JP2589633B2 - Pre-treatment method of sinter ore raw material for blast furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretreatment of a sinter raw material for a blast furnace using high goethite ore.

[0002]

2. Description of the Related Art Sinter, which is a main raw material for blast furnace iron making,
It is generally manufactured as follows. First limestone about 10mm below the iron ore fines, dolomite, containing CaO-based raw materials such as converter slag, silica, containing SiO _2, such as serpentinite
Auxiliary raw materials such as raw materials and solid fuels such as coke breeze and anthracite, and an appropriate amount of water are added, and mixed and granulated by a granulator such as a drum mixer to form pseudo-particles (multiple particles are bonded to each other) Or particles having an average particle size of about 2 to 3 mm in which coarse particles are coated with fine powder.
I do.

[0003] Next, the quasi-particled raw material is filled on a grate-moving sintering pallet to a height of about 500 mm, the solid fuel on the surface of the packed bed is ignited, and air is directed downward. The coke is burned while being sucked, and the raw material is sintered by the combustion heat generated at that time to produce a sintered cake. This sintered cake is crushed and sized to obtain particles of 3 mm or more.

The iron ore is conventionally made of magnetite (magnetite, Fe ₃ O ₄ ) and hematite (hematite, Fe ₂ O ₃ ).
However, the use ratio of iron ore containing a large amount of goethite (Fe ₂ O ₃ .H ₂ O), which was often shunned by ore circumstances such as the state of good iron ore Increasingly.

However, goethite contains a large amount of water of crystallization. Ores containing a large amount of goethite such as Fe ≧ 0.03 (high-gaesite ores) are dehydrated in a sintering bed to be porous, causing a problem of lowering yield, strength, and reducing properties. That is, when the high goethite ore is heated to about 250 to 500 ° C. on the sintering pallet, the crystallization water is decomposed and dehydrated and cracks are generated, and the ore becomes porous.

On the other hand, CaO and hematite react at approximately 1,200 ° C. in the sintering process to form a low-viscosity melt.
Here, the melt immediately penetrates into the pores and cracks of the high goethite ore that has become porous. Due to this infiltration, the hematite particles are rapidly separated, and a part of them is dissolved in the melt to cause an assimilation reaction.

[0007] Further, since the infiltration of the melt is fast, gas existing in the pores and cracks is left behind in the melt. The sintered ore cooled in this state is composed of a large amount of particulate hematite particles and a large amount of coarse pores of 100 to 1,000 μm. Due to the presence of the large amount of granular hematite and the large amount of coarse pores, resistance to reduction powdering is reduced, and strength and yield are reduced. Further, since the assimilation with the melt generated during sintering is fast, the gap in the melt generation zone in the sintering bed is rapidly closed, and the combustion of solid fuel such as coke is delayed, and the productivity is reduced.

[0008] Such a problem often occurs in coarse grains (2 mm or more) where cracks are frequently generated in the sintering process, even in high goethite ores.

Due to the above problems, the use of high goethite ore is increasing, but not so much. However, in view of the iron ore situation as described above, the development of effective use of high goethite ore is significant, and attempts have been made to use large amounts of this high goethite ore.

As this method, for example, Japanese Patent Application Laid-Open No. Hei 1-191
There is a proposal of Japanese Patent Publication No. 750. In this method, coarse high-gaesite ore and serpentine powder are mixed and granulated with a drum mixer, and the periphery of this high-goesite ore is covered with serpentine to form a granule of 6 m in diameter.
m is mixed with the above-mentioned conventional sintering raw material and granulated with a mixer to obtain a sintering raw material. SiO ₂
It is intended to suppress the fluidity of the melt by reacting with the system raw material and prevent assimilation with high-gaesite ore.

In recent sintering machines, fine particles are charged into the upper layer and coarse particles are charged into the lower layer in order to strengthen the segregation of the heat source on the upper layer of the sintering raw material on the sintering pallet. Has been done.

[0012]

However, Japanese Patent Laid-Open No. 1-19 / 1990
No. 1750 discloses coating the periphery of high-gaesite ore of granulated material in order to granulate the granulated material of high-goesite ore and serpentine again together with the conventionally used sintering raw material. As a result, a part of the serpentine is peeled off and the serpentine is mixed into the conventionally used sinter material, so that a sufficient effect cannot be exhibited.

