JP3048601B2 - Treatment method for metal-containing dust and sludge by-produced in steel works - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for treating dust and / or sludge generated in an iron making process containing a metal and a metal oxide in an ironworks.

<Prior Art> For example, dust collected in a converter contains metallic iron (hereinafter, M.Fe) in an amount of 20% or more, and further contains iron (hereinafter, FemOn) in an amount of 30% or more. Conventionally, converter dust is collected by a wet or dry dust collection method, but in the wet method, it is dehydrated and then dried to form a cake, and in the dry method, it is reused as a powder. Have been. Further, the above-mentioned dust is generally formed into pellets or briquettes in order to be used as a raw material for sintering or other steel or steel. As a method of pelletizing these dusts, (A) JP-A-49-79
Hydrous sludge (slurry) containing FemOn as in Japanese Patent No. 964
A method of contacting and stirring oil and alkali containing animal and vegetable oils, and (b) oxides, hydroxides, carbonates, and sulfuric acids of barium on fine ores as disclosed in JP-A-56-105438. 0.1 to 10.0% of salt converted to one or more BaO values
Distributing the mixture, further mixing a cement binder, agglomerating the mixture, curing the mixture, and producing a product by uncuring. (C) Japanese Patent Application Laid-Open No. 56-56298
As in the publication, quicklime and / or cement is added to dust containing moisture, and the moisture content of mini-pellets immediately after production is 110 ° C.
× added for 10 to 20% after drying for 24 hours,
A method for producing mini-pellets characterized by stirring and mixing at high speed is disclosed. (D) JP-A-53-13
No. 5815 discloses that 0.
There has been proposed a method for producing pellets, which comprises mixing and granulating 2 to 5% by weight of digested dolomite as a binder.

<Problems to be Solved by the Invention> The conventional method described above increases the cold crushing strength of the raw pellets,
This is a useful method to prevent crushing and pulverization during transportation and in the recycling process.However, when it is reused as iron and steelmaking raw materials, it requires auxiliary raw materials for agglomeration of dust and reduces dust recycling costs. In terms of cost.

In addition, when the dust is used as it is, the utilization rate of the iron component having a low degree of oxidation such as metallic iron and FeO is low, and for example, when reused in a converter, extra Fe ₃ O ₄ , Fe ₂ O ₃ Requires heat energy.

Japanese Patent Application Laid-Open No. 49-109212 discloses that the temperature of a heated gas when drying unburned dust collected by water spraying with a dryer in collecting gas from a converter is set to 900 ° C. or less, and the dried dust is dried. oxidation processing method of the converter unburned dust, characterized in that changing the most regulations and dust in Fe a moisture content of 5-10% to the Fe ₃ O ₄ at the time of discharge,
Has been proposed. However, in this method, (a)
Extra heat energy is required for the reduction of Fe ₃ O _{4 in} the recycling process. (B) Extra heat energy is required for the oxidation treatment. (C) When added to an iron bath such as a converter, the local heat absorption due to the reduction of Fe ₃ O ₄ causes a disadvantage that the iron oxide content in the slag is increased more than necessary.

The present invention solves the problems of the conventional method as described above, and reduces iron oxide dust and steelmaking dust or iron oxide iron sludge metal iron and / or FeO, and also valuable metal oxides such as NiO, Cr ₂ O ₃ and MnO. The present invention has been made to provide a method for economically and reliably producing a lump and granular material by reducing and sintering a powder raw material containing a product or a dewatered cake.

<Means for Solving the Problems> The present invention provides a non-oxidizing material having an oxygen concentration of 5% or less without powdering metal-containing dust and sludge and / or dewatered cake as by-products of an ironworks without pelletizing. Ironmaking characterized by being used as a raw material for ironmaking and steelmaking after heating to a temperature exceeding at least 900 ° C. in a reducing gas atmosphere containing carbon monoxide gas and hydrogen gas to form a reduced sintered mass. It is a method of treating by-product metal-containing dust and sludge by-produced by using a powdery substance and / or dewatered cake previously dried at 200 ° C. or lower, as described in the preceding item, In addition, the metallurgical dust in iron and steelmaking exhaust gas is collected by a dry dust collection method using powdery material, and the metallurgical dust as a by-product of the preceding item is used.
The method for treating sludge, and the method for treating metal-containing dust and sludge as a by-product of the ironworks described in the preceding paragraph using the dewatered cake of steel pickling effluent sludge, and blast furnace gas and converter gas as reducing gas , And at least one of coke oven gases is used to treat metal-containing dust and sludge as a by-product of an ironworks.

