JP3277968B2 - Treatment of steelmaking emissions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to dusts that are discharged during steel making and have been discarded because they have little use value, and that dusts that have been discharged during steel making and have little use value have been discarded. The present invention relates to a method for treating steelmaking effluent that is suitable for effectively utilizing existing reduced 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 steelmaking work using such an electric furnace, the furnace capacity is increased and the electric power (UHP) is increased. , Water cooling box, degassing method (D
(H method, RH method), ladle refining, introduction of DC furnace, etc.

[0003] In steel making operations using such electric furnaces and the like, dust collectors of a direct type or a building type are installed in order to prevent air pollution. Is discharged.

[0004] Similarly, in a steel making operation using such an electric furnace or the like, the inserted steel scraps and the like are:
Steel is produced through a melting stage, an oxidation stage, a slag removal process, and a reduction stage. During this time, oxidized slag and reduced slag, which are steelmaking emissions, are also discharged.

[0005]

Among such steelmaking emissions, dust has a high ZnO content (for example, about 1%).
(0 to 25% by weight), but it is hardly reused.

[0006] This dust is converted to Fe oxide as F oxide.
e content is high (for example, about 50 to 60% by weight as FeO or Fe ₂ O ₃ ), and although this Fe oxide cannot be reduced to be recovered as Fe, it is economical. The fact is that it is not.

On the other hand, oxidized slag is reused, for example, as a roadbed material for asphalt-paved roads. However, reduced slag has a large CaO content in its components, and this CaO reacts with moisture to produce CaO (lime). ) + H ₂ O (water) → Ca
Since the volume expands about twice by changing to (OH) ₂ (slaked lime), when this reduced slag is used as a roadbed material as it is, the reaction with rainwater and the like progresses as the days pass. It is not preferable because it expands and lifts the asphalt pavement surface.

[0008] Therefore, when the reduced slag is used as a roadbed material, the volume is expanded by performing a so-called aging treatment of exposing it to rainwater, immersing it in a reservoir, or bringing it into contact with steam for a long period of time on a factory site or the like. there must be changed to the Ca (OH) _2, the aging operation was not or require long days, much preferred by or require a large site for accumulating.

[0009]

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

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for treating a steelmaking effluent, wherein powder dust, which is a steelmaking effluent, and reduced slag, which is also a steelmaking effluent, are disposed downward at an upper portion of a processing vessel. It is characterized in that it is configured to be supplied to the high-temperature flame of the burner and sequentially melted into the oxidized slag, and in the embodiment, the dust and the reduced slag are supplied to the high-temperature flame of the oxygen burner to be supplied to the oxidized slag. It is possible to melt the slag or supply the dust and the reduced slag in a weight ratio of dust: reduced slag = 1: 1 to 1: 3
It is characterized by having made it.

Further, when a relatively large amount of ZnO is contained in the dust, the amount of ZO contained in the dust is large.
Since almost half of nO is transferred into exhaust gas, high ZnO
A concentration of secondary dust is obtained. Therefore, this ZnO can be recovered and used as a Zn raw material.

[0012]

According to the method for treating steelmaking effluent according to the present invention, the powder dust and the reduced slag supplied into the high-temperature frame are melted and mixed with each other, so that CaO is reduced. Oxidized slag with small volume expansion is obtained, and this oxidized slag can be used as a roadbed material of asphalt-paved road without aging treatment. Dust that had been treated as
Similarly, both of the reduced slag, which is also a steelmaking waste and which has been treated as industrial waste, can be effectively used, and when the secondary dust contains a relatively large amount of ZnO, a high ZnO content is obtained. By being recovered as dust, it can be effectively used as a Zn raw material.

[0013]

FIG. 1 shows an embodiment of a method for treating steelmaking effluent according to the present invention, in which a processing vessel 2 is mounted on a table 1 and a gutter 3 of the processing vessel 2 is provided. A slag pan (or water tank) 4 is provided below the slag pan.

Further, a lid 2a is placed over the processing vessel 2, and an oxygen burner (pure oxygen burner in this embodiment) 5 that penetrates the lid 2a is arranged. The fuel 7 is supplied through a pipe 6 and oxygen (primary oxygen 1) is supplied through pipes 8 and 9 respectively.
0a, secondary oxygen 10b) 10 is supplied, and when the fuel 7 is burned by the oxygen 10, the high-temperature flame 11 comes out from the tip of the oxygen burner 5.

The oxygen burner 5 has a pipe 12 (1
2a), powder dust 14 in the dust hopper 13 is supplied. At this time, the supply of the dust 14 is carried by a carrier gas (air in this embodiment) 16 fed from a pipe 15. This is done by the flow of.

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

Further, inside the oxygen burner 5,
In order to cool the jacket of the oxygen burner 5, a cooling water 22 flows through a pipe 21.

FIG. 2 is an explanatory bottom view showing the tip portion of the oxygen burner 5, and shows a central hole 5a formed in the center.
The fuel 7 which has been pressurized and atomized is supplied, the primary oxygen 10 (10a) is supplied from a ring-shaped slit 5b formed outside the center hole 5a, and a large number of outermost round holes are formed. Secondary oxygen 10 (10b) is supplied from 5c.

