TWI576437B - Method for preliminary treatment of molten iron - Google Patents

Method for preliminary treatment of molten iron Download PDF

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TWI576437B
TWI576437B TW103102467A TW103102467A TWI576437B TW I576437 B TWI576437 B TW I576437B TW 103102467 A TW103102467 A TW 103102467A TW 103102467 A TW103102467 A TW 103102467A TW I576437 B TWI576437 B TW I576437B
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slag
furnace
molten iron
treatment
height
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TW103102467A
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TW201437377A (en
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小笠原泰志
内田祐一
三木祐司
伊藤友彦
手塚浩一
田中高太郎
根岸秀光
川畑涼
山本和人
奥山悟郎
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杰富意鋼鐵股份有限公司
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/35—Blowing from above and through the bath
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/04—Removing impurities other than carbon, phosphorus or sulfur
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Description

熔鐵的預備處理方法 Preparation method of molten iron

本發明是有關於一種使用一個轉爐型精煉爐，將熔鐵的脫矽處理與脫磷處理隔著中途的除渣步驟而連續地進行的熔鐵的預備處理方法。 The present invention relates to a method for preparing a molten iron which is continuously performed by a desulfurization treatment and a dephosphorization treatment in a converter type refining furnace.

近年來，正在開發使用了轉爐型精煉爐的熔鐵的預備處理技術，並開發出以下的預備處理方法。亦即，開發出如下的精煉方法(將該精煉方法稱作「2次除渣法」)：在對轉爐型精煉爐內的熔鐵進行脫矽處理後使轉爐型精煉爐傾斜而將爐內的熔渣(將脫矽處理中生成的熔渣(slag)稱作「脫矽熔渣」)的至少一部分排出，然後，向爐內投入CaO系溶劑，對殘留的熔鐵進行脫磷處理(例如參照專利文獻1)。 In recent years, a preparatory treatment technique using a molten iron of a converter type refining furnace has been developed, and the following preliminary treatment methods have been developed. In other words, the following refining method has been developed (this refining method is referred to as "second slag removing method"): after the molten iron in the converter type refining furnace is subjected to deodorization treatment, the converter type refining furnace is tilted and the inside of the furnace is placed At least a part of the molten slag (referred to as "slag slag" generated in the untwisting process) is discharged, and then a CaO-based solvent is introduced into the furnace to dephosphorize the remaining molten iron ( For example, refer to Patent Document 1).

該2次除渣法與轉爐型精煉爐的現有的預備處理方法，即，在精煉開始時投入CaO系溶劑而對轉爐型精煉爐內的熔鐵進行脫矽、脫磷處理的預備處理方法相比，具有以下的優點。亦即，具有如下優點：(1)因在中途將脫矽熔渣排出故可進行矽含量高的熔鐵的處理，可將熔鐵中的矽有效用作熱源，(2)藉由在中途 將脫矽熔渣排出，而可削減其後的脫磷處理時的CaO系溶劑的使用量。 The conventional slag removal method and the conventional preliminary treatment method of the converter type refining furnace, that is, a preliminary treatment method for deactivating and dephosphorizing the molten iron in the converter type refining furnace by introducing a CaO-based solvent at the start of refining Compared, it has the following advantages. That is, it has the following advantages: (1) Since the slag is discharged in the middle, the molten iron having a high cerium content can be treated, the cerium in the molten iron can be effectively used as a heat source, and (2) by midway The desulfurization slag is discharged, and the amount of the CaO-based solvent used in the subsequent dephosphorization treatment can be reduced.

在該2次除渣法中，在脫矽處理後的除渣步驟中，如何迅速地在短時間內將作為目標的規定量的脫矽熔渣自爐內排出，則成為操作上的重要的方面。在除渣步驟中的脫矽熔渣的排出量少的情況下，無法獲得上述的效果，從而與上述現有的轉爐型精煉爐的預備處理方法相同。 In the secondary slag removal method, how quickly the predetermined amount of the slag slag to be discharged from the furnace is quickly discharged in the slag removal step after the devolatilization treatment, which is important in operation. aspect. When the discharge amount of the slag slag in the slag removal step is small, the above-described effects cannot be obtained, and it is the same as the preliminary treatment method of the above-described conventional converter type refining furnace.

而且，亦開發出如下的精煉方法：在脫磷處理結束後，雖經脫磷處理的熔鐵自爐中流出，但使脫磷處理中生成的熔渣(將脫磷處理中生成的熔渣稱作「脫磷熔渣」)殘留於爐內，並向殘留有脫磷熔渣的轉爐型精煉爐中裝入下一次加料(charge)的熔鐵，且對該熔鐵按照上述順序進行預備處理(例如參照專利文獻1及專利文獻2)。該精煉方法進而具有以下的優點。亦即，(3)藉由將脫磷處理中生成的脫磷熔渣殘留於爐內，而可削減脫矽處理時的CaO系溶劑、有效利用脫磷熔渣的顯熱、及回收脫磷熔渣中的鐵成分，(4)藉由重新使用脫磷熔渣及將熔鐵中的矽有效用作熱源而熱效率高，且可提高冷鐵源的調配比率，(5)抑制鹼度((質量%CaO)/(質量%SiO2))相對較高且需要進行時效處理(aging treatment)的脫磷熔渣的產生，可將脫磷熔渣轉換成即便省略時效處理亦可獲得良好的體積穩定性的脫矽熔渣。 Further, a refining method has been developed in which, after the dephosphorization treatment is completed, the molten iron which has been dephosphorized is discharged from the furnace, but the slag generated in the dephosphorization treatment (the slag generated in the dephosphorization treatment) The so-called "dephosphorization slag" remains in the furnace, and the molten iron of the next charge is charged into the converter type refining furnace in which the dephosphorization slag remains, and the molten iron is prepared in the above-described order. Processing (for example, refer to Patent Document 1 and Patent Document 2). This refining method further has the following advantages. In other words, (3) by reducing the dephosphorization slag generated in the dephosphorization treatment in the furnace, the CaO solvent during the deodorization treatment, the sensible heat of the dephosphorization slag can be effectively utilized, and the dephosphorization can be recovered. The iron component in the slag, (4) the thermal efficiency is high by reusing the dephosphorization slag and effectively using the bismuth in the molten iron as a heat source, and the mixing ratio of the cold iron source can be improved, and (5) the alkalinity is suppressed ( (mass % CaO) / (mass % SiO 2 )) The generation of dephosphorization slag which is relatively high and requires aging treatment, and the dephosphorization slag can be converted into a good one even if the aging treatment is omitted. Volume stability of the slag slag.

然而，使脫磷熔渣殘留的方法中，若脫矽處理後的熔渣的排出量不充分，則來源於上一次加料中所殘留的脫磷熔渣的磷 會大量地殘留於爐內，從而在下一次脫磷處理中難以使熔鐵的磷濃度降低至目標水準，因而需要充分確保脫矽處理後的除渣步驟的熔渣的排出量。另一方面，若為了確保熔渣的排出量，而用於除渣的作業時間延長，則可實施此種預備處理的加料數受到限制，而且，若為了增加熔渣的排出速度而使爐體的傾斜角度過於增大，則會引起隨熔渣一併流出的熔鐵的流出量增大而鐵的良率(yield rate)降低這樣的問題。因此，為了不會引起該些問題，需要在脫矽處理後的除渣步驟中效率佳地進行熔渣的排出。 However, in the method of leaving the dephosphorization slag, if the discharge amount of the slag after the deodorization treatment is insufficient, the phosphorus derived from the dephosphorization slag remaining in the last addition is used. A large amount remains in the furnace, so that it is difficult to lower the phosphorus concentration of the molten iron to the target level in the next dephosphorization treatment, and it is necessary to sufficiently ensure the discharge amount of the slag in the slag removal step after the deodorization treatment. On the other hand, if the working time for removing the slag is prolonged in order to secure the discharge amount of the slag, the number of feeds that can be subjected to such preliminary treatment is limited, and the furnace body is made to increase the discharge speed of the slag. If the inclination angle is too large, the problem that the outflow amount of the molten iron flowing out together with the slag increases and the yield of iron decreases is caused. Therefore, in order not to cause such problems, it is necessary to efficiently discharge the slag in the slag removal step after the deodorization treatment.

而且，包含脫矽熔渣或脫磷熔渣在內，製鋼熔渣含有大量的鐵氧化物，因此具有與天然石砂材或高爐熔渣等相比而密度高的傾向。因此，製鋼熔渣無法用於擔心製鋼熔渣會助長重力的不穩定性這樣的土木工程用途中。進而，製鋼熔渣的每單位質量的體積與天然石砂材等相比而較小，因而輸送費用增大亦成為其作為土木工程用材料時的缺點，因此，為了將製鋼熔渣作為容易用於範圍廣的土木工程用途的材料，理想的是減少製鋼熔渣的體積比重。 Further, since the steel slag contains a large amount of iron oxide including the desulfurization slag or the dephosphorization slag, the steel slag tends to have a higher density than natural stone slag or blast furnace slag. Therefore, steel slag cannot be used in civil engineering applications where steel slag contributes to the instability of gravity. Further, since the volume per unit mass of the steel slag is smaller than that of the natural stone sand material or the like, the increase in the transportation cost also becomes a disadvantage when it is used as a material for civil engineering, and therefore, in order to make the steel slag easy to use A wide range of materials for civil engineering purposes, ideally to reduce the bulk specific gravity of steel slag.

因此，本發明者等人對脫矽處理後的除渣步驟的脫矽熔渣的排出性進行了研究。結果可知，若脫矽處理中的脫矽熔渣的起泡(foaming)少，則脫矽熔渣的流動性低，從而難以在規定時間內排出充分量的脫矽熔渣。因此發現，為了在除渣步驟中迅速地使充分量的脫矽熔渣自爐內流出，而必須在脫矽吹煉中使脫矽熔渣穩定地起泡。此處，熔渣的起泡為熔融狀態的熔渣含有氣泡， 而表觀上體積膨脹的現象。 Therefore, the inventors of the present invention have studied the discharge property of the slag slag in the slag removal step after the mash removal treatment. As a result, it is understood that if the foaming of the mashing slag during the mashing treatment is small, the fluidity of the mashing slag is low, and it is difficult to discharge a sufficient amount of mashing slag within a predetermined time. Therefore, it has been found that in order to rapidly discharge a sufficient amount of the degreasing slag from the furnace in the slag removing step, it is necessary to stably foam the slag slag during the smashing and blowing. Here, the slag in which the slag is foamed is in a molten state, and contains bubbles. And apparently the phenomenon of volume expansion.

即，發現重要的是檢測脫矽處理中的熔渣位高(slag level)，並控制脫矽熔渣的起泡。然而，脫矽熔渣的過剩的起泡會在除渣步驟時導致突沸的熔渣流出，從而需要進行抑制該流出的處理，反而會延長除渣步驟的時間，因此亦發現重要的是適度地控制起泡。該些發現並未被記載於專利文獻1及專利文獻2中。 That is, it was found to be important to detect the slag level in the dislocation treatment and control the blistering of the dislocation slag. However, the excessive foaming of the slag slag causes the slag to flow out during the slag removal step, so that the treatment for suppressing the effluent needs to be performed, and the time of the slag removal step is prolonged, so that it is also found that it is important to moderately Control foaming. These findings are not described in Patent Document 1 and Patent Document 2.

先前，作為檢測轉爐型精煉爐中的熔渣的起泡的方法，在專利文獻3中提出有如下方法：在對副噴槍(sublance)賦予固定振動數、振幅的振動(強制振動)的同時一邊測定副噴槍的振動，一邊將副噴槍***至爐內，根據所賦予的強制振動的衰減量，來檢測爐內熔渣的起泡高度。然而，該方法為以副噴槍的前端埋浸在起泡的熔渣的狀態為前提的技術，在起泡少、副噴槍的前端未埋浸在起泡的熔渣的情況下，則無法檢測起泡高度。而且，強制振動的衰減量會根據生成的熔渣的組成或溫度而發生變化，因而難以高精度地檢測起泡高度。 In the prior art, as a method of detecting the blistering of the slag in the converter type refining furnace, Patent Document 3 proposes a method in which a vibration (forced vibration) of a fixed vibration number and an amplitude is applied to a sublance. When the vibration of the sub-lance is measured, the sub-lance is inserted into the furnace, and the foaming height of the slag in the furnace is detected based on the amount of attenuation of the forced vibration applied. However, this method is based on the premise that the tip end of the sub-lance is immersed in the foamed slag. When the foaming is small and the tip of the sub-lance is not immersed in the foamed slag, it cannot be detected. Foaming height. Further, the amount of attenuation of the forced vibration changes depending on the composition or temperature of the generated slag, so that it is difficult to detect the foaming height with high precision.

而且，專利文獻4及專利文獻5中，提出使用微波來測定精煉中的熔渣高度的方法。然而，該些技術為轉爐中的熔鐵的脫碳精煉的起泡檢測技術，因熔鐵預備處理的脫矽處理中的脫矽熔渣與轉爐的脫碳精煉中的轉爐熔渣在熔渣的溫度、鹼度、氧化鐵濃度方面大不相同，故導電率大不相同，因此，微波的反射特性在脫矽處理與脫碳精煉中相異，從而無法將脫碳精煉中的實際成果直接應用於脫矽處理中。 Further, Patent Document 4 and Patent Document 5 propose a method of measuring the slag height in refining using microwaves. However, these techniques are a foaming detection technique for decarburization refining of molten iron in a converter, and the desulfurization slag in the decarburization treatment of the molten iron preparation treatment and the converter slag in the decarburization refining of the converter are in the slag The temperature, alkalinity, and iron oxide concentration are very different, so the electrical conductivity is very different. Therefore, the microwave reflection characteristics are different in the decarburization treatment and the decarburization refining, so that the actual results in the decarburization refining cannot be directly Used in dislocation treatment.

例如，專利文獻4中記載了如下內容：其原理雖不明，但基於發送波與反射波的混合波的頻率變化來檢測熔渣位高，或根據微波的反射率來檢測熔渣位高。然而，導電率小的脫矽熔渣中，微波的反射率非常小而大部分穿透，因此亦存在來自熔鐵浴面的反射波或熔鐵浴面與熔渣表面的多重反射波，因而專利文獻4的方法中無法檢測熔渣位高。 For example, Patent Document 4 describes that the principle is not known, but the slag level is detected based on the frequency change of the mixed wave of the transmitted wave and the reflected wave, or the slag level is detected based on the reflectance of the microwave. However, in the untwisted slag having a small electrical conductivity, the reflectance of the microwave is very small and most of the penetration, so there are also reflected waves from the molten iron bath surface or multiple reflected waves from the molten iron bath surface and the slag surface. In the method of Patent Document 4, the slag level cannot be detected.

而且，專利文獻5中，將發送接收用的天線***至爐內，在暴露於高溫的熔渣或熔鐵的液滴的精煉爐內，即便於短時間內使用，該些液滴亦會附著於天線而凝固，因此難以在精煉期間內連續地進行測定。 Further, in Patent Document 5, an antenna for transmission and reception is inserted into a furnace, and in a refining furnace exposed to high-temperature slag or molten iron droplets, the droplets adhere to each other even when used for a short period of time. It solidifies on the antenna, so it is difficult to perform measurement continuously during the refining period.

