JPS6119715A - Refining method of molten iron - Google Patents

Abstract

PURPOSE:To refine molten iron efficiently and at low cost by a method wherein a necessary amount of reaction of each component of molten iron is determined from measured quantities of components thereof and the temperature and each relative value of the molten iron, slag and O2 is estimated so as to control the conditions of employment of a reaction agent and a carrier gas. CONSTITUTION:A necessary amount of reaction of each component of molten iron is determined from a measured quantity of each component and a measured temperature is relation to a target quantity of each component of the molten iron, a target temperature and a target process time. Meanwhile, prescribed relationships between the molten iron and slag, O2 and the slag, and the molten iron and O2, are determined by using as parameters the kind of a reaction agent and the amount and depth of injection thereof, the kind of a carrier gas and the amount of injection thereof, the measured quantity of each component of the molten iron, the measured temperature and measured components of slag before processing, and based thereon, the amount of reaction of each component of the molten iron and the slag is estimated simultaneously. Then, the estimated value thus obtained is compared with the necessary amount of reaction determined previously, and refining is performed while one or two or more of the parameters of the kind of the injected reaction agent and the amount and depth of injection thereof, the kind of the carrier gas and the amount of injection thereof and the number of lances is controlled so that the difference between said estimated value and the necessary amount can be the minimum.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is effective for refining molten iron such as hot metal or molten steel, and more specifically, for a molten iron refining method in which a reactant is injected into the molten iron together with a carrier gas. This method provides a method that can be applied generally.

(Prior art and its problems) In recent years, preliminary treatment of hot metal and secondary treatment of molten steel have been actively adopted in order to reduce the refining load in the steelmaking process and to manufacture high-purity steel. For example, hot metal supplied to the steelmaking process is subjected to preliminary treatments such as desiliconization, dephosphorization, and desulfurization.
It is known that by setting all the components of hot metal to predetermined low values, it is possible to reduce the basic unit of various auxiliary raw materials and reduce slopping in the steelmaking process, making stable refining possible. It is also well known that high-purity steel can be manufactured at a minimum total cost by further performing secondary treatments such as desulfurization or dephosphorization on the molten steel tapped from the steelmaking process. Pre-treatment of the hot metal and secondary treatment of the molten steel (
This preliminary treatment and secondary treatment (hereinafter collectively referred to as molten iron refining) is performed using a reactive agent for desiliconization, desulfurization, dephosphorization, etc. as disclosed in JP-A No. 57-63610. This is generally carried out by so-called injection, in which a gas or an inert gas such as N2, Ar, or CO2 scum is injected into the molten iron as a carrier gas. In order to efficiently obtain the desired final component, it is necessary to appropriately control the amount, speed, type, etc. of the reactant and carrier gas in accordance with the conditions of the molten iron.

However, conventionally, the above control sets the amount and injection speed of the reactant empirically based on past results, performs sampling after injecting a predetermined amount of the reactant, and restarts the reaction again if the target value has not been reached. It was common practice to inject a chemical into the area for treatment. In addition, in the conventional method, there was no means to control each component of molten iron at the same time.
It was extremely difficult to achieve target values for multiple components at the same time, such as blood being outside the target value. For this reason, the achievement rate of the target components is extremely low, and there are also problems such as the processing time being extended and the temperature of the molten iron becoming lower than the target temperature.

(Objective of the Invention) The present invention provides a molten iron refining method in which a reactant is blown into the molten iron in the container together with a carrier gas, which achieves the maximum reaction efficiency and satisfies the allowable temperature drop, and which The purpose is to provide a method that can accurately achieve target values for each component.

(Structure of the Invention) In the method for refining molten iron, the present invention provides a method for refining molten iron, in which each target component of the molten iron is calculated from the target temperature T(h) and the actual measured amount of each component 1 for the target processing time t, and the actual measured temperature T1. In addition to determining the required reaction amount for each component, the type of reactant, the amount of blowing, the depth of blowing, the type of carrier gas, the amount of blowing, and the above Il of the molten iron.

