1223006 玖、發明說明 【發明所屬之技術領域】 本發明係關於在從高爐風口中大量吹送微粉碳（P C )的高 爐作業中，製造出安定且低矽熔鐵的技術。 【先前技術】 在以削減高爐之熔鐵製造成本，以及達延長焦炭爐壽命 功效之目的下，便有開發從高爐風口吹入大量的微粉碳， 俾降低焦炭使用量的高爐操作方法（即，供提高焦炭取代率 的高爐操作方法）。朝高爐吹送微粉碳之設備的一例，如圖 1 (a)與圖1 (b)所示。如同圖中·的槪略縱切剖圖所示，在高 爐1下半部設置斜向貫通插入朝向爐內送風用吹管（blow pip e)2側壁的微粉碳吹送用噴槍（ianc e)3，並從此微粉碳吹 送用噴槍3將微粉碳5吹出於在吹管2內流通的熱風7中， 然後再從風口 4朝高爐1爐內進行吹入。如此所吹入的微 粉碳5便在吹管2、風口 4、及風口 4前方所形成的循環區 (Raceway)6內進行燃燒，而其中一部份則未燃燒而形成碳 渣，或者煤炭中揮發成分將不完全燃燒而形成煤煙，該等 將被帶入爐內。未燃燒碳渣及煤煙雖將在爐內進行燃燒， 但是若吹入高爐內的微粉碳量較多的話，該等將未被完全 燃燒殆盡，而儲存於爐內、或形成煤塵並經由爐頂部排放 出。所以，在爲發揮微粉碳大量吹送的效果方面，便必須 達提昇微粉碳的反應效率，且提昇焦炭取代率，同時必須 確保安定的高爐操作。 但是，吹入大量微粉碳之高爐的操作，一般較容易受到 原燃料性狀或鐵渣的影響，而增加操作變動。若微粉碳吹 6 312/發明說明書(補件)/92-04/92101454 1223006 送量增加的話，將隨高爐內的礦石/焦炭比（o/c)增加而降 低熱流比（固體塡入物熱容量/氣體熱容量），爐頂排氣的帶 出顯熱（sesible heat)將增加而降低熱效率，同時在爐內的 上、中段部分，塡入物的昇溫速度將上升，且在爐下半部 中熔接帶將往上方移動，同時增加其厚度，而且將隨焦炭 塊滯留時間的增加而引起劣化，並使爐內壓力損失增加， 造成操作變動的主因。 所以，此種操作變動增加或熱效率降低的對策，便是提 昇爐熱程度俾達操作安定化。但是，結果熔鐵溫度程度將 上升且熔鐵中S i濃度將上升。此外，若微粉碳吹入量增加 的話，將隨礦石/焦炭比的增加、焦炭劣化或微粉碳未燃碳 渣的增加，將使高爐下半部爐芯部的通氣、通液性惡化而 非活性化。結果，熔渣便將流下於循環區附近，使熔渣中 的Si02被焦炭或微粉碳的C還原而產生SiO氣體，此將 被熔鐵中的C還原，使Si移至熔鐵中’導致熔鐵中的Si 濃度增加。其間的狀況，如下化學式所示： (Si〇2) + C(焦炭或 PC) = SiO(g) + CO(g)…（1)1223006 发明 Description of the invention [Technical field to which the invention belongs] The present invention relates to a technology for producing stable and low-silicon molten iron in a blast furnace operation in which a large amount of fine powder carbon (P C) is blown from a blast furnace tuyere. [Previous technology] In order to reduce the manufacturing cost of blast furnace iron melting and achieve the effect of extending the life of coke oven, there have been developed blast furnace operation methods that blow a large amount of fine powder carbon from the blast furnace tuyere to reduce the amount of coke used (ie, For improving the coke replacement rate of the blast furnace). An example of a device for blowing fine carbon toward a blast furnace is shown in Figs. 1 (a) and 1 (b). As shown in the vertical cross-sectional view of the figure, a pulverized carbon blowing spray gun (ianc e) 3 is inserted in the lower half of the blast furnace 1 and inserted obliquely into the side wall of the blow pipe 2 for blowing air in the furnace. From this fine powder carbon blowing gun 3, the fine powder carbon 5 is blown out of the hot air 7 flowing through the blow pipe 2, and then blown into the blast furnace 1 from the tuyere 4. The finely powdered carbon 5 blown in this way is burned in the circulation area 6 formed in front of the blow pipe 2, the tuyere 4, and the tuyere 4, and a part of it is not burned to form carbon slag, or the coal is volatilized. The ingredients will not burn completely to form soot, which will be brought into the furnace. Although the unburned carbon slag and soot will be burned in the furnace, if the amount of fine powder carbon blown into the blast furnace is large, these will not be completely burned and will be stored in the furnace, or coal dust will be formed and passed through the furnace. The top drains. Therefore, in order to exert the effect of mass blowing of fine powder carbon, it is necessary to improve the reaction efficiency of fine powder carbon and increase the coke replacement rate, and at the same time, it is necessary to ensure stable blast furnace operation. However, the operation of a blast furnace in which a large amount of fine carbon is blown is generally more easily affected by the properties of the original fuel or iron slag, which increases the operation variation. If the fine powder carbon blowing 6 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 increases, the heat flow ratio will decrease as the ore / coke ratio (o / c) in the blast furnace increases (heat capacity of solid infill) / Gas heat capacity), the sensible heat of the furnace top exhaust will increase and decrease the thermal efficiency. At the same time, in the upper and middle sections of the furnace, the heating rate of the injecting materials will increase, and in the lower half of the furnace, The welding zone will move upwards while increasing its thickness, and will cause deterioration with the increase of the residence time of the coke block, and increase the pressure loss in the furnace, which will be the main cause of the change in operation. Therefore, as a countermeasure for such an increase in operation variation or a decrease in thermal efficiency, it is necessary to increase the heat level of the furnace to achieve stable operation. However, as a result, the temperature of the molten iron will increase and the Si concentration in the molten iron will increase. In addition, if the amount of fine powder carbon is increased, the increase in the ore / coke ratio, the deterioration of coke, or the increase of fine powder carbon unburned carbon slag will worsen the ventilation and liquid permeability of the core of the lower half of the blast furnace. Activation. As a result, the slag will flow down near the circulation zone, and the SiO2 in the slag will be reduced by C of coke or fine powder carbon to generate SiO gas. This will be reduced by C in the molten iron, and the Si will be moved to the molten iron. The Si concentration in the molten iron increases. The situation during this period is shown in the following chemical formula: (Si〇2) + C (coke or PC) = SiO (g) + CO (g) ... (1)
Si〇(g) + [C] = [Si] + CO(g) …（2) 熔渣的Si濃度上升係指爲在高爐內還原Si02，而消耗 大量熱量。在熔鐵送出後的熔鐵爐外脫矽處理中’脫矽劑 使用量將增加，而將導致龐大的成本徒增問題。所以’爲 抑制此缺失，將高爐爐內的熔鐵s i濃度降低乃屬重要事 項0 312/發明說明書(補件)/92-04/92101454 1223006 降低高爐爐內的熔鐵s i濃度之技術已有多數提案。 習知一般方法係採行降低熔鐵溫度的方法（以下稱「習知 技術1」）。但是，此方法將引起熔渣黏性的上升（熔渣流 動性惡化）、或隨高爐內附著物的脫落等而造成熔鐵溫度急 遽下降，而產生增加操作風險的缺點。特別係當微粉碳帶 量吹入時，此影響將變大。 降低熔渣S i濃度的另一方法係有如在日本專利特開昭 5 7-2 3 7402號公報中所提案，同時吹入微粉碳與氧化鐵， 並在風口前端的高溫帶處，藉由脫矽反應：[Si]+ 2 (FeO) =(S i Ο 2) + 2 F e而氧化降低熔鐵中之S i的方法（以下稱「習知 技術2」）。而在更進一步改進習知技術2的日本專利特開 昭5 9 - 1 5 3 8 1 2號公報中，便有提案在微粉碳中混合著氧化 鐡與CaO源或MgO源物質並進行吹入，同時使依上述2 反應所產生的高活性度（a c t i v i t y) S i Ο 2迅速的由高鹼度熔 渣吸收，俾阻止再加矽反應的方法（以下稱「習知技術3」）。 再者，在日本專利特開昭610 7902號公報中，便有提案 同時吹入微粉碳與Μη礦石粉，並在風口前端的高溫帶 處，利用（Μη 0)及（FeO)而引起脫矽反應，俾氧化降低熔鐡 中之Si的方法（以下稱「習知技術4」）。但是，該等方法 中，在爲吹送氧化物方面，便需要增設礦石的粉碎步驟、 或將經粉碎者搬送至風口的搬送設備，導致熔鐵製造成本 的增加。 