<Operation> In the present invention, as shown in FIG. 3, at a temperature of 900 ° C. or more, 50% of metallic iron / total iron × 100 (%) contains an oxygen concentration of 5% or less or contains CO and H ₂ . Since the heating is performed in a reducing gas (oxygen concentration: 0%), the condition is satisfied that the oxidation reaction by oxygen in the atmosphere is slight or completely absent.

Also, since the temperature was raised to 900 ° C or higher,
As shown in FIG. 4, when heating is performed in an atmosphere of N ₂ gas at a flow rate of 1 Nm ³ / min, the reduction reaction of metal oxide by carbon in dust proceeds, and CO gas reaches as much as 45%. From around 900 ° C, the sintering reaction of metallic iron progresses, and the adhesion and sintering of dust particles progresses, thereby improving the cold drop strength as shown in Fig. 5 and mounting the shaft from the furnace top to the shaft. The drop strength of the raw material required for charging and charging from the on-furnace bunker to the converter is obtained.
As a guide, the drop strength is 50% or more when put into a converter, and 85% or more when charged into a shaft furnace, each achieved at a heating temperature of 900 ° C and 1100 ° C. Is done.

The drop strength was measured using JIS M 8711
The following method along with was used.

That is, about 20 kg of a 10 to 50 mm sample is placed in a sample box with a door at the bottom, and the sample box is dropped on an iron table
Raise to 2m height, quickly open the sample box door and drop the sample at once. The entire amount of the sample dropped on the iron table is placed in the sample box and raised to a height of 2 m.

Repeat the dropping operation four times in this way, and reduce the total amount of the sample to 10 mm.
Weigh the sample on the sieve with a sieve.
The drop strength is calculated by the following equation.

 Drop strength = A / B x 100 where A: amount of sample 10mm or more after sieving, B: amount of sample before test.

The difference between dehydrated cake and dry dust is low (about 100
C.), the time required for the dehydrated cake was only long due to evaporation of water, and there was no difference in the final properties after heating above 900 ° C. When using dry dust, there is almost no increase in the amount of oxidation when dried at 200 ° C. or less.

As the reducing gas, by-product gas from steel works is also suitable in terms of composition, and can be used as an inexpensive gas. But 90
In the temperature range of 0 ° C. or higher, the deoxidation reaction by carbon usually contained in the dust in the amount of about 4% is mainly performed. Therefore, the reducing gas only needs to achieve the effect of suppressing the atmospheric oxygen concentration to a low level.
Only a small amount is needed.

Since the pickling effluent sludge contains a large amount of iron oxide, the same treatment as that of the dust can be performed. Since the pickling effluent sludge has a carbon concentration of 1% or less, which is lower than that of dust, it is preferable to use the sludge mixed with dust. Sintering can be performed with about 1% of carbon, but in some cases, it is also effective to add fine coal which is collected when handling coal at an ironworks. In addition, coke powder may be used, but inexpensive coal dust powder is preferable.

<Example> Fig. 1 shows an example of a 50 kg / H class reduction sintering test furnace.

The dehydrated cake sludge or the dried dust powder is received by the inlet hopper 1 and the SUS 30 is moved inside the furnace.
(4) A 40 mm thick and 0.5 m wide layer is charged via a feeder 2 on a 0.8 mm t endless belt 4 made of stainless steel. The running speed of the endless belt 4 is 200 mm / min, and the cake is dried and heated to 800 ° C. in the pre-tropical zone 6 and enters the heating zone 7. In the heating zone 7, the temperature is raised to a predetermined temperature of 900 to 1100 ° C. to perform reduction sintering. Atmosphere gas was supplied into the furnace at 1 Nm ³ / min in this test using N ₂ or C (coke oven gas). Dust dewatering cake, dried dust, pickling effluent sludge dewatering cake, dust dewatering cake and pickling sludge dewatering cake
Each 50% mixture was subjected to a reduction sintering test. Table 1 shows the results.