T1, with the measured slag component before treatment as a parameter,
From the chemical equilibrium concentration at the reaction interface of molten iron and slag, the amount of movement of each component based on the concentration difference between molten iron and slag, and the 02 balance b between the slag, the movement speed to molten iron, and the air dissipation rate for the 02 supply rate. , the reaction amount of each component of molten iron and slag is estimated at the same time, and then the estimated reaction amount and the above-mentioned required reaction amount are compared, and the type and amount of the injected reactant are determined so that the difference is minimized. , blowing depth, type of carrier gas, blowing amount, and number of lances, or one or two of them.
A molten iron refining method characterized by refining while controlling three or more elements. In the above-mentioned refining method, the estimated reaction amount of each component between molten iron and slag, the reaction amount between the slag floating on the molten iron and the molten iron, and the reaction amount between the reaction particles floating in the molten iron and the molten iron, respectively. It is assumed that ``t-features'' are obtained by determining the characteristics of

The specific configuration of the present invention will be explained in detail below.

Now, refining reactions such as desiliconization, dephosphorization, and desulfurization of molten iron have conventionally been carried out using silicon in the molten iron and 02 (oxides, solid oxygen, and gas supplied to the molten iron), which are supplied to the molten iron. It was said that it was determined by the reaction with (including oxygen). or,
In the dephosphorization process, it was also determined by the reaction between phosphorus in molten iron and 02. However, the present inventors discovered that there is a big difference between the refining reactions such as the desiliconization reaction and the reactions in actual operations.As a result of repeated many experiments and research, the inventors found that in both refining reactions, the supply to molten iron 02 to be processed is not only a single component to be processed but also C(
carbon), Mn (manganese), Ti (titanium), P (phosphorus)
, St (silicon), RE (iron) and other components also cause competitive reaction sounds, and CaO (quicklime), which is supplied for the purpose of basicity adjustment, is S We found that not only the reactions of the components targeted for treatment, such as reacting at the same time as sulfur, but also the various reactions that occur in molten iron have a major influence.

Based on this knowledge, as a result of further experimental research, the present inventors discovered that the above-mentioned C, Mn1Si, P, S, Ti1Fe in the molten iron and the reactants such as 02 and CaO supplied in the molten iron.
(hereinafter these components are collectively referred to as each component in molten iron), we succeeded in quantitatively determining the competitive reactions that proceed simultaneously. First, we will explain the requirements for this competitive reaction.

The reactants supplied into the molten iron, for example, 02, CaO, cause the reactions shown in the following formulas (1) to (8) with each component in the molten iron, such as Oite, St1Mn%P, SS0%T1, etc., which proceed simultaneously. do.

St + 2 (0) = 8i02...Song interval (1)
Mn + (0) = MnO...Song (2)P
+2.5(0) ・PO2,5...(3)C+
(0) = ω ・・・・・・(4) Ti + 2(0)
TiO2...(5); F'e + (0)
= Fe0・1・1. ...1.0(6)Fe203
+ F'e = 31i'eO... (7) S + Ca
O = CaS + ”・, (0) ... (8) As a general method for estimating the reaction amount of each component in such reactions that proceed simultaneously, Example 1...E[8, can
The document published in Inject III Palt 1 (hereinafter referred to as known document) is publicly known. However, the method in this known document is limited to reactions (1), (3), (4), (6), and (8) of the reactions shown in formulas (1) to (8) above.
), and moreover, it is limited to the reaction between molten iron and slag in a static state, such as floating on top of molten iron. However, in actual refining of molten iron, Mn is one of the most controlled elements, and it is not acceptable for it not to meet the target value. Also, Ti
d It is an important element that affects the desiliconization efficiency in the desiliconization process, and failure to meet the target value is unacceptable.

In addition, most of the solid iron oxide source injected into the molten iron as a reactant contains Fe2O3, and the reaction caused by K cannot be ignored. Therefore, it is an essential condition that Mn1Ti and Fe2O3 are included in the refining reaction.

