KR20010004491A - The formation method of Ti-Bear on weak point of hearth carbon brick by multiple injection of TiO2 powder at blast furnace tuyere - Google Patents

Abstract

PURPOSE: A method for forming a viscous and dense layer of hearth by multi-stage injecting titanium dioxide powder ore into a blast furnace tuyere is provided to contribute to the cost reduction of molten pig iron and increase bricks of hearth lateral wall so that life cycle of a blast furnace can be extended by forming a stable titanium compound layer on the surface of hearth carbon bricks which are regionally damaged. CONSTITUTION: A simple or temporary adherent layer(711) is formed not only by tapping pig iron through a tapping hole which is located at opposite to a hearth eroded portion but also by injecting TiO2 through a tuyere(71) located at straight above the hearth eroded portion. The TiO2 is injected 3 to 4 times through a tuyere(72) which is separated an angle of 20 degrees from the eroded portion and simultaneously pig iron is tapped through the tapping hole which is located at opposite to the hearth eroded portion. The molten materials inside a blast furnace are bumped against the temporary adherent layer(711) forming vortex flow as well as being accumulated inside the hearth eroded portion so that the temporary adherent layer can be grown.

Description

The formation method of TiOBear on weak point of hearth carbon brick by multiple injection of TiO2 powder at blast furnace tuyere}

The invention therefore titanium oxide to the tuyere (TiO ₂₎ change, in particular blast furnaces used in the blow-by TiO ₂ spectroscopy in multiple stages and output pioneering way through the tuyere relates to nojeo viscous layer forming method according to the spectral multi-stage injection in conjunction enemy The present invention relates to a method for forming a bottom viscous layer by multi-step injection of TiO ₂ spectroscopy into a blast furnace flue that can stably form a titanium compound at a local erosion site with a bottom carbon lead to prevent breakage with the bottom edge.

FIG. 1 is a diagram showing TiO ₂ reduction behavior and TiC formation behavior in a furnace, and FIG. 2 is a diagram showing the TiO ₂ reduction equilibrium arrival time in a furnace, and blast furnace operation descends to the furnace bottom by forming molten iron and slag from iron ore. do. The melt accumulated in the lower part of the furnace is discharged continuously through the outlet. Large blast furnaces usually have four outlets, of which alternately discharge the melt in the furnace in alternating two diagonal outlets. On the other hand, reference numeral 21: the initial concentration of the injected TiO ₂ , 22: TiO ₂ concentration with the reaction time, 23: equilibrium time without a change in concentration.

Inside the blast furnace there is a soft fusion zone, and underneath is a section consisting of pure coke only (deadman coke), where the melt is transferred to the mutual exit through the core coke and discharged out of the furnace.

If the liquidity of the core coke is poor, the melt is transferred to the opposite exit or adjacent exit through the area where coke does not exist or a relatively large space, and in this process, descends to the bottom of the bottom through the coke in the middle of the furnace. As a result, wind pressure rises and vortex phenomena underneath the exit can cause local erosion of the bottom edge.

Conventionally, as a means for suppressing local erosion of the furnace lead and 111, a method of mixing ore containing TiO ₂ in the top charge or using a specific blower to inject a spectrophotometer containing TiO has been used. .

In the former method, it is impossible to selectively load in the local erosion site 112, and a large amount of TiO ₂ light is unavoidable. The latter method has the advantage of being able to be put in the desired position. However, the operator is allowed to use the same as the operation factors, and by limiting the interval between the starting port in use and the blowing hole to be used (30 to 40 degrees apart from the local erosion site 112). That is, since only the basic concept depends on the blowing direction, the titanium compound layer in the furnace cannot be stably formed, and after a certain time, the titanium compound layer disappears and has to be re-injected.