先前技術文獻 Prior technical literature

專利文獻 Patent literature

專利文獻1：日本專利特開平11-323420號公報 Patent Document 1: Japanese Patent Laid-Open No. Hei 11-323420

專利文獻2：日本專利特開2001-271113號公報 Patent Document 2: Japanese Patent Laid-Open Publication No. 2001-271113

專利文獻3：日本專利特開平5-255726號公報 Patent Document 3: Japanese Patent Laid-Open No. Hei 5-255726

專利文獻4：日本專利特開昭59-41409號公報 Patent Document 4: Japanese Patent Laid-Open No. 59-41409

專利文獻5：日本專利特開平3-281717號公報 Patent Document 5: Japanese Patent Laid-Open No. Hei 3-281717

本發明鑒於上述情況而完成，其目的在於提供一種熔鐵的預備處理方法，該方法使用一個轉爐型精煉爐將熔鐵的脫矽處理與脫磷處理隔著中途的除渣步驟而連續地進行，在脫矽處理後的除渣步驟中抑制突沸的熔渣的流出，並可將作為目標的規定量 的脫矽熔渣迅速地在短時間內排出至爐外，在下一步驟的脫磷處理中，可進行對於成本方面及品質方面而言充分的脫磷處理。而且，提供一種可獲得適合於各種土木工程用材料的體積比重相對較小的熔渣的熔鐵的預備處理方法。 The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for preparing a molten iron which is continuously carried out by using a converter type refining furnace to separate a molten iron from a degreasing treatment and a dephosphorization treatment. In the slag removal step after the deodorization treatment, the outflow of the slag from the slag is suppressed, and the specified amount as the target can be The desulfurization slag is quickly discharged to the outside of the furnace in a short time, and in the dephosphorization treatment in the next step, dephosphorization treatment sufficient in terms of cost and quality can be performed. Further, there is provided a preliminary treatment method for obtaining molten iron which is suitable for various slags having a relatively small specific gravity in materials for civil engineering.

用以解決上述課題的本發明的主旨為以下所示。 The gist of the present invention for solving the above problems is as follows.

[1]一種熔鐵的預備處理方法，包括：脫矽處理步驟，自頂吹式噴槍對轉爐型精煉爐內的熔鐵供給氣態氧源而對熔鐵進行脫矽處理；除渣步驟，將該脫矽處理步驟中生成的熔渣的至少一部分自上述轉爐型精煉爐排出；以及脫磷處理步驟，在該除渣步驟後，向上述轉爐型精煉爐內添加CaO系溶劑，自上述頂吹式噴槍供給氣態氧源而對殘留的熔鐵進行脫磷處理，上述熔鐵的預備處理方法的特徵在於：在上述脫矽處理中對爐內的熔渣高度進行測定，在測定出的熔渣高度相對於自爐內的熔鐵浴面至爐口為止的爐內自由區域的高度的比率為規定的範圍的狀態下，結束脫矽處理。 [1] A method for preparing a molten iron, comprising: a dislocation treatment step of supplying a molten oxygen source to a molten oxygen source in a converter type refining furnace from a top-blowing type spray gun to perform a deodorization treatment on the molten iron; At least a part of the slag generated in the deodorization treatment step is discharged from the converter type refining furnace; and a dephosphorization treatment step, after the slag removal step, a CaO solvent is added to the converter type refining furnace, and the top blowing is performed from the top blowing The lance is supplied with a gaseous oxygen source to dephosphorize the residual molten iron, and the molten iron preparation method is characterized in that the slag height in the furnace is measured during the detachment treatment, and the slag is measured. The dislocation process is terminated in a state where the ratio of the height to the height of the free area in the furnace from the molten iron bath surface in the furnace to the furnace opening is within a predetermined range.

[2]如上述[1]所述的熔鐵的預備處理方法，其特徵在於：上述比率的規定的範圍為0.5~0.9的範圍。 [2] The method for preparing a molten iron according to [1] above, wherein the predetermined range of the ratio is in a range of 0.5 to 0.9.

[3]如上述[1]或上述[2]所述的熔鐵的預備處理方法，其特徵在於：根據上述熔渣高度的測定結果，在上述脫矽處理中，對選自來自頂吹式噴槍的氣態氧源的供給流量、頂吹式噴槍的噴槍高度、來自底吹風口的攪拌用氣體的供給流量、爐內的熔渣的組成、起泡鎮靜材料(foaming killing material)的投入量所組成的群組中的至少1種進行調整，藉由該調整對脫矽處理中的爐內的熔渣 高度進行控制。 [3] The method for preparing a molten iron according to the above [1] or [2], wherein, in the dislocation treatment, the pair is selected from the top blowing type according to the measurement result of the slag height. The supply flow rate of the gaseous oxygen source of the spray gun, the height of the spray gun of the top-blowing spray gun, the supply flow rate of the stirring gas from the bottom air outlet, the composition of the molten slag in the furnace, and the input amount of the foaming killing material At least one of the group consisting of adjustments, by adjusting the slag in the furnace in the deodorization process Height control.

[4]如上述[3]所述的熔鐵的預備處理方法，其特徵在於：以上述脫矽處理中的上述熔渣高度相對於爐內自由區域的高度的比率為0.5~0.9的範圍內的方式，對脫矽處理中的爐內的熔渣高度進行控制。 [4] The method for preparing a molten iron according to the above [3], wherein a ratio of the slag height to a height of a free area in the furnace in the detachment treatment is in a range of 0.5 to 0.9. The way to control the slag height in the furnace during the dislocation process.

[5]如上述[1]至上述[4]中任一項所述的熔鐵的預備處理方法，其特徵在於：使用擬似隨機信號處理雷達方式微波距離計，將10GHz以下的頻率的微波發送至上述轉爐型精煉爐內並接收反射波，根據反射波的往返傳播時間而求出直至對象物為止的距離，在接收到的某規定的強度以上的反射波的信號中，將直至與反射波的信號相對應的對象物為止的距離大於直至爐口為止的距離且最接近直至爐口為止的距離的反射波的信號判定為來自熔渣表面的反射波的信號，而求出直至熔渣表面為止的距離，根據所求出的直至熔渣表面為止的距離來測定上述熔渣高度。 [5] The method for preparing a molten iron according to any one of [1] to [4] above, characterized in that: using a pseudo-random signal processing radar type microwave distance meter, microwaves of frequencies below 10 GHz are transmitted. In the converter type refining furnace, the reflected wave is received, and the distance to the object is obtained based on the round-trip propagation time of the reflected wave, and the reflected wave of the received reflected wave of a predetermined intensity or more is up to and reflected. The distance from the object corresponding to the signal is larger than the distance from the furnace mouth, and the signal of the reflected wave closest to the distance from the furnace mouth is determined as the signal of the reflected wave from the surface of the slag, and is obtained up to the surface of the slag. The distance to the slag is measured based on the distance from the obtained slag surface.

[6]如上述[5]所述的熔鐵的預備處理方法，其特徵在於：在由上述距離計接收的反射波的信號中，將直至與反射波的信號相對應的對象物為止的距離並未自脫矽處理開始時發生變化而是繼續存在的反射波的信號作為雜訊而加以去除，然後判定來自上述熔渣表面的反射波的信號。 [6] The method for preparing a molten iron according to the above [5], wherein the distance from the object corresponding to the signal of the reflected wave to the signal of the reflected wave received by the distance meter is The signal of the reflected wave that has not changed since the start of the dislocation process is removed as noise, and then the signal of the reflected wave from the surface of the slag is determined.

[7]如上述[1]至上述[4]中任一項所述的熔鐵的預備處理方法，其特徵在於：使用擬似隨機信號處理雷達方式微波距離計，將10GHz以下的頻率的微波發送至上述轉爐型精煉爐內並接收來 自爐內的反射波，根據反射波的往返傳播時間而求出直至對象物為止的距離，在來自存在於爐口至熔鐵浴面為止的範圍內的對象物的反射波的信號中，將直至與反射波的信號相對應的對象物為止的距離並未自脫矽處理開始時發生變化而是繼續存在的反射波的信號作為雜訊而加以去除，然後將與熔鐵浴面相對應的反射波的信號去除而將反射強度最高的反射波的信號判定為來自熔渣表面的反射波的信號，而求出直至熔渣表面為止的距離，根據所求出的直至熔渣表面為止的距離來測定上述熔渣高度。 [7] The method for preparing a molten iron according to any one of the above [1] to [4] characterized in that, by using a pseudo-random signal processing radar type microwave distance meter, microwaves of frequencies below 10 GHz are transmitted. To the above converter type refining furnace and receive it The reflected wave from the furnace is obtained from the round-trip propagation time of the reflected wave, and the distance from the object to the reflected wave is reflected in the signal from the object in the range from the furnace opening to the molten iron bath surface. The distance until the object corresponding to the signal of the reflected wave does not change from the start of the dislocation process, but the signal of the reflected wave that continues to exist is removed as noise, and then the reflection corresponding to the surface of the molten iron bath is removed. The signal of the wave is removed, and the signal of the reflected wave having the highest reflection intensity is determined as a signal of the reflected wave from the surface of the slag, and the distance up to the surface of the slag is obtained, and the distance up to the surface of the slag is determined based on the obtained distance from the surface of the slag. The above slag height was measured.

[8]如上述[1]至上述[7]中任一項所述的熔鐵的預備處理方法，其特徵在於：在上述轉爐型精煉爐中的上一次加料的熔鐵的脫磷處理步驟結束後，使經脫磷處理的熔鐵流出，在不使脫磷處理中生成的爐內的熔渣排出而殘留於上述轉爐型精煉爐內的狀態下，將新的熔鐵裝入至上述轉爐型精煉爐內，對該熔鐵實施上述脫矽處理步驟，在該脫矽處理結束時，將爐內熔渣的鹼度設為0.8以上、1.5以下，熔鐵的溫度設為1280℃以上、1380℃以下，熔鐵的矽含量設為0.10質量%以下，在上述除渣步驟中，將脫矽處理步驟中生成的熔渣的30質量%以上排出至爐外，然後，對爐內的熔鐵實施上述脫磷處理步驟，在該脫磷處理步驟結束後，使經脫磷處理的熔鐵流出，在不使脫磷處理中生成的爐內的熔渣排出而殘留於上述轉爐型精煉爐內的狀態下，將新的熔鐵裝入至上述轉爐型精煉爐內，對該熔鐵進行預備處理。 [8] The method for preparing a molten iron according to any one of the above [1], wherein the step of dephosphorization of the molten iron of the last addition in the converter type refining furnace After the completion, the molten iron which has been subjected to the dephosphorization treatment is discharged, and the molten iron in the furnace which is formed in the dephosphorization treatment is discharged and left in the converter type refining furnace, and a new molten iron is charged into the above. In the converter type refining furnace, the molten iron is subjected to the above-described deodorization treatment step, and when the deodorization treatment is completed, the alkalinity of the molten slag in the furnace is set to 0.8 or more and 1.5 or less, and the temperature of the molten iron is set to 1280 ° C or higher. At 1380 ° C or lower, the cerium content of the molten iron is set to 0.10% by mass or less, and in the slag removing step, 30% by mass or more of the slag generated in the mashing step is discharged to the outside of the furnace, and then, in the furnace. The molten iron is subjected to the above-described dephosphorization treatment step, and after the dephosphorization treatment step is completed, the dephosphorization-treated molten iron is discharged, and the molten slag in the furnace which is not generated in the dephosphorization treatment is discharged and remains in the converter type refining. In the state of the furnace, a new molten iron is charged to the above-mentioned converter type refining furnace The molten iron is subjected to preliminary treatment.

[9]如上述[1]至上述[8]中任一項所述的熔鐵的預備處理方 法，其特徵在於：在除渣步驟後的脫磷處理中測定爐內的熔渣高度，對選自來自頂吹式噴槍的氣態氧源的供給流量、頂吹式噴槍的噴槍高度、來自底吹風口的攪拌用氣體的供給流量所組成的群組中的至少1種進行調整，並以藉由該調整而爐內的熔渣不會自爐口噴出的方式進行控制。 [9] The preparation process of the molten iron according to any one of the above [1] to [8] The method is characterized in that the slag height in the furnace is measured in the dephosphorization treatment after the slag removing step, the supply flow rate from the gaseous oxygen source selected from the top-blowing lance, the height of the lance of the top-blowing lance, and the bottom At least one of the group consisting of the supply flow rate of the agitation gas of the air outlet is adjusted, and the slag in the furnace is not discharged from the furnace port by the adjustment.

根據本發明，在使用一個轉爐型精煉爐將熔鐵的脫矽處理與脫磷處理隔著中途的除渣步驟而連續地進行的熔鐵的預備處理中，在脫矽處理結束時，在使已起泡的脫矽熔渣的高度相對於爐內自由區域的高度的比率為規定的範圍的狀態下結束脫矽處理，因而在其後的除渣步驟中，實現如下：抑制脫矽熔渣的突沸流出，並將作為目標的規定量的脫矽熔渣迅速地在短時間內排出至爐外。藉此，除渣步驟不會延遲而可順利地進行，並且在下一步驟的脫磷處理中，能夠以少的CaO系溶劑的使用量將熔鐵的磷濃度降低至低濃度。 According to the present invention, in the preparation process of the molten iron which is continuously performed by the degreasing treatment and the dephosphorization treatment in the middle of the slag removal step by using a single converter type refining furnace, when the disintegration treatment is completed, The deodorization treatment is terminated in a state where the ratio of the height of the foamed slag slag to the height of the free region in the furnace is within a predetermined range, and thus, in the subsequent slag removal step, the following is achieved: suppression of the slag slag The sudden outflow occurs, and the target amount of the desulfurization slag is quickly discharged to the outside of the furnace in a short time. Thereby, the slag removal step can be smoothly performed without delay, and in the dephosphorization treatment in the next step, the phosphorus concentration of the molten iron can be lowered to a low concentration with a small amount of the CaO-based solvent.

1‧‧‧轉爐型精煉爐 1‧‧‧ Converter type refining furnace

2‧‧‧頂吹式噴槍 2‧‧‧Top blow gun

3‧‧‧底吹風口 3‧‧‧ bottom air outlet

4‧‧‧流出口 4‧‧‧Exit

5‧‧‧熔鐵 5‧‧‧ molten iron

6‧‧‧脫矽熔渣 6‧‧‧Disintegration slag

7‧‧‧冷鐵源 7‧‧‧Cold iron source

8‧‧‧氧氣 8‧‧‧Oxygen

9‧‧‧底吹氣體 9‧‧‧ bottom blowing gas

10‧‧‧裝料鍋 10‧‧‧Loading pot

11‧‧‧煙道 11‧‧‧ flue

12‧‧‧罩 12‧‧‧ Cover

13、14‧‧‧開口部 13, 14‧‧‧ openings

15‧‧‧微波熔渣位高計 15‧‧‧Microwave slag level

16‧‧‧波導管 16‧‧‧waveguide

17‧‧‧發送天線 17‧‧‧Transmission antenna

18‧‧‧接收天線 18‧‧‧ receiving antenna

圖1是實施本發明的熔鐵的預備處理方法時所使用的轉爐型精煉爐的概略剖面圖。 Fig. 1 is a schematic cross-sectional view showing a converter type refining furnace used in carrying out a method for preparing a molten iron according to the present invention.

圖2(A)~圖2(E)是按照步驟順序表示本發明的熔鐵的預備處理方法的概略圖。 2(A) to 2(E) are schematic views showing a preliminary processing method of the molten iron of the present invention in order of steps.

圖3是表示使用微波熔渣位高計採取到的反射波的信號的一 例的圖。 Figure 3 is a diagram showing a signal of a reflected wave taken using a microwave slag level gauge Example of the example.