Furthermore, in the refining method of the present invention in which the reactant is injected together with a carrier gas, the reaction that occurs between the reactant and the molten iron while it floats in the molten iron has an important influence, and the type of reactant, the amount of injection, In order to control control requirements such as the blowing depth, the type of carrier gas, the blowing amount, and the number of lances, the reaction during the floating process of the reactant (hereinafter referred to as the transition reaction) is necessary. It is extremely important to know. In addition, the reactant floats in the molten iron, becomes slag on the molten iron, and reacts with the molten iron as slag (this reaction between the slag floating on the molten iron and the molten iron is hereinafter referred to as a permanent reaction). In addition to the reactions during the levitation process, it is also important to know the reactions after levitation.

Therefore, the present inventors have determined that the reactions shown in formulas (1) to (8) above proceed simultaneously, and the reaction while the reactant floats in the molten iron, that is, the transitory reaction, and the reaction after floating. As a result of further research on a method for comprehensively estimating the reaction, that is, the above-mentioned permanent reaction, we succeeded in developing a method for quantitatively estimating K as described above.

Now, the reaction rates shown in the above formulas (1) to (8) are sufficiently fast, and the rate-determining process for each reaction can be considered to be the movement of components to the molten iron side and the slag side.

Therefore, the movement speed Jk of each component due to the concentration gradient of each component on the molten iron side and the slag side (Sr is Bg Mn,
Ti% only F3b C,Q 8102. MnQPO
2,s, TiO2, Fed.

Each component of Fe20B and CaS is shown. ) f: can be expressed as equations (9) to (1?) using the double-layer theory in reaction engineering. By multiplying this Jh by the processing time and reaction area, the amount of movement of each component can be determined.

J8□=Fsi(%511)-%81s=FBio2
((%5i02)'(%5iO2)s)-<9)Jun
=FMn(%Mnb・%MnW')=FMno((%M
n0) bill (%Mn0)s)...αQJτ1=FT1(%
Tib-%Ti')=FTto2(%Ti02)"-(
ITiO2)')・41JP='FP(%Pb-%P Town=FP((%PO2,s) Town(%PO2,s)")
−・・42Jo=Fo(%C1・ChiC”)=Goo(P
oo'・1)・・・・・・Face JB=FB(%Sb-$
S town=F'aas((%Ca5)"-(%Ca5)8)
+++ 641Jo: F'o (%cb・4c")...
・・・・・・・・・・・・a! 9Jyeo=Fyeo(
(%F'eO)”-(%Fe0)B)-Jy*2o3-
aeJpe2o3=F'ye2o3((%F'ezOa
)"-(%Fe20a)8)--aη Here, Jc + moving speed of each component (mol, g-force) F
″1; Modified transfer coefficient of each component in hot metal (more M)
F′j i Modified transfer coefficient of each component in slag [mO
1/cR2/8A)・b.

%l, component concentration of molten iron [chi]q6 iS
, component concentration in slag [chi]%i, component concentration at reaction interface [chi]G□o; Co generation rate coefficient
[:mO1/lx2/B]Poo": Co partial pressure at the reaction interface (atm) Furthermore, Fi and Fjtd are given by the following formula (11, (11).

ρP; Density of floating particles (g/,;'') ρ8;
Density of slag (g/ca11) Mt, Mj+
Molecular weight of 1 or l component Cg7fno 1:1 while,
From chemical equilibrium at the reaction interface between slag and molten iron (a)
The formula 〜(Foundation) is established, and the equilibrium concentration of each component is found.

