JP2001181745A - METHOD FOR PRODUCING IRON ORE AGGLOMERATE USING WASTE SOLUTION AFTER WATER IMMERSING TREATMENT OF Na- CONTAINING SLAG - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an iron ore agglomerate enabling the inexpensive treatment of a large quantity of Na-containing waste solution generated by water immersing treatment and water vapor aging treatment of Na-containing slag and also capable of attaining the improvement of the yield of a product agglomerate and the increase of the production. SOLUTION: When adding a blending water to pulverized iron ore, conducting granulation, successively conducting each treatment of drying, water removing and preheating and moreover conducting firing to form into a fired pellet, as the blending water, a waste solution after the water immersing treatment and/or water vapor aging treatment of Na-containing slag is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention uses a waste liquid such as a water immersion treatment generated when a steel slag containing Na (hereinafter referred to as "Na-containing slag") is rendered harmless by a water immersion treatment or the like. And a method for producing iron ore pellets or sintered ore.

[0002]

2. Description of the Related Art Conventionally, when desulfurizing and dephosphorizing hot metal, a lime-based desulfurizing and dephosphorizing agent (CaO, CaC ₂ , CaF _{2) is} mainly used.
Among them, CaF ₂ has been widely used because it has a function of lowering the viscosity of slag to improve fluidity and promoting a desulfurization / dephosphorization rate. However, the use of CaF ₂ has been restricted due to the tightening of environmental regulations in recent years, and the switch to soda ash (Na ₂ CO ₃ ) having the same effect has been progressing. However, since the slag after the treatment with soda ash contains Na at a high concentration, as follows:
Applications and usage are limited.

[0003] For example, when used for cement, which is one of the main uses of conventional steelmaking slag, the allowable amount of alkali for cement is determined. The reason that this allowance is determined is that when mixing cement and aggregate to make concrete, the aggregate reacts with alkali, the so-called alkali-aggregate reaction, which causes cracking due to expansion of the concrete. This is to prevent that. Therefore, the amount of slag with a high Na content is limited for use in cement.

In addition, when steelmaking slag having a high Na content is used for roadbed materials, there is a problem that Na is easily eluted when it comes into contact with rainwater or the like, so that it cannot be used.

[0005] Utilizing the property that Na is easily eluted in water,
There are many conventional techniques for recovering and reusing Na from slag generated when performing hot metal pretreatment with soda ash. For example, there are many techniques for dissolving Na with water from slag after hot metal pretreatment using soda ash, and recovering sodium carbonate generated by contact with CO ₂ gas.

Further, Na is removed by adjusting the conditions of pulverization and sizing, steam aging and water immersion according to the basicity of the slag and the Na content. Na that can be used for roadbed materials
There has been proposed a method for producing a slag with little elution of slag (JP-A-09-052740).

On the other hand, one of the inventors of the present invention is to use a Na compound (sodium silicate, sodium phosphate, etc.) in the step of granulating iron ore pellets, which is a raw material of a blast furnace (blast furnace) for producing pig iron, and the step of pseudo-granulating sinter. Is added, so that a low melting point akumite compound or Na ₂ O—P ₂ O ₅ —Fe ₂
By forming O ₃ -based compounds and the like to increase the bonding force between iron ore powders and increase the strength of iron ore pellets and sintered ore, the yield of iron ore pellets and sintered ore can be improved and the production amount can be increased. A method for producing iron ore agglomerate was proposed (Japanese Patent Application No. 10-254024, Japanese Patent Application No. 11-141669).
issue).

Further, one of the inventors of the present invention has proposed that Na is contained as the above Na compound by utilizing an alkaline waste liquid generated in the bleaching process of paper pulp or a sodium silicate waste liquid used for degreasing rolled steel sheets. Of iron ore agglomerate ore capable of treating wastewater to be treated is proposed (Japanese Patent Application No. Hei.
No. 260027).

[0009]

When the hot metal pretreatment with soda ash is carried out under a condition where a large amount of slag is present, the loss due to the evaporation of soda ash is small, and the desulfurization and dephosphorization efficiency are high. It is often carried out after desulfurization and dephosphorization of the system. Therefore, the Na concentration (converted) in the slag after the hot metal pretreatment is about 0.7 to 11% by mass, and the method of recovering sodium carbonate from the slag is a method of recovering sodium carbonate because of the large amount of slag processed. Due to the small volume, it is not economical and has not been implemented.