再者，在日本專利特開平5 - 7 8 7 1 8號公報中，在爲求利 用所吹入微粉碳中之Si02的下示式（3)〜（5): 8 312/發明說明書(補件)/92-04/92101454 1223006Si0 (g) + [C] = [Si] + CO (g)… (2) The increase in the Si concentration of the slag refers to the reduction of Si02 in the blast furnace, which consumes a large amount of heat. In the desilication treatment outside the iron melting furnace after the iron is sent out, the amount of the desilication agent used will increase, which will cause a huge cost increase problem. Therefore, in order to suppress this deficiency, it is important to reduce the concentration of si in molten iron in the blast furnace. 0 312 / Instruction for Inventory (Supplement) / 92-04 / 92101454 1223006 Techniques for reducing the concentration of si in molten iron in blast furnace have been developed. Most proposals. The conventional general method is a method for reducing the molten iron temperature (hereinafter referred to as "Knowledge Technology 1"). However, this method will cause the viscosity of the slag to rise (the slag fluidity will deteriorate), or the temperature of the molten iron will drop sharply due to the shedding of adherent materials in the blast furnace, which will lead to the disadvantage of increasing the risk of operation. This effect is particularly large when the fine carbon ribbon is blown in. Another method to reduce the S i concentration of the slag is as proposed in Japanese Patent Laid-Open No. Sho 5 7-2 3 7402, in which fine carbon and iron oxide are simultaneously blown, and at a high temperature zone at the front end of the tuyere, by Desiliconization: [Si] + 2 (FeO) = (S i 〇 2) + 2 F e and oxidation to reduce Si in molten iron (hereinafter referred to as "conventional technology 2"). In Japanese Patent Application Laid-Open No. 5 9-1 5 3 8 1 2 which is a further improvement of the conventional technology 2, there is a proposal to mix and mix rhenium oxide with a CaO source or MgO source material in fine powder carbon and blow it in. At the same time, the method for causing the high activity S i 〇 2 generated by the above 2 reactions to be quickly absorbed by the high-basicity slag and preventing the addition of the silicon reaction (hereinafter referred to as "known technology 3"). Furthermore, in Japanese Patent Laid-Open No. 610 7902, there is a proposal to blow in fine carbon and Mn ore powder at the same time, and use (Μη 0) and (FeO) to cause desiliconization at a high temperature zone at the front end of the tuyere. A method to reduce Si in the molten metal by reaction and osmium oxidation (hereinafter referred to as "known technique 4"). However, in these methods, in order to blow oxides, it is necessary to add a crushing step of ore, or a conveying device that transports the crushed person to the tuyere, resulting in an increase in the manufacturing cost of molten iron. Furthermore, in Japanese Patent Laid-Open No. 5-7 8 7 1 8, the following formulas (3) to (5): 8 312 / Invention Specification (Supplementary) for the use of Si02 blown into the fine powder carbon Pieces) / 92-04 / 92101454 1223006
Si〇2(焦炭）+ c(焦炭）= SiO(g) + CO(g)··· (3) (Si〇2) + [C] = SiO(g) + CO(g) …（4)Si〇2 (coke) + c (coke) = SiO (g) + CO (g) ... (3) (Si〇2) + [C] = SiO (g) + CO (g)… (4)
SiO(g) + [C] = [Si] + CO(g) …（5) 而抑制對熔鐵的加矽，便分別將s i 02含量較高的微粉碳、 與含量較低的微粉碳裝入分開的料箱（hopper)中，然後配 合標的熔鐵S i濃度，選擇所用微粉碳的方法（以下稱「習 知技術5」）。但是，在此方法中，因爲必須設置個別的料 箱，並調f卩塡入’因此便將徒增設備成本，並限制煤炭供 需步驟。 再者，在日本專利特開平7 - 7 0 6 1 6號公報中，便有提案 降低所製作分開的基質熔鐵Si濃度之方法，係使用Si02 含量較低於焦炭中所採用非微黏結碳的微粉碳，而降低熔 鐵Si濃度的方法（以下稱「習知技術6」）。但是，若依照 此方法的話，S i 0 2含量較低的煤炭並未必價廉，且受使用 原料的限制，在原料供需上的限制將變多，而無法實現長 期間的持續操作。 如上述，在習知技術1〜習知技術6中任一者均屬於優劣 參半，並非屬於安定的執行大量吹入微粉碳，且非屬於可 獲得綜合成本優點之高爐的低S i操作技術。在對高爐吹入 大量微粉碳的操作中，將高爐塡入原料之供需步驟未受限 制設定爲前提條件，若整體低S i熔鐵製造的高爐操作所關 聯的基本事項，便如下述。其中，下式（1)與（2)係關聯加 矽（加Si)的反應式， (Si02) + C(焦炭或 PC) 9 312/發明說明書(補件)/92-04/92101454 1223006 = SiO(g) + CO(g) …⑴SiO (g) + [C] = [Si] + CO (g)… (5) while suppressing the addition of silicon to the molten iron, the fine powder carbon with higher si 02 content and the fine powder carbon with lower content are respectively charged Put it into a separate hopper, and then select the method of fine powder carbon (hereinafter referred to as "conventional technology 5") according to the target molten iron Si concentration. However, in this method, since it is necessary to set up individual bins and adjust f ', it will increase the equipment cost and limit the steps of coal supply and demand. Furthermore, in Japanese Patent Laid-Open Publication No. 7-7076, a method has been proposed to reduce the Si concentration of the separate matrix molten iron produced by using a non-micro-bonding carbon with a lower Si02 content than that used in coke. Method for reducing the concentration of Si in molten iron (hereinafter referred to as "the conventional technology 6"). However, if this method is adopted, coal with a low S i 0 2 content is not necessarily cheap, and due to the restrictions on the use of raw materials, there will be more restrictions on the supply and demand of raw materials, and it will not be possible to achieve long-term continuous operation. As described above, any of the conventional technologies 1 to 6 is a mixed bag, not a stable low-intensity operation technology for performing a large amount of injecting fine powder carbon, and not a blast furnace that can obtain comprehensive cost advantages. In the operation of blowing a large amount of fine powder carbon into a blast furnace, setting the supply and demand steps of the blast furnace as raw materials is not limited as a prerequisite. If the overall operation of a blast furnace made of a low-Si iron melt as a whole is as follows. Among them, the following formulae (1) and (2) are related to the reaction equation of adding silicon (plus Si), (Si02) + C (coke or PC) 9 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 = SiO (g) + CO (g)… ⑴