Est=(μ5i02)/4Si'・ag'%"=1
0+)Ct・Ms1o2・fst・KsVρs Pot rst
o2...(21EMn= (%Mn0)'/%Mn
"ag"% = 100 houses Ct9MMno warmfMn・KM
Jpθ・γMnO...(c)ETi: (%Ti0
2) “7%Ti”-ag”%”=100・CtjMT1
o2・fTi・KT1/ρ8φγTiO2・−inter-song m
EP= (%POz,s)'/%P"(ao"%)"
=100-CtjMPo2115・fPjKv/pB・
γF'2,5...Inter-song (2) EO=POgin C・ao
”%=fc・KO・・・・・・・(c)E B=
(%0a8)"a6'%/%S"(%Ca0)'=MO
&8＠fB＠γ0a01Ka/MO&O+γOa8・Shonchoshokyokuga EP1110= (%1'eO)"/a6"%
=100@CtIIMF・olaF・IK1r@vρs
・r Fe 0 - Between songs eAEFII203 = (%
Fe0)ν(%Fe20a)”3=MPeO°rye2
o3 “are ° 1r@, 03/Mye2o3 @
rp*o -el) However, Ct, molar concentration [mO1/cIft3]
f1; Activity coefficient of l component γ1; Activity coefficient Ki of l component in slag;
Thermodynamic equilibrium constant of the l component aFe; Activity of Fe El; Modified thermodynamic equilibrium constant of the l component Also, the total supply rate of 02 supplied from the reactant and carrier gas, etc., and the slag, molten iron, etc. The following 02 balance equation (E) is established from the moving speed of 02 to 02 and the dissipation speed of 02 dissipating into the air as Go.

2J day 1 + 2JTt ÷ JMn 10J○ + 2.5JP + JF
llO・J8・JO= 0... Q groan Therefore,
If the molten iron component and the slag component before treatment are given, (9)
By simultaneously formulating equations .about.(c), the concentration %i'' and (%j)'' of each component at the reaction interface and the moving speed Jk can be determined.

Now, the reactant injected into the molten iron immediately turns into fine particles and slags after coming into contact with the molten iron. These slag particles (hereinafter referred to as reaction particles) start a reaction with molten iron, and in this reaction, the concentration %i'' of each component on the reaction surface and the (minor) movement speed Jk are also 1, as described in (9) above. It can be calculated using the formula ~ (c).Also, when used as a carrier gas in 02', immediately after this gas OwB is blown, it reacts with Fe and becomes FeO, so as Fe0 particles commensurate with the amount blown in. can be handled.

Therefore, if the component concentration %l at the reaction interface is determined, the weight change of each component within the reaction particle during the floating process can be determined by the following four equations.

aW1/at = Ap・kr'・ρB/100・(%
i'a・%ib) ...Kan AP = 4π(Dp/
2)”・Np ・・・・・・・・・・・・ (1)
However, AP; reaction interfacial area of reaction particles ωi]Dp
i Diameter of reaction particles kPl; Mass transfer coefficient on the molten iron side in transitory reaction 18〕 ρ; Equilibrium concentration of reaction particles at the reaction interface [
[H]Np f Supply rate of reaction particles (1
/s) Furthermore, in the same way as the transitory reaction, the permanent reaction is also based on the concentration %s of each component at the reaction interface between the floated reaction particles and the molten iron, and the amount and composition of the floated reaction particles in the slag on the molten iron. The weight change of each component is determined by the following Oe formula.

aWV'at = AIH-kB' ・ρa//10
0 H(%iIf -%1 ”)”Ptn($1)”
・A@However, the weight of i component in Wi i slag [1] At
; Reaction interface area between molten iron and slag on molten iron [CIIL2
[k81] Mass transfer coefficient between molten iron and slag in permanent reaction [crrL/s] Pin, weight velocity of floating particles [g/II]%1
1; Equilibrium concentration at the reaction interface between molten iron and slag on the molten iron [chi] (%); ; is the concentration of components in the floating particles [chi] On the other hand,
Since each component in the molten iron also changes as the permanent reaction and transitory reaction proceed simultaneously, the amount of change in each component per unit time can be determined by the following equation 62.

8Si at =Ap・k,%(%i'j−%i”)/
Vm+At, -! (Sit-Si"Nm...
(a) where V, +volume of molten iron [cIrL3] Therefore, the amount of reaction of each component can be found by integrating the zero-displacement equation over the processing time.

Next, a specific method for estimating the reaction amount of each component mentioned above will be explained based on FIG. 2 showing an example thereof. This figure 2 is an example using the time difference method, and in the figure 1
are the parameters necessary for estimating the reaction amount, that is, the type of reactant, the amount of injection, the depth of injection, the type of carrier gas, the amount of injection, and the actually measured components of molten iron, the measured temperature T1, the actually measured slag components before treatment, etc. This is an input section for input.