圖4是根據藉由微波熔渣位高計獲得的測定結果而求出脫矽處理中的爐內的熔渣高度的推移的圖。 4 is a view showing the transition of the slag height in the furnace during the untwisting process based on the measurement results obtained by the microwave slag level gauge.

圖5是表示脫矽處理結束時的熔渣高度與中間除渣時間的關係的圖。 Fig. 5 is a view showing the relationship between the slag height at the end of the untwisting treatment and the intermediate slag removal time.

圖6是表示脫矽處理結束時的熔渣高度與脫磷處理結束後的熔鐵中磷濃度的關係的圖。 Fig. 6 is a graph showing the relationship between the slag height at the end of the deodorization treatment and the phosphorus concentration in the molten iron after the dephosphorization treatment is completed.

圖7是表示來自頂吹式噴槍的送氧速度對熔渣高度造成的影響的圖。 Fig. 7 is a view showing the influence of the oxygen supply rate from the top-blowing lance on the slag height.

圖8是表示頂吹式噴槍的噴槍高度對熔渣高度造成的影響的圖。 Fig. 8 is a view showing the influence of the height of the lance of the top-blowing lance on the slag height.

圖9是表示底吹氣體流量對熔渣高度造成的影響的圖。 Fig. 9 is a graph showing the influence of the flow rate of the bottom blowing gas on the slag height.

圖10是表示本發明例1、本發明例2及比較例1、比較例2的脫矽處理中熔渣高度相對於爐內的自由區域的高度的比率的推移的圖。 FIG. 10 is a view showing transition of the ratio of the slag height to the height of the free region in the furnace in the untwisting process of the first embodiment of the present invention, the second embodiment of the present invention, and the comparative example 1 and the comparative example 2.

圖11是表示本發明例3、比較例2的脫磷處理中熔渣高度相對於爐內的自由區域的高度的比率的推移的圖。 Fig. 11 is a graph showing the transition of the ratio of the slag height to the height of the free region in the furnace in the dephosphorization treatment of Examples 3 and 2 of the present invention.

以下，參照隨附圖式對本發明進行具體說明。圖1是實施本發明的熔鐵的預備處理方法時所使用的轉爐型精煉爐的概略剖面圖，圖2(A)~圖2(E)是按步驟順序表示本發明的熔鐵的預備處理方法的步驟的概略圖。另外，圖1是表示圖2(B)的脫 矽處理步驟的圖。 Hereinafter, the present invention will be specifically described with reference to the accompanying drawings. Fig. 1 is a schematic cross-sectional view showing a converter type refining furnace used in the method for preparing a molten iron according to the present invention, and Figs. 2(A) to 2(E) are diagrams showing the preparatory treatment of the molten iron of the present invention in order of steps. A schematic diagram of the steps of the method. In addition, FIG. 1 is a view showing the off of FIG. 2(B). 图 Diagram of the processing steps.

本發明的熔鐵的預備處理方法中，使用圖1所示的可進行頂吹底吹的轉爐型精煉爐1。經由在轉爐型精煉爐1的內部可升降的頂吹式噴槍2，自頂吹式噴槍2的前端將作為氣態氧源的含氧氣體朝向熔鐵5供給而進行頂吹。作為含氧氣體，可使用氧氣、富含氧的空氣、空氣、氧氣與惰性氣體的混合氣體。圖1中，表示使用氧氣8作為含氧氣體的示例。此處，氧氣8為工業用純氧。經由設置在轉爐型精煉爐1的底部的底吹風口3而進行底吹。作為底吹氣體9，可為含氧氣的氣體，或者亦可僅為氬氣或氮氣等惰性氣體。而且，底吹氣體除具有藉由向熔鐵中吹入而強化熔鐵5的攪拌並促進冷鐵源的熔解的功能外，亦可具有自底吹風口3將搬送用氣體連同造渣劑一併吹入至熔鐵中的功能。另外，圖1的詳細說明將於以後進行敘述。 In the method for preparing a molten iron according to the present invention, a converter type refining furnace 1 capable of performing top blowing and bottom blowing as shown in Fig. 1 is used. The top-blowing lance 2 that can be lifted and lowered inside the converter-type refining furnace 1 supplies the oxygen-containing gas as a gaseous oxygen source to the molten iron 5 from the tip end of the top-blowing lance 2 to perform top-blowing. As the oxygen-containing gas, oxygen, oxygen-enriched air, air, a mixed gas of oxygen and an inert gas can be used. In Fig. 1, an example in which oxygen gas 8 is used as an oxygen-containing gas is shown. Here, the oxygen 8 is pure oxygen for industrial use. The bottom blowing is performed via the bottom air outlet 3 provided at the bottom of the converter type refining furnace 1. As the bottom blowing gas 9, it may be an oxygen-containing gas, or may be only an inert gas such as argon or nitrogen. Further, the bottom blowing gas has a function of enhancing the agitation of the molten iron 5 by blowing into the molten iron and promoting the melting of the cold iron source, and may also have a gas for conveying from the bottom air outlet 3 together with the slag forming agent. And blow into the function of the molten iron. In addition, the detailed description of FIG. 1 will be described later.

本發明中，熔鐵5的精煉中使用2台以上的轉爐型精煉爐1，將其中的至少1台轉爐型精煉爐1用於本發明的熔鐵預備處理，將剩下的至少1台用於實施了本發明的熔鐵預備處理的熔鐵5的脫碳精煉。即，在熔鐵預備處理用的轉爐型精煉爐1中進行預備處理，繼而，將實施了預備處理的熔鐵5向脫碳精煉用的轉爐型精煉爐1移位而進行脫碳處理。 In the present invention, two or more converter type refining furnaces 1 are used for the refining of the molten iron 5, and at least one of the converter type refining furnaces 1 is used for the molten iron preparation process of the present invention, and at least one of the remaining ones is used. Decarburization refining of the molten iron 5 in which the molten iron preparation process of the present invention is carried out. In other words, in the converter type refining furnace 1 for the molten iron preparation process, the preliminary treatment is performed, and then the molten iron 5 subjected to the preliminary treatment is displaced to the converter type refining furnace 1 for decarburization refining, and decarburization treatment is performed.

本發明的熔鐵5的預備處理方法中，如圖2(A)所示，在預先裝入了鐵屑等冷鐵源7的轉爐型精煉爐1中，經由裝料鍋10而裝入未實施脫矽處理及脫磷處理的熔鐵5(熔鐵裝入步驟)。 In the preliminary processing method of the molten iron 5 of the present invention, as shown in Fig. 2(A), the converter type refining furnace 1 in which the cold iron source 7 such as iron filings is previously loaded is loaded through the charging pot 10. The molten iron 5 (melting iron charging step) for performing the deodorizing treatment and the dephosphorization treatment.

繼而，向該轉爐型精煉爐內的熔鐵5供給作為氧源的氣態氧源或者氣態氧源及氧化鐵等固體氧源，且如圖2(B)所示實施脫矽處理(脫矽處理步驟)。熔鐵5中所含有的矽與氧源中的氧發生反應(Si+2O→SiO2)而進行脫矽處理。利用由該脫矽反應產生的矽的氧化熱而熔鐵溫度上升，從而促進熔鐵中的冷鐵源7的熔解。 Then, a molten oxygen source as a source of oxygen, a gaseous oxygen source, and a solid oxygen source such as iron oxide are supplied to the molten iron 5 in the converter-type refining furnace, and a dislocation treatment (dislocation treatment) is performed as shown in FIG. 2(B). step). Oxygen in the silicon and oxygen source 5 molten iron contained in the deprotection reaction of silicon treated (Si + 2O → SiO 2) . The melting temperature of the molten iron is increased by the heat of oxidation of the crucible generated by the decoupling reaction, thereby promoting the melting of the cold iron source 7 in the molten iron.

本發明中，使用一個轉爐型精煉爐1實施脫矽處理及脫磷處理，在實施脫矽處理時，上一次加料的脫磷處理中生成的脫磷熔渣附著並殘留於轉爐型精煉爐1的爐壁上。因此，在脫矽處理中，在不對脫矽熔渣6的鹼度((質量%CaO)/(質量%SiO2))(以下，亦有時僅表示為「鹼度」)進行控制的情況下，有發生殘留的脫磷熔渣中所含有的磷氧化物(P2O5)分解而熔鐵5的磷濃度上升即所謂的「複磷」之虞。在為了削減脫矽處理時的CaO系溶劑的使用量，而意圖使脫磷熔渣殘留於爐內的情況下，有複磷引起的磷濃度的上升更大之虞。即，為了防止上述複磷，較佳為對脫矽處理中生成的脫矽熔渣6的鹼度進行調整。 In the present invention, the desulfurization treatment and the dephosphorization treatment are carried out using one converter type refining furnace 1, and the dephosphorization slag generated in the dephosphorization treatment of the last feeding is adhered and remains in the converter type refining furnace 1 when the deodorization treatment is performed. On the wall of the furnace. Therefore, the removal of silicon processing, alkalinity ((mass% CaO) / (mass% SiO 2)) do not slag off the silicon 6 (hereinafter, also only when expressed as "alkalinity") control of the situation Then, the phosphorus oxide (P 2 O 5 ) contained in the dephosphorization slag remaining is decomposed, and the phosphorus concentration of the molten iron 5 rises, that is, the so-called "rephosphorization". When the amount of the CaO-based solvent used in the deodorization treatment is reduced, and the dephosphorization slag is intended to remain in the furnace, the increase in the phosphorus concentration due to the rephosphorization is greater. That is, in order to prevent the above-mentioned rephosphorization, it is preferable to adjust the alkalinity of the degumming slag 6 generated in the deodorization treatment.

在通常的脫矽處理條件下，熔鐵溫度為1300℃左右，且，脫矽熔渣中的FeO濃度為10質量%~20質量%左右，若考慮到該些，則藉由將脫矽處理後的脫矽熔渣6的鹼度設為0.8以上，而複磷反應得到抑制。 Under the usual conditions of the dislocation treatment, the temperature of the molten iron is about 1300 ° C, and the concentration of FeO in the desulfurization slag is about 10% by mass to 20% by mass, and if these are taken into consideration, the dislocation treatment is performed. The alkalinity of the subsequent desulfurization slag 6 is set to 0.8 or more, and the phosphorus recombination reaction is suppressed.

脫矽熔渣6的鹼度((質量%CaO)/(質量%SiO2))可根據下述的(1)式而計算。 The alkalinity ((% by mass CaO) / (% by mass SiO 2 )) of the mashing slag 6 can be calculated according to the following formula (1).

鹼度=[(爐內殘留CaO量(kg/熔鐵-t))+(脫矽處理中的添加CaO量(kg/熔鐵-t))]/[(爐內殘留SiO2量(kg/熔鐵-t))+(脫矽處理中的生成SiO2量(kg/熔鐵-t))]...(1) Alkalinity = [(remaining CaO amount in the furnace (kg / molten iron - t)) + (addition of CaO in the deodorization treatment (kg / molten iron - t))] / [(the amount of residual SiO 2 in the furnace (kg /Fused iron-t))+(The amount of SiO 2 produced in the deuterium treatment (kg/melt-t))]...(1)

另外，爐內殘留CaO量及爐內殘留SiO2量為爐內殘留的上一次加料的脫磷熔渣中所含有的CaO量及SiO2量，脫矽處理中的生成SiO2量可根據脫矽處理前後的熔鐵中的Si濃度的變化而算出。 Further, the furnace and the furnace residual amount of CaO in an amount of SiO 2 remaining on the furnace dephosphorization slag remaining amount of CaO contained in the primary feed and the amount of SiO 2, an amount of generated SiO 2 silicon removal process may vary depending off The change in the Si concentration in the molten iron before and after the enthalpy treatment was calculated.

作為用於脫矽處理的氧源，可僅使用來自頂吹式噴槍2的氧氣8，而且，亦可併用氧氣8與氧化鐵(未圖示)等固體氧源。為了在短時間內進行的脫矽處理中生成目標鹼度的脫矽熔渣6，有效的是使用具有促進CaO系溶劑的渣化的功能的氧化鐵。然而，自作為本發明的目的之一的使大量的冷鐵源7熔解的觀點考慮，大量使用升熱時及分解時吸熱的氧化鐵欠佳，因此，較佳為使氧化鐵的使用量為必要最小限度。而且，因使用轉爐型精煉爐1作為精煉容器，故可增大氧氣供給速度，即便僅使用氧氣8進行脫矽處理，亦可充分促進CaO系溶劑的渣化而生成目標鹼度的脫矽熔渣6。 As the oxygen source for the degassing treatment, only the oxygen gas 8 from the top-blowing lance 2 can be used, and a solid oxygen source such as oxygen 8 and iron oxide (not shown) can be used in combination. In order to generate the target alkalinity desulfurization slag 6 in the decarburization treatment performed in a short time, it is effective to use iron oxide having a function of promoting slag formation of a CaO-based solvent. However, from the viewpoint of melting a large amount of cold iron source 7 as one of the objects of the present invention, it is considered that a large amount of iron oxide which absorbs heat during heating and decomposition is inferior, and therefore, it is preferable to use iron oxide in an amount of The minimum necessary. Further, since the converter type refining furnace 1 is used as the refining vessel, the oxygen supply rate can be increased, and even if only the oxygen gas 8 is used for the deodorization treatment, the slag of the CaO solvent can be sufficiently promoted to generate the target alkalinity desulfurization. Slag 6.

在該脫矽處理步驟之後，如圖2(C)所示，使轉爐型精煉爐3向設置著流出口4一側的相反側傾斜，從而將脫矽處理中產生的含有大量SiO2的脫矽熔渣6經由轉爐型精煉爐1的爐口而排出至配置在下方的軌道上的熔渣罐(slag pot)(未圖示)(除 渣步驟)。使轉爐型精煉爐1在熔鐵5不會自爐口流出的範圍內傾斜，藉由自爐口的溢流而排出脫矽熔渣6，自傾斜的爐體的爐口下端起至熔渣表面為止的高度越高則能夠越有效地排出，但無法將脫矽熔渣6完全排出，脫矽熔渣6的一部分仍會殘留於爐內。脫矽熔渣6的除渣步驟在脫矽處理與脫磷處理之間進行，因而亦稱作「中間除渣」。 After removal of the silicon processing steps shown in FIG 2 (C) shown in the converter type refining furnace 3 is provided with the inclined side opposite to the side stream port 4, thereby de-treated silica containing a large amount of generated SiO 2 removal The slag slag 6 is discharged to a slag pot (not shown) disposed on the lower rail via the furnace opening of the converter type refining furnace 1 (slag removal step). The converter type refining furnace 1 is inclined in a range in which the molten iron 5 does not flow out from the furnace mouth, and the degreasing slag 6 is discharged by overflow from the furnace mouth, from the lower end of the furnace mouth of the inclined furnace body to the slag The higher the height of the surface, the more efficiently it can be discharged, but the untwisting slag 6 cannot be completely discharged, and a part of the slag slag 6 remains in the furnace. The slag removal step of the mashing slag 6 is carried out between the mashing treatment and the dephosphorization treatment, and is therefore also referred to as "intermediate slag removal".

