JPH07316674A - Recycling method of rolling sludge - Google Patents

Abstract

PURPOSE:To make effective use of the rolling sludge consisting of an oil, water and an iron oxide generated in the continuous casting process and the rolling process as the iron source and the heat source. CONSTITUTION:The rolling sludge is charged in a stirring bath 2, and water is fed from a water feeding piping 4 to the stirring bath where the rolling sludge is charged, and the steam is fed from a steam feeding piping 5 to heat the rolling sludge. After the kinematic viscosity of the rolling sludge is made to about 10mm<2>/s(10 centistokes) by stirring the sludge with a stirring blade 3b of a stirring device 3, the rolling sludge of the amount obtained based on the theoretical combustion temperature before the tuyere, after the viscosity is adjusted, is forcibly fed by a pump 7a through a sludge feeding piping 7 communicating from stirring bath 2 to the tuyere 8, and the rolling sludge can be blown from the tuyere 8 to the blast furnace without adverse effect on the operation of the blast furnace, and the effective use of the rolling sludge as the iron source and the heat source can be achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling rolling sludge generated in a continuous casting process, a rolling process, etc., and particularly, by blowing the rolling sludge into a cold iron source melting furnace,
The present invention relates to a method for recycling rolled sludge that can reduce the operating cost of a cold iron source melting furnace.

[0002]

2. Description of the Related Art A large amount of rolling sludge composed of iron oxide, water and oil is generated in a continuous casting process or a rolling process in an iron mill. The rolling sludge is COS, CS ₂ , SO ₂
It emits a foul odor and is difficult to use as it is. Therefore, a recycling method of drying, degreasing, and blowing the dried and degreased rolled sludge into the blast furnace from the tuyere is considered.

A method for treating a treated product containing iron is disclosed in, for example, Japanese Unexamined Patent Publication No. 5-9529. Hereinafter, this will be described with reference to FIG. 5 of the flow sheet diagram with the same names and reference numerals described in the specification, and the dust generated from the converter 10 and the shaft furnace 1 will be wet dust collector 8. , 8 and the dust collected is separated by a thickener 7 into solids. Then, the wet slurry dust extracted from the bottom of the thickener is dehydrated by the dehydrator 6 to form a cake, and a part thereof is supplied to the furnace top charging / receiving hopper 11 provided at the top of the shaft furnace 1 to supply the shaft furnace 1 Throw in.

On the other hand, the remaining cake is introduced into a drying device 5, and is made into dry powder by combustion exhaust gas, etc., and is carried out to a powder supply hopper 4 by a transportation method such as air flow transportation, and upper and lower hot air provided in a shaft furnace 1 By blowing with hot air from the upper tuyeres 3 of the tuyeres 2 and 3, the treated material containing iron is effectively used as an iron source. Reference numeral 9 provided above the converter 10 is an exhaust gas recovery device.

[0005]

DISCLOSURE OF THE INVENTION As described above, the iron-containing treated product is dehydrated to be powdered and then is rolled into a slurry form composed of iron oxide, water and oil so as to be blown into the blast furnace from the tuyere. In the case of sludge, it was considered to be used as an iron source after being dried and degreased. However, since the equipment cost and running cost for drying and degreasing the slurry-like rolled sludge increase, it is actually preferable to save resources and energy, but it is actually stuck at the place of occurrence. . Needless to say, pneumatic transportation of pulverized coal and pumping technology of heavy oil by a pump have been established, but transportation of highly viscous slurries consisting of iron oxide, water and oil can be achieved by the above transportation technology. Part of that is that there was nothing.

Therefore, the present invention uses a rolling sludge as an iron source,
It is to provide a method of recycling rolling sludge that can be used as a heat energy source.

[0007]

According to the present invention, if the viscosity of the rolling sludge can be made low, it becomes possible to pump the rolling sludge by a pump, and further, the amount of the rolling sludge blown from the tuyere can be controlled. It was thought that it would be possible to recycle the rolling sludge while preventing it from destroying the basic form of the countercurrent heat exchanger of the blast furnace if it is set based on the theoretical combustion temperature before the tuyere.

