WO1993016203A1

WO1993016203A1 - Iron-making sintered ore produced from pisolitic iron ore and production thereof

Info

Publication number: WO1993016203A1
Application number: PCT/JP1993/000184
Authority: WO
Inventors: Ukihiro Hida; Jun Okazaki; Yozo Hosotani
Original assignee: Nippon Steel Corporation
Priority date: 1992-02-13
Filing date: 1993-02-12
Publication date: 1993-08-19
Also published as: CN1036210C; AU656060B2; CN1077752A; AU3574393A; TW232031B; KR960010579B1

Abstract

An iron-making sintered ore having a cross section wherein at least 80 % of a solid part except for non fused residues of the sintering materials other than pisolitic iron ore is composed of a densified pisolitic iron ore enclosed by fine calcium ferrite with a width of 10 νm or less, or of hematite particles and calcium ferrite which bonds the hematite particles together while holding traces of the pisolitic iron ore, or of a mixture thereof. The production process comprises sintering iron-containing starting material such as iron ore, carbonaceous material, water, and the like in a sintering machine by using 40-70 mass % of pisolitic iron ore and a high-grade iron or containing 1.5 mass % or less of SiO2 as the iron-containing starting material other than returns.

Description

Description Sinter for iron-making from pisolite iron ore and its production method [Technical field]

TECHNICAL FIELD The present invention relates to a sintered ore for blast furnace pig iron making using pisolite iron ore as a raw material and a method for producing the same.

(Background technology)

Sinter ore, a major raw material of the blast furnace iron making method, which is a representative of iron making, is generally produced as follows. First, limestone about l Omm less iron ore fines, Doromai Doo, (referred to as CaO based Fukuhara fees) containing CaO auxiliary materials, such as converter slag, serpentine, silica, including S i 0 ₂ such as peridotite sub (referred to as S i 0 ₂ based auxiliary raw material) material, and coke powder, carbonaceous materials such as anthracite, further mixed with an appropriate amount of water, granulated. The quasi-granulated compounding material (pseudo-particles) is charged to a height of about 500 mm on a grate-moving sintering pallet, and the carbon material on the surface of the packed bed is ignited. . The carbon material is burned while sucking air downward, and the blended raw materials are sintered by the combustion heat generated at that time.The resulting sintered cake is crushed and sized to form a 3 to 5 mm The particles are charged into a blast furnace as a product sinter. In addition, sinters of powder unsuitable as blast furnace charging raw materials are called returned ore and returned as raw materials for sinter.

To operate a blast furnace stably and efficiently, high-quality sinter is required. Quality such as cold strength, reducibility, and powdering resistance is strictly controlled. Also, from the aspect of sinter production cost, high yield (sinter ore / sinter cake) is required.

Looking at the world's iron ore resources, high-quality hematite ore has been With the current production continuing, major mines are expected to be exhausted as early as 2000. On the other hand, Si 0 ₂ classified as Piso Lai preparative iron ore into one of iron ore is from 4.5 to 6% of the iron ore. The representative is Robe R iver of Australia, Yandi Kusina

(Yand i coo ji na). The reserves of these iron ore deposits are enormous, and the low-grade parts (ratio to earth) to be removed for mining are small, so mining costs are low and the supply is stable. Therefore, if a large amount of use of this ore, as well as economic effects such as costs reduction, there is a great significance, such as effective utilization of resources, but to the ore Matthew Doo (Fe ₂ 0 ₃₎ gate the particles one since the site _{_{_{(Fe 2 0 3 · H 2}}} 0) is the so-called fish-egg-like structure that surrounds, are having some problems. That is, the decomposition of the bound water occurs during the heating process, and a large crack is selectively generated at the gate site. As a result, the ore becomes vulnerable first. Next, when a melt is generated by the reaction between the auxiliary material and the iron ore, the melt rapidly penetrates into the cracks, and large pores are formed in the melt, reducing the strength of the sintered body. This will reduce the yield and cold strength of the sintering operation. Also, assimilation department

(The part where the melt and the ore have reacted) becomes small granular matite particles and glassy silicate, and the low-temperature reduction powdering resistance deteriorates. For this reason, it is currently impossible to increase the amount of iron ore used. As mentioned earlier, the development of a sintering method using large amounts of pisolite iron ore is significant from the viewpoint of effective use of resources and cost reduction.