In addition, there is a problem in that the blowing effect is not sufficient because the TiO ₂ spectroscopy blown without considering the reduction capacity in the combustion zone is not reduced to Ti, and is discharged out of the furnace together with the slag as TiO ₂ . In addition, the TiO ₂ is reacted with coke having a lowering of TiO ₂ to form TiC in the pores in the coke and grow, thereby promoting the differentiation of the coke and ultimately deteriorating the fluidity of the bottom part.

Reference numeral 121: TiO ₂ spectroscopic injection, 122: reaction in the combustion zone, 123: TiC formed in the vicinity of the combustion zone, 124: TiC formed in the reaction with the furnace coke, 125: TiC formed in the furnace edge and the surface, 126: Ti, 131: cooling ability in the thin portion of the lead is reduced to molten iron, 132: cooling ability in the thick portion of the lead.

The present invention is to solve the above problems, by adjusting the blowing direction, blowing amount, operating conditions of the TiO ₂ spectroscopy associated with the furnace run-off situation, so that the injected Ti component is not discharged to the outside of the furnace to stay in the vulnerable site At the same time the furnace because selective improve the external cooling power on, nojeo by TiO ₂ spectral multistage blown into the blast furnace tuyere to form a stable Ti compound layer on the surface with the damaged nojeo carbon opened locally extends the life with no low smoke The purpose is to provide a method for forming a viscous layer.

The above-mentioned object is the first step of forming a simple adhesion layer by drawing out the TiO ₂ through the air outlet located on the opposite side of the erosion erosion unit and simultaneously blowing the TiO ₂ through the air duct located in the upper portion of the erosion erosion unit. Including the second step of blowing the TiO ₂ through the spaced apart three to four times and at the same time through the outlet located in the opposite direction of the erosion portion, the melt inside the impingement layer to form a vortex At the same time, the temporary adhesion layer is grown while stagnating in the erosion part, and is achieved by a method of forming a bottom viscous layer by TiO ₂ spectroscopic multi-stage blowing into a blast furnace vent.

1 is a diagram showing TiO ₂ reduction behavior and TiC formation behavior in a furnace.

2 shows the TiO ₂ reduction equilibrium arrival time in the furnace.

3 is a diagram showing Ti activity according to oxygen partial pressure.

4 is a diagram showing Ti activity according to the Ti content in the molten iron.

5 is a view showing the TiC formation amount according to the Ti content in the molten iron.

Fig. 6 is a diagram showing a bottom part and a local erosion phenomenon.

FIG. 7 is a diagram illustrating a low smoke and a protective state by multi-step blowing of TiO ₂ spectroscopy. FIG.

FIG. 8 is a diagram showing a low smoke and a protective effect by multi-step blowing of TiO ₂ spectroscopy. FIG.

<Explanation of symbols for main parts of drawing>

21: Initial concentration of injected TiO ₂ 22: TiO ₂ concentration over time

23: Equilibrium time without change of concentration 31: Ti activity according to oxygen partial pressure

41: Ti content (converts general content into mole fraction)

51: TiC formation correlation graph according to Ti content in molten iron

61: Noh Yeon-wa (111) 62: The exit gate where local erosion of Yeon-wa proceeded

63: Yeonwa's local erosion exit 64: Core core

71: 1st blow 72: 2nd blow

111: union union and 112: yeonwa local erosion site (112)

121: TiO ₂ spectroscopic blowing 122: reaction in the combustion zone

123: TiC formed near the combustion zone

124: TiC formed in reaction with furnace coke

125: TiC formed on the surface of the bottom edge 111

126: Ti 131 reduced to the molten iron: cooling ability of the thin portion of the smoke

132: cooling capacity of the thick portion of the pontoon 711: adhesion layer formed by primary blowing

712: local erosion exit port 713: exit port where the melt is discharged during the first blow

721: melt flow in furnace after secondary blowing 722: stagnation of melt due to barrier effect near exit port

723: outlet for the melt to be discharged during the second blow

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In general, TiO ₂ spectroscopy blown through the tuyere is partially reduced to Ti in the combustion zone, unreduced TiO ₂ is incorporated into the slag and Ti drops to the bottom with molten iron. The amount directly reduced to Ti in the combustion zone is not relatively large, and TiO ₂ is gradually reduced to Ti and mixed into the molten iron by the interfacial reaction between slag and molten iron. It takes about 10 hours to fully reduce the Ti to the saturated state in the molten iron, which was confirmed by the experimental results of FIG.