Therefore, the feature of the means adopted by the method for recycling rolling sludge according to the present invention is that the rolling sludge is put into a stirring tank, and the rolling sludge is put in advance in the rolling sludge put in the stirring tank. Water is added to reach the set water content and temperature, and the viscosity of the rolling sludge is adjusted by stirring while warming, and the rolling sludge after viscosity adjustment is pumped and the theoretical burning temperature before tuyere is calculated. The amount of rolling sludge per unit time obtained based on this is blown into the cold iron source melting furnace from the tuyere.

[0009]

Therefore, according to the method for recycling rolled sludge according to the present invention, the rolled sludge put into the stirring tank is
By adding water, heating, and stirring, the viscosity of the entire rolling sludge in the stirring tank is adjusted to be uniform and pumpable with a pump. Then, the rolling sludge after viscosity adjustment is blown into the cold iron source melting furnace from the tuyere, but the amount of rolling sludge blown from the tuyere is obtained based on the pre-tuyere theoretical combustion temperature calculation. The basic form of the countercurrent heat exchanger of the cold iron source melting furnace does not collapse.

[0010]

EXAMPLES The following is an example of rolling sludge viscosity adjustment / blowing equipment for realizing the rolling sludge recycling method of the present invention, in which rolling sludge is blown into a blast furnace, which is a type of cold iron source melting furnace. Figure 1 of system diagram showing viscosity adjustment and blowing equipment, Figure 2 of viscosity relationship diagram with temperature of rolling sludge, Figure 3 of viscosity relationship diagram with rotation speed of stirring blade of rolling sludge rotator, tuyere 1 This will be described with reference to FIG. 4 which is an explanatory diagram of the relationship between the blowing amount of the rolling sludge and the pre-tuyere combustion temperature.

First, referring to FIG. 1, the structure of the rolling sludge viscosity adjusting / blowing facility 1 will be described. Reference numeral 2 in the figure is a stirring tank into which the rolling sludge is fed from the mixer car M. The stirring tank 2 includes a motor 3a provided at an upper portion thereof, and a stirring blade 3b for rotating the sludge in the stirring tank 2 by the motor 3a at a constant rotation number around a vertical axis. 3 is provided.

Further, a water supply pipe line 4 having a plurality of valves is communicated with the stirring tank 2. One of the plurality of valves is an open / close valve 4a, which is closed when the current value of the motor 3a is equal to or less than a preset specified current value, but opens when the specified current value is exceeded. Configured to be valved. Further, in the stirring tank 2, a steam supply line for supplying steam to heat the rolling sludge when the temperature of the rolling sludge inside measured by the thermometer T is lower than a preset temperature. 5 are in communication. A well-known ventilator 6 for adjusting the internal pressure of the stirring tank 2 is provided between the water supply pipe line 4 and the stirring device 3.

On the other hand, a sludge supply pipe 7 for pumping the rolling sludge from the stirring tank 2 communicates with a tuyere 8 provided in a blast furnace (not shown). A pump 7a for pressure-feeding the rolling sludge is provided in the sludge supply pipe 7, and the pump 7a has a rotational force adjusted by the measurement pressure of a pressure gauge P that measures the pressure on the discharge side. It is configured to be rotated by the drive motor 7b.
Further, on-off valves 7c, 7c operated by compressed air are provided between the pressure gauge P and the tuyere 8.

A sludge return pipe 9 in which a pressure control valve 9a is interposed branches from a portion of the sludge supply pipe 7 between the pump 7a and the pressure gauge P, and a non-branching side is the stirring tank. It communicates with 2. In other words, the sludge return pipe 9 has the same function as the relief pipe in the hydraulic circuit, and the pressure control valve 9a corresponds to a relief valve. The rolling sludge is supplied to the tuyere 8 while returning the rolling sludge from the sludge return pipe 9 to the stirring tank 2.