SiO(g) + [C] = [Si] + CO(g) …（2) 下式（3): (Si〇2)+2[Fe]=[Si]+2FeO …（3) 則關聯於爐床部熔液滯留部處之還原矽（還原Si)的反應 式。 基本事項1 :降低風口前端處之高溫反應區域溫度，而控 制朝式（1)與式（2)的反應速度與化學平衡常數變小的方 向，俾降低熔鐵中S i濃度； 基本事項2 :降低熔融熔渣中Si02的活性度，而控制朝式 (1)之化學平衡常數變小方向，藉此控制朝式（2)之化學平 衡常數的方向，俾降低熔鐵中S i濃度； 基本事項3 :藉由抑制熔融熔渣靠近風口前端的高溫反應 區域，使熔渣中Si 02成分未影響式（1)的反應，並藉由抑 制Si 02氣體與熔鐵間的接觸（特別係風口前端之高溫反應 區域中的二者接觸），而降低式（2)之反應量，俾抑制對熔 鐵的加矽（加S i); 基本事項4 :藉由降低爐熱程度而施行低溫出鐵操作，而 降低式（3 )之反應速度，俾抑制還原矽（還原S i )，同時降低 式（1)之反應速度，藉此而抑制加矽。 習知，在上述基本事項1〜4項中，降低爐熱程度（特別係 降低風口前端之高溫反應區域溫度），此對降低從高爐中所 排放出熔鐡S i濃度方面乃屬有效手段，且在對利用降低爐 床部熔液滯留部處的熔鐵溫度，而抑制從熔融熔渣產生還 10 312/發明說明書(補件)/92-04/92101454 1223006 原矽（還原S i)方面亦屬有效的，所以廣泛的採用高爐低溫 操作。 但是，如前述，在降低熔鐵溫度的高爐操作中，將隨熔 渣黏性的增加或爐內附著物的脫落等現象而導致熔鐵溫度 的急遽降低，伴隨將增加操作不安定風險的缺點。此種傾 向特別在微粉碳吹入量較多的情況時，加上爐內通氣性惡 化傾向，將更爲顯著。 有鑑於斯，本發明者等便著眼於在微粉碳大量吹入的高 爐操作中，無需新設或改造特別的設備，亦無需特別使用 品質較高的高單價原料，採用依循變動的原料供需步驟， 而預先供應的既定主原料與副原料等，並藉由該等原料調 配構造的調整機構，便可不致引發在高爐低溫操作中頗容 易發生的爐內附著物脫落事故等現象，且爐內壓力損失（特 別係爐下半部的壓力損失）將不致增加，此外在爐內滴下 帶、及其下方部區域之爐芯部處的熔鐵渣下流流路亦不致 接近風口前端的高溫區域，而是儘可能的下降於爐內半徑 方向中央處，此乃屬有效的方法。 依此特別將上述基本事項3中所述及對策設定爲本發明 的課題解決重點。針對此的方法則將降低高爐熔渣黏性俾 提高流動性當作本發明的最大課題。 其次，在解決上述課題之際，就從目標爲熔鐵製造成本 最小化，並降低從燒結礦製造步驟起至高爐操作爲止的一 連串成本之觀點而言，在當燒結礦係適當的採用低氧化矽 燒結礦之情況時，便將開發適當降低上述高爐熔渣黏性的 11 312/發明說明書(補件)/92-04/92101454 1223006 技術當作課題。 【發明內容】 本發明之目的在於提供一種低矽熔鐵之製造方法，乃當 實施對高爐吹入大量微粉碳之時，可不受高爐塡入原料的 限制，並可執行低成本且安定的操作，更使用低氧化矽燒 結礦而達降低從燒結步驟起至高爐的熔鐵製造步驟爲止的 一連串成本。 緣是，爲達上述目的，本發明便提供如下述的低矽熔鐵 之製造方法。 [1] 一種低矽熔鐵之製造方法，係在將微粉碳依150kg/t-熔鐡以上進行吹送，而朝高爐吹入大量微粉碳之操作的低 矽熔鐵之製造方法中，將從高爐所排放出熔渣中的MgO含 量調整爲5 · 5〜8 · 5重量％範圍內，並將熔鐵之s i濃度控制 在0.3重量％以下。 [2] 在[1]所述低矽熔鐵之製造方法中，係依147(rc以上 的出鐵溫度操作著高爐。 [3] 在[1]或[2]所述低矽熔鐵之製造方法中，係依 2 7 Okg/t-熔鐵以上的熔渣比操作著高爐。 [4] 在[Π至[3]中任一項所述低矽熔鐵之製造方法中，係 在上述熔渣中的C a 0 (重量％ ) / S i 02 (重量％)爲1 · 2〜1 · 3範圍 內，且該熔渣中的A12 Ο3濃度爲1 3〜1 6重量％範圍內操作 著高爐。 [5 ] —種低砂熔鐵之製造方法，係在將微粉碳依〗5 〇 k g /1 _ 熔鐵以上進行吹送’而朝高爐吹入大量微粉碳之操作的低 12 312/發明說明書(補件)/92-04/92101454 1223006 矽熔鐵之製造方法中，塡入燒結礦，該燒結物係佔除了從 爐頂所塡入焦炭之外的塡入物的70重量％以上，且Si〇2 含量4 · 5重量％以下’ M g Ο含量1 · 3重量％以下；然後，藉 由塡入MgO源副原料，而將從高爐所排放出熔渣中的Mg〇 含星S周整爲5.5〜8.5重量％範圍內。 [6]在[5]所述低矽熔鐵之製造方法中，其中，上述低石夕 熔鐵之S i濃度係控制在〇 . 3 0重量％以下。 【實施方式】 本發明者等在高微粉碳吹送比（高PCR)條件下的高爐操 作（高P C R高爐操作）中，以維持所變動原燃料的供需條件 及原燃料的低成本’並維持設備費等低成本爲前提條件， 首先針對使高爐熔渣流動性變佳的高爐熔渣成分組成之調 整進行探討。 在高爐中所產生熔渣成分組成係依存於所使用主原料 及副原料各種類之熔渣化成分含量、及焦炭與微粉碳製造 用煤炭種類別熔渣化成分含量及其調配構造等而進行變 化。高爐熔渣的黏性係依存於上述熔渣的成分組成而變 化，且熔渣溫度將依存於熔鐵溫度而產生變化。 高爐熔渣的主要構成成分係由Si02、CaO、MgO及Al2〇3 等四種成分所構成。其中，Si02及CaO含量乃因爲熔渣鹼 度（CaO重量％/Si02重量％)屬於熔鐵成分中S濃度的重要 決定因素之一，因此將受到此鹼度設定値的限制，所以在 分開獨立設定Si02與CaO含量方面頗爲困難。故，未必 可適當的將Si 02與CaO含量設定爲熔渣黏性的調整因 13 312/發明說明書(補件)/92-04/92101454 子。因爲熔渣的Al2〇3含量主要以Al2〇3爲主，並含於焦 炭中的灰分或礦石中，因此將隨原燃料供需平衡而變動。 譬如，近年反應高品質鐵礦石的枯竭化傾向，ai2〇3含量 較高之所謂高氧化鋁鐵礦石將增加。其中，高氧化鋁鐵礦 石的單價具有廉價的優點。所以，將熔渣中的Al2〇3含量 限制於習知水準以下並非對策，同時在鐵礦石的原料供需 步驟上將產生困難。 相對於此，高爐熔渣中M g 0成分，在習知技術中，其機 能爲熔渣的黏性調整。但是，熔渣中MgO含量的設定，在 習知技術中，將MgO源副原料的MgO-Si02系蛇紋岩、或 M gO-CaO系白雲石，除依利用固有高爐操作條件而所決定 的標的上限値以下之方式，並依熔渣中MgO含量成爲必要 最小極限値之方式，配合著此時的原料調配率，在塡入高 爐時進行調整。 所以，本發明者等便針對隨熔渣中MgO含量的上升，而 對熔渣黏性降低與熔鐵中S i濃度降低的作用、功效進行探 討。 以下，針對實用高爐的操作數據，採用圖2〜圖4進行說 明。 圖2所示爲熔渣之MgO含量與熔渣比間的關係，得知隨 M g 0含量的增加，熔渣比將減少。 圖3所示係熔渣之MgO含量與熔鐵Si含量間的關係， 隨MgO含量的增加，熔鐵Si含量將降低，且若MgO含量 達到7重量％程度的話，便推定熔鐵S i含量存在極小値。 14 312/發明說明書(補件)/92-04/92101454 1223006 圖4所示係熔渣之MgO含量相對於該熔渣黏度計算値間 之關係，隨MgO含量的增加，熔渣黏度將降低。在同圖中， 熔渣黏度的不均造成高爐間之主原料構成差的主因。 由上述得知下述： 1 .利用提高熔融熔渣中之M g Ο濃度，而降低熔渣的黏 性。結果，高爐下半部的滴下帶、及其下方部位的爐芯部 處之熔融熔渣下流流路，便可避免接近風口前方所形成循 環區附近之高溫反應區域側，而可垂直落下於垂直下方。 結果，便將抑制上述式（1)與式（2)的反應，而可抑制對熔 鐵的加矽。 2.藉由提高熔融熔渣中之MgO濃度，而提高循環區附近 之高溫反應區域中的Mg氣體蒸氣壓，而降低上述式（2)反 應中的SiO氣體分壓，俾降低SiO氣體的活性度，藉此而 抑制式（2)之反應，並抑制隨熔渣中Si02的還原而使Si朝 熔鐡中的移動，俾抑制熔鐵中S i濃度的上升。 3 ·除上述1與2項之外，更藉由執行高爐的適當低溫操 作，便可在安定的操作下，製造出更低S i熔鐵。 4 .習知雖認爲隨熔渣比的增加而爐下半部壓力損失將增 加’但是’本發明本次以高爐爐內整體通氣性視爲表示指 數’且將根據從風口上方1 · 5 m位置起至爐頂間之爐內壓 力損失的通氣性，轉換爲指數（-)表示，並針對熔渣比與表 示該爐內通氣性之指數（-)間的關係進行調查，結果得知若 熔渣中MgO含量提高至5.5〜8.5重量％範圍內爲止的話， 即便在將微粉碳依1 5 0 k g /1 -熔鐵以上進行吹入的高爐操作 15 312/發明說明書(補件)/92-04/92101454 1223006 中’若將出鐵溫度保持於n48以上，並將熔渣比設定在 3 0 Ok g/t-溶鐵以下的話，便不致使爐內通氣性惡化，並可 進行安定的低砂操作。 本發明乃根據上述見解而形成者。 本發明的低矽熔鐵之製造方法，係在將微粉碳依 15 Okg/t-熔鐵以上進行吹送，而朝高爐吹入大量微粉碳之 操作的低砂熔鐡之製造方法中，其特徵在於：將從高爐所排 放出熔澄中之MgO含量調整爲5.5〜8.5重量％範圍內，並 將熔鐵S i濃度抑制至〇 . 3重量％以下。 圖1所示係高爐中的微粉碳吹送設備，並依下述方式執 行本發明的方法。從斜向貫通插入於高爐1風口 4部上所 裝設吹管2中而所安裝之微粉碳吹送用噴槍3中，將微粉 碳依150kg/t-熔鐵以上，與熱風7 —齊吹入於高爐1內， 而製造熔鐵。在此高爐操作中，塡入原料係依從出鐵口 8 所排放出高爐熔渣成分組成內，MgO含量在5.5〜8.5重量 %範圍內之方式，於考慮塡入主原料與副原料中之熔渣化 成分組成之情況下，決定此塡入量的配方。此外，爐熱程 度並非採用習知微粉碳比150kg/t-熔鐡以上之高爐操作中 所使用的高熱程度操作、或者低Si熔鐡製造操作中所採用 的低溫出鐵操作。相關其他的高爐操作條件並無特別注意。 相關塡入原料與塡入焦炭的調配率，係調整爲在高爐熔 渣的成分組成內MgO = 5.5〜8.5重量％，若使爐熱程度非爲 低溫操作範圍（譬如，出鐵溫度1 4 8 0°C以上）的話便可，並 無特別的限制。但是，若依照下述條件進行的話，對降低 16 312/發明說明書(補件)/92-04/92101454 1223006 從燒結礦製造步驟起至高爐操作爲止間的一連串步驟熔鐵 成本方面將更有助益。而且，可將高爐中之礦石還原性保 持於良好狀態，同時降低高爐熔渣比（kg·熔渣/t-熔鐵），對 高P C R高爐操作的安定化頗具功效。即，採用含量爲除了 塡入焦炭之外的塡入物之70重量％以上，Si〇2 S 4.5重量％ 且M g Ο ^ 1 . 3重量％的燒結礦，並爲求將高爐熔渣之M g Ο 含量調整爲5.5〜8.5重量％範圍內，而適當的塡入MgO源 副原料。在此，M g Ο源副原料係適當的採用蛇紋岩或白雲 母等。 在上述的高爐操作中，依可獲得低矽熔鐵之方式（譬如熔 鐡S i濃度在0.3 0重量％以下）’適當的調整爐熱程度。此 情況下，若調整爲熔渣之Mg 0 = 5.5〜8.5重量％的話，即便 高爐熔渣比在270kg/t-熔鐵以上亦可，或在30〇kg/t-熔鐵 以下的話亦無妨。 另外，在本發明的任何情況下，最好將高爐熔渣中的 CaO(重量％)/3丨02(重量％)(鹼度）調整在1·2〜1.3範圍內，且 將Α 12 03濃度調整在13〜16重量％範圍內，進行高爐的操 作。 藉由將熔渣鹼度調整爲1.2〜1.3範圍內，便可將熔鐵的S 含量安定的設定於既定目標値以下。此外，可大量採用前 述近年有增加趨勢之A 12 0 3含量較高的所謂氧化鋁鐵礦石 (譬如：A 12 Ο 3 2 3 · 0重量％)的燒結礦，當作塡入原料，對鐵 礦石原料供需步驟上的限制消除具有效果，同時具有降低 原料成本之功效。 17 312/發明說明書(補件)/92-04/92101454 1223006 藉由採取上述實施形態，在高爐操作狀態與爐內反應等 之中將發現下述特徵現象。即，熔渣成分組成中，特別係 因爲將MgO濃度設定爲較高於平常操作狀況的5.5〜8 .5重 量％範圍內，因此降低熔渣的黏性，同時提高風口前端附 近之高溫反應區域的Mg蒸氣分壓。藉由熔渣黏性的降 低，而改善爐芯部的通液性，使熔融熔渣不致通過風口前 端附近之高溫反應區域的循環區附近，而直接流下於爐芯 部，因此便將抑制式（1)所示（Si 02)隨微粉碳或焦炭的還原 反應，而抑制產生SiO氣體。此外，因爲藉由此區域中的 Mg蒸氣分壓之上升，SiO氣體活性度將降低，因此便將抑 制式（2)所示SiO氣體隨熔鐵中C的還原反應，而抑制熔鐵 中S i濃度的上升。如此便可將熔鐵之S i濃度抑制到0.3 重量％以下。另外，如上述，因爲已改善爐芯部的通液性， 因此即便熔渣量的上限將容許至3 00kg/t-熔鐵，亦仍可確 保操作的安定性。 藉由將Al2〇3含量調整在13〜16重量％範圍內，便如上 述’將意味著無須特定鐵礦石種類或焦炭用原料碳種類， 除可對所使用原燃料賦予自由度之外，亦意味著在熔渣黏 性未上升的範圍內，可更簡單的執行高爐操作。 如此的話，藉由本發明的高爐操作方法，即便從風口吹 送出大量微粉碳，亦仍可安定的執行熔鐵之低矽操作。 圖5所示係朝高爐內吹送微粉碳方法的另一例剖視圖。 圖6係圖5之側視圖。 在圖5與圖6中，3係插入於風口 4所連接吹管2內的 18 312/發明說明書(補件)/92-04/92101454 1223006 二根微粉碳吹送用噴槍。噴槍3係依前端朝向風口 4側之 方式，且依各噴槍3中心軸線（1)未與吹管2軸線（L)交叉之 方式，並相對於吹管2中心軸線（〇)呈軸對稱之方式進行配 置。 微粉碳係與來自二根噴槍3，的載氣（carrier gas)，共同依 1 5 m/sec程度的流速朝吹管2內吹送，但是因爲二根噴槍3 前端，並非在同一直線上相對向著，而是採軸對稱位置配 置方式，因此微粉碳將可不致相互干涉的吹向吹管2內， 並迅速的在吹管2內進行擴散。同時，因爲微粉碳將在吹 管2內一邊進行旋轉一邊朝風口 4側移動，因此在與熱風 中之氧間的接觸效率將更佳，所以將提昇微粉碳的燃燒效 率。載氣係由如：氮氣、空氣、氧氣、CO、C02氣體中至少 其中一種所構成。 利用實施例更詳盡的說明本發明。 相關本發明的低矽熔鐵之製造方法範圍內的實施例、及 範圍外的比較例進行測試。實施例的高爐操作方法及條件 係在本發明實施形態中，依據上述方法及條件而實施。表 1〜2所示係測試結果，表3、4所示係微粉碳及燒結礦的成 分組成。 19 312/發明說明書(補件)/92-04/92101454 1223006 比較例4 200 00 卜 1 326 〇 14.6 1.27 260 1500 0.45 卜 r-H 〇〇 〇 0.025 X X < 比較例3 150 卜 卜 1 366 〇 14.6 1.27 270 1500 0.32 卜 τ-Η 〇〇 〇 0.025 X <] 比較例2 120 1 390 Ο 14.6 1.27 280 1480 0.23 ν〇 r-H 〇〇 〇 0.033 律 < X 比較例1 120 1 390 ο 14.6 1.27 280 1500 0.30 寸 τ—^ 0.8 0.028 壊 〇 〇 微粉碳吹入比（kg/t-熔鐵） 燒結礦-A 燒結礦-B 焦炭 o bO ro 〇 <N < rs 〇 fH 00 o cd u 熔澄比（kg/t-熔鐵） 出鐵溫度（°C ) 熔鐵Si濃度（％) 高爐整體通氣性（-) 焦炭取代率（％) 熔鐵S濃度（％) 熔渣導管產生溢流 高爐操作安定性 熔渣黏性評估 塡入原料配方 熔渣成分 高爐操作條件 高爐操作試驗SiO (g) + [C] = [Si] + CO (g)… (2) The following formula (3): (Si〇2) +2 [Fe] = [Si] + 2FeO… (3) is related to The reaction formula of reduced silicon (reduced Si) in the molten metal stagnation portion of the hearth. Basic item 1: Reduce the temperature of the high-temperature reaction area at the front end of the tuyere, and control the reaction speed and chemical equilibrium constant of formula (1) and formula (2) to decrease, so as to reduce the Si concentration in the molten iron; Basic item 2 : Reduce the activity of