In the method disclosed in Japanese Patent Application Laid-Open No. 09-052740, the treatment of a waste liquid containing eluted Na after steam aging and water immersion treatment is usually expensive in waste water treatment equipment such as a thickener. Since the water can be discharged only after neutralization treatment using an alkaline neutralizing agent or the like, there is still a problem in economy.

Therefore, at present, the amount of slag containing a high concentration of Na is limited, and most of the slag is landfilled as industrial waste. However, the cost of waste disposal has been rising due to the tightening of environmental regulations in recent years, and the development of effective utilization methods has been desired.

On the other hand, the inventions disclosed in Japanese Patent Application Nos. 10-254024 and 11-141669 require a chemical such as sodium silicate. In addition, Japanese Patent Application No. 11-26
The invention disclosed in the specification No. 0027 and the like does not require expensive chemicals and can use a waste liquid, so that the above problem can be solved.However, in the case of using a pulp waste liquid, a waste liquid from a paper mill to a steel mill is used. Transport and transportation costs are a problem.On the other hand, when degreasing wastewater from rolled steel sheets is used, transportation and transportation costs are not a problem because they can be procured in a steel mill. The amount is overwhelmingly small, the mixing ratio is limited to a low level, and there is a problem that the effects of improving the yield of the agglomerate ore and increasing the production amount cannot be sufficiently obtained.

Accordingly, an object of the present invention is to inexpensively detoxify a large amount of Na-containing waste liquid eluted by immersing and / or steam aging Na-containing slag such as pre-treated hot metal slag using soda ash. It is an object of the present invention to provide an economical treatment method which can be carried out and has no problem of transportation cost.

[0014]

Means for Solving the Problems The inventors of the present invention have developed a waste liquid containing Na eluted after a water immersion treatment of Na-containing slag and / or steam aging (hereinafter referred to as "Na-containing waste liquid").
Is considered to be able to solve the above-mentioned problems by using
The present invention has been completed.

That is, in the present invention, the invention according to claim 1 is characterized in that the compounded water is added to the fine iron ore to perform granulation, followed by drying, water separation and preheating, followed by further calcination. When producing fired pellets, Na is used as the compounding water.
It is characterized by using a waste liquid obtained by subjecting the contained slag to a water immersion treatment and / or a steam aging treatment.

In a slag containing Na such as a slag of hot metal pretreatment using soda ash, Na is sodium silicate,
It exists in the form of a compound such as sodium phosphate.
Since these sodium compounds are water-soluble, they are easily eluted from the slag by immersing the slag in water or placing it under an atmosphere of steam. Further, although free CaO exists in the Na-containing slag, it reacts with water or steam to be stabilized to Ca (OH) ₂ . Therefore, even if the slag subjected to the water immersion treatment or the steam aging treatment is used for the roadbed material or the like, the elution of Na no longer poses a problem, and free CaO reacts with atmospheric moisture and CO ₂ to cause Ca (OH). The problem of slag expansion due to the production of ₂ and CaCO ₃ is also eliminated.

The waste liquid collected after the water immersion treatment or the steam aging treatment contains sodium compounds such as sodium silicate and sodium phosphate eluted from the slag. In the pellets (raw pellets) granulated using the waste liquid containing these sodium compounds as blending water, only moisture is removed at a gas temperature of 180 to 250 ° C. in the drying step, and the sodium compounds remain in the pellets. In the next water separation treatment step, 1 to 3% by mass of crystal water in the fine iron ore is removed at 250 to 400 ° C., but at such a low temperature, the remaining sodium compound hardly changes.

In the next pre-heat treatment step,
Sodium compounds remaining in the pellets due to heating
Is Fe, the main component of iron ore_TwoO_ThreeIn iron and iron ores
Min of SiO_TwoReacts with the akumite compound (Na_TwoO ・
Fe_TwoO_Three・ 4SiO_Two), 5Na_TwoO ・ Fe_TwoO_Three・
8SiO_Two, 9NaPO_Three・ Fe_TwoO_Three, 3NaPO _Three
・ Fe_TwoO_ThreeTo form a low melting point compound
The compound forms a liquid phase at the point of contact between the iron ore powder and liquid phase sintering occurs.
This combines iron ore powder with each other. Furthermore, this liquid phase sintering
The low melting point compound in the liquid phase and the iron ore Fe_Two
O_ThreeThe reaction by mutual diffusion with
High melting point compound, liquid phase disappears and liquid phase sintering is completed
You. In addition, the melting temperature of the akumite compound is 1000 ° C or less.
Wide composition range with dots, low melting point composition of 760 ° C
Can be The strength of the preheated pellets by liquid phase sintering is
Significant improvement compared to preheated pellets with solid phase sintering alone
(Koichi Morioka et al .: CAMP-ISIJ, V
ol. 11 (1998) p. 914).

