JPH07215741A - Treatment of steel making waste - Google Patents

Abstract

PURPOSE:To simultaneously and effectively utilize dust which is steel making waste and is industrial waste and reduced slag which is likewise the steel making waste and is the industrial waste. CONSTITUTION:The dust 14 which is the steel making waste and the reduced slag 18 which is likewise the steel making waste are supplied into high-temp. flames 11 and are melted and mixed, by which oxidized slag 29 is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to dust which is discharged during steel making and has little utility value, and dust which is also discarded during steel making and has little utility value. The present invention relates to a method for treating steelmaking effluent suitable for effectively utilizing existing reducing slag.

[0002]

2. Description of the Related Art An electric furnace is often used for melting steelmaking raw materials such as steel scrap, and even in the steelmaking work using such an electric furnace, the furnace capacity is increased and the electric power (UHP) is increased. , Adoption of water cooling box, degassing method (D
H method, RH method) and ladle refining are used together, and a direct current furnace is introduced.

In steelmaking work using such an electric furnace or the like, a dust collector such as a direct type or a building type is installed to prevent air pollution. Is discharged.

Similarly, in the steelmaking work using such an electric furnace or the like, the scrap of steel material charged in is
Steel is discharged after a melting period, an oxidizing period, a slag, and a reducing period. During this period, the steelmaking discharges, that is, the oxidizing slag and the reducing slag are also discharged.

[0005]

Among such steelmaking effluents, dust has a high ZnO content (for example, about 1).
Although it is 0 to 25% by weight, it is the fact that it is hardly reused.

Further, this dust is F oxide as Fe oxide.
The content of e is large (for example, about 50 to 60 wt% as FeO and Fe ₂ O ₃ ), and it is possible to reduce this Fe oxide and recover it as Fe, but it is economical. That is not the case.

On the other hand, the oxidized slag is reused, for example, as a subbase material for asphalt paved roads, but the reduced slag has a large CaO content in its components, and this CaO reacts with water to form CaO (quicklime). ) + H ₂ O (water) → Ca
Since the volume expands about 2 times by changing to (OH) ₂ (slaked lime), when this reducing slag is used as it is as roadbed material, the reaction with rainwater etc. proceeds as the days go by and the volume increases. It is not preferable because it expands and lifts the asphalt pavement surface.

[0008] Therefore, when the reducing slag is used as a roadbed material, the volume is expanded by subjecting it to rainwater, immersing it in a reservoir, or bringing it into contact with steam over a long period of time at a factory site or the like. It is necessary to change to Ca (OH) ₂ as mentioned above, but such aging work is not preferable because it requires a long number of days and requires a large site for accumulation.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is possible to reuse dust, which is a steelmaking discharge, and reducing slag, which is also a steelmaking discharge. It is intended to provide a method of treating certain steelmaking emissions.

[0010]

In the method for treating steelmaking effluent according to the present invention, dust which is steelmaking effluent and reducing slag which is steelmaking effluent are supplied into a high temperature frame to be melted to oxidize slag. It is characterized by being configured,
In the embodiment, the dust and the reducing slag are fed into the high temperature frame of the oxygen burner so as to be melted into the oxidizing slag, or the dust and the reducing slag are supplied in a weight ratio of dust: reducing slag = 1: 0. The feature is that the ratio is set to 1: 3. Note that, here, "dust: reducing slag = 1: 0" means that only dust is melted.

Further, a method for treating a steelmaking effluent according to the present invention for solving the same problem is such that dust, which is a steelmaking effluent, is supplied into a molten reducing slag in a container and melted into an oxidizing slag. In the embodiment, the dust is supplied from the high-temperature frame into the molten reducing slag in the ladle so as to be melted into the oxidized slag, or the ratio of the dust supplied into the molten reducing slag. Is characterized in that the weight ratio is such that dust: reducing slag = 1: 0 to 1: 3. At this time as well, "dust: reducing slag = 1: 0" means that only dust is melted.

