JP2005264310A - Method for producing sintered ore - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing a raw material for sintering by which, in a sintering process where ore fines are pelletized/sintered to undergo agglomeration, the raw material for sintering can be formed into high-strength pseudo-pellets, productivity and product yield at sintering can be improved and sintered ore with excellent quality can be manufactured. <P>SOLUTION: In the method for manufacturing the sintered ore, an iron-containing raw material composed mainly of iron ore, an auxiliary raw material and a carbonaceous material are mixed and the resultant mixture is pelletized with the addition of water and then the resultant pellets are charged into a sintering machine to undergo sintering. In the above method, sodium montmorillonite is mixed with the above iron-containing raw material of <1 mm particle size in such a way that the mass proportion of the montmorillonite to the iron-containing raw material ranges from 0.1 to <5 mass%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a blast furnace sintered ore in an iron making process, and in particular, granulates for pseudo particles using an iron-containing raw material containing a large amount of fine ore, thereby improving air permeability, productivity, and product yield. The present invention relates to a method for producing a sintered ore excellent in quality as a raw material ore for blast furnace by performing good sintering.

  In general, a sintered ore used as a blast furnace raw ore in an iron making process is manufactured as follows.

  FIG. 1 schematically shows an example of a sintering facility.

  Iron-containing raw materials such as iron ore, auxiliaries such as limestone, dolomite, silica, and serpentine, and carbon materials such as coke powder and anthracite (hereinafter, these may be referred to as sintering raw materials), respectively. A predetermined blending amount is cut out from the storage tank 1, supplied to the drum mixer 4 through the surge hopper 2, and after mixing by the rotation of the drum mixer 4 or simultaneously with the mixing, a suitable amount of water 3 is added and granulated. A pseudo particle is used.

  These pseudo particles have coarse particles such as iron ore having a particle diameter of 1 mm or more (this is called core particles) as a central core, and surrounding iron-containing raw materials such as fine ores having a particle diameter of less than 1 mm, auxiliary raw materials, charcoal It is a granulated product with a structure to which the material is adhered, and it requires a predetermined strength in order to produce a sintered ore with good air permeability during the sintering process of the raw material and excellent quality.

  The granulated raw material for sintering is charged by a charging hopper / drum feeder 5 into a pallet truck of a sintering machine such as a Dwytroid type sintering machine.

  Using the ignition furnace 6 arranged on the raw material charging side, the carbon material in the surface layer of the raw material packed bed was ignited, and air was arranged at the lower part of the sintering machine from the upper side to the lower side of the raw material packed layer. It is sucked by the main blower 12 through the air box 7, heated and fired and discharged as sintered ore 9 while moving the combustion point of the carbonaceous material from the upper layer to the lower layer of the raw material packed bed, and then crushed to be a raw material for blast furnace As a sintered ore having an appropriate predetermined particle size.

  Dust generated from the raw material for sintering due to the suction of air is collected by the main duct 10 and the dust collector 11 and charged into the sintering machine as a raw material for sintering (hereinafter sometimes referred to as return ore). Used.

  In the production of sintered ore, as well as improving productivity and product yield, as raw materials for blast furnace, predetermined quality such as cold strength (TI), reducibility (RI), reduction dust resistance (RDI), etc. Is required.

Firing (sintering) of the raw material for sintering is combustion heat generated when the carbonaceous material in the raw material packed bed is burned by the air flowing between the raw material particles in the sintering machine, and the temperature is raised to a maximum temperature of about 1300 ° C. Then, a melt is formed with iron oxide in the iron-containing raw material and mainly CaO in the auxiliary raw material, and then gangue components such as SiO ₂ and Al ₂ O ₃ are melted, and then coarse ore The molten part between the particles is cooled, solidified and sintered.

  The sintered ore has a structure in which an unmelted portion made of coarse ore or the like remains in the molten / solidified structure, and the structure and mineral characteristics of the sintering are affected by the sintering raw material, heating and cooling conditions, and the like.

  Especially in the sintering machine, the air permeability (easy air flow) in the sintering raw material packed bed is greatly affected by the sintering conditions such as heating / cooling rate, maximum temperature, and melt component composition during the sintering process. Affecting the quality, productivity and product yield of sinter.