Therefore, the blown TiO ₂ should be given the opportunity to stay in the furnace for at least 10 hours, which is more important because only Ti that is reduced into the molten iron can react with the carbon in the bottom wall edge to form TiC at the erosion site. Is the point.

In detail, there are four kinds of TiC formed in the furnace, firstly, TiC formed by reacting with carbon or CO gas generated in a combustion zone, and secondly, TiC2 formed by reacting with TiO ₂ and coke in slag. TiC formed by reacting with Ti in the molten iron and carbon or coke in molten iron, and Fourth, TiC formed by reacting carbon in the Ti bottom wall of the Ti molten iron in the molten iron.

Firstly, secondly, TiC deteriorates the fluidity of the melt that falls as solid particles, so that it does not fall to the bottom but stays in the lower part of the combustion zone. It forms and grows in the coke to act to differentiate. This adversely affects the liquidity of the core coke, which plays an important role in melt discharge from the furnace. The third TiC is formed in the molten iron, so it is hardly attached to the surface of the smoke and is mostly discharged outside the furnace.

Therefore, in order to maximize the blowing effect of TiO ₂ spectroscopy, the injected TiO ₂ is reduced to Ti as much as possible and at the same time, the reaction between TiO ₂ and coke is suppressed so that the injected TiO ₂ is sufficiently reduced to Ti to reach the nodal local erosion site. shall.

Sufficient reduction time is required for the maximum completion of Ti as can be seen in FIG. In addition, as can be seen in Figure 3, the oxygen partial pressure in the furnace should be small, thereby increasing the Ti activity. As can be seen in FIG. 4, when Ti activity is increased, the amount of Ti reduced into molten iron is increased, which means that the amount of TiC formation is increased by reacting with carbon lead as shown in FIG. 5. The relations of FIGS. 2 to 5 were determined through experiments (Master's Thesis for Pohang University: TiC formation behavior in blast furnace furnace), and confirmed through blown operation in actual blast furnace operation.

In order to satisfy the above TiC formation conditions, a two-stage blowing method was selected in the actual blowing. First is the first stage blow. When the melt from the exit hole in the opposite direction from the local wound part with the bottom edge is discharged, the TiO ₂ light is injected into the upper part of the damaged part to form a primary attachment, which prevents the melt from passing through the local damaged part at high speed. It also reduces the wear and tear and establishes the basic conditions for the melt to stay.

Second is the second phase. Normal departure is made for 150 ~ 220 minutes at one exit, so when the exit of the exit that was used in the first stage is finished, the exit is performed at the immediate exit, and the second stage is blown.

The second stage is blown three to four times at a blowing rate of 20 kg / min with a 20 ° interval from the local erosion site while maintaining an injection volume of 2.5 tons.

Operating condition at this time is with the front stop oxygen input which is input along with the pulverized coal lowering the furnace the oxygen partial pressure, raising the combustion temperature in the combustion against stop adjacent tuyeres coal injection in order to have a sufficient dissolving ability to injected TiO ₂ as soon as It should be melted and mixed into the molten iron and slag in the furnace and lowered to the bottom. TiO ₂ blown under the above conditions greatly increases the amount reduced to molten iron due to increased Ti activity, and also prevents deterioration in the fluidity of the melt by inhibiting TiC formed by reacting with the coke, thereby causing the loss of airflow due to the melt. It is possible to prevent the melted copper ball from melting due to the fact that the melt having poor fluidity cannot be lowered to the bottom and accumulates directly under the air hole.