Further, since the granulated material is 6 to 7 mm, which is coarser than other sintering raw materials, when it is segregated and charged as described above, it is charged into the lower layer on the sintering bed. For this reason, the CaO-based raw material having a small particle size is small, the melt is insufficient, and the bonding state between the surrounding structure and the granulated material is weakened, and the yield of the sintered ore is reduced.

According to the present invention, the coating layer of the granules is charged into a sintering bed without peeling off, and the high-gaesite ore granules below the sintering pallet and the granules and the superstructure are combined. A large amount of high-gaesite ore mainly composed of 2 mm or more is used without reducing the sinter productivity, yield, strength, and reduction properties by reducing the sinter productivity, yield, strength, and reduction properties by reacting and combining. The present invention provides a method for pre-treating a sinter material that can be performed.

[0015]

The gist of the present invention is to provide a quasi-granulated material obtained by mixing and granulating iron ore, an auxiliary material, and a solid fuel with a first mixer and quasi-granulating to an average particle size of 2 to 3 mm. The high-gaesite ore produced and mainly having a particle size of 2 mm or more and the fine-grained material mainly having a particle size of 1 mm or less are introduced into a second mixer for granulation provided separately from the first mixer, and water is produced. In the pretreatment method of the blast furnace sinter material for adding and granulating, and supplying the granulated material and the pseudo-granulated material to a sintering machine, the fine-grained raw material to be introduced into the second mixer for granulation is used. 20 to 60% by weight, 40 to 80% by weight of high-gaesite ore having a particle size of 2 mm or more, and 8
To 14% by weight, and MgO
-SiO ₂ based material, CaO-based material, a hematite-containing ore mainly, moreover, the hematite-containing ore with 15 to 85 wt% of the CaO-based material, and the basicity 0.4
1.4, and 5 to 60 granules from the second mixer.
% By weight, 40-95 pseudo-granules from the first mixer
This is a pretreatment method for a sinter material for a blast furnace, which is supplied to a sintering machine in a weight%. As the fine-grained raw material, it is preferable that 16 wt% or less of a solid fuel mainly composed of 1 mm or less be blended in addition to the above-mentioned raw material, and the high goethite ore be 2 to 10 mm. The particle size in the present invention is measured by the standard sieving method of JISZ8801.

[0016]

In order to solve the above-mentioned problems, the present inventors have conducted various experiments and studies, and as a result, it has been found that high-gaesite ores of 2 mm or more can be converted to MgO-SiO ₂ -based raw materials of 1 mm or less (serpentine,
There are many clay minerals such as olivine and talc, but the effect of improving granulation and sintering did not vary greatly depending on the raw material brand, so the example of serpentine with the highest yield will be described below.)
And fine particles mainly composed of CaO-based raw material (hereinafter described as an example of limestone) and ore containing hematite (such as hematite and high goethite ore, and hereinafter described as high goethite ore powder) If the coating layer thickness of the granulated material is 400 μm or more in the sintering bed, productivity of the sinter, yield,
The same level of productivity, yield, strength, and reduction properties as conventional sinter can be secured without reducing strength and reduction properties.
The strength of a granulated material having a particle diameter of about 6 mm obtained by granulating and coating the periphery of a high-gaesite ore having a size of 2 mm or more with the fine-grained raw material was reduced by using a small I-type drum (SGP-5B of JIS 3452) in an amount of 300 g. After loading and rotating at 20 rpm for 2 minutes 3
If the ratio of at least 95 mm is 95% or more, the high goethite ore is transferred to a sintering machine on a belt conveyor together with other sintering raw materials while being granulated and coated with the fine raw materials. It has been found that the separation of the fine-grained raw material due to the drop impact at the connecting portion and the like is reduced, and that the material can be efficiently transported.

