JPH0730417B2 - Manufacturing method of sinter for blast furnace using high goethite ore - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a sinter for a blast furnace using a high goethite ore.

(Prior Art) Sintered ore, which is a main raw material for the blast furnace pig iron manufacturing method, is generally manufactured as follows. First, limestone about 10mm below the iron ore fines, dolomite, containing CaO auxiliary raw material powder such converter slag, silica, containing SiO ₂ auxiliary raw material and coke powder such as serpentine, carbonaceous materials such as anthracite powder, further an appropriate amount of water Add, mix and granulate. Next, the mixed raw material (pseudo-particles) that has been converted into pseudo-particles is placed on a pallet of a moving grate sintering machine for 500 m.
Filled to a height of around m, ignite the carbonaceous material of the surface layer of the packed bed, burn coke while sucking air downward, and sinter the compounded raw material by the combustion heat generated at that time, A sinter cake is produced. This sinter cake is crushed and sized, and particles of 3 to 5 mm or more are filled in a blast furnace as product sinter. Incidentally, a powdered sinter that is not suitable as a blast furnace charging raw material is called a return sinter, and is returned as a raw material for the sinter.

High quality sinter is required for stable and high operation of the blast furnace, and qualities such as cold strength, reducibility, and reduction pulverization resistance are strictly controlled. Further, from the viewpoint of the production cost of the sinter, it is required that the yield (product sinter ore / sinter cake) be high.

The raw material ore of sinter is conventional magnetite (magnetite, Fe ₃ O
₄ ) and hematite (hematite, Fe ₂ O ₃ ) were mainly used, but due to ore circumstances such as the state of high quality iron ore in the world, gradually goethite (F ₂ O ₃ · H ₂ O) The usage ratio of limonite, which contains a large amount, is increasing.

(Problems to be solved by the invention) However, goethite contains bound water as shown in its chemical formula, and in particular, an ore containing a lot of goethite such as bound water / T. (Site ore) causes a decrease in yield and productivity as explained below, as well as the problem that the amount of heat required to remove bound water increases when it is used in a large amount as a sintering raw material. .

The high goethite ore becomes porous because the bound water is decomposed and dehydrated at the temperature around 250 to 500 ℃ during the sintering process, and cracks occur.

In the sintering process, CaO and hematite react with each other when the temperature rises to about 1200 ° C, and a low-viscosity melt is generated. here,
When the iron ore is porous, the melt immediately penetrates into the pores and cracks in the iron ore. At that time, the hematite particles were rapidly separated and partly dissolved in the melt (this phenomenon is called assimilation), and the gas in the pores and cracks was left behind in the melt due to the rapid penetration of the melt. Be done.
Therefore, after these are cooled, the sintered ore has a small amount of binder phase composed of a large amount of granular hematite particles and slag or calcium ferrite, and a large amount of 100 to 1000.
It will consist of micron coarse air holes. The presence of a large amount of granular hematite and a large amount of coarse air holes reduces the resistance to reduction powdering, and the presence of a large amount of coarse air holes reduces the strength and yield. Furthermore, since the assimilation is rapid, the voids in the melt-forming zone in the sintering bed are rapidly blocked, which impairs air permeability (blocking the passage of air) and delays the burning of carbonaceous materials such as coke, which results in production. Sex decreases.

As described above, high goethite ore is dehydrated in the sintering bed and becomes porous, which causes a problem of lowering yield, strength, and reducing properties. Not many. In view of the iron ore situation as described above, the development of effective use of high goethite ore is of great significance.

JP-A-59-197528 discloses that a limonite ore containing a large amount of goethite having a size of 3 mm or more is crushed to adjust the particle size to promote melt generation, and a fragile ore as an original ore Although a method of preventing the residual particles is disclosed, there is a problem that the crushing of coarse particles leads to a decrease in productivity due to a decrease in the particle size of the sintering raw material.

Further, JP-A No. 61-113729 discloses that by using as a sintering raw material a pre-mixed granulated product in which components are adjusted by adding high FeO ore and preferably high MgO ore to high Al ₂ O ₃ limonite. Although a method for suppressing the formation of secondary hematite containing Al ₂ O ₃ component to improve the reduction pulverization resistance is disclosed,
There is a problem that the preliminary granulation product collapses during mixing / granulation of the preliminary granulation product with other raw materials, and the preliminary granulation effect is weakened.

Furthermore, the inventors previously found that when high goethite ore is kept at a high temperature of 1200 ° C. or higher, it is densified by recrystallization of the goethite part, and the ore is removed from the system before the production of sinter. Invented a method of heat treatment (Japanese Patent Application No. 1-14
No. 2808). Although this method can reliably densify high goethite ore, it has a problem that it requires special equipment and a large site.

