CN1019669B - Pig iron smelting reduction method and equipment - Google Patents

Abstract

A method for smelting reduction of iron ore comprises the steps of : preheating and prereducing iron ore ; charging said preheated and prereduced iron ore , carbonaceous material and flux into a smelting reduction furnace(10) ; blowing oxygen gas through a top blow oxygen lance(21) having decarburizing nozzles(25) and post-combustion nozzles(26) into said smelting reduction furnace (10), an end of said top blow oxygen lance(21) being arranged between an upper side level of a slag layer(12) and a lower side level ofsaid slag layer(12) ; blowing a stirring gas through at least one side tuyere(25) placed in side wall of said smelting furnace (10) and at least on bottom tuyer (26) placed in bottom wall of said reduction furnace (10) so that at least part of said stirring gas introduced through at least one said side tuyere hits a swollen portion of the molten metal by said stirring gas introduced through at least one said bottom tuyere(26); and controlling a flow rate of said oxygen gas and saidstirring gas blown in said smelting reduction furnace (10) so that an OD of infurnace gas of said smelting furnace (10) ranges 0.5 to 1.0. where said OD is represented bythe following formula : OD = ( H2O + CO2 )/( H2+ H2O + CO + CO2 ). And, further,an apparatus used in the above-mentioned method.

Description

The present invention relates to a method for smelting reduction of pig iron; in particular, in this method carbonaceous matter is used as both fuel and reducing agent, and iron ore is smelted and reduced in a top-blown oxygen furnace. The invention also relates to related devices.

The smelting reduction method has recently been fully developed to replace the blast furnace ironmaking method, which overcomes many of the latter's disadvantages; the blast furnace ironmaking method not only requires expensive construction costs, but also requires a large construction site.

In an earlier smelting reduction method, iron ore was pre-reduced by an exhaust gas, and then the pre-reduced iron ore was charged into a smelting reduction furnace together with carbonaceous material and flux. Then the oxidizing and stirring gas is blown into the smelting reduction furnace. Then, the carbonaceous material is melted by the molten pig iron loaded in advance, and at the same time, the carbon contained in the carbonaceous material is oxidized by oxygen. By the heat generated by this oxidation, the ore is smelted and reduced by the carbon contained in the carbonaceous matter. The CO gas produced in the molten metal is turned into CO ₂ gas due to the excess oxygen blown in. The sensible heat of this _CO2 is transferred to the slag and the iron particles in the slag covering the surface of the molten pig iron, and then to the molten pig iron.

In this way, iron ore is reduced to molten pig iron. In this process, iron ore is pre-reduced in order to lighten the load of the reduction process in the smelting reduction furnace; for example, As disclosed in a Japanese patent No.434 06/86, before the iron ore is loaded into the smelting reduction furnace, it is pre-reduced with a reduction degree of 60 to 75%. As a result, the exhaust gas from the smelting reduction furnace becomes a highly reducing gas with a low degree of oxidation, and a large amount of this exhaust gas is forced to be required.

If the iron ore is pre-reduced in a proportion of at least 30% before being charged into the smelting reduction furnace in order to reduce the load of the reduction process in the smelting reduction furnace, the degree of oxidation (hereinafter referred to as "OD" of the exhaust gas from the smelting reduction furnace ) is required to decrease; here OD is expressed by the formula "(H ₂ O+CO ₂ )/(H ₂ +H ₂ O+CO+CO ₂ )". As a result, the amount of exhaust gas must increase; for example, Japanese Patent No. 43406/86 has shown this point. The increase of this waste gas naturally improves the production cost. Therefore, in order to obtain a higher pre-reduction ratio of iron ore, a waste gas with low OD is required, and the residence time of iron ore in the pre-reduction furnace has to be longer than that in the smelting reduction furnace. Thus, the balance between the various cycles of loading pre-reduced iron ore and discharging the produced molten pig iron is difficult to control. The inevitable consequence of this situation is to strictly limit the control range in the smelting reduction furnace.