A plurality of elliptical elongated holes 5d formed between the slit 5b and the round hole 5c allow the carrier gas 1
Powdered dust 14 and reduced slag 1 together with 6, 20
8 are supplied. Although not shown in FIG. 2, as described above, a water cooling structure in which the cooling water 22 flows outside 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 reduction slag 18 does not need to be a specific position, and the hole for supplying the powder is formed on the outermost side of the oxygen burner 5. If the fuel 7 is a gas, there is no need to spray the fuel 7. Therefore, a hole for supplying powder is formed at the most central portion, and the fuel 7 and oxygen 10 (10a, 10a, 10b) may be provided.

Each of the dust hopper 13 and the slag hopper 17 is provided with a valve or a rotary feeder 13a, 17a capable of controlling a flow rate, so that the supply amounts of the dust 14 and the reduction slag 18 can be adjusted. Is available.

Further, a slag pan (or water tank)
A dust collection duct 27 for collecting the exhaust gas 26 discharged together with the molten slag 25 from the gutter 3 is installed above the gutter 3, and the high dust Z in the secondary dust is passed through the dust collection duct 27.
The nO dust is collected.

In the steelmaking waste treatment equipment shown in FIG. 1, the fuel 7 was burned with oxygen 10 to generate a 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)
Is the theoretical amount of oxygen required for complete burning of kerosene (ie, an oxygen ratio of 1.0).

The amount of air serving as the carrier gas 16, 20 was an amount of air containing 5% of the theoretical amount of oxygen required for complete combustion of kerosene.

Therefore, the high-temperature frame 11 at this time is
The ratio of oxygen to kerosene in the medium is 1.05, which indicates that the oxygen is slightly excessive.

In such a state, the steelmaking discharge, Table 1
The main component dust 14 shown in FIG. 1 and the main component reduced slag 18 also shown in Table 1 which is the steelmaking discharge are supplied to the valve or the rotary feeder so that the two kinds of supply ratio are 1: 1 and 1: 3. The opening degree or rotation speed of 13a, 17a and the flow rate of carrier gas 16, 20 are adjusted and supplied into high-temperature frame 11;
Melt and mix the powder dust 14 and the reduced slag 18 with
By flowing into the slag pan 4 through the bottom of the vessel 2 and the gutter 3, it was recovered as oxidized slag 29 of the main component shown in Table 2. When a water tank was used instead of the slag pan 4, it was possible to obtain granular oxidized slag by the surface tension of the glassy fluid.

The ZnO concentration in the secondary dust collected through the dust collection duct 27 at this time was as shown in Table 2.

[0029]

[Table 1]

[0030]

[Table 2]

The thus obtained oxidized slag having a small amount of CaO and a small volume expansion can be used as a base material for asphalt-paved roads or the like by aging as it is or by a lighter aging treatment than conventional reduced slag. The high ZnO secondary dust was reusable as a Zn source.

As a comparative example to the present invention, an example 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 suppressed to 95% or less of the theoretical amount of oxygen required for complete combustion of the fuel 7.

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

This CO gas is supplied to the Z
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, which is oxidized again in the dust collection duct 27, thereby increasing the ZnO concentration in the secondary dust. Is seen. This tendency is an advantageous method for recovering ZnO.

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

However, in this case, since the combustion is not complete, the temperature of the high-temperature flame 11 and the calorific value in the high-temperature flame 11 decrease, resulting in the use of a large amount of fuel, and an economical method for obtaining oxidized slag. Was disadvantageous.

[0039]

According to the method for treating a steelmaking effluent according to the present invention, the powder dust as the steelmaking effluent and the reduction slag as the steelmaking effluent are disposed downward at the upper part of the processing vessel. Since it was configured to be supplied into the high-temperature frame of the burner and sequentially melted into oxidized slag, this oxidized slag has a small amount of CaO and a small volume expansion.
Because it can be used as a roadbed material for asphalt paved roads, it is a remarkable advantage that dust, which is regarded as industrial waste, and reduced slag, which is also regarded as industrial waste, can be effectively used. The effect is brought about.

[Brief description of the drawings]

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

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

[Explanation of symbols]

 Reference Signs List 5 oxygen burner 7 fuel 10 oxygen 11 high temperature flame 14 dust 18 reduced slag 29 oxidized slag

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-65552 (JP, A) JP-A-60-26284 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 5/00-5/06 C22B 7/02-7/04

Claims (3)

(57) [Claims] 1. Powder dust as a steelmaking discharge and reduced slag also as a steelmaking discharge are supplied into a high-temperature frame of a burner disposed downward at the upper part of a processing vessel, and are sequentially dissolved in the oxide slag. A method for treating steelmaking effluent, comprising: 2. The method for treating steelmaking effluent according to claim 1, wherein the dust and the reduced slag are fed into a high-temperature flame of an oxygen burner and are melted into oxidized slag. 3. The method for treating steelmaking effluent according to claim 1, wherein the supply ratio of the dust and the reduced slag is in a weight ratio of dust: reduced slag = 1: 1 to 1: 3.