As described above, conventionally, it was technically and economically difficult to produce a sintered ore having high reduction powdering resistance from a high goethite ore with a good yield. Considering the future ore circumstances, the establishment of a relatively inexpensive effective use of high goethite ore is an important issue, the present invention, when using high goethite ore as a raw material for sinter for blast furnace, Provided is a sinter production method capable of producing a sinter having high resistance to reduction pulverization with good yield.

(Means for Solving the Problems) The present invention relates to a method for producing a sinter for a blast furnace, which uses high goethite ore as a part of a raw material, and a part or the whole amount of high goethite ore powder is used as it is as a solid fuel powder. And then granulate, or classify into coarse and fine grain parts, then mix and granulate the coarse grain part and solid fuel powder, and use this granulation raw material as the upper or lower layer in the sintering bed. It is a method for producing a sintered ore for a blast furnace using high goethite ore, which is characterized by encapsulating or unevenly distributing it in a part of the sintering bed.

(Operation) The process leading to the present invention will be described in detail below.

If the high goethite ore is densified before the melt is formed, the intrusion of the melt into the iron ore can be prevented, and it becomes possible to suppress the formation of a sintered body containing many coarse air holes, which is a problem. Goethite ore can be used in the same way as ordinary hematite ore. As for concrete means for densification, for example, Japanese Patent Application No. 1-142808 describes that high goethite ore is 1200
It is advisable to heat-treat at a temperature T equal to or higher than 0 ° C. for a time t determined by the following formula, and then use as a sintering raw material.

When 1200 ≤ T ≤ 1400 t ≥ 5-0.023 (T-1200) (min) ... When 1400 <T t ≥ 0.4 (min) ... However, T: heating temperature (° C) The maximum temperature in the sintering bed is Generally, 1250 to 1400 ° C is used. Although this is the temperature at which densification occurs, as described above, in the normal chemical composition, as soon as the temperature reaches 1200 ° C, a melt is generated and penetrates into the iron ore, so the time required for densification is secured. I can't. Therefore, it is necessary to heat and densify in the absence of melt. The most reliable method is to process it outside the sintering process,
Japanese Patent Application No. 1-142808 discloses a rotary kiln, a shaft furnace, and a fluidized bed as an example of a heating device. However, as described above, this method requires a dedicated heating device and a vast site, and is difficult to adopt. Therefore,
In the present invention, it was considered to utilize the sintering machine itself as a heating device. That is, high goethite ore is densified by heating it under conditions where almost no melt is formed,
Large particles of mm or more are used as they are as blast furnace raw material,
The smaller-grained portion is used as a raw material for re-sintering again as a sintering raw material.

Conventionally, 5-10 mm of raw iron ore is replaced with bedding sinter particles of the sintering bed, and the raw iron ore is heated and dehydrated by the high temperature combustion gas flowing from the upper layer and reused as return ore. Methods are being studied (Materials and Processes, Vol.1 (1988), 10
47,1048). Therefore, first, the high goethite ore particles are placed in a sintering pot so that a bedding of 5 cm is placed, and then the usual compounded raw materials are placed on the bedding to perform sintering, and the The temperature distribution and the porosity of the particles after heating were measured. Since the bedding did not contain fuel, the temperature was only 1200 ° C or higher in the 1 cm top layer of the bedding, and did not rise above 1300 ° C. Moreover, the holding time above 1200 ℃ is 1 to 1.5m
It was in and did not satisfy the above formula. Further, it was confirmed that the densification was difficult from the porosity ratio measured by mercury porosimetry or the ratio of +20 μm pores and cracks in the cross section (see C = 0% in FIG. 1).

Next, high goethite ore particles were mixed with coke powder in advance, granulated, and charged to a thickness of 10 cm each directly above the normal bedding layer or on the surface layer of the sintered bed. Ordinary sinter ore raw material is enclosed in a height of 40 cm and fired, and high goethite ore material is collected from the sintered sinter cake, and the porosity and crushing strength of 2-3 mm particles are measured and densified. I researched whether I could do it. At this time, 3m
Particles larger than m were crushed to adjust the particle size. The results are shown in Fig. 1. Although the degree of densification differs depending on the encapsulation position of the high goethite ore particles, it was confirmed that the densification was made according to the carbon concentration in the blended raw material. In particular, if the C concentration is 1% or more, the densification is surely made, which is desirable.