  The air permeability in the sintering raw material packed bed in the sintering machine is affected by the granulation property when the sintering raw material is made into pseudo particles, the strength of the obtained pseudo particles, and the sintering conditions.

  In particular, the mineral composition and crystal structure of iron ore, which is the main part of the sintering raw material, and the type and content of the gangue component influence the granulation properties of the raw material and the strength of the pseudo-particles. It is said to have a great influence on sex.

  FIG. 2 schematically shows a cross-sectional state of the raw material packed layer in the sintering machine in the sintering process.

  After the carbonaceous material in the surface layer of the raw material packed layer is ignited, the combustion point moves from the upper layer to the lower layer of the raw material packed layer, and the calcination / combustion zone 17, the dry zone 16, the wet zone 15, and the wet raw material 14 are It is formed.

  The wet zone 15 is an area where air containing a large amount of moisture in the raw material as water vapor is cooled and condensed through the upper calcination / combustion zone 17 and the dry zone 16. Because of the excess, the pseudo particles collapse, and as the combustion point approaches, the fine powder part is dissociated by drying, leading to deterioration in the air permeability of the entire raw material packed bed and an increase in dust generation.

  Moreover, the deterioration of the air permeability deteriorates the heated and melted state of the raw material, and this deterioration causes the quality such as the strength of the sintered ore and the yield reduction.

  Therefore, the following basic characteristics are required for pseudo particles obtained by granulating a raw material for sintering.

  (1) Coarse ore with a particle size of 1 mm or more, which becomes a core particle during granulation, has high adhesion (granulating property) to fine particles (ores, auxiliary materials, carbonaceous materials) of 0.5 mm or less. .

  (2) It has a pseudo particle strength so as not to collapse in the raw material charging and sintering process, particularly in a wet zone.

  Conventionally, various methods have been proposed for increasing the granulation property and pseudo particle strength of the sintering raw material and improving the air permeability. For example, since the granulating property of the raw material for sintering differs depending on the brand name of the iron ore that is the main raw material, improvement is made by considering selection of the brand name of the iron ore to be blended and the blending ratio.

  However, high-grade iron ore with relatively high quality, excellent granulation properties, and small amount of fine powder has limited resources. Furthermore, recently, it has been desired to use a large amount of low-grade iron ore that is less granulated and has a finer amount of powder, such as dry iron ore, which is less expensive than these high-grade iron ores and can be supplied stably. ing.

  On the other hand, various additives have been proposed for use in granulation in order to improve the granulation properties of the raw material for sintering. Examples of such granulating additives include cement, starch, sugar, molasses, gelatin, water glass, tar, lignate, polyvinyl alcohol, and polyacrylamide. Among these, cement, quick lime, cement Clinker powder and the like are used industrially.

  For example, Non-Patent Document 1 discloses a method in which quick lime is used as an additive for granulation for forming pseudo particles in a sintered ore production process.

  According to this, by adding quick lime to the sintered raw material, first, when granulating with a mixer, it is possible to promote the formation of pseudo particles, and secondly, the sintered raw material that has been converted to pseudo particles is sintered. In the process of filling the binder, igniting the carbonaceous material in the surface of the packed bed, passing air in the packed bed thickness direction, and proceeding with the sintering by moving the combustion point, in the process of drying and heating the raw material pseudo particles It is said that the pseudo particles can be prevented from collapsing and a uniform air flow can be maintained in the sintered layer.

However, when a calcium-based granulating additive such as quick lime is used as the granulating additive, the amount of use is limited by the basicity (CaO / SiO ₂ ) regulation as a blast furnace sintered ore. Therefore, it has been difficult to obtain a sufficient granulation effect.

In addition, in the patent document 1, the present applicant uses kaolin (chemical formula: Al ₂ Si ₂ O ₅ (OH) ₄ ), which is a kind of clay mineral, to improve the granulation property of the sintering raw material, and iron ore. A method has been proposed in which the content of kaolin contained as a viscous mineral in a sintered raw material such as stone is adjusted by blending the raw material, or kaolin is added separately as an additive for granulation.