The present invention has been made based on these findings. The gist of the present invention is that iron ore, auxiliary materials, and solid fuel are mixed and granulated in a first mixer to have an average particle size of 2 to 3 m.
m and a grain size of 2 m
The high-gaesite ore mainly composed of m or more and the fine-grained raw material mainly composed of 1 mm or less in diameter are introduced into a second mixer for granulation provided separately from the first mixer, and water is added to granulate. In the pretreatment method of the sinter ore raw material for a blast furnace, which supplies the granulated material and the pseudo-granulated material to a sintering machine, the fine-grained raw material to be introduced into the second mixer for granulation is 20 to 60% by weight. The high goethite ore mainly composed of 2 mm or more
To 80% by weight and water to 8 to 14% by weight, and MgO—SiO ₂ based material, C
aO-based raw material, mainly hematite-containing ore, and
The hematite-containing ore is 15 to 85% by weight of the CaO-based raw material, has a basicity of 0.4 to 1.4, and has a second basicity.
A granulated material from a mixer, 5 to 60% by weight, and a pseudo-granulated material from the first mixer, 40 to 95% by weight, which are supplied to a sintering machine. is there.

The first and second mixers may be drum mixers or bread pellets generally used in the sintering process.

According to the present invention, among high-gaesite ores, a large number of cracks are generated during the sintering process in the sintering process, and a coarse-grained portion of 2 mm or more serving as a nucleus during granulation, and serpentine, limestone, or high-gaesite of 1 mm or less The fine-grained raw material of the ore powder is introduced into the second mixer (to be described below with reference to an example of a drum mixer) at the above-described mixing ratio and granulated, whereby the coarse-grained high goethite ore of 2 mm or more is mixed with the fine-grained raw material. This is to make a coated granule. At this time, if the particle size of the fine-grained raw material is more than 1 mm,
Since the adhesion to the high-gaesite ore surface of 2 mm or more is deteriorated and the yield of granules having a layer thickness of 400 μm or more is greatly reduced, the particle size is set to 1 mm or less.

Further, the coarse goethite ore in the coarse portion is 2 mm
If it is less than 50%, the effect of granulating the high goethite ore will be lost since the high goethite ore does not crack during the sintering process.

By adjusting the water content (measured value according to JIS M 8105) to 8 to 14% by weight (hereinafter referred to as%), preferably 9 to 12%, based on the weight of the coated granulated product, The coating granulation of coarse-grained high goethite ore of 2 mm or more by the granular raw material is favorably promoted, and the coating layer thickness of the fine-grained raw material is formed at the outlet of the second drum mixer to 900 μm or more, as shown in FIG. The above-mentioned I-type strength of the granulated product is 9
Increase to 5% or more.

As a result, as shown in FIG. 3, even if the raw material is combined with another quasi-granulated sinter material and charged on a sintering bed via a surge hopper by connecting a conveyor belt, as shown in FIG. The effect can be ensured by maintaining the coating layer thickness of 400 μm or more.

That is, the fine-grained raw material adheres to the surface of the coarse-grained high goethite ore having a water content (amount of water brought into the second drum mixer plus the amount of water added in the second drum mixer) of 2 mm or more. When the water content is 8% or less, the water content of the binder is insufficient, and the fine-grained raw material hardly adheres to the surface of the coarse-grained high-gaesite ore. Becomes thinner. Furthermore, the adhesive force of the fine-grained raw material coating layer is weak, and its strength is also weak,
While being conveyed to the sintering machine by the belt conveyor, it is easily damaged or peeled off by an impact at a connecting portion or the like.

On the other hand, if the water content is 14% or more, the water content becomes excessive and the fine-grained raw material becomes a slurry, which makes it difficult for the fine-grained raw material to adhere to the surface of the high goethite ore. Even if it adheres, it is very soft and weak in strength.

When the fine-grained raw material is set to 20% or less in a mixing ratio of the high-gaesite ore of 2 mm or more and the fine-grained raw material, the high-goesite ore of 2 mm or more serving as a nucleus when granulated by the second drum mixer is used. On the other hand, the fine-grained raw material is insufficient, and it is difficult to secure a fine-grained raw material coating layer (900 μm or more) required for the sintering, and the following effects of the fine-grained raw material coating cannot be sufficiently obtained.

On the other hand, if the content is 60% or more, the fine-grained raw material increases with respect to the high-gaesite ore of 2 mm or more, and the fine-grained raw material coating layer becomes excessively thick, or the granulated material containing only the fine-grained raw material becomes too fine. As a result, the granulation yield centered on coarse-grained high-gaesite ore of 2 mm or more is deteriorated, which is disadvantageous in cost.