Third, melt flow control in the furnace during the second stage blow. During the two-stage TiO ₂ continuous blow, the outlets directly above the local erosion site are discontinued and the two outlets on the opposite side are used alternately. Through this, the blown TiO ₂ is not immediately discharged out of the furnace, is sufficiently reduced to Ti while staying near the erosion site, and the reduced Ti reacts with the carbon in the side margin and forms TiC.

Fourth, TiC has grown stably after the second phase. When blowing is in progress and after the end, at least 10 hours have elapsed, the external cooling ability of the local erosion part is greatly improved, and the effect of rapid growth of TiC is achieved. I can make it.

Figure 1 shows the TiO ₂ reduction behavior and TiC formation process in the furnace, TiO ₂ (121) blown through the tuyere is dissolved by the reaction heat of the combustion zone 122, oxygen in the air, combustion zone 122 In reaction with the fine coke in the water, a portion is directly reduced to a solid (Ti) and descends to the bottom of the furnace together with the molten iron, and some is incorporated into the slag as the liquidated TiO ₂ . In addition, some react with coke falling from the top into the furnace to form a solid (TiC: 123).

If the slag incorporated into the slag does not have enough time to react with the dissolved carbon in the molten iron, it is mostly discharged out of the furnace or reacts with the surrounding coke to form and grow solids (TiC: 124) inside the coke, thereby adversely affecting the coke. Although it is reduced to Ti (126) in the molten iron by the interfacial reaction between the slag and molten iron can react with the carbon in the furnace side wall edge 111 to form TiC (112) on the edge and the surface.

The cooling capacity of the furnace is much stronger in the thin section 131 of the wedge, and the cooling capacity 132 in the thick section of the wedge is relatively weak. The growth of TiC grows faster with higher cooling capacity. Therefore, the TiC 125 formed on the surface of the local erosion part grows sufficiently stable if the external cooling ability is excellent and only time for Ti and the duct reacts is given.

Figure 2 shows the result of the equilibrium time measurement to reach the saturation state is reduced to Ti in the melt after dissolved with the TiO ₂ blown.

Initially, about 11% (21) of TiO ₂ was added to the slag and reacted with molten iron containing no Ti. As the reaction time increased, the TiO ₂ content in the slag gradually decreased, but there was no change after a certain time. Was measured. That is, it was found that the amount of Ti saturation in the molten iron was about 5% (22) based on the TiO ₂ , and was measured to be about 23 attainment of saturation.

It can be seen from this that even if the amount of TiO ₂ is excessively high, the amount of Ti reduced into the molten iron is determined, and the contact time between slag and molten iron is required for at least 10 hours to sufficiently reduce the amount of TiO ₂ . That is, the TiO ₂ input should be adjusted based on the slag 6%, which is similar to the actual blowing speed 20kg / min. In addition, in order for the blown-out TiO _{2 to} have a sufficient reduction opportunity, it is necessary to discontinue use of the starting point of the blown point at least 10 hours.

Figure 3 shows the results of measuring the activity of Ti according to the oxygen partial pressure as a basic condition for forming a combustion zone in front of the tuyere during spectroscopic injection.

As the oxygen partial pressure in the furnace was decreased, the activity of Ti increased exponentially, and when the oxygen partial pressure was below a certain level, the activity of Ti rapidly increased (31). In order to minimize the partial pressure of oxygen when blowing TiO ₂ through this, the pulverized coal blowing oxygen was stopped. In addition, in order to improve the dissolving ability of the blown spectroscopy, pulverized coal blowing of the adjacent tuyere was simultaneously stopped.

4 shows the result of measuring the degree of reduction of the amount of Ti reduced in molten iron according to the activity of Ti.

When the Ti activity is 2.0 × 10 ^{−3 or} more, the content of Ti in the molten iron rapidly increases (41), which is an effect that can be secured by adjusting the oxygen partial pressure.

