JP2009030115A - Method for producing ore raw material for blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing non-fired agglomerated ore as an ore raw material for a blast furnace using sintered powder or straight undersized powder. <P>SOLUTION: In the method for producing an ore raw material for a blast furnace where sintered powder of ≤5 mm generated upon the production of sintered ore is formed without being made into sintering return ore, so as to be agglomerated into non-fired agglomerated ore, and this is used as an ore raw material for a blast furnace, the raw material for forming for obtaining the non-fired agglomerated ore is composed of the one comprising the above sintered powder and iron oxide fine powder, and the raw material for forming is further admixed with a binder, and kneading is performed, and the kneaded matter is subsequently formed, so as to be the non-fired agglomerated ore. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a blast furnace ore raw material, and particularly to a method for producing a blast furnace ore raw material using sintered powder generated during the production of sintered ore.

  In general, sintered ore used as a raw material for blast furnace ores in the iron making process is manufactured by adding secondary raw materials and carbonaceous materials to iron-containing raw materials such as iron ore powder and heating and firing them using a DL-type sintering machine. ing.

  For example, as shown in FIG. 1, a medium solvent such as quick lime and limestone and powdered coke are added to powdered iron ore, mixed with a mixer and then molded (granulated), and then placed on the pallet of the sintering machine. And then fired and fired, and then, through the crushing-cooling-sieving steps, a product sintered ore (fired agglomerated) having a particle size of about 5 to 50 mm is obtained. Supplying into the blast furnace. On the other hand, a sintered ore having a particle size of 5 mm or less, that is, a so-called sintered powder, is returned to the sintering machine as a return ore and fired again. In addition, the product sinter obtained by removing powder of 5 mm or less generated during the transfer process to the blast furnace with a sieve, so-called pre-furnace sieve powder, is also returned to the yard without being charged into the blast furnace. Then, it is refired (re-sintered) as part of the sintered raw material in the same manner as the return ore. That is, these return minerals and pre-furnace pre-sieving powders are once fired through a sintering process, and it is preferable in view of firing costs and transportation costs to recirculate them. It is not a treatment method.

  Therefore, conventionally, agglomeration techniques have been proposed in which briquettes are made using sintered powder that has already been fired, and the briquettes can be directly charged into a blast furnace or the like. For example, Patent Document 1 discloses a method in which 20 to 25 mass% of water and cement are added to a sintered ore and kneaded and then granulated, and then subjected to a hydration curing treatment to form a briquette product. Yes.

Patent Documents 2 and 3 describe the production of non-fired agglomerated minerals that are granulated using a binder in order to use such sintered ore and pre-furnace sieving powder as raw materials for ores for blast furnaces. There is a disclosure about the method.
JP 58-123839 A JP 7-224329 A Japanese Patent Laid-Open No. 7-71824

  Among the above prior arts, the briquetting method described in Patent Document 1 uses Portland cement as a rapid setting agent in order to granulate sintered powder (-5 mm) which has deteriorated wettability and granulation property due to firing. This is a technology that uses a mixture of the slag and agglomerated as a raw material for a blast furnace. However, briquettes produced by this method, when viewed as a blast furnace charging material, crush strength at low and high temperatures, reduced powdering characteristics (JIS-RDI, hereinafter simply referred to as “RDI”), reducibility (JIS) -RI (hereinafter simply referred to as “RI”) was poor, and there was a need for improvement.

  Next, the methods described in Patent Documents 2 and 3 are all techniques for producing unfired agglomerated minerals, and are characterized in that they aim to improve cold strength by devising binders and carbonation curing treatment. However, the agglomerates obtained by these conventional techniques are also insufficient in reducing powdering properties (RDI) and reducing properties (RI), causing reduced powdering in a blast furnace, so There was a problem of causing a drop. Therefore, the agglomerates until now remain uneasy to use as a raw material for blast furnace ore directly without reusing the sintered powder for return mineralization or the pre-furnace sieving powder in a sintering machine.

An object of the present invention is to propose a method that can advantageously produce an unfired agglomerated mineral that is a raw material for blast furnace ore using sintered powder or pre-furnace sieve powder.
Another object of the present invention is to propose a technique capable of reliably producing a non-calcined agglomerate having high crushing strength at normal temperature and high temperature and good reduction powdering properties (RDI) and reducing properties (RI). There is to do.

