WO2015011910A1 - Method for removing phosphorus from hot metal - Google Patents
Method for removing phosphorus from hot metal Download PDFInfo
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- WO2015011910A1 WO2015011910A1 PCT/JP2014/003828 JP2014003828W WO2015011910A1 WO 2015011910 A1 WO2015011910 A1 WO 2015011910A1 JP 2014003828 W JP2014003828 W JP 2014003828W WO 2015011910 A1 WO2015011910 A1 WO 2015011910A1
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- cao
- amount
- dephosphorization
- hot metal
- oxygen
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/35—Blowing from above and through the bath
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—Agents used for dephosphorising or desulfurising
Definitions
- oxygen gas is blown from the top blowing lance to the hot metal in the converter-type refining furnace, and the dephosphorization medium solvent mainly composed of CaO is applied to the collision surface of the oxygen gas with the hot metal bath surface.
- the present invention relates to a hot metal dephosphorization method performed by spraying through a blowing lance.
- This hot metal dephosphorization treatment is performed by adding a dephosphorization medium solvent mainly composed of CaO such as quicklime and adding an oxygen source such as oxygen gas or iron oxide as a dephosphorization agent.
- Source oxidizes phosphorus in the hot metal, and the resulting phosphor oxide (P 2 O 5 ) is converted into 3CaO ⁇ P 2 O 5 (“Ca 3 (PO 4 )
- the dephosphorization medium solvent to be used must contain CaO.
- the ratio of the oxygen source supply rate and the CaO supply rate is specified to increase the dephosphorization efficiency, or the FeO concentration of the slag to be generated is specified to increase the dephosphorization efficiency.
- Patent Document 1 when an oxygen source is added to hot metal in hot metal dephosphorization, the addition rate of the oxygen source is X (kg / min), and the addition rate of the dephosphorization medium solvent in terms of CaO is Y. (Kg / min), the dephosphorization medium solvent as the CaO source is added to the hot metal under the condition of satisfying “0.50 ⁇ X / Y ⁇ 2.0” with respect to the addition rate X of the oxygen source.
- a method for hot metal treatment has been proposed. In this method, FeO is generated by an oxygen source to be supplied, and the concentration of FeO in the slag is increased to improve the dephosphorization efficiency.
- Patent Document 2 when a hot metal is dephosphorized using a dephosphorization medium solvent that does not substantially contain fluorine using a converter type furnace,
- the slag basicity ((mass% CaO) / (mass% SiO 2 )) defined by the mass concentration ratio of CaO and SiO 2 is 2.5 or more and 3.5 or less
- the hot metal temperature after the dephosphorization treatment is By depressurizing from 1320 ° C to 1380 ° C and maintaining the bottom blowing gas flow rate at 0.18 Nm 3 / min or less per ton of hot metal from before 60% of the total blowing time has elapsed until the end of blowing.
- T. in slag after treatment A method of dephosphorizing with an Fe concentration of 5% by mass or more has been proposed.
- Patent Document 3 discloses a method for producing low-phosphorus hot metal in which a refining agent as gaseous oxygen and a CaO source is sprayed through an upper blowing lance, and the amount of slag after treatment is 30 kg / molten-ton or less. .
- Patent Document 4 when a furnace of a converter type is used and a CaO 2 containing material is not used and a CaO containing powder is blown up together with an oxygen containing gas from a lance, the hot metal is dephosphorized.
- hot metal having a silicon content [Si] (mass%) of 0.30 or more before treatment, the top blowing rate (kg / min) of pure CaO in the CaO-containing powder and the mass flow rate of oxygen gas (kg) / Min)
- a hot metal dephosphorization method in which the value of the ratio to 0.56 + 0.5 ⁇ [Si] to 0.56 + 1.5 ⁇ [Si] is proposed.
- Patent Document 1 since the range of the ratio (X / Y) of the oxygen source addition rate and the CaO equivalent addition rate of the dephosphorization medium solvent is wide, under conditions where the silicon content of the hot metal is high, In some cases, a high dephosphorization amount cannot be maintained. That is, it is not possible to stably carry out an efficient dephosphorization process without being affected by the silicon content of the hot metal. Therefore, for the purpose of promoting the dissolution of the cold iron source in the dephosphorization process, the technique of Patent Document 1 cannot be applied to an operation in which the content of silicon in the hot metal, which is a heat source, is increased. The present inventors have confirmed that Patent Document 1 is suitable when the silicon content of the hot metal is 0.10% by mass or less.
- Patent Document 2 only defines the basicity of slag after dephosphorization treatment. Although the basicity of slag is an important factor in dephosphorization treatment, the basicity of slag after dephosphorization treatment is disclosed in Patent Document 2. Even if it secures like this, the case where dephosphorization is insufficient occurs. That is, as in Patent Document 2, it is not possible to stably carry out efficient dephosphorization simply by defining the basicity of slag after dephosphorization.
- Patent Document 3 discloses a hot metal dephosphorization method in which a refining agent as a CaO source and gaseous oxygen are blown up, and the ratio between the supply rate of gaseous oxygen and the supply rate of pure CaO is within a specific range. Teaching that it is advantageous to phosphorus. However, this technique is based on the premise that the silicon content of hot metal before processing is as low as 0.15% by mass or less, and the slag amount after processing is 30 kg / hot metal-ton or less. In the case of dephosphorizing hot metal that has not been sufficiently reduced in amount, the phosphorus removal efficiency may be low and the phosphorus content of the hot metal may not be sufficiently reduced.
- Patent Document 4 discloses that in a hot metal dephosphorization treatment method in which CaO-containing powder and gaseous oxygen are blown up, when the silicon content of the hot metal before the treatment is as high as 0.30% by mass or more, An operation guideline is given for the value of the ratio between the blowing rate (kg / min) and the mass flow rate (kg / min) of oxygen gas.
- the higher the silicon content of the hot metal before the treatment the higher the appropriate range of the ratio of the top blowing rate of CaO pure and the oxygen gas mass flow rate to the higher value side, and the total amount of oxygen gas. Since the supply amount also increases, when the silicon content of the hot metal is large, the supply amount of the CaO-containing powder becomes excessive and the amount of slag increases, making it difficult to perform an efficient dephosphorization treatment.
- the present invention has been made in view of the above circumstances, and its object is to blow oxygen gas from the top blowing lance onto the hot metal in the converter-type refining furnace and to impinge the oxygen gas on the hot metal bath surface.
