JP2003027148A - Method for manufacturing sintered ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing sintered ore by which the productivity and product yield of the sintered ore can be improved in the case where iron ore containing hydrous iron oxides is used as a raw material for sintering and also the quality of the sintered ore, such as cold strength and reduction degradation characteristic, can be improved. SOLUTION: The iron ore containing the hydrous iron oxides is previously roasted in a roasting furnace to undergo removal of bound water in the hydrous iron oxides and then mixed with the other raw materials for sintering. The resultant mixture is pelletized and charged into a sintering machine to undergo sintering. In this method for sintering the sintered ore, heating temperature at the above roasting is set at a value not lower than the dissociation temperature of the bound water in the hydrous iron oxides and lower than the dissociation temperature of structure water in clay minerals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered ore using an iron ore containing iron oxide hydroxide as an iron ore mixed in a sintering raw material, and more particularly, to a method for producing iron ore containing iron oxide hydroxide. The present invention relates to a method for producing a sinter having high quality such as reduction pulverization resistance by improving productivity and product yield during sintering when using iron ore.

[0002]

2. Description of the Related Art Sintered ore used as a main raw material in the blast furnace iron making method is used as an iron-containing raw material such as crushed iron ore powder, limestone,
Dolomite, silica stone, serpentine, and other auxiliary materials, and coke powder, anthracite, and other carbonaceous materials are mixed, and an appropriate amount of water is added to these sintering materials to mix and granulate, and then Dwightroid-type sintering. Machine or traveling great type firing machine, ignite the carbonaceous material in the surface layer of the raw material-filled bed, and suck air downward to move the burning point of the carbonaceous material from above to below. Is mass-produced by heating and baking.

In the production of sinter, the productivity of sinter and the product yield are improved, as well as cold strength, reducibility,
Although certain qualities such as resistance to reduction pulverization as raw materials for blast furnaces are required, these depend on the mineral composition and crystal structure of iron ore, which is the main raw material of the sintering raw material.

Generally, iron ores are roughly classified into magnetite, hematite, and limonite when classified by mineral composition. Magnetite
It is mainly composed of magnetite (Fe ₃ O ₄ ), has a high-density crystal grain structure, is hard to be reduced in the sintering process, and remains almost as it is. Hematite is hematite (α-Fe
₂ O ₃ ) as a main component and has a crystal grain structure having a density intermediate between those of magnetite and limonite, and is reduced to Fe ₃ O ₄ in the sintering process, or calcium ferrite (CaO・ Fe ₂ O ₃ )

Further, limonite (Fe)₂O₃・
nH₂O) is Goethite (Fe)₂O₃・ H₂O
Or α-FeO (OH)) as the main component and low density
It has a fine grain structure and nH during the sintering process.₂O (bound water)
Decomposes and evaporates, α-Fe₂O ₃Through Fe₃O_FourIs reduced to
It

Limonite (Fe ₂ O ₃ .nH ₂ O) is
Recent studies in naturally occurring form, goethite _{(goethite) (Fe 2 O 3 · H} 2 O or α-FeO (OH)),
Hematite (Fe ₂ O ₃ · H ₂ O or γ-FeO (O
H)) and hydrohematite (Fe ₂ O ₃ .1 / 2H ₂ O) and the like.

Further, in iron ores, in addition to the above-mentioned main iron oxides or iron hydroxides, quartz (SiO ₂ ) as gangue,
Alumina (Al ₂ O ₃ ), Kaolin (Basic chemical formula: Al ₂
Si ₂ O ₅ (OH) ₄ ), montmorillonite, etc. are contained, and the kind and content of gangue, together with the mineral composition and crystal structure of iron ore, are the raw materials for producing sinter. It has a great effect on granulation, air permeability during sintering and sinterability, and affects the quality of sinter such as cold strength and resistance to reduction pulverization.

From the above, in the usual production of sintered ore, by adjusting the mixing ratio of various brands of iron ore, which is the main raw material of the sintering raw material, the predetermined production conditions of the sintered ore can be obtained. And quality control is done.

As the world's iron ore resources, high-quality hematite, which has been frequently used up to now, is in the direction of depletion, and it is predicted that its main mine will be exhausted in recent years as it is. On the other hand, as compared with high-quality hematite and magnetite, the deposit of limonite deposit is enormous, and the mining cost is relatively low and the supply is stable, so if a large amount of limonite can be used as a sintering raw material. It has great significance in terms of economic effects such as cost reduction and effective use of iron ore resources.