Therefore, the yield can be improved by increasing the strength of the preheated pellets or product pellets, or the production amount of the product pellets can be increased by maintaining the strength of the preheated pellets or product pellets at the same level as usual.

As described above, in the Na-containing waste liquid used as the compounding water used in the granulation treatment step, water evaporates to steam in the treatment step from drying to firing.
Released into the atmosphere together with the exhaust gas from the fired pellet manufacturing process.

On the other hand, the sodium compound is charged into the blast furnace while remaining in the fired pellets as a high melting point compound produced by reacting with Fe ₂ O ₃ . In the blast furnace, Fe ₂
The O ₃ component is reduced to metallic iron, melts and separates into metallic iron and a sodium compound. Since the separated molten sodium compound is diluted into a large amount of slag generated from gangue components of iron ore and ash of coke, the increase in Na concentration in blast furnace slag is up to about 0.05%, which is almost a problem. No. Therefore, the slag is cooled and solidified after being discharged from the blast furnace, and can be effectively used for roadbed materials and the like.

As described above, a large amount of Na-containing effluent generated by immersion of Na-containing slag in water can be processed at a low cost without the need for expensive pretreatment such as neutralization.
It also contributes to an improvement in the yield and production volume of fired pellets.

According to a second aspect of the present invention, mixed water is added to iron ore powder, auxiliary raw materials (limestone, quicklime, quartzite, serpentine, etc.) and solid fuels such as coke powder and coal powder, and the mixture is kneaded by mixing and kneading. In producing a sintered ore by sintering the granulated mixed raw material, a waste liquid obtained by subjecting a Na-containing slag to a water immersion treatment and / or a steam aging treatment is used as the compounding water. It is.

The iron ore powder is usually 4 to 6% by mass.
(External number) is used while having the attached moisture, and the total of the attached moisture and the above-mentioned compounding water is referred to as mixed raw material moisture.

By adding and kneading the waste liquid as the compounding water, the viscosity of the compounding water decreases due to the effect of the sodium compound contained in the waste liquid. As a result, the mixing of the iron ore powder and the auxiliary material can be made more uniform, and the compounding water containing the sodium compound can also be substantially uniformly infiltrated on the surfaces of the iron ore powder and the auxiliary material. Further, the infiltrated compounding water also diffuses into the attached moisture of the iron ore powder, so that the concentration of the sodium compound on the surface of the iron ore powder can be increased.

The mixed raw material quasi-granulated by the kneading is filled on a pallet of a sintering machine (for example, a Dwyroid type sintering machine), and the solid fuel in the mixed raw material on the surface layer is ignited. After ignition, in the process of burning the solid fuel while sucking air downward and sintering the mixed material filled by this combustion heat to form a sintered cake, after drying the mixed material,
By heating to 1150 to 1200 ° C., a melt is generated by a slag reaction between the iron ore in the mixed raw material and the auxiliary raw material. The liquid ore sintering of the iron ore powder is performed by the melt, and after cooling, the required strength of the sintered ore is obtained by bonding of the iron ore powder with the melt.

At this time, as described above, the iron ore powder and the auxiliary material are more uniformly mixed at the mixing stage, and after the moisture is removed by drying the mixed material, the sodium compound is also mixed with the iron ore and the auxiliary material. Because it is almost uniformly dispersed on the surface, the formation of a melt is promoted by forming a low-melting point compound such as the above-described akumite compound, and the generation of the melt is uniform over the entire sintered cake, and the The amount of generation can be increased.

That is, since the akumite compound has a wide composition range having a melting point of 900 ° C. or lower (see Koichi Morioka et al .: CAMP-ISIJ, Vol. 11 (199)).
8) p. 914), the normal sintering temperature of sinter (11
(From 50 to 1200 ° C.). The generated melt promotes the generation of the melt by the slag reaction between the iron ore powder and the auxiliary material, thereby generating a sufficient amount of the melt for sintering the iron ore powder and improving the strength of the sintered ore. Can be.