在除渣步驟後，向殘留於轉爐型精煉爐內的熔鐵5供給CaO系溶劑及氧源，如圖2(D)所示，對熔鐵5進行脫磷處理(脫磷處理步驟)。脫磷處理步驟中，爐內的熔渣的鹼度調整為1.3~3.5的範圍。該脫磷處理步驟中使用的氧源與脫矽處理同樣地，以來自頂吹式噴槍2的氧氣8為主體，但亦可部分使用氧化鐵。然而，本發明的目的之一在於熔解大量的冷鐵源7，如上述般，較佳為儘可能地避免將升熱時及分解時吸熱的氧化鐵用作氧源。 After the slag removal step, the CaO-based solvent and the oxygen source are supplied to the molten iron 5 remaining in the converter-type refining furnace, and as shown in FIG. 2(D), the molten iron 5 is subjected to dephosphorization treatment (dephosphorization treatment step). In the dephosphorization treatment step, the alkalinity of the slag in the furnace is adjusted to a range of 1.3 to 3.5. The oxygen source used in the dephosphorization treatment step is mainly composed of oxygen gas 8 from the top-blowing lance 2 in the same manner as the deodorization treatment, but iron oxide may be partially used. However, one of the objects of the present invention is to melt a large amount of cold iron source 7, and as described above, it is preferred to avoid the use of iron oxide which absorbs heat during heating and decomposition as an oxygen source as much as possible.

作為脫磷處理中使用的CaO系溶劑，可使用生石灰或碳酸鈣等。然而，並不限定於該些，亦可將含有40質量%以上的CaO且視需要而含有氟或氧化鋁、氧化鐵等其他成分的化合物用作脫磷處理時的CaO系溶劑。作為該CaO系溶劑的添加方法，可將粒狀及塊狀的溶劑自爐上的料斗投入，將粉狀的溶劑經由頂吹式噴槍2等投入。 As the CaO-based solvent used in the dephosphorization treatment, quicklime, calcium carbonate, or the like can be used. However, it is not limited to these, and a compound containing 40% by mass or more of CaO and optionally containing fluorine, alumina, or other components such as iron oxide may be used as the CaO-based solvent in the dephosphorization treatment. As a method of adding the CaO-based solvent, a granular or bulk solvent can be introduced from a hopper on the furnace, and a powdery solvent can be supplied through the top-blowing lance 2 or the like.

熔鐵中的磷由被供給的氧源中的氧所氧化而成為磷氧化物(P2O5)，該磷氧化物藉由CaO系溶劑的渣化而生成，在作為脫磷精煉劑發揮功能的熔渣中，作為3CaO‧P2O5的穩定形態的化 合物而被攝入，從而進行熔鐵5的脫磷反應。脫磷處理後，生成含有磷氧化物的脫磷熔渣。 Phosphorus in the molten iron is oxidized by oxygen in the supplied oxygen source to become a phosphorus oxide (P 2 O 5 ) which is formed by slag formation of a CaO-based solvent and functions as a dephosphorization refining agent. The functional slag is ingested as a compound of a stable form of 3CaO‧P 2 O 5 to carry out a dephosphorization reaction of the molten iron 5 . After the dephosphorization treatment, a dephosphorization slag containing phosphorus oxide is formed.

脫磷反應進行而熔鐵中磷濃度降低為規定的值後，結束脫磷處理。其次，如圖2(E)所示，將轉爐型精煉爐1向設置著流出口4的一側傾斜，將轉爐型精煉爐內的熔鐵5經由流出口4而向熔鐵保持容器(未圖示)流出(流出步驟)。 After the dephosphorization reaction proceeds and the phosphorus concentration in the molten iron is lowered to a predetermined value, the dephosphorization treatment is terminated. Next, as shown in Fig. 2(E), the converter type refining furnace 1 is inclined to the side where the outflow port 4 is provided, and the molten iron 5 in the converter type refining furnace is transferred to the molten iron holding container via the outflow port 4 (not Show) outflow (outflow step).

該流出步驟後，亦可不排出爐內的脫磷熔渣，而向轉爐型精煉爐1中裝入冷鐵源7及熔鐵5，開始下一次加料的脫矽處理步驟，而且，亦可在排出爐內的脫磷熔渣後，裝入冷鐵源7及熔鐵5，開始下一次加料的脫矽處理步驟。在使爐內生成的脫磷熔渣的全部或大半部分殘留於爐內而開始下一次加料的脫矽處理的情況下，可將上一次加料的脫磷熔渣所具有的熱量及鐵成分在下一次加料的脫矽處理中加以回收，並且可將上一次加料的脫磷熔渣中的CaO成分有效用作下一次加料的脫矽處理中的CaO源，從而可削減脫矽處理時的CaO系溶劑的使用量。 After the effluent step, the desulfurization slag in the furnace may not be discharged, and the cold iron source 7 and the molten iron 5 may be charged into the converter type refining furnace 1 to start the dislocation treatment step of the next feeding, and After the dephosphorization slag in the furnace is discharged, the cold iron source 7 and the molten iron 5 are charged, and the dislocation treatment step of the next feeding is started. When all or most of the dephosphorization slag produced in the furnace remains in the furnace and the next feeding deodorization treatment is started, the heat and iron component of the last dephosphorization slag can be It is recovered in the untwisting treatment of the primary feed, and the CaO component in the dephosphorization slag of the last addition can be effectively used as the CaO source in the dislocation treatment of the next feeding, thereby reducing the CaO system at the time of the dislocation treatment. The amount of solvent used.

本發明中，當如上述般對熔鐵5實施脫矽處理及脫磷處理時，除渣步驟中為了將規定量以上的脫矽熔渣6迅速地向爐外流出，而在脫矽處理中測定脫矽熔渣6的高度，以脫矽處理結束時間點測定的熔渣高度(自爐內的靜止時的熔鐵浴面至脫矽熔渣6的上端為止的距離)為目標範圍的方式，在脫矽處理中使脫矽熔渣6起泡。另外，本發明者等人確認，若脫矽處理結束時間點的脫矽熔渣6的起泡少，則脫矽熔渣6的流動性低，因而規定時間 內難以排出充分量的脫矽熔渣6。因此，為了在除渣步驟中迅速地使充分量的脫矽熔渣6自爐內流出，需要以在脫矽處理結束時成為規定的熔渣高度的範圍的方式，使脫矽熔渣6起泡。此處，熔渣的起泡是熔融熔渣包含氣泡而表觀上體積膨脹的現象。 In the present invention, when the molten iron 5 is subjected to the untwisting treatment and the dephosphorization treatment as described above, in the slag removing step, in order to rapidly discharge the predetermined amount or more of the mashing slag 6 to the outside of the furnace, in the detaching treatment The height of the slag slag 6 is measured, and the slag height (the distance from the molten iron bath surface at the time of stationary in the furnace to the upper end of the slag slag 6 in the furnace) measured at the time point of the devolatilization treatment is a target range. The untwisting slag 6 is foamed in the untwisting treatment. In addition, the inventors of the present invention have confirmed that if the foaming of the slag slag 6 at the end of the devolatilization treatment is small, the fluidity of the slag slag 6 is low, and thus the predetermined time is required. It is difficult to discharge a sufficient amount of the slag slag 6 therein. Therefore, in order to rapidly eject a sufficient amount of the slag slag 6 from the furnace in the slag removal step, it is necessary to cause the slag slag 6 to be in a range of a predetermined slag height at the end of the mash removal process. bubble. Here, the foaming of the slag is a phenomenon in which the molten slag contains bubbles and apparently expands in volume.

因此，本發明中使用的轉爐型精煉爐1需要具備測定爐內的熔渣高度的功能。 Therefore, the converter type refining furnace 1 used in the present invention needs to have a function of measuring the slag height in the furnace.

在圖1所示的本發明中所使用的轉爐型精煉爐1中，在轉爐型精煉爐1的爐口的上方，設置著用以回收自爐內產生的廢氣的罩(hood)12，在罩12的上部設置著用以將廢氣導入至集塵機的煙道11。罩12上設置著開口部13及開口部14，頂吹式噴槍2貫通開口部13而***至爐內，而且，設置著貫通開口部14而安裝在擬似隨機信號處理雷達方式微波距離計15(以下僅記作「微波熔渣位高計15」)的2根波導管16。在2根波導管16的前端，發送天線17及接收天線18分別設置在開口部14的正下方位置。即，構成為藉由微波熔渣位高計15測定爐內的脫矽熔渣6的高度。 In the converter type refining furnace 1 used in the present invention shown in Fig. 1, a hood 12 for collecting exhaust gas generated in the furnace is provided above the furnace opening of the converter type refining furnace 1, The upper portion of the cover 12 is provided with a flue 11 for introducing the exhaust gas to the dust collector. The cover 12 is provided with an opening 13 and an opening 14 , and the top-blowing lance 2 is inserted into the furnace through the opening 13 and is provided with a through-opening 14 and mounted on a pseudo-random signal processing radar type microwave distance meter 15 ( Hereinafter, only two waveguides 16 of "microwave slag level gauge 15" will be described. At the front end of the two waveguides 16, the transmitting antenna 17 and the receiving antenna 18 are respectively disposed at positions directly below the opening 14. That is, the height of the slag slag 6 in the furnace is measured by the microwave slag level height meter 15.

因起泡的脫矽熔渣6對於微波的反射率極小，為10-4以下，故本發明的一實施形態中使用雷達，該雷達利用由擬似隨機信號調變微波所得的信號，而提高了測定感度。作為擬似隨機信號，例如可使用自800MHz左右的高頻時脈信號組合適當的邏輯電路而產生的以6MHz左右的頻率重複相同波形的擬似隨機信號。上述情況為藉由時脈信號被輸入27次(128次)而循環一輪的邏輯電路產生擬似隨機信號的情況的示例。 Since the foaming de-slag slag 6 has a very small reflectance to microwaves of 10 - 4 or less, a radar is used in an embodiment of the present invention, and the radar is improved by a signal obtained by modulating a microwave by a pseudo-random signal. The sensitivity is measured. As the pseudo-random signal, for example, a pseudo-random signal of the same waveform can be repeated at a frequency of about 6 MHz, which is generated by combining an appropriate logic circuit from a high-frequency clock signal of about 800 MHz. With the above-described case when the clock signal is input 27 times (128 times) while the exemplary case where the pseudo random signal generation cycle of a logic circuit.

作為所使用的微波的載波，使用例如頻率約為10GHz的微波，並將其乘以擬似隨機信號而經調變的微波經由設置在爐上的罩12的開口部14的發送天線17而朝向轉爐型精煉爐1的內部放射。 As the carrier of the microwave to be used, for example, a microwave having a frequency of about 10 GHz is used, and this is multiplied by a pseudo-random signal, and the modulated microwave is directed toward the converter via the transmitting antenna 17 of the opening portion 14 of the cover 12 provided on the furnace. Internal emission of the type refining furnace 1.

此處，頻率10GHz的電磁波的空中的波長約為3.0cm，在頻率小於10GHz的情況下波長為上述3.0cm以上，比起轉爐型精煉爐內的粉塵或煙狀物的粒子而非常長，因而不易受到粉塵等的影響，並且因波長短，故有利於天線的小形化。而且，發送天線17及接收天線18例如使用號角天線，藉由大幅縮小指向性而儘可能地減小來自熔渣表面以外的反射波。微波的頻率低者不易受到粉塵等的影響，因此，作為本發明中所使用的微波，將頻率的上限值設為10GHz，低於10GHz的頻率較佳，更佳為8GHz以下。然而，若微波的頻率過低，則存在時間及距離的解析度降低的問題，並且需要天線的大型化，且在防止灰塵附著於天線方面欠佳，因而微波的頻率較佳設為2GHz以上。 Here, the wavelength of the electromagnetic wave having a frequency of 10 GHz is about 3.0 cm, and when the frequency is less than 10 GHz, the wavelength is 3.0 cm or more, which is very long compared with the particles of dust or smoke in the converter type refining furnace. It is less susceptible to dust and the like, and is short in wavelength, which is advantageous for miniaturization of the antenna. Further, the transmitting antenna 17 and the receiving antenna 18 use, for example, a horn antenna, and the reflected wave from the surface of the slag is reduced as much as possible by greatly reducing the directivity. The microwave having a low frequency is less susceptible to dust or the like. Therefore, as the microwave used in the present invention, the upper limit of the frequency is set to 10 GHz, and the frequency lower than 10 GHz is preferable, and more preferably 8 GHz or less. However, if the frequency of the microwave is too low, there is a problem that the resolution of time and distance is lowered, and the antenna is required to be increased in size, and the dust is prevented from adhering to the antenna. Therefore, the frequency of the microwave is preferably 2 GHz or more.

自發送天線17朝向轉爐型精煉爐內放射的電磁波在熔渣表面反射，並經由接收天線18而轉換為電信號。微波熔渣位高計15對接收器供給輸入信號的時機當然是從發送天線17放射電磁波的時機延遲了電磁波的傳播時間，該電磁波的傳播時間是指電磁波將直至轉爐型精煉爐內的熔渣位高為止的距離走了一個來回，直至到達接收天線18為止的時間。該傳播時間可藉由在接收波與發送波中比較經調變為微波的載波的擬似隨機信號的相位差 來進行測定。 Electromagnetic waves radiated from the transmitting antenna 17 toward the converter type refining furnace are reflected on the surface of the slag and converted into electric signals via the receiving antenna 18. The timing at which the microwave slag level gauge 15 supplies an input signal to the receiver is of course delayed by the electromagnetic wave propagation time from the transmitting antenna 17, and the propagation time of the electromagnetic wave means that the electromagnetic wave will reach the slag in the converter type refining furnace. The distance from the bit height goes back and forth until the time when the receiving antenna 18 is reached. The propagation time can be obtained by comparing the phase difference of the pseudo-random signal of the carrier modulated into the microwave in the received wave and the transmitted wave. To carry out the measurement.

此時，亦可根據調變為接收波與發送波的擬似隨機信號成分的時間相關函數，而直接求出傳播時間，但藉由利用稍微變更時脈頻率而產生的擬似隨機信號來進行信號處理，能夠大幅擴大時間相關函數的時間軸並進行解析度高的測定。 At this time, the propagation time can be directly obtained based on the time correlation function of the pseudo-random signal component of the received wave and the transmitted wave, but the signal processing is performed by using a pseudo-random signal generated by slightly changing the clock frequency. The time axis of the time-dependent function can be greatly expanded and the measurement with high resolution can be performed.

例如，對於自800MHz的高頻的時脈信號使用邏輯電路而產生的以約6MHz的頻率重複相同波形的擬似隨機信號，在利用自頻率改變了4kHz所得的時脈信號(例如800.004MHz)使用相同的邏輯電路而產生的擬似隨機信號的情況下，若將兩者的擬似隨機信號相乘，則當兩者的相位不一致時，相乘結果僅為時脈頻率程度以上的高頻成分，但當兩者的相位一致時，2個相同波形的擬似隨機信號的相乘結果中會產生直流成分或者低頻成分。因此，若進而藉由低通濾波器將頻率比擬似隨機信號的重複頻率程度高的信號成分去除，則檢測出在4kHz的週期內2個擬似隨機信號的相位一致的時機。這是由如下而實現：因兩者的擬似隨機信號中作為基準的時脈頻率僅相差4kHz，故相位差一點一點地變化，在4kHz的週期內相位僅有1次一致。 For example, a pseudo-random signal of the same waveform is generated at a frequency of about 6 MHz generated by using a logic circuit from a high-frequency clock signal of 800 MHz, and the same clock signal (for example, 800.004 MHz) obtained by changing the frequency from 4 kHz is used. In the case of a pseudo-random signal generated by a logic circuit, if the pseudo-random signals of the two are multiplied, when the phases of the two are inconsistent, the multiplication result is only a high-frequency component above the clock frequency, but when When the phases of the two are the same, a DC component or a low-frequency component is generated in the multiplication result of the pseudo-random signals of two identical waveforms. Therefore, if the signal component whose frequency is higher than the repetition frequency of the random signal is removed by the low-pass filter, the timing at which the phases of the two pseudo-random signals coincide in the period of 4 kHz is detected. This is achieved by the fact that the clock frequency as a reference in the quasi-random signals of the two differs by only 4 kHz, so the phase difference changes little by little, and the phase only coincides once in the period of 4 kHz.