2 is the floating time of reaction particles in molten iron (tf), which will be described later.
, Calculating the transfer coefficient of each component in the transitory reaction and the transfer coefficient of each component in the one-permanent reaction. The calculation unit 4 calculates the component concentration q6i'' and calculates the first term on the right-hand side of equation 32.
The weight and composition of the slag on the molten iron are determined by the above zero formula, based on the determination part that determines whether the cumulative calculation time has exceeded the floating time of the reactive particles, and the composition and amount of the floating reactive particles. This is the calculation part that calculates.

6 uses the above equations (9) to (c) to calculate the concentration of each component at the reaction interface in the permanent reaction, calculates the second term on the right side of the above equation Q4, and in addition, calculates the concentration of each component at the reaction interface in the permanent reaction. This is the calculation part that calculates the reaction amount of each component, which is the left side of the equation.

7 -i, a part for determining whether the cumulative calculation time exceeds the calculation operation time, a part for proceeding with the steps of the 8tI'i calculation;
Reference numeral 9 is a part for proceeding with calculation steps when calculating the reaction amount of the floating reaction particles.

Then, from the parameters from the input section 1, the calculation section 2 calculates the floating time of the reaction particles, the transfer coefficient of each component, etc., which vary depending on the control requirements described later. Next, the amount of reaction between the reaction particles floating in the molten iron and the molten iron is calculated by repeating the calculation operations 3 → 4 → 9 while calculating the component concentration side at the reaction interface in calculation section 3, until the reaction particles finish floating. calculate. Next, the floating reaction particles are added to the slag on the molten iron, so the calculation unit 5 calculates the weight and composition of the slag on the molten iron from the actually measured slag components before treatment, the amount of reactant blown in, the type, etc.

Further, in the calculation section 6, the permanent reaction amount and the transitory reaction amount while the reaction particles float in the molten iron are calculated separately, and their sum is calculated.

The above calculation process corresponds to one cycle of calculations from when the reaction particles are blown into the molten iron until they float up. This cycle is repeated one after another until the cumulative calculation time (Tr) exceeds a preset calculation operation time, and when the calculation operation time exceeds the calculation operation time, the calculation ends. As a result, the estimated reaction amount of each component under the operating conditions can be estimated from the concentration of each component after a predetermined period of time has elapsed from the start of refining and the actually measured component input into the input section 1.

By the way, the target component temperature 0 and target temperature To of the molten iron
By actually measuring each component and temperature, it is possible to determine the required reaction amount for each component, and by comparing the estimated reaction amount and the required reaction amount, it is possible to determine the target amount under the operating conditions. The difference between the reaction amount and the actual reaction amount can be determined. If the difference occurs, the control factors that affect the reaction amount may be controlled so as to minimize the difference.

FIG. 1 is a block diagram for explaining the overall control mechanism of the present invention. In the figure, reference numeral 11 indicates an actual measurement value display section for the molten iron, and the actually measured values of each component and temperature T1 are input. Further, 12 is a target value display section, into which target component process 0 and temperature To are input. Reference numeral 13 denotes a calculation unit that calculates the required reaction amount ΔT6 and the allowable temperature drop amount ΔT6 from the target value and the actual measured value, and these are calculated by the following equations and (b), respectively.

