JP2515639B2 - Method for producing agglomerated ore using converter slag - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing agglomerated ore using converter slag, which uses converter slag as a flux when producing agglomerated ore having excellent properties as a raw material for ironmaking blast furnace. .

[0002]

2. Description of the Related Art FIG. 1 is an explanatory view of a manufacturing process of an agglomerated ore manufacturing method using a normal sintering method. Agglomerated ore, which is a main raw material of a blast furnace, is generally manufactured by adjusting the raw materials as follows according to the process shown in FIG. First, as a raw material, a powder ore of about 10 mm or less (-10 mm) is used as a flux source, as a flux source, CaO-containing auxiliary powder such as limestone, dolomite, converter slag, and S containing silica, serpentine, etc.
Powder coke is used as an iO ₂ auxiliary raw material, return ore, and carbonaceous material as a fuel source, an appropriate amount of water is added, and the mixture is mixed and granulated by a primary and secondary drum mixer. The raw material that has been made into pseudo particles in this way is filled in a great-type sintering machine, the carbonaceous material of the surface layer is ignited, the coke is burned while sucking air from below with the blower, and the raw material is generated by the combustion heat. 11
Sintering at 00 ~ 1300 ° C, then crushing with crusher, screening with 4mm sieve, + 4mm sent to blast furnace as product, -4mm repeated as return ore. The properties of the agglomerated ore produced in this manner are required to be excellent in quality characteristics such as cold strength, reducibility, and reduction pulverization property. 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.

Recently, in order to cope with the high productivity of blast furnaces,
Higher quality is required, and the SiO ₂ content in the product agglomerated ore is about 5.5% or less. Further, with the integration of facilities, a high level of productivity in a sintering machine is required. On the other hand, about 40% of the production of converter slag was landfilled and discarded until about 1980,
Since then, with the tightening of environmental regulations, the amount of landfill waste has gradually decreased, and has recently reached 17-18% (Nagai et al .: Resources and Materials, 107 (1991) No.2, P140). For this reason, the effective use of converter slag is being actively promoted mainly for civil engineering, but not as effectively as blast furnace slag. Focusing on the CaO content in the converter slag and utilizing it as a flux in the sinter production process has been performed for a long time, and many studies have been conducted.

For example, in Japanese Patent Laid-Open No. 55-79837, 100 parts by weight of molten converter slag is added to mineral raw material 1 containing MgCO ₃ such as serpentine and 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. In addition, JP-A-55-128548
The publication discloses a method in which a converter slag is crushed and sized to a particle size of 2 to 10 mm, 1 to 5% by weight is mixed with a sintering raw material, and segregated to a lower layer of a sintering machine to operate. ing.

[0005]

However, when the converter slag is used in the prior art as described above, the agglomerated ore production process, which is the premise thereof, has a relatively low SiO ₂ content and a coke ratio in the product. It was on the condition that it was high and the operation rate was low compared to the current situation. Recently, high-quality agglomerated ore is required for stable and efficient operation of blast furnaces, and management standards such as cold strength, reducibility, and reduced pulverization property have become strict. Therefore, unlike the conventional agglomerated ore, 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. For this reason, the air permeability has been improved by strengthening the pseudo particles of the raw material, and the efficient combustion method has been improved by devising the coke addition method, and the addition amount and method of the auxiliary raw material are restricted to maintain and maintain product quality. Is coming out.

Under such operating conditions, when the converter slag is used, the cold strength is recognized to be lowered, so that there is a problem that the operation with reduced productivity is forced in order to maintain the quality. Moreover, the amount of lime used in the converter has decreased due to the progress of the refining technology in the last 10 years, 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, the SiO ₂ content in the product is 5.5% or less, and the production rate is 1.5 t / m ² / Hr.
It is desired to develop a method for effectively using converter slag in the agglomerated ore manufacturing process under the above conditions.

The present invention has been made in order to solve the problem that it is difficult to dump and recycle converter slag as compared with the above-mentioned conventional ones. It is an object of the present invention to provide an agglomerated ore production method using a converter slag that enables product agglomerated ore to be produced at a high production rate and that can be actively used in the agglomerated ore production process. .