Further, when the dust contains a relatively large amount of ZnO, Z contained in the dust
About 1/2 of nO is transferred into exhaust gas, so high ZnO
A high concentration of secondary dust is obtained. Therefore, this ZnO can be recovered and used as a Zn raw material.

[0013]

Since the method for treating steelmaking effluent according to the present invention has the above-mentioned structure, the dust supplied to the high temperature flame and the reducing slag are melt-mixed to obtain the oxidized slag. In addition, dust is mixed and melted with the smelting reduction slag in the container to obtain oxidized slag, and this oxidized slag can be used as a roadbed material for asphalt pavement without aging treatment. Therefore, both the steelmaking emissions, which were conventionally treated as industrial waste, and the reducing slag, which was also the steelmaking emissions and was also treated as industrial waste, are effective at the same time. It can be utilized, and when the secondary dust contains a relatively large amount of ZnO, it will be recovered again as high ZnO dust. Ri and thus which can be effectively used as a Zn material.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a method for treating steelmaking effluent according to the present invention, in which a treatment container 2 is placed on a stand 1 and a gutter 3 of the treatment container 2 is provided. A slag pan (or a water tank) 4 is installed below.

Further, a lid 2a is covered on the processing container 2, and an oxygen burner (pure oxygen burner in this embodiment) 5 penetrating the lid 2a is arranged. , The fuel 7 is fed through the pipe 6, and oxygen (primary oxygen 1
0a, secondary oxygen 10b) 10 is supplied, and when the oxygen 7 burns the fuel 7, the high temperature flame 11 comes out from the tip of the oxygen burner 5.

The oxygen burner 5 has a pipe 12 (1
The powdery dust 14 in the dust hopper 13 is supplied through 2a). At this time, the dust 14 is supplied by a carrier gas (air in this embodiment) 16 fed from a pipe 15. It is supposed to be done by the flow of.

Similarly, the oxygen burner 5 has a pipe 1
2 (12b), the powdery reducing slag 18 in the slag hopper 17 is supplied,
At this time, the supply of the reducing slag 18 is performed by the flow of the carrier gas (air in this embodiment) 20 fed from the pipe 19.

Furthermore, inside the oxygen burner 5,
Cooling water 22 is made to flow through a pipe 21 to cool the jacket of the oxygen burner 5.

FIG. 2 is a bottom view showing the tip portion of the oxygen burner 5, showing a central hole 5a formed at the center,
The pressurized fuel 7 in the atomized state is supplied, the primary oxygen 10 (10a) is supplied from the ring-shaped slit 5b formed on the outer side of the central hole 5a, and a large number of round holes formed on the outermost side. Secondary oxygen 10 (10b) is supplied from 5c.

Further, the carrier gas 1 is supplied from the plurality of elliptical elongated holes 5d formed between the slit 5b and the round hole 5c.
6,20 and powder dust 14 and reducing slag 1
8 is supplied. Although not shown in FIG. 2, as described above, a water cooling structure in which the cooling water 22 flows in the outer portion of the oxygen burner 5 is provided.

In the oxygen burner 5 used here,
The position of the (long) hole 5d for supplying the powder composed of the dust 14 and the reducing slag 18 does not have to be a specific position, and the hole for supplying the powder is formed on the outermost side of the oxygen burner 5. Further, when the fuel 7 is gas, it is not necessary to spray the fuel 7, so that the hole for supplying the powder is formed in the most central portion and the fuel 7 and the oxygen 10 (10a, 10a, 10b) may be supplied.

Further, each dust hopper 13 and slag hopper 17 are provided with valves or rotary feeders 13a, 17a capable of adjusting the flow rate, and the amount of dust 14 and reducing slag 18 supplied is adjusted. You can do it.