However, limonite (Fe ₂ O ₃ .nH ₂
O) easily produces calcium ferrite (CaO.Fe ₂ O ₃ ) that contributes to the cold strength of the sinter by the assimilation reaction, but in the heating process before the assimilation reaction occurs, the bound water (nH ₂ O) decomposes and evaporates to generate cracks in the ore, and the subsequent assimilation reaction causes the resulting melt to enter the cracks and rapidly promote the assimilation reaction. The structure becomes a fragile structure in which large pores remain, and the sinter tends to become fragile.

Furthermore, when a large amount of gangue such as SiO ₂ and Al ₂ O ₃ is contained in limonite, the assimilation structure is a connective structure of glassy silicate and granular hematite particles, which are more brittle than calcium ferrite. And the sinter becomes more brittle.

When the limonite is sintered, extra heat energy is used in order to decompose and evaporate the bound water (nH ₂ O) contained in the limonite in the heating process. Coke powder required to maintain a predetermined temperature (maximum heating temperature: 1300 ° C.) during sintering, as compared with the case of sintering hematite or magnetite containing less nH ₂ O),
As the amount of carbonaceous materials such as anthracite increases, the increase in the amount of carbonaceous materials increases the local area where the calorific value is excessive in the sintering filling bed, resulting in the expansion of the red tropical zone, and
As a result, the air permeability is lowered, and the productivity of the sinter and the product yield are lowered.

From the above, when a large amount of limonite is used as a sintering raw material, the productivity or product yield of the sinter decreases, and the quality of the sinter such as cold strength and resistance to reduction pulverization deteriorates. However, there was no choice but to limit the amount of use.

As a method for improving the production and quality problems when a large amount of such limonite is used as a sintering raw material, there is a conventional method, for example, JP-A-52-56.
As disclosed in Japanese Unexamined Patent Application Publication No. 002, Japanese Patent Application Laid-Open No. Hei 5-339653, Japanese Unexamined Patent Application Publication No. 3-10027, etc., before limonite is charged into a sintering machine, it is heated by a roasting machine or the like. Reduce the content of bound water in limonite,
Decomposition and evaporation of bound water in the process of sintering in a calcination machine, and the resulting deterioration of sinter quality such as sinter productivity, product yield, cold strength and resistance to reduction pulverization. A method of suppressing is disclosed.

[0015]

However, according to the conventional methods disclosed in Japanese Patent Laid-Open Nos. 52-56002, 5-339653, and 3-1-10027, a limonite roasting machine or the like is used. The heating temperature during the heat treatment is set to a high temperature of 500 ° C. or higher, and the effect of efficiently reducing the content of bound water in limonite can be sufficiently obtained. There was a problem in that the granulation property when the powder was mixed with other sintering raw materials and water for granulation was deteriorated as compared with limonite before roasting.

[0016] In view of the problems of the prior art, the present invention, after roasting iron ore containing hydrous iron oxide such as limonite in advance with a roasting machine, produces a sintered ore with a sintering machine. In the method, by optimizing the roasting conditions for reducing the content of bound water in iron oxide without reducing the granulation properties of the iron ore after roasting, limonite is used as a sintering raw material. Provided is a method for producing a sintered ore, which can improve the productivity and product yield of the sintered ore when used in a large amount and can improve the quality of the sintered ore such as resistance to reduction pulverization.

[0017]

Means for Solving the Problems As a result of intensive investigations by the present inventors, the cause of the decrease in the granulating property of limonite after roasting is
It was found that clay minerals contained in limonite, especially kaolin, were altered by dehydration at high temperatures, and it was determined by optimal setting of temperature conditions for roasting iron ores containing hydrous iron oxide such as limonite. , We have found a method that can reduce the water of crystallization in hydrous iron oxide without deteriorating kaolin in iron ore.