Next, regarding the effect of the above densification of high goethite ore on the sintering operation, a continuous dwightroid sintering machine capable of two-stage charging was used to heat-treat -5 m of high goethite ore particles.
It was confirmed by the method of utilizing m as a part of return ore. High goethite ore raw material was charged in the upper layer (Table 1). The results are shown in FIG. The high goethite ore was the same as in Fig. 1, and +5 mm was included in 8%. In particular, it is clear that the production rate (sintering time), the yield, the cold strength and the resistance to reduction pulverization are improved when the ore is densified with C1% or more (see FIG. 1).

The present invention has been achieved through the above process. It can be said that in the present invention, in addition to the effect of densification, the calorimetric effect of eliminating the bound water derived from the high goethite ore, which was originally added to the blending raw material, was added. In addition to coke, the solid fuel powder may be any powder as long as it contains particles such as anthracite and blast furnace gas ash that generate heat by burning with air. In addition, some of the high goethite ore particles also formed bonds.

Furthermore, the “structure mainly composed of granular hematite and coarse air holes”, which is the main cause of yield and quality deterioration of sinter, is related to the grain size of iron ore, and the problem is that the coarse grain side, which becomes the core particle in the pseudo grain, is the problem. Form the structure of. This is because, as already known, a melt is formed all at once in the pseudo-particle-adhered powder layer composed of fine powder, and the melt penetrates into the ore of the core particles. Therefore, if the high goethite ore is sieved and only the coarse grain portion is heat-treated, the treatment amount is small and a great effect can be obtained. The coarse particles having a particle diameter of 1 mm or more, which are generally known to become core particles, may be heat-treated.

The above-mentioned various problems occur because the bound water of the high goethite ore is removed during the sintering process, and when it becomes porous particles, the raw material containing CaO is present around it. The present invention solves the problem by firing a high goethite ore in a state where it is separated from a raw material containing CaO to densify it and using it as a raw material for sintering.

That is, the high goethite ore is made to coexist with the solid fuel and is enclosed in the upper layer or the lower layer in the sintering bed, or is charged so as to be unevenly distributed in a part of the sintering bed. A specific example of the uneven distribution state is shown in FIG. There are several means for realizing these uneven distribution states, as shown in FIGS.

In FIG. 4, high goethite ore powder 1 and solid fuel powder 2 are mixed and granulated by a granulator 12 while adding water, and 2 granulation raw materials 7 composed of high goethite ore powder and solid fuel powder 2 are mixed. One of the base charging devices 16 (two-stage charging method) is used to charge the upper or lower layer in the bed to obtain the state of FIG. 3 (a) or (b). Here, from the viewpoint of reducing the solid fuel powder, it is desirable to charge the granulation raw material into the lower layer. Further, in FIG. 3 (b), the bedding is placed on the bedding C, but the bedding C is for protecting the great bar, and the bedding is not necessary when the heat resistant temperature of the great bar is high. Become. It is the same as before that small grains after crushing sinter cake are also returned.

In Fig. 5, the granulation raw material 7 composed of high goethite ore powder and solid fuel powder is mainly composed of, for example, 5 mm or more (about 80% or more).
The granulation raw material 7 composed of the high goethite ore powder and the solid fuel powder is loaded into the sintering machine hopper 14 by the belt conveyor 10 together with the pseudo particles 8 of other raw materials. Insert, then charging device with classification function 16
Coarse grains are unevenly distributed in the lower layer of the bed through (slit bar type, sizing / dispersion type, etc.). Most of the usual raw materials are 5m
Since it is m or less, the uneven distribution of FIG. 3 (b) is possible.
Here, the granulation raw material discharged from the granulator 12 is sieved to a predetermined particle size by a classifier 13, fine particles are returned to the granulator 12, and only coarse particles are sent to the sintering machine hopper 14. A big effect close to the case can be obtained.

In FIG. 6, a simple hopper 15 is received before or after the normal sintering machine hopper 14, and a classifier 13a is installed in front of the hoppers 14 and 15 to perform simple two-stage charging.
If the simple hopper 15 is installed in front of the hopper 14, the granulation raw material 7 composed of high goethite ore and solid fuel powder is in the lower layer,
If it is installed later, it can be made to exist in the upper layer. Also here, if the granulating raw material 7 discharged from the granulator 12 is classified in advance, the effect is increased.

In Fig. 7, the granulation raw material 7 composed of high goethite ore and solid fuel powder and the pseudo particles 8 of other raw materials are intermittently alternated (left 10 in the figure) or continuously layered on the integrated belt conveyor. Place (right 10a in the figure), send the two kinds of pseudo particles to the sintering machine hopper 14 so that they are not mixed as much as possible, and load them into the sintering machine. As a result, the uneven distribution shown in FIG. 3 (c) is formed.