Since the granulation property of the sintering raw material can be improved by adjusting the amount of kaolin present in the raw material such as iron ore by mixing the raw material, the above method is more economical than the method using a granulating agent such as quick lime. It is an excellent method. However, after charging the raw materials, kaolin cannot suppress the collapse of the raw material pseudo particles due to the weak water retention capability in the sintering process, especially in the wet zone where the water is excessive, and the air permeability of the entire raw material packed bed It has been found that it cannot be improved sufficiently.
JP 2003-49227 A Steelmaking Research No. 288 (1976), p9

  In view of the actual state of the prior art described above, the present invention is a method for producing sintered ore for blast furnace, which is inexpensive and has a large amount of reserves, but is poor in granulation and has a large amount of fine iron ore as a raw material for sintering. Even in the case of blending in, it is possible to improve the granulation property and pseudo particle strength of the raw material for sintering, maintaining good air permeability, productivity and product yield during sintering, and for blast furnace The present invention provides a method for producing a sintered ore for producing a sintered ore excellent in quality as a raw material ore.

  As a result of intensive studies to solve the above problems, the present inventors have found that a mineral classified as a montmorillonite group (smectite) among clay minerals plays an important role in improving the granulation property of a raw material for sintering. This is applied as an additive for granulation of the raw material for sintering, and the optimum addition amount range for improving the granulation property is found. completed.

  The gist of the present invention is as follows.

  (1) A method for producing a sintered ore by mixing an iron-containing raw material mainly composed of iron ore, an auxiliary raw material, and a carbonaceous material, adding water, granulating the mixture, and then charging and sintering. In the above, the montmorillonite is blended and mixed with the iron-containing raw material so that the mass ratio of the sodium-type montmorillonite to the iron-containing raw material having a particle size of less than 1 mm is less than 0.1 to 5% by mass. A method for producing sintered ore.

  (2) The method for producing a sintered ore according to (1), wherein the montmorillonite is sodium bentonite mainly composed of sodium-type montmorillonite.

  (3) The method for producing a sintered ore according to (1) or (2), wherein the montmorillonite is calcium bentonite mainly composed of calcium-type montmorillonite.

  According to the present invention, in the method for producing a blast furnace sintered ore, although it is cheap and has a large reserve, it is a case where a large amount of iron ore with poor granulation and many fine powder parts is blended as a raw material for sintering. In addition, the granulation property of the raw material for sintering and the strength of the pseudo particles can be improved.

  This makes it possible to maintain good air permeability, productivity, and product yield during sintering, and to produce a sintered ore with excellent quality as a blast furnace raw material ore.

  Details of the present invention will be described below.

  The present applicant proposed “Patentability in the sintering process of a sintering raw material”, which is a technical problem of the granulating method of a sintering raw material proposed in Patent Document 1 using kaolin, which is a kind of clay mineral, as a granulating agent. We have intensively studied the method for improving "".

  As a result, it is the same in that it is kaolin and clay mineral, but as explained below, sodium-type montmorillonite having higher water retention than kaolin or bainite containing this is required in terms of the mineral structure. By using it as a granulating agent, it has been found that, in the sintering process of the sintering raw material, in particular, even in a wet zone where moisture is excessive, the pseudo particles do not collapse and can sufficiently improve the air permeability.

  First, the characteristics of the mineral structure of sodium-type montmorillonite used as a granulating agent in the present invention will be described.

  In general, clay minerals have a viscous property in the presence of water, and their structures are separated into crystalline and amorphous, and mostly consist of fine layered silicates of 2 μm or less.

The structure of clay minerals consists of a tetrahedral layer in which Si ⁴⁺ (some Al ³⁺ ) ions are tetracoordinated to oxide ions (O ²⁻ ), Al ³⁺ , Fe ²⁺ , An octahedron layer in which ions such as Fe ³⁺ and Mg ²⁺ are coordinated to O ²⁻ and hydroxide ions (OH ⁻ ) is bonded 1: 1 or 2: 1, and It is composed of a layered structure in which they are stacked.

  The kaolin family is known as the 1: 1 type lattice structure of the tetrahedral layer and the octahedral layer (see Patent Document 1), and the montmorillonite group and illite group of the present invention are used as the 2: 1 type lattice structure. Etc. are known to exist.

