JPS59143012A - Manufacture of steel in bottom or top and bottom blowing converter - Google Patents

Abstract

PURPOSE:To manufacture advantageously steel only from solid materials contg. iron by bringing a converter provided with bottom blowing tuyeres down to the horizontal state, charging the solid materials contg. iron, melting them with a burner, uprighting the converter, and carrying out conventional scrap melting and refining. CONSTITUTION:A bottom or top and bottom blowing converter 5 provided with bottom blowing tuyeres 6 is brought down to the horizontal state, and a prescribed amount of solid materials contg. iron such as scraps 3 is charged into the belly of the converter 5. While protecting the tuyeres 6 by cooling, a burner 7 for melting is put in the converter 5, and the scraps 3 are melted to form a prescribed amount of a molten scrap bath. The converter 5 is then uprighted, and a refining gas or the gas and a powdered slag forming material are blown from the tuyeres 6 to refine the molten scrap bath. Thus, steel is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a tuyere for supplying refining gas to a furnace.
This article relates to the Jl method for producing steel using a master blowing method or a converter blowing furnace, and is particularly concerned with a steel manufacturing method in which steel is produced using only solid iron-containing materials such as scrap.

In converter 1 steelmaking, steel is mainly charged with molten iron source to refine steel. As sources of this molten iron, hot metal from blast furnaces and molten iron from electric furnaces are generally used, and solid iron sources such as scrap are put into a converter during the refining process and blowing is performed. .

However, it is difficult to blow with a scrap ratio exceeding a certain limit in normal blowing. As shown in FIG. 1, in the top-blown converter 1, when blowing is performed at a high scrap ratio, the oxygen supplied from the lance 2 is interfered with by the scrap, and the reaction with the molten iron becomes key. Even if coke, coal, etc. are introduced from above the furnace to compensate for the heat source, the molten iron will only be burned on top of the scraps and the heat will be transferred slowly to the molten iron, resulting in extremely poor thermal efficiency. However, in a converter having a bottom blowing tuyere, there is a method, as known from Japanese Patent Publication No. 56-8085, in which pulverized coal or pulverized coke is charged through the tuyere to raise the temperature of the molten iron and melt the scrap. If this method is applied, blowing becomes possible even at a high scrap ratio. However, even with this method, a molten iron source is required for the best start, and this iron source can be a molten iron source from a mendo or electric furnace as mentioned above, or a molten iron that has been left behind. There is a method of using it again for the next blowing, but blast furnaces, electric furnaces, etc. may not have such equipment, or there may be restrictions on the operation of these equipment. In addition, in the latter case where the remaining molten iron is retained, there is a time limit until the next blowing, and both methods have the disadvantage of being inflexible.

In addition, as in Japanese Patent Publication No. 56-51207, scrap is preheated and melted by using a bottom blowing converter with the furnace upright and supplying liquid or gaseous fuel as a heat source and combustion supporting gas such as oxygen from the bottom. There is also a method of layering, but the blades are blocked by the charged scrap, it takes a long time to melt, and the blowing gas becomes uneven, resulting in the blades being blocked (-).
The melting loss becomes significant. In addition, scraps may hit the pit and deform the tuyeres, or scraps may collide with the hearth bricks.
There was an entry point where the hearth bricks cracked, accelerating hearth damage and significantly reducing hearth life. Also, converter is elj
L: The method of melting scrap in a pond furnace and charging it into a converter requires melting equipment for that purpose;
Also, there is a disadvantage that the temperature of the molten metal decreases significantly during transport and charging into the converter.

The present invention provides a converter steel manufacturing method that uses a converter with a bottom blowing surface, uses only solid iron-containing materials such as scrap without using a molten iron source, and solves the above-mentioned conventional problems. The gist of this method is to invert a converter with a bottom blowing surface to a horizontal position, heat the solid iron-containing material charged in the belly of the furnace with a burner, and melt it while the tuyere is removed. After melting the molten iron source bath, converter? This is a steelmaking method in which ordinary scrap melting and blowing is performed in an upright position.

Next, the uninvented steel manufacturing method will be explained in detail.

