WO2006030968A1

WO2006030968A1 - Method for producing sintered steel

Info

Publication number: WO2006030968A1
Application number: PCT/JP2005/017436
Authority: WO
Inventors: Hideaki Sato; Nobuyuki Oyama; Satoshi Machida; Kenji Oya
Original assignee: Jfe Steel Corporation
Priority date: 2004-09-17
Filing date: 2005-09-15
Publication date: 2006-03-23
Also published as: JP5004421B2; TW200617181A; KR20060101864A; JP2006111959A; TWI299362B; KR100787359B1

Abstract

Disclosed is a method for producing a sintered steel wherein a sintered steel is produced from a raw material for sintering which is composed of an iron ore A having a crystal water content of not less than 9.0 mass%, an iron ore B having a crystal water content less than 4.0 mass% and an iron ore C having a crystal water content of not less than 4.0 mass% and less than 9.0 mass% with a mixing ratio among the iron ore A, iron ore B and iron ore C being within the area defined by the points a, b, c, d and e in Fig. 1, preferably within the area defined by the points b, c, d, e, f and g in Fig. 2.

Description

Description Method for producing sintered ore Technical Field

The present invention relates to a method for producing sintered ore used as a main raw material for blast furnaces and the like. Background art

Sinter ore, the main raw material for blast furnaces, is generally manufactured as follows. First, raw material ore (fine iron ore) is blended with carbonaceous materials such as lime powder and other CaO-containing secondary materials, quartzite and serpentine and other Si 0 ₂ containing raw materials and coatus powder. Add the appropriate amount of water, mix and granulate. This granulated compounded raw material (sintered raw material) is filled to a predetermined thickness on the pallet of a Dwytroid-type sintering machine, and after igniting the carbonaceous material on the surface of this packed bed, air is directed downward. While sucking, the charcoal inside the filled bed is combusted, and the blended raw material is sintered by the combustion heat to form a sintered cake. The sintered cake is then sized to obtain a product sintered ore having a particle size of several mm or more.

High quality sintered ore is required for stable blast furnace operation. Generally, the quality of sintered ore is indicated by cold strength, reduced powder index (RDI), and reducibility (RI). It has a great influence on the stability of the state of falling in the furnace, air permeability and liquid permeability in the furnace, ore reduction efficiency, and high temperature properties. For this reason, strict quality control is performed in the manufacturing process of sintered ore. In addition, in order to reduce the production cost of sintered ore, it is required to improve the yield of sintered ore products, and to improve the efficiency and productivity of the sintered ore production line.

Since Japan does not have iron ore resources in the country, iron ore, which is a raw material for sintered ore, relies on 100% imports from overseas. In recent years, iron ore imports accounted for about 60% of Australian ore, about 20 to 25% of South American ore, and about 10 to 15% of Indian ore.

As shown in Table 1, iron ores are roughly classified into hematite ore, magnetite ore, limonite ore, and maramampa ore. Among these, Fig. 7 shows enlarged structure photographs of hematite ore, limonite ore, and maramamba ore. Fe oxide main weight average crystal water content -0.25mm

Species Production area

Oval Form (mm) vmass%) (mass%) Hematite Ore Fe ₂ 0 ₃ Golds Siege Australia 2.8 1.8 22 Eight Masley Australia 2.5 3.7 28 Newman ¾ State 3.0 2.5 22 Itabira South America 2.5 1.5 30 2.2 24 Donimarai India 3.3 1.8 16 Magnetite ore Fe ₃ 0 ₄ Melanore South America 2.8 1.8 18 Limonite ore Fe _z O ₃ 'nH ₂ 0 Lobliba Australia 3.1 9.9 10

(FeOOH) Yandee / UGID Australia 3.9 10.4 6 Yandee / LG1D Australia 3.1 12.1 20 Maramamba Ore Fe _z O ₃ + Fe00H Mac Australia 1.8 5.8 38

6

3 South American ores are mainly composed of hematite ore with low gangue content and high Fe grade, and some magnetite ore has been used as a high-quality raw material for sintered ore. However, there is a problem that transportation costs are high because the production area is far away.

Indian ore, although gangue content such as S i 0 ₂ is higher than that of South American ore, high-quality hematite ore and hematite ore containing about 4 to 5 mass% of crystal water are representative ores. It is one of the important iron ore resources. However, compared to South America and Australia, reserves are less, and mining and transportation to the port are delayed.In addition, infrastructure development for unloading is delayed, and shipments are restricted due to monsoons. , Etc., and the import ratio is struggling to grow.

— On the other hand, Australian ore is also the main source of iron ore supply, with production increasing significantly since the 1980s, thanks to aggressive investment by mining companies. However, high-quality hematite ore, which has been used favorably in the Japanese steel industry, has been heading toward the drought after 30 years of development, and has been developed since the mid-1990s. Limonite ore, which has been dredged, has reached its peak in production. On the other hand, new mines developed in recent years often produce ores mainly composed of maramanpa ore.