Si02 in the molten slag, and control the direction of the chemical equilibrium constant of formula (1) to decrease, thereby controlling the direction of the chemical equilibrium constant of formula (2), and reduce the Si concentration in the molten iron; Basic matter 3: By suppressing the high temperature reaction zone of the molten slag close to the front end of the tuyere, the Si 02 component in the slag does not affect the reaction of formula (1), and by suppressing the contact between the Si 02 gas and the molten iron (particularly The high temperature reaction area at the front end of the tuyere is in contact with each other), and the reaction amount of formula (2) is reduced, and the addition of silicon to the molten iron (plus Si) is suppressed; Basic item 4: Low temperature by reducing the degree of furnace heat The tapping operation reduces the reaction speed of the formula (3), and suppresses the reduction of silicon (reduction Si), while reducing the reaction speed of the formula (1), thereby suppressing the addition of silicon. It is known that in the above-mentioned basic items 1 to 4, reducing the degree of furnace heat (especially reducing the temperature of the high-temperature reaction zone at the front end of the tuyere) is an effective means to reduce the concentration of molten sulphur emitted from the blast furnace. In addition, in terms of reducing the molten iron temperature in the molten metal stagnation portion of the hearth and suppressing the generation of molten slag, 10 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 Original silicon (reduction Si) It is also effective, so blast furnace low temperature operation is widely used. However, as mentioned above, in the blast furnace operation that lowers the molten iron temperature, the molten iron temperature will decrease sharply with the increase of the viscosity of the slag or the dropping of the adherends in the furnace, which will increase the risk of unstable operation. . This tendency is particularly significant when the amount of fine powder carbon is blown in, and the tendency of the ventilation in the furnace is deteriorated. In view of this, the inventors have focused on the operation of blast furnaces in which a large amount of fine powder carbon is blown in, without the need to newly set up or modify special equipment, and without the need to use high-quality high-priced raw materials. The pre-supplied main raw materials and auxiliary raw materials, etc., and the adjustment mechanism of the raw material deployment structure can not cause the phenomenon of falling off of the adherend in the furnace, which is easy to occur in the low temperature operation of the blast furnace, and the pressure in the furnace. The loss (especially the pressure loss in the lower half of the furnace) will not increase. In addition, the molten iron slag downstream flow path in the furnace drip zone and its lower core area will not approach the high temperature area at the front end of the tuyere, and It is an effective method to lower it to the center in the radial direction of the furnace as much as possible. Accordingly, the above-mentioned basic matter 3 and the countermeasures are specifically set as the problems to be solved by the present invention. For this method, reducing the viscosity of the blast furnace slag and improving the fluidity are regarded as the biggest problems of the present invention. Secondly, in order to solve the above-mentioned problems, from the viewpoint of minimizing the manufacturing cost of molten iron and reducing a series of costs from the sintering ore manufacturing step to the operation of the blast furnace, when the sintering ore system appropriately adopts low oxidation In the case of silicon sintered ore, the development of 11 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 technology for appropriately reducing the viscosity of the above-mentioned blast furnace slag is a task. [Summary of the Invention] The object of the present invention is to provide a method for manufacturing a low-silicon molten iron, which can be implemented without blowing the raw materials into the blast furnace, and can perform low-cost and stable operations when a large amount of fine powder carbon is blown into the blast furnace. In addition, low-oxidation silicon sintered ore is used to reduce a series of costs from the sintering step to the molten iron manufacturing step of the blast furnace. The reason is that in order to achieve the above object, the present invention provides a method for manufacturing a low-silicon molten iron as described below. [1] A manufacturing method of low-silicon molten iron, in which a method of manufacturing low-silicon molten iron in which fine powder carbon is blown at 150 kg / t-melt or higher and a large amount of fine powder carbon is blown into a blast furnace, The content of MgO in the slag discharged from the blast furnace is adjusted to be within a range of 5 · 5 to 8 · 5% by weight, and the si concentration of the molten iron is controlled to 0.3% by weight or less. [2] In the manufacturing method of the low silicon molten iron described in [1], the blast furnace is operated at a tapping temperature of 147 (rc or higher. [3] In the low silicon molten iron described in [1] or [2], In the manufacturing method, the blast furnace is operated in accordance with a slag ratio of 27 Okg / t-iron or more. [4] In the manufacturing method of the low-silicon molten iron described in any one of [Π to [3], The Ca 0 (wt%) / Si 02 (wt%) in the slag is in the range of 1 · 2 ~ 1 · 3, and the concentration of A12 Ο3 in the slag is in the range of 1 ~ 16% by weight The blast furnace is in operation. [5] —A method for manufacturing low-sand molten iron, which is based on the operation of blowing fine powder carbon at 50 kg / 1 _ above the molten iron and blowing a large amount of fine powder carbon into the blast furnace. 