WO1996009415A1 - Sintered ore manufacturing method using high crystal water iron ore as raw material - Google Patents

Abstract

In a method of manufacturing a sintered ore of a high strength at a high yield by using a geothite ore (1) (iron ore A) containing not less than 3 % of crystal water, the geothite ore (1) is compounded at 60 % with a main raw material, and a return ore (2) which is 1/4 of the geothite ore is added to the resultant mixture. The product thus obtained is subjected to a mixing and pseudogranulation operation using a granulating machine (4), and the resultant pseudoparticles are mixed with raw compounding materials (3), such as low crystal water ore, limestone, silica rock and cokes in a drum mixer (5) to obtain a raw sintered material.

Description

 Description Manufacturing method for sinter from high-crystalline iron ore

 The present invention relates to a method for producing sintered ore for a blast furnace by using, as a part of a raw material, highly crystalline hydroiron ore having a crystallization water content of 3% or more. Background art

 To operate a blast furnace stably and efficiently, high-quality sinter is required, and qualities such as cold strength, reducibility, and resistance to powdering are strictly controlled. In addition, the yield and productivity of sintered mineral products are also important management items in order to reduce the production cost of sintered ore.

And such a sinter is generally manufactured by the following method. First, an iron oxide ore of about 1 Omm or less is mixed with a Ca 0 -containing auxiliary material such as limestone, a Si〇 ₂ -containing auxiliary material such as silica stone and serpentine, and a solid fuel such as coke. Granulate by adding water. The granulated material is charged to a suitable thickness on a moving pallet of a Dwyroid type sintering machine, and the solid fuel on the surface layer is ignited. After ignition, the solid fuel is burned while sucking air downward, and the heat of combustion sinters the blended raw materials to form a sintered cake. This sintered cake is crushed and sized to obtain a sintered ore having a certain particle size or more. Sinter ore with a particle size less than a certain size (usually -5 mm) is called remineralization and is returned to the raw material of sinter.

Conventionally, mainly hematite as the iron raw material of sintered ore _{(Fe 2 0 3: Hemat ite} ) and magnetite _{(Fe 3 0,: Ma gne} tite) and have been used. However, as the recent production amount of iron ore quality is reduced, goethite (F e 2 〇 ₃ · _{ηΗ 2} ○: Gesai Doo: Go e th ite) and to contain a large amount Iron ore usage tends to increase gradually. Goethite contains a large amount of water of crystallization and is characterized by high porosity at room temperature and after heating.When used in large quantities as a sintering raw material, not only does the strength of the product decrease, but also the yield and yield increase. There was a problem that productivity dropped.

The reason why such a problem occurs is considered as follows. That is, in the sintering process, when CaO and F e ₂ 0 ₃ produces a melt calcium ferrite reacts, porosity after heating iron ore containing a large amount of Gesai I and other iron ore for very high compared, is highly reactive, the higher the Fe ₂ 0 ₃ concentration in the melt. This increases the liquidus temperature and reduces the time required for pore rearrangement. As a result, the rearrangement of pores is hindered, the proportion of coarse pores of about 1 to 5 mm increases, and the strength and yield of sinter decrease.

As described above, the use of iron ore containing high crystal water, for example, iron ore containing a large amount of goethite as a sintering raw material causes many problems. Therefore, various techniques have been proposed to use these iron ores in large quantities. For example, by Japanese Patent Publication No. Hei 3 -47927 formulating auxiliary materials containing MgO-S i 0 ₂ having a predetermined ratio to the periphery of these iron ore, Fe ₂ 0 ₃ in the melt of calcium ferritic There is disclosed a method for preventing a large amount of from melting. In this way, when using the iron ore containing much Gesai Bok large amount, MgO-S i 0 ₂ must be considerably Many formulation auxiliary materials containing, the manufacturing cost becomes high as the raw material to be sintered . The method further in order to perform complete coverage of the sub feedstock containing MgO-S i 0 _2, it is necessary to add the solid fuel, the production cost by increasing the amount of heat consumed is, there is a problem that the even higher Was. Further, MgO-S i 0 ₂ content since the ratio of the auxiliary material and iron ore you containing high water of crystallization has been specified, the blending ratio of the iron ore containing high water of crystallization exceeds 30%, MgO - a problem that slag ratio in S i 0 ₂ have the need to blend a large amount blast furnace is increased occurs. On the other hand, Japanese Unexamined Patent Publication No. 3-107207 discloses that iron ore containing a large amount of goethite is heated at a temperature of 1200 ° C. or more for a certain period of time to densify the iron ore. reduce the porosity, a method to prevent the F e ₂ 0 ₃ is melted in a large amount is disclosed in the melt of calcium full We write system. In this method, since the raw material must be subjected to heat treatment at a high temperature in advance, there is a problem that the production cost is increased due to an increase in heat consumption.

