、必要に応じて窒素ガスを混入させてもよい。
なお、カルシウムフェライトの還元平衡線と酸化鉄の還元平衡線は、そのまま曲線を使用してもよいが、近似した直線を使用してもよい。
Therefore, since the area sandwiched between the reduction equilibrium line calcium ferrite and reducing equilibrium line of iron oxide, a region where the iron and calcium ferrite iron oxide generated is reduced coexist, CO 2 contained in this area The CO 2 content ratio of the reducing gas is adjusted according to the measurement temperature so as to be a ratio. Here, nitrogen gas may be mixed in the reducing gas as necessary.
Note that, as the reduction equilibrium line of calcium ferrite and the reduction equilibrium line of iron oxide, curves may be used as they are, but approximate straight lines may be used.
近似したカルシウムフェライトの還元平衡線L1は(1)式であり、酸化鉄の還元平衡線L2は(2)式である。
T=−50×R+2150・・・(1)
T=−50×R+2500・・・(2)
ここで、Tは還元ガス温度(℃)、Rは還元ガス中のCO2 含有割合(%)である。
この近似式は、各還元平衡線の両側の点、即ち間接還元温度との交点及び800℃との交点の2点を使用して求めているが、カルシウムフェライト及び酸化鉄の還元平衡線上の各点を最小二乗法を用いて求めることも可能である。
これにより、前記した曲線であるカルシウムフェライト及び酸化鉄の各還元平衡線を使用する場合よりも、被還元性を評価する条件設定が容易になる。
The approximated reduction equilibrium line L1 of calcium ferrite is Equation (1), and the reduction equilibrium line L2 of iron oxide is Equation (2).
T = −50 × R + 2150 (1)
T = −50 × R + 2500 (2)
Here, T is the reducing gas temperature (° C.), and R is the CO 2 content ratio (%) in the reducing gas.
This approximate expression is obtained by using two points on both sides of each reduction equilibrium line, that is, an intersection with the indirect reduction temperature and an intersection with 800 ° C. It is also possible to obtain the points using the least square method.
Thereby, it becomes easier to set conditions for evaluating the reducibility than using the respective reduction equilibrium lines of calcium ferrite and iron oxide, which are the aforementioned curves.
また、焼結鉱の被還元性を評価する温度範囲は、800℃以上間接還元温度以下の温度範囲とする。
温度の下限値を800℃としたのは、800℃未満では反応速度が遅くなり、作業性が悪いためである。一方、上限値を間接還元温度としたのは、間接還元温度を超えると焼結鉱が溶融し始め、高炉の炉内状況を反映できなくなるからである。
従って、間接還元温度は、焼結鉱の直接還元が始まらない温度で、しかも高炉の炉内状況を的確に反映できる温度、即ち1000℃とすることが好ましい。
Moreover, the temperature range which evaluates the reducibility of sintered ore shall be a temperature range of 800 degreeC or more and indirect reduction temperature or less.
The reason why the lower limit value of the temperature is set to 800 ° C. is that when the temperature is less than 800 ° C., the reaction rate becomes slow and workability is poor. On the other hand, the reason why the upper limit value is set as the indirect reduction temperature is that when the indirect reduction temperature is exceeded, the sintered ore starts to melt and the in-furnace state of the blast furnace cannot be reflected.
Therefore, the indirect reduction temperature is preferably set to a temperature at which direct reduction of the sintered ore does not start and a temperature that can accurately reflect the in-furnace condition of the blast furnace, that is, 1000 ° C.
