JP2018095935A - Preliminary treatment method for molten iron - Google Patents
Preliminary treatment method for molten iron Download PDFInfo
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- JP2018095935A JP2018095935A JP2016243106A JP2016243106A JP2018095935A JP 2018095935 A JP2018095935 A JP 2018095935A JP 2016243106 A JP2016243106 A JP 2016243106A JP 2016243106 A JP2016243106 A JP 2016243106A JP 2018095935 A JP2018095935 A JP 2018095935A
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- 238000000034 method Methods 0.000 title claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title abstract description 10
- 229910052742 iron Inorganic materials 0.000 title abstract description 5
- 239000002893 slag Substances 0.000 claims abstract description 54
- 230000001624 sedative effect Effects 0.000 claims description 47
- 239000000932 sedative agent Substances 0.000 claims description 43
- 229910052751 metal Inorganic materials 0.000 claims description 20
- 239000002184 metal Substances 0.000 claims description 20
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 229910001868 water Inorganic materials 0.000 claims description 7
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 6
- 238000002203 pretreatment Methods 0.000 claims description 4
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 3
- 238000003723 Smelting Methods 0.000 claims 1
- JYYOBHFYCIDXHH-UHFFFAOYSA-N carbonic acid;hydrate Chemical compound O.OC(O)=O JYYOBHFYCIDXHH-UHFFFAOYSA-N 0.000 claims 1
- 238000007664 blowing Methods 0.000 abstract description 7
- 238000005187 foaming Methods 0.000 abstract description 4
- 239000003139 biocide Substances 0.000 abstract 1
- 230000006866 deterioration Effects 0.000 abstract 1
- 206010039897 Sedation Diseases 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 230000036280 sedation Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 235000017550 sodium carbonate Nutrition 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- 235000012255 calcium oxide Nutrition 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229940125723 sedative agent Drugs 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- LQIAZOCLNBBZQK-UHFFFAOYSA-N 1-(1,2-Diphosphanylethyl)pyrrolidin-2-one Chemical compound PCC(P)N1CCCC1=O LQIAZOCLNBBZQK-UHFFFAOYSA-N 0.000 description 1
- 238000007088 Archimedes method Methods 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 230000001914 calming effect Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- MQRJBSHKWOFOGF-UHFFFAOYSA-L disodium;carbonate;hydrate Chemical compound O.[Na+].[Na+].[O-]C([O-])=O MQRJBSHKWOFOGF-UHFFFAOYSA-L 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Landscapes
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
Description
本発明は、スラグスロッピングを抑制する溶銑予備処理方法に関するものである。 The present invention relates to a hot metal pretreatment method for suppressing slag slopping.
従来から、溶銑脱りん工程では、精錬剤としてＣａＯおよび酸化鉄を含有する副原料を使用する。溶銑に添加した副原料は、溶銑と反応してスラグを生成する。また、脱りん反応と並行して、スラグ中の酸化鉄と溶銑中の炭素が反応してＣＯガスが発生し、フォーミングといわれるスラグの泡立ちが起こる。フォーミングは従来から知られており、特許文献１では、フォーミングに関する知見が開示されている。 Conventionally, in the hot metal dephosphorization process, auxiliary materials containing CaO and iron oxide are used as refining agents. The auxiliary material added to the hot metal reacts with the hot metal to produce slag. In parallel with the dephosphorization reaction, iron oxide in the slag reacts with carbon in the hot metal to generate CO gas, which causes foaming of slag called forming. Forming has been conventionally known, and Patent Document 1 discloses knowledge relating to forming.
ところで、フォーミングが著しくなると、反応容器からスラグが溢れる現象であるスロッピングが生じる。１４００℃以上と高温のスラグが大量に容器外に溢れることは、重機による清掃を要し、操業を阻害するなどの問題もあり、スロッピングの抑制が求められている。 By the way, when forming becomes remarkable, slapping which is a phenomenon in which slag overflows from the reaction vessel occurs. A large amount of hot slag as high as 1400 ° C. or more overflows outside the container, necessitating cleaning by heavy machinery and has problems such as hindering operation, and suppression of slopping is required.
本発明の課題は、スロッピングの発生による稼働率の低下を回避することである。 The subject of this invention is avoiding the fall of the operation rate by generation | occurrence | production of slopping.
