JP2000178659A - PRODUCTION OF HIGH QUALITY LOW SiO2 SINTERED ORE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of sintered ore excellent in reducibility, reduced powdering property and high temp. characteristics, with which the component adjustment of MgO in slag in the operation of a blast surface is unnecessary and SiO2 content in the sintered ore is lowered to 4.6% without lowering the producing ratio and the yield in the sintering process. SOLUTION: In the production of the sintered ore for blast furnace, having <4.6% SiO2, 1.0-3.0 basicity and >0.5% MgO in the product, as the MgO source, magnesite 5 and/or brucite 6 are used without using either of SiO2.MgO base auxiliary raw material such as serpentine or CaO.MgO auxiliary raw material such as dolomite, to adjust the slag component composition in the sintered ore product. The sintered ore excellent in the reducibility and reduced powdering property can stably be produced in the high production ratio and the high yield, and the fuel ratio and the slag ratio in the blast furnace are reduced and the blasting operation of high ratio of pulverized fine coal can be attained.

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 a low SiO ₂ sintered ore having a high production rate, a high yield, and excellent reducibility (RI) and reduced pulverizability (RDI).

[0002]

2. Description of the Related Art A sintered ore used as a raw material for a blast furnace is generally produced by the following method. First, iron ores unloaded from the Vessel are piled up in the fine yard by brand.
Thereafter, it piled various powder ore, containing CaO auxiliary material, containing SiO ₂ auxiliary material, mixed by bedding method at a rate that is set in advance dust and carbonaceous material such as, a blending powder. This blending powder, limestone and / or quicklime, quartzite and / or serpentine, coke breeze and / or anthracite, and return ore, and in some cases, raw materials such as plain ore, are put into separate compounding tanks. A predetermined amount of each raw material is continuously cut out from each mixing tank. Then, an appropriate amount of water is added to the cut out raw materials, mixed, and granulated.

[0005] The sintering material in the form of quasi-particles thus granulated is continuously placed on a pallet of an endless moving great type sintering machine (Dwyroid type sintering machine) by a hopper for 500 minutes.
It is supplied to a layer thickness of about 700 mm. Next, the carbon material in the surface layer is ignited by an ignition furnace, and the carbon material is burned while forcibly sucking air downward, and the combustion heat generated at this time sinters and agglomerates the compounded raw material. I do. The sintered cake thus baked is cooled, crushed, and sized to obtain 3
Particles of ５5 mm or more are charged into a blast furnace as a product sintered ore. Fine powder ore having a size of 3 to 5 mm or less generated in the crushing and sizing process is used again as a raw material for sinter ore.

[0004] The quality characteristics of the sintered ore produced as described above include cold strength, reducibility and reduced pulverizability.
These greatly affect the stable and efficient operation of the blast furnace.
Therefore, these quality characteristics are particularly strictly controlled. On the other hand, in terms of sinter production costs,
Low energy consumption per unit of electricity and high production rate
High yield is required. More recently, there has been an increasing demand for reducing slag, which is a by-product of blast furnace generation, as much as possible in response to environmental measures and energy conservation. In view of the above background, many techniques relating to sinter quality, production rate, and yield improvement have been proposed.

In general, as a method for improving the reducibility and high-temperature properties of sinter, the amount of slag in sinter, and
₂ It is known that reducing the content is effective. However, the cold strength, the yield, and the reduced pulverizability are in conflict with each other, and there are many difficulties to improve both.

[0006] As a method of reducing the SiO ₂ content in the sinter, there are generally a method of using iron ore having a low SiO ₂ content and a method of reducing the amount of SiO ₂ -containing auxiliary materials such as silica stone and serpentine. There is a way to be done. In the former method, since high-grade ore must be used, it is difficult to stably produce sinter for a long period of time, and the cost is high. Therefore, the latter method is often employed. For example, Japanese Patent Publication No. 58-1180 discloses a method for adjusting the particle size of silica to be added to a sintered ore to less than 1 mm (referred to as prior art 1), and Japanese Patent Publication No. 52-72.
No. 1 discloses a method of adding fine nickel slag as a raw material for adjusting pseudo particles (prior art 2).
). However, in these methods, it is necessary to procure and adjust a slag-making agent which is originally unnecessary, and cannot be an ultimate method for producing low SiO ₂ sintered ore.