Therefore, the yield of the product sintered ore can be improved, or the production amount can be increased if the strength of the sintered ore is maintained at the same level as usual.

As described above, in the waste liquid used as the compounding water used in the quasi-granulation step, water evaporates to steam in the sintering step, and together with the exhaust gas from the sinter ore production process. Released to the atmosphere.

On the other hand, the sodium compound is charged into the blast furnace while remaining in the sinter as a slag reaction product, and is diluted in the slag through the same reaction as described in the first aspect of the present invention. Is effectively used for roadbed materials.

Therefore, a large amount of Na-containing waste liquid generated by the water immersion treatment of the Na-containing slag can be inexpensively processed without the need for expensive pretreatment such as neutralization, and at the same time, the product sintered sinter can be produced. It also contributes to improved yield and increased production.

When the amount of residual sodium in the dried raw pellets or the mixed raw material increases, the reduced powderability of the fired pellets and the sintered ore deteriorates. The amount of residual sodium is 0.1
Although the upper limit is 2% by mass, in the present invention, the amount of residual sodium is about 0.01% by mass at the maximum, and there is no problem at all.

The third aspect of the present invention is the first or second aspect.
In the production method of iron ore agglomerate described in the above, as the mixing water, the molten slag taken out of the blast furnace is allowed to cool until solidified, and the Na-containing slag is placed on the solidified blast furnace slag, Characterized by using a waste liquid obtained by spraying water.

When Na-containing slag is placed on the solidified blast furnace slag and water is sprinkled on the slag, a part of the sprinkled water becomes steam due to the sensible heat of the blast furnace slag at 200 to 500 ° C. The slag undergoes water immersion and steam aging on the blast furnace slag. As described above, the free CaO in the Na-containing slag is reduced to Ca (O
H) Since it is stabilized to ₂ and Na is removed, it can be used as a roadbed material or the like.

Since the blast furnace slag is cooled by the same cooling method as that used in normal blast furnace slow cooling slag production (cooling to solidify, then water spray cooling), the blast furnace slag becomes blast furnace slow cooling slag and can be used as a roadbed material or the like. .

Further, since Na in the Na-containing slag is eluted in the sprinkling waste liquid, this eluted Na-containing waste liquid is recovered and used as a compounding water for granulating raw pellets or for pseudo-granulating sintering raw materials. A high-strength agglomerate ore can be produced by the same reaction mechanism as the invention described in claim 1 or 2 described above.

Therefore, according to the present invention, existing blast furnace slow cooling slag manufacturing equipment can be used, so that new equipment for water immersion treatment and steam aging treatment is not required, and the blast furnace slag sensible heat is effectively used. It also contributes to energy savings for steam and steam production.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to specific examples.

First, a preferred embodiment of the water immersion treatment and / or the steam aging treatment of the Na-containing slag and the recovery of the Na-containing waste liquid will be described.

For the method of immersion treatment or aging treatment of Na-containing slag in water, see, for example,
A method similar to the method disclosed in JP-A-9-052740, that is, slag having a basicity of CaO / SiO ₂ (mass ratio) of less than 1.8 and Na ₂ O in the slag having a basicity of 1.8 or more concentration slag is less than 2 wt% after crushing and sizing, subjected to steam aging process of contacting steam and 24 hours or more, Na ₂ of basicity slag at 1.8 or higher
After crushing and sizing, the slag having an O concentration of 2% by mass or more is preferably subjected to a steam aging treatment in which the slag is brought into contact with steam for 24 hours or more, and then subjected to a treatment of immersion in water for 6 hours or more. This is because free CaO in the slag is stabilized, and Na that is easily eluted from the slag is removed, and the subsequent elution of Na almost disappears, and the slag can be used as a roadbed material or the like.

The order and the processing time of the steam aging treatment and the water immersion treatment are not necessarily limited to the above, and the steam aging treatment may be performed after the water immersion treatment. Can be adjusted as appropriate.

The higher the temperature of the steam used for the steam aging treatment, the higher the reaction rate. However, in consideration of the fact that a large amount of energy for producing steam is required and that the condensation and recovery after the treatment are easy, the temperature is 95%. The temperature is preferably from about to 120 ° C. The reaction rate increases as the temperature of the water used for the water immersion increases, but a large amount of energy is required for heating the water.