In addition, in order to increase the melting speed of iron ore and accelerate the reduction of iron ore, it is customary to adopt a method of releasing CO gas in a smelting reduction furnace and utilizing the heat generated thereby, in which the subsequent O ₂ The gas is fed through some tuyeres located on the roof of the smelting reduction furnace. However, in the conventional method, although the temperature of the exhaust gas can be increased when the ratio of the exhaust gas is increased, the sensible heat transferred to the molten pig iron is insufficient. The consequence of this situation is that high-temperature exhaust gas is forced to be discharged. The problem with this method is that such a high temperature gas attacks the refractory inner walls of the smelting reduction furnace.

Therefore, it has been generally believed so far that the OD of the exhaust gas cannot be increased to such a degree. In view of the above problems, the purpose of the present invention is to provide a smelting reduction method, thereby obtaining good heat transfer efficiency, protecting the refractory inner wall from the thermal attack caused by it, achieving high-efficiency preheating and pre-reduction, and ensuring reasonable work performance.

According to the present invention, a kind of smelting reduction method of pig iron is provided, and this method comprises the following steps:

Preheating and prereducing iron ore;

Load the preheated and pre-reduced iron ore, carbonaceous material and flux into a smelting reduction furnace;

Oxygen is blown into the smelting reduction furnace through a top-blown oxygen lance with a decarburization nozzle and a subsequent nozzle, and one end of the top-blown oxygen lance is placed between the upper plane and the lower plane of the slag layer;

A stirring gas is blown through at least one side tuyere on the side wall of the smelting reduction furnace and at least one bottom tuyere on the chassis of the reduction furnace, so that at least a part of the stirring gas sent through the at least one side tuyere is impacted by at least one bottom tuyere The bulging part of the molten pig iron caused by the stirring gas sent into the tuyere;

The stirring gas is at least one gas selected from the group consisting of Ar, _N2 , CO, _CO2 and process gas;

Adjust the flow of oxygen and stirring gas blown into the smelting reduction furnace so that the OD of the furnace gas generated by the smelting reduction furnace is in the range of 0.5 to 1.0 (excluding 1.0);

Furthermore, according to the present invention, there is provided a device conforming to the above method, comprising:

A preheating pre-reduction furnace for preheating and pre-reducing iron ore;

a smelting reduction furnace into which preheated and prereduced iron ore, carbonaceous material and flux are charged, and in which the iron ore is melted and reduced;

A top-blown oxygen lance having decarburization nozzles and subsequent nozzles and blowing oxygen into said smelting reduction furnace;

At least one side tuyere located on the side wall of the smelting reduction furnace and at least one bottom tuyere located on the chassis of the smelting reduction furnace, through which a stirring gas is blown in respectively, so that at least a part of the The stirring gas impinges on the bulge of the molten pig iron caused by the at least one bottom tuyeres.

This and other objects and advantages of the present invention will become apparent after the subsequent detailed description with reference to the accompanying drawings.

Fig. 1 is the schematic diagram showing the iron ore smelting reduction plant embodiment of the present invention;

Fig. 2 is a view showing the gas flow in a smelting reduction furnace constituting a part of the apparatus shown in Fig. 1;

Fig. 3 is a view showing the positional relationship between each side air port and each bottom inner port of the present invention;

Fig. 4 is the figure that shows heat transfer efficiency and oxygen lance height relation among the present invention;

Fig. 5 is a graph showing the relationship between the heat transfer efficiency and the side blowing gas flow rate in the present invention.

According to the research on the working mechanism of the smelting reduction furnace and the determination of improving the heat transfer efficiency and promoting the reduction of iron ore, the inventors have drawn some conclusions.