On the other hand, as a method for reducing the content of SiO ₂ in the sinter, if the content of MgO · SiO ₂ -based auxiliary materials such as serpentine is reduced, the content of MgO in the sinter is ensured. It is known that high-temperature properties of the sintered ore in the blast furnace deteriorate. In addition, in order to adjust the slag viscosity in the blast furnace, Mg-containing auxiliary materials such as serpentine must be separately charged into the blast furnace, and the slag ratio in the blast furnace operation (the amount of slag generated by the production of 1 t of hot metal) There is a problem that reduction of the amount cannot be achieved. Therefore, conventionally, in order to secure the MgO content in the sintered ore while keeping the SiO ₂ content low, a method using an MgO.CaO-based auxiliary material such as dolomite or lightly calcined dolomite has been proposed, for example, in Japanese Patent Application Laid-Open No. 9-143580. Japanese Patent Application Laid-Open Publication No. H11-15064 discloses a production method combining particle size adjustment of these auxiliary materials and a stirring mixer (referred to as prior art 3). However, M
In the method for producing a low SiO ₂ sintered ore using the gO · CaO-based auxiliary material, MgO slagging property during calcination is poor, so that free CaO indispensable for melt generation is reduced. A decline is inevitable.

As described above, at present, a general-purpose method for securing the MgO content in the sintered ore and improving the reducibility, reduced pulverizability, and high-temperature properties without lowering the sintering productivity. No production technology for low SiO ₂ sintered ore is found.

[0009]

The sintered ore as a raw material for the blast furnace must contain an appropriate amount of MgO in order to ensure high-temperature properties in the furnace and to reduce and powderize. is necessary. However, as described above, in the production of sintered ore, in order to secure the reducing and high-temperature properties in terms of quality, to secure the production rate and yield in terms of operation, and not to increase the slag ratio generated from the blast furnace, As a method for securing MgO of a predetermined content, it is not appropriate to use serpentinite or dolomite which has been conventionally used as a MgO source. In addition, to increase the ratio of effective SiO _{2 in} the mixed silica to reduce the amount of silica used, such as fine grain size adjustment, etc.
Auxiliary raw material pretreatment is costly.

Therefore, according to the present invention, it is not necessary to adjust the composition of MgO in the slag in the blast furnace operation. On the other hand, the SiO ₂ content in the sinter is reduced without reducing the production rate and the yield in the sintering process. It is an object of the present invention to develop a method for producing a sintered ore excellent in reducibility, reduction pulverizability and high-temperature properties by lowering the sinter to a predetermined value. Here, the upper limit of the SiO ₂ content in the sintered ore was set to 4.6% for the reason described later.

[0011]

SUMMARY OF THE INVENTION From the above-mentioned viewpoints, the present inventors have developed a method for producing a high-quality sintered ore, and added MgO to a sintered ore, which is effective for solving the above problems. Materials suitable as sources were investigated and tested. As a result, the following findings were obtained.

As a source material of the MgO component in the sinter,
Magnesite and bruteite correspond to those having a high MgO content, particularly a low SiO ₂ content, and containing substantially no harmful components as slag components or having no real harm even if they are included. I do. That is, both magnesite and bruteite contain a large amount of magnesium carbonate MgCO ₃ as a main component, and Si
The contents of O ₂ , Al ₂ O ₃ , CaO and the like are low. Therefore, the ignition residue is mainly composed of MgO, and the ignition loss accounts for one half to one third of the whole.
The loss on ignition is removed in the firing process of the sinter. In addition, magnesite and bruteite are both less expensive than conventional MgO source materials, have large reserves, and have stable supply and demand. Therefore, magnesite and / or bruteite are used as the MgO source material in the sinter,
In addition, all of the above-mentioned problems can be solved if neither the SiO ₂ .MgO-based auxiliary material such as serpentine nor the CaO.MgO-based auxiliary material such as dolomite is used.