- the hot metal is dephosphorized by spraying a dephosphorization medium solvent mainly composed of CaO through the upper blowing lance
- the oxygen from the upper blowing lance depends on the amount of oxygen gas supplied from the upper blowing lance. It is an object to provide a hot metal dephosphorization method that enables a dephosphorization reaction to be performed efficiently by appropriately adjusting the supply amount of a dephosphorization medium solvent.
- the gist of the present invention for solving the above problems is as follows.
- Oxygen gas is blown from the top blowing lance to the hot metal in the converter-type refining furnace, and a dephosphorization medium solvent mainly composed of CaO is passed through the upper blowing lance to the collision surface of the oxygen gas with the hot metal.
- the dephosphorization treatment method the phosphorus in the hot metal is removed by oxidizing the phosphorus in the hot metal with the oxygen gas and taking the generated phosphor oxide into the hatched dephosphorization medium solvent.
- the oxygen gas excluding the portion used for the desiliconization reaction out of the oxygen gas supplied into the furnace is deoxygenated outside oxygen.
- the amount (kg / molten-ton) is defined, the amount of CaO (kg / molten-ton) in the dephosphorization medium solvent containing CaO as a main component added by spraying from the top blowing lance to the molten iron bath surface, The ratio [CaO amount / outside silicon removal amount] with the outside silicon removal amount To be less than .90, adjusting the addition amount of the medium solvent for dephosphorization is added blown from the top lance according to de ⁇ oxygen, dephosphorization method hot metal.
- the addition amount of the dephosphorization medium solvent containing CaO as a main component and added by spraying from the top blowing lance is adjusted so that the CaO outside desiliconization is in the range of 6-9 kg / molten-ton.
- the hot metal is dephosphorized with the ratio [CaO amount / oxygen concentration outside desiliconization] in the range of less than 0.80, the top blown so that the non-desiliconization CaO is 8 kg / molten iron-ton or more.
- Dephosphorization with CaO as main component, sprayed from lance Adjusting the addition amount of the solvent, dephosphorization method hot metal according to the above [1].
- the ratio of the amount of CaO and the amount of oxygen outside desiliconized in the dephosphorization medium solvent containing CaO as a main component added from the top blowing lance [CaO amount / the amount of oxygen outside desiliconized] Since the dephosphorization treatment is performed within a range in which the dephosphorization efficiency of CaO in the dephosphorization medium solvent containing as a main component is high, the added dephosphorization medium solvent containing CaO as the main component is generated. As a result, the phosphorous oxide (P 2 O 5 ) is efficiently absorbed, and as a result, it is possible to perform the dephosphorization treatment more efficiently than in the prior art.
- FIG. 1 is a schematic diagram showing an example of a converter-type refining furnace suitable for carrying out the present invention.
- FIG. 2 is a graph showing the relationship between the ratio [CaO amount / oxygen content outside desiliconization] and dephosphorization lime efficiency.
- FIG. 3 shows dephosphorization when the hot metal is dephosphorized with an oxygen content outside desiliconization of 11 to 13 Nm 3 / molten iron-ton and a ratio [CaO content / oxygen content outside desiliconization] of 0.80 or more and less than 0.90. It is a figure which shows the relationship between the silicon concentration in the hot metal before a process, and the phosphorus concentration in the hot metal after a dephosphorization process.
- FIG. 1 is a schematic diagram showing an example of a converter-type refining furnace suitable for carrying out the present invention.
- FIG. 2 is a graph showing the relationship between the ratio [CaO amount / oxygen content outside desiliconization] and dephosphorization lime efficiency.
- FIG. 4 is a diagram showing the results of investigating the relationship between non-silicaization CaO and the amount of dephosphorization when the ratio [CaO amount / oxygen concentration outside desiliconization] is less than 0.70.
- FIG. 5 is a diagram showing the results of investigating the relationship between the non-silicad CaO and the dephosphorization amount in the case where the ratio [CaO amount / oxygen concentration outside desiliconization] is 0.70 or more and less than 0.80.
- FIG. 6 is a diagram showing the results of investigating the relationship between the non-silicad CaO and the dephosphorization amount when the ratio [CaO amount / desiliconized oxygen amount] is 0.80 or more and less than 0.90.
- FIG. 7 is a diagram showing the results of investigating the relationship between the non-siliconized CaO and the dephosphorization amount when the ratio [CaO amount / oxygen-free silicon amount] is 0.90 or more and less than 1.00.
- FIG. 8 is a diagram showing the relationship between the carbon concentration in the hot metal after the dephosphorization treatment and the phosphorus concentration in the hot metal in the present invention example 1 and the conventional example 1 in comparison.
- FIG. 9 is a diagram showing the relationship between the silicon concentration in the hot metal before the dephosphorization treatment and the amount of CaO used in the dephosphorization treatment in comparison between the present invention example 2 and the conventional example 2.
- FIG. 10 is a diagram showing a relationship between the silicon concentration in the hot metal before the dephosphorization treatment and the dephosphorization amount of the hot metal in the dephosphorization treatment in comparison between Example 2 of the present invention and Conventional Example 2.
- the hot metal used in the dephosphorization process according to the present invention is a hot metal manufactured in a hot metal manufacturing facility such as a blast furnace, and the hot metal manufactured in the hot metal manufacturing facility is received in a hot metal transport container such as a hot metal ladle or a kneading car. Then, the received hot metal is transported to a converter-type smelting furnace facility for performing dephosphorization treatment.
- a hot metal transport container such as a hot metal ladle or a kneading car.
- the received hot metal is transported to a converter-type smelting furnace facility for performing dephosphorization treatment.
- the silicon content of the hot metal is high, for example, exceeding 0.40% by mass
- the silicon in the hot metal before the dephosphorization treatment is used for efficient dephosphorization treatment with a small amount of dephosphorization medium solvent. May be removed in advance (referred to as “hot metal desiliconization treatment”).
- the dephosphorization treatment can be efficiently performed even with
- the silicon removal treatment it is not necessary to perform the silicon removal treatment until the silicon content is less than 0.20% by mass, and the silicon content of the hot metal after the silicon removal treatment may be 0.20% by mass or more. .
- the silicon content of the hot metal is 0.40% by mass or less from the viewpoint of efficient dephosphorization treatment with a small amount of the dephosphorization medium solvent. That is, when performing desiliconization treatment, it is preferable to apply the dephosphorization treatment method of the present invention after reducing the silicon content of the hot metal to a range of 0.20 mass% to 0.40 mass%. .