  Montmorillonite (also called montmorillonite) belongs to a group of minerals having a three-layer structure collectively referred to as a montmorillonite group and has a layered lattice that swells.

The general formula of the chemical composition is represented by R _0.33 Al ₄ (Si _7.33 Al _0.67 ) O ₂₀ (OH) ₄ .nH ₂ O. R represents Na ⁺ , K ⁺ , Mg ²⁺ , and Ca ²⁺ .

FIG. 3 schematically shows the stratigraphy of the crystal structure of sodium-type montmorillonite (when R in the chemical composition formula is Na ⁺ ).

Sodium-type montmorillonite is composed of a Si—O layer having a SiO ₄ tetrahedral structure coordinated with Si ⁴⁺ ions at the center and an Al—OH layer having an AlO ₆ octahedral structure coordinated with Al ³⁺ ions at the center. It has a three-layer structure in which an Al—OH layer exists between two Si—O layers.

In the crystal structure of montmorillonite such as sodium-type, a portion of the SiO ₄ 4 tetrahedra forming the SiO layer, substituted Si coordinate to the center Al (SiO layer in the drawing, reference) And easily converted into an AlO ₄ tetrahedron.

Furthermore, a part of Al coordinated at the center of the AlO ₆ octahedron forming the Al—OH layer may be substituted with Mg and converted into an MgO ₆ octahedron (not shown).

In these cases, a negative (−) charge is generated in the crystal lattice constituting the Si—O layer or the Al—OH layer, and Na ⁺ ions and Ca ²⁺ ions are interrupted in the gaps of the crystal lattice. Charge neutrality will be maintained, and water will be retained in this gap. Due to such a crystal structure, montmorillonite is considered to have high water retention.

  FIG. 4 schematically shows the stratigraphy in the crystal structure of kaolin.

On the other hand, the crystal structure of kaolin consists SiO layer and AlO of _six octahedral Al (OH) ₃ layers of SiO ₄ 4 tetrahedra share the three vertices of SiO ₄ 4 tetrahedra, two-dimensionally connected This is a two-layer structure. The upper end of each layer of kaolin having such a crystal structure is occupied only by O—H, and hydrogen bonds due to this O—H are strong, so kaolin has a weak force of retaining water between crystal lattices.

  The cause of the insufficient air permeability in the sintering process of the sintered raw material, which is a problem of the granulating method of the sintered raw material using kaolin as a granulating agent proposed by the present applicant in Patent Document 1, is excessive. This is probably because the pseudoparticles collapsed due to the poor water retention of kaolin in the wet zone in the moisture state.

  Based on the above knowledge, the present invention has led to the idea of using sodium-type montmorillonite, which is particularly excellent in water retention among clay minerals, as a granulating agent for a sintering raw material.

  Sodium-type montmorillonite absorbs water in the presence of water and swells, and has a characteristic of becoming a gel when containing a large amount of water. For this reason, even in the wet zone at the time of sintering of the sintering raw material granulated using sodium-type montmorillonite as a granulating agent, it is possible to retain excess water and prevent the pseudo particles from collapsing.

  Bentonite is known as a mineral containing a large amount of sodium-type montmorillonite. Bentonite is a white clay-like rock composed mainly of montmorillonite.

Bentonite is composed mainly of sodium-type montmorillonite (general chemical formula: R _0.33 Al ₄ (Si _7.33 Al _0.67 ) O ₂₀ (OH) ₄ .nH ₂ O)) in which R in the chemical formula is Na ^+. Mainly sodium-type bentonite.

However, when bentonite is buried in a shallow area near the topsoil, it is affected by rainwater for a long time, Na ⁺ flows out, Ca ²⁺ remains, and R in the chemical formula of montmorillonite is It becomes calcium-type bentonite whose main component is calcium-type montmorillonite, which is Ca ²⁺ .

As weathering further progresses, Ca ²⁺ also flows out, leaving hydrogen (H ⁺ ) as water molecules, resulting in acid clay. Usually, bentonite is used as a general term for these.

The present invention utilizes the high water retention characteristic of montmorillonite, suppresses the decay of pseudo particles during the sintering process, and improves air permeability. Among montmorillonite, in particular, the chemical formula Na-type montmorillonite with R of Na ⁺ is preferable because of its excellent water retention and swelling properties. For the same reason, sodium bentonite containing a large amount of Na-type montmorillonite is preferred.