  Inventors propose the manufacturing method of the blast furnace ore raw material which concerns on the following summary structure as a method effective in the implementation | achievement of the said objective, without the above-mentioned problem which the prior art has. That is, the present invention forms a non-fired agglomerated ore by forming and agglomerating a sintered powder of 5 mm or less generated during the production of the sintered ore without forming it into a sintered ore. In the method of making a blast furnace ore raw material, a forming raw material for obtaining the unfired agglomerated ore is composed of the sintered powder and fine iron oxide, and a binder is further added to the forming raw material. A method for producing an ore raw material for a blast furnace, characterized in that the mixture is kneaded and then formed into an unfired agglomerated ore.

  In the present invention, the molding raw material may further contain pre-furnace sieving powder, or may contain any one or more of dust, sludge, iron ore powder and the like. The fine iron oxide is a Rusner iron oxide powder having a maximum particle size of 10 μm or less and containing 90 mass% or more of iron oxide, mill scale generated in the steel manufacturing process, refining dust, and 3 to 6 mass% contained in the blended raw material It is preferable that the The binder is an inorganic binder and / or an organic binder, the inorganic binder is any one or more selected from blast furnace granulated slag, bentonite and water glass, and the organic binder is molasses or It is a synthetic resin binder, and the synthetic resin binder is preferably a phenol resin binder. The non-calcined agglomerated mineral has an RI (reducing property) of 65% or more, and the non-calcined agglomerated material has an RDI (reducible powdering property) of 30% or less. Provides a more effective solution.

According to the present invention according to the above-described configuration, the sintered ore and the pre-furnace sieve powder that were originally recirculated and refired are immediately agglomerated without being recirculated. Since it can be used directly as an input material, it is possible to achieve a reduction in sintering costs, various basic units, sintering equipment costs, and maintenance costs. In addition, according to this proposed technique, the reduction of the sintered coagulant brings about a ripple effect such as effective use of resources and contribution to environmental protection (CO ₂ reduction).

  Moreover, according to the present invention, in addition to being excellent in compression moldability, non-fired agglomerated minerals with high crushing strength and cold strength (DI) are produced using sintered powder for return ore, pre-furnace sieve powder, etc. as raw materials. can do. Moreover, even when the obtained unfired agglomerated ore is charged into the furnace as a raw material for blast furnace ore, it has excellent reduced powdering characteristics (RDI) and reducibility (RI) at low and high temperatures. This will stabilize the operation of the blast furnace and reduce the cost of pig iron production.

The sintered ore (product) is usually crushed at the pallet end after firing, and the particle size is adjusted to a size of 5 to 50 mm with a vibrating sieve or the like. At this time, the sintered powder (particle size: −5 mm) generated as the sieve of the vibrating sieve is generally returned to the sintering machine, and is again subjected to the sintering process together with new iron ore powder as return ore. It is normal. In order to recycle the sintered powder as a return ore, as described above, it is necessary to review such usage from the viewpoints of an increase in manufacturing cost, transportation cost, and environmental protection (CO ₂ reduction). That is, the difference between return ore (sintered powder) and product sintered ore is simply that the particle size is different. Therefore, if the sintered powder that becomes the sintered ore is formed into the same particle size (> 5 mm) as the product (sintered ore), it should be able to be used as a raw material for ore for blast furnace.

  Under the above-mentioned concept, the present invention re-sinters the -5 mm sintered powder, which becomes a sintered ore, into a size of about 5 to 50 mm, thereby re-sintering it. This is a method of making agglomerates effective as raw materials for blast furnace ore without any changes.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a flow diagram of a process for producing a raw material for blast furnace ore made of unfired agglomerated ore. The example described below is an example of manufacturing briquettes by a molding machine, but it is a matter of course that the same effect can be obtained even when pellets are manufactured using a granulator instead of the molding machine.

  In the present invention, the raw materials for molding to be non-fired agglomerated materials such as sintered powder, pre-furnace pre-sieving powder, and fine powdered iron oxide as main starting materials are stored in compounding tanks 1, 2, and 3, respectively. Then, it is cut out on the conveyor 5 by the quantitative cutting device 4 so as to have a predetermined blending ratio. Next, these forming raw materials are mixed in the first mixer 6 and, if necessary, the second mixer 7. If necessary in this mixing step, humidity adjustment (moisture addition) may be performed.