The present invention was made based on this finding, and the gist of the invention is as follows. (1) Iron ore containing hydrous iron oxide is roasted in a roasting furnace in advance to remove bound water in hydrous iron oxide, and then mixed and granulated with other sintering raw materials, and then used in a sintering machine. In the method for producing a sinter that is charged and sintered, the heating temperature during roasting is set to a temperature range that is equal to or higher than the dissociation temperature of bound water in hydrous iron oxide and is lower than the dissociation temperature of structural water in clay minerals. A method for producing a sinter, comprising: (2) The dissociation temperature of the bound water in the hydrous iron oxide and the dissociation temperature of the structural water in the clay mineral are the heating temperature during roasting,
It is determined based on the relationship between the absorption intensity due to the bound water in the hydrous iron oxide and the absorption intensity due to the structural water in the clay mineral in the infrared absorption spectrum after roasting at the heating temperature. The method for producing a sinter according to (1) above. (3) The absorption intensity resulting from the bound water in the iron oxide hydroxide is 3600 to 2800 (1 / c in the infrared absorption spectrum).
m) is measured in the wave number range, and the absorption intensity due to structural water in the clay mineral is 3800 to
The method for producing a sinter according to (2) above, which is measured in a wave number range of 3600 (1 / cm). (4) The sintering according to any one of (1) to (3) above, wherein the amount of water in the iron ore containing hydrous iron oxide is reduced to 2.0% by mass or less by the roasting. Method of producing ore. (5) A part of the waste heat of the cooler of the sintering machine is used as a heat source during the roasting, (1) to
The method for producing a sintered ore according to any one of (4). (6) The method for producing a sinter according to any of (1) to (5) above, wherein the clay mineral is kaolin.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below.

The present inventors have paid attention to the behavior of clay minerals in iron ore when roasting iron ore containing hydrous iron oxide such as limonite by a roasting machine, and under various temperature conditions, iron ore After roasting, the relationship between structural water in clay minerals and bound water in hydrous iron oxide was investigated by experiments.

Generally, kaolin and monmo are contained in iron ore.
Lilonite, illite, vermiculite, chlorite, etc.
Contains clay minerals of
(Al ₂Si₂O_Five(OH)_Four) Content is high. these
Clay minerals become viscous when mixed with water, so
It was thought to play an important role in granulation.

Further, iron-containing hydroxides present in iron ores such as limonite (Fe ₂ O ₃ .nH ₂ O) have been recently researched, and most of them are impure goethite (goethite) in a naturally occurring form. ) (Fe ₂ O ₃ · H ₂ O or α-FeO (O
H)), hematite (Fe ₂ O ₃ .H ₂ O or γ-FeO
(OH)) has been confirmed.

As a method for grasping the behavior of dehydration of structural water in clay minerals and bound water in hydrous iron oxide in iron ore upon heating, an infrared absorption spectrum method, X
Examples include a method by line diffraction, a method by thermal analysis, a method by which water content generated when a sample is heated is measured, and a method by nuclear magnetic resonance method.

Among these methods, the method by thermal analysis and the method for measuring the water content generated at the time of heating the sample are as follows. This is a method of measuring the amount of generation and the like, and it takes a long time for the measurement. The method based on the nuclear magnetic resonance method is not suitable for iron ore in which a magnetic substance coexists, because the measurement is performed in a high magnetic field. The X-ray diffraction method is an analysis based on the crystal structure, but it has a drawback that sensitivity cannot be obtained if the crystallinity is poor.

On the other hand, the method using infrared absorption spectrum is as follows:
Infrared spectrophotometer by mixing sample with potassium bromide and molding
Is a simple and accurate method, so goethite
(Α-FeO (OH)), hematite (γ-FeO (O)
H)) and kaolin (Al ₂Si₂O_Five(OH)_Four)
It is ideal for understanding the dehydration status of.

In FIG. 2, goethite (α-FeO (OH)) and scheelite (γ-F), which are the main hydrous iron oxides in limonite, are shown.
eO (OH)) and kaolin (Al ₂ Si ₂ O ₅ (OH) ₄ ) which is a clay mineral in limonite in air at 50-60
Thermogravimetric change when heated to 0 ° C at 10 ° C / min (T
G) is shown. In addition, as these samples, commercially available reagents were used.

