JPH0816249B2 - Pretreatment method in agglomerated ore production - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the production of agglomerated ore which uses converter slag as a flux as a partial substitute for limestone (or quick lime) in the production of agglomerated ore having excellent properties as an ironmaking blast furnace raw material. It relates to a pretreatment method.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory diagram of steps used in a normal sintering method. Agglomerated ore such as sintered ore, which is a main raw material of a blast furnace, is generally manufactured according to a process as shown in FIG. First, Konako as a flux source to approximately 10mm below the fine ore as a raw material, containing CaO auxiliary raw material powder such limestone dolomite, converter slag, as containing SiO ₂ auxiliary materials and return ores and fuel source, such as silica, serpentinite -Using a mixer, add an appropriate amount of water and mix in the primary and secondary drum mixers-
Granulate.

The pseudo-granulated raw material is filled in a grate type sintering machine, and the carbonaceous material of the surface layer portion thereof is 1100-12.
Ignite at 00 ° C, burn coke while sucking air from below with a blower, sinter the raw material by the heat of combustion, then crush with a crusher and screen with a 4 mm sieve. Then, +4 mm is sent to the blast furnace as a product, and -4
mm is repeated as return ore.

The properties of the agglomerated ore produced in this manner are required to have qualities such as cold strength, reducibility, and reduction powderability. Then, in order to ensure this quality, the operation is performed while adjusting the blending ratio of various auxiliary raw materials and the addition amount of coke powder.

The raw iron ore for agglomeration is a conventional high-quality hematite (hematite) / magnetite (magnetite), which has many problems in maintaining product strength.
The ratio of iron ore containing a large amount of e ₂ O ₃ · H ₂ O) is increasing, and technical development corresponding to this is desired.

On the other hand, about 40% of the production of converter slag was landfilled and discarded until about 1980, but after that,
With the tightening of environmental regulations, the amount of landfill waste has gradually decreased, and the amount has recently become 7 to 18% of the production amount. (Nagai et al .: Resources and materials, 107 (1991) No.2, P140) Effective use of this converter slag has been conducted for a long time mainly for civil engineering, and many studies have been conducted.

For example, Japanese Patent Laid-Open No. 55-79837 discloses a mineral raw material 1 containing 100 parts by weight of molten converter slag and MgCO ₃ such as serpentine or dolomite.
Add ~ 30 parts by weight, melt and slag to 2 to 2.5
There is disclosed a method in which the particle size is adjusted to mm so that it becomes a part of the raw material for producing agglomerated ore.

Further, in JP-A-55-128548, a converter slag is crushed and sized to a particle size of 2 to 10 mm, and 1 to 5% by weight is mixed with a sintering raw material. A method of segregating to the lower layer and operating is disclosed.

However, when using these converter slags, in the agglomerated ore manufacturing process, which is the premise thereof, the SiO2 content and coke ratio in the product are relatively high, and the operating rate is also compared with the current situation. It was under the condition of being low.

Recently, a high quality agglomerated ore is required for stable and highly efficient operation of a blast furnace, and the control criteria such as its cold strength, reducibility and reduced pulverization property are becoming strict. Therefore, unlike conventional agglomerated ores, the SiO ₂ content in the product is 5.5% or less, and the production rate is 1.5 t / m ² / H.
Operations above r are approaching normal operating levels.

Therefore, the air permeability is improved by strengthening the pseudo particles of the raw material, and the efficient combustion method is improved by devising the coke addition method.
There are restrictions on the amount and method of addition of auxiliary materials. Under such operating conditions, when the converter slag is used as a substitute for the flux, a decrease in cold strength is observed, so there is a problem that the operation with reduced productivity is forced in order to maintain quality.

Further, the progress of refining technology in the past 10 years has reduced the amount of lime used in the converter, resulting in a decrease in the slag unit consumption. As a result, Ca in the converter slag
The O content has also decreased, and it is necessary to consider qualitative changes in the converter slag.