(1) According to the basic concepts in some prior art mentioned above, due to improving the Due to the technical limitations of the thermal efficiency method and the damage to the thinner furnace wall of the smelting reduction furnace due to the overheating of the post-combustion, the post-combustion ratio cannot be greatly increased. However, if oxygen is blown into the slag bed and at the same time the slag is vigorously stirred so that the afterburning takes place mainly within the slag bed, a high degree of afterburning can be achieved while maintaining a high heat transfer efficiency. Then, due to the high degree of after-combustion, the slag and the molten pig iron pellets contained in the slag are supplied with sufficient heat so that the iron ore reduction process by C appearing in the following formula can be efficiently carried out, where O refers to Carbon contained in molten metal in the form of either droplets or pools of metal.

(2) Among the prior art methods, there are instances where oxygen bottom blowing is carried out during the whole or a certain period of the reduction operation. This oxygen bottom blowing is detrimental to a high degree of afterburn. That is, when oxygen bottom blowing is carried out, a large amount of CO gas will be generated in the molten pig iron, and the molten pig iron will be strongly stirred. As a result, the splashed molten pig iron enters the afterburning zone, and C contained in the splashed molten pig iron reacts with oxygen so that the afterburning ratio is reduced. Therefore, regardless of the length of bottom blowing, oxygen bottom blowing must be avoided.

Based on these understandings and experience, the present invention has realized a kind of highly efficient reduction operation, and the condition of regulation is as follows:

(a) The combination of side blowing and bottom blowing of the stirring gas makes the molten pig iron automatically diffuse into the area where the iron ore exists in the slag layer, and promotes the reduction of the iron ore formed by C in the molten pig iron effect.

(b) The decarburization nozzle and afterburning nozzle are placed in a top-blown oxygen lance and pass through them Oxygen is sparged so that the predetermined or higher OD level is achieved. Oxygen through the afterburning nozzle is fed into the slag layer, forming a zone in the slag layer where afterburning takes place. The slag layer is vigorously stirred by the side-blown gas and the top-blown gas. Thus, the heat generated by the post-combustion can be transferred to the iron ore.

(c) At least one gas selected from the group consisting of Ar, N ₂ , CO, CO ₂ and process gas is used as a stirring gas, which is blown through the side walls and the chassis so that the degree of afterburn will not decrease . Oxygen is not used for this purpose.

In addition to the above, in the present invention, powdered carbon, fuel oil or steam is blown through the upper cover part or the upper part of the side wall of the smelting reduction furnace, the exhaust gas discharge pipe of the reduction furnace, or the gas modification tuyere of the preheating and prereduction furnace. This blowing will improve the quality of the gas generated in the smelting reduction furnace and reduce the OD of the generated gas in the furnace; and the modified gases will contribute to a higher degree of pre-reduction. The temperature of the upgraded exhaust gas is preferably controlled in the range of 300 to 1,300°C. If the temperature is lower than 300°C, no preheating effect can be expected, and in addition, there is concern about the trouble of tar during the gas reforming process. Conversely, if the temperature exceeds 1,300°C, insulation problems will occur in the equipment. Furthermore, lowering the temperature by means of gas modification is also beneficial in terms of the thermal insulation of the equipment.

Embodiments of iron ore smelting reduction equipment in the present invention will now be described in detail with reference to the accompanying drawings. Fig. 1 shows the block diagram of iron ore smelting reduction equipment in the present invention. In FIG. 1, two Ms mean that two Ms are connected to each other, and two Ns mean that two Ns are connected to each other. In the smelting reduction furnace 10, a molten metal pool 11 and a slag layer 12 are formed. The smelting reduction furnace has a top-blown oxygen lance 21 vertically inserted into the slag layer. The end of the top-blown oxygen lance is equipped with a decarburization nozzle 22 and a post-combustion nozzle 23, and oxygen is blasted into the furnace 10. Side tuyeres 25 and bottom tuyeres 26 are respectively housed on the side wall and chassis of the furnace 10, through which stirring gas is blown. This gas is at least one gas selected from the group consisting of Af, N ₂ , CO, CO ₂ and process gas. The process gas is a gas generated in the smelting reduction equipment in the present invention.