  Thereafter, the mixed raw material is sent to the raw material tank 8. The raw material tank 8 also stores an organic binder, an inorganic binder, and the like. These binders are mixed with the mixed raw material in a mixer 9 (usually using a hug mill), and here, the humidity is adjusted and kneaded as necessary. Next, the mixed raw material is supplied to the molding machine 11 through the kneader 10 and agglomerated into a predetermined size. The agglomerated ore obtained is discharged through the shaking sieve 12 and carried directly to the blast furnace or on the yard.

  In the production process of the non-fired agglomerated mineral produced as described above, the first feature of the present invention is the kind and blending of the forming raw material that is the starting raw material. That is, the raw materials for molding used in the present invention are mainly sintered powder having a size of 5 mm or less, which is supposed to be sintered and returned, and under-furnace sieve powder (5 mm or less generated in the conveying process of the blast furnace). Sieving powder). In the present invention, as described later, at least fine iron oxide, for example, hematite powder, Rusner iron oxide powder, etc. are added to these forming raw materials, and an organic binder or inorganic binder is added, and then these are mixed with a mixer (mixed) Machine) and then kneaded, and then molded (granulated) in a molding machine or granulator. The particle size distribution and chemical composition of typical sintered powder and pre-furnace sieving powder as molding raw materials are shown below.

  In the present invention, the sintered powder mainly used as a forming raw material is fired compared to an iron ore raw material or the like, and therefore has poor wettability. For example, a blast furnace iron ore raw material (mount Newman or lobe) In the case of River, Sendy), the contact angle with water is 37.0-48.3 deg, whereas the sintered powder is as high as 74.1 deg. The use of an inorganic binder is essential.

In general, this type of uncalcined agglomerate uses cement as a binder, so the following decomposition reaction from several hundred degrees;
Ca (OH) ₂ → CaO + H ₂ O
It is known that the strength decreases sharply. If the hot strength of the unfired agglomerate charged in the blast furnace is low, the non-fired agglomerate is reduced to powder at the shaft portion in the blast furnace, and the air permeability in the furnace is impaired. That is, in the high-temperature reducing atmosphere in the blast furnace, the unfired agglomerated ore is pulverized because of the reaction of Fe ₂ O ₃ → Fe ₃ O ₄ and volume expansion.

  As described above, when the molding raw material is molded using cement as a binder, the strength rapidly decreases at high temperatures. In this regard, it is considered effective to add a substance that develops hot strength to the forming raw material in order to develop strength in the blast furnace.

  FIG. 2 shows a general formula of a solid-phase sintering reaction in the case where the hot strength of particles is expressed. The left side of this equation indicates the amount of shrinkage due to the progress of sintering, and it can be considered that the sintering progressed as the shrinkage amount increased. As shown in this equation, agglomerated particles formed by molding various powders, such as non-fired agglomerates as in the present invention, shrink depending on parameters such as temperature, particle size of particles, and sintering time. Although the amount changes, since the temperature and sintering time are actually determined by the atmosphere in the blast furnace, it cannot be changed. Therefore, in order to increase the hot strength of the particles using the solid phase sintering reaction, it is effective to adjust the particle size of the raw material particles to be blended. In particular, it can be seen that it is effective to use a small particle size (fine powder) in the blended raw material.

  Therefore, in the case of blast furnace ore raw materials, it is effective to use fine (submicron order) molding raw materials in order to develop the hot strength of particles by such solid-phase sintering reaction. it is conceivable that. For example, the use of finely divided iron oxide is considered effective. Then, the inventors paid attention to Rusner iron oxide powder as the finely divided iron oxide, and performed a sinterability evaluation test on the powdered iron oxide added to the raw material for molding. In the evaluation method, the raw material for molding was formed into a tablet shape (tablet) having a size of φ10 × 5 mm, which was fired in both a nitrogen atmosphere and a reducing atmosphere in a blast furnace, and the crushing strength was measured.