As described above, in the agglomerated ore production process under the conditions that the SiO ₂ content in the product is 5.5% or less and the production rate is 1.5 t / m ² / Hr or more, the converter slag is used. It is desired to develop a method for effectively utilizing the.

[0014]

When a large amount of goethite iron ore is used as a raw material for producing agglomerated ores, it is possible to decompose and dehydrate bound water in the goethite iron ore during the sintering process. It is already known that many pores are generated due to the cracks that accompany it and become porous. In such a porous ore, during the sintering process, the gas in the pores is trapped in the melt during the melt formation, and a large amount of coarse air holes are formed, resulting in a decrease in the strength of the product.

[0015] The JP 63-33525 Publication As a countermeasure, yielding CaO-MgO-SiO ₂ KeiTorueki by blending containing MgO-SiO2 material was finely pulverized to limonite ore, the high viscosity containing A method of covering the surface of limonite ore with a MgO-SiO ₂ substance to suppress reduction by CO gas and reducing the amount of FeO produced to ensure product quality is disclosed. In this method, the amount of the MgO-SiO ₂ substance to be mixed with the raw iron ore and the Mg-containing content are
The content of MgO and SiO _{2 in} the O-SiO ₂ substance is not specified at all, and there is a problem in practical application.

In Japanese Patent Laid-Open No. 3-47927, the product quality is also improved by adjusting the mixing ratio of the -1 mm part of the MgO-SiO ₂ auxiliary raw material powder and the solid carbon powder in the iron ore of high goethite quality. A method of securing is disclosed. However, with this method, it is difficult to control the mixing ratio of -1 mm part of each raw material powder on an industrial scale.

In any of the methods, addition of a MgO source mainly composed of serpentine in order to densify the texture of the product leads to an increase in the amount of slag, which is not preferable in the operation of the blast furnace as a post process. It's obvious.

The object of the present invention is to positively utilize the converter slag, which has been more difficult to be dumped than the conventional one, in the agglomerate production process, so that the amount of the goethite ore tends to increase gradually in recent years. It is intended to provide a pretreatment method in the production of agglomerated ores, which enables to use a large amount of

[0019]

The present invention has been made to solve the above problems and achieve the above object.

In the present invention, a part of limestone (or quick lime) as a flux during the production of agglomerated ore is replaced by a converter slag, and the particle size of the converter slag used for the replacement is −
The particle size is 1 mm and -0.125 mm is present in an amount of 30% or more.

The blending amount of the converter slag is set so that the basicity CaO / SiO _{2 of the} entire raw material maintains the basicity value when limestone (or quick lime) is used.

[0022] After adding, mixing, and pseudo-granulating a set amount of converter slag to ores containing the goethite mineral, or mixing them with other raw materials, or making the ores containing the goethite mineral into pseudo-granulate. The pretreatment method in the agglomerated ore production is characterized by coating the surface with converter slag and then blending it with other raw materials.

[0023]

As described above, in the process of assimilation with limestone (or quick lime), the goethite ore becomes a structure mainly composed of a super-melted portion and a coarse air hole portion, which causes various problems including deterioration of product strength. .

The present invention solves the above problems by mixing converter slag, which has a remarkably poor assimilation reactivity with ore, with a goethite ore.

First, the converter slag is crushed to -1 mm, and the slag is -0.
When 125 mm is set to 30% or more, it becomes a powder of pseudo particles when mixed with the raw ore.

The reason why the converter slag is limited as described above is that, as shown in FIG. 1 of the embodiment described later, when the particle size of the converter slag is −0.125 mm of 30% or more, the quality characteristics are This is due to good results, because fine converter slag adheres and mixes around the particles so as to cover the particles of the goethite ore, which reduces the amount of direct reaction between lime and the goethite ore. It is believed that there is.

Furthermore, it is more desirable to add or coat the surface of the raw material ore after it is made into pseudo particles.

Further, the addition amount of the converter slag is adjusted so that the basicity of the whole raw material (CaO
/ SiO ₂ ) is added and mixed as an alternative to lime, whereby an agglomerated ore of a quality suitable for a blast furnace in the subsequent process is obtained.