A first chute 13 and a second chute 14 are respectively installed on the left and right sides of the top of the furnace 10 . Through the first chute 13 and the second chute 14, the carbonaceous material and flux supplied by the charging machine (for the sake of brevity, not shown) and the preheating and pre-reduction furnace 30 of the fluidized bed type are preheated. The reduced iron ore is loaded into the smelting reduction furnace separately by gravity. The furnace is provided with an exhaust pipe 15 for exhaust gas discharged from the furnace 10 . It should be noted that the fluidized bed type preheating and pre-reduction furnace can be replaced by a shaft furnace and a rotary kiln type furnace; the shaft furnace has a higher thermal efficiency, and the rotary kiln type furnace equipment cost is low and easy to operate; this does not affect the characteristics of the present invention There will be no hindrance.

One or more gas modifying tuyeres 9 are installed on the upper part of the exhaust pipe, through which powdery carbon material, fuel oil or steam is blown in as a gas modifying agent; the quality of the exhaust gas is improved to make it a Gases with low OD values. In addition, it is also equipped with: a hot cyclone dust collector 31, into which the waste gas is sent from the smelting reduction furnace 10, and the dust is removed without losing the high heat of the waste gas; a preheating and pre-reduction furnace 30, into which the waste gas is preheated Iron ore; the separator 35 receives the waste gas from the preheating and pre-reduction furnace, and removes the iron ore particles contained in the waste gas. There is also a pressure unit 27 for mixing the iron ore particles separated from the iron ore in the separator 35 with a carrier gas to form a mixture and pressurizing the mixture. This mixture is blown into the furnace 10 through side tuyeres 25 and bottom tuyeres 26 . It should be noted that a portion of the iron ore fines may also be returned to the preheating and prereducing furnace 30 to be preheated and prereduced as iron ore, although not shown in FIG. 1 . Furthermore, for the sake of utilizing heat, it is very effective to install a preheater to preheat iron ore without the separator 35. As the carrier gas, one gas selected from the group consisting of Ar, _N2 , CO, _Co2 and process gas can be used.

Next, an iron ore smelting reduction method used in the smelting reduction apparatus explained above will be described. The iron ore as raw material is loaded into the preheating and prereduction furnace 30 from the charging machine (not shown). After preheating and prereduction in the furnace 30, the iron ore is loaded by gravity through the second chute 14. into the smelting reduction furnace 10. Various carbonaceous materials and flux are also loaded into the furnace 10 by gravity through the first chute 13 . A molten metal pool 11 and a slag layer 12 are formed in the smelting reduction furnace. Furnace gas generated in the slag layer 12 of the smelting reduction furnace 10 increases the OD value due to the reaction in the furnace which will be described in detail later. This gas in the furnace goes up along the exhaust pipe 15, ready to enter the pre-reduction furnace 30, and the gas in the furnace as exhaust gas will meet with a gas modifier, and the latter will pass through the gas placed on the upper part of the exhaust pipe 15. The reforming tuyere 9 blows into the exhaust pipe 15 . The reforming operation of this exhaust gas will also be explained in detail later.

The gas in the furnace whose OD value (expressed by the formula given below) is increased due to the reaction in the furnace can reduce the OD value by means of a gas modifier:

OD=(H ₂ O+CO ₂ )/(H ₂ +H ₂ O+CO+CO ₂ )...(1)

The gas in the furnace whose quality has been improved through such modification is sent to the preheating pre-reduction furnace 30 as waste gas. The iron ore is preheated and pre-reduced in the preheating and pre-reduction furnace, and then loaded into the smelting reduction furnace through the second chute 14 . At the same time, the exhaust gas enters the separator 35. After the iron ore particles are separated from the exhaust gas in the separator, the exhaust gas travels along two routes. Either one goes forward. One of the two routes is that the exhaust gas is discharged through a general exhauster; the other is that the exhaust gas is used as a process gas and is blown into the furnace 10 through the side tuyeres 25 and the bottom tuyeres 26 to become a stirring gas or a carrier gas . In addition, this exhaust gas can be sent into the exhaust pipe 15, mixed with the furnace gas discharged from the smelting reduction furnace, and used to control the temperature of the gas fed into the preheating and prereduction furnace 30.