上記課題を解決するためになされた本発明は次の手段を採用する。先ず、第一の手段は、溶銑予備処理の吹錬中であって、スラグフォーミング高さが転炉の炉底から炉口までの高さの８０％以上、１００％未満である間にスラグフォーミング鎮静剤を炉に投入することを特徴とする溶銑予備処理方法である。 The present invention made to solve the above problems employs the following means. First, the first means is during the blowing of the hot metal pretreatment, and the slag forming while the slag forming height is not less than 80% and less than 100% of the height from the bottom of the converter to the furnace port. It is a hot metal pretreatment method characterized by putting a sedative into a furnace.
第二の手段は、第一の手段において、スラグフォーミング鎮静剤の嵩密度は、２００ｋｇ／ｍ３以上４０００ｋｇ／ｍ３未満であるものとした溶銑予備処理方法である。 Second means, in the first means, the bulk density of the slag foaming sedatives are hot metal pretreatment process being in the range of less than 200 kg / m 3 or more 4000 kg / m 3.
第三の手段は、第一または第二の手段において、スラグフォーミング鎮静剤として水、炭酸カルシウム、炭酸ナトリウムのうち１種以上を含むものとした溶銑予備処理方法である。 The third means is a hot metal pretreatment method in the first or second means, which includes at least one of water, calcium carbonate, and sodium carbonate as a slag forming sedative.
本発明では、スロッピングの発生による稼働率の低下を回避することができる。また、スロッピング鎮静剤の使用量削減によるコスト削減を行うこともできる。 In the present invention, it is possible to avoid a reduction in operating rate due to the occurrence of slopping. In addition, cost reduction can be achieved by reducing the amount of slopping sedative used.
以下では、発明の実施形態について説明するが、まず、溶銑予備処理吹錬中のスラグフォーミングの挙動について説明する。吹錬の初期は、鉄鉱石や焼結鉱、ダストなどの固体酸素源を投入することにより、溶銑に含有するＳｉが酸化され、粘度の高いスラグが生成する。吹錬の中期に溶銑[Ｓｉ]濃度が０．０１％を下回るまでＳｉの酸化が進行すると、次第に溶銑に含有する炭素の酸化速度が増大し、ＣＯガス発生量が増加する。発生したガスはスラグ中に気泡として蓄積され、見かけの体積を膨張させる。膨張したスラグの高さが溶銑予備処理反応容器の炉口を超えると、スロッピングと呼ばれるスラグ漏出が起こる。 Below, although embodiment of invention is described, first, the behavior of the slag forming during hot metal pretreatment blowing is demonstrated. In the initial stage of blowing, by introducing a solid oxygen source such as iron ore, sintered ore, and dust, Si contained in the hot metal is oxidized, and slag having high viscosity is generated. As the oxidation of Si progresses until the hot metal [Si] concentration falls below 0.01% in the middle stage of blowing, the oxidation rate of carbon contained in the hot metal gradually increases and the amount of CO gas generation increases. The generated gas accumulates as bubbles in the slag and expands the apparent volume. When the height of the expanded slag exceeds the furnace opening of the hot metal pretreatment reaction vessel, slag leakage called slopping occurs.
フォーミングを鎮静させるために、ソーダ灰ブリケットなどの鎮静剤が使用されるが、本発明者らが鋭意検討することにより、鎮静剤を投入するタイミングによりフォーミングの鎮静やスロッピングの抑制の効果に優劣があることが判明した。スラグフォーミングおよび鎮静のメカニズムを詳細に検討したところ、鎮静効果の発現は鎮静剤からのガス発生により、スラグ中の気泡が凝集合体してガスが抜けること（破泡）によると推定された。従って、鎮静効果を十分に発揮するためには、鎮静剤を投入する時点で、ある程度のフォーミングが起こり、気泡がスラグに蓄積されていることが必要であるとの考えに至った。 Sedatives such as soda ash briquettes are used to soothe the forming, but the inventors have intensively studied and are superior or inferior to the effect of suppressing the forming and sloping at the timing when the sedative is added. Turned out to be. When the mechanism of slag forming and sedation was examined in detail, it was estimated that the sedation effect was manifested by the gas generation from the sedative and the bubbles in the slag being aggregated and coalesced (gas breakage). Therefore, in order to fully exert the sedative effect, it was thought that a certain amount of foaming occurred at the time when the sedative was added, and it was necessary that bubbles were accumulated in the slag.
