JPS5852447A - Manufacture of unfired lump ore - Google Patents

Abstract

PURPOSE:To obtain unfired lump ore for a blast furnace with favorable properties at high temp. by specifying the grain size of ore as a starting material, adding a secondary starting material, a solid reducing agent, a binder, etc., and filling and binding them to a prescribed size. CONSTITUTION:The grain size of iron ore-base fine ore is adjusted to 0.5-8mm.. The granules are mixed with a secondary starting material, a solid reducing agent, a binder and water as required, and the mixture is filled into a container or the like, bound and crushed. By this method unfired lump ore with favorable properties at high temp. such as satisfactory reducibility and pressure drop is obtd. even when low grade ore is used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing uncalcined X-burning ore used in a blast furnace, and an object of the present invention is to impart good high-temperature properties to the method.

The three properties required for uncalcined agglomerate used in blast furnaces are: ■ high cold strength, ■ low pulverization during R, and ■ high softening concentration. However, no uncalcined agglomerated ore that satisfactorily satisfies these properties has been obtained so far.

A typical example of non-calcined agglomerate ore is cold bond pellets, which are produced by adding auxiliary materials, a binder, and appropriate moisture to fine ore, and the production flow is shown in Figure 1. Mix fine ore with particle size, auxiliary raw materials and cement, and use a pelletizer to reduce the mixture to particle size 10.
After curing the granulated material to a size of ~20 ff and achieving sufficient strength to withstand handling, it is used as a blast furnace charge.

However, in the case of cold bond pellets, the mori and
As shown in FIG. 2, the surface becomes a metallic iron layer (F) reduced to metallic iron, and the inside becomes iron oxide scrap (0) reduced to FeO. The mixture of FeO and gangue is usually 1150
Begins to melt at ~1200℃, Fe at about 1250℃
The O phase melts. As a result, a dense structure is formed in the metallic iron layer and reduction stagnation occurs, and since the iron oxide layer inside has fluidity, the packed layer of the pellet shrinks and the porosity decreases, leading to an increase in ventilation resistance. . As described above, cold bond pellets have poor high-temperature properties, so they have not been perfected as blast furnace charges.

Therefore, several methods have been proposed to improve the high-temperature properties of cold bond pellets. As methods for this, [engineering] a method of improving susceptibility and [I] a method of improving gangue composition are known. However, these methods have the following first-order problems.

(I) Improving reducibility There are two ways to improve reducibility: increasing the porosity to improve the flow of reducing gas into the particles, and adding a solid reducing agent such as coal or coke powder. . However, the method of increasing the porosity increases the reducibility, but as the porosity increases, the cold strength decreases.

This is not preferable because it lowers the strength during the reduction process and causes powdering. Also, in the method of mixing a solid reducing agent, the cold strength decreases and powdering during reduction becomes large, which is not preferable as a blast furnace charge.

rI[) Improvement of gangue composition This method is a method of adjusting the gangue composition to raise the melting start temperature and reducing the amount of gangue to limit the amount of melting. As described above, the high-temperature properties of the cold bond pellet depend on the melting properties of the F.0 phase remaining inside. This FeO phase is different from FeO and the amount of gangue), and the part mainly composed of gangue melts at 1150 to 1200℃, and as the temperature further increases, the part mainly composed of FeO melts, but the part mainly composed of FeO If the amount of stones is large, even if the gangue composition is adjusted, F
The eO-based phase melts at a temperature of at most 1250°C. For this reason,
In the case of cold bond pellets, it is necessary to proceed with the reduction considerably at a temperature of 1250° C. or less, which is difficult due to the reduction rate of normal cold bond pellets.

Therefore, it is not preferable to improve the high-temperature properties by adjusting the composition and amount of gangue, and the ore used is limited to high-grade ore with a small amount of gangue.

The present invention has been made to solve the above-mentioned conventional problems and to obtain unfired agglomerated ore having good high-temperature properties.