Next, the fine grain raw material will be described. Serpentine and limestone are blended so that the basicity in the fine-grained raw material is 0.4 to 1.4, and sintering is performed by blending 15 to 85% of limestone with high-gaesite ore powder of 1 mm or less. The limestone and the high goethite ore powder react by heating in the machine to generate a melt containing a large amount of calcium ferrite. Then, the fluidity of the melt is reduced by the serpentine. As a result, in the lower layer of the sintering machine, the granules are easily fused with each other or with the surrounding ordinary sinter. On the other hand, since the melt has poor fluidity as described above, it hardly penetrates into the pores and cracks of the coarse-grained high goethite ore that is the granulation nucleus. This makes it possible to produce high-strength and large-grain sintered ore.

Assuming that the fine-grained raw material is 100%, the mixing ratio of each fine-grained raw material is as follows: serpentine: 75 to 35%, limestone:
45-22%, fine-grained high goethite ore powder: 30-3% is preferred.

That is, when the serpentinite content is less than 35%, the effect of suppressing the fluidity of the calcium ferrite melt produced by the reaction between the fine-grained high-gaesite ore powder having a particle size of at least 2 mm and limestone as described above is obtained. And the strength after sintering decreases. On the other hand, if the serpentine content exceeds 75%, the flowability of the calcium ferrite melt is almost lost, making it difficult to fuse with other surrounding sintering raw materials, and lowering the sintering yield.

Further, when the content of limestone is less than 22%, the melting point of the fine-grained raw material decreases, and the formation of the calcium ferrite melt becomes too low below the densification temperature of the coarse-grained high-gaesite ore, so that the limestone is formed on the sintering bed. In this process, a calcium ferrite melt is formed earlier than when the coarse-grained high goethite ore is densified. On the other hand, if the content exceeds 45%, the melting point of the fine-grained raw material rises and becomes higher than the densification temperature of the coarse-grained high-geesite ore, contrary to the above. A calcium ferrite melt is produced. Therefore, in any case, the above-mentioned melt cannot be generated during densification of the coarse-grained high goethite ore, and the sintering quality is reduced.

In addition, 30 to 3 of fine-grained high goethite ore powder
% Of the fine-grained high-geesite ore powder and limestone is 15 to
This is a value determined from 85%.

As described above, in the present invention, a fine-grained raw material mainly composed of 1 mm or less and a coarse-grained high-geesite ore composed mainly of 2 mm or more are cut out from separate hoppers and introduced into a drum mixer. However, each raw material cut out from each hopper, that is, serpentine as fine-grained raw material,
All of limestone and fine-grained high goethite ore powder (100%) is 1 mm or less, and all of coarse-grained high goethite ore is 2 m
If it is not less than m, the granulation yield in the second drum mixer will be extremely good, but the equipment cost for sizing (crushing, classification) will increase.

From the above, in the actual operation, the particle size of each raw material in the fine grain portion is 5 mm or less.
mm or less is about 70%, and the grain size of the high goethite ore in the coarse-grained portion is 10 mm or less, and 2 mm or more of the coarse goethite ore is about 80% without significantly reducing the granulation yield. This is preferable because the sizing equipment cost can be reduced.

Further, the mixing ratio of the pseudo-granulated material (normal sintering raw material) from the first drum mixer to 40 to 95% and the coated granulated material from the second drum mixer to 5 to 60% is determined by the coating ratio. When the blending ratio of the granulated product exceeds 60%, the quality of the sintered ore is deteriorated, and this has a bad influence on the blast furnace charged and operated. On the other hand, if it is less than 5%, the amount becomes small and the equipment is not suitable.

Further, in order to sinter the coated granules, crystallization water and water must be scattered and the coating layer must be melted, and a large amount of heat source is required.

From this, 16% or less, preferably 10% or less of solid fuel (coke, anthracite) of 1 mm or less as a heat source in the fine-grained raw material introduced into the second drum mixer.
It is preferable that the solid fuel be contained in the coating layer because the coated granules can be sintered uniformly and efficiently.