The basis of measures against pisolite iron ore is to suppress the rapid penetration of large amounts of melt into the cracks. As a method of suppressing the rapid infiltration of the melt, the inventors have proposed a protective layer having a special composition on the surface around the ore as disclosed in Japanese Patent Application Nos. 1-184047 and 2-115730. A viscous material as disclosed in Japanese Patent Application Nos. 3-146481 and 3-303854. We have clarified a method for forming a melt having a high melting point. However, these methods have the drawback that special auxiliary raw materials, as well as pre-granulation equipment or special raw material segregation charging equipment for the sintering machine are required.

Therefore, the present inventors thought that if the momentary amount of the melt existing around the pisolite iron ore could be limited to a very small amount, the infiltration of the melt could be suppressed, and a number of basic studies were conducted on the conditions for that. As a method of the present invention applicable to existing sintering machines.

That is, an object of the present invention is to provide an excellent quality sinter using iron ore, particularly pisolite iron ore, which is inexpensive and rich in resources.

Another object of the present invention is to produce excellent quality sinter using the above iron ores without requiring special equipment.

[Configuration of the invention]

To achieve the above object, the present invention is as an iron-containing materials other than return ores. Pisorai preparative iron ore and S i 0 ₂ content of 1.5 mass% or less (all of the following percentages indicating the mass%) High By using high-grade iron ore and sintering an iron-containing raw material containing 40 to 70% of pisolite iron ore together with auxiliary materials, carbonaceous material, water, etc. by a sintering machine at a temperature of 1200 ° C or more, In the cross section of the sinter, 80% or more of the solid portion excluding the unmelted residue of the sintering raw material other than the piezolite iron ore: 1) A fine calcite with a width of 10 zm or less (1) Surrounding ferrite, (2) Consisting of hematite particles and traces of pisolite iron ore and composed of calcium ferrite that binds the hematite particles, or (3) Granularite Hematite particles mixed with calcium carbonate Ones or they ①, ②, it is intended to provide Hisage the steel for sintered ore composed of a mixed structure of ③. As the iron-containing materials other than return ores to be provided to the sintering means, Si0 ₂ content of less 60% of 1.5 or less of high-grade iron ore Al _₂ 0 ₃ ZSi0 ₂ of mass ratio of 0.3 or less of iron ore in it it is also possible to substitute a was even or, the Pisorai preparative iron ore, it is also possible to blend a slip metering of high-grade iron ore and low A1 ₂ 0 ₃ iron ore to be 80% or more.

The sintered ore obtained in this way has the same excellent yield and quality as hematite ore, which has been conventionally regarded as good quality.

The percentages of the following chemical components are all mass%.

[Brief description of drawings]

Figure 1 is a sinter iron ore in a single brand basicity Si0 _2% and sintered ore in width 10 m or less of in the iron ore in the sinter produced in by Uni pan to be 1.6-2.2 It is a figure which shows the relationship of the ratio of a fine calcium carbonate slag.

Figure 2 is Si0 ₂ is A1 _₂ 0 ₃ ZSi0 ₂ iron ore in the sintering ore basicity of sintered ore is produced in the pot so that the 1,6 to 2.2 to 1.5% or more ores single stocks FIG. 4 is a graph showing the relationship between the ratio and the ratio of fine calcium carbonate and slag having a width of 10 / m or less in sinter.

FIG. 3 is a view showing a microstructure of the sintered ore of the present invention.

FIG. 4 is a view showing another microstructure of the sintered ore of the present invention.

FIG. 5 is a diagram showing another microstructure of the sintered ore of the present invention.

FIG. 6 is a diagram showing a microstructure of a conventional sintered ore.

Figure 7 is a Pisorai bets iron ore and Si0 ₂ sintering pot test results of material consisting of 1.5% or less of iron ore, proportions and finished product yield of Pisorai bets iron ore accounts for both iron ore, sinter It is a figure which shows the relationship of JIS drop strength.