這樣，約6MHz的擬似隨機信號的重複頻率的週期內的相位差，亦即時間延遲被轉換為4kHz的週期內的時間差，時間軸擴大至約1500倍，從而可檢測出接收波與發送波的擬似隨機信號的相位差。 Thus, the phase difference in the period of the repetition frequency of the pseudo-random random signal of about 6 MHz, that is, the time delay is converted into the time difference in the period of 4 kHz, and the time axis is expanded to about 1500 times, so that the received wave and the transmitted wave can be detected. The phase difference of a pseudo-random signal.

所接收到的反射波中包含來自各種路徑及對象物的反 射波，來自各個對象物的反射波中包含與反射強度及傳播時間量的相位延遲相對應的擬似隨機信號成分。對上述反射波，使用變更了上述時脈信號頻率而得的擬似隨機信號進行信號處理，若與同樣地進行了信號處理的發送波的信號相比，則傳播時間擴大至約1500倍，從而檢測出與來自各個對象物的反射波成分的傳播時間及強度相應的信號。 The received reflected wave contains the inverse from various paths and objects. In the radio wave, the reflected wave from each object includes a pseudo-random signal component corresponding to the phase delay of the reflection intensity and the amount of propagation time. The pseudo-random signal obtained by changing the frequency of the clock signal is subjected to signal processing on the reflected wave, and the propagation time is expanded to about 1500 times as compared with the signal of the transmission wave subjected to the signal processing in the same manner, thereby detecting A signal corresponding to the propagation time and intensity of the reflected wave component from each object.

對如上述般檢測出的信號，將自發送波的時間延遲換算為傳播時間，對該傳播時間乘以微波的傳播速度(3×108m/s)並除以2，藉此可算出直至與檢測出的信號相對應的對象物為止的距離。 For the signal detected as described above, the time delay from the transmitted wave is converted into the propagation time, and the propagation time is multiplied by the propagation speed of the microwave (3 × 10 8 m/s) and divided by 2, thereby calculating The distance from the object corresponding to the detected signal.

圖3是使上一次加料的脫磷處理中生成的脫磷熔渣殘留於爐內，在將該加料的熔鐵5裝入爐內後進行脫矽處理時，使用上述微波熔渣位高計15而採取到的反射波的信號的一例。圖3中表示成為反射波的發生源的對象物自天線算起的距離與其反射波的強度的關係。圖3的橫軸使用的是如下的值，該值是將自檢測出的信號的發送波的延遲時間換算為自發送天線17及接收天線18至對象物為止的距離所得。在進行如上述般信號處理的情況下，在4kHz的週期內獲得如圖3般的反射波的檢測信號，因而可進一步進行平均化處理而提高信號/雜訊比，並連續地計測熔渣位高的變化。 3 is a view showing that the dephosphorization slag generated in the dephosphorization treatment of the last feeding is left in the furnace, and the dissolving treatment is performed after the molten iron 5 is charged into the furnace, and the microwave slag height gauge is used. An example of a signal of a reflected wave taken at 15. FIG. 3 shows the relationship between the distance from the antenna of the object which is the source of the reflected wave and the intensity of the reflected wave. The horizontal axis of FIG. 3 is obtained by converting the delay time of the transmission wave from the detected signal into the distance from the transmitting antenna 17 and the receiving antenna 18 to the object. When the signal processing as described above is performed, the detection signal of the reflected wave as shown in FIG. 3 is obtained in the period of 4 kHz, so that the averaging processing can be further performed to increase the signal/noise ratio, and the slag level can be continuously measured. High change.

圖3中表示在多個位置具有峰值的反射波的檢測信號，關於強度小於某固定值的峰值(反射波的信號)，則為由來自爐體 耐火物或附著爐壁的原料金屬、或者頂吹式噴槍2的多重反射而引起的反射波的峰值。而且，在具有某固定值以上的強度的峰值位置中，將自天線算起的距離大於直至爐口為止的距離且最接近直至爐口為止的距離的峰值設為自熔渣表面算起的反射波的峰值。 Fig. 3 shows a detection signal of a reflected wave having a peak at a plurality of positions, and the peak (the signal of the reflected wave) whose intensity is smaller than a certain value is derived from the furnace body. The peak value of the reflected wave caused by the multiple reflection of the refractory or the raw material metal attached to the furnace wall or the top-blowing lance 2. Further, in the peak position having a certain fixed value or more, the distance from the antenna is larger than the distance up to the furnace mouth and the peak of the distance up to the furnace mouth is set as the reflection from the slag surface. The peak of the wave.

具體而言，在如圖3般的反射波的檢測信號中，將具有背景水準(background level)的100倍以上的強度的峰值中的、峰值位置大於直至爐口為止的距離且最接近直至爐口為止的距離的峰值設為與起泡的脫矽熔渣6的表面相對應的峰值。另外，圖3中，自天線至相當於爐口的位置為止的距離約為9m，自天線算起的距離為19m左右的範圍廣且大的峰值與熔鐵浴面相對應。 Specifically, in the detection signal of the reflected wave as shown in FIG. 3, the peak position among the peaks having the intensity of 100 times or more of the background level is larger than the distance up to the furnace mouth and is closest to the furnace. The peak of the distance from the mouth is set to a peak corresponding to the surface of the foamed slag 6 . Further, in Fig. 3, the distance from the antenna to the position corresponding to the furnace mouth is about 9 m, the distance from the antenna is about 19 m, and the large peak corresponds to the molten iron bath surface.

而且，自脫矽處理開始時產生位置(自天線算起的距離)未發生變化而是繼續存在的峰值可判斷為不與來自熔渣表面的反射波相對應，因而若在將上述峰值作為雜訊而加以去除後，如上述般判定與熔渣表面相對應的峰值，則能夠進行可靠性更高的計測。 Further, the position at which the position (the distance from the antenna) is not changed from the start of the dislocation process, but the peak which continues to exist can be judged not to correspond to the reflected wave from the surface of the slag, and therefore, if the above peak is used as the impurity After the removal is performed, the peak corresponding to the surface of the slag is determined as described above, and the measurement with higher reliability can be performed.

而且，如下的方法亦有效，可進行可靠性高的計測，即，在將自脫矽處理開始時位置繼續不發生變化地存在的峰值作為雜訊而加以去除後，將與爐口至熔鐵浴面為止的範圍的位置相對應的峰值中的與熔鐵浴面相對應的反射波的峰值加以去除，將強度最高的峰值判定為來自熔渣表面的反射波，並算出直至熔渣表面為止的距離。 Further, the following method is also effective, and high-reliability measurement can be performed, that is, after the peak which remains unchanged from the position at the start of the dislocation process is removed as noise, the furnace mouth is transferred to the molten iron. The peak of the reflected wave corresponding to the molten iron bath surface among the peaks corresponding to the position in the range from the bath surface is removed, and the peak having the highest intensity is determined as the reflected wave from the surface of the slag, and is calculated up to the surface of the slag. distance.

自利用上述方法而判定的熔渣表面相對於基準面(天線的位置)的高度中，減去根據此次加料中所投入的熔鐵及鐵屑量之和所推定的熔鐵浴面相對於基準面(天線的位置)的高度，並將其差的絕對值設為熔渣高度。圖4中表示根據藉由微波熔渣位高計15獲得的測定結果而求出脫矽處理中的爐內的熔渣高度的推移的示例。關於所獲得的熔渣高度的妥當性，藉由與起泡的脫矽熔渣6自爐口的噴出(熔渣的噴渣(slopping))的時機進行對照而確認。 From the height of the slag surface determined by the above method with respect to the reference surface (the position of the antenna), the molten iron bath surface estimated from the sum of the amount of the molten iron and the iron scraps input in the current feeding is subtracted from the reference. The height of the face (the position of the antenna), and the absolute value of the difference is set to the slag height. FIG. 4 shows an example of determining the transition of the slag height in the furnace during the untwisting process based on the measurement results obtained by the microwave slag level height meter 15. The validity of the obtained slag height was confirmed by comparison with the timing of the discharge of the foaming de-slagging slag 6 from the furnace mouth (slopping of the slag).

而且，本發明者等人對脫矽處理結束時的熔渣高度與中間除渣時間的關係、及脫矽處理結束時的熔渣高度與脫磷處理結束後的熔鐵中磷濃度的關係進行了調查。圖5表示脫矽處理結束時的熔渣高度與中間除渣時間的關係的調查結果，而且，圖6表示脫矽處理結束時的熔渣高度與脫磷處理結束後的熔鐵中磷濃度的關係的調查結果。圖5及圖6的橫軸由熔渣高度相對於爐內的自由區域(亦稱作「空塔部」，靜止時的熔鐵浴面與爐口之間的空間)的高度(靜止狀態下的熔鐵浴面與爐口之間的距離)的比率來表示。 Further, the inventors of the present invention performed a relationship between the slag height at the end of the devolatilization treatment and the intermediate slag removal time, and the relationship between the slag height at the end of the devolatilization treatment and the phosphorus concentration in the molten iron after the dephosphorization treatment. The investigation. Fig. 5 shows the results of investigations on the relationship between the slag height at the end of the devolatilization treatment and the intermediate slag removal time, and Fig. 6 shows the slag height at the end of the devolatilization treatment and the phosphorus concentration in the molten iron after the dephosphorization treatment is completed. The findings of the relationship. The horizontal axis of Figures 5 and 6 is the height of the slag height relative to the free area in the furnace (also referred to as the "empty tower", the space between the molten iron bath surface and the furnace mouth at rest) (at rest) The ratio of the distance between the molten iron bath surface and the furnace mouth is expressed.

若熔渣高度相對於爐內自由區域的高度的比率超過0.9，則脫矽熔渣6的起泡過於劇烈，需要採取除渣中暫時將爐豎立以便使脫矽熔渣6鎮靜的應對措施，從而導致中間除渣時間的延長。另一方面，在熔渣高度相對於爐內自由區域的高度的比率小於0.5的情況下，中間除渣時的脫矽熔渣6的排出性差，下一步 驟的脫磷處理中，脫矽熔渣6會過剩地殘留，因而熔渣的鹼度降低，脫磷處理後的熔鐵中的磷濃度增加。 If the ratio of the slag height to the height of the free area in the furnace exceeds 0.9, the foaming of the slag slag 6 is too severe, and it is necessary to take measures to temporarily erect the furnace in the slag to calm the slag slag 6. This results in an extension of the intermediate slag removal time. On the other hand, in the case where the ratio of the slag height to the height of the free area in the furnace is less than 0.5, the discharge property of the slag slag 6 at the time of intermediate slag removal is poor, and the next step In the dephosphorization treatment, the desulfurization slag 6 is excessively left, so that the alkalinity of the slag is lowered, and the phosphorus concentration in the molten iron after the dephosphorization treatment is increased.

亦即，在脫矽熔渣6的熔渣高度相對於爐內的自由區域的高度的比率為0.5以上、0.9以下的規定的範圍、較佳為0.7以上、0.9以下的規定的範圍的狀態下，結束脫矽處理，藉此在其後的除渣步驟中，實現迅速地將充分量的脫矽熔渣6排出至爐外，由此確認，在下一步驟的脫磷處理中，能夠以少的CaO系溶劑的使用量將熔鐵的磷濃度降低至低濃度。另外，認為上述規定的範圍的上限值及下限值根據爐內輪廓或爐口的形狀的不同而最佳值不同，因而更理想的是根據按照各精煉爐的實施形態所求出的圖5及圖6的資料，在上述範圍內適當調整上述上限值及下限值。 In other words, the ratio of the height of the slag of the slag 6 to the height of the free region in the furnace is in a predetermined range of 0.5 or more and 0.9 or less, preferably 0.7 or more and 0.9 or less. By the end of the degreasing treatment, it is possible to quickly discharge a sufficient amount of the degreasing slag 6 to the outside of the furnace, thereby confirming that it is possible to reduce the dephosphorization treatment in the next step. The amount of the CaO-based solvent used reduces the phosphorus concentration of the molten iron to a low concentration. Further, it is considered that the upper limit and the lower limit of the predetermined range are different depending on the contour of the furnace or the shape of the furnace mouth. Therefore, it is more preferable to obtain the map obtained according to the embodiment of each refining furnace. 5 and the data of Fig. 6, the upper limit and the lower limit are appropriately adjusted within the above range.

進而，本發明者等人進行使脫矽處理中的頂吹式噴槍2的頂吹條件及底吹氣體流量發生變化的實驗，並調查該些操作因素對熔渣高度的變化所造成的影響。圖7表示來自頂吹式噴槍2的送氧速度(氧氣供給流量)的變化對熔渣高度的變化速度造成的影響的調查結果，圖8表示頂吹式噴槍2的噴槍高度的變化對熔渣高度變化速度造成的影響的調查結果，圖9表示底吹氣體流量的變化對熔渣高度的變化速度造成的影響的調查結果。可知若提高來自頂吹式噴槍2的送氧速度則熔渣高度增大(圖7)，若增大頂吹式噴槍2的噴槍高度則熔渣高度增大(圖8)，而且，藉由增加來自底吹風口3的攪拌用氣體流量而熔渣高度減少(圖9)。此處，頂吹式噴槍2的噴槍高度為自頂吹式噴槍2的下端至靜止 狀態的熔鐵浴面為止的距離。 Further, the inventors of the present invention conducted experiments for changing the top blowing conditions and the bottom blowing gas flow rate of the top-blowing lance 2 in the detaching process, and investigated the influence of these operating factors on the change in the slag height. Fig. 7 is a view showing the result of investigation of the influence of the change in the oxygen supply rate (oxygen supply flow rate) from the top-blowing lance 2 on the rate of change of the slag height, and Fig. 8 shows the change in the height of the lance of the top-blowing lance 2 against the slag. As a result of the investigation of the influence of the height change rate, FIG. 9 shows the results of investigations on the influence of the change in the flow rate of the bottom blowing gas on the rate of change of the slag height. It can be seen that if the oxygen supply rate from the top-blowing lance 2 is increased, the slag height is increased (Fig. 7), and if the lance height of the top-blowing lance 2 is increased, the slag height is increased (Fig. 8), and The flow rate of the agitation gas from the bottom air outlet 3 is increased and the slag height is decreased (Fig. 9). Here, the height of the lance of the top-blowing lance 2 is from the lower end of the top-blowing lance 2 to stationary The distance from the molten iron bath surface in the state.

而且，熔渣組成對熔渣高度造成的影響亦大，存在鹼度越低、氧化鐵濃度越高、或氧化鋁濃度越高則熔渣高度越大的傾向，因而為了調整熔渣組成，基於熔渣高度的測定結果來進行造渣劑的投入亦有效。進而，在進行使熔渣高度減少的調整時，使用固體的冷卻劑或氣體發生物質等起泡鎮靜材料亦有效。 Moreover, the slag composition has a large influence on the slag height, and the lower the alkalinity, the higher the iron oxide concentration, or the higher the alumina concentration, the higher the slag height. Therefore, in order to adjust the slag composition, based on The measurement result of the slag height is also effective for the input of the slag forming agent. Further, in the adjustment for reducing the slag height, it is also effective to use a foaming sedating material such as a solid coolant or a gas generating material.