However, if the blending ratio of the solid fuel is 16% or more of the amount of the coated granules, the coated granules become excessive in heat on the sintering bed, and a high gap of 2 mm or more as a core of the coated granules is formed. The site ore may be melted, and the effect of coating the high-gaesite ore of 2 mm or more with the fine-grained raw material is lost.

In this case, assuming that the mixing ratio of the solid fuel is X, the mixing ratio of the fine-grained raw material may be such that [1-X] is constituted by the mixing ratio. That is, assuming that the mixing ratio of the solid fuel is X, the serpentinite is [75 × (100−X)] to
[35 × (100-X)]%, limestone is [45 × (10-X)]
0-X)] to [22 × (100-X)]%, and high goethite ore powder is [30 × (100-X)] to [3 × (100
-X)]%.

The reason for setting the mixing ratio is the same as that described above.

When the raw material brand of the fine granules of the coated granules changes, the quality of the sintering raw materials may change. In this case, the ratio of the solid fuel mixed with the pseudo-granules is in the range of 16% or less. In this case, it is preferable to reduce the amount of solid fuel mixed with the pseudo-granulated material by an amount corresponding to the amount of solid fuel mixed with the coated granulated material. Is preferred because it can be produced.

The high goethite ore has a particle size of 10 m.
m or more, the particle size of the coated granulated material coated with the fine-grained raw material increases, and when the granulated material is charged on a sintering pallet, most of the particles are segregated to the lowermost layer. Since the melt source for firing the material tends to be insufficient and the quality of the sinter decreases, the particle size of the high goethite ore is reduced to 1%.
It is preferable to set it to 0 mm or less.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG.

Coarse-grained high goethite ore mainly composed of 2 mm or more (containing 80% or more) serving as granulation nuclei is cut out from the high goethite ore hopper 1a.

Further, as a fine-grained raw material mainly composed of 1 mm or less, 1 m from the MgO—SiO ₂ based raw material hopper 1b is used.
m and 80% or more of serpentine or peridotite, and Ca
Limestone having 70% or more of 1 mm or less from the O-based raw material hopper 1c, and 1 mm from the hematite ore hopper 1d
High goethite ore powder or hematite having 70% or more of the following, and 1 mm or less as fuel from fuel hopper 1e:
Coke flour having 0% or more is cut out separately. Then, the cut-out raw material is passed through a belt conveyor 6a to a second drum mixer for granulation 2 (diameter: 5 m, length: 2
5 m, rotation speed: 6 rpm, residence time: 5 minutes).

The components of the high goethite ore, serpentine, peridotite, hematite and limestone are shown in Table 1, and Tables 2 and 3 show the compounding weight of each raw material on the belt conveyor 6a according to the particle size. It shows the ratio and the basicity in fine-grained raw materials of 1 mm or less.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

In Table 2, Examples I to III of the present invention show that the high goethite ore hopper 1a has a coarser high
-Serpentine from the SiO ₂ material hopper 1b, limestone and hematite ore hopper 1 from the CaO material hopper 1c
This is the case where high goethite ore powder is cut out from d and coke breeze is cut out from the fuel hopper 1e and granulated by the second drum mixer 2.

Inventive Example IV is composed of coarse-grained high-geesite ore from the high-goesite ore hopper 1a, serpentinite from the MgO—SiO ₂ -based hopper 1b, and CaO-based hopper 1c.
Limestone, and coke breeze are cut out from the fuel hopper 1e and granulated by the second drum mixer 2, and high goethite ore powder of 1 mm or less is used as the high goethite ore hopper 1a.
In this case, the fine grains contained in the coarse-grained high-geesite ore obtained from the cutting were used to cover the fine grains.

Inventive Example V is a high goethite ore hopper 1
Coarse high goethite ore containing no less than 2 mm from a
Serpentine not containing more than 1 mm from the gO-SiO ₂ material hopper 1b, limestone not containing more than 1mm from the CaO material hopper 1c, 1m from the hematite ore hopper 1d
m each high goethite ore powder not containing
This is a case where granulation is performed by the second drum mixer 2.

