WO2021014918A1 - 溶鉄の脱りん方法 - Google Patents
溶鉄の脱りん方法 Download PDFInfo
- Publication number
- WO2021014918A1 WO2021014918A1 PCT/JP2020/025979 JP2020025979W WO2021014918A1 WO 2021014918 A1 WO2021014918 A1 WO 2021014918A1 JP 2020025979 W JP2020025979 W JP 2020025979W WO 2021014918 A1 WO2021014918 A1 WO 2021014918A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- slag
- molten iron
- blowing
- blown
- oxygen
- Prior art date
Links
Images
Classifications
-
- 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
- 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
-
- 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
- C21C5/42—Constructional features of converters
- C21C5/46—Details or accessories
Definitions
- the present invention relates to a method for dephosphorizing molten iron by blowing an oxygen-containing gas from a top-blown lance using a top-bottom blown converter in which molten iron and slag are charged.
- dephosphorization and refining of hot metal in a converter can be mentioned. It is known that the dephosphorization reaction proceeds by the reaction formula (1) at the slag-metal interface shown below. 2 [P] +2 (FeO) +3 (CaO ⁇ FeO) (l) ⁇ (3CaO ⁇ P 2 O 5 ) (s) +5 [Fe] ⁇ (1)
- [M] represents the element M in the hot metal
- (S) represents the chemical substance S in the slag.
- the dephosphorization reaction is an oxidation reaction, and the presence of iron oxide (FeO) is indispensable.
- the dephosphorization reaction is rate-determining supply of oxygen or calcium ferrite at the initial stage when the P concentration in the molten iron is high.
- the rate-determining of the supply of P to the slag-metal interface is obtained, so that bottom blowing gas stirring is also used in order to reduce the reached P concentration after the treatment.
- Patent Document 2 which pays attention to the fact that the dust concentration is low when the top-blown oxygen is not in contact with the hot metal, while the dust concentration is extremely increased when the top-blown oxygen is in contact with the hot metal, the dust concentration meter installed in the exhaust gas duct is used.
- a method has been proposed in which the presence or absence of contact between the blown oxygen and the hot metal is determined, and the top blown oxygen flow rate and / or the top blown lance height is adjusted to ensure non-contact blowing.
- the oxygen diffused in the slag is absorbed by the suspended granular iron and may not reach the surface of the molten iron. is there. Further, as a result of oxygen being absorbed by the grain iron, the time required for the grain iron to settle in the slag is longer than the blowing time, so even if iron oxide (FeO) is formed, the contribution at the slag-metal interface is small. Therefore, the progress of the dephosphorization reaction may be significantly low.
- FeO iron oxide
- the conventional lance technique as used in Patent Document 2 uses a lance when the slag does not penetrate. No measures can be taken during the slag other than lowering the height.
- FeO iron oxide
- the area where the jet flow collides with the molten iron bath surface (fire point area) is large from the viewpoint of the reaction boundary area. Is effective. Reducing the lance height directly leads to a reduction in the fire point area, which is not desirable because it reduces the dephosphorization reaction efficiency.
- the present invention solves the above-mentioned problems and stably supplies iron oxide (FeO) that contributes to the dephosphorization reaction at the slag-metal interface in the dephosphorization smelting using the upper bottom blow converter, and is an operation inhibitory factor. It is an object of the present invention to propose a method for dephosphorizing molten iron that suppresses slagging.
- FeO iron oxide
- the method for dephosphorizing molten iron of the present invention that advantageously solves the above problems is, firstly, When using an upper-bottom blown converter in which molten iron and slag are charged, oxygen-containing gas is blown from the upper-blow lance to remove phosphorus.
- the oxygen-containing gas is supplied as the main gas from the inlets of one or more main holes for blowing, which are arranged through the outer shell of the top blowing lance.
- a method for dephosphorizing molten iron that supplies control gas from an opening arranged on the inner wall surface of the main hole for blowing toward the axis of the main hole for blowing via a control gas supply path.
- a slag upper surface position measuring step for continuously or intermittently measuring an arbitrary upper surface position of the slag on the molten iron after measuring the molten iron upper surface position in advance.
- a slag top surface deviation calculation step for calculating the slag thickness, which is the difference between the measured molten iron and slag top surface positions, It is characterized by having an injection condition adjusting step for adjusting the injection condition of the oxygen-containing gas to be injected from the top blowing lance to a suitable range by using the obtained slag thickness.
- the method for dephosphorizing molten iron of the present invention that advantageously solves the above problems is secondly:
- oxygen-containing gas is blown from the upper-blow lance to remove phosphorus.
- the oxygen-containing gas is supplied as the main gas from the inlets of one or more main holes for blowing, which are arranged through the outer shell of the top blowing lance.
- a method for dephosphorizing molten iron that supplies control gas from an opening arranged on the inner wall surface of the main hole for blowing toward the axis of the main hole for blowing via a control gas supply path.
- the method for removing phosphorus from molten iron according to the present invention is as follows. a. The oxygen-containing gas injected from the top-blown lance penetrates the slag on the molten iron and reaches the upper surface of the molten iron. b. The dent depth of the molten iron due to the oxygen-containing gas penetrating the slag is less than 10% of the slag thickness. c. The adjustment of the injection conditions of the top blow lance is the adjustment of the ratio of the control gas supply pressure and the main gas supply pressure. d. The adjustment of the injection conditions of the top blow lance is the adjustment of the ratio between the control gas flow rate and the main gas flow rate. Can be a more preferred solution.
