JPS5935969B2 - Method for manufacturing sintered ore - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sintered ore, which strengthens olivine-based slag bonds to reduce the amount of gangue (SiO3 amount) in sintered ore, and improves its high-temperature properties. Another object of the present invention is to obtain a method for producing hard sintered ore that can reduce the blast furnace fuel ratio and the Si content in the pig iron by reducing the blast furnace slag ratio.

The sintering process in a sintering machine such as the toroidroid type involves mixing the raw materials such as iron ore, miscellaneous raw materials, slag forming agents, coke, etc., adding moisture, granulating the material, and then charging it into the sintering machine. By igniting the surface layer of the raw material in an ignition furnace and sucking air downward, the coke in the raw material is burned, and the heat generated causes a sintering reaction or melting of the raw material particles (
By attempting a semi-molten) reaction and cooling it, a mineral composition with high porosity and completely different from that of the raw iron ore is formed.

The goals of such sintering operations are to satisfy quality standards, improve productivity, and reduce coke consumption, so productivity is usually maintained within the range that maintains the quality of the sintered ore. Operations are aimed at improving coke consumption and reducing coke consumption.

By the way, properties required for sintered ore include strength, resistance to reduction and pulverization, reducibility, high temperature properties, etc., but when trying to satisfy all of these properties,
In many cases, the conditions for satisfying each property are contradictory (e.g., to avoid powdering in a reducing atmosphere in the temperature range of 500 to 600°C, and to improve resistance to reduction powdering, it is necessary to increase the coke ratio or Although increasing the amount of gangue is effective, these actions have the disadvantage of deteriorating the reducibility and coke ratio and increasing the blast furnace fuel ratio.

Therefore, in actual operation, priority is given to the required properties as described above, and the plant is operated at 5Kt in order to obtain the maximum production within the control limits.

However, as a result of recent load softening and melting tests aimed at more accurate measurement and evaluation of the high temperature properties (reducibility, softening and melting characteristics at high temperatures, and changes in air permeability due to these) of blast furnace charging raw materials, The causes of differences in the high-temperature properties of sintered ore are directly due to the amount of melt produced during the slag assimilation reaction process, and indirectly due to the reducibility at high temperatures of 1000°C or higher and the temperature before reduction. It was found that the gangue composition and amount are particularly important, and among these, the reduction in the amount of gangue in sintered ore (CaO / SiO It was also confirmed that the blast furnace fuel ratio could be significantly reduced.

However, SiO2 which reduced the amount of gangue in sintered ore in this way
Sintered ore with a low 5i02 coefficient of 5.2 or less is easily pulverized in the reducing atmosphere in the temperature range of 400 to 600°C in a blast furnace, and the reduction pulverization index ( RDI: After 900 rotations of sintered ore held in a reducing atmosphere at 550°C for 30 minutes, the weight ratio of 13 mm (weight ratio) deteriorates significantly, and the sintering time becomes longer, resulting in a decrease in production rate or production The disadvantage is that the yield and strength (si) are reduced when the ratio is kept constant.

Regarding the production of this low-SiO□ sintered ore, there have been several proposals by Mr. Tashiro et al., but these proposals involve increasing the amount of SiO□ in the fine powder portion of less than 1 min by pulverizing the SiO2 source. Seshime, this fine powder part Cab
/Sin□mata&j-CaO/ (S 102-Ae20
3) is made below a certain level, or the fine powder portion is made more than 55, and the raw material preheating of the finely adjusted powder is also used, in short, the silicate slag bond expected with the reduction of SiO2. The aim is to compensate for the decrease in production by pulverizing the 5i02 source and increasing the effective amount of SiO□.

However, even if low SiO2 is achieved by using K, there is a limit as long as silicate slag is used as a bond.Therefore, in order to obtain a desirable low SiO2 for sintered ore, considerable selection must be made regarding the brand of ore to be blended. In addition, from this point of view, it is impossible to continue for a long period of time, and it is difficult to continue stable low 5i02 operation.

The present invention was created after repeated studies in view of the above-mentioned circumstances, and is intended to be applied to ores containing 6 or more FeO, such as scales, eruption slag, converter slag, sieve slag, and dust. Part or all of the miscellaneous raw materials are pulverized to adjust the particle size, and the Fed/5in2 in the fine powder part of less than 1 tom is 0.8 to 2.3.
It is proposed that the amount of 5i02a in the sintered ore should be adjusted to 4.6 to 4.6.
It is proposed to adjust the S i02 content of the blended raw materials so that it becomes 5.4.