As already mentioned, the main constituents of the converter slag are high melting point 2CaO.SiO ₂ and 2CaO.Fe ₂
Since it is O ₃ , and the free CaO source is small, the assimilation reactivity is significantly worse than that of limestone (or quick lime) which is usually used as a flux. Therefore, even if the ore becomes a porous form during the sintering process, such as a goethite iron ore, the assimilation reaction does not proceed unless the temperature is raised to around 1300 ° C. by using the converter slag. Therefore, the entire structure of the product becomes the structure of the over-melting part and the coarse air hole part due to the formation of the CaO.Fe ₂ O ₃ -based low melting point melt that occurs in the case of limestone (or quick lime) which is usually used as a flux. Without densification.

That is, at a temperature of 1300 ° C. or higher at which a melt is generated on the surface of the goethitic iron ore, the densification of the goethitic iron ore has already progressed, so there is no concern about assimilation with bubble formation. As a result, the processing can be performed without lowering the strength of the product and the resulting reduction in yield and productivity.

[0031]

EXAMPLE FIG. 2 is a process explanatory view of an embodiment of the present invention in which a converter slag is preliminarily mixed and added to a goethite ore, and FIG. 3 is a book in which the surface of the goethite ore is coated with the converter slag. It is a process explanatory drawing of another embodiment of the invention.

Using the goethite ore and the converter slag having the chemical components shown in Table 1 below, the goethite ore and the converter slag are pretreated in accordance with the process charts shown in FIGS. Granulated, manufactured sinter, and used conventional hematite iron ore according to the process diagram shown in FIG. 4 and the conventional method using only limestone without converter slag and also according to the process diagram shown in FIG. A comparative evaluation of the product by the conventional method and the product was performed.

[0033]

[Table 1]

The pretreatment method according to the method of the present invention was able to improve productivity while ensuring product quality, as compared with the conventional method.

Example 1 First, as shown in FIG. 2, a goethite powder ore of about 10 mm or less and a converter which was previously crushed to -1 mm to have an average particle size of 0.2 mm or less. The slag is drawn out from the ore tank, water is added and mixed in the primary drum mixer, the mixed ore is stored in a cutting hopper, and then, as a flux source, CaO-containing auxiliary raw material powder (limestone etc.) and SiO2 auxiliary raw material are used. Add silica stone, serpentine, etc., adjust and mix so that the basicity is 1.95, further add coke powder as a fuel source and add an appropriate amount of water and mix it in a secondary drum type mixer The product is made into particles, charged into a sintering machine and fired to obtain a product. Table 2 shows the particle size (mm) distribution (%) of the raw materials used.

[0036]

[Table 2]

The sintering machine is a Dwightroid type (400
m ² ) and the mixing conditions are shown in Table 3 as the raw material mixing ratio.

(Embodiment 2) Next, as shown in FIG. 3, a goethite powder ore of about 10 mm or less was mixed with water in a primary drum mixer and mixed, and this pre-pseudo-wet gel was obtained.
The surface of the site powdered ore is crushed to -1 mm in advance and coated with a converter slag having an average particle size of 0.2 mm or less,
Next, water is added and mixed in the secondary drum mixer, and this mixed ore is stored in the cutting hopper in the same manner as in Example 1,
Next, CaO-containing auxiliary raw material powder (limestone, etc.) and SiO2 -containing auxiliary raw material (silica stone, serpentine, etc.) were adjusted and blended to have a basicity of 1.95 as a flux source, and coke powder as a fuel source. Is added and an appropriate amount of water is added, mixed and quasi-particles are mixed in a tertiary drum mixer, charged into a sintering machine and fired to obtain a product.

The compounding conditions are shown in Table 3. The sintering conditions were the same as in Example 1 in all tests.

As a result, the tumbler strength TI (%) and the reduction powdering index RDI, which are the main items in product quality control,
(%), Reducible JIS-RI (%) and production rate (T /
m ² / H) and the effect of the present invention was confirmed. Table 4 shows the results.