Inventive Example VI is a coarse-grained high goethite ore containing no less than 2 mm from the high goethite ore hopper 1a;
Serpentine, Ca from MgO-SiO ₂ raw material hopper 1b
In this case, limestone is extracted from the O-based raw material hopper 1c, hematite is extracted from the hematite ore hopper 1d, and coke powder is extracted from the fuel hopper 1e, and granulated by the second drum mixer 2.

Inventive Example VII is a coarse-grained high goethite ore from the high goethite ore hopper 1a, and a peridotite and a CaO-based raw hopper 1 from the MgO-SiO ₂ raw hopper 1b.
In this case, limestone is extracted from c, high goethite ore powder is extracted from the hematite ore hopper 1d, and coke breeze is extracted from the fuel hopper 1e and granulated by the second drum mixer 2.

Example VIII of the present invention is a case where the mixing ratio of the coarse-grained high goethite ore is increased. That is, the coarse-grained high goethite ore, MgO-
Serpentinite from SiO ₂ raw material hopper 1b, limestone and hematite ore hopper 1d from CaO raw material hopper 1c
In this case, coke powder is cut out from the higher goethite ore powder and the fuel hopper 1e, and granulated by the second drum mixer 2.

Inventive Example IX is a case where no high goethite ore having a particle size of 10 mm or more is contained at all, and is otherwise the same as Inventive Example IV. This shows that the sinter properties are better than those of Example IV of the present invention.

It should be noted that one or more of the above coarse-grained high goethite ores
mm or less of high goethite ore powder (approx.
(15% or more of limestone of m or less) is used, it is economical because it is not necessary to provide a hematite-containing ore hopper 1d as in Example IV of the present invention.

Further, the second drum mixer for granulation 2
Then, water is added under the conditions shown in Tables 2 and 3 to adjust the total water content of the raw materials, and the raw material is granulated by the drum mixer 2 for granulation.

As described above, both high-gaesite ores of 2 mm or more and 1 mm or less, serpentine, limestone, and coke are granulated by the second drum mixer 2 for granulation, and the high-gaesite ore of 2 mm or more is used as a core. Fine-grained raw materials such as serpentine, high-gaesite ore powder, limestone, and coke of 1 mm or less adhere to the periphery to form granules.

On the other hand, from each of the hoppers 1f to 1i, ore as iron ore, limestone as an auxiliary material, coke breeze as a solid fuel, and further recycle from the hoppers 1f to 1i having the components shown in Table 1 Table 4 shows other raw materials such as ore.
The mixture is cut out at the mixing ratio shown in (1) and charged into the first drum mixer 3 and granulated by adding water to form granules.

[0060]

[Table 4]

The pseudo-granulated matter discharged from the first drum mixer 3 is conveyed to the surge hopper 4 provided on the sintering bed 5 by the belt conveyors 6d and 6e.

In the course of this conveyance, the granules are granulated by the second drum mixer 2 and conveyed by the belt conveyor 6c.
A high goethite ore of at least mm is transported with a granulated material coated with a fine-grained raw material.

Further, the granulated product and the pseudo-granulated product are dropped and mixed when they are charged into the connecting portions of the belt conveyors 6 d and 6 e and the surge hopper 4.

A predetermined amount of granulated material and pseudo-granulated material are cut out from the surge hopper 4 and charged into the sintering bed 5.

The sintering bed 5 immediately below the surge hopper 4
Tables 2 and 3 show the results obtained by sampling the above granulated material and measuring the coating layer thickness, the mixing ratio, the moisture, the basicity, the particle size, and the I-type strength of the coated fine granular material of the granulated material.

As a result of sintering the sintering raw materials on the sintering bed, sintered ores having the properties shown in Tables 2 and 3 could be produced.

As can be seen from Tables 2 and 3, Tables 5 and 6, the inventive examples have better sinter properties than the comparative examples.

[0068]

[Table 5]

[0069]

[Table 6]

In Comparative Example I shown in Table 5, the mixing ratio of the fine-grained raw material mainly composed of 1 mm or less and the high goethite ore mainly composed of 2 mm or more, the mixing weight ratio of the hematite-containing ore and the CaO-based raw material, and the mixing ratio of the coke powder Are examples outside the scope of the present invention.