The method for producing a low SiO ₂ sintered ore according to the present invention has been made based on the above findings, and has the following contents. The method for producing a high quality low SiO ₂ sintered ore according to claim 1 is a sintered ore which is a raw material to be charged into a blast furnace, wherein the product has a SiO ₂ content of 4.6% or less and a basicity of 1 or less. 0.03 to 3.0, and the MgO content is 0.5%
In the method for producing a sintered ore having more than one, one or both of magnesite and bruteite as an MgO addition source auxiliary material are used, and any of a SiO ₂ .MgO based auxiliary material and a CaO.MgO based auxiliary material is used. Without even using
It is characterized in that the slag component composition in the sintered mineralized product is adjusted.

Further, the method for producing a high quality low SiO ₂ sintered ore according to the _{second aspect} of the present invention is characterized in that, in the invention of the first aspect, serpentine is not used as a representative substance of the SiO ₂ .MgO-based auxiliary raw material, Further, it is characterized in that dolomite is not used as a typical substance of the CaO.MgO-based auxiliary material.

[0015]

Next, an example of a preferred embodiment of the present invention will be described. Table 1 shows typical raw materials for sinter production according to the method of the present invention and examples of their component compositions. For reference,
Examples of component compositions of dolomite and serpentine are also described. FIG. 1 shows a schematic flow of the sinter production process.

[0016]

[Table 1]

As the main raw material, the mixed powder 1, the ore and the ore 4 mixed by the bedding method, or the mixed powder 1 and the ore 4 are used, and the coke breeze 7 is used as the solid fuel. Limestone 2 and / or quicklime 3 as a CaO component addition source, and M among slag components
A magnesite 5 and / or a bruteite 6 are added at a predetermined ratio for adding a gO component, and the SiO ₂ content is 4.
6% or less, basicity CaO% / SiO _2% is 1.0 to 3.
0 and the MgO content is more than 0.5%. Moisture 8 'is added to the compounded raw material thus obtained, mixed and conditioned 8 by a drum mixer 8, and then granulated by a drum mixer 9 or granulated by a disc pelletizer 10, and appropriately coke powder 7' To prepare pseudo particles. The sintering raw material prepared into the pseudo particles is charged in a layer on a grating of a firing furnace, and then the upper layer surface is ignited, and the coke breeze is burned by suction downward to perform firing to produce sintered ore.

Since SiO ₂ in the sinter increases the amount of slag melt in the sinter in the blast furnace, and particularly has an adverse effect on the reducing properties and high-temperature properties, restrictions on the slag composition in the blast furnace, for example, Under operating conditions in which the upper limit range of the Al ₂ O ₃ content is not set, it is desirable to lower the content as much as possible. However, as described above, in the method of adjusting the decrease in the SiO ₂ content by using a high-grade iron ore raw material, it is difficult to achieve long-term stability due to supply and demand and cost restrictions. Therefore, it is necessary to accept the mixing of SiO ₂ originating from the use of recycled materials in steel works, and to satisfy a predetermined quality level without using any other slag-making agent as a mixing source of SiO ₂ . Here, the predetermined quality level varies depending on the sintering machine and the blast furnace operating conditions, but generally, the JIS reduction rate RI is about 70% or more, the reduction pulverization index RDI is 40 or less, and the tumbler strength TI is 70 or more. In order to secure a high level, the SiO ₂ content was limited to 4.6% or less. As described above, by reducing the SiO ₂ content in the sinter, firelite (2FeO.Si
It also has the effect of suppressing the generation of non-reducible substances such as O ₂ ) and improving the reducibility. Further, the basicity is within a practical range of 1.0 for securing the strength of the sintered ore and for charging the blast furnace.
Should be between ~ 3.0.

Next, high-temperature properties in the blast furnace are secured,
In particular, in order to improve the reduction pulverizability, it is important to secure an MgO component having a predetermined content or more in the sintered mineralized product. However, when the MgO content is 0.5% or less, the M
The effect of gO is not always sufficiently exhibited in consideration of the fluctuation of the composition of other components in the sintered mineralized product. On the other hand, Mg
When the O content is increased to about 2.0%, slag of the slag in the sintering raw material is deteriorated in the sintering process, and the sinter production rate is reduced. If the MgO content is secured at about 1.5%, the function and effect are sufficiently exhibited. In addition, it is advantageous to reduce the MgO additive material in terms of cost reduction. Therefore, the upper limit of the content is not limited by the balance between the merits and demerits of adding the MgO component. As described above, the content of MgO in the sintered mineralized product is limited to more than 0.5%.