Now, referring specifically to the accompanying drawings of Figs. 2 to 5, the relationship between the gas blown into the smelting reduction furnace 10 and the reaction in the furnace will be discussed in detail. FIG. 2 illustrates the effect of gas blown through side tuyeres 25 and bottom tuyeres 26 as shown in FIG. 1 . Arrows 28 and 29 below the oxygen lance 21 in FIG. 2 each indicate the direction of oxygen injected through the decarburization nozzle 22 and the afterburner nozzle 23, respectively. DC O ₂ represents the oxygen blown through the decarburization nozzle, and pCO ₂ represents the oxygen blown through the afterburning nozzle. Throughout the reduction operation, the gas blowing operation from the beginning to the end is carried out through the oxygen lance 21, the side tuyeres 25 and the bottom tuyeres 26. The gas blowing through the side tuyeres and the bottom tuyeres cooperate to diffuse the molten pig iron into the slag layer, with the result that the gas blowing strongly increases the reduction rate.

As mentioned at the beginning of the detailed description, based on the conclusion that the reduction of iron ore present in the slag layer 12 is mainly carried out by utilizing molten pig iron containing C as a reducing agent, the present invention attempts to make the iron The ore floats in the lower part of the slag layer and allows molten pig iron to diffuse automatically into this area to increase the rate of reduction. For this purpose, a stirring gas is blown into through the bottom tuyeres 26 to form deep molten pig iron bulges on the surface of the molten pig iron (as shown in A in Figure 2 ), and at the same time, a stirring gas is blown into through the side tuyeres 25 to make at least a part of it from the side The blown stirring gas hits the swollen portion A. The molten pig iron at the bulge A is splashed into the slag layer by this side-blown gas. The apparent specific gravity of a slag layer typically ranges from 0.1 to 0.5 g/cm ³ , while that of iron ore approximately ranges from 2 to 5. Thus, the iron ore 16 contained in the slag layer is concentrated in the lower portion floating on the slag layer 12 . When the swollen portion A of the molten pig iron is splashed by means of the side-blown stirring gas, the splashed molten pig iron 17 diffuses into the region of the lower portion of the slag layer 12 . The C contained in the splashed molten pig iron reduces the iron ore. A high reduction rate is thus achieved. In order to obtain this effect, it is preferable that the side-blown gas can impinge on the bulge A of the molten pig iron so that the bottom-blown gas and the side-blown gas cross each other at right angles as much as possible. In the horizontal direction, the placement of the side air outlets 25 and the bottom air outlets 26 should satisfy the positional relationship shown in Fig. 3 (a) and (b).

Figure 3(a) shows the positional relationship between the two in the case of using one side air outlet 25 and one bottom air outlet 26, and Figure 3(b) shows their position relationship in the case of using three side air outlets 25 and three bottom air outlets 26. Positional relationship. Arrows in FIG. 3 indicate the direction of the gas blown through the side air outlet 25 . Certainly, the quantity and positions of the side air outlets 25 and the bottom air outlets 26 are not always exactly as shown in FIG. 3 . The number of tuyeres can be determined according to the capacity and output of the actual smelting reduction furnace. In addition, a large amount of gas needs to be blown through the side air outlets 25 and the bottom air outlets 26 . The amount of gas blowing can be determined according to the amount of molten pig iron and the depth of the molten pig iron. In addition to the diffusion effect, the side-blown gas also stirs the upper part of the slag layer, where an afterburning zone is formed. This will also be elaborated on later.