- an oxygen source such as oxygen gas or iron oxide is supplied to the hot metal, the silicon in the hot metal is oxidized by these oxygen sources, and the silicon is oxidized (SiO 2 ).
- a method of forcibly removing can be used.
- Hot metal dephosphorization can be performed in a hot metal transfer container such as a hot metal ladle or a kneading car, but the converter-type smelting furnace has a larger freeboard than these hot metal transfer containers and vigorously stirs the hot metal. Therefore, the dephosphorization treatment can be performed quickly with a small amount of the dephosphorization medium solvent used. Therefore, in the present invention, dephosphorization is performed using a converter type refining furnace.
- FIG. 1 is a schematic diagram showing an example of a converter-type refining furnace suitable for carrying out the present invention.
- a converter-type refining furnace facility 1 includes a converter-type refining furnace 2 having an outer shell composed of an iron shell 3, and a refractory 4 applied to the inside of the iron shell 3.
- An upper blowing lance 5 that is inserted into the furnace type refining furnace 2 and is movable in the vertical direction is provided.
- a top 6 of the converter type refining furnace 2 is provided with a tap 6 for pouring the molten iron 18 after the dephosphorization process, and a gas for stirring is provided at the bottom of the converter type refining furnace 2.
- a bottom blowing tuyere 7 is provided. The bottom blowing tuyere 7 is connected to a gas introduction pipe (not shown).
- a hood 8 for collecting exhaust gas generated from the converter type refining furnace 2 is provided above the converter type refining furnace 2, and various refining agents are put into the converter type refining furnace 2.
- a raw material addition device 9 is installed.
- this raw material addition apparatus 9 for example, a hopper 10, a cutting apparatus 11 installed in the lower part of the hopper 10, a raw material supply apparatus including a chute 12 that is connected to the cutting apparatus 11 and penetrates the hood 8 is used. Can do.
- FIG. 1 only one hopper 10 that stores iron oxide 21 such as iron ore is illustrated, but actually, a plurality of hoppers are installed.
- An oxygen gas supply pipe 13 for supplying oxygen gas for dephosphorization and refining (industrial pure oxygen gas) and cooling water for cooling the upper blow lance 5 are supplied to and discharged from the upper blowing lance 5.
- a cooling water supply / drain pipe (not shown) is connected.
- the oxygen gas supply pipe 13 branches into a medium solvent supply pipe 14 on the way, and the medium solvent supply pipe 14 passes through the dispenser 17 and then joins the oxygen gas supply pipe 13 again.
- the dispenser 17 contains a powdery dephosphorization medium solvent mainly composed of CaO such as quicklime (hereinafter referred to as “CaO-based dephosphorization medium solvent 20”), and was introduced into the dispenser 17.
- the oxygen gas functions as a carrier gas for the CaO-based dephosphorization medium solvent 20, and the CaO-based dephosphorization medium solvent 20 is blown together with the oxygen gas from the tip of the top blowing lance 5 toward the hot metal 18 in the furnace. It is configured.
- the CaO-based dephosphorization medium solvent 20 is added to a collision position (referred to as “fire point”) between the oxygen gas and the hot metal bath surface.
- the oxygen gas supply pipe 13 is provided with a shutoff valve 15, and the medium solvent supply pipe 14 is provided with a shutoff valve 16. By opening and closing the shutoff valve 15 and the shutoff valve 16, only oxygen gas can be supplied into the furnace. It is configured as follows.
- a cold iron source such as iron scrap is charged into the converter type refining furnace 2, and then molten iron 18 is charged into the converter type refining furnace 2, and Ar gas, nitrogen gas, etc. are supplied from the bottom blowing tuyere 7. While blowing the inert gas as a stirring gas, the CaO-based dephosphorization medium solvent 20 is blown and added to the hot metal 18 together with the oxygen gas from the top blowing lance 5, and the hot metal 18 in the furnace is dephosphorized. . In that case, you may add the iron oxide 21 on the hot metal bath surface from the raw material addition apparatus 9 as needed.
- Phosphorus contained in the hot metal 18 is oxidized by oxygen gas to become phosphor oxide (P 2 O 5 ), and 3CaO is added to the slag 19 formed by the incubation of the CaO-based dephosphorization medium solvent 20 added to the furnace.
- ⁇ P 2 O 5 is fixed as ( "Ca 3 (PO 4) 2" also referred to as a) a stable form of the compound, the dephosphorization reaction of molten iron 18 progresses.
- the iron oxide 21 not only functions as a hatching accelerator for the CaO-based dephosphorization medium 20, but also has a function of increasing the oxygen potential of the slag 19 and increasing the dephosphorization ability of the slag 19.
- the dephosphorization reaction is promoted by the addition of.
- FeO is generated in the furnace by the oxygen gas supplied from the top blowing lance 5
- the addition of the iron oxide 21 is not an essential condition in the present invention.
- the present inventors supply from the top blowing lance 5 for the purpose of efficiently performing the dephosphorization process even when the silicon content of the hot metal 18 is high.
- the oxygen gas supplied from the top blowing lance 5 is also consumed in the removal reaction of silicon contained in the molten iron 18 (referred to as “desiliconization reaction”).
- the desiliconization period the period in which the desiliconization reaction in the early stage of refining takes precedence is called the “desiliconization period”, and the subsequent period is sometimes distinguished from the “dephosphorization period”.
- the oxygen gas excluding the portion used for the desiliconization reaction out of the oxygen gas supplied to the furnace is degassed. It was defined as "extrasilicic oxygen”.
- extrasilicic oxygen the ratio between the amount of CaO (kg / molten iron-ton) and the amount of oxygen outside desiliconization (kg / molten iron-ton) in the CaO-based dephosphorization medium solvent sprayed from the top blowing lance 5 onto the molten iron bath surface
- the amount of the ratio [CaO amount / oxygen concentration outside desiliconization] on the dephosphorization reaction was investigated by varying the amount of CaO / oxygen amount outside desiliconization].
- the ratio [CaO amount / deoxygenation outside oxygen amount] is also simply referred to as “CaO / O”.
- FIG. 2 is a graph showing the relationship between the ratio [CaO amount / oxygen content outside desiliconization] and dephosphorization lime efficiency.