△Work = Work 1 - IO・Song・Concave curve (to) △T=='l'1-'po ... Between songs (C) 14
Estimated reaction amount of each component △Work 3 and estimated temperature drop/lower leaf △T
3, and 16 is an input section for these two estimators. The calculation unit 14 calculates the estimated reaction amount Δ<i>3 by the above-described calculation operations, and also calculates the estimated temperature drop amount from the amount of heat dissipated within the processing time and the reaction heat accompanying the reaction of each component. 15 is a control requirement input section, and 17 is a control requirement selection section. Reference numeral 18 denotes a comparison section that compares the required reaction amount Δ<i>k with the estimated reaction amount Δ<i>3 . This comparison section compares whether the difference between the required reaction amount ΔF and the estimated reaction amount ΔF 3 is within a preset tolerance ΔX. Reference numeral 19 denotes a comparison unit that compares the allowable temperature drop amount ΔT with the estimated temperature drop amount Tat. Then, a comparison section 18 compares the .DELTA.work from the calculation section 13 and the Iae from the input section 16. If it is not satisfied that the difference between ΔF, ΔF3 and Q is within the allowable error range, the target reaction amount cannot be obtained, and a command to that effect is sent to the selection unit 1.
Enter 7. The selection unit 17 selects control requirements to be controlled based on the comparison result of the comparison unit 18, inputs them to the control requirement input unit 15, and calculates the estimated reaction amount and estimated temperature drop again in the calculation unit 14 based on the control requirements. Calculate the amount and compare the corrected Δwork 3 and Δwork. This calculation operation is repeated until the difference between Δwork and Δwork 3 falls within the allowable error range. When the comparison result by the comparing section 18 is within the above-mentioned allowable range, the comparing section 19 compares ΔT and ΔT3, and if the estimated temperature drop is larger than the allowable temperature drop, the same as in the case of the reaction amount is performed. The above operation is repeated until the conditions of the comparison section 19 are satisfied.

When the conditions of the comparators 18 and 19 are satisfied, an operation command is issued, and the refining operation is performed by controlling each control requirement based on the control requirement parameters at that time. still,
11 and Txk as appropriate during operation, and the measured values are
By inputting data into the actual measured value display section 11 and performing the above-mentioned operations, the refining status can be monitored and control requirements can be controlled according to the status, thereby achieving more efficient and highly accurate operation. is possible.0 Next, an example of a specific control procedure for minimizing the above-mentioned difference will be explained.

Among the various control requirements, changes in the blowing rate and type of reactant and the type of carrier gas directly affect the amount of reaction.

On the other hand, changes in the injection depth of the reactant, the injection amount of the carrier gas, and the number of lances mainly depend on the floating time of the reaction particles in the molten iron, the mass transfer coefficient between the molten iron and the reaction particles, and the relationship between the busy molten iron and floating slag. The effect can be estimated by controlling these factors, since they affect the mass transfer coefficient between them.

For example, by changing the blowing depth, the blowing amount of carrier gas, and the number of lances, the stirring force applied to the molten iron can be greatly varied. Therefore, it is possible to control the reaction amount using this stirring force as an index. That is, the stirring force ε applied to the molten iron is given by the following equation 09, where the carrier gas injection amount Q1, the molten iron temperature T1, the injection depth H1, the weight/weight W of the molten iron, and the temperature frost of the injection gas.

a = 6.18・Q-T/W・(An(1+HA, 4
8) +α・(1-Tz'I'n) ) ・-e; 4 However, α; Coefficient The floating time of the reaction particles in molten iron is expressed as the following formula (to) using the stirring force given by the above formula (g). be able to.

τ・1・Hno・6n1・・・・・・＜3QHowever, 1, old ; Regarding the constant mass transfer coefficient due to the state of the reaction vessel, the molten iron side between the molten iron and the reaction particles and the reaction particle side Mass transfer coefficient trace, 2 Mass transfer coefficient between molten iron and slag on molten iron side and slag side kB N J
k can be expressed as the following formulas 6η to 0Q using the stirring labor of formula (to) above.

kl ・= K2・εn2・・・・・・3 to 0ηkP・
・ε ・・・・・・(b) kB = 4. , n4, , , , , . 1. ,,,,,,
,,,,,, @kl = KS・, n5...
@υHere, CK2~5* and n2~n6 are all constants due to the shape of the reaction vessel.

The number of lances also affects the mass transfer coefficient, and the degree of influence is the mass transfer coefficient Kf3 when blowing with one lance.
It can be expressed by the following @η formula as the s2 standard.

kn=N, KS l...←η However, kn is the mass transfer coefficient when the number of lances is n. Ks1 is the mass transfer coefficient when the number of lances is 1. Each coefficient in the multi-member formula can be determined in advance based on the shape and size of the reaction vessel.