That is, by controlling Fed/5in2 in the fine powder portion to a high value as described above, it is possible to promote and strengthen the formation of olivine-based slag bonds in addition to the conventional silicate-based slag bonds, thereby obtaining a preferable sintered ore. reduction index (RDI) without deteriorating productivity or coke consumption rate.
This makes it possible to obtain appropriate cold strength (SI) and to reduce the amount of gangue (Si02 amount) in the sintered ore.

In addition, regarding the present invention, to explain further, in the sintering reaction of self-fusing sintered ore, there is little diffusion bonding as a solid phase reaction (but most of the bonding is through the molten phase, so there is no molten liquid Q: The role it plays is extremely important.

The equilibrium structure is a so-called fusion bond type in which slag particles such as iron oxide particles are bonded, and the quality and productivity of the sintered ore are greatly influenced by this slag bond.

However, in the current process using a Dwight Lloyd sintering machine, the reaction time at high temperatures is extremely short (and since the heating is not completed until it reaches a completely molten state, bonding proceeds through the partially formed melt). An important issue is how to quickly and uniformly convert gangue into slag.

This is especially important when manufacturing sintered ore with low SiO□ with a small amount of gangue. It is necessary to compensate by some means.

By the way, in sintering, a melt is generated from a combination of particles that are likely to generate a melt (a combination of particles corresponding to a chemical composition region with a low melting point) among mixed powders with various chemical compositions. ,
It is assumed that the amount increases and spreads as the temperature rises, and that the bonding progresses through reactions and coalescence between the melts, but if the residence time at high temperatures is short as described above, coarse grain raw materials or slag formation will occur. Inferior raw materials often remain unreacted without being completely melted.

As a result of careful consideration and repeated experiments on these points, the present inventors have found that by pulverizing ores with high FeO content of 6 or more or the above-mentioned miscellaneous raw materials, a fine powder portion of less than INN is obtained. F e O/S i O □ at 0.8
Adjusting the particle size to ~2.3 is the best way to ensure productivity and coke consumption appropriately, and improve the reduction index (RDI) and cold strength (SI) mentioned above. This is a key point, or also this RDI value or SI
It was confirmed that this is a key point in reducing the amount of gangue (SiO□ amount) in sintered ore while maintaining the same value.

By the way, during the mixing and granulation process of the sintered raw material, as shown in Fig. 1, pseudo-particles are formed with coarse grains of 5VC1 to 5 as cores and fine particles of less than KO, 5 or more adhering to the surroundings. The generation of slag melt starts from this attached fine powder raw material, and sintering progresses by gradually dissolving the surrounding coarse grain raw material, so this slag melt is necessary to improve reduction powdering properties and cold strength. It is necessary to rapidly produce and to produce to a certain extent.

In Figure 2, the low melting point region below 1150°C of the FeQ-8102-CaO system is shown as D. FeO/S i0 in the fine powder part
2 was controlled at 0.8 to 2.3 K, and olivine-based (CaO5
102Fed) By making it easier to quickly generate slag, it is possible to produce sintered ore with excellent reduction powdering resistance and cold strength without deteriorating productivity and coke consumption.

Furthermore, it is possible to reduce the amount of gangue within a range that does not deteriorate reduction powdering properties and cold strength.

In other words, even if the amount of gangue (SiO2 amount) is reduced, olivine-based slag bond is effectively generated in addition to the conventional silicate-based slag bond, so the amount of gangue can be reduced without deteriorating productivity, coke consumption, or quality. This makes it possible to improve high-temperature properties, reduce the blast furnace fuel ratio by reducing the blast furnace slag ratio, and reduce Si in the pig iron.

Specific examples according to the present invention are shown below together with conventional examples and reference examples for comparison.

Example 1 The following brands of iron ore, limestone, dolomite, silica stone, coke, return ore, etc. were prepared, and conventional example 1 using these materials is as shown in Table 1 below.

-1mm5iQ2== 2.58 -17n? +! FeO−= 1.57 −1 mmFeo/S i02 = 0.61 this first
What is shown in the table is Si with reduced 5i02 source using the usual method.
Reference Example 1 with a blend of O2: 5°4 is as shown in Table 2 below.