- the dephosphorizing lime efficiency means that when the hot metal 18 is dephosphorized by adding the same amount of CaO in the CaO-based dephosphorization medium solvent, among the added CaO, 3CaO ⁇ P 2 O 5 The mass ratio of the CaO component forming the compound is expressed as a percentage.
- the CaO-based dephosphorization medium 20 In the region where the ratio [CaO amount / deoxygenation outside oxygen amount] is less than 0.90 and the dephosphorization lime efficiency is hardly lowered, if the CaO-based dephosphorization medium 20 is supplied into the furnace, the supplied CaO-based solution
- the dephosphorization medium solvent 20 can contribute to the dephosphorization reaction at a certain ratio.
- the region where the ratio [CaO amount / oxygen concentration outside desiliconization] is less than 0.90 is a region where the dephosphorization amount increases as the addition amount of the CaO-based dephosphorization medium solvent 20 is increased.
- the ratio [CaO amount / desiliconized oxygen outside the range is such that the CaO-based dephosphorization medium solvent 20 can effectively contribute to the dephosphorization reaction. It was found that the specific value was less than 0.90. In this range, a larger amount of the CaO-based dephosphorization medium solvent 20 is advantageous for increasing the dephosphorization amount and lowering the phosphorus content of the hot metal, so the ratio [CaO amount / desiliconization].
- the amount of external oxygen] is preferably 0.6 or more, more preferably 0.80 or more.
- the present invention is based on the above knowledge, and the dephosphorization treatment method for the hot metal 18 in the converter type refining furnace 2 according to the present invention blows oxygen gas from the top blowing lance 5 to the hot metal 18 in the converter type refining furnace.
- the CaO-based dephosphorization medium 20 is sprayed onto the collision surface of the oxygen gas to the hot metal 18 through the upper blowing lance 5 to oxidize phosphorus in the hot metal with the oxygen gas,
- the hot metal 18 having a silicon content of 0.20% by mass or more before the dephosphorization treatment is dephosphorized.
- the ratio of the amount of CaO (kg / molten iron-ton) in the CaO-based dephosphorization medium solvent sprayed from the top blowing lance 5 onto the molten iron bath surface and the amount of oxygen outside desiliconization (kg / molten iron-ton) [ CaO amount / desiliconized oxygen amount] is less than 0.90 So as to, and adjusts the amount of CaO-type dephosphorization for medium solvent 20 added blown from the top lance 5 in accordance with the de- ⁇ oxygen.
- the oxygen gas amount of 1 Nm 3 / molten iron-ton corresponds to the oxygen addition amount of 1.43 kg / molten iron-ton, in order to desiliconize 1 kg of silicon.
- the total amount of oxygen gas or the amount of oxygen outside desiliconization is determined by determining the total amount of oxygen gas so as to satisfy the thermal conditions from the hot metal temperature, the amount of scrap used, the silicon content in the hot metal before processing, etc.
- the amount of oxygen outside desiliconized necessary for dephosphorization is determined empirically from the previous phosphorus content in the hot metal and the target phosphorus content in the hot metal.
- the ratio of the top blowing rate (kg / min) of pure CaO to the mass flow rate (kg / min) of oxygen gas is used as an index, and the [CaO amount / desorption of the present invention].
- the mass flow rate of the former oxygen gas also includes oxygen consumed in the desiliconization reaction, so when the silicon content of the hot metal before the treatment increases, In the former case, the CaO supply amount in the entire dephosphorization process tends to be excessive.
- the CaO supply amount does not become excessive.
- the dephosphorization treatment method of the present invention is preferably applied to the dephosphorization treatment of hot metal having a silicon content before treatment of 0.20% by mass or more, more preferably 0.25% by mass or more.
- the CaO-based dephosphorization medium solvent 20 used in the present invention can be used regardless of the type as long as it is a substance containing 50% by mass or more of CaO.
- quick lime, calcium carbonate, dolomite and the like are used. be able to.
- Those mixed with iron oxide, fluorite, alumina, converter slag (slag generated by decarburization refining in hot metal converter), etc. are also used as a dephosphorization medium solvent 20 mainly composed of CaO. can do.
- the CaO pure content of quicklime is about 90 to 96% by mass.
- most of the CaO source used in the dephosphorization treatment is desirably the powdered CaO-based dephosphorization medium solvent 20 supplied from the top blowing lance 5.
- a known CaO source such as granular quicklime or crushed steelmaking slag at the beginning of the dephosphorization treatment (a period until 1/3 of the planned dephosphorization time elapses) is not prevented.
- the usage amount of the CaO source other than the CaO-based dephosphorization medium solvent supplied from the top blowing lance 5 is increased, the supply amount of the CaO-based dephosphorization medium solvent to the fire point for promoting the dephosphorization reaction is increased.
- the usage amount of the CaO source other than the CaO-based dephosphorization medium solvent supplied from the top blowing lance 5 is about 1/4 or less, more preferably less than 1/5 of the total usage amount of the CaO source in terms of CaO. It is desirable to keep it.
- CaO sources other than the CaO-based dephosphorization medium solvent supplied from the top blowing lance 5 are supplied via the chute 12.
- the hot metal 18 is dephosphorized by controlling the ratio [CaO amount / external oxygen amount of desiliconization] to be less than 0.90, but the silicon content of the hot metal 18 before dephosphorization treatment is 0.00. In the case of 30% by mass or more, as shown in FIG. 3, as the silicon content increases, the dephosphorization amount decreases, and the phosphorus concentration in the hot metal after the dephosphorization treatment tends to exceed 0.035% by mass. It was.
- FIG. 3 shows a hot metal having a phosphorus concentration of 0.100 to 0.120% by mass and a hot metal temperature of 1280 to 1300 ° C.
- the amount of oxygen outside desiliconization is 11 to 13 Nm 3 / hot metal-ton.
- the hot metal temperature at the end of the dephosphorization process is controlled to be 1350 to 1370 ° C., and the dephosphorization process is performed by applying the present invention. It is a figure which shows the investigation result of the relationship between the silicon concentration in the hot metal before a dephosphorization process, and the phosphorus concentration in the hot metal after a dephosphorization process.
- the silicon content of the hot metal before the dephosphorization treatment is less than 0.30% by mass
- the phosphorus concentration in the hot metal after the dephosphorization treatment is stabilized to 0.035% by mass. It is confirmed that the following can be made.