FIG. 3 shows the measurement results of the crushing strength after cooling after heat treatment of the tablet fired in a nitrogen atmosphere and in FIG. 4 in a blast furnace reducing atmosphere. Under any atmosphere, it was confirmed that the strength increased in a region of about 600 ° C. or higher corresponding to the thermal decomposition temperature of cement. Note that the same fine powder, that is, OG dust (dust generated from a converter) having a particle size close to that of Rusner iron oxide powder but having a large amount of impurities has a small increase in strength, and MBR having a particle size on the order of several tens of μm. In the ore (pellet feed), the sintering start temperature is very high. All of these have a larger particle size and larger specific surface area or higher impurities and lower cleanliness of the particle surface than Rusner iron oxide powder. Because of the high temperature, the effect as much as Rusner iron oxide powder does not appear.
In this regard, Rusner iron oxide powder with a particle size on the order of submicron and with few impurities starts a solid-phase sintering reaction at a relatively low temperature range of about several hundred degrees, and the hot strength of unfired agglomerated ore. This proves to be a promising substance for expressing

As the finely divided iron oxide used in the present invention, a fine powder consisting essentially of iron oxide containing 90 mass% or more of iron oxide having a particle size of 10 μm or less is suitable. However, a very small amount of substances other than iron oxide (for example, SiO ₂ , Al ₂ O _3, etc.) may be included as part of particles containing iron oxide or included as particles not containing iron oxide. It may be a small amount (≦ 1 mass%). The reason is that when the fine iron oxide is charged into the blast furnace, these impurities affect the slag ratio and slag component design. The iron oxide may be any of Fe ₂ O ₃ (hematite), Fe ₃ O ₄ (magnetite), and FeO (wustite).

Examples of such finely divided iron oxide include the above-described Rusner iron oxide powder, mill cases and refined dust produced in the steel manufacturing process, and one or more of these can be used. Here, Rusner iron oxide powder refers to the pickling sludge generated when the surface iron oxide layer is removed by pickling (pickling with a hydrochloric acid solution) before rolling in a steel material manufacturing process such as a steel plate. It was obtained by treatment by a method such as firing, and Fe ₂ O ₃ : 99.4 to 99.9 mass%, CaO ≦ 0.02 mass%, SiO ₂ ≦ 0.004 mass%, Al ₂ O ₃ ≦ 0. .01 mass%, MgO ≦ 0.002 mass%, etc. It is a high purity and fine powder iron oxide having a particle size of 10 μm or less.

In addition, in the present invention, another reason for blending the fine iron oxide is to develop high temperature strength. That is, according to a place where the inventors conducted a heat treatment test on the granulated product after molding in an N ₂ atmosphere, in the case of the agglomerate containing 3 to 6 mass% of the Lusner iron oxide powder, from about 200 ° C. to 1000 ° C. When the temperature was raised to 1000 ° C., the strength index was 78%, whereas the strength index was 58% without the Lusner iron oxide powder, and the sintering of the Rusner iron oxide powder (solid phase firing). Result of high-temperature strength by If this fine iron oxide powder is less than 3 mass%, the effect of improving the strength is weak, whereas if it exceeds 6 mass%, the effect is saturated.

  Next, the binding material will be described. In the present invention, the sintered powder mainly used as a forming raw material is fired compared to an iron ore raw material or the like, and therefore has poor wettability. For example, a blast furnace iron ore raw material (mount Newman or lobe) In the case of River, Sendy), the contact angle with water is 37.0-48.3 deg, whereas the sintered powder is as high as 74.1 deg. Is essential. In this case, a hydraulic binder such as alumina cement or Portland cement or blast furnace granulated slag is used as a general binder.

  However, hydraulic binders such as cement increase the crushing strength at room temperature, facilitate transfer to the blast furnace, and also help to maintain its shape in the low temperature region at the top of the blast furnace. As described above, in the high temperature region in the middle to the lower part of the blast furnace, the strength of the cement hydrate is reduced due to thermal decomposition, and the pulverization in this region (middle and lower part of the blast furnace) and the accompanying deterioration of the air permeability in the furnace are caused. It is known.

  Therefore, in the present invention, in order to overcome the problems of hydraulic binders such as cement described above, inorganic binders and organic binders such as bentonite and water glass such as tar, pitch, molasses or synthetic resin binders are used. One or more were decided to use as a binder. In the present invention, it is preferable to use a phenol resin, especially the synthetic resin binder.

  The phenol resin which is the synthetic resin binder is characterized in that it functions as a binder at normal temperature and carbon generated by carbonization in a high temperature region in the blast furnace functions as a binder. In addition, the phenol resin which exists as a binder in the non-baking agglomerated mineral of the present invention is a resin obtained by thermosetting a phenol resin precursor.