即，本發明中，較佳為脫矽處理中對爐內的脫矽熔渣6的高度進行測定，並且根據該測定結果，對選自來自頂吹式噴槍2的氣態氧源的供給流量、頂吹式噴槍2的噴槍高度、來自底吹風口3的攪拌用氣體的供給流量、爐內的熔渣的組成、起泡鎮靜材料的投入量所組成的群組中的至少1種進行調整，以藉由該調整而爐內的脫矽熔渣6的高度為規定的範圍內的方式進行控制。藉此，可容易地實現將脫矽處理結束時的熔渣高度相對於自由區域的高度的比率調整為上述規定的範圍。 That is, in the present invention, it is preferable to measure the height of the slag slag 6 in the furnace during the detachment treatment, and based on the measurement result, the supply flow rate of the gaseous oxygen source selected from the top-blowing lance 2, At least one of the group consisting of the height of the lance of the top-blowing lance 2, the supply flow rate of the agitation gas from the bottom air outlet 3, the composition of the slag in the furnace, and the input amount of the foaming sedative material is adjusted. The height of the slag slag 6 in the furnace is controlled within the predetermined range by this adjustment. Thereby, it is possible to easily adjust the ratio of the slag height at the end of the untwisting process to the height of the free region to the above-described predetermined range.

爐內的熔渣高度的測定不限於脫矽處理，脫磷處理中亦可根據上述來進行。脫磷處理中，以脫磷熔渣不會自爐口噴出(噴渣)的方式進行控制，藉此抑制添加的CaO系溶劑的噴出損失量，從而可進行有效率的脫磷處理。即，脫磷處理中，將熔渣高度相對於爐內的自由區域的高度的比率調整為小於1.0即可。脫磷處理中，亦較佳為使用上述說明的微波熔渣位高計15來測定熔渣高度。 The measurement of the slag height in the furnace is not limited to the deodorization treatment, and the dephosphorization treatment may be carried out in accordance with the above. In the dephosphorization treatment, the dephosphorization slag is controlled so as not to be ejected from the furnace mouth (slag spraying), thereby suppressing the amount of discharge loss of the added CaO-based solvent, thereby enabling efficient dephosphorization treatment. That is, in the dephosphorization treatment, the ratio of the slag height to the height of the free region in the furnace may be adjusted to be less than 1.0. In the dephosphorization treatment, it is also preferred to measure the slag height using the microwave slag level gauge 15 described above.

而且，本發明中，除渣步驟中的脫矽熔渣6的除渣率(除渣率(質量%)=(排出熔渣質量)×100/[(脫矽處理步驟中生成 的熔渣質量)+(上一次加料的殘留熔渣質量)])較佳為確保30質量%以上。這是因為，在其後的脫磷處理步驟中進行脫磷反應需要將脫磷熔渣的鹼度調整為1.3~3.5，若除渣率低於30質量%，則脫磷處理步驟中應添加的CaO系溶劑的量增多。而且，若殘留的脫矽熔渣量過多，則脫磷處理中的熔渣量增多，脫磷處理中的熔渣起泡便無法抑制，亦有熔渣自轉爐型精煉爐1的爐口噴出而引起操作障礙之虞。 Further, in the present invention, the slag removal rate (slag removal rate (% by mass) = (discharge slag mass) × 100 / [(discharge treatment step) generated in the slag removal step 6 The slag mass) + (the residual slag mass of the last charge)]) is preferably 30% by mass or more. This is because the dephosphorization reaction in the subsequent dephosphorization treatment step needs to adjust the alkalinity of the dephosphorization slag to 1.3 to 3.5. If the slag removal rate is less than 30% by mass, the dephosphorization treatment step should be added. The amount of CaO-based solvent is increased. Further, if the amount of residual slag remaining is too large, the amount of slag in the dephosphorization treatment increases, and the slag foaming in the dephosphorization treatment cannot be suppressed, and the slag is ejected from the mouth of the converter type refining furnace 1. And cause the obstacles of operation.

而且，為了增大脫矽熔渣6的除渣率，在脫矽處理結束時，較佳為脫矽熔渣6的鹼度設為0.5以上、1.5以下，且，熔鐵溫度或脫矽熔渣6的溫度設為1280℃以上。在脫矽熔渣6的鹼度小於0.5的情況下，黏度上升而熔渣的流動性降低，容易導致排出速度或除渣率的降低，在鹼度超過1.5的情況下，因產生固相熔渣而熔渣流動性降低。而且，熔渣溫度低於1280℃亦同樣地產生由固相熔渣的增加引起的熔渣流動性的降低、以及液相熔渣自身的黏性上升，因此脫矽熔渣6的流動性降低而容易導致熔渣的排出速度或除渣率的降低。 Further, in order to increase the slag removal rate of the slag slag 6, it is preferable that the alkalinity of the slag slag 6 is 0.5 or more and 1.5 or less at the end of the mashing treatment, and the molten iron temperature or the melting temperature is melted. The temperature of the slag 6 is set to 1280 ° C or higher. When the alkalinity of the slag slag 6 is less than 0.5, the viscosity increases and the fluidity of the slag decreases, which tends to cause a decrease in the discharge rate or the slag removal rate. When the alkalinity exceeds 1.5, solid phase fusion occurs. The slag and the slag fluidity are lowered. Further, when the slag temperature is lower than 1,280 ° C, the fluidity of the slag due to the increase in the solid phase slag is lowered, and the viscosity of the liquid slag itself is increased, so that the fluidity of the slag slag 6 is lowered. It is easy to cause a decrease in the discharge speed or the slag removal rate of the slag.

本發明者等人對如下述般製造的土木工程用的熔渣製品調查各種特性，即，使上述除渣步驟中排出至熔渣罐的脫矽熔渣6自熔渣罐向場地(yard)放流而固化，然後，將其粉碎為粒徑30mm左右以下。而且，根據該調查結果，而對可獲得適合於各種土木工程用材料的體積比重相對較小的熔渣的熔鐵的預備處理方法進行進一步研究。 The inventors of the present invention investigated various characteristics of a slag product for civil engineering manufactured as follows, that is, the slag slag 6 discharged to the slag tank in the slag removing step from the slag tank to the yard It is allowed to flow and solidified, and then it is pulverized to a particle diameter of about 30 mm or less. Further, based on the results of the investigation, a preliminary treatment method for obtaining a molten iron which is suitable for various slags having a relatively small specific gravity of materials for civil engineering is further studied.

規定的粒度及壓實狀態下的脫磷熔渣的單位體積質量為2.0kg/L~2.3kg/L左右，比天然土石材的1.6kg/L~1.8kg/L大。因此，脫磷熔渣例如適合於期望對波浪的穩定性高等質量大的材料的用途，相反，難以適合於擔心助長重力的不穩定性的土木工程用途，而且，亦存在因體積比重大故輸送費用增大的缺點。 The unit weight of the dephosphorization slag under the specified particle size and compaction state is about 2.0 kg/L to 2.3 kg/L, which is larger than 1.6 kg/L to 1.8 kg/L of natural earth stone. Therefore, the dephosphorization slag is suitable, for example, for use in a material having a high quality such as high stability against waves, and conversely, it is difficult to be suitable for civil engineering applications that are worried about the instability of gravity, and also because of a large volume ratio. The disadvantage of increased costs.

因此，為了極力地降低體積比重大的脫磷熔渣的產生量，將脫磷熔渣轉換為低體積比重的脫矽熔渣6，較佳為採用重複如下順序而進行的預備處理方法，即，在上一次加料的脫磷處理步驟後，使爐內的熔鐵流出後，在並不排出爐內的脫磷熔渣，而使上一次加料的脫磷熔渣殘留爐內的狀態下裝入新的熔鐵，並對該熔鐵實施脫矽處理步驟，該脫矽處理後，藉由除渣步驟將脫矽熔渣6的一部分自精煉爐中排出，然後，對殘留於爐內的熔鐵實施脫磷處理步驟。此時，較佳為，在脫矽處理結束時，將脫矽熔渣6的鹼度設為0.8以上、1.5以下，熔鐵溫度或脫矽熔渣6的溫度設為1280℃以上、1380℃以下，熔鐵中矽含量設為0.10質量%以下，且，在除渣步驟中，排出脫矽熔渣6的30質量%以上。 Therefore, in order to reduce the amount of dephosphorization slag having a large volume ratio as much as possible, it is preferable to convert the dephosphorization slag into the decarburization slag 6 having a low bulk specific gravity, and it is preferable to adopt a preliminary treatment method in which the following procedure is repeated, that is, After the dephosphorization treatment step of the last feeding, after the molten iron in the furnace is discharged, the dephosphorization slag in the furnace is not discharged, and the dephosphorization slag of the last feeding is left in the state of the furnace. Introducing a new molten iron, and performing a deodorizing treatment step on the molten iron. After the deodorizing treatment, a part of the desulfurization slag 6 is discharged from the refining furnace by a dross removing step, and then, the remaining in the furnace is left. The molten iron is subjected to a dephosphorization treatment step. In this case, it is preferable that the alkalinity of the mashing slag 6 is 0.8 or more and 1.5 or less at the end of the mashing treatment, and the temperature of the molten iron or the temperature of the slag slag 6 is set to 1280 ° C or more and 1380 ° C. In the slag removal step, 30% by mass or more of the slag slag 6 is discharged in the slag removal step.

藉由將脫矽熔渣6的鹼度設為0.8以上、1.5以下，熔鐵溫度或脫矽熔渣6的溫度設為1280℃以上、1380℃以下，而可防止自上一次加料的脫磷熔渣向熔鐵的複磷，且有效率地進行除渣步驟中的脫矽熔渣6的排出。此處，脫矽處理結束時，因脫矽熔渣6的溫度接近熔鐵溫度，故可將熔鐵溫度或脫矽熔渣6的溫度中的任一個作為指標。藉由將熱電偶浸漬於熔鐵而可測定熔鐵溫 度，亦可代替測定值，而使用根據脫矽處理前的熔鐵的溫度及成分、鐵屑等各種冷鐵源的使用量、生石灰等各種副原料的使用量、矽鐵(silicon iron)等各種升熱劑的使用量、以及氧氣供給量等操作條件，計算熱平衡而算出的熔鐵溫度。 By setting the alkalinity of the slag slag 6 to 0.8 or more and 1.5 or less, the molten iron temperature or the temperature of the slag slag 6 is set to 1280 ° C or more and 1380 ° C or less, thereby preventing dephosphorization from the last feeding. The slag is rephosphorized to the molten iron, and the discharge of the slag slag 6 in the slag removal step is efficiently performed. Here, at the end of the untwisting treatment, since the temperature of the untwisting slag 6 is close to the molten iron temperature, any one of the molten iron temperature and the temperature of the untwisting slag 6 can be used as an index. Melting iron temperature can be determined by immersing a thermocouple in a molten iron In addition to the measured value, the amount of various molten iron sources such as iron scraps, the amount of various raw materials such as quicklime, and the use of silicon iron, etc., may be used in place of the temperature and composition of the molten iron before the dislocation treatment. The molten iron temperature calculated by calculating the heat balance is calculated using operating conditions such as the amount of the heat-increasing agent and the oxygen supply amount.

而且，藉由將脫矽處理後的熔鐵中矽含量設為0.10質量%以下，即便熔渣中氧化鐵濃度相對降低，脫矽處理中由脫碳反應引起的CO氣體產生變得活躍，因而亦促進脫矽熔渣6的起泡，在脫矽處理結束時提高熔渣高度方面有利。而且，該情況下，除渣步驟中亦維持脫矽熔渣6的起泡並將熔渣高度維持得高，因而在提高脫矽熔渣6的排出效率方面亦有利。 In addition, by setting the cerium content in the molten iron after the deuteration treatment to 0.10% by mass or less, even if the iron oxide concentration in the slag is relatively lowered, the generation of CO gas by the decarburization reaction in the deodorization treatment becomes active. It also promotes the foaming of the slag slag 6, and is advantageous in terms of increasing the slag height at the end of the mashing treatment. Further, in this case, in the slag removing step, the foaming of the slag slag 6 is maintained and the slag height is maintained high, which is also advantageous in improving the discharge efficiency of the slag slag 6.

除渣步驟中的脫矽熔渣6的除渣率較佳設為30質量%以上。藉此，不會使上一次加料的脫磷熔渣在爐內過度地累積，亦不會導致脫磷處理步驟中的熔渣鹼度的過度降低，可在脫磷處理步驟中抑制生石灰等脫磷劑的使用量從而降低熔鐵中磷濃度。 The slag removal rate of the slag slag 6 in the slag removal step is preferably set to 30% by mass or more. Thereby, the dephosphorization slag of the last feeding is not excessively accumulated in the furnace, and the slag basicity in the dephosphorization treatment step is not excessively lowered, and the quicklime or the like can be suppressed in the dephosphorization treatment step. The amount of phosphorus used thereby reduces the concentration of phosphorus in the molten iron.

如上述般滿足脫矽處理結束時的條件，且測定脫矽處理結束時的爐內的熔渣高度，以經測定的熔渣高度相對於爐內自由區域的高度為0.5~0.9等規定的比率的方式進行調整，並進行除渣步驟，藉此可在相對較短的時間內以高除渣率將脫矽熔渣6自轉爐型精煉爐1排出。在使如此排出至熔渣罐的脫矽熔渣6進一步自熔渣罐向場地放流而固化，然後粉碎為粒徑30mm左右以下而製造的土木工程用的熔渣製品中，粒子內含有相對較小的氣泡，因而單位體積質量降低至1.2kg/L左右以下。結果，適合於 期望低比重的用途，並且亦獲得降低施工單位體積的搬運費用的效果。 The conditions at the end of the dislocation treatment are satisfied as described above, and the slag height in the furnace at the end of the dislocation treatment is measured, and the height of the measured slag height relative to the free area in the furnace is set to a predetermined ratio of 0.5 to 0.9. The manner of adjustment is carried out, and a slag removing step is performed, whereby the mashing slag 6 can be discharged from the converter type refining furnace 1 at a high slag removal rate in a relatively short period of time. The slag slag 6 thus discharged to the slag tank is further discharged from the slag tank to the site to be solidified, and then pulverized into a slag product for civil engineering manufactured to have a particle diameter of about 30 mm or less, and the particles are relatively contained. Small bubbles, so the mass per unit volume is reduced to about 1.2 kg/L or less. The result is suitable for The use of a low specific gravity is desired, and the effect of reducing the handling cost per unit volume of the construction is also obtained.

為了穩定地製造單位體積質量小的熔渣製品，理想的是將脫矽處理結束時的脫矽熔渣6的鹼度設為0.8以上、1.25以下，熔渣溫度設為1360℃以下而增大黏度；將脫矽處理結束時的熔渣中的磷酸(P2O5)含量設為2質量%以上而降低表面張力；在自熔渣罐向場地放流時，使用傾斜的場地，或一邊使熔渣罐移動一邊放流，藉此使放流的熔渣大範圍地分散，從而提高脫矽熔渣6的冷卻速度。另外，在脫矽處理結束時的熔渣高度相對於爐內自由區域的高度以小於0.5的比率進行除渣步驟的加料群組中，脫矽熔渣6的平均除渣率小於30質量%，並且平均單位體積質量增大至1.3kg/L左右。 In order to stably produce a slag product having a small mass per unit volume, it is preferable to increase the alkalinity of the slag slag 6 at the end of the mashing treatment to 0.8 or more and 1.25 or less, and to increase the slag temperature to 1360 ° C or less. Viscosity; the content of phosphoric acid (P 2 O 5 ) in the slag at the end of the deodorization treatment is 2% by mass or more to reduce the surface tension; when the self-slag tank is discharged to the site, the inclined site is used, or one side is used The slag tank is moved while being discharged, whereby the discharged slag is widely dispersed, thereby increasing the cooling rate of the slag slag 6. Further, in the charging group in which the slag height at the end of the devolatilization treatment is performed at a ratio of less than 0.5 with respect to the height of the free area in the furnace, the average slag removal rate of the slag slag 6 is less than 30% by mass. And the average unit volume mass is increased to about 1.3 kg/L.