- CaO in the CaO-based dephosphorization medium solvent is considered to generate a compound in the form of SiO 2 and CaO ⁇ SiO 2 (calcium silicate) produced by oxidation of silicon. Therefore, the reason why the amount of dephosphorization decreases when the hot metal having a silicon concentration of 0.30% by mass or more is consumed when the hot metal having a silicon concentration of 0.30% by mass or more is dephosphorized to produce CaO.SiO 2.
- CaO amount increases as compared with the case of the dephosphorization of low silicon concentration molten iron, when CaO is subjected to generation of 3CaO ⁇ P 2 O 5 becomes stable form of the compound is due to the relatively small Conceivable.
- the present inventors added CaO-based dephosphorization medium solvent 20 without excess and deficiency when dephosphorizing hot metal 18 having a silicon concentration of 0.30% by mass or more, and efficiently performing dephosphorization treatment.
- CaO obtained by removing CaO content used to produce CaO.SiO 2 (calcium silicate) from CaO supplied into the furnace as a CaO source such as the CaO-based dephosphorization medium solvent 20 is “ It was defined as “desiliconized CaO”.
- CaO supplied into the furnace is a combination of CaO contained in the CaO-based dephosphorization medium solvent 20 supplied from the top blowing lance 5 and CaO contained in the CaO source supplied from the chute 12.
- the SiO 2 source for producing CaO ⁇ SiO 2 includes SiO 2 contained in an additive material such as slag in addition to SiO 2 produced by the desiliconization reaction of hot metal.
- the CaO content that contributes to the dephosphorization reaction is CaO outside desiliconization
- the conventional knowledge suggests that the amount of dephosphorization increases as the CaO outside desiliconization increases.
- the dephosphorization behavior is changed by changing the ratio [CaO amount / outside silicon removal oxygen amount] even if the amount outside Ca removal is the same.
- FIG. 4 shows a case where the ratio [CaO amount / oxygen concentration outside desiliconization] is less than 0.70.
- FIG. 5 shows a case where the ratio [CaO amount / oxygen amount outside silicon removal] is 0.70 or more and less than 0.80.
- FIG. 6 shows that when the ratio [CaO amount / oxygen outside the silicon removal] is 0.80 or more and less than 0.90,
- FIG. 7 shows that the ratio [CaO amount / oxygen outside the silicon removal] is 0.90 or more and 1.00.
- T. CaO is the total amount of CaO in the added CaO-based dephosphorization medium solvent.
- the ratio [CaO amount / oxygen concentration outside desiliconization] is 0.80 or more and less than 0.90, as shown in FIG. 6, the desiliconization outside CaO is in the vicinity of 9 kg / molten iron-ton. Until then, the amount of dephosphorization increases with the increase in non-silicon removal CaO, but when the amount of non-silicon removal CaO exceeds 9 kg / molten-ton, the increase in dephosphorization is negligible and the increase in non-silicon removal CaO is It was found that it was not effective in increasing the amount of dephosphorization.
- the CaO-based dephosphorization medium 20 is added so that the non-silicon removal CaO exceeds 9 kg / molten-ton. Even so, the amount of CaO added exceeding 9 kg / molten iron-ton is an excess amount without contributing to the dephosphorization reaction. On the contrary, lowering of the molten iron temperature or incubation of the CaO-based dephosphorization solvent 20 is caused. It was proved that the dephosphorization reaction could be inhibited instead.
- the hot metal having a silicon concentration of 0.30% by mass or more is dephosphorized, when the ratio [CaO amount / oxygen concentration outside desiliconization] is less than 0.80, CaO2 outside desiliconization Since the amount of dephosphorization increases with the addition of C, it is preferable to increase the amount of CaO outside desiliconization within a temperature margin, and the effective amount of dephosphorization is 8 kg / molten iron-ton or more. It is suitable for ensuring the above.
- the ratio of the amount of CaO in the CaO-based dephosphorization medium solvent added from the top blowing lance 5 to the amount of oxygen outside desiliconized [CaO amount / the amount of oxygen outside desiliconized]
- the dephosphorization amount increases as the CaO concentration in the slag increases. Since the hot metal 18 is dephosphorized under the operating conditions, the added CaO-based dephosphorization solvent 20 efficiently absorbs the produced phosphorous oxide (P 2 O 5 ). In comparison, it is possible to perform the dephosphorization treatment more efficiently.
- Example 1 Using the converter type smelting furnace equipment shown in FIG. 1, the present invention was applied to the hot metal discharged from the blast furnace to perform the dephosphorization treatment.
- the phosphorus concentration in the hot metal before the dephosphorization treatment is 0.100 to 0.120% by mass
- the silicon concentration in the hot metal is 0.20% by mass to less than 0.30% by mass
- the hot metal temperature is 1280 to 1300 ° C.
- the amount of oxygen outside desiliconization is 15.7 to 17.2 kg / molten iron-ton (11 to 12 Nm 3 / molten metal-ton) so that the molten iron temperature at the end of the dephosphorization treatment is 1350 to 1370 ° C. did.
- the total amount of CaO-based dephosphorization medium solvent is determined from the amount of oxygen outside desiliconization by setting the ratio [CaO amount / outside silicon removal amount] in the range of 0.83 to 0.85, and the addition rate is made constant.
- the dephosphorization treatment was performed by spraying a CaO-based dephosphorization medium solvent from the top blowing lance (Example 1 of the present invention).
- the source of CaO added to the furnace is only the CaO-based dephosphorization medium solvent sprayed from the top blowing lance, and the ratio [CaO amount / oxygenated oxygen outside the siliconized non-siliconized CaO is 9 kg / molten-ton or less. Amount] was adjusted.
- As the CaO-based dephosphorization medium solvent quick lime (CaO pure content: 93% by mass) was used.
- FIG. 8 shows the relationship between the carbon concentration in the hot metal after the dephosphorization treatment and the phosphorus concentration in the hot metal when the present invention is applied to perform the dephosphorization treatment (Example 1 of the present invention).
- the relationship between the carbon concentration in the hot metal after the dephosphorization treatment and the phosphorus concentration in the hot metal in the conventional dephosphorization treatment is also shown as Conventional Example 1.
- the addition rate of the CaO-based dephosphorization medium solvent is set to 1.67 kg / (min ⁇ molten-ton) from the initial stage to the middle stage of the dephosphorization treatment including the desiliconization period, with a pure CaO content.
- the oxygen supply rate is 1.94 to 2.50 Nm 3 / (min ⁇ molten-ton) in the desiliconization period and 1.33 Nm 3 / (min in the dephosphorization period. -Hot metal-ton), and the blowing time was about 12 minutes.