Table 1 shows an example of the coefficients determined for a 200 ton torpedo car.

Therefore, when changing the blowing depth, the blowing amount of carrier gas, and the number of lances, use formula (c) to calculate the stirring force af,
Then, using equations (to) to (6), the floating time of the reaction particles,
The mass transfer coefficient between the molten iron and the reaction particles and the mass transfer coefficient between the molten iron and the slag on the molten iron may be determined, and each of the above requirements may be appropriately controlled according to the obtained values.

Figure 3 is a chart showing the change over time of each component in molten iron during desiliconization treatment, comparing the values estimated based on the present invention at 1- with the values determined from the sampling results of molten iron based on the conventional method. It is. As is clear from FIG. 3, the estimated reaction amounts of each component determined based on the present invention follow the actual sampling results with extremely high accuracy.

The operating conditions in this example are as shown in Table 2, and the ratio of reactant iron sand to Ca0O is sand VCaO = 4:1.
And so.

By the way, Table 3 below shows that when selecting the control requirements,
This is a comparison of the degree of influence by different factors such as controllability, operability, and cost.

As shown in Table 3, if controllability of reaction rate, etc. is important, by appropriately selecting and setting the blowing depth, carrier gas flow rate, reactant blowing speed, reactant type, and number of lances in that order,
Effective operations can be carried out. Similarly, when emphasizing operability in terms of ease of operation, it is effective to control the blowing depth, carrier gas flow rate, reactant blowing speed, number of lances, and reactant type in that order.

In addition, if emphasis is placed on costs such as the basic units of reactants, carrier gas, etc. and lance manufacturing costs, the blowing depth, number of lances, gas flow rate, reactant type, and reactant blowing speed should be controlled in that order. is necessary.

Therefore, one or a combination of two or more of the most effective control requirements may be selected based on the comparison results by the comparison units 18 and 19 and various other conditions.

(Examples) Example 1 The present invention was carried out in a desiliconization operation for 200 tons of hot metal stored in a torpedo car. The measured values and target values of the hot metal components are shown in Table 4. Therefore, in this embodiment,
ΔSt was 0.5%, ΔT was 20° C., iron sand and CaO were used as a desiliconizing agent at a ratio of 4:1, and N2 gas was used as a carrier gas.

Table 4 Table 5 As initial conditions, control requirements are set as shown in Table 5, and the components and temperature after treatment are estimated from the estimated reaction amount based on the present invention, and the results of estimated value 1 in Table 4 are I got it. Although each component satisfies the target value, the estimated temperature after treatment is 1395℃
It was found that the target temperature was not reached. Therefore, with emphasis on controllability, if the blowing depth of the control requirements is set to 1400 steel, the estimated value will be 2, and the + Serise gas flow rate will be set to 60 mm.
0 Nn? /hr/piece, the estimated value is 3, and it was found that in both cases, not only each component value but also the temperature satisfied the target value. Therefore, the operation was carried out by controlling the blowing depth to 1400 mm, which is advantageous in terms of cost. As a result, the final components were as shown in Table 6, and the actual temperature after treatment was 140.
We were able to achieve the target temperature of 2℃.

Table 6 Example 2 Next, an example of simultaneous dephosphorization and desulfurization treatment of hot metal will be described.

In this example, as in Example 1, the present invention was carried out in the dephosphorization and desulfurization treatment of 200 tons of hot metal stored in a steel tank. The actual measured values and target values of the hot metal components are shown in Table 7.

As the reactants, iron sand and OaO were used in a ratio of 2:3, and as the cow seri gas, N2 gas and O2 gas were used in a ratio of 1:2.

When we searched for the optimal control requirements using a method similar to the desiliconization treatment shown in Example 1, we estimated that the estimated values shown in Table 7 could be changed if we operated under the conditions shown in Table 8. Since it was estimated that both temperature and temperature would satisfy the target values, operations were carried out under the conditions shown in Table 8. As a result, as shown in Table 7, the final measured values after treatment were able to achieve all target values for both components and temperature.