本発明者は試験転炉、および実機転炉のオフライン実験による研究調査をおこなった。この研究調査から、図１に示すような結果が得られた。図１では横軸に気泡体積分率（％）を表し、縦軸にスラグ鎮静速度（高さ％／秒）を表している。なお、鎮静速度とは、フォーミングしていないスラグの高さから炉口までの距離を１００％とし、１秒あたりのスラグ高さ低減速度を百分率で表したものである。 The present inventor conducted a research investigation by an off-line experiment of a test converter and an actual converter. From this research study, the results shown in FIG. 1 were obtained. In FIG. 1, the horizontal axis represents the bubble volume fraction (%), and the vertical axis represents the slag sedation speed (height% / second). The sedation speed is the percentage of the slag height reduction rate per second with the distance from the unformed slag height to the furnace port as 100%.
実機操業においては一般的に、転炉の炉口から少量のスラグが溢れ始めてから、大量のスラグが溢れて炉下に落下しはじめるまで３０秒程度の時間がかかる。鎮静速度が０．３％毎秒以上であれば、この３０秒間でスラグフォーミング高さを１０％程度以上低下させることができるため、スロッピングの発生を抑えることができる。図１に示された結果から理解されるように、本発明者は、鎮静剤投入時のスラグ中気泡体積分率が６３％以上である場合に、鎮静速度が０．３％毎秒以上となることを見出した。つまりは、鎮静剤投入時のスラグ中気泡体積分率が６３％以上である場合に、スロッピングの発生を抑えることができることを見出した。 In actual operation, it generally takes about 30 seconds until a small amount of slag starts to overflow from the furnace port of the converter and starts to fall under the furnace. If the sedation speed is 0.3% or more per second, the slug forming height can be reduced by about 10% or more in this 30 seconds, so that the occurrence of slopping can be suppressed. As can be understood from the results shown in FIG. 1, the present inventor found that the sedation rate was 0.3% or more per second when the volume fraction of bubbles in the slag when the sedative was added was 63% or more. I found out. That is, it has been found that when the volume fraction of bubbles in the slag when the sedative is added is 63% or more, the occurrence of slopping can be suppressed.
ところで、気泡体積分率は、オフライン実験では取得可能であるが、オンラインで得ることが困難な数値である。このため、気泡体積分率の測定値を直接的な指標として操炉を行うことは困難である。そこで、前述の試験転炉、および実機転炉のオフライン実験において気泡体積分率とスラグ高さの関係を調べることにより、図２のごとくの結果を得た。図２では横軸にスラグ高さ（％）を表し、縦軸に気泡体積分率（％）を表している。この結果、気泡体積分率６３％に相当するスラグ高さは８０％であり、この高さ以上で鎮静剤を投入することにより、実用上有効な鎮静速度を達成できることが明らかになった。 By the way, the bubble volume fraction can be obtained in an offline experiment, but is a numerical value that is difficult to obtain online. For this reason, it is difficult to operate the furnace using the measured value of the bubble volume fraction as a direct index. Therefore, the results shown in FIG. 2 were obtained by examining the relationship between the bubble volume fraction and the slag height in the test converter and the off-line experiment of the actual converter. In FIG. 2, the horizontal axis represents slag height (%), and the vertical axis represents bubble volume fraction (%). As a result, the slag height corresponding to a bubble volume fraction of 63% was 80%, and it became clear that a practically effective sedation rate could be achieved by introducing a sedative above this height.
一方、鎮静剤を投入する時点でスラグフォーミング高さが高すぎると、鎮静剤がスラグ上面に乗った状態で反応容器外に排出されてしまうため、スロッピングの発生を抑えるという効果が発揮されない。このような事態は、スラグ高さが炉口の１００％までフォーミングしている状態で発生する。このような事態の発生を回避することも併せて考えたことから、スラグフォーミング高さが反応容器の炉底から炉口までの高さの８０％以上、１００％未満であるときに鎮静剤を投入することが、スロッピング防止のためには有効であることを見出した。なお、スラグフォーミング高さの測定は、どのような手段を採用しても良く、目視においておこなうことも、マイクロ波等を利用した各種計測機器を用いることも可能である。 On the other hand, if the slag forming height is too high at the time when the sedative is added, the sedative is discharged outside the reaction container in a state of riding on the upper surface of the slag, so that the effect of suppressing the occurrence of slopping is not exhibited. Such a situation occurs when the slag height is forming to 100% of the furnace opening. In consideration of avoiding such a situation, a sedative was added when the slag forming height was 80% or more and less than 100% of the height from the bottom of the reactor to the furnace port. It has been found that the introduction is effective for preventing slipping. The slag forming height can be measured by any means, and can be visually observed or various measuring devices using microwaves or the like can be used.