- the ratios [CaO amount / deoxygenation outside oxygen amount] in Conventional Example 1 are all 1.00 or more, and the basicity of slag after dephosphorization treatment ((mass% CaO) / (mass% SiO 2 )) is The range was 2.7 to 3.7.
- the solid line shows the regression equation by power approximation in Example 1 of the present invention obtained using the least square method
- the broken line shows the regression equation by power approximation in Conventional Example 1 obtained by using the least square method. Indicates.
- the dephosphorization treatment is performed with the ratio [CaO amount / out-silicon removal oxygen amount] being less than 0.90, the dephosphorization lime efficiency is improved, and the CaO-based dephosphorization medium solvent is efficiently used.
- the phosphorus concentration in the hot metal after the dephosphorization treatment is 0.030% by mass or less as shown in FIG. It was realized that the medium phosphorus concentration was stabilized at a low level.
- Conventional Example 1 has a ratio [CaO amount / deoxygenation outside oxygen amount] of 1.00 or more, and the dephosphorization lime efficiency is low, and the CaO-based dephosphorization medium solvent is efficiently used for dephosphorylation. It is considered that the phosphorous concentration in the hot metal after the dephosphorization treatment was increased by this.
- Example 2 When the silicon concentration in the hot metal was higher than 0.30% by mass and lower than 0.50% by mass than the inventive example 1, dephosphorization treatment was performed by applying the present invention.
- the hot metal components other than silicon and the conditions of the hot metal temperature were the same as in Example 1 of the present invention.
- the silicon content in the hot metal increased, the amount of oxygen outside desiliconization was increased to 16.7 to 19.5 kg / molten metal-ton (11.7 to 13.7 Nm 3 / molten metal-ton).
- the ratio [CaO amount / oxygen concentration outside desiliconization] is in the range of 0.75 or more and less than 0.90
- the ratio [CaO amount / oxygen concentration outside desiliconization] is 0.80 or more and less than 0.90
- the silica outer CaO is in the range of 6-9 kg / molten iron-ton and the ratio [CaO amount / deoxygenated oxygen amount] is 0.75 or more and less than 0.80
- the desiliconized CaO is 8 kg / molten iron.
- the total amount of CaO-based dephosphorization medium solvent is determined from the amount of oxygen outside the desiliconization so that the amount of oxygen is more than -ton, and quick lime is used as the CaO-based dephosphorization medium solvent from the top blowing lance so that the addition rate is constant.
- the phosphorous removal treatment was performed by spraying (CaO pure content 93 mass%) (Example 2 of the present invention).
- the source of CaO added to the furnace was only the CaO-based dephosphorization medium solvent sprayed from the top blowing lance, and the non-silicaized CaO was in the range of 8 to 9.6 kg / molten iron-ton.
- the hot metal dephosphorization method described in Patent Document 4 was applied to perform hot metal dephosphorization treatment in which the silicon concentration in the hot metal was 0.30 mass% or more and less than 0.50 mass%.
- the source of CaO added to the furnace is only the CaO-based dephosphorization medium solvent sprayed from the top spray lance, and the top spray rate (kg / min) of pure CaO and the mass flow rate (kg / min) of oxygen gas.
- the upper blowing rate of the pure CaO content was determined so that the ratio value was in the range of “0.56 + 0.69 ⁇ [Si] to 0.56 + 0.83 ⁇ [Si]”.
- the amount of oxygen outside desiliconization is in the range of 18.2 to 22.5 kg / molten-ton, and as a result, 0.96 to 1.2.
- desiliconized CaO is in the range of 11-17 kg / molten iron-ton, and the basicity of slag after dephosphorization treatment ((mass% CaO) / (mass% SiO 2 )) is 2.4-2. .6 range.
- FIG. 9 shows the relationship between the silicon concentration in the hot metal before the dephosphorization treatment and the amount of CaO used in the dephosphorization treatment in comparison between the present invention example 2 and the conventional example 2.
- FIG. 10 shows the relationship between the silicon concentration in the hot metal before the dephosphorization treatment and the dephosphorization amount of the hot metal in the dephosphorization treatment in comparison between Example 2 of the present invention and Conventional Example 2.
- Example 2 of the present invention even if the silicon concentration in the hot metal is as high as 0.30% by mass or more, the dephosphorization treatment can be carried out without significantly increasing the amount of CaO used as in Conventional Example 2. Recognize.
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Abstract
Description
[1]転炉型精錬炉内の溶銑に上吹きランスから酸素ガスを吹き付けるとともに、CaOを主成分とする脱燐用媒溶剤を前記酸素ガスの溶銑への衝突面に前記上吹きランスを介して吹き付け、前記酸素ガスによって溶銑中の燐を酸化し、生成した燐酸化物を滓化した前記脱燐用媒溶剤中に取り込むことにより溶銑中の燐を除去する脱燐処理方法において、脱燐処理前の珪素含有量が0.20質量%以上の溶銑を脱燐処理するにあたり、炉内に供給される酸素ガスのうちで脱珪反応に使用される分を除いた酸素ガスを脱珪外酸素量(kg/溶銑-ton)と定義したとき、上吹きランスから溶銑浴面に吹き付け添加する、CaOを主成分とする脱燐用媒溶剤中のCaO量(kg/溶銑-ton)と、前記脱珪外酸素量との比[CaO量/脱珪外酸素量]が0.90未満になるように、脱珪外酸素量に応じて上吹きランスから吹き付け添加する前記脱燐用媒溶剤の添加量を調整する、溶銑の脱燐処理方法。
[2]前記比[CaO量/脱珪外酸素量]を0.80以上0.90未満の範囲内とする、上記[1]に記載の溶銑の脱燐処理方法。
[3]脱燐処理前の珪素含有量が0.30質量%以上の溶銑を脱燐処理するにあたり、炉内に供給されるCaOのうちでCaO・SiO2(カルシウムシリケート)を生成するために使用されるCaO分を除いたCaOを脱珪外CaOと定義したとき、前記比[CaO量/脱珪外酸素量]を0.80以上0.90未満の範囲内として溶銑を脱燐処理する場合には、前記脱珪外CaOが6~9kg/溶銑-tonの範囲内になるように、上吹きランスから吹き付け添加する、CaOを主成分とする脱燐用媒溶剤の添加量を調整し、前記比[CaO量/脱珪外酸素量]を0.80未満の範囲として溶銑を脱燐処理する場合には、前記脱珪外CaOが8kg/溶銑-ton以上になるように、上吹きランスから吹き付け添加する、CaOを主成分とする脱燐用媒溶剤の添加量を調整する、上記[1]に記載の溶銑の脱燐処理方法。 The gist of the present invention for solving the above problems is as follows.
