JP4220908B2 - Method for producing unfired agglomerated mineral - Google Patents

Description

  The present invention relates to a method for producing a non-fired agglomerated mineral, and particularly to a method capable of efficiently producing a high-strength non-fired agglomerated mineral according to the operating state.

  In the blast furnace for iron making, from the viewpoints of handleability, operability, etc., the powdered iron making raw material is granulated in advance and then sintered into a granular sinter or pelletized. It has been. For example, the sintered ore is generally obtained by using an iron oxide raw material such as iron ore as a main raw material, and adding powdered limestone or silica as an auxiliary raw material, followed by sintering.

However, these sintered ores and pellets have problems such as requiring a large amount of energy for production and a large amount of CO ₂ emission. Also, in recent years, as the production of high-quality ores has decreased, various types of ores with different qualities may be used as raw materials for ironmaking. However, there are problems such as difficulty in molding and difficulty in obtaining the intended strength level.

  As a raw material for iron making other than the above-mentioned sintered ore and pellets, a non-fired agglomerated mineral in which an oxide raw material and a secondary raw material are combined using cement or the like as a binder has been proposed (for example, Patent Document 1). Further, from the viewpoint of cost reduction and effective utilization of valuable waste materials, a method of producing agglomerated ore by extrusion molding using blast furnace dust as a binder has been proposed (for example, Patent Document 2). However, since these methods require a long time for curing, it is necessary to secure a wide curing yard. In addition, it takes time to manufacture, and it is difficult to prepare the raw materials for iron making according to the situation of the ironmaking operation.

In order to solve such problems, a method for producing agglomerated minerals has been proposed in which curing temperature is increased and curing is performed in a short time (for example, Patent Document 3). However, in this method, equipment for heating is necessary, and raw agglomerates are likely to stick together at the time of heating, and it is difficult to efficiently produce agglomerated minerals having a uniform shape.
JP 2003-342646 A JP 2002-235122 A JP-A-12-119760

  This invention is made | formed in view of the said situation, Comprising: The objective is to provide the method which can manufacture a high intensity | strength agglomerated mineral efficiently according to an operating state, without baking. is there.

  The method for producing an unfired agglomerated mineral according to the present invention is a method for producing an unfired agglomerated ore for blast furnace charging, in which water is added to an agglomerated mineral composition containing an iron oxide raw material, clay and a hydraulic binder. After being kneaded and then kneaded, extrusion molding is performed while vacuum degassing, and the resulting molded product is cured.

  The above “agglomerated ore composition” refers to “a state in which an agglomerated mineral raw material containing iron oxide raw material, clay and hydraulic binder is blended” before adding water, and is shown below. "Mass%" shall mean the mass ratio with respect to this whole agglomerated mineral composition.

  Cement and / or blast furnace slag can be used as the hydraulic binder. Further, the blending amount of the iron oxide raw material is preferably 60% by mass or more of the entire agglomerated composition, and the blending amount of the clay is 5 to 30% by mass of the entire agglomerated composition. Is good.

  According to the present invention, a necessary amount of agglomerate can be produced at any time according to the operation situation without securing a wide curing yard. In addition, a high-strength agglomerated ore can be efficiently produced without considering the quality of the ore.

  As described above, the present inventors have conducted intensive studies with the aim of establishing a method that can efficiently produce a necessary amount of high-strength agglomerated minerals according to the operation status. As a result, the inventors have found that a high-strength agglomerated mineral can be produced in a short period of time when the extrusion molding is performed while degassing by vacuum suction, and the present invention has been conceived.

  By extruding while vacuum degassing in this way, even when using ore with poor sinterability and formability, it can be molded well, and the obtained agglomerated ore is only cured for a short time Thus, a high-strength non-fired agglomerated mineral can be obtained.

  In the vacuum deaeration, the pressure in the extrusion molding apparatus into which the raw material is charged is preferably reduced to 0.016 MPa or less on an absolute basis, and more preferably 0.005 MPa or less. In addition to the screw-type twin-screw extruder used in the examples described later, a screw-type single-screw extruder or a roller-type extruder can be used for the extrusion.

  As a forming method, in the following example, the extruded continuous molded product is cut to obtain a cylindrical agglomerate, but the shape of the agglomerated mineral is not limited to this, and after the continuous molded product is cut Further, it can be formed into various shapes such as a spherical shape and a gravel shape by further press molding.