(Example 3) In the same way as in Example 1, the agglomerated mineralization method was used, and the crushed particle size of the converter slag was changed to -0.125 mm particle size content ratio: 10%, 20%, 30% and 40%. The quality of the product is tumbler strength TI (%), reduction pulverization index RDI (%), reducible JIS-RI (%) and production rate ( T / m ² / H) was compared. The results are shown in FIG.

As shown in FIG. 1, it was found that when the grain size of the converter slag was set to -0.125 mm of 30% or more, the quality characteristics and the production rate were good.

(Comparative Example) Next, according to the process diagram shown in FIG. 4, Ca-containing content was obtained without using converter slag as a flux source.
O limestone / quick lime as an auxiliary raw material powder and silica stone / serpentine as a SiO ₂ -containing auxiliary raw material were adjusted and blended to a basicity of 1.95 as in the comparative example shown in Table 3 to obtain a goethite of about 10 mm or less. A coke powder is used as a fuel source in powdered ore, an appropriate amount of water is added, and mixed and added by a drum mixer to form pseudo particles, and the product is produced by a sintering machine.

Then, the quality characteristics and production rate of the product sintered ore were examined in the same manner as in the above-mentioned Examples and compared with those in Examples 1 and 2. Table 4 shows the results.

(Reference Example) Further, according to the process chart shown in FIG. 4, ordinary hematite ore was used as the powder ore, limestone and quick lime were used as the flux, and mixed and granulated by a drum mixer to form pseudo particles. As a reference example, a product manufactured by a sintering machine is shown.

Then, the quality characteristics and production rate of the product sintered ore were examined in the same manner as in the above-mentioned Examples and compared with those in Examples 1 and 2. Table 4 shows the results.

[0047]

[Table 3]

[0048]

[Table 4]

As shown in Table 4, when limestone is used as the flux in the goethite ore of the comparative example, both the yield and the productivity are significantly deteriorated. On the other hand, when the converter slag is mixed and used as a flux instead of limestone, the yield, productivity, and quality are greatly improved, and the product quality and the average quality of the hematite ore that is usually used are The same result as the productivity and yield was obtained.

Further, Example 2 in which the goethite ore was made into pseudo particles and the surface thereof was coated with the converter slag powder
In this case, as shown in Table 4, even better results were obtained.

In the embodiment of the present invention, the agglomerated ore (sintered ore) is manufactured by the sintering machine, but it is needless to say that it can be applied to the pretreatment method of other agglomerated ore manufacturing methods. .

[0052]

By the pretreatment method in the agglomerated ore production of the present invention, the converter slag, which has been more difficult to be dumped than the conventional one, is positively utilized in the agglomerated ore production process, and thus gradually increased. It has become possible to use a large amount of goethite ore, which has a tendency, and to make a great contribution to the industry.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of particle size of a converter slag, agglomerated ore quality and productivity in an example of the present invention.

FIG. 2 is an explanatory diagram of a process used in Example 1 of the present invention.

FIG. 3 is a process explanatory diagram used in Example 2 of the present invention.

FIG. 4 is a process explanatory view used as a conventional example.

Claims (3)

[Claims] 1. When a goethite ore containing water of crystallization is used as a raw material for producing agglomerated ore, converter slag is crushed to -1 mm as a flux, and -0.125 mm is 30%.
A method for pretreatment in agglomerated ore production, comprising adjusting the grain size as described above, adding and mixing the converter slag with the goethite ore to form pseudo-granulate. 2. When using a goethite ore containing water of crystallization as a raw material for producing an agglomerated ore, the powder ore of the goethite ore is pseudo-granulated in advance, and the surface of the pseudo-particle is A pretreatment method in the production of agglomerated ore, which is characterized in that it is pulverized to 1 mm and coated with a converter slag whose particle size is adjusted so that -0.125 mm is 30% or more. 3. The basicity (C
The method for pretreatment in the production of agglomerated ore according to claim 1 or 2, characterized in that it is added and mixed as a substitute for lime within the range of aO / SiO ₂ ).