A method of blowing starting from a fully densified solid iron source material using a bottom-blowing or top-bottom-blowing converter equipped with bottom blowing, in which the converter is turned over horizontally. Then, a predetermined amount of solid ferrous material such as scrap is charged from the furnace mouth into the belly of the furnace, and then a melting burner is inserted into the furnace to heat and melt the solid ferrous material to form a predetermined amount of molten bath. Form.

In this way, is the molten bath inside the furnace belly? After the formation, the solid ferrous material or the solid ferrous material and the solid carbon-containing material are charged once or in several stages as necessary,
This is a method of melting steel in the same way as normal bottom blowing or bottom blowing converter blowing, by blowing purified gas or purified gas together with powdered slag material through the bottom blowing side of the converter in an upright position. .

Below, the configuration of the method of the present invention will be explained in detail based on the Hyogo-style Meisho Kama.

The present invention is a converter having a permanent blowing blade 1, in which the converter is turned over horizontally and solid iron materials such as scrap, cold pig iron, sponge iron, and pellets are charged into the furnace belly. A burner is inserted into the furnace to supply and melt a combustion-supporting gas with a fine ratio of fuel and oxygen, and with this great consideration, the solid ferrous material charged is melted and then the required G is produced. Scrap coke and the like are charged into the furnace, and with the furnace in an upright position, refining gas is blown into the furnace through the tuyeres, and 1i111 is melted by normal blowing.

If tJ steel is to be obtained only from the scrap enamel charged into the furnace belly, the furnace is left upright and blowing is performed to melt the steel. In addition, in order to melt the molten steel further north, additional scrap is charged before it is erected, and in order to secure the heat required to melt the scrap, 1d-type carbon-containing materials such as coke and coal are added. Melt the necessary substances at the same time or by adding them from the top of the furnace! Melt so that the amount is a. First, since the mother molten iron is limited, if multiple pieces of scrap are charged at once,
Since there is a risk that the mother molten iron may cool too much and solidify, it is effective to repeat the blowing and additional charging several times.

FIG. 2 is a schematic diagram showing Embodiment 2, and is a schematic diagram of melting of a solid ferrous material in a converter having a double blowing pattern. A bottom blowing tuyere 6 is provided at the bottom of the converter 5 which is placed in a horizontal state, and when scrap 3 is charged into the belly of the converter, it is passed through the melting bar 7 and [Apply heat from Step 4 to melt the scraps. As a melting burner,
As shown in Fig. 2, several jet nozzles 8 are installed so that the high-temperature flame hits the scrap uniformly, and the melting burner is water-cooled to avoid the high temperature inside the furnace. The fuel may be liquid fuel such as heavy oil, light oil, or kerosene, or gaseous fuel such as propane, LPG, or LNo, or solid fuel such as coke breeze or pulverized coal.Generally, gaseous fuel The input heat temperature is small and melting takes time, and large conveyance equipment is required to obtain a large amount of heat.Liquid and solid fuels have a large amount of heat transfer ability, but liquid fuel has a large transfer pressure loss and is expensive. Therefore, it is economically advantageous to use inexpensive solid fuels such as coke breeze and pulverized coal.When melting scrap using fuel and combustion-supporting gas containing oxygen, the thermal efficiency is approximately In other words, when the scrap is melting, the temperature of the scrap is approximately 1500°C, and the temperature of the generated exhaust gas is around 200°C. Because it melts at around 1500°C, the molten iron stays at about this temperature until the scrap is completely melted, and therefore the exhaust gas that is supposed to give heat to the molten iron is also kept at an almost constant temperature. Considering that, thermal efficiency can be estimated as follows.

η'iEfficiency considering heat radiation from the converter [-]q; When fuel burns in a completely adiabatic state,
cat7kg) Op + Exhaust gas specific heat (kca (/9)
°C] TGt exhaust gas temperature [°C] At this time, q is calculated using the following formula.

(1=Q/Go...
・(2) Q+Fuel heat generation fik CkoalAC9)G
o + Amount of gas generated from 1 kg of fuel [now gas fig fuel] This G. Naturally, this varies depending on the oxygen ratio in the combustion-supporting gas.

Figure 8 shows scrap melting 1 when coke powder is used as the heat source.
'Thermal efficiency at F1 is shown using the oxygen ratio in the combustion-supporting gas as a parameter. However, in this case, η'=0.9.