  In the present invention, curing may be performed as described below after the above molding, and granulation is not necessary unlike the conventional pellet manufacturing method. Moreover, since the hydraulic binder which hardens | cures at room temperature by adding water is used, it is not necessary to bake.

  In the present invention, an agglomerated mineral composition containing an iron oxide raw material, clay and a hydraulic binder is used as a raw material for producing the agglomerated mineral.

As the iron oxide raw material, blast furnace dust, converter dust, mill scale and the like containing iron oxide as a main component can be used in addition to iron ore generally used as a raw material for iron making. Various types of iron ores can be used. For example, hematite (hematite: Fe ₂ O ₃ ), magnetite (magnetite: Fe ₃ O ₄ ), goethite (Fe ₂ O ₃ .H ₂ O), etc. Dolomite ore may be used as a limonite-based ore containing a large amount of Mg or a MgO-containing substance. Also, maramamba ore with low sinterability can be used.

  The blending amount of the iron oxide raw material is preferably 60% by mass or more in terms of the proportion of the entire agglomerated mineral composition. This is because the agglomerated mineral with a high compounding amount of the iron oxide raw material and a high iron content can efficiently produce a large amount of metallic iron in the ironmaking, and more preferably 70 mass% or more of the total compounding raw material. Is good. In addition, the upper limit of the compounding amount of the iron oxide raw material may be determined in consideration of the compounding amount of clay to be compounded for improving moldability and the hydraulic binder to be compounded for improving strength.

  The size (particle size) of the iron oxide raw material to be used is not particularly limited, but should be determined in consideration of the following tendency.

  That is, as will become apparent in the examples described later, as the particle size of the iron oxide raw material (ore) increases, the strength of the iron oxide raw material (ore) is reflected in the strength of the agglomerated mineral. It seems easy to achieve high strength. However, on the other hand, the fluidity is deteriorated, so-called plasticity is lowered and it becomes difficult to mold, and as a result, the amount of iron oxide raw material (ore) is forced to be reduced, or the binder or the like is required.

  On the other hand, a relatively strong agglomerate can also be obtained by using a fine iron oxide raw material. In this case, even if the blending amount of clay or hydraulic binder is somewhat reduced, good molding is achieved. Can be secured. However, a pretreatment process such as pulverization for miniaturization is required.

  Therefore, it is necessary to determine the optimum size (particle size) of the iron oxide raw material to be used in consideration of the intended strength level, iron content (T.Fe) in the agglomerate and formability. Considering availability and blast furnace operability, it is desirable to use those having an average particle size of about 5 mm or less. However, in some cases, the combined use of coarse grains and fine grains seems to be effective.

  In the present invention, clay is essential as one of the raw material components. It is because the plasticity at the time of shaping | molding can be ensured by mix | blending clay, and it can shape | mold favorably. The clay in the present invention is a highly plastic soil material mainly composed of a fine hydrous aluminum silicate material, and mainly contains kaolin, halloyite, diaspore, quartz, sericite, phyllite, etc. Although it says a thing, about the kind of concrete clay, it is not specifically limited, The quarrying waste soil, the waste soil for ceramics, etc. can be used.

  The blending amount of the clay is preferably in the range of 5 to 30% by mass in the ratio of the entire agglomerated mineral composition. As will be described later, the proper blending amount of clay depends on the amount and size of the iron oxide raw material to be used, but if it is too small, the kneaded product becomes insufficiently plastic and cannot be molded well. It is good to mix | blend so that it may become 5 mass% or more. More preferably, it is 10 mass% or more. On the other hand, if the amount of clay is too large, the iron content in the agglomerate will be reduced, leading to a decrease in the productivity of the blast furnace. It is preferable to set it as 30 mass% or less of the whole mineral composition. More preferably, it is 25 mass% or less.

  Moreover, in this invention, the hydraulic binder which hardens | cures age by adding water is used. By mixing and curing the hydraulic binder, a high-strength agglomerate can be obtained without firing. As the hydraulic binder, for example, cement, bentonite, blast furnace slag, or the like can be used.