5 shows the result of measuring the relationship of TiC formed according to the Ti content in the molten iron. As the amount of Ti contained in the molten iron was increased, the amount of TiC, the main component of the viscous layer, was also increased proportionally (51) through the measurement results.

6 shows a local erosion situation with the furnace side wall edge that is generally progressed. Locally eroded areas as compared to the healthy edges 6 show a significant reduction in the original construction thickness, which occurs at the bottom 62 of the exit. There are many causes of this phenomenon, but mainly due to poor liquidity of the core coke (64), the melt does not flow smoothly to the opposite exit port (63), it appears to appear because it is delivered by turning to the exit bottom or outer shell. have.

Figure 7 shows the process of forming TiC in the erosion site by the multi-step blowing. The first stage blowing is carried out once through the adjacent bulge 71 immediately above the local erosion part 712, and the starting line at this time utilizes the diagonal direction 713. FIG. At this time, the blowing amount is about 2.5 tons, and a simple adhesion layer 711 is formed.

As a two-stage blowing, blowing is carried out continuously 3 to 4 times at a blowing amount of about 2.5 tons each time through a local erosion site and a trough 72 of 20 ° intervals. At this time, the exit port uses a diagonal direction 723, through which the melt flow 72 inside the melt proceeds in the opposite direction, and then strikes the temporary attachment layer 711 at the erosion part to form a vortex and erosion at the same time. It is stagnant 722 inside the part.

When the melt is stagnant, the external cooling water temperature is adjusted (25 ⇒ 15 ° C or less) to grow carbon lead and TiC formed on the surface.

Fig. 8 shows the actual TiO ₂ spectroscopic blown results and the bottom wall temperature storage by this.

The blow 81 of the first stage was 2.24 tons, and three (82,83) blows were performed for two consecutive days in the range of 2.4 to 2.67 tons after one day had elapsed. From the time point 84 after about 20 hours had passed after the blowing was completed, the temperature of the side edge was rapidly lowered to confirm the phenomenon of stabilization.

By forming a strong viscous layer in the area where the local erosion of the bottom edema progressed by the above method, it is possible to fundamentally solve the problem of the bottom erosion and local erosion which occurs periodically every year, and ultimately increase the thickness of the bottom edge, It can also contribute to stability and longer life of the blast furnace.

The present invention can form a stable viscous layer on the local erosion site with the bottom side edge by blowing the TiO ₂ light in two stages through the tuyere, and changing the corresponding operating conditions. Therefore, it can contribute to the cost reduction of charterers because it can eliminate local erosion problems that occur periodically and prevent opportunity loss in advance. In addition, it increases the thickness of the bottom side edge and has the effect of extending the life of the blast furnace.

Claims (4)

A first step of forming a simple adhesion layer by drawing a tiO ₂ through the air outlet located on the opposite side of the furnace erosion unit and blowing TiO ₂ through the air duct located directly above the furnace erosion unit; Including the second step of blowing the TiO ₂ 3 to 4 times through the air hole spaced 20 ° away from the erosion portion and at the same time through the exit port located in the opposite direction of the erosion portion, the melt inside the temporary attachment A method of forming a bottom viscous layer by multi-step injection of titanium oxide spectroscopy into a blast furnace vent characterized in that the temporary adhesion layer is grown while stagnating in the erosion part while forming a vortex by hitting a layer. The method of claim 1, TiO ₂ input amount of the first step and the second step is 2.5 tons, method of forming a bottom viscous layer by multi-stage injection of titanium oxide spectroscopy into the blast furnace tuyere. The method of claim 1, The method of claim 2, wherein the cooling water temperature is 15 ° C. The method of claim 1, The method of forming a bottom viscous layer by multistage blowing of titanium oxide into the blast furnace, characterized in that the supply of oxygen in the second step to stop the supply of oxygen, and the injection of the pulverized coal in the adjacent tuyere.