The steam aging treatment can be performed, for example, by using steam pipes arranged in parallel and embedded in a gravel layer.

The water immersion treatment can be performed by means such as water sprinkling, immersion in a certain amount of reservoir water, immersion in running water, and the like.

Further, as schematically shown in FIG. 1, a width of about 20 mm for producing slow cooling slag from molten blast furnace slag is used.
m, and the molten slag taken out of the blast furnace was discharged into a dry pit having a length of about 50 m to a layer thickness of 3 to 4 m.
After placing the crushed and sized Na-containing slag on the blast furnace slag at 200 to 500 ° C. which has been allowed to cool and solidify for about 36 hours, while adjusting the amount of water in the range of 0 to 6 m ³ / min. Sprinkle water on Na-containing slag for about 12 to 15 hours
The blast furnace slag is cooled by infiltration of water into the a-containing slag, and then the blast furnace slag is cooled by the permeated water. Perform aging processing. As described above, by using this method, the Na-containing slag becomes N
a is removed and free CaO is stabilized, while the blast furnace slag becomes blast furnace slow cooling slag. Therefore, these two types of slag do not need to be separated, but are crushed and sized together and used for roadbed materials and the like.

The waste liquid after the water immersion treatment or the waste liquid obtained by condensing the water vapor after the water vapor aging treatment is collected and temporarily stored in a storage tank, a pound, or the like, and is transported to the agglomerate ore production process by piping, tank lorry, or the like. I just need. It is more preferable to use a part of the waste liquid from a storage tank, a pound or the like by circulating it in a water immersion treatment step or a steam aging treatment step, and to use the remainder in the agglomerate production step. With this method,
Since the concentration of Na eluted in the waste liquid can be increased,
As will be described later, the effect of improving the strength of the agglomerate ore is increased, and the amount of waste liquid transported to the agglomerate ore production process can be reduced, thereby reducing the transportation cost.

(2) Next, a preferred embodiment of a method for producing fired pellets using this Na-containing waste liquid will be described below.

Iron ore powder (T.Fe: 57 to 69% by mass)
94 to 96 parts and limestone or dolomite 4 as an auxiliary material
And 6 parts by weight of the raw material for pellets having an average particle diameter of 40 to 60 μm mixed with Na-containing waste liquid (Na ⁺ : 0.01 to
(0.1% by mass) The raw pellets obtained by adding 7 to 9 parts and granulating to a diameter of 9.5 to 11 mm with a pan-type pelletizer are charged into a traveling grate so as to have a pellet layer thickness of about 20 to 30 cm.

The great consists of three zones: drying, water separation, and preheating. Drying removes the moisture content of the raw pellets at a gas temperature of 180 to 250 ° C. 3% by mass is removed, and in preheating, heating is performed at 950 to 1100 ° C. to react sodium silicate and the like in the waste liquid with Fe ₂ O ₃ in the iron ore powder to form a low-melting akumite compound and the like. With the residence time of the pellets in the great being 15 to 25 minutes, preheated pellets having a strength higher than a predetermined crushing strength (for example, 10 kg / P) that can withstand rolling in the rotary kiln are manufactured, and the preheated pellets are charged into the rotary kiln. , 1250-1350 ° C,
Baking is performed for 10 to 15 minutes.

As described above, the Na-containing waste liquid can be inexpensively treated without performing a preliminary treatment such as a neutralization treatment, and the yield of fired pellets can be improved and productivity can be increased.

(3) A preferred embodiment of a method for producing a sintered ore using a Na-containing waste liquid is described below.

Iron ore powder of 10 mm or less (T.Fe: 57
~ 68% by mass, attached moisture: about 3-5% by mass (external number)) 8
6 to 90 parts, 23 to 27 parts of sinter-returning, and 10 to 14 parts of limestone or quicklime, 3 to 5 parts of coke powder or anthracite powder as auxiliary raw materials, and the same Na-containing waste liquid (Na ⁺ :
1 to 5 parts by mass (0.01 to 0.1% by mass) to a total water content of 6 to 8 parts to obtain a mixed raw material kneaded with a drum mixer and quasi-granulated.