  As cement, ordinary so-called Portland cement commercially available, early strong Portland cement, super early strong Portland cement, moderately hot Portland cement, blast furnace cement containing blast furnace slag, silica cement containing silica in Portland cement, Fly ash cement containing fly ash, alumina cement mixed with alumina, or the like can be used.

As another example of the hydraulic binder, blast furnace slag and converter slag containing SiO, CaO, and Al ₂ O ₃ as main components can be used.

  Furthermore, bentonite (made of ore such as volcanic ash deposited on the sea floor when the volcano erupted is altered, and has extremely high water absorption performance, and has the property of expanding into a paste when absorbed. ) May be used as a hydraulic binder, and sodium-based or calcium-based ones can be used without any particular limitation on the brand.

  These hydraulic binders are mainly used alone, but two or more kinds can be used in combination if necessary.

  In addition, what is necessary is just to determine suitably the compounding quantity of the said hydraulic binder, considering the intensity | strength, moldability, curing time, etc. which are calculated | required by an agglomerate, but in that case, the iron content (T in an agglomerate) .Fe), the amount of ore and the amount of clay from the viewpoint of extrudability are also considered.

  In the following examples, an agglomerated composition composed of ore (oxide raw material), clay and cement (hydraulic binder) is used as the raw material of the agglomerated mineral. In addition to these oxide raw materials, clay and hydraulic binder, which are the main composition, additives may be included, for example, a curing agent mainly composed of inorganic metal elements may be included for adjusting the curing time. .

  In the present invention, water is added to the agglomerated mineral composition containing the iron oxide raw material, clay and hydraulic binder and kneaded. The water added at this time has a moisture content of 14% by mass ± 5% by mass. It is better to adjust as follows.

  The above kneading may be performed by a generally used method, and a mixer, a kneader, a biaxial or single screw kneader can be used. The kneaded product thus obtained is subjected to the above-described extrusion molding.

  Then, the molded product (green agglomerate) obtained by extrusion molding may be cured in a curing yard (preferably an indoor curing yard). Curing may be performed in a state where the molded products (green agglomerated minerals) are arranged and arranged, or may be performed in a somewhat messy state from the viewpoint of productivity.

  The term “curing” as used in the present invention refers to curing the green agglomerate by leaving it in the air (in the air).

  According to the method of the present invention, the molded products do not stick to each other immediately after extrusion molding or during curing, and it is not necessary to provide a sufficient interval between the molded products. Even if the molded products are stacked and cured as described above, the handling workability after curing is extremely good.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

  As schematically shown in FIG. 1, iron ore 1 (sintered ore; under sinter of product sintered ore), cement 2 (ordinary Portland cement) and clay 3 (quarry waste) as raw materials for iron oxide The agglomerated mineral composition comprising soil) was conveyed to the kneader 5 by the conveyor 4, and kneaded while adjusting the water content to about 14% by mass by adding water 6 with the kneader 5. Then, the kneaded product is charged into a vacuum extrusion molding machine 7 and extruded while being vacuum degassed (0.016 MPa in terms of MPa absolute), and the continuous molded product 8 obtained is cut with a cutter 9 to obtain a diameter: A cylindrical shaped product (raw agglomerated mineral) 10 having a height of about 50 mm and a height of about 100 mm was obtained.

  And the said agglomerated ore 10 was moved to the indoor curing yard 11, and it aged at room temperature for 24 hours, 168 hours, 192 hours, or 672 hours, and obtained the agglomerated mineral. The compressive strength of the agglomerated ore thus obtained was measured using a commercially available compressive strength tester shown below. These results are also shown in Table 1.

<Compressive strength tester>
Manufacturer name: Mori Testing Machine Co., Ltd. Format: Amsler type Applicable standards: JIS B 7721

Hereinafter, the results of Table 1 will be considered. First, as a preliminary test, in order to confirm whether extrusion molding can be performed satisfactorily, No. 1 shown in Table 1 is used. Agglomerate was produced using 1 raw material. As a result, no. In No. 1, a sufficiently high strength exceeding 20 N / mm ² was obtained by curing for one day, and it was confirmed that agglomerated ore that could be used as a raw material for iron making was obtained by curing for one day. No. It was also found that the strength of the agglomerate can be further increased by further increasing the curing time (1 week or 1 month).