12 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 In the method for manufacturing silicon fused iron, sintered ore is charged, and the sintered material accounts for 70% by weight of the input except the coke input from the furnace roof. Above, and the content of SiO2 is 4 · 5% by weight or less, and the content of Mg 〇 is 1 · 3% by weight or less. Then, the MgO content in the slag discharged from the blast furnace is charged by injecting the MgO source by-products. Star S week is 5.5 ~ 8.5 weight [6] In the method for manufacturing a low-silicon molten iron described in [5], the S i concentration of the low-rock fused iron is controlled to 0.30% by weight or less. [Embodiment] This The inventors, in a blast furnace operation (high PCR blast furnace operation) under high carbon powder blowing ratio (high PCR) conditions, maintain the low supply and demand conditions of the raw fuel and the low cost of the raw fuel, and maintain low costs such as equipment costs. The precondition is to first discuss the adjustment of the composition of the blast furnace slag composition that makes the blast furnace slag fluidity better. The composition of the slag composition generated in the blast furnace depends on various types of slag-forming components used in the main and auxiliary raw materials. Content, as well as the content of slagification components and the blending structure of coal types used in the production of coke and fine powder carbon. The viscosity of the blast furnace slag varies depending on the composition of the slag, and the temperature of the slag will depend on It varies with the temperature of the molten iron. The main components of the blast furnace slag are composed of four components: Si02, CaO, MgO, and Al203. Among them, the content of Si02 and CaO is due to the basicity of the slag (CaO weight% / S (i02% by weight) is one of the important determinants of the S concentration in the molten iron component, so it will be limited by this basicity setting 値, so it is difficult to independently set the content of Si02 and CaO separately. Therefore, it may not be appropriate to The content of Si 02 and CaO is set to adjust the viscosity of the slag. 13 312 / Instruction Manual (Supplement) / 92-04 / 92101454. Because the Al203 content of the slag is mainly Al203 and is contained in The ash or ore in coke will therefore change with the supply and demand balance of raw fuel. For example, in recent years, in response to the depletion tendency of high-quality iron ore, so-called high-alumina iron ore with a higher ai203 content will increase. Among them, the unit price of high alumina iron ore has the advantage of being cheap. Therefore, limiting the Al203 content in the slag to below the conventional level is not a countermeasure, and it will cause difficulties in the supply and demand of iron ore raw materials. In contrast, in the conventional technology, the function of the M g 0 component in the blast furnace slag is to adjust the viscosity of the slag. However, in the conventional technology, the MgO content in the slag is set by using MgO-Si02 series serpentine or M gO-CaO series dolomite as the auxiliary raw material of the MgO source. The method with the upper limit 値 and the method in which the content of MgO in the slag becomes the necessary minimum limit ， is adjusted with the mixing ratio of the raw materials at this time when it is poured into the blast furnace. Therefore, the present inventors have discussed the effects and efficacy of the decrease in the viscosity of the slag and the decrease in the Si concentration in the molten iron as the content of MgO in the slag increases. Hereinafter, operation data of a practical blast furnace will be described with reference to FIGS. 2 to 4. Figure 2 shows the relationship between the MgO content of the slag and the slag ratio. It is learned that as the M g 0 content increases, the slag ratio will decrease. The relationship between the MgO content of the slag shown in Figure 3 and the Si content of the molten iron. As the MgO content increases, the Si content of the molten iron will decrease, and if the MgO content reaches about 7% by weight, the Si content of the molten iron is estimated. There is minimal 値. 14 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 The relationship between the MgO content of the slag shown in Figure 4 and the slag viscosity is calculated. As the MgO content increases, the slag viscosity will decrease. In the same figure, the main cause of the poor composition of the main raw materials in the blast furnace is caused by the uneven viscosity of the slag. From the above, the following are known: 1. The viscosity of the slag is reduced by increasing the concentration of M g 0 in the molten slag. As a result, the drip zone in the lower half of the blast furnace and the molten slag downstream flow path at the core portion of the blast furnace can be prevented from approaching the side of the high-temperature reaction area near the circulation zone formed in front of the tuyere, and can fall vertically to the vertical Below. As a result, the reaction of the above formulae (1) and (2) is suppressed, and the addition of silicon to the molten iron can be suppressed. 2. By increasing the MgO concentration in the molten slag and increasing the vapor pressure of Mg gas in the high-temperature reaction zone near the circulation zone, the partial pressure of SiO gas in the reaction of the above formula (2) is reduced, and the activity of SiO gas is reduced. In this way, the reaction of the formula (2) is suppressed, and the movement of Si into the molten iron with the reduction of Si02 in the slag is suppressed, and the increase in the Si concentration in the molten iron is suppressed. 3. In addition to items 1 and 2 above, by performing appropriate low-temperature operation of the blast furnace, a lower Si molten iron can be manufactured under stable operation. 