  By using the above-mentioned phenol resin, which is a synthetic resin binder, as a binder for forming raw materials such as sintered powder and pre-sieving powder, non-fired agglomerated ore is hardened phenol at room temperature at the time of molding. Crushing strength of 390N / piece can be secured by the binder function of the resin itself and the moldability is improved. At the time of use, carbon generated by carbonization of the phenolic resin in the high temperature range of the blast furnace exhibits the binder function, so at least 1000 ° C. The crushing strength of 100 N / piece or more can be secured in the temperature range up to. Therefore, it can be said that the non-calcined agglomerate formed using such a binder is less pulverized in the yard, in front of the blast furnace and in the furnace, and exhibits excellent characteristics as a blast furnace ore raw material.

  In particular, the phenol resin that enters the blast furnace as part of the constituents of the unfired agglomerated minerals is decomposed by heat and partly gasified, and carbon (pyrolysis residue) is generated in the unfired agglomerated minerals. . That is, the phenol resin has a carbon ratio (residual carbon ratio) remaining when heated to 500 ° C. or higher in a non-oxidizing atmosphere, which is about 40% by mass or more, compared with almost 0% of many resins such as acrylic and polyolefin. The high point is a characteristic binder. Therefore, the non-fired agglomerated agglomerate obtained by agglomerating phenol resin as a binder maintains the crushing strength by the binder function of the phenol resin itself from the time of charging the blast furnace to about 350 ° C. In order to develop the hot crushing strength of the unfired agglomerated minerals, the carbon produced by carbonization of the phenolic resin functions as a binder in the high temperature range. Become.

  Further, in the production of the non-fired agglomerated mineral of the present invention, as described above, it contains a raw material for molding such as sintered powder, finely divided iron oxide and a binder as main components, but if necessary, other components For example, one or more of iron ore powder, various dispersants, hardening accelerators, limestone fine powder, fly ash, silica fine powder and the like can be blended in an appropriate amount as long as the effects of the present invention are not impaired. However, about reducing materials, such as coke powder, you may mix | blend about 20 mass% separately according to the use purpose separately.

  Now, when manufacturing the said non-baking agglomerated mineral based on the method of this invention, first, in addition to sintered powder, to the mixed raw material which consists of the said raw material for shaping | molding containing fine powder iron oxide, etc., any one or more of the said binders After adding other components as necessary, water is added to these mixed raw materials and stirred (kneaded), and then molded (granulated) to a thickness of more than 5 mm with a molding machine. A body (granulated material) is obtained to obtain a non-fired agglomerated mineral. In this case, if necessary, the granulated product may be placed on a shade and cured.

  As a molding method, any of a compression granulation method using a briquette molding machine and a rolling granulation method using a disk pelletizer or a drum type granulator may be used. The briquette molding machine mechanically compresses the particle group, so the filling rate of the molded product increases, and the green strength (strength immediately after molding. On the other hand, the cold strength is the strength of the particles after the binder is solidified. However, the cold strength is largely dependent on the quality and quantity of the binder, and there is no significant difference between the rolling granulation method and the compression granulation method. In general, the compression granulation method has a feature that it is easy to produce a uniform particle size and property as compared with the rolling granulation method, but has a high equipment cost and repair cost.

  In the present invention, curing and drying may be performed. In particular, in the production of conventional non-fired agglomerated minerals, drying after curing is not particularly carried out, and the non-fired agglomerated minerals obtained after curing are directly charged into the blast furnace as blast furnace ore raw materials. On the other hand, in the present invention, if necessary, the unfired agglomerate is cured, and then dried at a temperature of about 80 to 150 ° C. with a drying apparatus or the like until the blast furnace is charged. While improving the impact strength of the ore, the content of free moisture in the unfired agglomerated ore may be reduced to 4 mass% or less, preferably 2 mass% or less to maintain air permeability in the blast furnace.

  That is, if such a drying process is performed, the free water | moisture content in this unbaking agglomerated mineral can be evaporated. As a result, when the unfired agglomerated ore is put into a blast furnace, it does not expand and explode due to its vapor pressure (internal pressure) to be pulverized, and the air permeability in the furnace is not deteriorated.

  By the way, the unfired agglomerated mineral produced through the above-described production process suitable for the present invention has a particularly high crushing strength at a high temperature. That is, the load softening test conducted by the inventors (after reduction at 550 ° C., 700 ° C. and 900 ° C., after cooling, the reduction rate was calculated from the weight change of individual particles (12 samples), and the crushing strength was determined by autograph. The results are shown in FIGS. 5 to 7 in comparison with the sintered ore, but both were higher than the target crushing strength and there was no difference from the sintered ore.

