JP6001485B2 - Method for producing sintered ore for iron making - Google Patents

Description

  The present invention relates to a method for producing a sintered ore for iron making.

Conventionally, not only iron ore mined but also sintered ore obtained by firing powder ore has been used as a blast furnace raw material. Various techniques for producing such sintered ore have been developed as shown in Patent Documents 1 to 7 below.
In Patent Document 1, in a method for producing a sintered ore by sintering a sintered raw material containing various ores and auxiliary materials, 50% or more of the ore to be mixed with the sintered raw material is pisolite ore, and other ores Ore containing 2% or more and less than 5% of SiO ₂ and 3% or more and less than 6% of bound water, and pellet feed or ore containing SiO ₂ of less than 2%. Patent Document 1 discloses a composition as a goethite (Fe ₂ O ₃ · 2H ₂ O), but the composition of goethite is Fe ₂ O ₃ · H ₂ O, which is erroneous. It is.

In Patent Document 2, in a sintered ore production method in which 30 to 50% of iron ore raw material is pisolite ore, 70 to 80% of the whole pisolite ore, iron ore raw material excluding pisolite ore, limestone, serpentine and coke are used. The remaining 20-30% of pisolite ore is mixed and charged into a sintering machine for sintering.
In addition to Patent Documents 1 and 2, there are methods shown in Patent Documents 3 to 5 as methods for producing sintered ore. Although not in the steel field, Patent Documents 6 and 7 disclose techniques for producing color pigments used in cosmetics and paints using iron hydroxide as a raw material.

Japanese Patent Laid-Open No. 10-245638 Japanese Patent Laid-Open No. 08-176688 JP 05-098359 A JP 05-105969 A Japanese Patent Laid-Open No. 04-080327 JP 2005-255500 A Japanese Patent Laid-Open No. 10-204318

Patent Documents 1 and 2 are techniques for producing sintered ore using a raw material having a valence n of 1.0 or less when iron hydroxide is represented by Fe ₂ O ₃ .nH ₂ O. That is, as shown in the techniques of Patent Documents 1 and 2, in the field of producing sintered ore, the idea of producing sintered ore using iron hydroxide having a valence n exceeding 1.0 is There was nothing at all. In addition, even if other patent documents 3-5 are seen, there is no technique which manufactures a sintered ore using the iron hydroxide whose valence n exceeds 1.0 similarly. In addition, although the technique of using iron hydroxide whose valence n exceeds 1.0 is shown in Patent Documents 6 and 7, these techniques are completely different from the technique of manufacturing sintered ore for iron making. Is.

  The present invention has been made in view of the above-mentioned problems, and is an inferior iron ore (iron hydroxide with a valence n exceeding 1.0, in other words, an ultrahigh crystal water-containing ore that could not be used conventionally. It is an object of the present invention to provide a method for producing a sintered ore for iron making that can be used as a raw material for iron making such as a blast furnace.

In order to achieve the above-described object, the present invention takes the following technical means.
The method for producing a sintered ore for iron making using the ultra-high crystal water-containing ore according to the present invention includes Fe ₂ O ₃ .nH ₂ O in which the n of iron exceeds 1.0 and is 4.0 or less, and a CaO source Are mixed so that the molar ratio of CaO / Fe ₂ O ₃ is more than 0.5 and less than 2.0, and the mixed mixture is 2% by mass or more and less than 30% by mass with respect to other sintering raw materials. A sintered ore is produced by sintering the charged material.

  According to the present invention, inferior iron ore (iron hydroxide with a valence n exceeding 1.0, in other words, ultra-high crystal water-containing ore) that could not be used conventionally is used as a raw material for iron making such as a blast furnace. can do.