 The present invention has been made in view of the above-mentioned phenomena, and its purpose is to use a large amount of iron ore containing high crystal water, such as goethite, as a sintering raw material. It is an object of the present invention to provide a method for producing sinter with a high yield without problems such as an increase in production, a decrease in productivity, and a significant increase in auxiliary materials. Disclosure of the invention

 SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in producing a sintered ore using a high-crystallite iron ore as a raw material, the high-crystallite iron ore is mixed with returned ore, and granulated. After that, it is a method for producing a sintered ore using a high crystalline water ore as a raw material, characterized in that it is blended with another raw material and then sintered.

 More specifically, high crystallite iron ore with a crystallization water content of 3% or more and returned ore with a size of 5 mm or less are mixed at a ratio of high crystallite iron ore at a ratio of 1 to 5 or more. This is a method for producing a sintered ore using highly crystalline hydroiron ore as a raw material, after granulation and mixing with another raw material for sintering. In this case, it is preferable to use returned ore having a Ca0 content of 8 to 15% by weight as the returned ore, and it is preferable that the returned ore has a smaller particle size, for example, 1 mm or less. It is suitable. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic explanatory diagram of a production process of a sintering raw material. Fig. 2 is a graph showing the relationship between the mixing ratio of iron ore A mainly composed of goethite and the yield.

 Figure 3 is a graph showing the pore size distribution of the sintered cake when the mixing ratio of iron ore A was changed.

FIG. 4 is a graph showing the relationship between the mixing ratio of iron ore A and the moving distance of the melt. FIG. 5 is a graph showing the relationship between the moving distance of the melt and the pore diameter distribution index. 6 is a state diagram of the C a O- F e ₂ 0 ₃ system.

 FIG. 7 is an explanatory diagram of the experimental method of the melting depth.

 FIG. 8 is a graph showing the relationship between the porosity of iron ore and the melting depth.

 FIG. 9 is an explanatory diagram of the experimental method of the melting depth.

 FIG. 10 is a graph showing the relationship between the C a O concentration in the tablet and the melting depth.

 FIG. 11 is an explanatory view of the experimental method of the melting depth.

 Figure 12 is a graph showing the effect of the returned ore coating on the melting depth of iron ore.

 FIG. 13 is a flow sheet of the method for returning and covering coating in Example 2. FIG. 14 is a graph showing experimental results in Example 2. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, the configuration and operation of the present invention will be described with the progress of experiments.

 First, the present inventors have developed a high-crystal water iron ore (hereinafter referred to as iron ore) mainly composed of game sites.

A) (abbreviated as A) was examined for changes in sinter ore retention when the mixing ratio was increased. Figure 2 shows the results. From this, it was found that the use of a large amount of iron ore A greatly reduced the sinter ore retention.

Figure 3 shows the results of investigation of the pore size distribution of the sintered cake when the iron ore A content was 0% and 40%. Figure 3 shows the pore diameter D (mm) on the vertical axis and the pore diameter on the horizontal axis. The log ratio R {%) of stomatal or higher is plotted in log-logarithm. From Fig. 3, it was found that as the mixing ratio of iron ore A was increased, the proportion of coarse pores of about 1 mm to 5 mm increased.

 Here, the yield of the sinter has a high correlation with the strength of the sinter cake, and the yield of the sinter can be estimated from the strength of the sinter cake using the equations (1) to (4).