以上の条件下、即ちカルシウムフェライトの還元平衡線と酸化鉄の還元平衡線とで挟まれ、かつ800℃以上間接還元温度以下の温度範囲で囲まれる領域Y(図1中の網かけ部分)内で、焼結鉱の還元率を測定する。ここで、還元率は、例えば、還元ガスのCO2 含有割合及び温度の条件によって変わるため、その条件に応じて、焼結鉱の還元開始から例えば、1時間以上5時間以下の範囲内で測定する。
なお、測定に使用する装置としては、従来JIS−RIの測定を行っている従来公知の還元試験装置(JIS M 8713)を使用するが、他の装置を使用することも勿論可能である。
このようにして求めた焼結鉱の還元率に基づき、高炉の操業条件、例えば、焼結鉱及びコークスの装入速度、高炉の炉内温度、及び羽口からの熱風吹込み量を決定し、高炉を安定に操業することで、溶銑の生産性を従来よりも高めることができる。
Under the above conditions, that is, in a region Y (shaded portion in FIG. 1) sandwiched between a reduction equilibrium line of calcium ferrite and a reduction equilibrium line of iron oxide and surrounded by a temperature range of 800 ° C. or more and an indirect reduction temperature or less. Then, the reduction rate of the sintered ore is measured. Here, since the reduction rate varies depending on, for example, the CO 2 content ratio of the reducing gas and the temperature, it is measured within a range of, for example, 1 hour to 5 hours from the start of the reduction of the sintered ore depending on the conditions. To do.
In addition, as a device used for the measurement, a conventionally known reduction test device (JIS M 8713) that has conventionally performed the measurement of JIS-RI is used, but it is of course possible to use other devices.
Based on the reduction rate of the sinter thus obtained, the operating conditions of the blast furnace, for example, the charging speed of the sinter and coke, the furnace temperature of the blast furnace, and the amount of hot air blown from the tuyere are determined. By operating the blast furnace stably, the productivity of hot metal can be increased more than before.
次に、本発明の作用効果を確認するために行った実施例について説明する。ここで、図2(A)は本発明の実施例に係る焼結鉱の被還元性評価方法を使用した焼結鉱の還元率と高炉での実際の還元率との関係、(B)は従来使用しているJIS−RIを使用した焼結鉱の還元率と高炉での実際の還元率との関係を示す説明図である。なお、本実施例については、従来例と同様に、測定温度を前記した800℃以上間接還元温度以下の範囲内の900℃としている。 Next, examples carried out for confirming the effects of the present invention will be described. Here, FIG. 2 (A) is the relationship between the reduction rate of sintered ore using the method for evaluating reducibility of sintered ore according to the embodiment of the present invention and the actual reduction rate in a blast furnace, and (B) is It is explanatory drawing which shows the relationship between the reduction rate of the sintered ore using JIS-RI used conventionally, and the actual reduction rate in a blast furnace. In addition, about a present Example, the measurement temperature shall be 900 degreeC in the range of above-mentioned 800 degreeC or more and indirect reduction temperature similarly to a prior art example.
図2(A)に示すように、実施例に係る焼結鉱の被還元性評価方法を使用した焼結鉱の還元率、即ちCO2 を含んだ還元力の弱いガスを使用した焼結鉱の還元率は、高炉内における間接還元率との相関性が高く、かつ正相関となっている。なお、ここでは、還元率の相関性が確認できればよいため、本実施例を使用した焼結鉱の還元率については示していないが、例えば、20%以上40%以下の範囲内である。
一方、図2(B)に示すように、従来例に係る焼結鉱の被還元性評価方法(JIS−RI)を使用した焼結鉱の還元率、即ちCO2 を含まない還元力の強いガスを使用した焼結鉱のJIS−RIは、高炉内における間接還元率との相関性が低く、しかも逆相関になっている。
以上のことから、高炉炉内での焼結鉱の被還元性を表す指標として、本発明に係る焼結鉱の被還元性評価方法を使用し、高炉操業を行うことが適切であることが分かる。
As shown in FIG. 2 (A), the reduction rate of sintered ore using the method for evaluating reducibility of sintered ore according to the embodiment, that is, the sintered ore using a gas having low reducing power including CO 2. The reduction rate is highly correlated with the indirect reduction rate in the blast furnace and is positively correlated. Here, since it is only necessary to confirm the correlation of the reduction rate, the reduction rate of the sintered ore using the present embodiment is not shown, but it is, for example, in the range of 20% to 40%.