  Bentonite mainly composed of montmorillonite is generally used for civil engineering and construction, or as a water-stopping agent for waste treatment plants, casting mold forming agents, liquid thickeners, medical and cosmetic granulation. It is used for pelleting of chemicals, dust and lightweight aggregates.

  Bentonite mainly composed of montmorillonite used industrially for these purposes can be used in the present invention.

  And this invention mixes the iron-containing raw material which consists mainly of iron ore, an auxiliary raw material, and a carbonaceous material, and after adding water and granulating, it inserts into a sintering machine, sinters and sinters a sintered ore. In the manufacturing method, the montmorillonite is blended and mixed with the iron-containing raw material so that the mass ratio of the montmorillonite to the iron-containing raw material having a particle diameter of less than 1 mm is less than 0.1 to 5% by mass. To do.

  The pseudo particles obtained by granulation of the sintered raw material are obtained by attaching fine ore having a particle size of less than 1 mm (average of about 0.2 mm), auxiliary materials, and carbon materials to core particles having a particle size of 1 mm or more. In order to suppress the collapse at the time of sintering, it is necessary to enhance the adhesion of the fine powder part adhering to the core particles of 1 mm or more and sufficiently improve the pseudo particle strength, so the fine powder part of less than 1 mm contains iron. It adds so that content of montmorillonite may be less than 0.1-5 mass% with the mass ratio with respect to a raw material.

  When the content of montmorillonite is less than 0.1% by mass with respect to the iron-containing raw material having a particle size of less than 1 mm, the effect of improving the granulation property and improving the pseudo particle strength, and especially the water content during sintering Since the effect of improving the air permeability cannot be sufficiently obtained by sufficiently suppressing the pseudo particle collapse in the wet body band in an excessive state, the lower limit of the content of montmorillonite is set to 0.1 mass.

  On the other hand, when the content of montmorillonite is 5% by mass or more with respect to the iron-containing raw material having a particle size of less than 1 mm, the melt produced by the sintering reaction due to the Al component contained in the montmorillonite Therefore, the upper limit of the content of montmorillonite is made less than 5% by mass.

  Conventionally, clay minerals in iron ore have been examined by X-ray diffraction, microstructure observation with an optical microscope, electron microscope observation, etc. Recently, infrared absorption spectrum, nuclear magnetic resonance spectrum, dehydration temperature during heating, etc. The amount of kaolin is also quantitatively evaluated from the amount of dehydration, and it has become clear that the iron ore is particularly rich in kaolin as a clay mineral.

  Table 1 shows component compositions of montmorillonite, sodium bentonite (Na-bentonite), and calcium bentonite (Ca-bentonite), and Table 2 shows component compositions of various raw material ores. Table 3 shows three blending patterns in which coarse ores (+1 mm) and fine ores (−1 mm) of various raw material ores shown in Table 2 are blended in combination.

In addition, component elements such as SiO ₂ and Al ₂ O ₃ in Table 1 are measured according to JISM8205 “Fluorescence X-ray analysis method of iron ore”, and the water of crystallization in the mineral (C.W.) is , Measured according to JISM8211 “Method for quantifying compound water in iron ore”.

In addition, T. Fe is in JISM8212 “Method for quantifying total iron in iron ore”, and component elements such as SiO ₂ and Al ₂ O ₃ are in JISM8205 “Method for fluorescent X-ray analysis of iron ore” in crystal water (C.I. W.) was measured according to JISM8211 “Method for quantifying compound water in iron ore”.

Next, the various granulating agents shown in Table 4 are added to the blending raw materials blended in the blending pattern shown in Table 3 in the addition amounts shown in the same table, granulated to obtain pseudo particles, and then a sintering pot test. A sintered ore was produced by In this test, the evaluation was divided into two parts: granulation and sintering of the raw material. The granulation property of the raw material was evaluated by the pseudo-granulation index (GI _0.25 , GI _0.5 ) and the air permeability (JPU) of the packed bed before ignition in the sintering pot test.