Here, if the particle size of magnesite 5 and / or bluestite 6 is the same as that of other raw materials such as ore for sintering and other auxiliary raw materials, the particle dispersion in the mixing and granulating steps is more uniform. The effect of the addition of MgO is more fully exhibited, and the effect of improving the quality such as the reduction pulverizability is particularly increased.
Magnesite and bruteite having a particle size of about 10 mm or more are used as other products, but finer particles have no effective use destination, so that they are more preferably used in the production of the sintered ore of the present invention. .

The proper range of the mixing ratio of the coke breeze varies depending on the granulation method and the addition method, but from the viewpoint of the production rate and the maintenance of the yield, and from the viewpoint of the prevention of overmelting for improving the reducibility and reduced pulverizability. Therefore, about 35-45 kg / t-product is suitable.

[0022]

Next, the present invention will be described in more detail by way of examples. Examples 1 to 6, which are methods within the scope of the present invention, and conventional methods, which are methods outside the scope of the present invention, according to the sinter production flow shown in FIG. 1 by appropriately using the raw materials having the chemical composition shown in Table 1. Sinters were produced by methods 1 to 3 and comparative examples 1 and 2, respectively. However, in the conventional method and the comparative example, serpentinite (not shown) and dolomite (not shown) were appropriately used as auxiliary materials in the production flow of FIG. Tables 2 and 3 show the raw material formulations in the conventional method, comparative examples, and examples. Table 4 shows the particle size distributions of magnesite and bluestite used in the examples.

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

A sintered ore was manufactured under the above conditions. Then, the chemical composition of each sintered ore product was analyzed, the operation results of the sinter production were investigated, and the quality test of the sinter was performed. Table 5
And for each of the tables 6 shows a conventional method and the comparative examples as well as sintered ore-products of chemical composition and basicity produced in Example a _{(C / S≡CaO% / SiO 2} %). FIG.
FIG. 3 shows the quality test results and operation results of the sintered ore manufactured by the conventional method and the comparative example, and FIG. 3 shows the quality test results and operation results of the sintered ore manufactured by the example. The quality evaluation of sinter is based on the cold strength of JIS tumbler strength TI.
The reducibility was evaluated by the JIS reduction ratio RI, and the reducible pulverizability was evaluated by the reductive pulverization index RDI of the Iron and Steel Institute of Japan.

[0027]

[Table 5]

[0028]

[Table 6]

In the conventional method 1, in the raw material blending, the MgO content in the sintered ore is set to a desired target value of 1.5% for the product.
The composition was adjusted using serpentine so that The serpentine, since MgO and contain approximately level content of SiO ₂ is also, with the adjustment of the MgO content, rose SiO ₂ content in ShoyuikoNaru products 5.3%, the Invention SiO
_{2 The} content exceeded the upper limit of 4.6%.
As a result, a high value was not obtained for the RI of sintered mineral products,
No good reducibility was obtained.

In the conventional method 2, in the raw material blend, the SiO ₂ content in the sinter was limited and adjusted so as to be 4.5% which is 4.6% or less which is the upper limit of the product of the present invention. in this case,
The mixed powder-A and HAM-F, which are the main raw materials, contain only SiO ₂
Since the content has almost reached the upper limit, a new Si
No O ₂ source material was added. That is, serpentine for adding the MgO component was not used. Therefore, MgO in the sintered mineralized product has a desirable target value of 1.5%,
Neither was it possible to secure the lower limit of 0.5% or more for the product of the present invention. As a result, the RDI of the sintered mineralized product showed a high value,
Good reducible powder was not obtained.

In the conventional method 3, in the raw material blending, the MgO content in the sinter is desirable in the product while suppressing the rise of SiO ₂ by using only the mixed powder-B having a low SiO ₂ content as the main raw material. Serpentine was blended and adjusted to reach the target value of 1.5%. However, since the serpentine contains SiO ₂ of substantially the same height content and MgO, serpentinite for dissolution and assimilation reactions to the initial melt (calcium ferrite) is poor, sintered ore strength decreases In addition, the reducing property is not improved due to the non-uniform structure. Therefore, RI7 of the conventional method 3
Comparative Example 2 in which the main material use conditions are exactly the same as 0.5%
Moreover, it was not larger than the RI (= 78 to 80) of Examples 4, 5, and 6, and the reducibility was not improved.