[1] Oxygen gas is blown from the top blowing lance to the hot metal in the converter-type refining furnace, and a dephosphorization medium solvent mainly composed of CaO is passed through the upper blowing lance to the collision surface of the oxygen gas with the hot metal. In the dephosphorization treatment method, the phosphorus in the hot metal is removed by oxidizing the phosphorus in the hot metal with the oxygen gas and taking the generated phosphor oxide into the hatched dephosphorization medium solvent. When dephosphorizing the hot metal having a silicon content of 0.20% by mass or more, the oxygen gas excluding the portion used for the desiliconization reaction out of the oxygen gas supplied into the furnace is deoxygenated outside oxygen. When the amount (kg / molten-ton) is defined, the amount of CaO (kg / molten-ton) in the dephosphorization medium solvent containing CaO as a main component added by spraying from the top blowing lance to the molten iron bath surface, The ratio [CaO amount / outside silicon removal amount] with the outside silicon removal amount To be less than .90, adjusting the addition amount of the medium solvent for dephosphorization is added blown from the top lance according to de 珪外 oxygen, dephosphorization method hot metal.
[2] The hot metal dephosphorization method according to the above [1], wherein the ratio [CaO amount / desiliconized oxygen amount] is in the range of 0.80 or more and less than 0.90.
[3] In order to produce CaO.SiO 2 (calcium silicate) among the CaO supplied to the furnace in dephosphorizing hot metal having a silicon content of 0.30% by mass or more before dephosphorization. When CaO excluding CaO used is defined as non-desiliconized CaO, the ratio [CaO amount / non-silicon oxide content] is set within a range of 0.80 or more and less than 0.90 to dephosphorize the hot metal. In this case, the addition amount of the dephosphorization medium solvent containing CaO as a main component and added by spraying from the top blowing lance is adjusted so that the CaO outside desiliconization is in the range of 6-9 kg / molten-ton. When the hot metal is dephosphorized with the ratio [CaO amount / oxygen concentration outside desiliconization] in the range of less than 0.80, the top blown so that the non-desiliconization CaO is 8 kg / molten iron-ton or more. Dephosphorization with CaO as main component, sprayed from lance Adjusting the addition amount of the solvent, dephosphorization method hot metal according to the above [1].
脱珪外酸素量(kg/溶銑-ton)=F0×1.43-脱珪用酸素量(kg/溶銑-ton) …(2)
CaO量(kg/溶銑-ton)=脱珪外酸素量(Nm3/溶銑-ton)×([CaO/O]の値) …(3)
ここで、酸素ガス総量或いは脱珪外酸素量は、溶銑温度、スクラップ使用量、処理前の溶銑中珪素含有量などから熱的な条件を満たすように酸素ガス総量を決定するか、または、処理前の溶銑中燐含有量、目標とする溶銑中燐含有量などから経験的に脱燐のために必要とする脱珪外酸素量を決定するようにする。 Oxygen amount for desiliconization (kg / molten-ton) = (Z / 100) × 1000 × 1.142 (1)
Desiliconized oxygen content (kg / molten metal-ton) = F 0 × 1.43-Desiliconized oxygen content (kg / molten metal-ton) (2)
CaO amount (kg / molten metal-ton) = Desiliconized oxygen content (Nm 3 / molten metal-ton) × (value of [CaO / O]) (3)
Here, the total amount of oxygen gas or the amount of oxygen outside desiliconization is determined by determining the total amount of oxygen gas so as to satisfy the thermal conditions from the hot metal temperature, the amount of scrap used, the silicon content in the hot metal before processing, etc. The amount of oxygen outside desiliconized necessary for dephosphorization is determined empirically from the previous phosphorus content in the hot metal and the target phosphorus content in the hot metal.
図1に示す転炉型精錬炉設備を用い、高炉から出銑された溶銑に対して本発明を適用して脱燐処理を実施した。脱燐処理前の溶銑中燐濃度は0.100~0.120質量%、溶銑中珪素濃度は0.20質量%以上0.30質量%未満、溶銑温度は1280~1300℃であり、この溶銑に対して、脱燐処理終了時の溶銑温度が1350~1370℃となるように、脱珪外酸素量を15.7~17.2kg/溶銑-ton(11~12Nm3/溶銑-ton)とした。比[CaO量/脱珪外酸素量]を0.83~0.85の範囲として、脱珪外酸素量からCaO系脱燐用媒溶剤の総使用量を決定し、添加速度を一定とするように上吹きランスからCaO系脱燐用媒溶剤を吹き付けて脱燐処理を行った(本発明例1)。炉内に添加したCaO源は上吹きランスから吹き付けたCaO系脱燐用媒溶剤のみであり、脱珪外CaOが9kg/溶銑-ton以下となるように、比[CaO量/脱珪外酸素量]を調整した。CaO系脱燐用媒溶剤としては生石灰(CaO純分93質量%)を使用した。 [Example 1]
Using the converter type smelting furnace equipment shown in FIG. 1, the present invention was applied to the hot metal discharged from the blast furnace to perform the dephosphorization treatment. The phosphorus concentration in the hot metal before the dephosphorization treatment is 0.100 to 0.120% by mass, the silicon concentration in the hot metal is 0.20% by mass to less than 0.30% by mass, and the hot metal temperature is 1280 to 1300 ° C. On the other hand, the amount of oxygen outside desiliconization is 15.7 to 17.2 kg / molten iron-ton (11 to 12 Nm 3 / molten metal-ton) so that the molten iron temperature at the end of the dephosphorization treatment is 1350 to 1370 ° C. did. The total amount of CaO-based dephosphorization medium solvent is determined from the amount of oxygen outside desiliconization by setting the ratio [CaO amount / outside silicon removal amount] in the range of 0.83 to 0.85, and the addition rate is made constant. Thus, the dephosphorization treatment was performed by spraying a CaO-based dephosphorization medium solvent from the top blowing lance (Example 1 of the present invention). The source of CaO added to the furnace is only the CaO-based dephosphorization medium solvent sprayed from the top blowing lance, and the ratio [CaO amount / oxygenated oxygen outside the siliconized non-siliconized CaO is 9 kg / molten-ton or less. Amount] was adjusted. As the CaO-based dephosphorization medium solvent, quick lime (CaO pure content: 93% by mass) was used.