4. Although it is known that the pressure loss in the lower half of the furnace will increase with the increase of the slag ratio, but the present invention considers the overall ventilation in the blast furnace as an index, and will be based on the temperature from the top of the tuyere. The permeability of the pressure loss in the furnace from the m position to the top of the furnace was converted into an index (-), and the relationship between the slag ratio and the index (-) indicating the gas permeability in the furnace was investigated, and the results were obtained. If the MgO content in the slag is increased to a range of 5.5 to 8.5% by weight, even in a blast furnace operation in which fine powder carbon is blown in at 150 kg / 1-molten iron or more 15 312 / Invention Manual (Supplement) / 92-04 / 92101454 1223006 'If the tapping temperature is maintained above n48 and the slag ratio is set below 30 Ok g / t- molten iron, it will not cause deterioration of the air permeability in the furnace and stability can be achieved. Low sand operation. This invention was made based on the said knowledge. The method for manufacturing a low-silicon molten iron of the present invention is characterized in that a method for manufacturing a low-sand smelting corundum that blows fine powder carbon at 15 Okg / t- molten iron or more and blows a large amount of fine powder carbon into a blast furnace. The reason is that the content of MgO in the melt discharged from the blast furnace is adjusted to be within a range of 5.5 to 8.5% by weight, and the concentration of the molten iron Si is suppressed to 0.3% by weight or less. The fine powder carbon blowing equipment in the blast furnace shown in Fig. 1 performs the method of the present invention in the following manner. From the obliquely inserted fine-powder carbon blowing lance 3 inserted into the blowpipe 2 installed in the 4 air outlets of the blast furnace 1, the fine-powder carbon is blown into the hot air 7 at 150kg / t- molten iron or more. Inside the blast furnace 1 to produce molten iron. In this blast furnace operation, the inflow raw materials are based on the composition of the blast furnace slag discharged from the tap hole 8 and the MgO content is in the range of 5.5 to 8.5% by weight. In the case of slagging component composition, the formula for determining the amount of this infusion is determined. In addition, the furnace heating degree is not the high-temperature operation used in the conventional blast furnace operation with a fine powder carbon ratio of 150 kg / t-smelting or higher, or the low-temperature tapping operation used in the low-Si melting furnace manufacturing operation. No special attention was paid to other blast furnace operating conditions. The blending ratio of the injecting raw materials and injecting coke is adjusted to MgO = 5.5 to 8.5% by weight in the composition of the blast furnace slag. If the furnace heat level is not a low temperature operation range (for example, the tapping temperature 1 4 8 0 ° C or higher) is not necessary. However, if the following conditions are followed, it will be more helpful to reduce the cost of molten iron in a series of steps from the sinter ore manufacturing step to the blast furnace operation in accordance with 16 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 beneficial. In addition, it can keep the ore reduction in the blast furnace in a good state, and reduce the blast furnace slag ratio (kg · slag / t-fused iron), which is effective for the stabilization of high PC C blast furnace operation. That is, a sintered ore having a content of 70% by weight or more of the injecting material other than coke intrusion, Si0 2 S 4.5% by weight, and M g 0 ^ 1.3% by weight is used. The content of M g 〇 is adjusted to be in the range of 5.5 to 8.5% by weight, and the MgO source and side raw materials are appropriately incorporated. Here, as the M g 0 source auxiliary material, serpentine or muscovite is suitably used. In the above-mentioned blast furnace operation, in order to obtain a low-silicon molten iron (for example, the concentration of fused Si is 0.30% by weight or less) ', the degree of furnace heat is appropriately adjusted. In this case, if the Mg 0 of the slag is adjusted to 5.5 to 8.5% by weight, even if the blast furnace slag ratio is 270 kg / t- molten iron or more, or if it is 30 kg / t- molten iron or less . In addition, in any case of the present invention, it is preferable to adjust CaO (wt%) / 3o02 (wt%) (basicity) in the blast furnace slag to be within a range of 1.2 to 1.3, and to adjust A 12 03 The concentration was adjusted in the range of 13 to 16% by weight, and the operation of the blast furnace was performed. By adjusting the basicity of the slag to be within the range of 1.2 to 1.3, the S content of the molten iron can be stably set below a predetermined target value. In addition, a large amount of sintered ore, such as A 12 0 3 2 · 0% by weight, which is a relatively high content of A 12 0 3 which has been increasing in recent years, can be used as a raw material. Elimination of restrictions on the supply and demand steps of iron ore raw materials has the effect, and has the effect of reducing the cost of raw materials. 17 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 By adopting the above-mentioned embodiment, the following characteristic phenomenon will be found among the blast furnace operation state and the reaction in the furnace. That is, in the slag composition, the MgO concentration is set to a range of 5.5 to 8.5% by weight, which is higher than normal operating conditions. Therefore, the viscosity of the slag is reduced, and the high-temperature reaction area near the front end of the tuyere is improved. Mg vapor partial pressure. By reducing the viscosity of the slag, the liquid permeability of the furnace core portion is improved, so that the molten slag does not pass through the vicinity of the circulation zone of the high-temperature reaction area near the front end of the tuyere, but directly flows down the furnace core portion. (Si 02) shown in (1) suppresses the generation of SiO gas with the reduction reaction of fine carbon or coke. In addition, because the Mg vapor partial pressure in this region increases, the activity of SiO gas will decrease, so the reduction reaction of SiO gas with C in molten iron will be suppressed, and S in molten iron will be suppressed. Increase in i concentration. In this way, the Si concentration of the molten iron can be suppressed to 0.3% by weight or less. In addition, as described above, since the liquid permeability of the core portion has been improved, even if the upper limit of the amount of slag is allowed to 300 kg / t-iron, the stability of the operation can be ensured. By adjusting the Al2O3 content within the range of 13 to 16% by weight, the above-mentioned 'will mean that there is no need to specify the type of iron ore or the type of raw material carbon for coke. In addition to giving freedom to the raw fuel used, It also means that the blast furnace operation can be performed more easily in the range where the viscosity of the slag does not increase. In this way, with