As can be seen from FIG. 8, as the oxygen ratio in the combustion-supporting gas increases, the thermal efficiency increases. A low ratio reduces thermal efficiency and is quite wasteful in terms of fuel.

Considering the case of heating with electricity, etc., the amount of mind is 860.
The power plant efficiency is around 40% at kca7/kW-H,
If the thermal efficiency from electricity to scrap etc. is 80%, then 1
In order to give 000kCatD heat, the original amount of heat is 1 1000 x - 3125 [kca17
1000 koa, l] is required. On the other hand, considering the thermal efficiency shown in Figure 3, it is around 45%, which is almost the same efficiency as electricity. The MW ratio at this time is around 50%, and 50%
By burning with combustion-supporting gas containing oxygen,
Melting can be done with a lower input of hot air than when melting with electricity.

On the other hand, since the heat dissipated from the converter furnace body and the heat dissipated from the bricks are almost constant, the heat input per unit time needs to be larger than a certain level. This largely depends on the size of the converter, so it is not possible to specify a general number.

As mentioned above, by using a combustion-supporting gas containing more than 50% oxygen, it is possible to use fuel such as coke powder. By charging scrap into a converter and burning it, it is possible to melt scrap with a lower amount of heat than when using steam. Furthermore, as shown in FIG. 2, the scrap can be melted by charging it into the belly of the bottom-blowing converter.

In addition, since the scrap is charged into the furnace, there is no damage to the furnace bottom due to scrap charging or melting of the blade when melting the scrap.Also, the blade is resistant to heat from the burner. By flowing a small amount of gas through L, cooling of j]) can also be achieved.

By using the above technique, it is possible to melt scrap in a bottom blowing converter.

On the other hand, when performing combustion 3 with a melting burner, complete combustion (0+0
2-) 002 + 8080 kca, l) ka is desirable from the standpoint of effective energy use, but in that case, 1°01 to 1.05 times the theoretically required amount of oxygen must be delivered. It is difficult to achieve complete combustion.

In addition, the rate at which coke powder, pulverized coal, etc. are supplied as fuel fluctuates, and the rate at which oxygen is supplied tends to be unable to completely follow this change. Under such conditions,
Excess supply of oxygen is likely to occur, causing damage to the refractories of the converter and acclimatization of the iron. Therefore, if scrap to be melted and coal/coke as a carbon source are charged into the furnace in advance, even if an excess of oxygen is supplied, the carbon already exists in the furnace. Since it is consumed by combustion, there is no effect on breathing due to excess oxygen, and moreover, it is possible to obtain effective heat pickling.

Furthermore, if coal or coke is present in the furnace in advance, even if iron oxidation occurs, the reaction Fe○+C→Fe+OO will occur, making it possible to reduce iron oxide.

In this way, if a carbon source is made to exist in the furnace in advance, scrap melting using a gas with a high fuel/oxygen ratio can be used to produce actual IAu very efficiently.

Furthermore, if the seven-person gangway 3 and the carbon source 9 (coal or coke) are charged in layers in the shape T shown in Figure 4, the molten iron on the charging surface will pass through the coke/coal layer and into the furnace. As it passes through this coal seam, the hot metal gradually melts into the riverbed, which lowers its melting point, making it easier to melt in the liquid phase and retain the iron. Become.

Examples will be described below.

Example 1 In a converter of 85 having a bottom blowing tuyere, scrap was transferred to 80 tons and cao B4O0 in the form shown in Fig. 2.
After charging the melted refractories in the furnace, refractory powder was molten or semi-molten and hot-blown using a flame gunning device used for repair. An attempt was made to melt the scrap by supplying 7 Hm of N2 for conveying coke breeze at this time.
/min. In addition, 8N is used as the tuyere cooling gas.
m3//min was flowed. When the temperature of the outer tube of the siding was measured, it was aoo'''C-400°C, indicating that it had been sufficiently cooled.The changes in the humidity of the exhaust gas generated from the converter at this time and the humidity in the steel bath were As shown in the figure. As time passes, the exhaust gas temperature and scrap temperature rise, but the scrap temperature reached 1500°C around 20 minutes. This is thought to be because some of the scrap began to melt. The rise in exhaust gas temperature became smaller, and the humidity was around 2000'C until the 85th minute.After 35 minutes, both the exhaust gas humidity and the scrap humidity rose, indicating that all the scrap had melted. Therefore, the heating was stopped after 38 minutes, but the temperature at that time was 1580°C.To heat scrap at room temperature to 1580'C with IjO, 10 x 1. Okcal is required, and this Calculating the efficiency from this results in the following.