In FIG. 8 is Shoyuinabe test results, the ratio of Pisorai preparative iron ore in the raw materials Pisorai bets iron ore and Si0 ₂ is comprised of more than 1.5% iron ore 40 % Or to 70%, further the Si0 ₂ is the algebraic upgrade rate and finished products yield when a portion of 1.5% or less of iron ore Al _₂ 0 ₃ ZSi0 ₂ mass ratio was replaced with 0.3 or less iron ore, baked It is a figure which shows the relationship of the JIS fall strength of the condensate. In Figure 9 is Shoyuinabe test results, a 40% or 70% the proportion of Pisorai preparative iron ore in the raw materials Pisorai bets iron ore and Si0 ₂ is comprised of 1.5% iron ore, then its Si0 ₂ 1.5 % or less of 60% iron ore replace Al _₂ 0 ₃ / Si0 ₂ weight ratio of 0.3 or less of iron ore, larger iron ore than 0.3 part Α 1 _₂ 0 ₃ ^ ί0 ₂ mass ratio thereof starting material FIG. 6 is a graph showing the relationship between the substitution rate, the product yield, and the JIS drop strength of sinter when sintering is performed.

[Best mode for carrying out the invention]

Hereinafter, the best mode for carrying out the present invention will be described in detail. First, the basic principle of the present invention will be described.

The feature of the method of the present invention is that the existing melt that changes every moment is kept to a very small amount as described above. The basic principle is that it promotes the generation of calcium ferrite (needle or plate with a width of 10 micron or less) that begins to be formed by the reaction between solid and liquid at approximately 1,200 ° C during the heating stage of the sintering process. It is. The cull shoe © beam Blow wells is generated as soon as the high CaOZSi0 ₂ of the melt occurs, a so-called melt generating rate-limiting, the melt amount that is actually present is very small. The present invention pursues the properties of the ore and the formation of this calcium ferrite.

First, the present inventors have conducted single stocks sintering tests was adjusted to iron ore and limestone CaOZSi0 ₂ is usually within a range of sintered ore 1.6 to 2.2, 20 discussions section of the front and rear of the baked ore particles Was polished, and the proportion of fine calcium ferrite with a width of 10 m or less on the cross section was quantified using an optical microscope equipped with a TV camera and an image analyzer. In addition, the coke 4% flour was added.

As a result, the formation of the above-mentioned fine calcium fluoride requires a melt of high CaO ₂ Si 0 _2. For this reason, it is necessary to lower the Si ₂ % in the iron ore or to reduce the content of the iron ore. quartz (Si0 ₂₎ and clay - the Si0 ₂ minutes (Si0 _₂ A1 ₂ 0 ₃₎ may not allowed readily soluble in the melt that was bought amount is important. Further, this dissolution ease Si0 ₂ is result of various investigation including ore from 0.5 to 7.6%, it was confirmed that organize in is the component A1 ₂ 0 ₃ and Si 0 ₂ ratio in the ore.

Figure 1 shows the relationship between the content of ₂ % Si0 in iron ore and the amount of fine calcium ferrite and slag with a width of 10 m or less. The amount of calcium ferrite slag can be considered to correspond to the amount of melt actually existing. This result, Si0 ₂ in the iron ore is 1.5% or less was guided good generation of fine Karushiyuu Muferai bets. Figure 2, for Si0 ₂ is from 0.5 to 7.6% of the normal import ore in the iron ore, A1 ₂ 0 ₃ Z Si0 ₂ weight ratio less the width 10〃 m of fine local Shiyu um Blow wells and scan in the iron ore It shows the relationship of the amount of lag. Si0 ₂ from becoming 1.5% or less of the ore almost equivalent fine local shoe © beam Blow wells amount and slag weight. Al _₂ 0 ₃ ZSi0 ₂ is that of 0.3 or less, or, Al ₂ 0 of Ru value the ore containing the ₃ ZSi0 _₂ Si0 ₂ can be substituted with more than 1.5% of the ore.

Based on the above findings, CaOZSi0 ₂ (basicity) of sintered ore and Pisorai preparative iron ore was adjusted to the normal range 1.6 to 2.2 are, Si0 ₂ 1.5% or lower Si0 ₂ iron ore A sintering test was carried out using a mixed brand of raw materials. In addition, 4% of coke powder was added as a solid fuel to the blended raw materials.