Y = K · σ _s ⁿ … (1)

 σ s = σ o * e x p i.- c * P) ― (2)

^{σ o = S · m T ·} exp (- U · Q) - (3)

c = h, · | 3 + h ₂ … (4)

 Y: Sinter ore yield (%)

 os: Tensile strength of sintered cake (MPa)

 σ. ： Substrate strength of sintered cake (MPa)

 P: Porosity of sintered cake (1)

 m: Calcium fluoride content in the sintered cake

 Q: Calcium silicate content in sintered cake

 β: Pore size distribution index (slope of graph in Fig. 3)

Κ, n, S, Τ, U, h,, h ₂ : Constant

 The pore size distribution index (/ 3) is the slope of the graph in Fig. 3 and is a value unique to each sintered cake. Using this, c in equation (2) can be obtained from equation (4).

Using the measured values of the mineral composition, porosity, and pore size distribution index when the mixing ratio of iron ore A was increased from 0% to 40%, and by using the above formulas (1) to (4), the yield was determined for each factor. As a result of calculating the change, it was estimated that about 80% of the decrease in yield was due to the decrease in the pore size distribution index. From the above, it is considered that the decrease in yield due to iron ore A is caused by changes in the pore structure represented by the pore size distribution. Therefore, the change in the pore structure with the increase in iron ore A is caused by the flow of the melt that governs the coalescence of the pores. Considering that there is a close relationship with the mobility, we measured the movement distance of the melt as an index showing the properties of the melt and investigated the effect of iron ore A on the fluidity of the melt.

 Figure 4 shows the results of measuring the moving distance of the melt using SrO as a tracer under the condition of constant heat input. From Fig. 4, it was found that the movement distance of the melt decreased with the increase of iron ore A.

 Fig. 5 shows the relationship between the moving distance of the melt and the pore size distribution index. The pore size distribution index decreases as the melt travel distance decreases. This is considered to be due to the fact that the coalescence of the pores was inhibited by the decrease in the fluidity of the melt.

Table 1 shows the composition of the calcium fluoride-based melt when the mixing ratio of iron ore A was increased from 0% to 40%. From this, as the blending ratio of the iron ore A increases, it has been found that F e ₂ 0 ₃ ¾ of calcium ferrite in the melt is high summer.

This force, et al, the moving distance of the melt with increasing content ratio of the iron ore A that decreases, from the C a 0- F e ₂ 0 ₃ phase diagram of FIG. 6, F e ₂ 0 ₃ It is considered that the liquidus temperature increases as the temperature increases, and the transit time of the melt decreases.

Reduction in the yield with the previous results the increase in iron ore A is believed to be due to the increase of F ez 0 ₃ concentration in the melt. Therefore, the melt composition was considered to be closely related to the reactivity between iron ore and quicklime, and the experiment shown in Fig. 7 was performed.

As shown in Fig. 7 (a), a sample in which limestone 12 of 8 mm Φ x 8 mm x 8 mm in height was placed on iron ore 11 of 16 mm × 16 mm × 10 mm in height was placed. , 130, and 2, respectively, and then cooled with water. After cooling, the central part of the sample was cut, and limestone 12 penetrated into 11 of the iron ore as shown in Fig. 7 (b). This cut surface was polished, and the cross section was photographed with a 10 × projector, and the fusion depth 14 shown in FIG. 7 (b) was obtained. Figure 8 shows the effect of the porosity of iron ore 11 on the melting depth 14 described above. Curves 21, 22 and 23 show the iron ores with porosity of 11.0%, 22.8% and 32.4%, respectively. As is evident from Fig. 8, as the porosity of the iron ore increases, the melting depth increases, indicating that the porosity of the iron ore has a large effect on the reaction rate of the iron ore.

 Next, as shown in Fig. 9, the place where quicklime 12 was placed so far, the CaO concentration was 100.0%, 62.0%, 42.0%, 22.0% as shown in Table 2. The same experiment as in Fig. 7 was carried out with the tablet 15 changed.