  The particle size of the unfired agglomerated mineral produced by the application of the method of the present invention (spherical equivalent particle size in a normal temperature atmosphere) is preferably more than 5 mm to less than 50 mm, preferably about 8 to 30 mm. If the particle size of the unfired agglomerated mineral is 5 mm or less, the air permeability of the raw material packed layer when charged in the blast furnace may be deteriorated, while if the particle size is 50 mm or more, the reducibility may be reduced. It becomes more prominent when the size is 8-30 mm.

  Moreover, the non-calcined agglomerated mineral produced by the method suitable for the method of the present invention has a reduced powdering characteristic (RDI) of less than 30% and a reducibility (RI) of higher than 65%. According to the experiments conducted by the inventors, as shown in FIG. 8, results of RDI of 20% or less and RI of 73% or more were obtained, and sintered ore, calcined pellets, lump ore measured under the same conditions. Compared to the above, it has been clearly shown that it exhibits excellent properties as a blast furnace ore raw material.

In the above experiment, a 500 g sample was used, and this was reduced at 900 ° C. for 3 hours in an atmosphere of (a) RI test: CO 30 vol%, N ₂ 30 vol%.
(B) RDI test: Reduced at 550 ° C. for 0.5 hours in an atmosphere of CO 30 vol% and N ₂ 30 vol%, and shows the result for the ratio of drum test → 2.8 mm.

At least one or more of Portland cement, ground granulated blast furnace slag, phenol resin, and alumina cement as a binder to the sintered powder for return ore and the pre-furnace sieve powder (shown in Tables 1 to 4) as raw materials for molding The mixed raw material to which Rusner iron oxide powder was added as fine iron oxide was molded according to the production flow as shown in FIG. 1 and subjected to a predetermined curing treatment to produce a non-fired agglomerated ore. Here, as the Rusner iron oxide powder, the steel material pickling line collection powder described in paragraph (0030) was used.
Table 5 shows the chemical composition of the molding raw materials and other blended raw materials used. The components of the sintered powder and the pre-furnace sieve powder are the same, but the sintered powder has a slightly fine particle size and an average particle size of 1.49 mm. On the other hand, the pre-furnace sieve powder has a slightly coarse particle size and a particle size of 2.52 mm. As the Rusner iron oxide powder, one having an extremely high iron oxide content (≧ 99.4 mass%) and fine particles (the ratio of the particle size of 10 μm or less is 90 mass% or more) was used.

The unfired agglomerated ore of each example was charged into the blast furnace together with the iron ore raw material, and the changes in the cold strength and blast furnace operating status of the unfired agglomerated ore were investigated. The results are shown in Table 6 together with the blending particle size distribution of the sintering raw material and the binder blending amount. The blending ratio of the raw materials charged into the blast furnace was set as follows: uncalcined agglomerated mineral: 12 mass%, sintered ore: 79 mass%, lump ore: 9 mass%.
About the cold intensity | strength of a non-baking agglomerated ore, the powder rate in a yard and the powder rate in a blast furnace top were measured, and the difference (powdering rate at the time of transport) evaluated. If the agglomerate has a particle size exceeding 5 mm, it can be used as a raw material for a blast furnace, so particles of −5 mm (= particle size of 5 mm or less) are defined as powder, and the mass ratio is set to a powder rate of −5 mm. .

  Also, the “blow-out phenomenon” of the number of blow-throughs shown in Table 6 means that the flow of reducing gas is stopped by increasing the pressure loss in the blast furnace, the pressure in the furnace rises, and reaches a certain pressure. When this happens, it means a phenomenon in which the rising of the reducing gas explosively resumes. In this case, since the charge in the furnace moves with the gas simultaneously with the resumption of the gas flow, the distribution of the charge deposited in layers is disturbed. If the distribution of the charge is disturbed, the air permeability is further deteriorated, and problems such as poor reduction of iron oxide are caused. There is also concern about thermal adverse effects on various facilities due to mechanical damage to the furnace body due to the rise and rapid hot gas ejection.