As a result of the test, a special mineral structure different from the conventional one was obtained when the ratio of pisolite iron ore in the obtained sintered ore was 40 to 70%. Figures 3 to 5 show the organization. In addition, pisolite in conventional sinter Fig. 6 shows the mineral structure of the iron ore part for comparison.

Coarse-grained pisolite iron ore of about 2 ii or more: ① Unmelted pisolite iron ore is densified as shown in Fig. 3 (a), and its surroundings are 10 as shown in Fig. 3 (b). Is it surrounded by fine calcium ferrite of less than 〃 m, or ② As shown in Fig. 4 (a), there is a trace of the original shape of the piezolite iron ore, but it is assimilated as a whole by melting. The matite particles and calcium ferrite that binds the particles were precipitated in a granular form (FIG. 4 (b) :). Note that some of the sintered ore particles were mixed in texture and structure. Fine-grained pisolite iron ore powder or intermediate particles adhering to other raw materials of about 0.5 mm or less include ③ granular hematite particles and iron oxide particles as shown in Fig. 5. (It grows up to 20-30 m in width, though it is part of the pole), and is very similar in structure to the coarse-grained pisolite iron ore in Fig. 4. Was. That is, the calcium sulfate connective tissue is a special feature.

In the production of sintered ore for iron making, the pores are not closed without completely melting all the raw materials in order to maintain the permeability of the sintering bed, that is, to ensure coke combustion. Therefore, some raw materials remain unmelted. In Figure 5, the unmelted ore was removed and photographed. Since iron-containing raw materials are blended with coke powder and MgO-containing raw materials such as serpentine, which have a relatively wide particle size distribution, calcium ferrite is theoretically formed around these coarse particles. do not do. Therefore, 20 samples of about 20 marauders were randomly selected from one sintering experiment, and the ratio of each structure in the solid part Να 1 to 6 excluding unmelted raw material other than pisolite iron ore in each particle cross section was calculated. Averaged. The results are shown in Table 1. Table 1 Pisorai door iron ore and low-Si0 ₂ (≤ 1.5%) iron ore

Blending sintered experimental results (CaOZSi0 ₂ = 1.6)

Pisolite

Να & ¾ ： ^ f- 7 H '5 ^ HS. TO iz ¾fi ¾¾¾ ^!

1 on Q 1 n Q

0 7V 丄 U 10% 7% 19%

2 AC) 1 丄 fi ϋ 4 2 12

3 50 16 19 46 5 3 11

4 60 18 20 45 4 2 11

5 70 19 22 41 5 3 10

6 80 17 12 33 6 9 23 Remarks; Microstructure ①: Densified pisolite iron ore particles surrounded by fine particles with a width of 10 m or less

Microstructure ②: There are traces of pisolite iron ore particles but they are assimilated to granular particles and calcium ferrite.

Tissue ③… Granular hematite particles and calcium silicate ④Tissue ④… Granular hematite particles and glassy silicate Tissue ②… Magnetic particles, calcium carbonate and glassy silicate

Microstructure: Reoxidized hematite particles, magnetite particles, calcium ferrite and vitreous silicate As can be seen from Table 1, the ratio of Not 2 to 5 pisolite iron ore is 40%-70% It can be seen that the area ratio of organizations ①, ② and ③ is large in the range of 、, and the total exceeds 80%. The reason why the structure 1 and the structure ₂ increase at a low α1 ratio of 30% pisolite iron ore is because the added Si02-based auxiliary material increases and is easily assimilated. In addition, it is considered that the reason why the texture increases when the ratio of the iron ore of Noi 6 is as high as 80% is that the gas permeability of the bead is impaired and the combustion becomes uneven.