 Fig. 10 shows the effect of the C a 0 Ban degree in the tablet 15 on the melting depth 14. In Fig. 10, the porosity (11.0%) and the retention time (4 minutes) of iron ore 11 are constant. As is evident from FIG. 10, it was found that the melting depth decreased as the 'Ca0 concentration in the tablet 15 decreased.

Furthermore, since there is a Ca0 concentration gradient at the reaction interface between iron ore and quick lime, the reaction between iron ore and quick lime is considered to be diffusion-limited.However, when the diffusion coefficient is calculated backward from Fick's law, The diffusion coefficient calculated from is larger than that of the previously reported diffusion coefficient by 10 ³ to: L. This is thought to be because the generated melt penetrated the pores and cracks in the iron ore, and the surface diffusion was dominant rather than the normal bulk diffusion.

Therefore, as increasing the blending ratio of the iron ore A, it is considered that Fe ₂ 0 ₃濂度in calcium Hue Rye bets melt is high summer.

This is the actual sintering exhibition in CaO is because has been insufficient for Fe ₂ 0 _3, in the sintering process, CaO and Fe ₂ 0 ₃ produces a melt calcium Blow Lee Bok system reacts when the porosity after heating iron ore a is other for very high compared to iron ore (2-3 times), it is promoted surface diffusion of Fe ₂ 0 ₃ melt depth increases It is considered that the reaction amount increases. Therefore, iron ore A When blending a large amount, it is considered important to suppress the reaction that generates an excessive amount of melt.

 So far, the melting depth was measured by the method shown in Fig. 7, but as shown in Fig. 11, between the quicklime 12 and the iron ore 11, the returned ore 1 with the composition shown in Table 3 was obtained. An experiment in which 3 was sandwiched was performed. In FIG. 12, curve 24 shows the results of the experiment shown in FIG. 7 (a), and curve 25 shows the results of the experiment shown in FIG. According to Fig. 12, the depth of melting can be suppressed by sandwiching the returned ore 13 between the quicklime 12 and the iron ore 11. This is thought to be due to the fact that the melting reaction between iron ore and limestone is a reaction). The driving force is the concentration gradient of C a 0 in S. In other words, it suggests that the melting reaction of iron ore can be suppressed by coating iron ore with a return of Ca 0% lower than that of limestone in advance.

 The present invention has been made as a result of conducting research based on these experimental results.

C a O ¾ of already low to cover the periphery of the iron ore A with return ores reacted with F e ₂ 0 _3, to suppress a rapid reaction between the iron ore A and quicklime, calcium off We write system of the melt by reducing the F e ₂ 0 ₃ concentration in, increasing the time required for rearrangement of the pores, without increasing the amount of solid fuel, in which succeeded in enhancing the yield of the sintered ore .

 The fineness of the ore returned to cover iron ore A must be fine and should be 5 mm or less. This is because fine grains are more likely to adhere to the periphery of iron ore A, and preferably have a grain size of l mm or less. The amount of ore mixed with iron ore A shall be 0.2 to 1 part by weight based on 1 part by weight of iron ore A. If the amount is less than 0.2 parts by weight, the ore return is not enough to cover the surface of iron ore A. If the amount exceeds 1 part by weight, the effect is saturated and the balance is not appropriate due to the quantitative balance. by.

The returned ore used was a returned ore having a CaO content of 8 to 15% by weight. If the Ca0 content is less than 8% by weight, the Ca0 content is too low, which hinders the melting reaction. If it exceeds 15% by weight, the melting reaction is suppressed. This is because the advantage of adding the return ore is lost.

 Hereinafter, the present invention will be described specifically with reference to examples. Hereinafter, the raw material mainly composed of iron-containing raw material is called the main raw material, the raw material added with limestone and silica stone is called the new raw material, and the raw material added with returned or coke is called the mixed raw material. (Example 1)

 Table 4 shows the chemical composition of iron ore A used in the experiment. The iron ore A is an iron ore from Australia with an arithmetic mean diameter of 3.1 mm and a water content of crystallization of 8.9%. This iron ore A is blended according to the flow shown in FIG. In FIG. 1, 1 indicates iron ore A, 2 indicates returned ore, 3 indicates the remaining sintering raw material, 4 indicates a dish granulator, and 5 indicates a drum mixer.