Furthermore, slag pan (or aquarium)
A dust collecting duct 27 for collecting the exhaust gas 26 discharged together with the molten slag 25 from the gutter 3 is installed above the gutter 4. Through the dust collecting duct 27, a high Z in the secondary dust is provided.
nO dust is designed to be collected.

In the steelmaking effluent treatment facility shown in FIG. 1, the fuel 7 was burned with oxygen 10 to generate the high temperature flame 11 from the tip of the oxygen burner 5.

The fuel 7 used here is kerosene, and the supplied primary oxygen 10 (10a) and secondary oxygen 10 (10b).
And the theoretical amount of oxygen required for complete burning of kerosene (that is, an oxygen ratio of 1.0).

The amount of air which is the carrier gas 16, 20 is the amount of air containing 5% of the theoretical oxygen amount necessary for complete combustion of kerosene.

Therefore, the high temperature frame 11 at this time
The oxygen ratio with respect to kerosene in the inside is 1.05, and it is in a slight excess oxygen state.

In this state, the steelmaking discharge is shown in Table 1.
The dust 14 of the main component shown in 1 and the reducing slag 18 of the main component shown in Table 1, which is also a steelmaking discharge, are 1: 0,
The openings or rotation speeds of the valves or the rotary feeders 13a and 17a and the flow rates of the carrier gases 16 and 20 are adjusted so that the three kinds of supply ratios of 1: 1 and 1: 3 are provided, respectively. By supplying and melting and mixing the dust 14 and the reducing slag 18 in the high temperature frame 11, and flowing them to the slag pan 4 through the bottom of the container 2 and the gutter 3, the oxidation slag 29 of the main component shown in Table 2 is obtained.
Was collected as. When a water tank was used instead of the slag pan 4, it was possible to obtain granular oxidized slag due to the surface tension of the glass-like fluid.

Further, the ZnO concentration in the secondary dust collected through the dust collecting duct 27 at this time is also shown in Table 2.

[0030]

[Table 1]

[0031]

[Table 2]

The oxidized slag thus obtained can be used as it is or after a slight aging treatment as compared with the conventional reducing slag, as a roadbed material for asphalt paved roads, and high ZnO secondary dust is a Zn raw material. Was reusable as.

As another embodiment, an embodiment different from the above embodiment only in the following points will be described.

That is, the primary oxygen 10 (10
This is a method in which the total amount of a) and secondary oxygen 10 (10b) is supplied while being suppressed to 95% or less of the theoretical oxygen amount required for complete combustion of the fuel 7.

In this case, the oxygen ratio in the high temperature frame 11 becomes 1.0 or less, and CO gas is generated due to lack of oxygen.

This CO gas is Z in the high temperature frame 11.
It reacts with nO as described below to generate Zn gas.

ZnO + CO → Zn (gas) + CO ₂ Therefore, a large amount of Zn gas is present in the exhaust gas, and when this is reoxidized in the dust collection duct 27, the ZnO concentration in the secondary dust tends to increase. Can be seen. This tendency is an advantageous method for ZnO recovery.

As an example, the primary oxygen 10 (10
When the total amount of a) and secondary oxygen 10 (10b) was set to 85% of the theoretical oxygen amount, the ZnO concentration in the secondary dust increased by 7 to 2% from the values shown in Table 2.

However, in this case, since the combustion is not complete, the temperature of the high temperature frame 11 and the amount of heat generated in the high temperature frame 11 are reduced, resulting in the use of a large amount of fuel, which is economical as a method for obtaining oxidizing slag. It was a disadvantage.

FIG. 3 shows still another embodiment of the method for treating steelmaking effluent according to the present invention, which is a ladle 32.
There is a smelting reduction slag 48 at the bottom, and a lid 32a is covered on the ladle 32, and an oxygen burner 35 penetrating the lid 32a is arranged. Fuel 37 is supplied to the oxygen burner 35 through a pipe 36, and oxygen (primary oxygen 4
0a, secondary oxygen 40b) 40 is fed, and the fuel 37 is burned by the oxygen 40, so that the high temperature flame 41 is fed from the tip of the oxygen burner 35.
Is coming out.