In Comparative Examples 1 and 2, in the raw material blend,
When securing the MgO content in the sinter to 1.5%, dolomite was used to keep the SiO ₂ content low. However, since dolomite contains MgO having poor slagging properties, the generation of a melt during firing was insufficient, and the production rate and yield of sinter decreased. In order to avoid this, it is necessary to perform processing such as finely adjusting the particle size of the dolomite.

On the other hand, the production conditions of the sinter in the examples were as follows. That is, using as a ore a mixed powder-A and a mixed powder-A or a mixed powder-B having a low SiO ₂ content, and using either serpentinite or dolomite at all, either one of magnesite or brucite. Alternatively, the MgO content in the sintered mineralized product was adjusted to approximately 1.5% using both magnesite and bruteite, and the SiO ₂ content was kept low. Here, the SiO ₂ content was set at two levels of 4.5% and 3.5%. These low SiO ₂ contents indicate that the ore used was mixed with the above-mentioned Hamasley-F and mixed powder.
This is achieved by using A and by using the mixed powder-B and not using serpentine used in the conventional method. The basicity was adjusted to a level of 2.0.

In each of the sintered ores produced in the above examples, the content of SiO ₂ in the sintered mineralized product is low, the content of MgO is maintained at a predetermined value, and the quality is reduced, reduced powdered. Not only is it excellent in heat resistance and cold strength, it is also excellent in both sinter production rate and product yield. This is because, as a method of adjusting the MgO content in the raw material mixture of the sinter, instead of using dolomite or lightly burned dolomite, magnesite and / or bluestite can be used to avoid poor slagging of MgO. It is due to.

[0035]

As described above, according to the present invention,
In order to adjust the MgO content, S represented by serpentine
Without adding an iO ₂ .MgO-based auxiliary material or a CaO.MgO-based auxiliary material represented by dolomite and lightly fired dolomite, the SiO ₂ content is 4.6% or less and the MgO content is 0.5% Exceeding low silica sinter can be produced. By using this sinter, M in slag in blast furnace operation
It is not necessary to adjust the composition of gO. On the other hand, while maintaining the production rate and the product yield in the sintering process at the conventional good levels, the SiO ₂ content in the sinter is reduced to reduce the reducibility and reduced powder. It is possible to stably produce a sintered ore excellent in chemical properties and high-temperature properties at low cost. As a result, it is possible to achieve a reduction in the fuel ratio and slag ratio of the blast furnace, or a high pulverized coal injection operation. A method for producing such a high-quality sintered ore can be provided, and an industrially useful effect is provided.

[Brief description of the drawings]

FIG. 1 is a schematic flow chart showing an example of a sinter production process suitable for carrying out the present invention.

FIG. 2 is a graph showing quality test results and operation results of sintered ores manufactured by a conventional method and a comparative example.

FIG. 3 is a graph showing quality test results and operation results of the sintered ore manufactured in the example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mixed powder 2 limestone 3 quicklime 4 fly ore 5 magnesite 6 bluestite 7, 7 'coke breeze 8 drum mixer 8' moisture 9 granulator 10 disk pelletizer 11 coating mixer 12 sintering machine 13 blower

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Koichi Ichikawa, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Nihon Kokan Co., Ltd. (72) Noboru Sakamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan (72) Inventor Hideaki Sato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan 1-2.Inventor Takashi Watanabe 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan 1-2 Inside (72) Inventor Ken Hashimoto 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4K001 AA10 BA02 BA05 CA33

Claims (2)

[Claims] 1. A sinter which is a raw material to be charged into a blast furnace, wherein the product has an SiO ₂ content of 4.6% or less, a basicity within a range of 1.0 to 3.0, and an MgO content. 0.5% rate
In the method for producing a sintered ore having more than one, one or both of magnesite and bruteite as an MgO addition source auxiliary material are used, and any of a SiO ₂ .MgO based auxiliary material and a CaO.MgO based auxiliary material is used. Without even using
A method for producing a high quality low SiO ₂ sintered ore, comprising adjusting a slag component composition in the sintered ore product. _2. The method for producing a high quality low SiO ₂ sintered ore according to claim 1, wherein said SiO ₂ .MgO based auxiliary material is serpentine and said CaO.MgO based auxiliary material is dolomite.