- the conditions for injecting oxygen-containing gas from the upper blown slag are appropriately adjusted, and in particular, the upper blown oxygen jet comes into contact with the molten iron.
- FIG. 1 is a schematic view showing a vertical cross section of the tip of a top blown lance 1 for a converter suitable for use in the method for dephosphorizing molten iron according to an embodiment of the present invention.
- FIG. 1 shows the lower end of the top blowing lance 1.
- the top blowing lance 1 is provided with one or more blowing main holes 3 for injecting oxygen-containing gas in the air storage tank 34 toward the hot water surface in the reaction vessel, and the control gas is provided in the blowing main holes 3.
- a control gas supply path 4 having an opening 41 arranged on the inner wall surface of each of the main holes 3 for blowing is provided.
- the opening 41 is configured so that the control gas is ejected toward the axis of the main hole 3 for blowing.
- the top blown lance 1 has a cooling water circulation path 2.
- the main hole 3 for blowing is formed in a continuous shape by combining two truncated cones.
- An opening 41 is formed on the inner wall surface of the throttle portion 32 of the main hole 3 for blowing, which has the smallest cross-sectional area.
- the shape of the main hole 3 for blowing is a so-called Laval nozzle.
- the oxygen-containing gas supplied to the main hole 3 for blowing may be, for example, an oxygen gas, and the control gas may be the same gas as the oxygen-containing gas or an inert gas such as nitrogen gas.
- the control gas is made to collide with the mainstream from a different direction with respect to the traveling direction of the mainstream in the nozzle (main hole 3 for blowing) of the upper blowing lance as shown in FIG.
- the mainstream flow path is changed to control the flow velocity.
- the flow path through which the mainstream flows is the entire cross section of the nozzle, but when the control gas is introduced, the mainstream flows while avoiding the control gas flow, so that the cross-sectional area of the mainstream flow path is limited.
- a fluid element is a general term for elements that utilize the functions obtained by the interference effect between a jet and a side wall, the collision effect between a jet and a jet, the fluid phenomenon caused by a vortex, and the effect of fluctuations in the flow velocity of the jet itself. It is being studied in the field.
- a control fluid supply port is arranged in the direction perpendicular to the jet flow near the outlet of the jet flow path.
- the drawing portion 32 is provided in the main hole for blowing to form a Laval nozzle as shown in FIG. 1, it is preferable to arrange the opening 41 in the vicinity of the drawing portion 32. Further, when the main hole 3 for blowing is a cylindrical straight nozzle having a constant pipe diameter, the opening 41 has a pipe diameter of 0.5 to 2 from the outlet 31 of the main hole 3 for blowing. It is preferable to arrange it on the inner wall which is 5 times deeper.
- the shape of the opening 41 of the control gas supply path 4 used in the present invention is a circular round hole, an elliptical elliptical hole, or a polygonal polygon when the inner wall surface of the blowing main hole 3 is developed in a plane. Holes, all-around slits, partial slits and the like can be preferably used.
- the openings 41 of the control gas supply path 4 are preferably provided at substantially equal intervals in the circumferential direction or have a slit shape. Of the circumferential length of the inner wall surface of the main hole 3 for blowing, the total length occupied by the opening 41 of the control gas supply path 4 is preferably 25% or more.
- the above-mentioned "approximately equal intervals in the circumferential direction” means that the distance S at the center position in the circumferential direction between the adjacent openings 41 is the center position in the circumferential direction between all the adjacent openings 41. It means that the distance is within ⁇ 20% of the average value of S AVE .
- the total length occupied by the opening 41 is less than 25%, the effect of contracting the mainstream oxygen-containing gas is small, and the effect of increasing the flow velocity of the injected gas may not be sufficient.
- FIG. 2 is a cross-sectional view of a converter showing the concept of implementing the method for dephosphorizing molten iron according to the present invention using the top-blown lance 1.
- the molten iron 6 and the slag 7 are charged in the converter type container 5, and during the blowing, the oxygen-containing gas is blown from the top blowing lance 1 while blowing the stirring gas from the bottom blowing tuyere 11. Spray as jet 8.
- the top blowing lance 1 is provided with a control gas from an opening 41 in the blowing main hole 3 via a main gas pipe 9 for supplying the main gas to the blowing main hole 3 and a control gas supply path 4. It has a control gas pipe 10 for supplying the above.
- the slag 7 is forming.
- the forming height of the slag 7, that is, the thickness of the slag is determined, and the flow rate of the control gas or the flow rate of the control gas or the flow rate of the control gas without changing the distance from the upper surface of the molten iron of the top jet lance 1 to the tip of the lance (lance height).
- the supply pressure is controlled to set the injection flow velocity of the top-blown jet 8 in an appropriate range, and the top-blown jet 8 penetrates the slag layer and comes into contact with the molten iron to efficiently dephosphorize the molten iron.
- the measurement of the height H S0 of the slag 7 that forming can be used microwave level gauge.
- the height H M0 Molten 6 can be measured by sub-lance.
- the slag thickness D S a value obtained by subtracting the molten iron height H M0 from the height H S0 of the measured forming slag.
- an arbitrary upper surface position of the slag on the molten iron during blowing is continuously or intermittently measured by, for example, a microwave level meter (top surface position measurement step).
- a microwave level meter top surface position measurement step
- the position of the upper surface of the molten iron measured using the sublance probe and the surface shape having the depth of the dent on the upper surface of the slag due to the injection of oxygen-containing gas from the upper blown lance, which will be described later, are obtained by numerical calculation or experiment, and actually measured first.