That is, the present invention provides a method for producing non-calcined agglomerate ore, in which granular ore mainly composed of iron ore is agglomerated by adding auxiliary raw materials, a binder and, if necessary, water. The method is characterized in that granules of .5 to 8 mm are obtained, and if necessary, auxiliary raw materials, a solid reducing agent, a binder, or water are added to the granules and then filled and bonded to a predetermined size.

In the case of cold bond pellets, the improvement of high temperature properties is primarily to sufficiently promote reduction. It is self-evident that reducing the pellet diameter is effective as a method for promoting reduction in addition to the conventional method described above. Conventionally, this was not used because the ventilation resistance in the area would be large.

However, as a result of various studies on methods for measuring the reducibility of china clay in cold bond pellets by reducing the pellet diameter, the inventors found that the particle diameter was 8. By using raw materials with a size of 0.5 to 8 cm and granulating them to a size of 0.5 to 8 cm, and then filling and bonding them to a predetermined size, the reducibility can be improved without increasing ventilation resistance. I found out.

That is, the present invention provides cold bond pellets with a temperature of 0.
By forming a combination of small-diameter particles of 5 to 8 fl,
The inside of the pellet is provided with mesh-like pores through which the reducing gas can flow, and the pellet itself has a size of 1 Ofl or more to ensure ventilation resistance of the packed bed.

Figure 3 shows an example of the manufacturing process of this invention method, in which the part consisting mainly of iron ore is coated with 5 in2° Al 1 o of fine ore.
31 Add auxiliary raw materials mainly consisting of C10, MgO, and a binder such as Portland cement, granulate and mold to form granules of 0.5 to 8 WM [7], and then fill and combine them to form lumps of 8 B or more. (Figure 3A). Also,
The granular material mainly composed of iron ore is made by granulating and molding mainly powdered ore as described above, and if necessary, it is further crushed.
．． For iron ore grains of 5 to 8 fl, iron ore grains of 6, sw or less,
If necessary, add auxiliary raw materials, a binder, and water and selectively granulate it. Use one or more types of granules of 0.5 f1 or more. Al, O,.

Il! mainly composed of CaO and MgO! raw materials, binders,
Alternatively, water is mixed, filled and bonded to the granules mainly composed of iron ore (Fig. 3C, D).

In the method of this invention, the size of the granules before being packed and bonded is limited to a particle size of 0.5 to 8 MII for the following reason.

FIG. 4 shows the results of a softening test under load for each sorted granule.

That is, when the size of the particulate matter exceeds 1O solid, the pressure loss becomes high, but it becomes low when the size of the particulate matter is less than 8fi. This is presumed to be because when the grain size is 8 sided, an oxide layer exists inside, but it does not contribute to the increase in pressure loss due to contraction. In addition, Figures 5 and 6 show the rotational strength and pressure loss for the minimum pellet diameter at the time of mixing, by varying the particle size of small particles of 2H or less and mixing 9 particles size-sized to 5 to gall. In other words, when the minimum diameter is less than or equal to 1, the room temperature strength becomes high and the material becomes usable. Further, the pressure loss in the double softening test was low as shown in Fig. 6, and it was sufficiently usable. That is,
Even if the packed bond collapses during reduction, its minimum unit is 0.
．． 5M, and in this case 0 from Figures 4, 5, and 6.
．． Since it becomes a packed bed of particles of 5 to 8 gw and voids are maintained, it is estimated that the degree of increase in pressure loss is small.

Therefore, in this invention, the size of the granules is set to be 0.5 to 8 square centimeters.