In the conventional sintered ore, as shown in Fig. 6 (a), unmelted residual In iron ore, large cracks are generated concentrically or from the surface to the center, and a number of irregular pores surround it, and the thickness of the wall between the pores becomes extremely thin, resulting in an extremely brittle structure . In addition, the porous part surrounding the residual pisolite iron ore is made up of granular matite particles combined with vitreous silicate as shown in Fig. 6 (b). And it has the characteristic of poor reducibility. The binder phase in Figs. 3 to 5 is calcium ferrite, which is known to be excellent in low temperature reduction powdering resistance and reducibility. In fact, the low-temperature reducible powder index (RDI) was significantly improved to 34 ± 2 in the present invention, compared to 37 ± 3 in the conventional method. Furthermore, looking at the pore structure in Figs. 3 to 5, it is not amorphous but round, and the thickness of the wall between the pores is also increased, resulting in high strength. This change in the pore structure is closely related to the fluidity of the melt, and the calcium ferrite-based melt has a high fluidity, and thus has an unambiguous relationship with the formation of the calcium ferrite bonded phase.

Pisorai DOO iron ore and Si0 _2: raw material consisting of 1.5% or less of iron ore results in baked Yuinabe test are shown in Figure 7. It is clear that the sinter ore yield and cold strength (JIS drop strength) are significantly improved when the ratio of pisolite iron ore, which is characterized by the above calcium sulfate composite phase, is 40-70%. It is. The low Si0 ₂ iron ore Runowa be lowered yield large active in more than 70% formulation is was melt itself as a binder phase decreases because Si0 ₂ is small.

Then it was sintered test by replacing the low Si0 ₂ iron ore in the formulation to Al _₂ 0 ₃ ZSi0 ₂ or less 0.3% low A1 ₂ 0 ₃ ore. Since the tendency did not change when the basicity of the sinter was 1.6 to 2.2, the results for cases 1 and 6 are shown in Fig. 8. Low A1 ₂ 0 ₃ yield if be replaced with ore Osaere the substitution rate of 60% or less, that the cold strength can be maintained is clear. Also, this replacement At a rate of 60% or less, the structure of the sintered ore is essentially the same as in Figs. 3 to 5, and the proportion of fine calcium ferrite of several m / m or less has increased.

In actual sintering operations, strikes at Yamamoto may cause shortages.

Therefore, the above "Pisorai bets iron ore and low Si0 ₂ iron ore mixed material" and the degree of throat "Pisorai preparative iron ore, low Si0 Blend raw material ₂ iron ore and low A 1 ₂ 0 ₃ ore" is "Al ₂ 0 ₃ ZSi0 or ₂ can be substituted with greater than 0.3 iron ore ", as a result of the sintering tests is Figure 9. Since there was no significant difference in the results (trends) depending on the basicity, a basicity of 1.9 is shown. Also in this test, the amount of coke powder added was 4%. From Fig. 9, it was found that up to the substitution rate of 20%, the yield slightly decreased and the cold strength could be maintained.

That is, as iron-containing materials other than return ores, to 80% or more the total amount of high-grade iron ore and Al _₂ 0 ₃ / Si0 ₂ mass ratio of 0.3 or less of iron ore below the 1.5% or Si0 ₂ content The above structures (1), (2), and (3) could be obtained even if they were blended in such a manner.

〔Example〕

Hereinafter, the effects of the present invention will be described with reference to examples. The mineral texture is a mixture of Figs. 3 to 5, and it has been confirmed that the total is 80% or more.

Example 1

Table 2 shows typical blended raw materials (mainly hematite ore) and their sintering operation results in actual equipment. Condition A in Table 3 is the sintering of only the iron oxide ore, and Condition B is the case where the proportion of the iron ore in the new raw material of the blended raw material in Table 2 is 30%. Conditions C and D are It is an example of the sintering operation result by the light method. The yield, production rate and cold strength of single grade of pisolite iron ore are remarkably reduced, and the yield is considerably lower than that of Table 2 when the percentage of pisolite in the new raw material is 30%. On the other hand. Si0 ₂ is as indicated by the condition C and D is blended under conditions of the present invention 1.5% or lower Si 0 ₂ iron ore, the current average yield shown in Table 2, production rate, and cold strength Equivalent characteristics were obtained.