- the difference from the average slag upper surface position using the slag upper surface position is calculated as the slag thickness (slag upper surface deviation calculation step).
- the injection conditions of the oxygen-containing gas can be adjusted to a suitable range. Adjust to obtain the ideal surface shape (injection condition adjustment step).
- L S in the blowing for example, be calculated by combining equations (3) to the equation (2) below.
- the surface dent is formed by pushing slag and molten iron separately by the top-blown jet 8. It is formed as a dent in the slag until the top-blown jet 8 penetrates the slag 7. On the other hand, after the top-blown jet 8 penetrates the slag 7, it is formed as a recess of molten iron.
- L S L h ⁇ exp (-0.78 h / L h ) ⁇ ⁇ ⁇ (2)
- L h 63 ⁇ ( ⁇ S / ⁇ M ) -1/3 ⁇ ( FO2 / n / dt ) 2/3 ...
- L S a recess depth by oxygen jet, the vertical distance to the bottom of the recessed surface from the slag top before starting refining (m)
- h Vertical distance (m) from the tip of the lance to the upper surface of the slag before the start of refining
- ⁇ S Bulk density of forming slag (for example, 200 kg / m 3 )
- ⁇ M Density of molten iron (hot metal) (for example, 6900 kg / m 3 )
- FO2 Total top-blown oxygen flow rate (sum of main gas flow rate and control gas flow rate) (Nm 3 / h)
- n Number of nozzle holes (-) of top blowing lance 1 dt : Nozzle throat of top blowing lance 1 (main hole drawing portion 32 for blowing)
- Equation (2) surface indentations at the depth L S is equal to or slag thickness D S above, the top-blown jet 8, the slug 7 penetrates, it can be determined that has reached the molten iron 6.
- the equation (2) in calculating the surface recess depth L S in blowing, firstly, to measure any of the upper surface position measurement point 12 of the slag at such a microwave level gauge. Then, the molten iron and the height H M0 measured before treatment, slag height H S0 measured during blowing, top blowing lance tip height H L, the amount of slag obtained from the mass balance, slag composition and temperature, and the above composition, the temperature, the operating conditions such as the bulk density of the slag to be inferred from the amount of slag, in addition to the calculation of the slag thickness D S, depth of the depression in the slag top with an oxygen-containing gas ejected from the top lance L calculating the S, calculated as a result, when the recess depth L S of the slag top is greater than 110% of the slag thickness D S is the top-blown oxygen-containing gas to be injected from the lance of the main gas and the control gas adjust the pressure ratio
- the molten iron upper surface position and the slag upper surface position are measured in advance by the above method or the like, and then the initial slag thickness is calculated (slag thickness calculation step).
- the change in surface height during smelting is measured using a microwave level meter, etc., and at the same time, it is calculated from the mass balance during slag, for example, the amount of flux for dephosphorization, which is an operating factor, and the exhaust gas analysis value.
- the amount of iron oxide generated is grasped, the apparent bulk specific gravity of the slag is calculated, and it is used as a backup when it is difficult to detect the slag level with a microwave level meter due to dust generation (slag thickness fluctuation calculation step).
- the vertical component V of the injection rate of the oxygen-containing gas injected from the top-blown lance at the nozzle tip is determined as in the first embodiment.
- the slag layer penetrated to reach a value above the molten iron and slag through the oxygen-containing recess depth L M of the molten iron by gas is adjusted so, not exceed 10% of the thickness of the slag (injection condition adjusting step).
- the oxygen-containing gas injected from the top-blown lance penetrates the slag on the molten iron and reaches the upper surface of the molten iron.
- the reason is that when the top-blown oxygen jet penetrates the slag and comes into contact with molten iron, iron oxide (FeO) is generated at the contact point of the jet, that is, at the slag-metal interface, and the reaction formula (1) is removed. The phosphorus reaction is promoted.
- the depth recessed surface by top-blown oxygen jet L S is preferably set to such an extent that just through the slag. It is preferred dent depth L M of the molten iron with oxygen-containing gas passing through the slag is less than 10% of the slag thickness.
- the nozzle shape factor dt can be controlled without changing h related to the lance height and the total oxygen flow rate FO2 .
- the top blowing lance 1 having the shape shown in FIG. 1 according to the embodiment of the present invention and blowing the control gas from the opening 41 provided in the throttle portion 32 of the main hole 3 for blowing, the above-mentioned
- the fluid element of the above is configured, and the shape of the throttle portion 32 of the apparent main hole 3 for blowing is dynamically changed.
- the ratio of the control gas supply pressure to the main gas supply pressure: P a / P m , or the ratio of the control gas flow rate to the main gas flow rate: Q a / Q m is operated to make an apparent circle of the nozzle throat. It is realized that the equivalent diameter dt can be changed. As a result, a h according to the lance height remains constant, without changing the total oxygen flow rate F O2, it is possible to control the surface recess depth L S. That is, by controlling the surface recessed depth L S without reducing the fire spot area is the oxygen jet 8 top-blown can realize that penetrates the slag 7.
- Example 1 As an example of the first embodiment in which the dephosphorization treatment is efficiently performed by the method for dephosphorizing molten iron of the present invention, an upper bottom blowing converter is used, and oxygen is blown onto the hot metal by using a top blowing lance to blow oxygen into the hot metal.