Α-FeO which is the main component of hydrous iron oxide
(OH) and γ-FeO (OH) are heated to 25
From around 0 ° C, dissociation of the bound water (2FeO (OH) →
Fe ₂O₃+ H₂O), dehydration by evaporation begins, 350
The dehydration is completed by the temperature of ℃. On the other hand, kaori, which is a clay mineral,
(Al₂Si₂O_Five(OH)_Four) Is the iron oxide hydroxide
The dissociation of the structural water (Al
₂Si₂O_Five(OH)_Four→ Al₂Si₂O₇+ 2H₂O), evaporation
Dehydration by means of water begins and is completed by 600 ° C.

In the experiment of FIG. 2, since a reagent was used as a sample, a naturally occurring goethite (α-Fe
O (OH)), hematite (γ-FeO (OH)), and kaolin (Al ₂ Si ₂ O ₅ (OH) ₄ ) may cause variations in dehydration temperature due to differences in crystallinity and structure. There is. Therefore, in order to optimize the roasting temperature, the actual limonite is roasted to obtain goethite (α-FeO (OH)), hematite (γ-FeO (OH)), and kaolin (Al).
_It is necessary to understand the dehydration status of ₂ Si ₂ O ₅ (OH) ₄ ).

In FIG. 3, 50 to 55 of actual limonite A is shown.
The measurement result of the infrared absorption spectrum when heating in the temperature range up to 0 ° C. at a heating rate of 10 ° C./min is shown. In addition,
The absorption due to α-FeO (OH) is 3130 (1 /
cm) and 906 (1 / cm), 796 (1 / c)
m), the absorption due to kaolin (Al ₂ Si ₂ O ₅ (OH) ₄ ) is 3697 (1 / cm), and 36
20 (1 / cm) respectively.

From the infrared absorption spectrum, the absorption due to α-FeO (OH), which is iron oxide hydrate, was observed at a heating temperature of 30.
It begins to decrease remarkably at 0 ° C or higher, and becomes almost undetectable at heating temperatures of 350 ° C or higher. On the other hand, the absorption due to kaolin begins to decrease at a heating temperature of 450 ° C. or higher, and is hardly detected at a heating temperature of 500 ° C. or higher.

In the present invention, the heating temperature when the iron ore containing hydrous iron oxide is roasted in a roasting furnace in advance to remove the bound water in the hydrous iron oxide is the heating temperature. The temperature is set to a temperature range higher than the dissociation temperature and lower than the dissociation temperature of bound water in kaolin.

Here, the dissociation temperature of the bound water in the hydrous iron oxide is, for example, when the measurement of the infrared absorption spectrum of the iron ore during heating as shown in FIG. 3 is used. Absorption due to α-FeO (OH) (3130
(1 / cm), 906 (1 / cm), and 796
(1 / cm)) is defined as the heating temperature at which it begins to significantly decrease, and is 300 ° C. from FIG.

The dissociation temperature of bound water in kaolin means, for example, when the infrared absorption spectrum of iron ore as shown in FIG. Absorption due to Al ₂ Si ₂ O ₅ (OH) ₄ (3697 (1 / cm) and 3620 (1 / c)
m)) is defined as the heating temperature at which
From FIG. 3, it is 500 degreeC.

The heating temperature of the roasting furnace is lower than the dissociation temperature of the bound water in the hydrous iron oxide (for example, when the infrared absorption spectrum measurement of iron ore as shown in FIG. 3 is used, In the case of less than 300 ° C.), the bound water in the hydrous iron oxide is not sufficiently reduced, and the bound water (nH ₂ O) in the ore is decomposed and evaporated during the heating process during sintering, and Since a crack occurs in the melt, the melt generated by the subsequent assimilation reaction enters the crack and the assimilation reaction proceeds rapidly, and the assimilated structure after cooling and solidification becomes a fragile structure with large pores remaining. Or decomposes bound water (nH ₂ O),
There is a problem in that extra heat energy is used to evaporate, which causes a decrease in the sintering temperature.

The heating temperature of the roasting furnace is equal to or higher than the dissociation temperature of bound water in kaolin (for example, 500 ° C. when the infrared absorption spectrum of iron ore as shown in FIG. 3 is used for heating). In the above case, the bound water in the hydrous iron oxide is sufficiently reduced, but kaolin (Al ₂ Si ₂ O ₅ (O
The bound water in H) ₄ ) is dissociated (Al ₂ Si ₂ O ₅ (OH) ₄
→ Al ₂ Si ₂ O ₇ + 2H ₂ O), evaporated and Al ₂ Si ₂ O
₇ (Al ₂ O ₃ · 2SiO ₂ ) is transformed, and the effect of improving the viscosity when water is added, which is a characteristic of kaolin (Al ₂ Si ₂ O ₅ (OH) ₄ ), is significantly reduced.