  Next, a case where the iron content (T.Fe) content in the agglomerated ore as a raw material for iron making was increased was examined. That is, no. An experiment was conducted in which the amount of clay and cement in the composition No. 1 was reduced and the amount of ore was increased to produce agglomerates. The result was No. Shown in 2 and 3.

  This No. 2 and no. From the results of No. 3, the ore having a particle size of about 5 mm or less was used, and the blending amount of clay and / or cement was No. It has been found that when it is decreased from 1, the moldability becomes insufficient.

  Therefore, an ore with a fine particle size (particle size of about 0.25 mm or less) is used, and the mixing amount of clay and cement is the above-mentioned No. 1. 2 and no. Agglomerate was produced in the same manner as in No. 3. The result was No. 4 and no. As shown in FIG. This No. 4 and no. From the result of 5, it can be seen that if an ore with a fine particle size is used, it can be sufficiently molded even if the mixing amount of clay and / or cement is reduced.

  The strength of the agglomerated ore is no. 4 and no. When using an ore with a larger particle size than No. 5 (No. 1), it can be achieved in a shorter period (one day). For Nos. 4 and 5, the curing time was 168 hours (7 days). It can be seen that agglomerates with a strength higher than 1 are obtained. No. For 4 and 5, even if the curing time is further extended (672 hours), the strength does not increase dramatically, and it seems that the purpose can be sufficiently achieved by curing for 7 days.

  No. 6 and no. 7 is an intermediate size between a relatively large size ore (particle size upper limit: 5 mm, used in Nos. 1 to 3) and a fine size ore (particle size upper limit: 0.25 mm, used in Nos. 4 and 5). Is the result of investigating the influence of the ore particle size on the relationship between the curing time and strength and on the formability. No. 6 is an ore with an upper limit of particle size: 0.5 mm. 7 is an experimental example using an ore having a particle size upper limit of 1.0 mm.

  These No. 6 and no. Although the data of 7 was not fully elucidated, no. 6 and no. If 7 is compared, it seems that the one using a larger size ore can obtain a higher strength in the same curing time. However, no. 2 or No. As shown in FIG. 3, it seems that if the ore size is larger, the moldability may be deteriorated.

  No. 6 and no. From the comparison of No. 7, no. No. 7 has a higher strength agglomerate. 6, 7 and No. 4 is compared with the above No. 4 in the same curing time by using a very fine ore as an ore. It seems that the same strength as 7 or higher is obtained.

  A graph summarizing these experimental results is shown in FIG. From FIG. 2, it can be considered as follows.

Strength at which the compact into pellets in the usual way, but is generally 15~18N / mm ² approximately, according to the method of the present invention, the mass Naruko about 20N / mm ^2, No. No. 1 ore-sized material can be obtained in about one day. If a raw material of composition 4 ore size is used, it can be obtained by curing for about 100 hours (about 4 days or more). No. No. 1 agglomerated ore of about 30 N / mm ² can be obtained in about 50 hours (about 2 days or more). It can be seen that if a raw material of composition 4 ore size is used, the same level can be obtained by curing for about 7 days.

It is process drawing which showed the embodiment of this invention schematically. It is the graph which showed the relationship between the curing time of each sample, and the compression density of a product (agglomerated ore).

Explanation of symbols

1 Iron oxide raw material (Ore)
2 Cement 3 Clay 4 Conveyor 5 Kneading machine 6 Water 7 Vacuum extrusion molding machine 8 Continuous molded product 9 Cutter 10 Molded product (green ingot ore)
11 Curing Yard

Claims (4)

  In a method for producing an unfired agglomerate for blast furnace charging, water is added to an agglomerated mineral composition containing an iron oxide raw material, clay and a hydraulic binder, and then kneaded, followed by extrusion molding while vacuum degassing. A method for producing a non-fired agglomerated ore characterized by curing the molded product.   The method for producing a non-fired agglomerated mineral according to claim 1, wherein cement and / or blast furnace slag are used as the hydraulic binder.   The manufacturing method of the non-baking agglomerated minerals of Claim 1 or 2 whose compounding quantity of the said iron oxide raw material is 60 mass% or more of the whole agglomerated mineral composition.   The method for producing an unfired agglomerated mineral according to any one of claims 1 to 3, wherein the blending amount of the clay is 5 to 30% by mass of the entire agglomerated mineral composition.

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