 60% iron ore A (iron ore 1) is blended with the main raw material.Returned ore 2 is added to 1/4 of iron ore A and mixed with iron ore A using a dish granulator 4. Pseudo-granulated. These pseudo particles were mixed in a drum mixer 5 with the remaining compounding raw materials 3 (iron ore containing low crystal water, limestone, silica stone, and coke) to obtain sintering raw materials.

This was placed in a sintering test pan having a diameter of 300 mm and a height of 400 mm, and fired at a flow rate of 1.2 Nm ³ / min while sucking air. The resulting sintered cake was heated to a height of 2 m. Then, it was dropped once, and the yield was calculated based on the weight ratio of 1 Omm or more at that time. Figure 2 shows the results. However, Figure 2 C a 0 content of the sintered in the raw material Te smell (9. δ wt%), S i 0 2 content (5. 0 wt%), to the coke amount (3. 5 wt%) It was constant. As shown in Fig. 2, when iron ore A was blended at 60%, the yield was 66.3% in the conventional method, and it was 69.5% in the example. As is evident from Fig. 2, by adding ore return around iron ore A, it is possible to produce high-quality sintered ore with good yield without increasing the production cost. Was.

 (Example 2)

 Table 5 shows the chemical composition of iron ore A and the returned ore used in the experiment. Iron Ore A is an iron ore from Australia with an arithmetic mean diameter of 3. Omm and a crystallization water content of 8.4%. This iron ore A is blended according to the flow of FIG. In Fig. 9, 1 indicates iron ore A, 2 indicates returned ore, 3 indicates the remaining sintering raw material, 5 indicates a drum mixer, and 6 indicates iron ore A and a pre-granulated product of returned ore.

 Iron ore A (iron ore 1) was blended at 50% with the main raw material. Returned ore was added only to 1Z4 of iron ore A, and it was mixed with iron ore A using a drum mixer 5 and granulated. The iron ore A and the preliminarily returned ore granulated product 6 were once transported to the raw material yard, then received in a sintering plant, mixed with the remaining sintering raw material 3, and granulated to obtain a sintering raw material.

The experiment was performed using an actual sintering machine, and the production rate, yield, and RI are shown in Fig. 10 in comparison with the conventional method. 0. The production rate by pregranulated iron ore A with return ores 06 (tZh. M ^2), yield 1. 7% was able to be 2. improvement of 2% JIS-RI.

table 1

Table 2

Table 3

表 4

Table 4

T. F e CW A 1 ₂ 0 ₃ S i 0 Iron ore A 58.6 8,9 1.2 5.01 Return 55.4 0.0 1.2 5.54

Table 5

F e CW A 12 0 ₃ S i 0 Iron ore A 57.4 8.4 2.51 5.03 Return 55.4 0.0 1.55 5.54 Industrial applicability

 ADVANTAGE OF THE INVENTION According to this invention, in the manufacture of the sintered ore using a high crystallite iron ore as a part of the raw material, it is possible to prevent a decrease in the strength of the sintered cake, and prevent a decrease in the yield and productivity. Therefore, there is an effect that it contributes to the effective use of iron ore resources.

Claims

The scope of the claims 1. When producing sinter using high-crystal water iron ore as a part of raw material, the high-crystal water iron ore is mixed with returned ore, granulated, and then mixed with other raw materials and sintered. A method for producing a sintered ore using a high crystallite iron ore as a raw material.  2. After mixing and granulating high-crystal water iron ore with a crystallization water content of 3% or more and returned ore with a diameter of 5 mm or less at a ratio of returned high-crystal water iron ore of 15 or more A method for producing sintered ore using a high crystallite ore as a raw material, wherein the sintered ore is mixed with another raw material and sintered.  3. The method of claim 2, wherein the returned ore has a Ca0 content of 8 to 15% by weight.  4. The method according to claim 2, wherein the returned ore has a particle size of 1 mm or less.