^ «S combination ^ and ^^^ result in Table 2

* {%) Table 3 Pisolite stone quantity

* Fiber and cox

Chemical organization

material

T.Fe CaO Si0 _₂ A1 ₂ 0 ₃ High Rollo stone -F 67,1% 0.1% 1.5% 0.8 % Awakening: _₂ 0 ₃ / Si0 ₂ ore - G 65.3 0.0 3.1 0.9 Example 2

Table 4, the present invention a portion of the low Si0 ₂ ore Pisorai preparative iron ore and Si0 ₂ is comprised et or 1.5% or lower Si0 ₂ iron ore raw materials Al _₂ 0 ₃ ZSi0 ₂ is 0.3 or less iron ore This is the result when the sintering is performed in the range of the above condition. In this case as well, the results as in Table 2 were obtained.

Table 4 Example of operation results by the present invention method Raw material condition E condition F condition G ore A 70.0% 50.0% 40.0% Other than returned ore

Iron ore B 12.0 12.5 0 Iron content

Iron ore F 0 12.5 24.0

Iron ore D 0 12.5 36.0 Mixing ratio

Iron ore G 18.0 12.5 0 New Iron-containing raw material 84.6 82.3 82.7

Limestone 13.3 15.3 14.8

Serpentine 2.1 2.4 2.5

Returned ore 19.2 18.1 19.2 fee

Coke 3.9 3.9 3.8 Yield (%) 82.2 83.0 82.3 Production rate (t Zd / m ² ) 32.3 33.9 32.5

JIS-SI (%) 89.0 88.3 89.2 Composition

JIS-RI (%) 67.0 66.3 66.5

RDI (%) 35.1 35.5 36.0

* Returning and coking are the ratio of outsourcing to new raw materials. ()

Table 5 shows the result when a portion of the iron ore raw material mixture in Table 4 Al _₂ 0 ₃ ZSi0 ₂ is sintered and replaced by larger iron ore than 0.3. In this case Yield and production rates were slightly lower than those of the normal raw materials in Table 2, but were much higher than those in Conditions A and B in Table 3, and the cold strength was almost the same as in Table 2.

Table 5 Example of sintering operation results by the method of the present invention

* Returning and coking are the ratio of outsourcing to new raw materials (%)

[Industrial applicability]

As described above, according to the present invention, the yield of sinter ore, It is possible to obtain the same results as before by using a large amount of pisolite iron ore, which has been regarded as a problem in order to lower the cost. The depletion of conventional high quality hematite ore is clear. The method of the present invention, which makes it possible to use abundant and inexpensive pisolite iron ore in a large amount, can solve the resource problem and greatly contribute to reducing the cost of iron.

Claims

The scope of the claims

1. In the cross section of the sinter, more than 80% by mass of the solid portion excluding the unmelted residue of the sintering raw material other than the iron oxide iron ore surrounded the dense iron iron ore with calcium ferrite. Or a mixture of granular hematite particles having traces of iron ore iron ore and calcium ferrite that binds the hematite particles, or a mixture thereof. Sinter for iron making. '

2. The sintered ore for steelmaking according to claim 1, wherein the sintered ore structure is mixed with a structure composed of granular hematite particles and a calcium sulfate.

3. In a method for producing a sintered ore for iron making, in which iron-containing raw materials such as iron ore and auxiliary raw materials, carbonaceous material, and moisture are sintered by a sintering machine, iron-containing raw materials other than returned ore are stone and, Si0 ₂ is with 1.5 mass% of high-grade iron ore weight content, and Pisorai preparative method for producing iron for sinter iron ore and Toku徵that blending 40 to 70 wt%.

4. As the iron-containing materials other than return ores, superseded by iron ore and 60 mass% or less Al _₂ 0 ₃ / Si0 ₂ mass ratio of 0.3 or less of a high-grade iron ore 1.5 mass% or less Si0 ₂ content 4. The method for producing a sintered ore for iron making according to claim 3, wherein the method is performed.

5. As the iron-containing materials other than return ores, Pisorai preparative iron ore, Si0 ₂ content of the mass ratio of high-grade iron ore and A OsZSiOs 1.5 mass or less

5. The method for producing a sintered ore for iron making according to claim 4, wherein the iron ore having a total content of 0.3 or less is blended so as to be 80% by mass or more.