Invention Example 1 is an example containing finely divided iron oxide and an inorganic / organic binder.
Invention Example 2 is an example in which curing is performed.
Invention Example 3 is an example of curing and drying.
Invention Example 4 is an example in which the amount of finely divided iron oxide is suppressed to 3 mass%.
Invention Example 5 is an example in which the amount of finely divided iron oxide is suppressed to 5 mass%.
Invention Example 6 is an example in which the amount of finely divided iron oxide is suppressed to 5 mass%.
Comparative Example 1 is an example that does not contain finely divided iron oxide and an organic binder.
Comparative Example 2 is an example that does not contain finely divided iron oxide.
Comparative Example 3 is an example that does not contain finely divided iron oxide and an organic binder.
The comparative example 4 is an example which does not contain fine powder iron oxide and an organic binder.

  As can be seen from the operation results shown in Table 6, in the example in which the non-calcined agglomerate suitable for the example of the present invention was charged, the non-calcined agglomerated mineral in the comparative example is being transported to the blast furnace. It turns out that there is little powdering of. In addition, when looking at the operation of the blast furnace, the amount of dredging is large, the ratio of reducing material is low, and there is no blow-through phenomenon. From these results, it is understood that blast furnace operation can be remarkably improved when the unfired agglomerated mineral produced by the method of the present invention is used.

  Although this invention is description regarding the manufacturing method of the non-baking agglomerated mineral using the sintered powder for return ore as a blast furnace ore raw material, it is applicable also to iron-making raw material manufacturing techniques, such as a fired agglomerated mineral.

It is a diagram which shows the manufacture flow of the ore raw material for blast furnaces which consists of a non-baking agglomerated mineral. It is a figure explaining the basic formula of solid phase sintering. It is a graph which shows the hot strength (nitrogen atmosphere) of an agglomerate. It is a graph which shows the hot intensity | strength (reducing atmosphere) of an agglomerate. It is a graph which shows the relationship between the reduction rate in 550 degreeC, and crushing strength of the unbaking agglomerated mineral manufactured by applying this invention method. It is a graph which shows the relationship between the reduction rate in 700 degreeC and the crushing strength of the unbaking agglomerated mineral manufactured by applying this invention method. It is a graph which shows the relationship between the reduction rate in 900 degreeC, and crushing intensity | strength of the unbaking agglomerated mineral manufactured by applying this invention method. It is a graph which shows the relationship between the reducibility and the reduction | restoration powdering characteristic about the non-baking agglomerated mineral manufactured by applying this invention method.

Explanation of symbols

1-3 Mixing tank 4 Fixed amount cutting device 5 Conveyor 6 1st mixer 7 2nd mixer 8 Raw material tank 9 Mixer 10 Kneader 11 Molding machine 12 Shaking sieve

Claims (10)

Sintered powder of 5 mm or less generated during the production of sintered ore is shaped and agglomerated without forming sintered sinter, thereby forming a non-fired agglomerated ore, which is used as a blast furnace ore raw material. In the method
The forming raw material for obtaining the unfired agglomerated mineral is composed of the sintered powder and fine iron oxide, and the forming raw material is further kneaded with a binder, and then formed into an unfired ingot. A method for producing an ore raw material for a blast furnace, characterized in that it is formed into a mineral ore. The method for producing an ore raw material for a blast furnace according to claim 1, wherein the raw material for molding further includes pre-furnace presieving powder. The method for producing an ore raw material for a blast furnace according to claim 1 or 2, wherein the forming raw material further contains at least one of dust, sludge, and iron ore powder. The finely divided iron oxide is Rusner iron oxide powder having a maximum particle size of 10 μm or less and containing 90 mass% or more of iron oxide, mill scale generated in the steel manufacturing process, refining dust, and 3 to 6 mass% contained in the blended raw material The method for producing an ore raw material for a blast furnace according to claim 1, wherein: The method for producing an ore raw material for a blast furnace according to claim 1, wherein the binder is an inorganic binder and / or an organic binder. The method for producing an ore raw material for a blast furnace according to claim 5, wherein the inorganic binder is at least one selected from blast furnace granulated slag, bentonite and water glass. The method for producing an ore raw material for blast furnace according to claim 5, wherein the organic binder is molasses or a synthetic resin binder. The method for producing an ore raw material for a blast furnace according to claim 7, wherein the synthetic resin binder is a phenol resin binder. The method for producing an ore raw material for a blast furnace according to any one of claims 1 to 8, wherein the unfired agglomerated ore has an RI (reducibility) of 65% or more. The method for producing an ore raw material for a blast furnace according to any one of claims 1 to 9, wherein the non-fired agglomerated mineral has an RDI (reduction powdering characteristic) of 30% or less.

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