如以上說明般，根據本發明，在使用一個轉爐型精煉爐1，將熔鐵5的脫矽處理與脫磷處理隔著中途的除渣步驟而連續地進行的熔鐵的預備處理中，在脫矽處理時，在起泡的脫矽熔渣6的高度相對於爐內自由區域的高度的比率為規定範圍的狀態下結束脫矽處理，因而在其後的除渣步驟中，實現迅速地將充分量的脫矽熔渣6排出至爐外。 As described above, according to the present invention, in the preparation process of the molten iron which is continuously performed by using the single-type refining furnace 1 and the degreasing treatment and the dephosphorization treatment in the middle of the molten iron 5, At the time of the dislocation treatment, the deodorization treatment is terminated in a state where the ratio of the height of the foamed desulfurization slag 6 to the height of the free area in the furnace is within a predetermined range, so that in the subsequent slag removal step, rapid realization is achieved. A sufficient amount of the slag slag 6 is discharged to the outside of the furnace.

另外，本發明並不限於上述說明的範圍，可進行各種變更。例如，上述說明中，使用微波熔渣位高計15來測定熔渣高度，但亦可根據爐內的高度方向溫度分佈的測定、安裝在頂吹式噴槍或爐體的振動計的測定值、自爐體產生的音量的測定值等的熔渣 面的檢測資訊來測定熔渣高度。 Further, the present invention is not limited to the scope described above, and various modifications can be made. For example, in the above description, the slag height is measured using the microwave slag level height meter 15, but the measurement of the temperature distribution in the height direction of the furnace, the measurement value of the vibrating meter attached to the top-blowing lance or the furnace body, Slag such as measured value of volume generated from furnace body Surface inspection information to determine the slag height.

實施例 Example

使用圖1所示的容量330噸的轉爐型精煉爐，分別以20次加料為單位而實施本發明的熔鐵預備處理(本發明例1~本發明例3)、以及藉由微波熔渣位高計測定熔渣高度但不進行熔渣高度的控制的現有方法的熔鐵預備處理(比較例1、比較例2)。預備處理結束時的熔鐵中磷濃度的目標值均設為0.030質量%。 The molten iron preparation process of the present invention (Examples 1 to 3 of the present invention) and the microwave slag level of the present invention were carried out in units of 20 feeds, respectively, using a converter type refining furnace having a capacity of 330 tons as shown in Fig. 1 . The molten iron preparation process (Comparative Example 1 and Comparative Example 2) of the conventional method of measuring the slag height but not controlling the slag height. The target value of the phosphorus concentration in the molten iron at the end of the preliminary treatment was set to 0.030% by mass.

本發明例1中，脫矽處理中，使用微波熔渣位高計來測定氧吹煉中的熔渣高度，並對來自頂吹式噴槍的送氧速度、噴槍高度、攪拌用氣體流量中的至少1種進行調整，測定出的熔渣高度相對於爐內的自由區域的高度的比率調整為如下：該比率在結束供給藉由將脫矽氧效率假定為50%而獲得的脫矽中所需要的氧量即脫矽處理結束時間點為0.5~0.9，進行中間除渣，然後，藉由氧吹煉而繼續進行脫磷處理。 In the first example of the present invention, the slag height in the oxygen blowing is measured using a microwave slag leveler in the mashing process, and the oxygen supply rate from the top-blowing lance, the height of the lance, and the gas flow rate for stirring are used. At least one of the adjustments is made, and the ratio of the measured slag height to the height of the free area in the furnace is adjusted as follows: the ratio is at the end of the supply by the assumption that the deoxidation efficiency is assumed to be 50%. The amount of oxygen required, that is, the end time of the deodorization treatment is 0.5 to 0.9, intermediate slag removal is performed, and then the dephosphorization treatment is continued by oxygen blowing.

本發明例2中，脫矽處理中，使用微波熔渣位高計來測定氧吹煉中的熔渣高度，並對來自頂吹式噴槍的送氧速度、噴槍高度、攪拌用氣體流量中的至少1種進行調整，欲將測定出的熔渣高度相對於爐內的自由區域的高度的比率調整為如下：該比率在結束供給藉由將脫矽氧效率假定為50%而獲得的脫矽中所需要的氧量的時間點為0.5以上，但經過該時間後，熔渣高度相對於爐內的自由區域的高度的比率小於0.5，因而延長氧吹煉時間，在熔渣高度相對於自由區域的高度達到0.5的時間點結束脫矽處理而 進行中間除渣，然後，藉由氧吹煉而繼續進行脫磷處理。 In the second example of the present invention, the slag height in the oxygen blowing is measured using a microwave slag leveler in the mashing process, and the oxygen supply rate from the top-blowing lance, the height of the lance, and the gas flow rate for stirring are used. At least one of the adjustments is made, and the ratio of the measured slag height to the height of the free area in the furnace is adjusted as follows: the ratio is obtained at the end of the supply by the assumption that the deoxidation efficiency is assumed to be 50%. The time point of the amount of oxygen required is 0.5 or more, but after this time, the ratio of the height of the slag to the height of the free area in the furnace is less than 0.5, thereby prolonging the oxygen blowing time, and the slag height is relatively free. When the height of the area reaches 0.5, the dislocation process ends. Intermediate slag removal is carried out, and then the dephosphorization treatment is continued by oxygen blowing.

本發明例3中，在脫矽處理中進行與本發明例1相同的控制後進行中間除渣，然後，脫磷處理中使用微波熔渣位高計來測定氧吹煉中的熔渣高度，當熔渣高度相對於爐內的自由區域的高度的比率為0.8以上時，對來自頂吹式噴槍的送氧速度、噴槍高度、攪拌用氣體流量中的至少1種進行調整，以熔渣高度相對於爐內的自由區域的高度的比率小於1.0的方式進行調整而進行脫磷處理。 In the third example of the present invention, the same control as in the first embodiment of the present invention is carried out in the untwisting treatment, and then the intermediate slag is removed, and then the slag height in the oxygen blowing is measured by using the microwave slag height gauge in the dephosphorization treatment. When the ratio of the slag height to the height of the free area in the furnace is 0.8 or more, at least one of the oxygen supply rate from the top-blowing lance, the lance height, and the stirring gas flow rate is adjusted to the slag height. The dephosphorization treatment is performed so as to be adjusted so that the ratio of the height of the free area in the furnace is less than 1.0.

比較例1及比較例2中，在結束供給藉由將脫矽氧效率假定為50%而獲得的脫矽中所需要的氧量的時間點結束脫矽處理，進行中間除渣，然後，藉由氧吹煉繼續進行脫磷處理。此處，熔鐵溫度為1300℃以上為比較例1，熔鐵溫度小於1300℃為比較例2。將比較例分為比較例1與比較例2的理由在於，在熔鐵溫度高達1300℃以上的情況下，促進熔渣的渣化，熔渣高度向高位推移，與此相對，在熔鐵溫度小於1300℃的情況下，熔渣高度向低位推移。 In Comparative Example 1 and Comparative Example 2, the deodorization treatment was terminated at the end of the supply of the amount of oxygen required for the decarburization obtained by assuming that the desulfurization efficiency was assumed to be 50%, and intermediate dedusting was performed, and then borrowed. The dephosphorization treatment is continued by oxygen blowing. Here, the molten iron temperature was 1300 ° C or more as Comparative Example 1, and the molten iron temperature was less than 1300 ° C as Comparative Example 2. The reason why the comparative example is divided into the comparative example 1 and the comparative example 2 is that when the molten iron temperature is as high as 1300 ° C or more, the slag of the slag is promoted, and the slag height is shifted to a high position, whereas the molten iron temperature is relatively high. In the case of less than 1300 ° C, the slag height is shifted to a lower position.

本發明例1~本發明例3及比較例1、比較例2中，均以如下作為基準條件，即，脫矽處理時的送氧速度為30000Nm3/hr，噴槍高度為2.5m，底吹氣體流量為1200Nm3/hr。而且，以如下作為基準條件，即，脫磷處理時的送氧速度為25000Nm3/hr，噴槍高度為2.1m，底吹氣體流量為1200Nm3/hr。作為底吹氣體，脫矽處理及脫磷處理中均使用氮氣。 In the first to third examples of the present invention, the third embodiment of the present invention, the comparative example 1, and the comparative example 2, the oxygen supply rate at the time of the decanting treatment was 30,000 Nm 3 /hr, and the height of the lance was 2.5 m. The gas flow rate was 1200 Nm 3 /hr. Further, the following conditions were used as the reference conditions, that is, the oxygen supply rate at the time of dephosphorization treatment was 25,000 Nm 3 /hr, the height of the spray gun was 2.1 m, and the flow rate of the bottom blowing gas was 1200 Nm 3 /hr. As the bottom blowing gas, nitrogen gas is used in both the deuteration treatment and the dephosphorization treatment.

表1表示本發明例1~本發明例3及比較例1、比較例2的各自代表例的試驗結果。而且，圖10中表示本發明例1、本發明例2及比較例1、比較例2的各自代表例的脫矽處理中熔渣高度相對於爐內的自由區域的高度的比率的推移。而且，圖11中表示本發明例3、比較例2的各自代表例的脫磷處理中熔渣高度相對於爐內的自由區域的高度的比率的推移。表1、圖10、圖11中各自的代表例由本發明例1~本發明例3及比較例1、比較例2表示。 Table 1 shows the test results of representative examples of Examples 1 to 3 of the present invention, Comparative Example 1 and Comparative Example 2. Moreover, FIG. 10 shows the transition of the ratio of the slag height to the height of the free area in the furnace in the dislocation process of each of the representative examples of the present invention example 1, the inventive example 2, and the comparative example 1 and the comparative example 2. Further, Fig. 11 shows the transition of the ratio of the slag height to the height of the free region in the furnace in the dephosphorization treatment of each of the representative examples of the inventive examples 3 and 2. Representative examples of each of Table 1, FIG. 10, and FIG. 11 are shown in Inventive Example 1 to Inventive Example 3, Comparative Example 1, and Comparative Example 2.

表1所示的本發明例1中，因熔鐵溫度高，脫矽處理初期的渣化速度高，故熔渣高度推移得高。因此，自脫矽處理開始2分鐘後使底吹氣體流量增加至2400Nm3/hr。藉此，熔渣高度的增加得到抑制，在結束供給藉由將脫矽氧效率假定為50%而獲得的脫矽中所需要的氧量的時間點，熔渣高度相對於爐內的自由區域 的高度的比率為0.8。 In the first example of the present invention shown in Table 1, since the molten iron temperature is high and the slag formation speed at the initial stage of the deodorization treatment is high, the slag height is highly changed. Therefore, the bottom blowing gas flow rate was increased to 2400 Nm 3 /hr 2 minutes after the start of the decanting treatment. Thereby, the increase in the slag height is suppressed, and the slag height is relative to the free area in the furnace at the end of the supply of the amount of oxygen required for the decarburization obtained by assuming the deaeration efficiency is assumed to be 50%. The ratio of the height is 0.8.

與此相對，在使用與本發明例1同等的溫度的熔鐵的表1所示的比較例1中，因未進行熔渣高度的控制，故脫矽處理結束時間點的熔渣高度相對於爐內的自由區域的高度的比率為1.0，中間除渣時熔渣的流出劇烈，將暫時傾斜的爐再次立起，使用鎮靜劑降低熔渣高度後再次進行中間除渣。藉此，中間除渣時間延長。 On the other hand, in Comparative Example 1 shown in Table 1 in which molten iron having the same temperature as in the first embodiment of the present invention was used, since the slag height was not controlled, the slag height at the end of the devolatilization treatment was relative to The ratio of the height of the free area in the furnace was 1.0, and the outflow of the slag was severe during the intermediate slag removal, and the temporarily inclined furnace was erected again, and the intermediate slag was again performed after the slag height was lowered using a sedative. Thereby, the intermediate slag removal time is extended.

表1所示的本發明例2中，熔鐵溫度低，脫矽處理初期的渣化速度低，因而熔渣高度推移得低。因此，脫矽處理開始2分鐘後使來自頂吹式噴槍的送氧速度增加至50000Nm3/hr，且，噴槍高度亦增加至3.5m而進行氧吹煉。然而，在結束供給藉由將脫矽氧效率假定為50%而獲得的脫矽中所需要的氧量的時間點，熔渣高度相對於爐內的自由區域的高度的比率小於0.5。因此，繼續進行氧吹煉的脫矽處理，在熔渣高度相對於爐內的自由區域的高度的比率為0.5的時間點結束脫矽處理，然後，進行中間除渣。藉此，除渣步驟中的除渣率高達70%。 In the second example of the present invention shown in Table 1, the molten iron temperature was low, and the slag formation speed at the initial stage of the deodorization treatment was low, so that the slag height was lowered. Therefore, 2 minutes after the start of the deodorization treatment, the oxygen supply rate from the top-blowing lance was increased to 50,000 Nm 3 /hr, and the height of the lance was also increased to 3.5 m to perform oxygen blowing. However, the ratio of the slag height to the height of the free area in the furnace is less than 0.5 at the end of the supply of the amount of oxygen required for the decarburization obtained by assuming the deaeration efficiency is assumed to be 50%. Therefore, the deodorization treatment of the oxygen blowing is continued, and the deodorization treatment is terminated at a time point when the ratio of the slag height to the height of the free region in the furnace is 0.5, and then the intermediate slag is performed. Thereby, the slag removal rate in the slag removal step is as high as 70%.

與此相對，在使用與本發明例2同等的溫度的熔鐵的表1所示的比較例2中，因未進行熔渣高度的控制，故在結束供給藉由將脫矽氧效率假定為50%而獲得的脫矽中所需要的氧量的時間點，熔渣高度相對於爐內的自由區域的高度小於0.5。該狀態下進行中間除渣的結果為，除渣率降低，其後的脫磷處理的鹼度降低而引起脫磷不良。 On the other hand, in Comparative Example 2 shown in Table 1 in which molten iron having the same temperature as in the second embodiment of the present invention was used, since the control of the slag height was not performed, the supply was terminated by the assumption that the deoxidation efficiency was At a time point of 50% of the amount of oxygen required for the dislocation, the height of the slag is less than 0.5 with respect to the free area in the furnace. As a result of performing intermediate slag removal in this state, the slag removal rate is lowered, and the alkalinity of the subsequent dephosphorization treatment is lowered to cause dephosphorization failure.