The pseudo-granulation index of raw materials: GI _0.25 and GI _0.5 (%) were obtained by the following formulas.
GI _0.25 = {(A−B) / A} × 100
A: Mixing ratio of true particles of 0.25 mm or less B: Mixing ratio of pseudo particles of 0.25 mm or less

In the case of GI _0.5 , A: the mixing ratio of true particles of 0.5 mm or less, and B: the mixing ratio of pseudo particles of 0.5 mm or less.

It means that the higher the pseudo-granulation index of GI _0.25 and GI _0.5, the higher the pseudo-particle strength of the raw material.

Moreover, the air permeability of the packed layer before ignition in the sintering pot test: JPU was obtained by the following equation.
JPU = (F / A) (h / s) ^0.6
F: Flow rate (Nm ³ / min)
A: Suction area (m ² )
h: Charging layer thickness (m)
s: Negative pressure (mH ₂ O)

  It means that the air permeability of a raw material filling layer is so favorable that the said JPU value is large.

  Moreover, in this example, in addition to the production rate, yield, and sintering time in the sintering pot test as the sinterability evaluation, the quality characteristics of the sintered ore include the reduction dust resistance (RDI), the reduction rate. (RI) and tumbler strength (TI) were evaluated.

The reduction dust resistance (RDI) is a basis for estimating the dustability in the reduction of the sintered ore in a relatively low temperature region in the blast furnace, and the sample is 30% CO, 70% N _2. After reducing at 550 ° C. for 30 minutes in a reducing atmosphere, the sample is loaded into a predetermined rotation tester, rotated at a specified rotational speed, sieved with a predetermined sieve, and evaluated by mass% for each section. . The following formula shows the calculation formula.

RDI (%) = (w ₃ / w ₂ ) × 100
w ₂ : Mass (g) of the sample charged in the rotation tester
w ₃ : sample mass of 3 mm or less after sieving (g)

The reduction rate (RI) was calculated according to the following formula based on JIS M8713.
RI (%) = [(m ₁ −m ₂ ) / {m ₀ (0.430 w ₂ −0.111 w ₁ )}] × 10 ⁴
m ₀ : Weighed sample mass (g)
m ₁ : sample mass immediately before the start of reduction (g)
m ₂ : Sample mass (g) 3 hours after the start of reduction
w ₁ :% by mass of iron (II) oxide in the sample before reduction, and oxide by mass% of iron (II)
Calculated by multiplying by a conversion factor of 1.286 w ₂ : Total iron mass% of the sample before reduction, measured by ISO 2597

Tumbler strength: TI is based on JISM8712, rotating a sample in a rotating drum, sieving with a 6.3 mm sieve, sample mass m ₀ (g) subjected to the test, and +6.3 mm sample mass after the test From m ₁ (g), it is obtained by the following equation.
TI = (m ₁ / m ₀ ) × 100
Tumbler strength: TI is a strength representing resistance to pulverization / collapse due to impact of iron ore (sintered ore), and a larger value means higher resistance to pulverization / collapse.

  The amount of dust generated was evaluated based on the amount of dust (a large amount) generated during the sintering pot test by adding and granulating kaolin as a granulating agent.

Table 4 and FIGS. 5 to 7 show the pseudo particle strength (GI _0.25 , GI _0.5 ), air permeability of the raw material packed bed (JPU), and Table 5 shows operability (production rate, product yield, sintering time), firing The evaluation results of the ore quality characteristics (RI, RDI, TI) and the amount of generated dust are shown.

Inventive Examples 1 to 15 are examples in which montmorillonite is added as a granulating agent specified in the present invention within the scope of the present invention. In each case, the pseudo-granulation index is 77 or more with a GI _0.25 value of GI. _{The 0.5} value was 56 or more, and the air permeability was 30 or more in JPU. In addition, the evaluation results of sintered ore quality characteristics (reduction rate: RI, reduction dust resistance: RDI, tumbler strength: TI) and dust generation amount were also good.

Among Invention Examples 1 to 15, when compared under the same conditions, especially when sodium-type montmorillonite is used, the pseudo-granulation index (GI _0.25 value, GI _0.5 value) and air permeability (JPU) are more As a result, the effect of calcium type bentonite was less than that of sodium type bentonite.