The gas blown through the side tuyeres 25 and the bottom tuyeres 26 is at least one gas selected from the group consisting of Ar, N ₂ , CO, CO ₂ and process gas. However, _O2 gas is never used. The reasons are as follows: First, if the _O gas is blown sideways, a fundamental problem is involved that the reduction of C contained in the molten pig iron that has splashed into the lower part of the slag layer 12 will be weakened. Secondly, if _O2 gas is used as the bottom blowing gas, too much CO gas will be generated to subject the molten pig iron to excessively strong stirring. As a result, the splashed molten pig iron enters the upper region of the slag layer and reaches the afterburning zone (shown as B in Fig. 2), where combustion by _pCO2 takes place. Therefore, the afterburning is weakened due to the reaction of the C contained in the molten pig iron with the _O2 used for the afterburning. Also, the use of _O2 gas for bottom blowing will raise the temperature of the refractory material constituting _the bottom tuyeres 26 so high that a cooling gas such as _C3H3 must be added. This addition also increases the amount of bottom blowing gas and unduly accelerates the generation of splashing of the molten pig iron.

In the present invention, the afterburning zone is mainly formed in the slag layer, that is, in zone B, and a high degree of afterburning is realized. In this way, by adopting the method of forming an afterburning zone and blowing gas from the side of the slag layer with strong agitation, the goal of achieving a high degree of afterburning and still obtaining high-efficiency heat transfer can be achieved. Therefore, post-combustion oxygen mainly needs to be blown into the slag layer existing in the after-combustion area of zone B.

It is particularly necessary that the height of the top-blown oxygen lance be specified so that it has an appropriate level relative to the molten pig iron plane and the slag layer plane. In other words, if the nozzle of the oxygen lance 21 is excessively higher than the upper surface of the slag layer, the afterburning zone cannot be formed in the slag layer, and the heat transfer efficiency will decrease; on the contrary, if the nozzle is too low, it cannot form Proper afterburn zone. The lowest plane of the oxygen lance nozzle is equal to the lower side of the slag layer.

Fig. 4 shows that according to the relationship between the height of the oxygen lance top and the upper surface of the slag layer and the heat transfer efficiency according to the present invention, this relationship makes us realize that if the oxygen lance top is too high from the slag layer surface, satisfactory results cannot be obtained. heat transfer efficiency. Figure 5 shows that the amount of side blown gas is the same as the heat transfer efficiency Relationship. It can be seen from FIG. 5 that a satisfactory heat transfer efficiency can be obtained by blowing a large amount of side blown gas through the tuyeres 25 and vigorously stirring the slag layer. The results shown in Figures 4 and 5 were obtained from an operation using a smelting reduction furnace with a capacity of 5 tons producing molten pig iron at a rate of 28 tons/hour.

According to the present invention, since the thermal efficiency is high, a high reduction rate can be obtained by increasing the OD as described above. In addition, since the OD is increased, the amount of carbonaceous material added can be reduced. As a result, the unit consumption of carbonaceous substances can be saved, and at the same time, the p content of molten pig iron can be reduced, because most of the p in molten pig iron is brought in by carbonaceous substances. Furthermore, after the OD is increased, evaporative desulfurization will be promoted, so the S content of molten pig iron can be reduced. From these points of view, OD is best specified from 0.5 to 1.0 (excluding 1.0). If the OD is 0.7 to 1.0 (excluding 1.0), the reduction reaction in the smelting reduction furnace is promoted, so that the pre-reduction furnace becomes remarkably unnecessary.