By the way, the viscosity adjustment of the above-mentioned rolling sludge
The blowing facility 1 is configured based on the following. That is, the rolling sludge changes depending on the temperature and the mixed state of iron oxide, water and oil. For example, the rolling sludge A having 29.7% by mass of iron oxide, 37.2% by mass of water, and 0.17% by mass of oil is shown by a solid line, and 31.9% by mass of iron oxide.
The rolling sludge B having a water content of 35.8% by mass and an oil content of 0.13% by mass is shown by a broken line, and the viscosity change with respect to the temperature of the rolling sludge while stirring by rotating the stirring blade at 20 rpm and holding at a temperature of 20 ° C. The relationship between the change in viscosity with respect to the number of revolutions of the stirring blade and the pre-tuyere combustion temperature with respect to the amount of rolled sludge blown into the blast furnace, which represents the uniformity of the mixed state of iron oxide, water, and oil in the rolling sludge, It is as follows.

First, regarding the viscosity of the rolling sludge with respect to the temperature, the vertical axis represents the viscosity η of the rolling sludge on a natural logarithmic log η scale, and the horizontal axis represents the temperature (° C.) of the rolling sludge, as shown in FIG. The higher the content of, the higher
It decreases as the temperature increases. Next, regarding the viscosity of the rolling sludge with respect to the rotation speed of the stirring blade, the vertical axis represents the viscosity η of the rolling sludge on a natural logarithm log η scale, and the horizontal axis on the rotation speed (rpm) scale of the rotary blade, as shown in FIG. , The higher the content of iron oxide, the higher, but the higher the temperature, the lower
Moreover, the number of rotations of the rotary blade is significantly reduced between 0 and 10 rpm. In other words, these phenomena are such that if the water content is adjusted, the temperature is adjusted by heating, and if the iron oxide, water and oil are well mixed by stirring, the rolling sludge can be adjusted to a low viscosity and pumped by a pump. It suggests that you can do it.

When the rolling sludge adjusted to have a low viscosity is blown into the blast furnace, it naturally has a bad influence on the temperature inside the blast furnace. Therefore, the blowing amount of the rolling sludge that can be blown into the blast furnace without any bad influence is obtained. I decided. That is, the change in the theoretical burning temperature before the tuyere with respect to the blowing amount of the rolling sludge is
The vertical axis is the theoretical combustion temperature before tuyere (° C), and the horizontal axis is the blowing amount of rolling sludge (t / h / piece). , Also, the one with a large injection amount lowers the furnace temperature, but in this case,
Blowing amount of rolling sludge per tuyere is 1.0t /
If it was h, it was found that there was no hindrance to the operation of the blast furnace. Of course, the amount of the rolled sludge blown depends on the capacity of the blast furnace.

In the following, in the viscosity adjusting / blowing equipment 1, the case where the viscosity-adjusted rolling sludge is blown into the blast furnace from the tuyere 8 will be explained. When the rolling sludge is fed from the mixer car M into the stirring tank 2, The stirring blade 3 is driven by the motor 3a.
b is rotated, the rolling sludge is agitated, steam is supplied from the steam supply pipe line 5 based on the temperature measured by the thermometer T, and the temperature of the rolling sludge is adjusted. Meanwhile, the stirring blade 3
When the current of the motor 3a for rotating b exceeds a specified current value, the on-off valve 4a is used to reduce the viscosity of the rolling sludge.
Is opened and water is supplied from the water supply pipe line 4. If the temperature decreases due to the water supply, steam is supplied from the steam supply pipe line 5 in accordance with the temperature decrease, and the viscosity of the rolling sludge is, for example, 10 mm ²
Add water, heat, and stir until it reaches about 10 s / s (10 centistokes). The viscosity of the rolling sludge may be pumped by a pump, and is not limited to the value of the viscosity itself.

When the viscosity of the rolling sludge is adjusted in this way, the pump drive motor 7b drives the pump 7a.
Is rotated, the opening of the pressure control valve 9a is adjusted so that the rolling sludge can be supplied from the tuyere 8 to the blast furnace per unit time, and the opening / closing valves 7c and 7c are opened to roll a predetermined amount of rolling. Sludge is blown into the blast furnace through tuyeres 8. By the way, the operating conditions for blowing the rolled sludge after the viscosity adjustment into the blast furnace are as shown in Table 1.