本発明例1よりも溶銑中珪素濃度が高い0.30質量%以上0.50質量%未満の場合に、本発明を適用して脱燐処理を行った。珪素以外の溶銑成分及び溶銑温度の条件は本発明例1と同様であった。溶銑中珪素含有量の増大に伴って、脱珪外酸素量は16.7~19.5kg/溶銑-ton(11.7~13.7Nm3/溶銑-ton)に増大させた。 [Example 2]
When the silicon concentration in the hot metal was higher than 0.30% by mass and lower than 0.50% by mass than the inventive example 1, dephosphorization treatment was performed by applying the present invention. The hot metal components other than silicon and the conditions of the hot metal temperature were the same as in Example 1 of the present invention. As the silicon content in the hot metal increased, the amount of oxygen outside desiliconization was increased to 16.7 to 19.5 kg / molten metal-ton (11.7 to 13.7 Nm 3 / molten metal-ton).
2 転炉型精錬炉
3 鉄皮
4 耐火物
5 上吹きランス
6 出湯口
7 底吹き羽口
8 フード
9 原料添加装置
10 ホッパー
11 切出装置
12 シュート
13 酸素ガス供給管
14 媒溶剤供給管
15 遮断弁
16 遮断弁
17 ディスペンサー
18 溶銑
19 スラグ
20 CaO系脱燐用媒溶剤
21 酸化鉄 DESCRIPTION OF SYMBOLS 1 Converter type
Claims (3)
- 転炉型精錬炉内の溶銑に上吹きランスから酸素ガスを吹き付けるとともに、CaOを主成分とする脱燐用媒溶剤を前記酸素ガスの溶銑への衝突面に前記上吹きランスを介して吹き付け、前記酸素ガスによって溶銑中の燐を酸化し、生成した燐酸化物を滓化した前記脱燐用媒溶剤中に取り込むことにより溶銑中の燐を除去する脱燐処理方法において、
脱燐処理前の珪素含有量が0.20質量%以上の溶銑を脱燐処理するにあたり、炉内に供給される酸素ガスのうちで脱珪反応に使用される分を除いた酸素ガスを脱珪外酸素量(kg/溶銑-ton)と定義したとき、上吹きランスから溶銑浴面に吹き付け添加する、CaOを主成分とする脱燐用媒溶剤中のCaO量(kg/溶銑-ton)と、前記脱珪外酸素量との比[CaO量/脱珪外酸素量]が0.90未満になるように、脱珪外酸素量に応じて上吹きランスから吹き付け添加する前記脱燐用媒溶剤の添加量を調整する、溶銑の脱燐処理方法。 The oxygen gas is blown from the top blowing lance to the hot metal in the converter type refining furnace, and the dephosphorization medium solvent mainly composed of CaO is blown to the collision surface of the oxygen gas with the hot metal through the top blowing lance. In the dephosphorization treatment method of removing phosphorus in hot metal by oxidizing the phosphorus in hot metal with the oxygen gas and incorporating the generated phosphor oxide into the dephosphorization medium solvent which has been hatched,
When dephosphorizing hot metal having a silicon content of 0.20% by mass or more before the dephosphorization treatment, the oxygen gas excluding the portion used for the desiliconization reaction out of the oxygen gas supplied into the furnace is removed. The amount of CaO in the dephosphorization medium solvent containing CaO as the main component (kg / molten metal-ton) added by spraying from the top blowing lance onto the molten metal bath surface when defined as the amount of oxygen outside the silica (kg / molten-ton) And dephosphorization by adding from the top blowing lance according to the amount of oxygen outside the silicon removal so that the ratio [CaO amount / the amount of oxygen outside the silicon removal] is less than 0.90. A method for dephosphorizing hot metal by adjusting the amount of solvent added. - 前記比[CaO量/脱珪外酸素量]を0.80以上0.90未満の範囲内とする、請求項1に記載の溶銑の脱燐処理方法。 2. The hot metal dephosphorization method according to claim 1, wherein the ratio [CaO amount / deoxygenation outside oxygen amount] is within a range of 0.80 or more and less than 0.90.
- 脱燐処理前の珪素含有量が0.30質量%以上の溶銑を脱燐処理するにあたり、炉内に供給されるCaOのうちでCaO・SiO2(カルシウムシリケート)を生成するために使用されるCaO分を除いたCaOを脱珪外CaOと定義したとき、
前記比[CaO量/脱珪外酸素量]を0.80以上0.90未満の範囲内として溶銑を脱燐処理する場合には、前記脱珪外CaOが6~9kg/溶銑-tonの範囲内になるように、上吹きランスから吹き付け添加する、CaOを主成分とする脱燐用媒溶剤の添加量を調整し、
前記比[CaO量/脱珪外酸素量]を0.80未満の範囲として溶銑を脱燐処理する場合には、前記脱珪外CaOが8kg/溶銑-ton以上になるように、上吹きランスから吹き付け添加する、CaOを主成分とする脱燐用媒溶剤の添加量を調整する、請求項1に記載の溶銑の脱燐処理方法。 Used to produce CaO.SiO 2 (calcium silicate) among the CaO supplied into the furnace when dephosphorizing hot metal having a silicon content of 0.30% by mass or more before dephosphorization. When CaO excluding CaO is defined as non-siliconized CaO,
When hot metal is dephosphorized with the ratio [CaO content / oxygen concentration outside desiliconization] in the range of 0.80 or more and less than 0.90, the range of the above desiliconization CaO is 6-9 kg / molten iron-ton. Adjust the addition amount of the dephosphorization medium solvent containing CaO as a main component to be added by spraying from the top blowing lance so as to be inside.
When the hot metal is dephosphorized by setting the ratio [CaO amount / oxygen concentration outside desiliconization] to a range of less than 0.80, the top blowing lance is adjusted so that the non-silicon removal CaO is 8 kg / molten iron-ton or more. The hot metal dephosphorization treatment method according to claim 1, wherein the addition amount of the dephosphorization medium solvent containing CaO as a main component is adjusted by spraying.
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KR101748519B1 (en) | 2017-06-16 |
JPWO2015011910A1 (en) | 2017-03-02 |
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TWI568856B (en) | 2017-02-01 |
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