Therefore, after the iron ore containing the iron oxide hydroxide is roasted, the granulating property at the time of granulating by mixing with other sintering compounding raw materials and water is reduced, so that it is calcined by a sintering machine. There is a problem that the air permeability at the time of binding is lowered, and the productivity of the sintered ore and the product yield are lowered.

For this reason, the heating temperature for roasting in a roasting furnace is in a temperature range above the dissociation temperature of bound water in hydrous iron oxide and below the dissociation temperature of bound water in kaolin (for example, When the measurement of the infrared absorption spectrum during heating of the iron ore as shown in 3 is used, 300 ° C. or higher, 50
It is necessary to set the temperature range below 0 ° C.

In order to further improve the granulation property, the upper limit of the heating temperature when roasting in a roasting furnace is 45.
It is preferable to set the temperature as low as 0 ° C. (temperature measured by infrared absorption spectrum). Further, in order to reduce the content of bound water in hydrous iron oxide in a short time, the upper limit of the heating temperature when roasting in a roasting furnace is increased to 350 ° C. (temperature measured by infrared absorption spectrum). It is preferable to set.

As described above, by using the infrared absorption spectrum measuring method of iron ore at the time of heating, the dehydration state of bound water in hydrous iron oxide and structural water in kaolin can be grasped easily and with good accuracy. The dissociation temperature of each can be determined by, for example, a method by X-ray diffraction, a method by thermal analysis, a method of measuring water generated during sample heating,
Using the measurement method such as the nuclear magnetic resonance method, the dissociation temperature of bound water in hydrous iron oxide and the structural water in kaolin is calculated based on the relationship between the heating temperature during roasting and the measured values. May be determined.

Further, in the present invention, when roasting in a roasting furnace, the water content in the iron ore containing hydrous iron oxide is 2.0.
It shall be reduced to less than or equal to mass%. The reason for reducing the amount of water in the iron ore containing iron oxide hydroxide to 2.0% by mass or less is to decompose the bound water (nH ₂ O) in the ore during the heating process during sintering. , It is possible to prevent the occurrence of cracks in the ore due to evaporation, to suppress the assimilation reaction due to the penetration of the assimilated melt into the cracks, and to suppress the generation of residual pores in the assimilated solidification structure. This is because it is possible to obtain a sufficient effect such that the heat energy loss due to the decomposition / evaporation of bound water and the accompanying increase in the fuel consumption rate can be suppressed.

As the heat source of the roasting furnace of the present invention, a part of the waste heat of the cooler of the sintering machine may be used.

The pre-heat treatment may be performed near the sintering machine of the iron mill, or outside the iron mill, or in Yamamoto, which is a resource-holding country.

[0043]

EXAMPLE An example of an embodiment of the present invention is shown in FIG. An iron ore containing hydrous iron oxide such as limonite is charged into the roasting furnace 2 from the storage tank 1 and roasted in the roasting furnace 2 so that the combined water in the hydrous iron oxide is 2.0 mass% or less. Then, it is transferred to the iron ore storage tank 3. The iron ore containing 2.0% by mass or less of bound water in the hydrous iron oxide after roasting is taken from the iron ore storage tank 3, and the other sintering raw materials are the iron ore storage tank 4 and the auxiliary raw material tank 5, 6 into the mixer 7, after mixing and granulating with the mixer 7, they are charged into the sintering machine 10 via the surge hopper 8 and the drum feeder 9.

After igniting the carbonaceous material in the upper layer of the sintered packed layer by the ignition furnace 10, air is sucked from the upper side to the lower side through the main exhaust gas duct 13 so that the burning point of the sintering raw material is changed from the upper side. While moving downward, it is heated and fired to form a predetermined sintered zone 11 and discharged as a sintered ore 12.

The heat source of the roasting furnace 2 is best to utilize the waste heat of the cooler 14 for cooling the sinter 12, but the other heat source 15 is used to raise the temperature of the roasting furnace 2 to a higher temperature. It is also possible to do so.

Next, the effects of the present invention will be described by comparing the respective effects in the invention example and the comparative example carried out under the conditions out of the range defined by the present invention.