[0020]

[Table 1]

When the rolling sludge whose viscosity has been adjusted to have a low viscosity is blown into the blast furnace from the tuyere 8 as described above, the rolling sludge blown in the raceweed portion of the blast furnace is C
Upon contact with O gas, the iron oxide is reduced to iron and melts, and the molten iron is mixed with the hot metal that continues to be dripped from the upper part of the blast furnace and taken out as pig iron from the taphole. Further, the oil content contained in the rolling sludge reacts with the high temperature air blown from the tuyere 8 to form carbon monoxide, that is, reducing gas, while the water content is decomposed in the racewey portion of the blast furnace and React with the carbon to form a reducing gas such as hydrogen gas or carbon monoxide, and both of these oils and water contribute to the reduction of iron oxide. The odorous gas such as COS, CS ₂ and SO ₂ contained in the rolling sludge is released into the atmosphere through a dust collector provided in the blast furnace.

According to this embodiment, the rolling sludge having a low viscosity due to the viscosity adjustment is pumped as described above, and the amount of the rolling sludge based on the theoretical burning temperature before the tuyere is fed from the tuyere 8 to the blast furnace. Since it is blown into the blast furnace, it prevents the basic form of the countercurrent heat exchanger of the blast furnace from breaking down, and
Unlike the conventional method, it is possible to effectively recycle the rolling sludge that remains in the place of occurrence without drying and degreasing the rolling sludge, saving resources,
An extremely great effect can be obtained for energy saving.

In the above, the case where the viscosity-adjusted rolling sludge is blown into the blast furnace has been described as an example, but it can be blown into a cupola which is a kind of a cold iron source melting furnace. However,
Since the cupola is extremely small compared to the blast furnace, even if it is effective in saving resources and energy, the amount of recycled rolling sludge is extremely small. For example, thousands of tons / month generated from a steel mill Completely treating the rolling sludge by recycling is impossible.

[0024]

As described above, according to the method for recycling rolling sludge according to the present invention, the rolling sludge adjusted to have a low viscosity by water addition, heating and stirring is pumped by a pump,
It is possible to continue blowing into the cold iron source melting furnace from the tuyere without destroying the basic form of the countercurrent heat exchanger of the cold iron source melting furnace. The rolling sludge can be recycled as an iron source or a thermal energy source without requiring facility costs and running costs for treatment, which is extremely effective in saving resources and energy.

[Brief description of drawings]

FIG. 1 is a system diagram showing a rolling sludge viscosity adjusting / blowing facility for realizing a rolling sludge recycling method of the present invention.

FIG. 2 is a viscosity relationship diagram with temperature of rolling sludge.

FIG. 3 is a viscosity relationship diagram with respect to the rotation speed of the stirring blade of the rolling sludge rotating device.

FIG. 4 is an explanatory diagram showing a relationship between a pre-tuyere combustion temperature and a blowing amount of rolling sludge per tuyere.

FIG. 5 is a flow sheet diagram illustrating a method of processing a processed material containing iron according to a conventional example.

[Explanation of symbols]

1 ... Viscosity adjusting / blowing equipment, 2 ... stirring tank, 3 ... stirring device,
3a ... motor, 3b ... stirring blade, 4 ... water supply conduit, 4a ... open / close valve, 5 ... steam supply conduit, 6 ... ventilator, 7 ... sludge supply conduit, 7a ... pump, 7b ... pump drive motor, 7c … Open / close valve, 8… tuyere, 9… sludge return line,
9a ... Pressure control valve, P ... Pressure gauge, T ... Thermometer.

Front page continuation (72) Inventor Reiji Ono 2222 Ikeda, Ikeda, Onoe-machi, Kakogawa-shi, Hyogo Pref. Ikota, Kakogawa Research Area, Kobe Steel Co., Ltd. (72) Kazuro Kamei, Kanazawa-cho, Kakogawa Kadogawa Works, Kamido Steel Works, Ltd.

Claims (1)

[Claims] 1. Rolling sludge is put into a stirring tank, water is added to the rolling sludge put into the stirring tank so that the water content and temperature are preset, and the mixture is stirred while heating. The viscosity of the rolled sludge is adjusted by pumping, and the rolled sludge after the viscosity adjustment is pumped, and the amount of rolled sludge per unit time calculated based on the theoretical combustion temperature calculation before the tuyere is melted from the tuyere to the cold iron source. A method for recycling rolling sludge, characterized by blowing it into a furnace.