It is a figure which shows a heat pattern when performing sintering. It is a relationship figure of n of iron hydroxide when a production rate is 2.3-2.5 (t / m < ² > / h), and a yield. It is a related figure of n of iron hydroxide when a production rate is 1.7-1.9 (t / m < ² > / h), and a yield. It is a _CaO-Fe 2 _{O 3} binary phase diagram. It is the figure which showed the combined state of the mixture before and behind sintering (before and after baking), and a sintering raw material. It is a related figure of the compounding quantity and yield of a mixture in case a production rate is 2.3-2.5 (t / m < ² > / h). It is a related figure of the compounding quantity and yield of a mixture in case a production rate is 1.7-1.9 (t / m < ² > / h). It is the figure which put together the relationship of iron hydroxide, a CaO source, a mixture, and other raw materials. It is the figure which showed the relationship between the production rate and the yield regarding a prior art and this invention.

The manufacturing method of the iron ore sintered ore of the present invention will be described.
Conventionally, in a blast furnace, an iron ore (or ore) containing iron ore is introduced from the upper part of the furnace body and hot air is blown from the lower part. Pig iron is produced by a series of reactions such as reduction and dissolution. This blast furnace is a counter-current reactor that continuously performs heat exchange / reduction reactions with the gas ascending in the furnace. For this reason, it is important that the charge to be charged into the blast furnace, particularly the sintered ore, has a dust resistance (strength) that does not impede gas passage in the furnace and good reducibility.

Therefore, in the manufacturing process of sintered ore, calcium ferrite (hereinafter referred to as CF) is synthesized as much as possible, and by forming a connective structure due to the CF-based melt between the particles of the sintering raw material, strength and It becomes possible to produce a sintered ore excellent in reducibility.
In the process upstream of the blast furnace (sintering pretreatment process in the iron making process), for example, a sintered ore is manufactured using a dwelloid-type sintering machine in which a pallet is configured in an endless belt shape.

  In this droite-type sintering machine, when producing sintered ore, first, ore, solid fuel (such as coke powder), pallet moving from the raw material supply side to the product (sintered ore) discharge side, Sintering raw material layers are formed by sequentially supplying and filling sintering raw materials composed of auxiliary materials and others. And by igniting the upper part of the sintering raw material layer and allowing air to pass downward, the combustion proceeds toward the lower part of the sintering raw material layer, and the firing of the sintering raw material is completed before reaching the product discharge side. By doing.

  Here, looking at the sintering process, the sintered raw material charged on the pallet contains solid fuel (coke powder) called a coagulant. When the combustion gas is further sucked by the blower, the frame accompanying the combustion of the solid fuel descends in the sintering material layer, and the sintering material is heated and heated around and below the frame. The part where the frame has already passed is continuously cooled by the gas supplied from above. In the sintering raw material layer, the heat pattern at a certain fixed point from when it is charged on the pallet until it is discharged is as shown in FIG.

On the other hand, the CaO source contained in the sintering raw material is heated and heated during the sintering, and when the temperature exceeds a certain temperature, the synthesis of CF is started by the solid phase reaction between the iron ore and the CaO source, and reaches the melting point of CF. Then, a part of the synthesized CF is eluted as a melt between the particles of the sintering raw material. In the subsequent cooling process, this solidifies to form a connective structure that firmly bonds the sintered raw materials.
Since the connective tissue is formed by solidifying what is eluted as a melt, if the heat pattern is the same, the time during which connective tissue can be formed is the time when the CF that has already been synthesized by solid-phase reaction is used. It is thought to be the time from melting to solidification. Conventionally, an approach and a technique for improving the heat pattern and extending the formation time of a suitable connective tissue have been reported. However, these prior arts involve major modifications of equipment and processes.

In the present invention, iron hydroxide having a structure of Fe ₂ O ₃ .nH ₂ O is used as a part of the sintering raw material, and the synthesis (generation of CF) is performed by mixing this iron hydroxide and a CaO source. ). When sintering is performed using iron hydroxide, the temperature is raised by heating as the sintering raw material layer as shown in FIG. 1 rises, and thermal decomposition starts at around 300 ° C. At this time, iron hydroxide has a specific surface area and a surface shape that is very active. When such a surface-shaped iron hydroxide is mixed with a CaO source, the synthesis of CF by a solid-phase reaction is started at a lower temperature than before.