- An actual machine test of converter dephosphorization treatment to remove phosphorus was conducted. Hot metal volume 283.8 tons, scrap 36.2 tons, bottom blowing gas flow rate 2400Nm 3 / h, number of main blowing holes for top blowing lance 5 holes, outlet diameter 0.071m, throat diameter 0.071m, opening
- the shape was an all-around slit shape with an opening width of 5.4 mm, and the P concentration before treatment was 0.125 mass%.
- the height of the upper surface of the slag at a radius of 2/3 from the center was measured from the furnace mouth with a microwave level gauge. Blowing before the start of the molten iron height H M0 was determined in advance by the sub-lance. During the blowing, dephosphorizing flux was blown at 10 kg / t per hot metal. This corresponds to increasing the total amount of slag by 10%.
- the molten iron height H M0 measured before treatment was calculated from the slag height H S0, measured using a microwave level meter, an initial slag thickness D S was 3.40M. Based on the equation (2) and (3), the surface depression depth L S is such that the 3.45 m, was initiated adjusted to dephosphorization blowing lance height and the oxygen-flow amount.
- the ratio L S / D S ⁇ 100 101.5% and top blowing jet of the surface depression depth L S and slag thickness D S is in the condition in contact with molten iron.
- the height of the upper surface of the slag was continuously measured using a microwave level meter during dephosphorization, and the average for 10 seconds was used as a representative value of the height of the slag surface. During the blowing, the amount of slag increased and the height of the slag surface increased due to the blowing of the dephosphorizing flux.
- Example 2 As an example of the second embodiment in which the dephosphorization treatment is efficiently performed by the method for dephosphorizing molten iron of the present invention, an upper bottom blown converter is used, and oxygen is blown onto the hot metal by using a top blown lance to blow oxygen into the hot metal.
- An actual machine test of converter dephosphorization treatment to remove phosphorus was conducted. Hot metal volume 283.8 tons, scrap 36.2 tons, bottom blowing gas flow rate 2400Nm 3 / h, number of main holes for blowing of top blowing lance 5, outlet diameter 0.071m, throat diameter 0.071m, opening shape
- the opening width was 5.4 mm, the circumference was slit-shaped, and the P concentration before treatment was 0.120 to 0.125 mass%.
- Process No. which controls the top-blown oxygen jet to penetrate the slag In Nos. 1 to 5, processing Nos. 1 to 5 were controlled so that the top-blown oxygen jet did not penetrate the slag.
- the amount of dephosphorization ⁇ P is higher than that of 7 and 8, and it can be seen that it is important for the top-blown oxygen jet to penetrate the slag in promoting the dephosphorization reaction in the top-bottom blown converter.
- the depth L S recessed surface for slag thickness D S is comparable processing No. Comparing 1 and 6, processing No.
- the amount of dephosphorization ⁇ P is higher in 1. It supplies a control gas blowing for main bore, presumably due to the controlled surface indentations depth L S while maintaining the fire spot area without reducing the lance height.
- molten iron recess depth L M is less than 10% of the slag thickness D S No.
- processing No. 6 and dephosphorization amount becomes dominant when compared as a reference, it is whereas molten iron recess depth L M is more than 10 percent of the slag thickness at processing No. 2 and 5 are processing Nos. It is about the same as or inferior to 6. Therefore, it is shown that making the surface dent excessively deep may diminish the effect of promoting the dephosphorization reaction.
- Table 2 shows the results of the operation in which the flow rate ratio Q a / Q m of the control gas and the main gas supplied to the top blowing lance was changed using the same device as in the second embodiment.
- the opening width was 5.4 mm, the circumference was slit-shaped, and the P concentration before treatment was 0.120 to 0.125 mass%.
- processing No. 9-11 are all surface depressions depth L S calculated in Equation (2) is to be larger than the slag thickness D S that is calculated from the measured values, and blowing while adjusting the control gas flow.
- processing No. 12 reduces the supply amount of the control gas, a surface recess depth L S and blowing so as to be less slag thickness D S.
- Processing No. which controls the top-blown oxygen jet to penetrate the slag In Nos. 9 to 11, processing Nos. 9 to 11 were controlled so that the top-blown oxygen jet did not penetrate the slag.
- the amount of dephosphorization ⁇ P was higher than that of Example 2, and the tendency was the same as in Example 2.
- the present invention is not limited to the scope of the above embodiment, and can be appropriately modified within the scope of the technical idea of the present invention.
- the molten iron is not limited to hot metal, but can also be applied to alloy molten iron such as manganese molten iron and chromium molten iron.