In this invention, the above-mentioned granules having a particle size of 0.5 to 8n are packed and bonded to form a cold bond ore. Therefore, voids formed by particles having a particle size of 0.5 to 8 mm are present in this packed composite. Therefore, reducing gas flows through the voids and reduction occurs throughout the packed assembly. Since the maximum diameter of the granules that make up this packed composite is 6 m or less, most of them are reduced to metallic iron by the time they are put into the blast furnace and heated to around 1300°C, and shrink due to the melting of the Fe0 layer. , no increase in pressure loss occurs. Furthermore, since the granules constituting the packed composite are ordinary cold bond pellets,
Even if the packed composite collapses, the individual granules do not collapse. Therefore, even if the individual granules break apart and the packed composite collapses, the minimum unit is 0.5 mm and a void will remain. This suppresses the increase in ventilation resistance at high temperatures.

As explained above, the cold bond ore produced by the method of the present invention has pores composed of granules having a particle size of 0.5 to 8 sIl.

A high reduction rate can be obtained, and even if it falls apart, its minimum diameter is 0.5 m, ensuring breathability.

Next, embodiments of the invention will be described.

〔Example〕

Shown in Table 1! 1 particle size is LO ~ 8m by mixing 100% of raw materials.
This pellet was mixed with Portland cement and water, filled into a container with a diameter of 100 mm and a height of 100 mm, and a weight was applied from the top of the container to form a cylindrical body. After curing for 7 days, crush and cut into 10-15 m
Table 2 shows the properties of cold bond ore No. 1. Table 2 also shows the properties of cold bond ore, fired pellets, and sintered ore granulated with a pelletizer as conventional examples.

As is clear from Table 2, in the method of this invention, high-temperature properties such as reducibility and pressure loss were good despite the low-grade ore and slightly high slag content.

Table 1 Composition of raw materials used Table 2 Gender Condition

[Brief explanation of drawings]

Figure 1 is a block diagram showing an example of the manufacturing flow of a conventional cold bond pellet, and Figure 2 is a block diagram showing an example of the manufacturing flow of a conventional cold bond pellet. Explanation showing the situation during temperature raising reduction of the bond pellet [, *3ffl is the cold bond pellet Cw of this invention! ! ′! 1. A block diagram showing an example of the flow. Fig. 4 is a chart showing the load softening test results for each grain size of the above pellet. Fig. 5 is a chart showing the relationship between the minimum pellet diameter and cold strength. Fig. 6 is a chart showing the relationship between the minimum pellet diameter and cold strength. It is also a chart showing the relationship between the minimum bellet deviation and pressure loss. Applicant Sumitomo Metal Industries Co., Ltd. Agent Press 1) Yoshihisa', ”, 'i, 'l
'! 3 Diameter 4 f″T! 1 Eye 5 B +3 20 Diameter Tmm 1 Diameter Tmm 1 Figure 6] Voluntary Procedures 1. Indication of Incidents 1982 Special Revision Request 151225 No. 2, Name of the invention Method for manufacturing non-calcined agglomerated ore 3, Relationship with the case of the person making the amendment 1. Detailed explanation of the invention” and “Brief explanation of the drawings” in applicant representative Norifumi Kumagai’s detailed description Column 1, page 6, lines 4 to 5 of the present specification ('Mesh-like pores are provided inside the pellet, and the pellet itself...
・" is corrected as "Mesh-like pores are provided inside the bonded body, and the bonded body itself is...". 2. On page 10 of the same specification, line 3, "There is a slight amount of slag" is corrected to "There is a slight amount of gangue." 3. In Table 2 on page 11 of the same specification, "coke powder" is replaced with "
Corrected as "Coke powder (%)". 4. In the same specification, page 12, line 5, "cold bond pellets" is amended to read "unfired agglomerate."

Claims (1)

[Claims] In a method of producing uncalcined agglomerate ore by adding auxiliary raw materials, a binder and, if necessary, water to powdered ore mainly consisting of iron ore, the particle size of mainly iron ore is 0.5 to 8.
A method for producing uncalcined agglomerate ore, which comprises obtaining granules of M, and further adding rigid raw materials, a solid reducing agent, a binder, or water to the granules if necessary, and filling and bonding them to a predetermined size.