表1所示的本發明例3中，在脫矽處理時控制熔渣高 度，並且脫磷處理中，以熔渣高度相對於爐內的自由區域的高度的比率小於1.0的方式，實施相對於基準值而使送氧速度為±5000Nm3/hr的範圍、噴槍高度為±0.5m的範圍、底吹氣體流量為±1200Nm3/hr的範圍中的任1種或2種以上的調整。藉此，可防止脫磷處理中的噴渣，可防止裝入至爐內的CaO系溶劑的爐外噴出，結果，可降低脫磷處理結束時的熔鐵中的磷濃度。與此相對，在比較例2中，脫磷處理中產生噴渣(熔渣噴出)，脫磷處理結束時的熔鐵中的磷濃度無法達成目標值。 In the third embodiment of the present invention shown in Table 1, the slag height is controlled at the time of the deodorization treatment, and in the dephosphorization treatment, the ratio of the slag height to the height of the free region in the furnace is less than 1.0, The reference value is adjusted in the range of ±5000 Nm 3 /hr, the range of the lance height of ±0.5 m, and the range of the bottom blowing gas flow rate of ±1200 Nm 3 /hr. Thereby, it is possible to prevent slag from being sprayed in the dephosphorization treatment, and it is possible to prevent the CaO-based solvent charged into the furnace from being discharged outside the furnace, and as a result, the concentration of phosphorus in the molten iron at the end of the dephosphorization treatment can be reduced. On the other hand, in Comparative Example 2, slag (slag discharge) occurred in the dephosphorization treatment, and the phosphorus concentration in the molten iron at the end of the dephosphorization treatment could not reach the target value.

1‧‧‧轉爐型精煉爐 1‧‧‧ Converter type refining furnace

2‧‧‧頂吹式噴槍 2‧‧‧Top blow gun

3‧‧‧底吹風口 3‧‧‧ bottom air outlet

4‧‧‧流出口 4‧‧‧Exit

5‧‧‧熔鐵 5‧‧‧ molten iron

6‧‧‧脫矽熔渣 6‧‧‧Disintegration slag

8‧‧‧氧氣 8‧‧‧Oxygen

9‧‧‧底吹氣體 9‧‧‧ bottom blowing gas

11‧‧‧煙道 11‧‧‧ flue

12‧‧‧罩 12‧‧‧ Cover

13、14‧‧‧開口部 13, 14‧‧‧ openings

15‧‧‧微波熔渣位高計 15‧‧‧Microwave slag level

16‧‧‧波導管 16‧‧‧waveguide

17‧‧‧發送天線 17‧‧‧Transmission antenna

18‧‧‧接收天線 18‧‧‧ receiving antenna

Claims (10)

一種熔鐵的預備處理方法，包括：脫矽處理步驟，自頂吹式噴槍對轉爐型精煉爐內的熔鐵供給氣態氧源而對上述熔鐵進行脫矽處理；除渣步驟，將上述脫矽處理步驟中生成的熔渣的至少一部分自上述轉爐型精煉爐排出；以及脫磷處理步驟，在上述除渣步驟後，向上述轉爐型精煉爐內添加CaO系溶劑，自上述頂吹式噴槍供給氣態氧源而對殘留的熔鐵進行脫磷處理，上述熔鐵的預備處理方法的特徵在於：在上述脫矽處理中對爐內的熔渣高度進行測定，在測定出的上述熔渣高度相對於爐內的熔鐵浴面至爐口為止的爐內自由區域的高度的比率為規定的範圍的狀態下，結束上述脫矽處理，根據上述熔渣高度的測定結果，在上述脫矽處理中，對選自來自上述頂吹式噴槍的氣態氧源的供給流量、上述頂吹式噴槍的噴槍高度、來自底吹風口的攪拌用氣體的供給流量、上述爐內的熔渣的組成、起泡鎮靜材料的投入量所組成的群組中的至少1種進行調整，藉由上述調整對上述脫矽處理中的上述爐內的熔渣高度進行控制。 A preparation method for molten iron, comprising: a dislocation treatment step of supplying a molten oxygen source to a molten oxygen source in a converter type refining furnace from a top-blown spray gun to perform a deodorization treatment on the molten iron; At least a part of the slag generated in the 矽 processing step is discharged from the converter type refining furnace; and a dephosphorization treatment step, after the slag removing step, adding a CaO solvent to the converter type refining furnace, from the top blowing type lance The residual molten iron is subjected to dephosphorization treatment by supplying a gaseous oxygen source, and the molten iron preparation processing method is characterized in that the slag height in the furnace is measured in the above-described deodorization treatment, and the measured slag height is measured When the ratio of the height of the free area in the furnace from the molten iron bath surface in the furnace to the furnace opening is within a predetermined range, the above-described deodorization treatment is completed, and the above-described deodorization treatment is performed based on the measurement result of the slag height. The supply flow rate from the gaseous oxygen source from the top-blowing lance, the lance height of the top-blowing lance, the supply flow rate of the agitation gas from the bottom vent, Said furnace slag composition, the amount of the group into calm bubbling material consisting of at least one adjusted by the adjustment of the above-described silicon removal process in the in-furnace slag height control. 如申請專利範圍第1項所述的熔鐵的預備處理方法，其中上述比率的規定的範圍為0.5~0.9的範圍。 The method for preparing a molten iron according to the first aspect of the invention, wherein the predetermined range of the ratio is in a range of 0.5 to 0.9. 如申請專利範圍第1項所述的熔鐵的預備處理方法，其中以上述脫矽處理中的上述熔渣高度相對於上述爐內自由區域的高度的比率為0.5~0.9的範圍內的方式，對上述脫矽處理中的 上述爐內的熔渣高度進行控制。 The method for preparing a molten iron according to the first aspect of the invention, wherein the ratio of the height of the slag to the height of the free area in the furnace in the dislocation treatment is in a range of 0.5 to 0.9, In the above dislocation treatment The slag height in the above furnace is controlled. 如申請專利範圍第1項至第3項中任一項所述的熔鐵的預備處理方法，其中使用擬似隨機信號處理雷達方式微波距離計，將10GHz以下的頻率的微波發送至上述轉爐型精煉爐內並接收反射波，根據反射波的往返傳播時間而求出直至對象物為止的距離，在接收到的某規定的強度以上的反射波的信號中，將直至與反射波的信號相對應的對象物為止的距離大於直至爐口為止的距離且最接近上述直至爐口為止的距離的反射波的信號判定為來自熔渣表面的反射波的信號，而求出直至上述熔渣表面為止的距離，根據所求出的上述直至上述熔渣表面為止的距離來測定上述熔渣高度。 The method for preparing a molten iron according to any one of claims 1 to 3, wherein a microwave of a frequency of 10 GHz or less is sent to the above-mentioned converter type refining using a pseudo random signal processing radar type microwave distance meter The reflected wave is received in the furnace, and the distance to the object is obtained from the round-trip propagation time of the reflected wave, and the signal of the reflected wave of a predetermined intensity or more is received until the signal corresponding to the reflected wave is received. The distance from the object is larger than the distance from the furnace opening, and the signal of the reflected wave closest to the distance from the furnace opening is determined as the signal of the reflected wave from the surface of the slag, and the distance up to the surface of the slag is obtained. The slag height is measured based on the obtained distance from the surface of the slag. 如申請專利範圍第4項所述的熔鐵的預備處理方法，其中在由上述擬似隨機信號處理雷達方式微波距離計接收的反射波的信號中，將直至與反射波的信號相對應的對象物為止的距離並未自上述脫矽處理開始時發生變化而是繼續存在的反射波的信號作為雜訊而加以去除，然後判定來自上述熔渣表面的反射波的信號。 The method for preparing a molten iron according to claim 4, wherein in the signal of the reflected wave received by the pseudo-random signal processing radar type microwave distance meter, an object corresponding to the signal of the reflected wave is used. The distance until the distance is changed from the start of the above-described dislocation process, and the signal of the reflected wave that continues to exist is removed as noise, and then the signal of the reflected wave from the surface of the slag is determined. 如申請專利範圍第1項至第3項中任一項所述的熔鐵的預備處理方法，其中使用擬似隨機信號處理雷達方式微波距離計，將10GHz以下的頻率的微波發送至上述轉爐型精煉爐內並接收來自爐內的反射波，根據反射波的往返傳播時間而求出直至對象物為止的距離， 在來自存在於爐口至熔鐵浴面為止的範圍內的對象物的反射波的信號中，將直至與反射波的信號相對應的對象物為止的距離並未自上述脫矽處理開始時發生變化而是繼續存在的反射波的信號作為雜訊而加以去除，然後將與熔鐵浴面相對應的反射波的信號去除而將反射強度最高的反射波的信號判定為來自熔渣表面的反射波的信號，而求出直至上述熔渣表面為止的距離，根據所求出的上述直至上述熔渣表面為止的距離來測定上述熔渣高度。 The method for preparing a molten iron according to any one of claims 1 to 3, wherein a microwave of a frequency of 10 GHz or less is sent to the above-mentioned converter type refining using a pseudo random signal processing radar type microwave distance meter The reflected wave from the inside of the furnace is received in the furnace, and the distance up to the object is obtained from the round-trip propagation time of the reflected wave. In the signal of the reflected wave from the object in the range from the furnace opening to the molten iron bath surface, the distance up to the object corresponding to the reflected wave signal does not occur from the start of the above-described dislocation processing. The signal of the reflected wave that continues to exist is removed as noise, and then the signal of the reflected wave corresponding to the surface of the molten iron bath is removed, and the signal of the reflected wave having the highest reflection intensity is determined as the reflected wave from the surface of the slag. The signal is obtained, and the distance up to the surface of the slag is obtained, and the slag height is measured based on the obtained distance to the surface of the slag. 如申請專利範圍第1項至第3項中任一項所述的熔鐵的預備處理方法，其中在上述轉爐型精煉爐中的上一次加料的熔鐵的上述脫磷處理步驟結束後，使經上述脫磷處理的熔鐵流出，在不使上述脫磷處理中生成的爐內的熔渣排出而殘留於上述轉爐型精煉爐內的狀態下，將新的熔鐵裝入至上述轉爐型精煉爐內，對上述熔鐵實施上述脫矽處理步驟，在上述脫矽處理結束時，將爐內熔渣的鹼度設為0.8以上、1.5以下，熔鐵的溫度設為1280℃以上、1380℃以下，熔鐵的矽含量設為0.10質量%以下，在上述除渣步驟中，將上述脫矽處理步驟中生成的熔渣的30質量%以上排出至爐外，然後，對爐內的熔鐵實施上述脫磷處理步驟，在上述脫磷處理步驟結束後，使經上述脫磷處理的熔鐵流出，在不使上述脫磷處理中生成的爐內的熔渣排出而殘留於上述轉爐型精煉爐內的狀態下，將新的熔鐵裝入至上述轉爐型精煉爐內，對上述熔鐵進行預備處理。 The method for preparing a molten iron according to any one of the items 1 to 3, wherein after the step of dephosphorization of the molten iron of the last feeding in the converter type refining furnace is completed, When the molten iron in the dephosphorization treatment is discharged, the molten iron in the furnace is discharged and left in the converter type refining furnace, and a new molten iron is charged into the converter type. In the refining furnace, the above-mentioned molten iron is subjected to the above-described deodorizing treatment step, and when the above-mentioned deodorizing treatment is completed, the alkalinity of the molten slag in the furnace is set to 0.8 or more and 1.5 or less, and the temperature of the molten iron is set to 1280 ° C or more and 1380. In the above-described slag removal step, 30% by mass or more of the slag generated in the above-described deodorization step is discharged to the outside of the furnace, and then the furnace is melted. The iron is subjected to the dephosphorization treatment step, and after the dephosphorization treatment step is completed, the molten iron subjected to the dephosphorization treatment is discharged, and the molten slag in the furnace which is generated in the dephosphorization treatment is not discharged and remains in the converter type. In the state of the refining furnace, The molten iron was charged into the above-described converter type refining furnace above molten iron preliminary treatment. 如申請專利範圍第1項至第3項中任一項所述的熔鐵的預 備處理方法，其中在上述除渣步驟後的上述脫磷處理中測定爐內的熔渣高度，對選自來自上述頂吹式噴槍的氣態氧源的供給流量、上述頂吹式噴槍的噴槍高度、來自上述底吹風口的攪拌用氣體的供給流量所組成的群組中的至少1種進行調整，並以藉由上述調整而爐內的熔渣不會自爐口噴出的方式進行控制。 The preheating of the molten iron as described in any one of claims 1 to 3 a preparation method, wherein a slag height in the furnace is measured in the dephosphorization treatment after the slag removing step, a supply flow rate selected from a gaseous oxygen source from the top-blowing lance, and a lance height of the top-blowing lance At least one of the group consisting of the supply flow rate of the agitation gas from the bottom air outlet is adjusted, and the slag in the furnace is not discharged from the furnace port by the above adjustment. 如申請專利範圍第6項所述的熔鐵的預備處理方法，其中在上述轉爐型精煉爐中的上一次加料的熔鐵的上述脫磷處理步驟結束後，使經上述脫磷處理的熔鐵流出，在不使上述脫磷處理中生成的爐內的熔渣排出而殘留於上述轉爐型精煉爐內的狀態下，將新的熔鐵裝入至上述轉爐型精煉爐內，對上述熔鐵實施上述脫矽處理步驟，在上述脫矽處理結束時，將爐內熔渣的鹼度設為0.8以上、1.5以下，熔鐵的溫度設為1280℃以上、1380℃以下，熔鐵的矽含量設為0.10質量%以下，在上述除渣步驟中，將上述脫矽處理步驟中生成的熔渣的30質量%以上排出至爐外，然後，對爐內的熔鐵實施上述脫磷處理步驟，在上述脫磷處理步驟結束後，使經上述脫磷處理的熔鐵流出，在不使上述脫磷處理中生成的爐內的熔渣排出而殘留於上述轉爐型精煉爐內的狀態下，將新的熔鐵裝入至上述轉爐型精煉爐內，對上述熔鐵進行預備處理。 The method for preparing a molten iron according to claim 6, wherein after the dephosphorization treatment step of the molten iron of the last addition in the converter type refining furnace, the molten iron subjected to the dephosphorization treatment is subjected to the dephosphorization treatment In the state where the slag in the furnace which is formed in the dephosphorization treatment is not discharged and remains in the converter type refining furnace, a new molten iron is charged into the converter type refining furnace, and the molten iron is placed thereon. When the above-described deodorization treatment is completed, the alkalinity of the slag in the furnace is set to 0.8 or more and 1.5 or less, and the temperature of the molten iron is set to be 1280° C. or higher and 1380° C. or lower. In the slag removal step, 30% by mass or more of the slag generated in the above-described deodorization treatment step is discharged to the outside of the furnace, and then the dephosphorization treatment step is performed on the molten iron in the furnace. After the completion of the dephosphorization treatment step, the molten iron which has been subjected to the dephosphorization treatment is discharged, and the slag in the furnace which is formed in the dephosphorization treatment is discharged and remains in the converter type refining furnace. New molten iron is loaded into Said converter type refining furnace above molten iron preliminary treatment. 如申請專利範圍第6項所述的熔鐵的預備處理方法，其中在上述除渣步驟後的上述脫磷處理中測定爐內的熔渣高度，對選自來自上述頂吹式噴槍的氣態氧源的供給流量、上述頂吹式 噴槍的噴槍高度、來自上述底吹風口的攪拌用氣體的供給流量所組成的群組中的至少1種進行調整，並以藉由上述調整而爐內的熔渣不會自爐口噴出的方式進行控制。 The method for preparing a molten iron according to claim 6, wherein the slag height in the furnace is determined in the dephosphorization treatment after the slag removing step, and the gaseous oxygen selected from the top-blowing lance is selected Source supply flow, top blow type At least one of the group consisting of the height of the lance of the lance and the supply flow rate of the agitation gas from the bottom air outlet is adjusted, and the slag in the furnace is not ejected from the furnace by the above adjustment. Take control.
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