Landscapes
- 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)
Abstract
Description
2[P]+2(FeO)+3(CaO・FeO)(l)
→ (3CaO・P2O5)(s)+5[Fe] ・・・(1)
ここで、[M]は溶銑中の元素Mを表し、(S)はスラグ中の化学物質Sを表す。
(1)式よりわかる通り、脱りん反応は酸化反応であり、酸化鉄(FeO)の存在が不可欠である。また生成したりん酸化物(P2O5)は不安定であるので、石灰(CaO)と反応させて3CaO・P2O5として、スラグ中に安定化させる必要がある。そのため、脱りん精錬には、石灰が同様に不可欠である。スラグ中のFeOは上吹きランスから噴出される酸素含有ガスが火点にて溶鉄に吸収され、鉄を酸化することで生成する。また、りん酸化物と反応する石灰は、投入された時点では融点が2500℃以上であり、炉内温度1300~1500℃に比べ圧倒的に高く反応効率が著しく低位である。しかしながら、酸化鉄と反応して低融点のカルシウムフェライト(CaO・FeO)を形成することで滓化し、脱りん反応に寄与することになる。上記のことから酸化鉄は、直接Pを酸化するだけでなく、石灰の滓化を通じて脱りん反応効率の向上にも寄与することがわかる。また、上記脱りん反応は、溶鉄中のP濃度が高い初期は、酸素あるいはカルシウムフェライトの供給律速である。一方、P濃度が低くなった末期は、スラグ-メタル界面へのPの供給律速となるため、処理後到達P濃度を低下させるために底吹きガス攪拌が併用される。
転炉脱りんにおいては、上記で説明したように底吹きガスによる溶鉄の撹拌を組み込んだ上底吹き転炉の適用が広くなされている。しかし、特許文献1や特許文献2に記載の吹錬方法には底吹き条件への言及がなく、上吹き転炉における吹錬のみへの適用を検討した技術である。したがって、そのまま上底吹き転炉へ適用した際には操業に支障が現れる。例えば上底吹き転炉のスラグ中には、底吹きガスに基づく粒鉄が含有されていることが広く知られている。この粒鉄が含有されているスラグに対し上吹き噴流を貫通させないよう吹錬した際、スラグ中に拡散する酸素は懸濁している粒鉄に吸収されるため溶鉄の湯面まで到達できないおそれがある。また、粒鉄に酸素が吸収された結果、スラグ中の粒鉄の沈降にかかる時間は吹錬時間に対し長いので、酸化鉄(FeO)を形成してもスラグ―メタル界面での寄与が小さくなり、脱りん反応の進行が著しく低位となるおそれがある。
溶鉄とスラグとが装入された上底吹き転炉を用い、上吹きランスから酸素含有ガスを吹き付けて脱りん処理するにあたり、
前記上吹きランスの外殻を貫通して配置された1個以上の吹錬用主孔の入口からメインガスとして前記酸素含有ガスを供給し、
前記吹錬用主孔の内壁面に配置された開口部から、制御用ガス供給路を介して、前記吹錬用主孔の軸心に向けて制御用ガスを供給する溶鉄の脱りん処理方法であって、
事前に溶鉄上面位置を測定したうえで、前記溶鉄上にあるスラグの任意の上面位置を連続的もしくは間欠的に測定するスラグ上面位置測定ステップと、
測定された溶鉄およびスラグの上面位置の差であるスラグ厚みを算出するスラグ上面偏差算出ステップと、
得られたスラグ厚みを用いて、前記上吹きランスから噴射する前記酸素含有ガスの噴射条件を好適な範囲に調整する噴射条件調整ステップと、を有することを特徴とする。
溶鉄とスラグとが装入された上底吹き転炉を用い、上吹きランスから酸素含有ガスを吹き付けて脱りん処理するにあたり、
前記上吹きランスの外殻を貫通して配置された1個以上の吹錬用主孔の入口からメインガスとして前記酸素含有ガスを供給し、
前記吹錬用主孔の内壁面に配置された開口部から、制御用ガス供給路を介して、前記吹錬用主孔の軸心に向けて制御用ガスを供給する溶鉄の脱りん処理方法であって、
事前に溶鉄上面位置およびスラグ上面位置を測定したうえで、スラグ厚みを算出する初期スラグ厚み算出ステップと、
スラグ上面位置を吹錬時に連続的に測定しスラグ厚みの変動を算出するスラグ厚み変動算出ステップと、
得られた初期スラグ厚みとスラグ厚みの変動とを用いて、前記上吹きランスから噴射する前記酸素含有ガスの噴射条件を好適な範囲に調整する噴射条件調整ステップと、を有することを特徴とする。
a.前記上吹きランスから噴射された前記酸素含有ガスが溶鉄上のスラグを貫通し、溶鉄上面に達していること、
b.前記スラグを貫通した前記酸素含有ガスによる前記溶鉄の凹み深さが前記スラグ厚みの10%未満であること、
c.前記上吹きランスの噴射条件の調整が制御用ガス供給圧力とメインガス供給圧力との比の調整であること、
d.前記上吹きランスの噴射条件の調整が制御用ガス流量とメインガス流量との比の調整であること、
がより好ましい解決手段になり得るものと考えられる。
図1は、本発明の一実施形態に係る溶鉄の脱りん方法に用いるのに好適な転炉用上吹きランス1の先端の縦断面を示す模式図である。なお、図1では、上吹きランス1の下端部を示している。上吹きランス1は、貯気槽34内の酸素含有ガスを反応容器内湯面に向かって噴射する吹錬用主孔3を1個以上備えており、吹錬用主孔3内に制御用ガスを噴出させるためにそれぞれの吹錬用主孔3の内壁面に配置された開口部41を有する制御用ガス供給路4を備えている。この制御用ガスは、吹錬用主孔3の軸心に向かって噴出させるように開口部41が構成されている。上吹きランス1は、冷却水循環路2を有している。図1の例では、吹錬用主孔3は、2個の円錐台を組み合わせたつづみ状に形成されている。最も断面積が小さくなる吹錬用主孔3の絞り部32の内壁面に、開口部41が構成されている。この吹錬用主孔3の形状は、いわゆるラバールノズルである。なお、吹錬用主孔3に供給する酸素含有ガスは、例えば酸素ガスを用い、制御用ガスは、酸素含有ガスと同一のガスでもよいし、窒素ガスのような不活性ガスでもよい。
LS=Lh・exp(-0.78h/Lh) ・・・(2)
Lh=63×(ρS/ρM)-1/3×(FO2/n/dt)2/3・・・ (3)
ここで、LS :酸素ジェットによる凹み深さであり、精錬開始前のスラグ上面から表面凹みの底までの垂直距離とする(m)、