Comparative Example II is an example in which the compounding weight ratio of the hematite-containing ore to the limestone and the basicity of the fine-grained raw material mainly composed of 1 mm or less are out of the range of the present invention.

Comparative Examples III to V are examples in which the water content of the fine-grained raw material is out of the range of the present invention.

Comparative Examples VI and VIII are examples in which the mixing ratio of the granulated material and the pseudo-granulated sintered ore raw material is out of the range of the present invention.

In Comparative Example VII, the mixing ratio of fine-grained raw material of 1 mm or less to high-gaesite ore of 2 mm or more and 1 m
This is an example in the case where the basicity of the fine-grained raw material mainly composed of m or less is out of the range of the present invention.

It is preferable that limestone and coke supplied to the second drum mixer 2 and the first drum mixer 3 for granulation of this embodiment be classified into respective particle sizes. In order to avoid the high maintenance cost, it is practically acceptable to use the same limestone or coke containing 1 mm or less to avoid this.

[0076]

As described above, according to the present invention, it has been difficult to use a large amount of 2 mm
The above high goethite ore is coated on its surface with an MgO-SiO ₂ -based raw material and a hematite-containing raw material of 1 mm or less, C
aO-based material, coated with fine material consisting of solid fuel, the granules each other, granules and the surrounding is prevented from being merged with CaO-Fe ₂ O ₃ in the sintered material conventional sintering By easily bonding with ore, it can be used in large quantities without deteriorating the productivity, yield and quality of sinter even when segregated on the sintering bed. By combining the coarse-grained high-gaesite ore to be formed with the fine-grained raw material having a predetermined particle size to be formed into the adhering powder, and adjusting the water content to a predetermined range, it can be formed without adding binders such as cement and tar. Since it can be granulated, a great effect is exhibited, such as a great reduction in sinter production cost.

[Brief description of the drawings]

FIG. 1 is a facility flow diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the I-type strength of a serpentine covering layer and the amount of moisture.

FIG. 3 is a diagram showing the relationship between the thickness of a serpentine coating layer and the amount of moisture in a sintering bed.

[Explanation of symbols]

1a High goethite ore hopper 1b MgO-SiO ₂ raw material hopper 1c CaO based raw material hopper 1d Hematite-containing ore hopper 1e Fuel hopper 1f Uniform ore hopper 1g Limestone hopper 1h Powder coke hopper 1i Returning hopper 2 Granulating second drum mixer 3 first drum mixer 4 surge hopper 5 sintering bed 6a-e belt conveyor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiji Ando Oishi, Oita, Oita, Nippon Steel Corporation 1 Nippon Steel Corporation Inside the Oita Works (72) Inventor Tadashi Deno, Oita, Oita, Oita Nishi No. 1 Nippon Steel Corporation Oita Works

Claims (3)

(57) [Claims] An iron ore, an auxiliary material, and a solid fuel are mixed and granulated by a first mixer to produce a pseudo-granulated product in which the average particle size is pseudo-granulated to 2 to 3 mm. The high-geesite ore and the fine-grained raw material having a particle size of 1 mm or less are introduced into a second mixer for granulation provided separately from the first mixer, and water is added thereto to perform granulation. In the method for pre-treating the raw material for a blast furnace, which supplies the raw material and the pseudo-granulated material to a sintering machine, the fine-grain raw material introduced into the second mixer for granulation is 20 to 60% by weight, and the particle size is 2 mm.
High goethite ore 40 to 80 wt% of a main component or, as well as the 8 to 14 wt% water in outer percentage, MgO-SiO ₂ based material as the fine material, CaO-based material, a hematite-containing ores The hematite-containing ore is 15 to 85% by weight of the CaO-based raw material, the basicity is 0.4 to 1.4, and the granulated material from the second mixer is 5 to 60% by weight. Wherein the pseudo-granulated material from the first mixer is supplied to a sintering machine at 40 to 95% by weight. 2. The sinter ore raw material for a blast furnace according to claim 1, wherein 16% by weight or less of a solid fuel mainly composed of 1 mm or less is blended as the fine-grained raw material in addition to the above-mentioned raw material. Pre-processing method. 3. The pretreatment method for a blast furnace sinter material according to claim 1, wherein the high goethite ore has a thickness of 2 to 10 mm.