  This is because Na-Bentonite contains Na-Montmorillonite as the main component, and also contains quartz and cristobalite. Because it is. In addition, Ca-bentonite is mainly composed of Ca-montmorillonite, but since it also contains Na-montmorillonite, the effect is small, but the effect of granulation can be obtained by increasing the amount of addition.

  Further, as apparent from the operability (production rate, product yield, sintering time) and sintered ore quality characteristics (RI, RDI, TI) of Invention Examples 1 to 15, the granulation property and air permeability are clearly shown. Improvements have shortened the sintering time and improved quality properties such as product yield, RI and strength of the sinter. This is probably because the high temperature holding time was shortened and the secondary hematite in the sintered ore was reduced. Furthermore, in the generation of dust during sintering, the generation of dust was small due to the effect of suppressing the collapse of particles in the wet zone.

  On the other hand, Comparative Examples 1 to 6 show examples in which the granulating agent is not added, or the montmorillonite of the present invention and the addition amount thereof are out of the scope of the present invention.

Comparative Examples 1 to 3 are examples in which no granulating agent is added, and Comparative Example 4 is an example in which 0.05% of Na-bentonite is added as a granulating agent, but montmorillonite is not added or the content thereof is Since it was lower than the range of the present invention, the pseudo-granulation index was 76% or less at a GI _0.25 value and 58% or less at a GI _0.5 value, and air permeability: JPU was 27 or less.

Comparative Example 5 is an example in which Na-bentonite was granulated at an addition rate of 8% higher than the range of the present invention, and the pseudogranulation index (GI _0.25 value, GI _0.5 value) and air permeability were good. It was. However, due to an increase in the Al component contained in a large amount of montmorillonite, the properties of the melt produced during sintering deteriorated, and the tumbler strength (TI) and reduction dust resistance (RDI) of the sintered ore were greatly reduced.

Comparative Example 6 was an example in which kaolin was added as a granulating agent, and the pseudo-granulation index (GI _0.25 value, GI _0.5 value) was good. However, since kaolin does not have a sufficiently high water retention capacity, the strength of pseudo particles in the wet zone during sintering cannot be maintained, resulting in a decrease in air permeability due to powdering due to disintegration and a large amount of dust generated during sintering. It was a result.

  According to the present invention, as described above, it is possible to produce a sintered ore excellent in quality as a blast furnace raw material ore. Therefore, the present invention has high applicability in the steel industry.

It is a figure showing an example of sintering equipment roughly. It is a figure which shows typically the sintering cross-sectional condition of a pallet top charging raw material. It is a figure which shows typically the stratigraphy in the crystal structure of Na type montmorillonite. It is a figure which shows typically the stratigraphy in the crystal structure of a kaolin. It is a figure which shows _GI0.25 of an Example and a comparative example. It is a figure which shows GI _0.5 of an Example and a comparative example. It is a figure which shows JPU of an Example and a comparative example. It is a figure which shows the production rate, product yield, and sintering time of an Example and a comparative example. It is a figure which shows RI, RDI, and TI of an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Storage tank 2 ... Surge hopper 3 ... Water 4 ... Drum mixer 5 ... Charging hopper / drum feeder 6 ... Ignition furnace 7 ... Wind box 8 ... Sinter zone 9 ... Sinter ore 10 ... Main duct 11 ... Dust collector 12 ... main blower 13 ... chimney 14 ... wet raw material 15 ... wet zone 16 ... dry zone 17 ... calcination and combustion zone

Claims (3)

  In a method in which iron-containing raw materials mainly composed of iron ore, auxiliary materials and carbonaceous materials are mixed, water is added and granulated, then charged into a sintering machine and sintered to produce sintered ore. Sintering characterized by blending and mixing montmorillonite in the iron-containing raw material so that the mass ratio of sodium-type montmorillonite to the iron-containing raw material having a diameter of less than 1 mm is less than 0.1 to 5% by mass. Manufacturing method of ore.   The method for producing a sintered ore according to claim 1, wherein the montmorillonite is sodium bentonite whose main component is sodium montmorillonite.   The method for producing a sintered ore according to claim 1 or 2, wherein the montmorillonite is calcium bentonite mainly composed of calcium-type montmorillonite.

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