  That is, even if sintering is performed with the same heat pattern as in the past, by mixing iron hydroxide ore and CaO source as in the present invention and proceeding with sintering, solid phase reaction can be performed from an early stage. CF can be synthesized, and the CF time by solid phase reaction can be lengthened. That is, as shown in FIG. 1, conventionally, for example, CF synthesis was started at arrow B in FIG. 1, but in the present invention, CF synthesis can be started at an early stage of arrow C. .

As a result, when the CF melting start temperature is reached (when entering the section A in FIG. 1), a larger amount of CF-based melt is eluted than before, and a larger amount of CF-based connective tissue is formed during cooling. Can be formed. The section A is an example of a connective tissue formation section (time from elution of CF melt to solidification).
As described above, it is considered that a large amount of CF can be generated by mixing the iron hydroxide of Fe ₂ O ₃ .nH ₂ O and the CaO source to accelerate the synthesis of CF, but promote the synthesis of CF. In order to achieve this, it was considered advantageous to use particles having a large reaction interfacial area and high surface reactivity, and verified what kind of iron hydroxide was suitable.

Iron hydroxide that is Fe ₂ O ₃ .H ₂ O (n = 1) is called goethite, and when this goethite is used, as shown in FIG. 2 and FIG. In addition, it is not possible to use a goethite with a low charge yield and substantially n = 1. Further, it is considered that n = 0 to 1 is composed of n = 1 goethite and Fe ₂ O ₃ (hematite) containing no bound water. Even if it is, the yield of the charge is not improved as in the game site.

  On the other hand, when a hydroxide having n of more than 1 (n> 1) is used for sintering, a large amount of heat is required for decomposition of the bound water in the process of firing, and extra firing energy is required. It has been considered undesirable to use iron hydroxide for sintering. In other words, when iron hydroxide is used as part of the raw material constituting the sintered raw material particles, it is generated in the sintered ore raw material particles due to heat shortage due to the endothermic reaction accompanying the decomposition reaction of bound water and the release of water vapor during decomposition. Due to the cracking, the contact between the particles is insufficient, and further, it becomes difficult for the CaO source for forming CF to be present in the vicinity of the iron hydroxide, and in a solid state in the particles of the sintering raw material. It has been considered that the synthesis of CF does not proceed efficiently, the strength of the connective structure of the sintered ore decreases, and the yield also decreases. For this reason, as a matter of course, it has never been conceived so far to use iron hydroxide, which has a stronger effect of bonding water than when n exceeds 1.0, as a means for bonding sintered raw materials.

However, the inventors have continued to verify iron hydroxide whose n exceeds 1.0 without being caught by the conventional idea. As a result, it was found that when a hydroxide with n exceeding 1 (n> 1) is used for sintering, the yield of the charge can be improved as shown in FIGS. .
It should be noted that iron hydroxide (iron hydroxide or hydroxide ore) is expressed as Fe ₂ O ₃ .nH ₂ O is technical literature: “Steel production method, 3-1 raw material, Table 3.1 iron ore. No. 4, 163, Japan Iron and Steel Institute book, published on April 10, 1972, Maruzen Co., Ltd., and is well known among those skilled in the art. Also, in iron hydroxide, for example, as shown in "Lecture: Modern Metallurgy, Volume 1 Steel Smelting, Japan Metallurgy Society, Issue 1 pp. Pp. 98-99" In addition, it is known that the value of n does not exceed 4 mineralogically. The n of iron hydroxide is a coefficient expressing the amount of compound water, and can be determined by thermal analysis and chemical analysis. Specifically, the valence is the total iron number tFe (JIS M8212 total iron determination method), divalent iron (JIS M8213 divalent iron determination method), FeO and compound water (JIS M8211 compound water determination by chemical analysis). Method) and the amount of CW. The valence n is obtained by n = W / Hm × 2 (however, Hm = tFe / 55.85-FeO / 71.85, W = CW / 18).