(kca4Ap) (minutes) The above experiment revealed that it melts with a thermal efficiency of 55.8%.

Furthermore, the temperature of the tuyere did not exceed 4100'C during scrap melting, and it was possible to sufficiently protect the tuyere.

Approximately 1 ton of coke and 3 Ut of scrap were immediately charged into the melted scrap, the furnace was erected, and scrap melting and blowing was started. At this time, the oxygen delivery rate is 80% from the bottom blowing tuyere.
Nm8/min, 140 Nm87m from top blowing lance
It was 1n. In this state, small coke with a diameter of 10 to 20 mm was introduced from the top of the furnace six times at a rate of 1 ton, and the coke was heated for 25 minutes (with 1 feed).
At the time of blowing, the molten steel in the furnace was analyzed and the humidity was measured, and it was found to be C8. The oxygen flow rate was kept at the same value, and coke was introduced from the furnace king 10 times at a rate of 1.0 Lt.At the time of blowing for about 45 minutes (oxygen flow rate 10 (IUONm)), the molten steel was analyzed and When 7fl temperature was carried out, the temperature was 1600"C.

GO, 5%. By further blowing in this state for 2 minutes, it was possible to obtain 1.700'CD, 0.5% molten steel. The metal yield by this method was 85%. During blowing, Ca is supplied from the tuyere of the furnace along with blowing gas.
Blend was injected to give a basicity of 8.

Example 2 A top-bottom blowing converter was used for 85, and when the furnace was turned over horizontally and raw materials were charged into the return section of the furnace, scrap and coke were charged in layers. At this time, first, 1 ton of coke is charged uniformly into the furnace belly. Next, 10 tons of scrap is divided into 4) 1j pieces and uniformly charged into the furnace belly. Once again, 9 is uniformly charged into coke 7.500, but in order to layer coke and scrap, it is necessary to
A relatively large coke particle size of 20 to 39 mm is desirable.

Scrap and coke were again charged alternately throughout the process, and then 8 ut of scrap and 2 t of coke were charged and scrap melting started. The alternating charging of scrap and coke is shown in the schematic diagram in Figure 4. Since the coke contained 5 in2 of coke, 1 part of CaO powder was charged to prevent the occurrence of refractory problems.

When melting scrap using a flame spray burner, the following conditions apply: supply of coke breeze M W f: 7 u l
cg/min, 7 Nm as coke carrier gas
N2 gas was used at a flow rate of /min, and 115 Hm"7 ml was supplied as combustion O2. Melting operation was carried out for 38 minutes under the above conditions, and a total of δ1-2°7t of coke, 437ONm of B Oxygen (oxygen excess ratio].0)
It was used. The molten iron at this time is saturated with carbon at 1580°C, 0-41°3%, Si, -0.05%, and this carbon effectively acts as a heat source in the continuous blowing process. Table 1 shows the slag analysis values after melting when coke was charged alternately and the slag analysis values after melting when only scrap was charged.

Table 1 Slag composition after scrap melting (%
) When coke and scrap are charged alternately during scrap melting, the T and RE concentration in the slag is 8.0%.
This is low, indicating that FeO is reduced by carbon. Therefore, there is less damage to the refractory walls.

Using the mother hot metal produced in this manner, 30 pieces of scrap are then charged, the furnace is set upright, and scrap melting and blowing is started using the bottom tuyere and top blowing lance. The conditions at that time were that the blowing force from the bottom blowing surface was 90 Nm.
/min, and the oxygen supply rate from the top blowing lance is 170 N.
Oxidation is carried out at a rate of 10 to 2 m/min from the top of the furnace during blowing.
500M of small coke with a diameter of 0 was introduced into each mouse. The analysis value of the molten steel in the furnace at the time when the blowing cycle was carried out for 32 minutes under such conditions F and the total amount of oxygen supplied was 865ONm13E. The temperature was 0.6% molten steel, and the warm temperature was 1.650'C. Scrap 40 again here
t was finally charged and melt blowing was performed. The conditions at this time are that the oxygen feeding rate remains the same, and as before, 500 kg of coke is added from the top of the furnace 7 times, and the feeding interval is strictly maintained at 2 to 3 minutes to prevent coke combustion. By maintaining a balance with the oxygen supply rate, melt blowing was carried out without extreme oxidation of iron. In the final melting and blowing, the total amount of coke input was 12t1, the blowing time was 47 minutes, and the total amount of oxygen used was 10,000 Nm.
It was used.