the blast furnace operation method of the present invention, even if a large amount of fine powder carbon is blown from the tuyere, the low silicon operation of molten iron can be stably performed. Fig. 5 is a sectional view showing another example of a method for blowing fine powder carbon into a blast furnace. FIG. 6 is a side view of FIG. 5. In Figs. 5 and 6, 3 are two 18 312 / Invention Instructions (Supplements) / 92-04 / 92101454 1223006 inserted into the blow tube 2 connected to the tuyere 4 two fine powder carbon spray guns. The spray gun 3 is performed in such a manner that the front end faces the air outlet 4 side, and the center axis (1) of each spray gun 3 does not cross the axis 2 (L) of the blow pipe, and is performed in an axially symmetrical manner with respect to the center axis (0) of the blow pipe 2. Configuration. The fine powder carbon and the carrier gas from the two spray guns 3 are blown into the blow pipe 2 at a flow rate of about 15 m / sec, but because the front ends of the two spray guns 3 are not opposed to each other on the same straight line, Instead, it is arranged in an axially symmetrical position, so the fine powder carbon can be blown into the blow pipe 2 without interfering with each other, and quickly diffused in the blow pipe 2. At the same time, because the fine powder carbon will move toward the tuyere 4 while rotating in the blow pipe 2, the contact efficiency with the oxygen in the hot air will be better, so the combustion efficiency of the fine powder carbon will be improved. The carrier gas is composed of at least one of nitrogen, air, oxygen, CO, and CO2 gas. The present invention will be explained in more detail using examples. The examples related to the manufacturing method of the low-silicon molten iron of the present invention and the comparative examples outside the range were tested. The method and conditions for operating a blast furnace in the examples are implemented in accordance with the above methods and conditions in the embodiment of the present invention. The test results are shown in Tables 1 and 2. The composition of the fine powder carbon and sintered ore shown in Tables 3 and 4. 19 312 / Specification of the Invention (Supplement) / 92-04 / 92101454 1223006 Comparative Example 4 200 00 1 1 326 0 14.6 1.27 260 1500 0.45 1 rH 〇〇〇0.025 XX < Comparative Example 3 150 1 1 366 0 14.6 1.27 270 1500 0.32 τ-Η 〇〇〇0.025 X <] Comparative Example 2 120 1 390 〇 14.6 1.27 280 1480 0.23 ν〇rH 〇〇〇0.033 Law &X; Comparative Example 1 120 1 390 ο 14.6 1.27 280 1500 0.30 Inch τ— ^ 0.8 0.028 壊 〇〇 Fine powder carbon blowing ratio (kg / t- molten iron) Sinter-A Sinter-B Coke o bO ro 〇 < N < rs 〇fH 00 o cd u Melting ratio (Kg / t-melting iron) Iron tapping temperature (° C) Si concentration in molten iron (%) Overall blast furnace permeability (-) Coke substitution rate (%) S concentration in molten iron (%) Slag duct overflow overflow blast furnace operation Stability evaluation of slag viscosity
0(N 1223006 實施例9 CS1 1 § g CO 寸 οό r—Η υη i 1 1 1.27 1 ΟΟ CS1 1 1504 I 0.19 寸· 1 < 〇 0.028 摧 〇 ◎ 實施例8 ν〇 1 03 r—H m c<\ oo 14*3」 A ι—Η m οο CS1 1 1505 I 0.23 1 寸· Γ On 〇 0.025 壊 〇 ◎ 實施例7 〇 Csl 1 CN (N CO VO τ—Η ν〇 r—Η r—< νο \ο C0 1 1481 I 丨 〇·19 1 寸· ι.....! OO ci 0.031 壊 〇 ◎ 實施例6 异 CN 1 〇 t—H CO 寸 oo 1 15.0 1 r—Η ο 1 1503 I 1 0.26 1 VO τ—Η OO CD 1 0.031 1 摧 〇 ◎ 實施例5 〇 r—Η 1 〇〇 m CO VO 1 1 < r Η 1 1·27 1 1 1501 1 1 0.27 1 寸· f 'i OO o 1 0.029 1 摧 〇 〇 實施例4 Ο 1 v〇 oo i—4 m v〇 oo τ—Η ν〇 τ < ^ < C0 1 1497 1 1 0.27 1 v〇 r—Η oo o 0.036 1 壊 〇 ◎ |實施例3| s r—Η 1 ΙΟ oo CO CO vd 1 14.8 1 ▼Η Γ ΟΟ CSI 1508 1 0.22 1 寸· τ—Η oo o 1 0.023 1 摧 〇 〇 實施例2 Ο Οί 1 v〇 r<j cn csi oo 1 14.3 1 I ία 1 οο οο CSI 1 1503 1 1 0.23 1 r—ί oo o 1 0.025 1 摧 〇 ◎ 實施例1 泛 t i 1 CO V〇 un 1 14.7 1 ι " 1 ν〇 ΟΝ CN 1 1496 1 1 0.24 1 τ i oo CD 1 0.031 1 壊 〇 〇 微粉碳吹入比(kg/t-熔鐵） 燒結礦-A 燒結礦-B 焦炭 Mg0(%) Α12〇3(%) CaO%/Si〇2% 熔渣比(kg/t-熔鐵） 出鐵溫度(°C) 熔鐵Si濃度(％) 高爐整體通氣性(-) 焦炭取代率2) (%) 熔鐵s濃度(％) 熔渣導管產生溢流 高爐操作安定性 熔渣黏性評估 塡入原料 配方 熔渣成分 高爐 操作 條件 高爐 操作 試驗 l(N寸 SH0ICNJ6/s-CNI6/ff}®)_g>縮盔總/(ΝΙε 1223006 ττ (％¥«) O Csl m 00 1 < ν/Ί 〇〇 r- v〇 〇 OO 寸 ο 2 1.68 cn 00 ν·_Η E VO 00 m r—Η 寸 寸 U VO 〇 00 寸 〇〇 〇〇 〇〇 < r—H 〇 r—H m 煤炭種類-1 煤炭種類-2 (％ ϊ _) 寸撇 〇0 r- r—H 〇 〇 VO r—H 〇 〇 Oh 0.056 0.053 Μη 卜 〇 r- \ 1 i 〇 Mg〇 CNl f < 寸 1 < τ—H CaO 寸 m 〇 r—H Ό ON AhOs t—H 〇\ \ < CNl VO t—H Si〇2 a\ 00 寸 m 寸 CD Uh cn v〇 csi 〇 00 VO < PQ 瀠 m m m 遯 寸 ς 寸oIs/sCN6/ff}ii)_s?i細盔 g/rslIe 1223006 通氣、通液性，並降低爐下半部的壓力損失，同時熔鐵s i 濃度將降低’而執行滿意的低矽熔鐵之製造。而且亦可獲 得高爐操作的安定性。 4 ·其次’在將爐熱程度設定於通常水準，依塡入燒結礦 之s i 〇2含量更低的燒結礦，並降低高爐熔渣比，且將熔渣 的M g 0濃度提高至本發明範圔內的塡入原料配方條件進 行操作。結果’爐內通氣性保持於良好狀態，並確保高爐 操作的安定性，而且熔渣黏性將降低，循環區附近之高溫 反應區域中，Mg氣體分壓將上升，而可安定的製造低矽 熔鐵’上述M g氣體分壓上升的例子（參照實施例3、實施 例4)。此外，藉由提昇Si02含量較低燒結礦的高爐塡入 比率，便將提昇爐內還原性，而更加提昇生產性（參照實施 例 5 、 6) 〇 5 ·再者，在實施例7的高爐操作中，雖於實施例6的操 作條件內，將爐熱程度設定爲低於普通水準，但是藉由熔 渣流動性的改善效果作用，便可確保爐內通氣性並執行安 定操作，同時可製造Si濃度更低的熔鐵。 6 ·實施例8乃依幾乎如同實施例2的條件，但是微粉碳 吹送用噴槍3則採用偏心雙噴槍。（實施例1至7均使用單 噴槍）。結果將提昇微粉碳的燃燒性，並將高爐通氣性確保 於一定狀態，同時在實施例2中微粉碳200kg/t，但在實施 例8中則上升至2 1 6 k g /1，而且熔渣黏性、S i濃度均未上 升。 7 .實施例9乃依幾乎如同實施例6的條件，但是採用偏 24 312/發明說明書(補件)/92-04/92101454 1223006 心雙噴槍。此情況下，將微粉·碳設定爲2 00k g/t的結果， 將獲得熔渣比降低且Si濃度降低。 如上述，依照本發明的話，得知即便未特別降低爐熱程 度，且即便未將高爐熔渣比特別的降低，在1 50kg/t-熔鐵 以上的高PCR操作中，仍可在安定操作下製造低矽熔鐵。 此外，得知藉由將使用適度降低S i 02含量的燒結礦，並適 度的降低高爐熔渣比，或者適度降低爐熱程度等條件適度 的進行組合，便可在1 50kg/t-熔鐵以上的高PCR操作中， 在安定操作下製造S i濃度更低的熔鐵。 如上述，依照本發明的話，將不受原料供需步驟的限 制，在微粉碳爲150kg/t-熔鐵以上之高水準大量吹入高爐 操作中，將可安定的執行可抑制熔鐵之Si濃度的操作。此 情況下，並未必一定需要抑制爐熱程度的降低，且亦未必 一定需要嚴苛的限制高爐熔渣比上限。可提供此種朝高爐 吹入大量微粉碳的操作方法，並具工業上之有用效果。 【圖式簡單說明】 圖1(a)與（b)爲朝高爐吹送微粉碳之方法例的槪略縱切 剖圖。 圖2爲高爐熔渣之M gO含量與熔渣比之間的關係例圖。 圖3爲高爐熔渣之MgO含量與熔鐵Si含量之間的關係 例圖。 圖4爲高爐熔渣的MgO含量相對於該熔渣黏度計算値間 之關係例示圖。 圖5爲朝高爐吹送微粉碳之方法另一例的剖視圖。 25 312/發明說明書(補件)/92-04/92101454 圖6爲圖5之側視圖。 (元件符號說明） 1 高爐 2 吹管 3 微粉碳吹送用噴槍 4 風口 5 微粉碳 6 循環區 7 熱風 8 出鐵口 (〇) 吹管中心軸線 (1) 噴槍中心軸線 (L) 吹管軸線 1223006 312/發明說明書(補件)/92-04/921014540 (N 1223006 Example 9 CS1 1 § g CO inch r—Η υη i 1 1 1.27 1 〇〇 CS1 1 1504 I 0.19 inch · 1 < 〇0.028 destroy 〇 ◎ Example 8 ν〇1 03 r—H m c < \ oo 14 * 3 ″ A ι—Η m οο CS1 1 1505 I 0.23 1 inch · Γ On 〇0.025 壊 〇 ◎ Example 7 〇Csl 1 CN (N CO VO τ—Η ν〇r—Η r— < νο \ ο C0 1 1481 I 丨 〇 · 19 1 inch · ι .....! OO ci 0.031 壊 〇 ◎ Example 6 Different CN 1 〇t—H CO inch oo 1 15.0 1 r—Η ο 1 1503 I 1 0.26 1 VO τ—Η OO CD 1 0.031 1 Demolition ◎ Example 5 〇r—Η 1 〇〇m CO VO 1 1 < r Η 1 1 · 27 1 1 1501 1 1 0.27 1 inch · f 'i OO o 1 0.029 1 Example 〇 1 v〇oo i-4 mv〇oo τ-Η ν〇τ < ^ < C0 1 1497 1 1 0.27 1 v〇r-Η oo o 0.036 1 壊 〇 ◎ | Example 3 | sr—Η 1 ΙΟ oo CO CO vd 1 14.8 1 ▼ Η Γ Ο CSI 1508 1 0.22 1 inch · τ—Η oo o 1 0.023 1 Destruction 〇 Example 2 Ο Οί 1 v 〇r < j cn csi oo 1 14.3 1 I ία 1 οο οο CSI 1 1503 1 1 0.23 1 r—ί oo o 1 0.025 1 Destruction ◎ Example 1 Pan ti 1 CO V〇un 1 14.7 1 ι " 1 ν〇ΝΝ CN 1 1496 1 1 0.24 1 τ i oo CD 1 0.031 1 壊 〇〇 fine powder carbon blowing ratio (kg / t- Molten iron) Sinter-A Sinter-B Coke Mg0 (%) A12〇3 (%) CaO% / Si〇2% Slag ratio (kg / t-melted iron) Iron tapping temperature (° C) Melted iron Si Concentration (%) Overall blast furnace air permeability (-) Coke substitution rate 2) (%) Concentration of molten iron s (%) Slag duct overflows blast furnace operation stability Stability of slag viscosity Evaluation of raw material formula slag composition blast furnace operation Conditional blast furnace operation test (N inch SH0ICNJ6 / s-CNI6 / ff} ®) _g > Total helmet reduction / (ΝΙε 1223006 ττ (% ¥ «) O Csl m 00 1 < ν / Ί 〇〇r- v〇〇 OO inch ο 2 1.68 cn 00 ν · _Η E VO 00 mr—Η inch inch U VO 〇00 inch 〇〇〇〇〇〇〇 &r; H 〇r-H m coal type-1 coal type-2 (% ϊ _ ) Inch 〇0 r- r-H 〇〇VO r-H 〇〇Oh 0.056 0.053 Mn η 〇 〇r- \ 1 i 〇Mg〇CNl f < inch 1 < τ-H CaO inch m 〇r-H Ό ON AhOs t—H 〇 \ \ < CNl VO t—H Si〇2 a \ 00 inch m inch CD Uh cn v〇csi 〇00 VO < PQ 潆 mmm 遁 inch ς oIs / sCN6 / ff} ii) _s? I thin helmet g / rslIe 1223006 Ventilation and liquid permeability, and reduce pressure loss in the lower half of the furnace At the same time, the concentration of molten iron si will be reduced, and satisfactory low silicon molten iron manufacturing is performed. In addition, the stability of blast furnace operation can be obtained. 4 · Secondly, the furnace heat level is set at a normal level, the sinter ore with a lower si 〇2 content in the sinter ore is lowered, the slag ratio of the blast furnace is reduced, and the M g 0 concentration of the slag is increased to the present invention The operation of the raw material formula conditions within the range is carried out. As a result, the gas permeability in the furnace is maintained in a good state, and the stability of the blast furnace operation is ensured, and the viscosity of the slag will be reduced. In the high-temperature reaction zone near the circulation zone, the Mg gas partial pressure will rise, and low silicon can be manufactured stably. Examples of the above-mentioned increase in the partial pressure of the M g gas (see Examples 3 and 4). In addition, by increasing the blast furnace charge ratio of the sintered ore with a lower content of Si02, the reducibility in the furnace will be improved, and the productivity will be further improved (refer to Examples 5 and 6). 〇5. Furthermore, in the blast furnace of Example 7, During the operation, although the furnace heat level was set lower than the ordinary level in the operating conditions of Example 6, the effect of improving the slag fluidity can ensure the ventilation of the furnace and perform stable operations. Make molten iron with lower Si concentration. 6-Example 8 is almost the same as that of Example 2, except that the fine powder carbon blowing gun 3 uses an eccentric double gun. (Each of Examples 1 to 7 used a single spray gun). As a result, the flammability of the fine powder carbon will be improved, and the blast furnace air permeability will be ensured to a certain state. At the same time, the fine powder carbon was 200 kg / t in Example 2, but rose to 2 1 6 kg / 1 in Example 8, and the slag Neither viscosity nor Si concentration increased. 7. Example 9 is based on almost the same conditions as in Example 6, but with a partial 24 312 / Invention Specification (Supplement) / 92-04 / 92101454 1223006 heart dual spray gun. In this case, as a result of setting the fine powder and carbon to 200 k g / t, the slag ratio is reduced and the Si concentration is reduced. As described above, according to the present invention, it is learned that even if the degree of furnace heat is not particularly reduced, and even if the blast furnace slag ratio is not particularly reduced, stable operation can still be performed in a high PCR operation above 150 kg / t- molten iron. Manufacture of low silicon molten iron. In addition, it was learned that by using a combination of sinter ore with a moderate reduction in Si 02 content, a moderate reduction in the blast furnace slag ratio, or a moderate reduction in furnace heat, it was possible to achieve a melting weight of 150 kg / t-molten iron. In the above high PCR operation, a molten iron having a lower Si concentration was produced in a stable operation. As described above, according to the present invention, it will not be restricted by the supply and demand steps of the raw materials. When a large amount of fine powder carbon is 150kg / t- molten iron is blown into the blast furnace in a large amount, it can be stably performed to suppress the Si concentration of molten iron. Operation. In this case, it is not necessarily necessary to suppress the reduction in the degree of furnace heat, and it is not necessary to strictly limit the upper limit of the slag ratio of the blast furnace. Such a method for blowing a large amount of fine carbon into a blast furnace can be provided, and has industrially useful effects. [Brief description of the drawings] Figs. 1 (a) and (b) are schematic longitudinal sectional views of an example of a method for blowing fine powder carbon toward a blast furnace. FIG. 2 is a diagram showing an example of the relationship between the M gO content of the blast furnace slag and the slag ratio. Fig. 3 is a graph showing an example of the relationship between the MgO content of the blast furnace slag and the molten iron Si content. Fig. 4 is a graph showing an example of the relationship between the MgO content of the blast furnace slag and the calculated viscosity of the slag viscosity. Fig. 5 is a sectional view of another example of a method for blowing fine powder carbon toward a blast furnace. 25 312 / Invention Specification (Supplement) / 92-04 / 92101454 Figure 6 is a side view of Figure 5. (Description of component symbols) 1 Blast furnace 2 Blow tube 3 Spray gun for fine powder carbon blowing 4 Air outlet 5 Fine powder carbon 6 Circulation zone 7 Hot air 8 Iron outlet (〇) Blow tube center axis (1) Blow tube center axis (L) Blow tube axis 1223006 312 / Invention Instruction (Supplement) / 92-04 / 92101454