次に、鎮静剤の嵩密度について説明する。図３では、鎮静剤の嵩密度と鎮静剤の沈降深さについてのデータを示している。図３では横軸に鎮静剤密度（ｋｇ／ｍ３）を表し、縦軸は３０秒後の沈降深さ（ｍ）を表している。尚、鎮静剤の嵩密度は、表面を樹脂フィルムなどで覆った後、密度既知の液体（水など）に浸漬させたときの浮力から体積を求め（アルキメデス法）、空気中で測定した重量を用いて算出することができる。 Next, the bulk density of the sedative will be described. FIG. 3 shows data on the bulk density of the sedative and the settling depth of the sedative. In FIG. 3, the horizontal axis represents the sedative density (kg / m 3 ), and the vertical axis represents the settling depth (m) after 30 seconds. The bulk density of the sedative is obtained from the buoyancy when the surface is covered with a resin film or the like and then immersed in a liquid of known density (such as water) (Archimedes method). Can be used to calculate.
スロッピングが発生する限界である、炉口までフォーミングしたスラグの嵩密度、すなわちフォーミングスラグの最小嵩密度は約２００ｋｇ／ｍ３であるが、鎮静剤の嵩密度が２００ｋｇ／ｍ３未満であると、投入した鎮静剤の浮力が重力に勝るため、フォーミングスラグの表面に鎮静剤が乗った状態になる。したがって、図３に示すように、鎮静剤がフォーミングスラグの内部に侵入しない。この場合、鎮静剤の密度が２００ｋｇ／ｍ３以上の場合に比べて、鎮静剤のガス発生によるフォーミングの破泡効果が小さい。 The bulk density of the slag formed to the furnace opening, which is the limit at which slopping occurs, that is, the minimum bulk density of the forming slag is about 200 kg / m 3 , but the bulk density of the sedative is less than 200 kg / m 3 Since the buoyancy of the sedative that has been added is superior to gravity, the sedative is on the surface of the forming slag. Therefore, as shown in FIG. 3, the sedative does not enter the forming slag. In this case, compared with the case where the density of the sedative is 200 kg / m 3 or more, the foam breaking effect of forming due to gas generation of the sedative is small.
鎮静剤の嵩密度が４０００ｋｇ／ｍ３以上では、鎮静剤のフォーミングスラグ中の沈降速度が著しく速く、３０秒間で炉口までフォーミングしたスラグ高さである５ｍ以上沈降してしまう。この場合、スラグと接触する時間が短いため、鎮静効果が少ない。更に溶銑とスラグの界面に到達した鎮静剤は、ガス発生によってフォーミングを却って助長する現象を起こすために、好ましくない。このため、鎮静剤の嵩密度上限を４０００ｋｇ／ｍ３未満とするのが好ましい。つまり、投入する鎮静剤の嵩密度は、２００ｋｇ／ｍ３以上４０００ｋｇ／ｍ３未満が好適である。 When the bulk density of the sedative is 4000 kg / m 3 or more, the settling speed of the sedative in the forming slag is remarkably high, and the slag is formed at the height of 5 m or more which has been formed to the furnace opening in 30 seconds. In this case, since the time which contacts with slag is short, there are few sedative effects. Furthermore, a sedative that reaches the interface between the hot metal and the slag is not preferable because it causes a phenomenon in which the formation is promoted by gas generation. For this reason, it is preferable that the upper limit of the bulk density of the sedative is less than 4000 kg / m 3 . That is, the bulk density of the sedative to be added is preferably 200 kg / m 3 or more and less than 4000 kg / m 3 .