Table 7 Table 8 Example 3 Next, an example of desulfurization treatment of molten steel will be described.

In this example, the present invention was implemented in a desulfurization treatment operation for 180 tons of molten steel stored in a molten steel ladle. The actual measured values and target values of the molten steel components are shown in Table 9.

Table 9 OaO was used as the reactant, and Ar (alkoxy) gas was used as the reactant.

This was also carried out using the same procedure as in Example 1 and Example 2.
As a result of searching for the conditions for the optimal control requirements, it was estimated that the estimated values shown in Table 9 could be changed if the operation was performed under the conditions shown in Table 10, and it was estimated that the target values for both components and temperature would be satisfied. Therefore, operations were carried out under the conditions shown in Table 10.

As a result, as shown in Table 9, the final measured values after processing are:
We were able to achieve all target values for both ingredients and temperature.

(Effects of the Invention) By implementing the present invention as detailed above, efficient operation can be performed under predetermined conditions. As a result, it was possible to reduce the basic unit consumption of reactants, cow celery gas, and refractories for blowing lasis, which are necessary for smelting, thereby significantly reducing the costs required for smelting operations.

In addition, since it is possible to stably produce molten iron with the target content while maintaining the target temperature, operations throughout the entire refining process from hot metal pretreatment to molten steel processing can be performed efficiently and at low cost. Many excellent practical effects have been confirmed, including a reduction in the consumption rate of various raw materials and the ability to stabilize refining, thereby reducing the occurrence of slag and reblowing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining the basic control mechanism of the present invention, and FIG. FIG. 3 is a chart showing an example of the results of applying the present invention to an actual refining process. l...Actual value input section 2...Calculation section 3...Calculation section 4...Comparison section 5...Calculation section 6...Calculation section 7...Comparison section 8
...Calculation progress section 9...Calculation progress section 11...
Actual value display section 12...Target value display section 13...Calculation section 14...Calculation section 15...Control requirement input section 1
6... Estimated value input section 17... Selection section 18... Comparison section 19... Comparison section 1,... Target component value Technique 1... Processing agent actually measured component value ■3... Estimation Component value T,...Target temperature Tl...Treatment agent actual temperature ΔT...Allowable temperature drop amount △T3...Estimated temperature drop amount tf...Reactant particle floating time Tr...Calculation processing time
△Work...Target reaction amount △Work 3...Estimated reaction amount ■・
・・Tolerance 1ift (interval IN) for Figure 1, Figure 2, Figure 3

Claims (1)

[Claims] 1. In a molten iron refining method in which a reactant is injected together with a carrier gas into molten iron such as hot metal or molten steel in a container, a target amount of each component I_0, a target temperature T_0, and a target processing time of the molten iron are set. Determine the required reaction amount for each component from the actually measured amount of each component I_1 and the measured temperature T_1, and also calculate the type of reactant, the amount of injection, the depth of injection, the type of carrier gas, the amount of injection, and the amount of molten iron I_1, T
_1. Using the measured slag component before treatment as a parameter,
Chemical equilibrium concentration at the reaction interface between molten iron and slag, the amount of movement of each component based on the concentration difference between molten iron and slag, and O_2
The reaction amount of each component between molten iron and slag is estimated at the same time from the O_2 balance between the transfer rate to slag and molten iron and the atmospheric dissipation rate with respect to the supply rate, and then the estimated reaction amount and the necessary reaction amount are While controlling one or more of the following: the type of reactant injected, the amount of injection, the depth of injection, the type of carrier gas, the amount of injection, and the number of lances so that the difference is minimized. A smelting method for molten iron characterized by smelting. 2. Calculate the estimated amount of reaction for each component between molten iron and slag, the amount of reaction between slag floating on top of molten iron and molten iron, and the amount of reaction between reactive particles floating in molten iron and molten iron, respectively.
A method for refining molten iron according to claim 1, characterized in that estimation is made from the sum of the molten iron.