h :ランス先端から精錬開始前のスラグ上面までの垂直距離(m)、
Lh:h=0のときの表面凹み深さ(m)、
ρS:フォーミングスラグの嵩密度(たとえば、200kg/m3)、
ρM:溶鉄(溶銑)の密度(たとえば、6900kg/m3)、
FO2:上吹き総酸素流量(メインガス流量と制御用ガス流量の和)(Nm3/h)、
n :上吹きランス1のノズル孔数(-)、
dt:上吹きランス1のノズルスロート(吹錬用主孔絞り部32)直径(m)
を表す。
Vdt=0.73(LS+h)LS 1/2 ・・・(4)
但し、V:ノズル先端での噴射速度の鉛直成分(m/s)
dt=dt0(-0.09(Pa/Pm)+1) ・・・(5)
但し、dt0:開口部位置の吹錬用主孔の直径(mm)、
Pa:制御ガス供給圧力(ゲージ圧)、
Pm:メインガス供給圧力(ゲージ圧)
を表す。
また、実際に圧力を制御する際の操作因子は流量である。数式(5)を流量に関して整理すると以下の数式(5’)となる。
dt=dt0(-0.09(Am0・Qa)/(AaQm)+1) ・・・(5’)
但し、Qa:制御ガス流量、
Qm:メインガス流量、
Am0:開口部位置の吹錬用主孔断面積(mm2)、
Aa:制御用ガス供給のための開口部断面積(mm2)
を表す。
上記数式(5)(5’)からわかるように圧力比での制御と流量比での制御は等価であり、本発明を実施する際は圧力比で制御してもよいし、流量比で制御してもよい。
本発明の溶鉄の脱りん方法により、効率的に脱りん処理を行う第1の実施形態の一例として上底吹き転炉を利用し、溶銑へ上吹きランスを利用して酸素を吹き付け溶銑中のりんを除去する転炉脱りん処理実機試験を行った。溶銑量283.8トン、スクラップ36.2トン、底吹きガス流量2400Nm3/h、上吹きランスの吹錬用主孔の数5孔、出口径0.071m、スロート径0.071m、開口部形状は開き幅5.4mmの全周スリット状、処理前P濃度は0.125mass%であった。炉口からマイクロ波レベル計により、中心から2/3半径位置のスラグ上面位置の高さを測定した。吹錬開始前の溶鉄高さHM0は、事前にサブランスにより測定した。吹錬中には、脱りんフラックスを溶銑当たり10kg/t吹き込んだ。これはスラグの総量を10%増加させることに相当する。
数式(2)および(3)を基に、表面くぼみ深さLSが3.45mになるように、ランス高さおよび送酸量を調整して脱りん吹錬を開始した。ここで、表面くぼみ深さLSとスラグ厚みDSとの比LS/DS×100=101.5%と上吹き噴流が溶鉄に接触している条件となっている。
脱りん吹錬中にマイクロ波レベル計を用い連続的にスラグ上面高さを測定し、10秒間の平均を、スラグ表面高さの代表値とした。吹錬中には脱りんフラックスの吹込みにより、スラグ量が増量し、スラグ表面高さが増加した。
本発明法として、吹錬の初期から終了までLS/DS×100=101.5%を維持するように制御用ガス比を調整して吹錬した場合には、初期溶鉄のP濃度[mass%]と吹錬終了後の溶鉄のP濃度[mass%]との差である脱りん量ΔPが0.115mass%であった。
一方、スラグ量の増量に伴って、上吹き噴流が溶鉄に到達しない条件で吹錬した場合には、同じ総送酸量であっても、脱りん量ΔPが0.068mass%に留まった。
本発明の溶鉄の脱りん方法により、効率的に脱りん処理を行う第2の実施形態の一例として上底吹き転炉を利用し、溶銑へ上吹きランスを利用して酸素を吹き付け溶銑中のりんを除去する転炉脱りん処理実機試験を行った。溶銑量283.8トン、スクラップ36.2トン、底吹きガス流量2400Nm3/h、上吹きランスの吹錬用主孔の数5、出口径0.071m、スロート径0.071m、開口部形状は開き幅5.4mmの全周スリット状、処理前P濃度0.120~0.125mass%であった。
実機脱りん炉において、制御用ガスの供給圧力とメインガス供給圧力との比を制御して、表面凹み深さLSを数式(2)で算出し、他方、操業条件、例えば初期スラグ量や脱燐フラックス吹き込み量、スラグ組成やスラグ温度から求まるスラグの嵩密度などから動的なスラグ高さDSを算出し、上吹き噴流のスラグ貫通有無を管理しながら操業を行った結果を表1に示す。表1に示す表面凹み深さLSおよびスラグ高さDSは、吹錬終了時の値を示す。
なお表1における脱りん量ΔP[mass%]は、実施例1と同じである。
また、スラグ厚みDSに対する表面凹み深さLSが同程度である処理No.1および6を比較すると、処理No.1の方が脱りん量ΔPが高位である。これは、吹錬用主孔内に制御ガスを供給し、ランス高さを減じることなく火点面積を保持したまま表面凹み深さLSを制御したことによるものと考えられる。さらに、スラグ厚みDSに対する表面凹み深さLSがスラグ厚みDSの10%より小さい条件、つまり、溶鉄凹み深さLMがスラグ厚みDSの10%未満であるNo.1、3および4では処理No.6を基準として比較した際の脱りん量が優位となっており、一方で溶鉄凹み深さLMがスラグ厚みの10%以上である処理No.2および5は処理No.6と同程度か、劣っている。したがって、表面凹みを過剰に深くすることは脱りん反応の促進効果を減殺してしまうおそれがあることを示している。
実施例2と同様の装置を用い、上吹きランスに供給する制御用ガスとメインガスの流量比Qa/Qmを変更して操業を行った結果を表2に示す。溶銑量283.8トン、スクラップ36.2トン、底吹きガス流量2400Nm3/h、上吹きランスの吹錬用主孔の数5、出口径0.071m、スロート径0.071m、開口部形状は開き幅5.4mmの全周スリット状、処理前P濃度 0.120~0.125mass%であった。実機脱りん炉において、制御用ガスの供給流量とメインガス供給流量との比を制御して、表面凹み深さLSを数式(2)および(5’)で算出し、他方、操業条件、例えば初期スラグ量や脱燐フラックス吹き込み量、スラグ組成やスラグ温度から求まるスラグの嵩密度などから動的なスラグ高さDSを算出し、上吹き噴流のスラグ貫通有無を管理しながら操業を行った結果を表2に示す。表2に示す表面凹み深さLSおよびスラグ高さDSは、吹錬終了時の値を示す。
2 冷却水循環路
3 吹錬用主孔