As mentioned above, the gas with increased OD, i.e. low calorific value gas, can be modified by blowing powdery carbonaceous material; The gas reforming tuyere 9 located on the upper part of the exhaust pipe 15 is blown in together with the carrier gas; the OD of the reformed gas is less than 0.5. This upgraded gas is fed to a preheating and prereduction furnace where the iron ore is efficiently reduced. The carrier gas is at least one gas selected from the group consisting of _N2 , Ar, CO, _CO2 and process gas. As mentioned above, powdery carbonaceous material is a gas modifier, usually blown together with the carrier gas. However, depending on the particle size of the carbonaceous matter, it can be loaded into the gas reforming tuyere 9 by gravity. This also applies to the charging operation performed through the upper part of the smelting reduction furnace. As the gas modifying agent, it is recommended to use fuel oil or steam. At this time, factors such as cost, structure of the gas modifying tuyere, and exhaust gas should be considered.

In this embodiment, as mentioned above, the gas reforming tuyere 9 is placed on the upper part of the smelting reduction furnace. This arrangement makes it possible to freely select many blowing inlets in the vertical direction along the pipe wall of the exhaust pipe 15, so that the amount of blowing air is easy to control. In addition, when these tuyeres are placed on the upper cover and side wall of the smelting reduction furnace, these parts of the smelting reduction furnace, exhaust pipes and other related accessories can be protected from overheating, because the blown gas quality modifier will reduce The temperature of the exhaust gas. When the preheating and pre-reduction furnace is a fluidized bed type, relying on blowing the gas modifying agent into an air chamber, the gas modifying agent and the exhaust gas from the smelting reduction furnace are well mixed in the air chamber, and the modification of the exhaust gas will Proceed efficiently.

Finally, the specific numerical values obtained from the running results of each example of the present invention are listed in Table 1. These examples were taken under the same conditions as those of FIGS. 4 and 5 . The table shows the comparison between the case of gas reforming and the case of not performing gas reforming. Using the composition values of various exhaust gases in Table 1, each OD value was calculated according to the formula (1) given earlier. The OD value of the modified gas was 0.24, while the OD value of the unmodified gas was 0.51. Obviously the modified gas OD value is much lower than the unmodified gas OD value. In addition, the temperature of the modified gas is lower than that of the unmodified gas.

While the invention has been shown and described in detail with reference to preferred embodiments thereof, those skilled in the art will understand that the foregoing and other changes in form and detail may be made without departing from the spirit of the invention. and range.

Table 1

unmodified gas modified gas

Coal 328kg/min 225kg/min

(in molten metal pool) (in molten metal pool)

78kg/min

(for modification)

Iron ore 724 kg/min 720 kg/min

(in molten metal pool) (in molten metal pool)

CaCO ₃ 72 kg/min 74 kg/min

(in molten metal pool) (in molten metal pool)

O ₂ 232 standard ^m3 /min 165 standard ^m3 /min

exhaust gas

CO 44% 68%

CO ₂ 34% 14%

H ₂ 5% 8%

H ₂ O 17% 17%

Temperature 1,740°C 1,650°C

Claims (14)