The mixed raw material is filled into a pallet of a Dwyroid type sintering machine to a thickness of 50 to 80 cm, and the coke powder or the anthracite powder in the mixed raw material on the surface layer is ignited.
After ignition, the coke powder or anthracite powder is burned by sucking air downward for 15 to 25 minutes, and the mixed raw material filled with the combustion heat is sintered to form a sintered cake.

After evaporating water in the process from the ignition to the production of a sintered cake, the water is evaporated to 900 ° C. or higher (up to 1250 to 1300
C.) for 2 to 4 minutes to maintain sodium silicate and the like in the waste liquid and Fe _{2 in the} iron ore powder in the same manner as described above.
O ₃ is reacted to form a low-melting akumite compound.

As described above, the Na-containing waste liquid can be inexpensively treated without performing a preliminary treatment such as a neutralization treatment, and the yield of sinter ore and the productivity can be increased.

[0057]

EXAMPLES In order to confirm the effects of the present invention, the following experiment was conducted using molten iron pre-treated slag as a Na-containing slag.

(Example 1) Elution N from Na-containing slag
Experiment on manufacturing method of fired pellets using waste liquid containing a

As the Na-containing slag, three types of slag of hot metal pretreatment using soda ash having the composition shown in Table 1 were used. Each of these slags was crushed and sized to 5 to 15 mm, and 100 g of the slag was purified at room temperature. By immersing in 1000 ml of water and shaking for 6 hours, the Na ⁺ concentration was 110 mg / l, 230 mg / l, and 560 mg, respectively.
/ L of Na-containing waste liquid was obtained.

Next, a dry powder of Hamazley ore (analyzed value is shown in Table 2) ground to a Blaine index of 2000 cm ² / g was mixed with 1% of each of these Na-containing waste liquids as mixing water.
About 8% by mass (external number) of each type was added to make the particle size 9.5 to 1
1 mm raw pellets were granulated.

As a comparative example, granulation was performed under the same conditions when pure water and an aqueous solution of a sodium metasilicate reagent (JIS No. 3) were used as compounding water.

After the raw pellets are dried at a temperature of 110 ° C. for 180 minutes to remove moisture, the dried pellets are heated in an air atmosphere at 1000 ° C. for 10 minutes to form preheated pellets. After cooling, the crush strength was measured. Table 3 shows the experimental results.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

As shown in Table 3, it was shown as a comparative example.
The crushing strength of preheated pellets when granulated with pure water is 10k
g / P, sodium metasilicate reagent (Na ⁺ concentration 380 m
g / l), the crush strength of the preheated pellets is 2
0 kg / P, whereas N shown as an example of the present invention
strong as preheating pellets granulation to the Na ⁺ concentration increases with a containing waste liquid is high, Na ⁺ concentration 560 mg / l
To 23 kg / P. From these experimental results,
After drying the raw pellets granulated with the Na-containing waste liquid,
It was confirmed that the strength of the preheated pellet could be increased by heating at 0 ° C. for a certain time. This is considered to be an effect of increasing the strength of the preheated pellet by progressing the liquid phase sintering due to the formation of the low-melting-point alumite compound described above.

In addition, even if an expensive sodium metasilicate reagent or the like is used, if the Na ⁺ concentration is the same, Na
It was confirmed that the strength of the preheated pellets could be increased with almost the same effect even when the Na-containing waste liquid after the water immersion treatment from the slag containing slag was used.

(Example 2) Elution N from slag containing Na
Experiment on production method of sintered ore using waste liquid containing a

After mixing -10 mm of iron ore powder, auxiliary material, and coke powder in the mixing ratio shown in Table 4, the Na used in Example 1 was adjusted so that the water content of the mixed material became 7% by mass (external number). The waste liquid, tap water, and sodium metasilicate aqueous solution were each added, and the mixture was pseudo-granulated by a drum mixer. Five kinds of mixed raw materials (Sample Nos. 5 to 7: Examples of the present invention, Samples Nos. 8 and 9: Comparison) Example) was manufactured. In addition,
Table 5 shows the components of the blended iron ore powder used in this example.