[0008]

The present invention has been made to solve the above problems and achieve the above objects. The present invention has a SiO ₂ content of 5.
In the agglomerated ore manufacturing process with a production rate of 5% or less and a production rate of 1.5 t / m ² · Hr or more, the average particle size is adjusted to 0.4 to 0.6 mm by pulverizing to a particle size of -3 mm (3 mm or less). converter slag was adjusted to a basicity (CaO / SiO _2): 1.8
It is a method for producing agglomerated ore using converter slag, which is characterized in that it is blended so as to maintain 0 to 2.20.

[0009]

[Function] In the converter slag, the main constituent mineral is a high melting point 2
CaO.SiO ₂ and 2CaO.Fe ₂ O ₃ , which have significantly poor assimilation reactivity as compared with limestone (or quick lime) which is usually used as a flux. Next, in order to evaluate the difference in assimilation between limestone and iron oxide and converter slag and iron oxide, each of limestone briquette 1, iron oxide briquette 2 and converter slag briquette 3 was molded at a pressure of 200 kg /
manufactured by cm ^2, limestone briquettes 1 and iron oxide briquettes 2 the combined diffusion couple A, as well as to manufacture a diffusion couple B which is a combination of converter slag 3 and iron oxide 2 was investigated differences in anabolic by firing . The difference in assimilation due to firing of diffusion couples A and B is as shown in FIG. The firing conditions for investigating the state of assimilation were such that each of diffusion pairs A and B was treated in a high temperature atmosphere of 1300 ° C. for 4 minutes in each case.

As is clear from FIG. 2, in the case of the diffusion pair A after firing using limestone as the flux, 1300
The assimilation reaction under the condition of holding at 4 ° C for 4 minutes is remarkable,
Dense calcium ferrite is generated at the contact interface between the limestone briquette 1 and the iron oxide briquette 2. On the other hand, in the case of the diffusion pair B after firing using the converter slag briquette 3, the assimilation reactivity to the iron oxide briquette 2 was poor and the assimilation reaction hardly occurred under the same conditions. This main structure of the converter slag is _{2CaO · SiO 2, 2CaO · Fe} 2 O 3 refractory is due to that the reaction with the iron oxide is markedly suppressed.

However, in the conventional method for producing agglomerated ore, the SiO ₂ content in the product is at a level of 5.5% or more, and the absolute amount of limestone (or quick lime) for slagging this is large, A sufficient amount of melt was generated for sintering. Furthermore, since the production rate is at a level of 1.2 to 1.4 t / m ² · Hr, there was a sufficient margin for the amount of heat required for firing and the holding time at 1100 ° C. or higher. Therefore, even if the converter slag having poor assimilation reactivity was used, there was no particular problem in quality control of the product.

However, the SiO ₂ content in the product is 5.
When producing agglomerated ore for blast furnace under conditions where the production rate is 5% or less and the production rate is 1.5 t / m ² · Hr or more, the converter slag has a normal grain size (-8 mm, arithmetic mean diameter 2 to 3 mm). Is used within the firing time (eg 1300 ° C or higher, 3
(Minutes) causes a decrease in strength of the product agglomerate because the sintering time ends when the assimilation reaction with iron oxide is insufficient. According to the method of the present invention, as shown in FIG. 2, the reaction is performed by reducing the particle size of the converter slag, which is inferior in assimilation reactivity with iron ore to limestone, to -3 mm and the average particle size 0.4 to 0.6 mm. It has been found that the area is increased, the reaction rate in the assimilation reaction with iron ore is improved, and the predetermined quality can be ensured even under the above-mentioned firing conditions (time). In addition, the production rate is favorable. As a result, even if 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 does not decrease in strength of the agglomerated ore. Therefore, the converter slag can be effectively used as a flux source for the production of agglomerated ore without increasing the slag in the blast furnace in the subsequent process.

[0013]

Example 1 A converter slag having the chemical composition shown in Table 1 below was crushed to -3 mm as shown in Table 2 so that the average particle size was 0.4 to 0.6 mm. The particle size is adjusted and Ca is included as a flux source.
O basic material powder (limestone, etc.) and SiO ₂ -containing auxiliary material (silica, serpentine, etc.) and basicity (CaO / SiO ₂ ) are adjusted and blended to 2.0. Its basicity 2.0
In order to maintain the above, the converter slag replaced with limestone was used at two levels of 1.5% and 3.0% addition with respect to the entire blended raw material. Table 3 shows a list of raw material blending ratios. In the production of agglomerated ore, as shown in FIG. 1, raw materials are drawn out from the ore tanks of powdered ore, return ore, powdered coke, and flux according to the composition shown in Table 3, and water is added and mixed by the primary drum mixer. To form pre-pseudo particles, and then water is added and mixed in the secondary drum mixer to form pseudo particles.