Further, the oxygen burner 35 is passed through the pipe 42 and the powdery dust 4 in the dust hopper 43.
4 is supplied, and at this time, the dust 44
Is supplied by the flow of the carrier gas 46 fed from the pipe 45.

Furthermore, inside the oxygen burner 35, a cooling water 52 is made to flow through a pipe 51 for cooling the jacket of the oxygen burner 35.

The dust hopper 43 is provided with a valve or a rotary feeder 43a capable of adjusting the flow rate so that the amount of dust 44 supplied can be adjusted.

Further, the dust collecting duct 5 is provided on the lid 32a.
7 is connected.

In the steelmaking waste treatment facility shown in FIG. 2, the fuel 37 is burned by the oxygen 40 to generate the high temperature frame 41 from the tip of the oxygen burner 35, and the dust which is steelmaking discharge is discharged. 44 is fed into the high temperature frame 41, the molten dust is mixed and melted in the molten reducing slag 48 in the ladle 32, and then the ladle 31 is tilted to be recovered as an oxidized slag (59).

At this time, the molten slag (59) in a molten state
It is possible to obtain granular oxidized slag due to the surface tension of the glassy substance by dropping it into a water tank, and secondary dust having a high ZnO concentration was recovered as a Zn raw material through the dust collecting duct 57.

Oxidized slag (59) thus obtained
However, it was possible to use it as a base material for asphalt paved roads, etc. as it is or by a slight aging treatment compared to conventional reducing slag, and it was possible to reuse high ZnO secondary dust as a Zn raw material.

[0048]

According to the method for treating steelmaking effluent according to the present invention, dust, which is a steelmaking effluent, and reducing slag, which is also a steelmaking effluent, are fed into a high-temperature frame to be melted into oxide slag. Alternatively, since the dust, which is a steelmaking discharge, is supplied into the smelting reduction slag in the container to be melted into the oxidizing slag, the oxidizing slag should be used as, for example, a roadbed material for an asphalt pavement. Therefore, it is possible to effectively utilize the dust, which is regarded as the industrial waste, and the reducing slag, which is also regarded as the industrial waste, at the same time, which is a remarkably excellent effect.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a method for treating steelmaking effluent according to the present invention.

FIG. 2 is an explanatory bottom view showing a tip portion of a burner used in an example of the present invention.

FIG. 3 is an explanatory view showing still another embodiment of the method for treating steelmaking effluent according to the present invention.

[Explanation of symbols]

 5,35 Oxygen burner 7,37 Fuel 10,40 Oxygen 11,41 High temperature flame 14,44 Dust 18,48 Reduction slag 29,59 Oxidation slag

Claims (6)

[Claims] 1. A method for treating steelmaking effluent, characterized in that dust, which is steelmaking effluent, and reducing slag, which is steelmaking effluent, are fed into a high-temperature frame to be melted into oxidized slag. 2. The dust and the reducing slag are fed into a high temperature frame of an oxygen burner and melted into the oxidizing slag.
The method for treating steelmaking effluent according to. 3. The method for treating steelmaking effluent according to claim 1, wherein the supply ratio of dust and reducing slag is dust: reducing slag = 1: 0 to 1: 3 in weight ratio. 4. A method for treating steelmaking effluent, characterized in that dust, which is a steelmaking effluent, is supplied into the molten reducing slag in a container and melted into oxidized slag. 5. The method for treating steelmaking effluent according to claim 4, wherein the dust is supplied from the high-temperature frame into the molten reducing slag in the ladle and is melted into the oxidized slag. 6. The method for treating steelmaking effluent according to claim 4, wherein the weight ratio of the dust supplied to the molten reducing slag is dust: reducing slag = 1: 0 to 1: 3.