フォーミングを鎮静する鎮静剤としては、ガス発生物質として、水、炭酸カルシウム、炭酸ナトリウムのうち１種以上を用いることが望ましい。これらはいずれも工業的に安価かつ大量に入手可能な物質であるため、大きくコストを増大させずに効果を得ることが可能である。また、やや高価ではあるが、水酸化カルシウムなどの水酸化物を鎮静剤として用いることも可能である。水酸化物は、ガス状の水の発生源となり、鎮静剤の効果を発現する。同様に水和物であれば、ガス状の水の発生源となり、鎮静剤の効果を発現する。したがって、炭酸ナトリウム水和物であるソーダ灰は、二酸化炭素及びガス状の水の双方を発生させることができ、鎮静剤に好適である。 As a sedative for calming forming, it is desirable to use one or more of water, calcium carbonate, and sodium carbonate as gas generating substances. Since these are substances that are industrially inexpensive and available in large quantities, it is possible to obtain an effect without greatly increasing the cost. Moreover, although somewhat expensive, hydroxides such as calcium hydroxide can be used as a sedative. A hydroxide becomes a generation source of gaseous water and expresses the effect of a sedative. Similarly, if it is a hydrate, it becomes a generation source of gaseous water and exhibits the effect of a sedative. Therefore, soda ash which is sodium carbonate hydrate can generate both carbon dioxide and gaseous water, and is suitable as a sedative.
次に実機での操業試験結果を表１に示す。炉底から炉口までの高さ５．２ｍの転炉を用い、２７０ｔの溶銑を装入し、上方から挿入したランスで酸素を吹きつけ、副原料として鉄鉱石、ダスト、生石灰を投入して脱りん吹錬を行った。このときの炉口からのスラグ逸出量を、重機で回収した後に秤量した。炉口からスラグ逸出量が８００ｋｇを超えないことを合格判断基準とした。比較例１では、鎮静剤を用いずに操業を行い、吹錬中期で激しいスロッピングが発生した。比較例２では、石灰石を鎮静剤として投入したが、タイミングが早かったため、十分な鎮静効果が得られず、吹錬末期にスロッピングが発生した。比較例３では、炉口からスラグ高さが炉口までの高さの１００％、すなわち炉口からスラグが溢れ始めてから鎮静剤としてソーダ灰を投入したが、鎮静剤がスラグに乗って炉外に流出してしまい、鎮静効果が発揮できなかった。これに対し、実施例１〜６では、いずれも高い鎮静効果を発揮し、炉外に逸出したスラグ量は皆無か、または８００ｋｇ未満で操業を阻害する量ではなかった。 Next, Table 1 shows the results of operation tests on actual machines. Using a converter with a height of 5.2m from the bottom of the furnace to the furnace mouth, 270t hot metal was charged, oxygen was blown with a lance inserted from above, and iron ore, dust and quicklime were added as auxiliary materials. Dephosphorization was performed. The amount of slag escape from the furnace port at this time was weighed after being collected by a heavy machine. The acceptance criterion was that the amount of slag escape from the furnace port did not exceed 800 kg. In Comparative Example 1, the operation was performed without using a sedative, and severe slopping occurred in the middle of blowing. In Comparative Example 2, limestone was added as a sedative, but because the timing was early, a sufficient sedative effect could not be obtained and slapping occurred at the end of blowing. In Comparative Example 3, the slag height from the furnace port to 100% of the height from the furnace port, that is, soda ash was introduced as a sedative after the slag started to overflow from the furnace port, The sedative effect could not be demonstrated. On the other hand, in Examples 1-6, all showed the high sedative effect and the amount of slag which escaped out of the furnace was none, or it was not the quantity which inhibits operation at less than 800 kg.
実験結果からも理解されるように、本発明の条件では、スロッピング鎮静効果を十分に発揮でき、スロッピング発生比率を従来より低減できると考えられる。その結果、稼働率の低下を回避することができる。また、炉外に逸出するスラグには粒鉄が含まれているため、この量を削減することで歩留まりを向上させ、コスト削減を図ることができる。 As understood from the experimental results, the conditions of the present invention are considered to be able to sufficiently exhibit the slapping sedative effect and to reduce the ratio of occurrence of slopping as compared with the conventional case. As a result, a reduction in operating rate can be avoided. In addition, since slag that escapes from the furnace contains granular iron, reducing this amount can improve yield and reduce costs.
本発明は、以上の実施形態には限定されることは無く、本発明の趣旨を逸脱しない範囲で適応可能なことは勿論のことである。 The present invention is not limited to the above embodiment, and it is needless to say that the present invention can be applied without departing from the spirit of the present invention.
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