Table 1 shows the proportion of the blended raw materials used as sintering raw materials in the invention examples and comparative examples, and Table 2 shows the heating temperature during roasting of limonite in the inventive examples and comparative examples and the water content of limonite before and after roasting. (Bound water content in hydrous iron oxide) and kaolin content, and powder coke addition amount (external number of sintering raw material). Further, in Table 3, granulation property and sintering in the invention example and the comparative example. The evaluation results of the reducibility and sinter ore reduction powdering property are shown.

The water content of limonite before and after roasting (content of bound water in hydrous iron oxide) is JIS M8211.
Based on the "method for determining combined chemical water in iron ore", the sample ore was previously heated to 105 ° C in a dry nitrogen stream to remove hygroscopic water, and subsequently heated to 950 ° C in a dry nitrogen stream, At this time, the liberated bound water was absorbed in a mixed solution of ethylene glycol / methanol and electrically titrated with a Karl Fischer reagent standard solution, and the amount was defined as the water content (mass%).

The kaolin content in the limonite before and after roasting was determined from the infrared absorption spectrum measurement results as follows. That is, using a commercially available reagent kaolin, infrared absorption spectra were measured in different amounts of kaolin in advance, a calibration curve was prepared from the absorption intensity due to OH derived from kaolin, and then, before and after roasting. Infrared absorption spectrum of the sample ore (limonite) of No. 2 was measured, and the absorption intensity of OH derived from kaolin in the ore was also obtained. Based on this absorption intensity, a calibration curve of the amount of kaolin and the absorption intensity obtained in advance was used. ,
It was calculated by converting the kaolin content (mass%) in the sample ore (limonite).

The evaluation of the granulation property in Table 3 was carried out based on the measurement of the granulation yield and the strength of the granulated product. The granulation yield (pseudo-granulation index: GI _0.5 (%)) was calculated from the following formula.

GI _0.5 = {(AB) / A} × 100 A: Mixing ratio of true particles of 0.5 mm or less B: Mixing ratio of pseudo particles of 0.5 mm or less The strength of the granulated product is GI _0.5 . It was evaluated using 83 or more as o, 78 to 82 as Δ, and 77 or less as x.

The sinterability was evaluated based on the measurement of granulation temperature, air permeability, productivity, and product yield. Regarding the sintering temperature, 1250 to 1400 ° C. was “good”, lower temperature was “low”, and higher temperature was “high”. Regarding the sintering temperature, there is local "unevenness", so the structure was observed after sintering and used as a reference for evaluation.

The breathability of the JPU (Japanease Permeabili
ty Unit).

JPU = (F / A) (h / s) ^0.6 F: Flow rate (Nm ³ / min) A: Suction area (m ² ) h: Charge layer thickness (m) s: Negative pressure (mH ₂ O) ) Since the JPU differs depending on the equipment, it is tested using a 50 kg pan tester, and JPU 13 or higher is ○, 9-12 is Δ,
8 or less was designated as x.

The quality of the sintered ore was evaluated by the reduction powdering property. The reduction pulverization property estimates the pulverization property of the sinter in the blast furnace in a relatively low temperature region.
After reducing in a reducing atmosphere of 0% N ₂ at 550 ° C. for 30 minutes, it is put into a predetermined rotation tester, rotated at a predetermined rotation speed, sieved with a predetermined sieving, and evaluated by mass% of each section. . The calculation formula is shown below.

RDI (%) = (W3 / W2) × 100 W2: Mass of sample loaded in rotary tester (g) W3: Mass of sample of 3 mm or less after sieving (g) Invention Example No. Nos. 1 to 5 were good in both granulation property, sinterability, and reduction powdering property of sinter, but Comparative Example No. carried out under conditions outside the range of the conditions specified in the present invention. ．
In Nos. 6 to 13, any one of the evaluation of the granulation property, the sinterability, and the reduction and pulverization property of the sintered ore was lower than that of the invention example.

That is, in Comparative Example 6, the moisture content is out of the range defined by the present invention because it is not roasted, and although the granulation property can be secured, the sintering temperature is low, the air permeability, The productivity and product yield were low. Comparative Example 7
Has increased the amount of coke powder in order to improve the decrease in the sintering temperature, but a local increase in temperature is observed, the air permeability is further deteriorated, and the productivity is poor. Since Comparative Examples 8, 9, 10 and 11 have low roasting temperatures, Comparative Examples 6 and 7
The result is similar to.