In the blowing process described so far, all scrap is used as the iron source, so compared to the 12% 5i02 content in coke, only the amount necessary to maintain basicity 3 is required. Only quicklime was used, and the amount of quicklime used in each process was totaled to 8. The final solution M was 16
50'C,O-0.06%, and the total B metal yield was 89%.

Although the scrap and melting ratios in the furnace-c are the same,
In a converter in which scrap and coke were alternately charged, the erosion rate of the furnace refractory was 2.2 mr5/ch;
2.8 rrun for the converter body charged only with scrap 2
/ah. Figure 6 shows a comparison of the state of wear and tear on the refractories in the furnace when the converter operation was stopped. Figure 6 (A
) is a case where alternate charging of coke and scrap is applied.
(B) is the furnace profile without application, but in the case of (B), the area around the pool is extremely worn out due to Fe○ generated during scrap melting. However, by applying alternate charging of coke and scrap as shown in (A), it is possible to operate the furnace in a uniform state of wear and tear, and the fire resistance is improved. We were also able to reduce the physical unit consumption.

As explained above, according to the method of the present invention, unlike conventional scrap melting, damage to the furnace bottom and siding can be avoided, and damage to the refractories in the refractory section of the furnace can also be suppressed. When coke and scrap are charged alternately, the effect is even more remarkable, and steel can be produced extremely advantageously only from solid iron-containing materials such as scrap.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a high scrap ratio (υ melting) in a top-blown converter, Figure 2 is a schematic diagram of an example of scrap melting in a converter with bottom-blowing windows, and Figure 3 is a schematic diagram of coke breeze melting. The graph shows the change in thermal efficiency with respect to the oxygen ratio in the combustion-supporting gas during combustion.The fourth figure is a schematic diagram showing the state of alternating charging of scrap and coke.Figure 5 shows the change in exhaust gas temperature and scrap humidity during the experiment. Figure 6 is an explanatory diagram showing the balance of bricks in the furnace when the furnace is shut down. J... Top-blown converter 2... Lance 3... Scrap 4... Molten iron 5 ... Converter with bottom tuyere portion 6... Window 7... Melting burner 8.
...Nozzle 9...Coke]0...
Refractory brick l]... Locally damaged area. Figure 5 fo 20 30 110 50 hours [
Figure 6 (A) CB)

Claims (1)

[Claims]] In a steelmaking process for producing steel by charging solid iron-containing material using a bottom-blown or top-bottom-blown converter equipped with bottom blowers, the Hokki converter is placed in a horizontal state. A predetermined amount of the solid ferrous material is charged into the furnace 11, and while the tuyeres are cooled and protected, a burner is inserted into the furnace to melt the solid ferrous material. After forming a molten bath of a predetermined amount of ferrous material, the converter is turned upright and the 'Fi
A steelmaking method using a top-bottom blowing converter with two bottom-blowing or top-blowing converters. During steel manufacturing, a bottom blowing converter is charged with solid ferrous material to form a surface (in this case, the converter is turned over horizontally, a predetermined amount of the solid ferrous material is charged into the belly of the furnace, and the Insert the melting burner into the furnace while cooling and protecting the mouth to melt the solid iron-containing material 1.
After melting and forming a molten bath of a predetermined amount of ferrous material, 1
As described above, the converter is held in an upright position while charging 1iffl type ferrous material and solid carbon-containing material several times.
A steelmaking method using a bottom blowing or a top blowing converter, which is characterized by blowing refining gas or powdered slag material together with the refining gas to remelt steel. Claims 1 or 2, characterized in that solid 9J material and solid iron-containing material are alternately charged into the furnace 1 recess of a converter that has been turned over horizontally. 7 methods of making juice using a 1-degree blower or an L-bottom blower converter.