31 吹錬用主孔出口
32 吹錬用主孔絞り部
33 吹錬用主孔入口
34 貯気槽
4 制御用ガス供給路
41 開口部
5 転炉型容器
6 溶鉄
7 スラグ
8 上吹き噴流
9 メインガス配管
10 制御用ガス配管
11 底吹き羽口
12 スラグ上面位置測定点
Claims (6)
- 溶鉄とスラグとが装入された上底吹き転炉を用い、上吹きランスから酸素含有ガスを吹き付けて脱りん処理するにあたり、
前記上吹きランスの外殻を貫通して配置された1個以上の吹錬用主孔の入口からメインガスとして前記酸素含有ガスを供給し、
前記吹錬用主孔の内壁面に配置された開口部から、制御用ガス供給路を介して、前記吹錬用主孔の軸心に向けて制御用ガスを供給する溶鉄の脱りん処理方法であって、
事前に溶鉄上面位置を測定したうえで、前記溶鉄上にあるスラグの任意の上面位置を連続的もしくは間欠的に測定するスラグ上面位置測定ステップと、
測定された溶鉄およびスラグの上面位置の差であるスラグ厚みを算出するスラグ上面偏差算出ステップと、
得られたスラグ厚みを用いて、前記上吹きランスから噴射する前記酸素含有ガスの噴射条件を好適な範囲に調整する噴射条件調整ステップと、を有することを特徴とする溶鉄の脱りん方法。 - 溶鉄とスラグとが装入された上底吹き転炉を用い、上吹きランスから酸素含有ガスを吹き付けて脱りん処理するにあたり、
前記上吹きランスの外殻を貫通して配置された1個以上の吹錬用主孔の入口からメインガスとして前記酸素含有ガスを供給し、
前記吹錬用主孔の内壁面に配置された開口部から、制御用ガス供給路を介して、前記吹錬用主孔の軸心に向けて制御用ガスを供給する溶鉄の脱りん処理方法であって、
事前に溶鉄上面位置およびスラグ上面位置を測定したうえで、スラグ厚みを算出する初期スラグ厚み算出ステップと、
スラグ上面位置を吹錬時に連続的に測定しスラグ厚みの変動を算出するスラグ厚み変動算出ステップと、
得られた初期スラグ厚みとスラグ厚みの変動とを用いて、前記上吹きランスから噴射する前記酸素含有ガスの噴射条件を好適な範囲に調整する噴射条件調整ステップと、を有することを特徴とする溶鉄の脱りん方法。 - 前記上吹きランスから噴射された前記酸素含有ガスが溶鉄上のスラグを貫通し、溶鉄上面に達していることを特徴とする請求項1または2に記載の溶鉄の脱りん方法。
- 前記スラグを貫通した前記酸素含有ガスによる前記溶鉄の凹み深さが前記スラグの厚みの10%未満であることを特徴とする請求項3に記載の溶鉄の脱りん方法。
- 前記上吹きランスの噴射条件の調整が制御用ガス供給圧力とメインガス供給圧力との比の調整であることを特徴とする請求項1から4のいずれか1項に記載の溶鉄の脱りん方法。
- 前記上吹きランスの噴射条件の調整が制御用ガス流量とメインガス流量との比の調整であることを特徴とする請求項1から4のいずれか1項に記載の溶鉄の脱りん方法。
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2020554562A JP6813144B1 (ja) | 2019-07-22 | 2020-07-02 | 溶鉄の脱りん方法 |
US17/626,083 US20220259686A1 (en) | 2019-07-22 | 2020-07-02 | Molten iron dephosphorization method |
CN202080050175.7A CN114096685A (zh) | 2019-07-22 | 2020-07-02 | 铁水的脱磷方法 |
KR1020217040429A KR102559151B1 (ko) | 2019-07-22 | 2020-07-02 | 용철의 탈인 방법 |
BR112022000040-5A BR112022000040B1 (pt) | 2019-07-22 | 2020-07-02 | Método de desfosforização de ferro fundido |
EP20843908.3A EP4006176B1 (en) | 2019-07-22 | 2020-07-02 | Molten iron dephosphorization method |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2019134742 | 2019-07-22 | ||
JP2019-134742 | 2019-07-22 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2021014918A1 true WO2021014918A1 (ja) | 2021-01-28 |
Family
ID=74193205
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2020/025979 WO2021014918A1 (ja) | 2019-07-22 | 2020-07-02 | 溶鉄の脱りん方法 |
Country Status (2)
Country | Link |
---|---|
TW (1) | TWI737398B (ja) |
WO (1) | WO2021014918A1 (ja) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005139529A (ja) * | 2003-11-10 | 2005-06-02 | Nippon Steel Corp | 溶銑の脱燐精錬方法 |
JP2015101734A (ja) | 2013-11-21 | 2015-06-04 | 新日鐵住金株式会社 | 転炉吹錬用上吹きランス |
JP2017052976A (ja) * | 2015-09-07 | 2017-03-16 | Jfeスチール株式会社 | 溶銑の精錬方法 |
JP2017101294A (ja) * | 2015-12-02 | 2017-06-08 | 株式会社神戸製鋼所 | 溶銑の脱りん処理における固体酸素源の供給方法 |