As described above, for all raw materials, the temperature of the heating zone
At 900 ° C, the required drop strength of 50% or more for converter input is satisfied, and at 1100 ° C, the required drop strength of 85% or more for charging a blast furnace (shaft furnace) is satisfied.

Also, the reduction rate is more than 60% and most is more than 80%,
The required heat source in the recycling facility can be greatly reduced.

Further, it was also found that the proportion of metallic iron in the total iron was almost all T.Fe except metallic pickling sludge.

In the above embodiment, a reduction sintering furnace using an endless belt was used. However, as shown in FIG. 2, a sintering case 10 which is a small container similar to a mold of a cast iron machine is endlessly connected in a caterpillar manner. A transported body may be used.

<Results of the Invention> The present invention can prevent the oxidation of metal-containing iron dust and sludge by reducing the oxygen concentration in the atmosphere to 5% or less or a reducing gas. Since reduction sintering can be performed with carbon and a drop strength of 50% or more can be secured, it can be supplied at low cost to a reuse process such as a converter without the need for a heat source again.

Since it can be applied to dry dust, pickling sludge, and dewatered cake, the collection and reuse rate of metal-containing dust and sludge at steelworks has been improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a test belt furnace for reduction sintering, and FIG.
The figure is a perspective view showing another example of the carrier of the reduction sintering furnace, and FIG. 3 is a characteristic diagram showing the relationship between the oxygen concentration in the atmosphere and the ratio of the total metal in iron after heating to 950 ° C. FIG. 4 is a characteristic diagram showing the relationship between the heating temperature and the CO concentration in the atmosphere when the atmosphere gas is N ₂ (flow rate 1 Nm ³ / min), and FIG. 5 is a diagram showing the heating temperature and the drop of the reduced sintered body. FIG. 4 is a characteristic diagram showing a relationship with strength. DESCRIPTION OF SYMBOLS 1 ... Dust receiving hopper, 2 ... Feeder, 3 ... Drive roll, 4 ... Endless belt, 5 ... Heating source, 6 ... Pre-tropical, 7 ... Heating zone, 8 ... Cooling room, 9 ... ... reduction sintering furnace, 10 ... sintering case, 11 ... sintering case connection.

Continuation of the front page (56) References JP-A-49-10109 (JP, A) JP-A-51-28516 (JP, A) JP-B-37-7856 (JP, B2) (58) Fields investigated (Int .Cl. ⁷ , DB name) C22B 1/16 C22B 7/02

Claims (5)

(57) [Claims] 1. A powdery substance and / or dewatered cake of metal-containing dust and sludge as a by-product of an ironworks, without pelletizing, in a non-oxidizing atmosphere having an oxygen concentration of 5% or less, or a carbon monoxide gas, In a reducing gas atmosphere containing hydrogen gas, after heating to a temperature exceeding at least 900 ° C. to form a reduced sintered mass, it is used as a raw material for steelmaking and coppermaking. How to treat sludge. 2. A powdery substance previously dried at a temperature of 200 ° C. or lower and / or
2. The method for treating metal-containing dust and sludge as a by-product of claim 1, wherein a dewatered cake is used. 3. The method for treating by-product metallurgical dust and sludge as claimed in claim 1, wherein a powdery material obtained by collecting metal-containing dust in iron and steelmaking exhaust gas by a dry dust collection method is used. 4. The method for treating metal-containing dust and sludge as a by-product of an ironworks according to claim 1 or 2, wherein a dewatered cake of the pickling effluent sludge of steel is used. 5. A blast furnace gas as a reducing gas, a converter gas,
Claim 1, wherein at least one kind of coke oven gas is used.
The method for treating metal-containing dust and sludge as a by-product of an ironworks according to 2, 3, or 4.