1. A method for smelting reduction pig iron in a smelting reduction furnace, comprising the steps of: preheating and prereducing iron ore in at least one preheating and prereduction furnace by contacting the iron ore with furnace gases emitted from said smelting reduction furnace; Preheated and pre-reduced iron ore, carbonaceous material and flux are charged into a smelting reduction furnace, the bottom of which contains molten pig iron on which is a layer of slag; The decarburization oxygen and post-combustion oxygen are blasted into the top-blown oxygen lance to reduce the preheated and pre-reduced iron ore into molten pig iron and melt the flux into slag. Carbon and oxygen, after-burning oxygen is blasted through the after-burning nozzle; Stirring gas is blown through at least one side tuyere on the side wall of the smelting reduction furnace and at least one bottom tuyere on the chassis of the smelting reduction furnace; it is characterized by: One end of the top-blowing oxygen lance is arranged between the upper plane and the lower plane of the slag layer; The stirring gas is blown upward through the molten pig iron through the at least one bottom tuyere and causes the upper surface of a portion of the molten pig iron to bulge upward, and at least a portion of the stirring gas impinges on the molten pig iron through the at least one side tuyere. an upwardly bulging portion of the pig iron to agitate the molten pig iron and slag layer such that droplets of molten pig iron migrate into the slag layer; said stirring gas is at least one gas selected from the group consisting of Ar, _N2 , CO, _CO2 and process gas, and Control the flow of afterburning oxygen and stirring gas, so that the OD range of the gas in the smelting reduction furnace is 0.5 to 1.0 (excluding 1.0), wherein OD is determined by the following formula: (H ₂ O+CO ₂ )/(H ₂ +H ₂ O+CO+CO ₂ ) 2. The method of claim 1, wherein said OD is 0.7 to 1.0 (excluding 1.0). 3. The method of claim 1, further comprising the step of removing dust from the gas in the furnace and discharging it to the smelting reduction furnace without losing the heat of the gas in the furnace In addition, the furnace gas is then brought into contact with iron ore in a preheating and prereducing furnace. 4. The method of claim 1, further comprising the step of preheating the iron ore by contacting the gas discharged from the preheating and prereduction furnace, and the preheated iron ore is sent to into the preheating and pre-reduction furnace. 5. The method according to claim 1, characterized in that it further includes the step of reforming the gas in the furnace into a high-quality gas with an OD of less than 0.5 and preheating and pre-reducing the gas by means of this modified gas Iron ore in preheating and prereduction furnaces. 6. The method according to claim 5, wherein the step of reforming the gas in the furnace comprises reforming by at least one gas selected from the group consisting of carbonaceous matter, steam and fuel oil contact with an agent to modify the gas. 7. The method according to claim 5, characterized in that, the step of reforming the gas in the furnace comprises: blowing a reforming agent through a gas reforming tuyere located at a height above the slag layer in the smelting reduction furnace . 8. The method according to claim 5, characterized in that the step of upgrading the furnace gas comprises: passing the gas located in the exhaust pipe from the smelting reduction furnace to the preheating and pre-reduction furnace The reforming tuyere blows a reforming agent. 9. The method according to claim 5, characterized in that the step of reforming the gas in the furnace comprises blowing a reforming agent through a gas reforming tuyere provided in the preheating and pre-reduction furnace. 10. A smelting reduction equipment for pig iron comprising: A preheating and prereduction furnace for preheating and prereducing iron ore; a smelting reduction furnace into which said preheated and prereduced iron ore, carbonaceous material and flux are charged and in which said preheated and prereduced iron ore is melted and reduced; A top-blown oxygen lance that has a decarburization nozzle and a subsequent nozzle, and blows oxygen into a smelting reduction furnace containing molten metal at one end; its characteristics are: At least one side tuyere located on the side wall of the smelting reduction furnace and at least one bottom tuyere located at the bottom of the smelting reduction furnace, through which the stirring gas is respectively blown to impact the molten metal contained in the smelting reduction furnace so that the upper surface of a part of the molten metal Swelling upwards, at least a portion of the stirring gas, the at least one side tuyere impinges on the upward swollen portion of the molten metal to agitate the molten metal. 11. The apparatus of claim 10, further comprising at least one gas modifying tuyere through which a gas modifying agent is blown into the furnace gas exiting said smelting reduction furnace. 12. The equipment according to claim 11, characterized in that the reforming tuyeres are arranged at a position higher than the slag layer in the smelting reduction furnace. 13. The equipment according to claim 11, characterized in that the reforming tuyeres are arranged in an exhaust pipe which transports the gas in the furnace from the smelting reduction furnace to the preheating and prereducing furnace. 14. The equipment according to claim 11, characterized in that said preheating and prereduction furnace is a fluidized bed furnace, and said reforming tuyere is set in the air chamber of the fluidized bed type preheating and reduction furnace .

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