WO2019123873A1 (ja) * | 2017-12-22 | 2019-06-27 | Jfeスチール株式会社 | 溶鉄の送酸精錬方法及び上吹きランス |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2018135351A1 (ja) * | 2017-01-18 | 2018-07-26 | Jfeスチール株式会社 | 溶銑の脱燐方法 |
-
2020
- 2020-07-02 WO PCT/JP2020/025979 patent/WO2021014918A1/ja unknown
- 2020-07-10 TW TW109123335A patent/TWI737398B/zh active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005139529A (ja) * | 2003-11-10 | 2005-06-02 | Nippon Steel Corp | 溶銑の脱燐精錬方法 |
JP2015101734A (ja) | 2013-11-21 | 2015-06-04 | 新日鐵住金株式会社 | 転炉吹錬用上吹きランス |
JP2017052976A (ja) * | 2015-09-07 | 2017-03-16 | Jfeスチール株式会社 | 溶銑の精錬方法 |
JP2017101294A (ja) * | 2015-12-02 | 2017-06-08 | 株式会社神戸製鋼所 | 溶銑の脱りん処理における固体酸素源の供給方法 |
WO2019123873A1 (ja) * | 2017-12-22 | 2019-06-27 | Jfeスチール株式会社 | 溶鉄の送酸精錬方法及び上吹きランス |
Also Published As
Publication number | Publication date |
---|---|
TWI737398B (zh) | 2021-08-21 |
TW202104600A (zh) | 2021-02-01 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6660044B2 (ja) | 溶鉄の送酸精錬方法及び上吹きランス | |
JP6813144B1 (ja) | 溶鉄の脱りん方法 | |
WO2021014918A1 (ja) | 溶鉄の脱りん方法 | |
JP2007239082A (ja) | 溶融金属の酸化精錬方法及び精錬用上吹きランス | |
JP6141445B2 (ja) | ランスおよびこれを用いた操業方法 | |
JP2000309816A (ja) | 含Cr溶鋼の脱炭精錬方法 | |
RU2773179C1 (ru) | Способ дефосфорации расплавленного чугуна | |
JP5915568B2 (ja) | 転炉型精錬炉における溶銑の精錬方法 | |
JP4686880B2 (ja) | 溶銑の脱燐方法 | |
JP7380444B2 (ja) | 転炉脱りん処理用上吹きランスおよび転炉吹錬方法 | |
JP4419594B2 (ja) | 溶銑の精錬方法 | |
JP6939828B2 (ja) | 溶鉄の送酸精錬方法 | |
JP2808197B2 (ja) | 大径浸漬管による溶鋼の真空精錬法 | |
JP4025713B2 (ja) | 溶銑の脱燐精錬方法 | |
JP5332487B2 (ja) | 溶銑の脱珪処理方法 | |
BR112022000040B1 (pt) | Método de desfosforização de ferro fundido | |
JP6760237B2 (ja) | 溶銑の脱珪処理方法 | |
JPH1143714A (ja) | 精錬用ランス | |
JP2004115910A (ja) | 溶銑の精錬方法 | |
JP2003138312A (ja) | 溶融金属精錬方法及び溶融金属精錬用上吹きランス | |
JP2019173050A (ja) | 溶銑の脱珪処理方法 | |
JP5223228B2 (ja) | 溶銑の脱珪処理方法 | |
JP2008255421A (ja) | 溶鋼の加熱方法 | |
JPH0361315A (ja) | 極低炭素鋼の溶製方法 | |
JPH0361318A (ja) | 極低炭素鋼の溶製方法 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
ENP | Entry into the national phase |
Ref document number: 2020554562 Country of ref document: JP Kind code of ref document: A |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 20843908 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 20217040429 Country of ref document: KR Kind code of ref document: A |
|
REG | Reference to national code |
Ref country code: BR Ref legal event code: B01A Ref document number: 112022000040 Country of ref document: BR |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 112022000040 Country of ref document: BR Kind code of ref document: A2 Effective date: 20220103 |
|
ENP | Entry into the national phase |
Ref document number: 2020843908 Country of ref document: EP Effective date: 20220222 |