In other words, in the present invention, iron hydroxide having n of Fe ₂ O ₃ .nH ₂ O exceeding 1.0 and 4.0 or less is mixed with a CaO source to promote the formation of CF.
Now, the CaO sources mixed with the iron hydroxide described above are quick lime CaO, slaked lime Ca (OH) ₂ , and limestone CaCO ₃ . In mixing the iron hydroxide and the CaO source, any one or more of quick lime, slaked lime, and limestone may be used. Limestone and slaked lime decompose upon heating to produce CaO. Further, quick lime, slaked lime, and limestone may be mixed and used. In producing a sintered ore, JP 2004-315277 A discloses an example in which gypsum is used. However, in this method, it is necessary to remove Ca, which is an impurity, and desulfurization. Since a process is required, it is difficult to use industrially.

In summary, in the sintering pretreatment step, the mixture of Fe ₂ O ₃ .nH ₂ O in which iron hydroxide of n exceeding 1.0 and 4.0 or less and the CaO source are mixed and mixed at the time of sintering. And, this mixture is fired with another sintering raw material different from the mixture.
As described above, CF is synthesized by a solid phase reaction between iron hydroxide and a CaO source during heating and heating. In order to synthesize this CF without excess or deficiency, the CaO- As shown in the Fe ₂ O ₃ binary system phase diagram, the range D including the lower limit temperature of the liquidus may be set. That is, when mixing the iron hydroxide and the CaO source, the molar ratio of CaO to Fe ₂ O ₃ (CaO / Fe ₂ O ₃ ) in the mixture is more than 0.5 and less than 2.0. Just do it.

  FIG. 5 shows the bonding state between the mixture before and after sintering (before and after firing) and the sintering raw material. As shown in FIG. 5A, before sintering, the mixture 1 and another sintered raw material (referred to as other raw material) 2 different from the mixture 1 exist in separate states. As shown in FIG. 5 (a), when sintering proceeds while the mixture 1 enters between the other raw materials 2 and 2 (between particles of the sintered raw material), a large amount of CF ( CF solution) is eluted, and the eluted CF solution is assimilated with the other raw material 2, and after sintering, the other raw materials 2 are bonded to each other by a strong connective structure 3 as shown in FIG.

As described above, in order to firmly bond other raw materials to each other by the CF solution eluted from the mixture, in the present invention, the mixture is charged (mixed) in an amount of 2% by mass to less than 30% by mass with respect to the other raw materials. It is said.
As shown in FIGS. 6 and 7, when the blending amount of the mixture with respect to the other raw materials is less than 2% by mass, a sufficient amount of connective structure cannot be formed in the sintered raw material layer, and the yield is not improved. . In other words, if the mixture of the other raw materials is small, the ratio of the mixture contained between the particles of the other raw materials is small compared to the entire sintered raw material layer. However, the yield could not be improved sufficiently.

  When the blending amount of the mixture with respect to other raw materials is 2% by mass or more, the yield is rapidly improved. As the charging amount of the mixture is gradually increased from 2% by mass, the total amount of CF melt eluted from the mixture increases. Although a certain amount of CF melt acts as a connective structure and contributes to the bonding of other raw materials, the excess CF melt that did not work as a connective structure is located below the sintered raw material layer due to the downward ventilation during sintering. Although it moves, it may solidify in the middle of the sintering raw material layer (for example, in the vicinity of the middle lower layer portion), possibly inhibiting the blower. That is, when the CF melt moving by the downward air flow is excessive, the gas passing through the sintering raw material layer drifts, increasing the generation rate of the so-called non-uniform sintered structure called burn unevenness, and increasing the yield. May decrease.

As shown in FIGS. 6 and 7, when looking at the blending amount of the mixture with respect to the other raw materials and the state of the yield, if the blending amount of the mixture with respect to the other raw materials is more than 2% by mass and less than 30% by mass, the yield is Although improved, the yield decreased when the blending amount of the mixture exceeded 30% by mass.
In summary, as shown in FIG. 8, first, iron hydroxide having n of Fe ₂ O ₃ .nH ₂ O exceeding 1.0 and 4.0 or less is mixed with a CaO source. In mixing the iron hydroxide and the CaO source, the molar ratio of CaO / Fe ₂ O ₃ exceeds 0.5 and is less than 2.0. If the mixed mixture is charged with 2% by mass or more and less than 30% by mass with respect to other sintering raw materials and sintered, the formation of CF can be promoted and the yield of sintered ore can be improved. Can do.