In addition, the high goethite ore is classified into 1 to 3 mm or more and below in advance by each means, and only the coarse particles are granulated by the granulator 12 or the mixer
When the solid fuel powder is charged in No. 11 as described above, the amount of granulation treatment is small and the same or more effects as when granulating the whole amount can be obtained.

(Example) In the following examples, the high goethite ore used the brand shown in Table 2. The mass ratio of iron ore other than high goethite ore is as follows: Australian hematite ore (gangue; clay system, SiO ₂ =
4.5%): Dense hematite ore (gangue; quartz, SiO ₂ = 5.2%) from South America = 1: 1 to match conventional raw materials in Japan. In addition, the composition of the product sinter was adjusted with conventional limestone powder and serpentine powder so that SiO ₂ = 5.4% and CaO / SiO ₂ = 1.98. The average particle size of solid fuel is generally 1.1-1.3 mm. The new raw materials here mean those excluding returned ore and coke. Furthermore, the conventional method refers to a normal process of uniformly mixing and granulating all raw materials.

Example 1 When high goethite ore is allowed to exist as solid fuel and solid fuel as shown in Fig. 3 (b) with the C% derived from the solid fuel in the blended raw materials being constant, the yield, production rate, and reduction pulverization resistance are significantly improved. It was
In addition, when only the coarse grains of high goethite ore were made to coexist with solid fuel, the production rate was higher than when all the high goethite ore was made to coexist with solid fuel.

Example 2 Even if the proportion of solid fuel mixed with high goethite ore was reduced from the proportion of solid fuel in all the conventional raw materials, the yield, production rate and reduction pulverization resistance could be improved compared with the conventional method. Further, even if the high goethite ore raw material was allowed to exist as shown in FIG. 3 (a), a great effect was obtained as in the case of FIG. 3 (b).

Example 3 As shown in Fig. 3 (b), the effect is slightly smaller than when the granulation raw material is properly contained in the lower layer, but the yield, production rate, and reduction pulverization resistance are clear compared to the conventional method. Was improved.

Example 4 Also in FIG. 6, the improvement in the yield, the production rate, and the resistance to reduction powdering was clear.

Example 5 Even with the simple segregation method as shown in FIG. 7, the effect clearly appeared. Especially, the effect of improving the production rate and the resistance to reduction powdering was remarkable.

(Effects of the Invention) According to the present invention, high goethite ore, which has been difficult to effectively use as a sintering raw material in the related art, is utilized to yield a sintered ore having good reduction powdering resistance with high yield. It becomes possible to manufacture with productivity.

[Brief description of drawings]

Fig. 1 shows the porosity of the high goethite ore after mixing the high goethite ore with powder coke, granulating and sintering, and Fig. 2 shows the C concentration in the raw high goethite ore layer, that is, the density. Fig. 3 is a diagram showing the effects of sintering on the sintering yield, production rate, shutter strength (SI), and reduction powderability (RDI). Fig. 3 shows high goethite ore coexisting with solid fuel on a sintering bed. FIG. 4 is a diagram showing a state in which a portion is unevenly distributed, and FIGS. 4 to 7 are diagrams showing means for embodying the uneven distribution shown in FIG. A: Granulation raw material consisting of high goethite ore powder and solid fuel powder, B ... Other raw materials, C ... Floor covering, D ... Great bar, 1 ... High goethite ore powder, 2 ... Solid fuel powder, 3
...... iron ore, 4 ...... containing CaO auxiliary raw material, 5 ...... containing SiO ₂ auxiliary material, 6 ...... return ores, granulated material consisting of 7 ...... high goethite ore powder and solid fuel powder, 8 ...... Pseudo particles of other raw materials, 9 ... Bedding, 10, 10a ... Belt conveyor, 11 ...
… Mixer, 12, 12a …… Granulator, 13, 13a …… Classifier, 14
…… Sintering machine hopper, 15 …… Simple hopper, 16 …… Charging device.

Claims (2)

[Claims] 1. A method for producing a sinter for a blast furnace, which comprises using high goethite ore as a part of a raw material, a part or all of the high goethite ore powder is mixed with solid fuel powder in advance and granulated, This granulation raw material is charged into the upper layer or the lower layer in the sintering bed, or is unevenly distributed in a part of the sintering bed and is fired. Manufacturing method. 2. In a method for producing a sinter for a blast furnace, which uses high goethite ore as a part of a raw material, a part or all of the high goethite ore powder is first classified into a coarse grain part and a fine grain part. Next, the coarse-grained portion and the solid fuel powder are mixed and granulated, and the granulated raw material is enclosed in the upper layer or the lower layer in the sintering bed, or unevenly distributed in a part of the sintering bed and fired. A method for producing a sinter for a blast furnace, which uses high goethite ore.