Although the iron oxide hydroxide was liable to contain water, it did not contribute to the granulation property, and the granulation yield tended to be slightly lower than in the Examples. In Comparative Examples 12 and 13, the kaolin is deteriorated because the roasting temperature is too high, and the granulation property is deteriorated. As a result, the air permeability, the productivity, the product yield are lowered, and the reduced powdering property is reduced. It got worse.

[0059]

[Table 1]

[Table 2]

[Table 3]

[0060]

As described above, according to the present invention, iron ore containing hydrous iron oxide such as limonite is roasted in advance by a roasting machine, then mixed and granulated and sintered by a sintering machine. In the method of producing, the content of bound water in iron oxide can be reduced without lowering the granulation property of iron ore after roasting, and the amount of sinter in the case of using a large amount of limonite as a sintering raw material It is possible to provide a method for producing a sinter that can improve productivity and product yield and improve sinter quality such as cold strength and resistance to reduction pulverization.

[Brief description of drawings]

FIG. 1 is a schematic view of a sinter production process showing an example of an embodiment of the present invention.

FIG. 2 is a hydrous oxide, goethite (α-FeO (O
H)) and hematite (γ-FeO (OH)) and clay mineral kaolin (Al ₂ Si ₂ O ₅ (OH) ₄ ) at a heating temperature of 50 to 600 ° C. T
G) is shown.

FIG. 3 is a diagram showing measurement results of infrared absorption spectra when limonite A is heated.

[Explanation of symbols]

1 ... Storage tank 2… Roasting furnace 3 ... Iron ore storage tank 4 ... Iron ore storage tank 5 ... Sub-material tank 6 ... Sub-material tank 7 ... mixer 8 ... Surge hopper 9 ... Drum feeder 10 ... Ignition furnace 11 ... Sintered zone 12 ... Sintered ore 13 ... Main exhaust gas duct 14 ... Cooler 15 ... Other heat sources

Continued front page    (72) Inventor Imafuku Muneyuki             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division (72) Inventor Kouki Tanaka             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division (72) Inventor Kouji Saito             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division (72) Inventor Shunichi Hayashi             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division (72) Inventor Koji Kanahashi             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division (72) Inventor Jun Okazaki             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division (72) Inventor Yozo Hosoya             20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel shares             Company Technology Development Division F-term (reference) 4K001 AA10 BA02 CA11 CA32 CA37                       CA45

Claims (6)

[Claims] 1. An iron ore containing iron oxide hydroxide is roasted in a roasting furnace in advance to remove bound water in the iron oxide hydroxide, and then mixed and granulated with other sintering raw materials and sintered. In a method for producing a sinter that is charged into a machine and sintered, the heating temperature at the time of roasting is equal to or higher than the dissociation temperature of bound water in hydrous iron oxide,
A method for producing a sinter, comprising setting a temperature range below a dissociation temperature of structural water in a clay mineral. 2. The dissociation temperature of the bound water in the hydrous iron oxide and the dissociation temperature of the structural water in the clay mineral are determined by the heating temperature during roasting and the infrared absorption spectrum after roasting at the heating temperature. The method for producing a sinter according to claim 1, which is determined on the basis of a relationship between an absorption intensity resulting from bound water in the iron oxide hydroxide and an absorption intensity resulting from structural water in the clay mineral. . 3. The absorption intensity resulting from bound water in the hydrous iron oxide is 3600 to 2800 in the infrared absorption spectrum.
The absorption intensity, which is measured in the wave number range of (1 / cm) and is due to the structural water in the clay mineral, is 3 in the infrared absorption spectrum.
The method for producing a sinter according to claim 2, wherein the sinter is measured in a wave number range of 800 to 3600 (1 / cm). 4. The baking according to any one of claims 1 to 3, wherein the amount of water in the iron ore containing hydrous iron oxide is reduced to 2.0% by mass or less by the roasting. Manufacturing method of calculus. 5. The sintered ore according to claim 1, wherein a part of waste heat of a cooler of the sintering machine is used as a heat source during the roasting. Production method. 6. The method for producing a sintered ore according to claim 1, wherein the clay mineral is kaolin.