  Tables 1 to 8 summarize the examples sintered by the method for producing a sintered ore for iron making according to the present invention and comparative examples in which sintering was performed by a method different from the present invention.

In Examples and Comparative Examples, sintering was performed using a test sintering machine. This test sintering machine is a sintering pan having a diameter of 300 mm and a height of 350 mm, and this sintering pan is made of steel and has a grading bottom surface so that air can be sucked downward. The component target of the sintering raw material was SiO ₂ : 7.0 mass%, CaO: 18.0 mass%, Al ₂ O ₃ : 1.8 mass%, and the pseudo particle average particle size was about 3 mm. Ore A which is a sintering raw material is Hamasley, and ore B is riodose. In the sintering test, raw materials including a mixture of iron hydroxide and a CaO source (quick lime, slaked lime, limestone), ore A, ore B, limestone, and dolomide are mixed and granulated using water or the like, and sintered for testing. It was inserted into the machine, the surface was ignited by an ignition burner, air was sucked from below and baked. When the flame reached the bottom of the test sintering machine (sintering pan), it was finished and cooled. After sintering, the sintered cake was dropped on the iron plate 4 times from a height of 2 m, and the weight ratio of the sintered ore 5 mm or more after being dropped 4 times was used as the yield. That is, the yield was determined by the mass of sintered ore having a particle size of 5 mm or more / the mass of sintered cake. The production rate was determined by “Production rate = mass of sintered ore having a particle size of 5 mm or more / effective area of the sintering machine / sintering time”.

The sintering time was defined as the time required for the flame to reach the lowest layer from ignition in a test sintering machine.
In the example, the Fe ₂ O ₃ · nH ₂ O has an iron hydroxide and a CaO source in which n exceeds 1.0 and is 4.0 or less, and the molar ratio of CaO / Fe ₂ O ₃ exceeds 0.5. It mixed so that it might become less than 0.0. Moreover, in the Example, 2 mass% or more and less than 30 mass% of the mixture with respect to the other sintering raw material were charged.

On the other hand, in the comparative example, at least one of the valence n of iron hydroxide (Fe ₂ O ₃ .nH ₂ O), the molar ratio of CaO / Fe ₂ O ₃ , and the blending amount of the mixture with respect to other sintering raw materials is It is different from what is prescribed in the invention.
FIG. 9 summarizes the relationship between the production rate and the yield in the related art including the comparative example and the present invention (Example). As shown in FIG. 9, in the present invention, even if the production rate is the same as that of the comparative example and the conventional example (Japanese Patent Laid-Open No. 2011-075122, Japanese Patent Laid-Open No. 2009-209408, Japanese Patent Laid-Open No. 2009-228133). Was able to improve the yield.

That is, according to the present invention, as described above, inferior iron ore that has been considered to be unusable in the past (iron hydroxide with a valence n exceeding 1.0, in other words, ore containing ultra-high crystal water) Was used to improve the yield.
In the embodiment disclosed this time, matters not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, etc. of components deviate from the areas normally practiced by those skilled in the art. However, matters that can be easily assumed by those skilled in the art are employed.

1 Mixture 2 Other raw materials 3 Connective tissue

Claims (1)

4.0 and less iron hydroxide exceed Fe ₂ O ₃ · nH ₂ O n is 1.0, and a CaO source, the molar ratio of CaO / _Fe 2 _{O 3} is less than 2.0 more than 0.5 The mixture is mixed so that the mixture is mixed, and the mixture obtained is sintered by charging the mixture containing 2% by mass or more and less than 30% by mass with respect to other sintering raw materials. A method for producing sintered ore for iron making using ultra high crystal water-containing ore.