[0070]

[Table 4]

[0071]

[Table 5]

A sintering experiment using a sintering pot was performed on the above five types of mixed raw materials. In this sintering experiment, the diameter was 100 m
m, filling the mixed raw material in a sintering pot having a height of 300 mm,
Subsequently, the layer surface was ignited, and sintering was performed while suctioning air at a suction pressure of 3500 Pa. After sintering, the drop strength of the product sinter was measured. In addition, drop strength, after repeating the operation of dropping the product sintered ore at a time from a height of 2 m onto an iron table four times, sieving the entire amount with a 5 mm sieve,
The ratio of 5 mm or more was determined. Table 6 shows the experimental results.
Shown in

[0073]

[Table 6]

From Table 6, it can be seen that, as a comparative example, the test No. In comparison with the results of Experiment No. 9, Experiment No. 9 using the Na-containing waste liquid of the present invention as a compounding water. 6
No. 8 to 8 showed that the drop strength of the product sintered ore was higher, and that the higher the Na ⁺ concentration of the Na-containing waste liquid, the higher the drop strength. It is considered that the strength of the product sintered ore is increased due to the promotion of the liquid phase sintering due to the formation of the above-described low melting point alumite compound.

The aqueous solution of the sodium metasilicate reagent of Comparative Example was used as a blending water. Compared to the result of No. 10,
It was also confirmed that when the Na ⁺ concentration was approximately the same, the same drop strength could be obtained even when the Na-containing waste liquid was used for the compounding water.

In the above examples (Examples 1 and 2), the elution of Na from the slag containing Na was carried out by shaking in water, but the present invention is not limited to this. Sprinkling water continuously from above the slag, circulating the wastewater for sprinkling, immersing the slag in running water, circulating the running water, spraying steam instead of water on the slag surface, and condensing it A waste liquid having the same Na ⁺ concentration can be obtained by a method in which Na is eluted in water, the condensed water is evaporated again, and the water is recycled.

[0077]

As described above, according to the first aspect of the present invention, in the granulation step of the iron ore pellet manufacturing process, the Na-containing slag is used as the mixing water in the water immersion treatment and / or By effectively utilizing the waste liquid subjected to the steam aging treatment, a large amount of the Na-containing waste liquid generated in the water immersion treatment of the Na-containing slag can be processed at a low cost without the need for expensive pretreatment such as neutralization treatment. Further, it is also possible to improve the yield and the production amount of fired product pellets.

According to the second aspect of the present invention, in the pseudo-granulation step of the iron ore sinter production process, N is used as the compounding water.
By effectively utilizing the waste liquid obtained by subjecting a-containing slag to water immersion and / or steam aging, a large amount of Na-containing waste liquid generated in the water-immersion treatment of Na-containing slag can be subjected to expensive pretreatment such as neutralization. It is not necessary and can be processed at low cost, and at the same time, it is possible to improve the yield and the production amount of the product sinter.

According to a third aspect of the present invention, in the middle of the existing process of producing the slowly cooled slag from the molten blast furnace slag, the Na-containing slag is placed on the blast furnace slag and sprinkled with water. Or in addition to the effects of the invention described in 2 above, no equipment for water immersion treatment or steam aging treatment is required, and in the production of steam, blast furnace slag sensible heat can be effectively used and the energy for steam production can be reduced. Things.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method of subjecting a Na-containing slag to a water immersion treatment and a steam treatment on a blast furnace slag.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dry pit 2 Blast furnace slag 3 Na-containing slag 4 Sprinkling pipe 5 Water

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C21C 1/02 C21C 1/02 L 105 105

Claims (3)

[Claims] Claims 1. A fine iron ore is granulated by adding a compounding water thereto.
Subsequently, after performing each of drying, water separation, and preheating treatments, in the method for producing iron ore agglomerate which is further fired to obtain fired pellets, the slag containing Na is subjected to a water immersion treatment and / or A method for producing iron ore agglomerate, comprising using a waste liquid after steam aging treatment. 2. Production of iron ore agglomerate by adding compounding water to iron ore powder, auxiliary raw material and solid fuel powder, kneading and sintering the mixed raw material to form a sinter ore. A method for producing iron ore agglomerate, wherein a waste liquid obtained by subjecting a slag containing Na to a water immersion treatment and / or a steam aging treatment is used as the compounding water. 3. The method for producing iron ore agglomerate according to claim 1 or 2, wherein the molten slag taken out of the blast furnace is allowed to cool as solidified water until solidified, and Na is placed on the solidified blast furnace slag. A method for producing an iron ore agglomerate using a waste liquid obtained by placing a slag containing water and sprinkling water on the slag containing Na.