On the other hand, as shown in FIG. 2B, the reduction rate of sintered ore using the conventional method for evaluating reducibility of sintered ore (JIS-RI), that is, a strong reducing power that does not contain CO 2. The JIS-RI of sintered ore using gas has a low correlation with the indirect reduction rate in the blast furnace, and has an inverse correlation.
From the above, as an index representing the reducibility of sintered ore in a blast furnace, it is appropriate to use the sinter ore reducibility evaluation method according to the present invention and perform blast furnace operation. I understand.
以上、本発明を、実施の形態を参照して説明してきたが、本発明は何ら上記した実施の形態に記載の構成に限定されるものではなく、特許請求の範囲に記載されている事項の範囲内で考えられるその他の実施の形態や変形例も含むものである。例えば、前記したそれぞれの実施の形態や変形例の一部又は全部を組合せて本発明の焼結鉱の被還元性評価方法を構成する場合も本発明の権利範囲に含まれる。 As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above-described embodiment, and the matters described in the claims are not limited. Other embodiments and modifications conceivable within the scope are also included. For example, the case where the method for evaluating reducibility of sintered ore according to the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
Claims (3)
前記還元ガスのCO2 含有割合及び温度を変数とするカルシウムフェライトの還元平衡線と酸化鉄の還元平衡線とで挟まれ、かつ800℃以上間接還元温度以下の温度範囲で囲まれる領域内で、焼結鉱の還元率を測定することを特徴とする焼結鉱の被還元性評価方法。 In the method of contacting the sinter with reducing gas and evaluating the reducibility,
In a region sandwiched between a reduction equilibrium line of calcium ferrite and a reduction equilibrium line of iron oxide with the CO 2 content ratio and temperature of the reducing gas as variables, and surrounded by a temperature range of 800 ° C. or more and an indirect reduction temperature or less, A method for evaluating reducibility of a sintered ore, characterized by measuring a reduction rate of the sintered ore.
T=−50×R+2150・・・(1)
T=−50×R+2500・・・(2)
ここで、Tは還元ガス温度(℃)、Rは還元ガス中のCO2 含有割合(%)である。 2. The method for evaluating reducibility of sintered ore according to claim 1, wherein the reduction equilibrium line of the calcium ferrite is the formula (1), and the reduction equilibrium line of the iron oxide is the formula (2). Method for evaluating reducibility of sintered ore.
T = −50 × R + 2150 (1)
T = −50 × R + 2500 (2)
Here, T is the reducing gas temperature (° C.), and R is the CO 2 content ratio (%) in the reducing gas.
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Cited By (2)
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JP2010174335A (en) * | 2009-01-29 | 2010-08-12 | Jfe Steel Corp | Method for evaluating low-temperature reduction disintegration of sintered ore |
WO2019132280A1 (en) * | 2017-12-26 | 2019-07-04 | 주식회사 포스코 | Device for measuring reduction rate of nickel ore |
Citations (1)
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JPH02236210A (en) * | 1989-03-08 | 1990-09-19 | Nippon Steel Corp | Method for operating blast furnace |
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JPH02236210A (en) * | 1989-03-08 | 1990-09-19 | Nippon Steel Corp | Method for operating blast furnace |
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JPN6009067898, 村山武昭、前田敬之、小野陽一, "焼結鉱の被還元性とその評価", 材料とプロセス, 19920903, Vol.5,No.4, 1058−1061, 社団法人 日本鉄鋼協会 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2010174335A (en) * | 2009-01-29 | 2010-08-12 | Jfe Steel Corp | Method for evaluating low-temperature reduction disintegration of sintered ore |
WO2019132280A1 (en) * | 2017-12-26 | 2019-07-04 | 주식회사 포스코 | Device for measuring reduction rate of nickel ore |
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