The raw material thus quasi-particleized was filled in a Dwightroid type sintering machine (400 m ² ), the carbonaceous material of the surface layer was ignited, and coke was burned while sucking air from a blower from below. , The raw material 11
Sinter at 00 ~ 1300 ° C, then crush with crusher, screen with 4mm sieve, send + 4mm as product to blast furnace, -4mm repeat to return ore tank. In addition, as a comparative example, the case where no converter slag was added and the case where 1.5% of converter slag crushed to -8 mm was blended,
Tumbler strength TI (%), reduction pulverization index RDI (%), reducibility JIS-RI (%) and productivity (T / m ² · H), which are the main items in agglomerated product quality control And the effect of the present invention was confirmed. The results are shown in Table 4.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

As is clear from the comparative example -8 mm converter slag shown in Table 4, when the converter slag crushed to -8 mm was used, comparison was made with the comparative example in which only limestone was used as the CaO source. However, a clear decrease in strength was observed.
On the other hand, a converter slag crushed to -3 mm and adjusted in particle size is blended so that the basicity is the same as 2 when only limestone is used (comparative example), and the same quality as when operating It was maintained, and the same result was obtained in productivity and yield. From this, the particle size of the converter slag is 0.4 ~
When adjusted to 0.6 mm, good results can be obtained in terms of quality and production rate.

[Comparative Example] From the agglomerated ore manufacturing process diagram shown in FIG. 1, the chemical composition shown in Table 1 and the converter slag having a normal grain size (-8 mm, arithmetic mean diameter 2 to 3 mm) were added without addition. 0.5%, 1.0%, 1.5%
The tumbler strength TI (%) and the reduction pulverization index RDI of the obtained agglomerated ore
(%), Reducibility JIS-RI (%) and productivity (T /
m ² · Hr) and the relationship between the amount of converter slag used and the quality and productivity of agglomerated ore. The result is shown in FIG. As shown in FIG. 3, the production rate decreased as the amount of converter slag used increased. This tendency is SiO
₂ It becomes more remarkable when the content becomes lower. It has been found that the cause of the decrease in the production rate is that the reaction of the converter slag with iron oxide is significantly suppressed as shown in FIG.

In this embodiment, the basicity is 2.
It was adjusted and blended so as to be 0, but the range is within the range of 1.80 to 2.20 due to the characteristics of the agglomerated ore to the blast furnace, so that the converter slag can be used. Further, in the present embodiment, the present invention is applied to the production of agglomerated ore (sintered ore) by the Dwightroid type sintering machine, but it is needless to say that the present invention is also applicable to the agglomerated ore production method using other firing furnaces. .

[0022]

According to the method for producing agglomerated ore according to the present invention, 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 can be used without lowering the strength of the agglomerated ore, and the converter slag can be effectively used as a flux source for agglomerated ore production without increasing the slag in the blast furnace in the subsequent process. It became possible and made a great contribution to the industry.

[Brief description of drawings]

FIG. 1 is a process explanatory view of an agglomerated ore manufacturing method used in an example of the present invention.

FIG. 2 is an explanatory diagram showing a difference in assimilation between limestone and converter slag with respect to iron oxide.

FIG. 3 is a graph showing the relationship between the amount of converter slag used and the quality and productivity of agglomerated ore in the conventional method.

[Explanation of symbols]

 1 Limestone 2 Iron oxide 3 Converter slag

Claims (1)

(57) [Claims] 1. The product agglomerated ore has a SiO ₂ content of 5.5.
% Or less and a production rate of 1.5 t / m ² · Hr or more, in agglomerated ore manufacturing process, a converter crushed to a particle size of -3 mm and adjusted to have an average particle size of 0.4 to 0.6 mm A method for producing an agglomerated ore using converter slag, characterized in that slag is blended so as to maintain a basicity of 1.80 to 2.20.