−11m5iO□=2.35 −1 mmFe0=1.57 1 mmFeo/S to 2 =, 0.67 Contrary to these, specific formulation examples of the products according to the present invention are as shown in Table 3 below. Then, part or all of the ore or miscellaneous raw material with high FeO is pulverized to adjust the particle size, and the FeO/SiO2 of the fine powder portion less than 111 Lm is adjusted to 0.95, which is within the range of 0.8 to 2.3. However, SiO□ in the sintered ore
In order to reduce the amount, silica stone and serpentine are cut and the blend of dolomite and limestone is adjusted.

-1 關SiO□-2,46 -1 mmFe0 :=2.34 1 mmF eO/S t02 = O-95 These compounded raw materials shown in Tables 1 to 3 were granulated by adding water, and Negative pressure 130
The suction was carried out at 0 m'11 Aq to produce pot sintered ore.

Production rate, strength, product yield, and
The reduction ratio (RDI) and RI value are shown in Table 4 below.

In other words, compared to Conventional Example 1, Reference Example 1 has its S
As the amount of iO□ decreases, the production rate, strength, product yield, and RDI deteriorate, and the sintering operation and properties of the sintered ore greatly deteriorate.

In contrast to these products, the product of Example 1 of the present invention, in which the F e O/S t O2 of the fine powder component with a VC of less than 1 mm was adjusted to 0.95, has improved strength, product yield, and RDI without deteriorating the production rate. and RI could be improved respectively.

Example 2 The formulation of Conventional Example 2, which also used serpentine, is as shown in Table 5 below.

-1xis i02 == 2.42 -1 mmFe0 = 1.59 1 mm F e O/St 02 =0.66 Then, the amount of Si02 is reduced by a conventional method to produce a low 5i02 sintered ore. The composition of Reference Example 2 was as shown in Table 6 below.

−1m5i02=2.04 −1 m1FeO=1.51 −1m1Feo/5i02=0.74 Furthermore, according to the invention, F
By pulverizing eO ore or miscellaneous raw materials, the FeO,/5i02 of the fine powder part of less than 1 min is within the scope of the present invention and 1.09, and in addition, dolomite and lime are used by cutting silica and serpentinite. The formulation of Example 2 of the present invention, in which the formulation was adjusted, is as shown in Table 7 below.

-1 mm 5in2 = 2.14 -1 mrnFeO = 2.34 1 mmF eO/S t 02 = 1.09 For each of the formulations shown in Tables 5 to 7, Example IV
Sintered ore is manufactured in the same manner as in C, and its production rate, strength,
The results of measuring product yield ≧ are summarized as shown in Table 8 below, and in the same way as described for Example IK, reference column 2 shows the production rate, strength, product yield and It was confirmed that while the RDI deteriorated, the product according to Example 2 of the present invention significantly improved them.

According to the present invention as explained above, strength, product yield, resistance to reduction powdering, etc. can be effectively improved without impairing productivity, and the amount of gangue in sintered ore can be reduced. At the same time, it is possible to accurately produce an advantageous sintered ore that improves high-temperature properties, reduces the blast furnace slag ratio, reduces the blast furnace fuel ratio, and reduces the Si content in pig iron, so it is industrially effective. This is a great invention.

[Brief explanation of the drawings] The drawings show the technical contents of the present invention. Figure 1 is a chart showing the relationship between powder adhesion rate and particle size distribution, and Figure 2 is a diagram showing the relationship between powder adhesion rate and particle size distribution.
FIG. 2 is an explanatory diagram showing a low melting point region of 1150° C. or lower in the i02 FeO system.

Claims (1)

[Claims] I Part or all of the ore or miscellaneous raw materials containing 6% or more of FeO is pulverized and the particle size is adjusted so that the FeO/5i02 of the fine powder portion of less than 1 tom is 0.8 to 2.3. A method for producing sintered ore by sintering blended raw materials adjusted in this way. 21 FeO/5i02 of the fine powder part of Tomomi drop is 0.8 to 2
．． SiO□ of the VC compounding raw material was adjusted so that the 5i02 content of the sintered ore was 4.6 to 5.4.
The method for producing sintered ore according to claim 1, wherein the content is adjusted.