Here, the marampa ore is a generic name for iron ore produced from the maramanpa deposit in Australia. Generally, it is a goethite (F e ₂ 0 ₃ 'H ₂ 0) and marte (Fe ₂ with a magnetite structure). 0 ₃ ) as the main mineral and the water content of crystallization compared to hematite ore

(LO I. The same applies below) ore. LO I. Is according to JISM 8850. In terms of brand names, West Angelus or MAC ore is a typical iron ore. A typical example of limonite ore is pisolite ore. This pisolite ore generally has an internal structure in which the gap between fish egg-shaped hematite (Fe ₂ 0 ₃ ) is filled with goethite (Fe ₂ 0 ₃ 'H ₂ 0), and is even further than marampa ore. It is an ore with a high crystal water content. In terms of brand names, low ore and ordi kudina ore are typical iron ores. In the future, it is also expected to use a brand called LC ID, which has a higher crystal water content than the Jandi Kujina ore.

Conventionally used hematite ore has good sinterability, and a sintered ore whose raw material composition is adjusted to a basicity (C aOZS i 0 ₂ ) of 1.7 or more by adding a C a O source auxiliary material. Has good quality, productivity, and yield. T JP2005 / 017436

4 On the other hand, limonite ore among Australian ores usually has a crystallization water content of about 9 to 1 l mass%, and there are few fines and the particle size is coarse. As you can see, there are many coarse pores in the mineral structure. For this reason, when the limonite ore is fired, the crystal water in the ore escapes and becomes more porous, resulting in a crack. In addition, if a CaO-based melt enters the relatively coarse pores from which crystal water has escaped during the sintering process, it will rapidly assimilate and cause excessive melting. Therefore, when a large amount of limonite ore is blended, not only does the strength of the sintered ore decrease, but an excessive melt is generated in the sintering bed, resulting in a site that grows into a rock plate shape. There is significant unevenness in ventilation between the part and other parts, and an unfired part remains below the overmelted rock-like part, resulting in a significant drop in yield.

On the other hand, maramanpa ore, which was newly developed as an Australian ore and is expected to increase in use in the future, generally has a crystal water content of about 4 to 6 mass%, and it has fewer rough air holes than limonite ore. Since there is little crystallization water, excessive melting during firing is alleviated. However, because there are fine pores in the entire structure, it is easy to absorb the melt, and the absorbed melt assimilates the ore from the periphery, and when the Fe concentration in the melt increases, the viscosity increases rapidly, Firing is completed with pores left inside. For this reason, the melt does not spread sufficiently to the adjacent ore, and the marampa ore portion becomes a sintered ore with fine pores remaining, so the strength decreases and the yield also decreases. In addition, because Maramanpa ore has a fine particle size, when used in large quantities, the particle size after raw material granulation does not increase in the raw material processing step of sintering, and the bed of the bed charged on the sintering machine pallet does not increase. Air permeability will deteriorate and productivity will decrease.

As mentioned above, high-quality hematite ore and magnetite ore tend to wither, while limonite ore and maramamba ore are used in large quantities, the quality and productivity of the resulting sintered ore is reduced. There is a big problem. For this reason, high-quality sintered ore (for example, rotational strength according to JISM 8 7 12: 66% or more) must be manufactured at a high production rate (for example, 1.5 t Z h Zm ² or more) at low cost. Is currently becoming difficult. 5 Disclosure of the invention

The present invention provides a method for producing a sintered ore that can produce a high-quality sintered ore at a low cost with a high production rate and yield under the circumstances of supplying raw iron ore as described above. With the goal.

The inventors of the present invention have studied the optimum blending conditions for solving the above-mentioned problems on the premise that the above-mentioned plural types of iron ores are blended simultaneously in the sintering raw material. As a result, hematite ore, magnetite ore, limonite ore and maramampa ore were mixed at a mixing ratio considering the influence and interaction of their properties on the sintering process, and the total raw ore It has been found that high-quality sintered ore can be produced at low cost with high productivity and yield by blending at a blending ratio such that the average crystallization water content and particle size are at predetermined levels.

The present invention has been made on the basis of the above findings, and the gist thereof is as follows.

[1] The raw ores to be blended are iron ore A having a crystallization water content of 9.0 mass% or more, iron ore B having a crystallization water content of less than 4. O mass%, and a crystallization water content of 4 A sintering raw material composed of iron ore C with O mass% or more and less than 9.0 mass%,

The blending ratio of iron ore A, iron ore B and iron ore C is shown in Fig. 1. Point a (iron ore A: 4 O mass%, iron ore B: 5 O mass%, iron ore C: 1 O mass%), point (iron ore A: 7 mass%, iron ore B: 5 O mass% :, iron ore C: 43 mass%), point c (iron ore A: 1 2 mass%, iron ore B: 1 8 mass% :, iron ore C: 7 O mass%), point d (iron ore A: 23 mass%, iron ore B: 7 mass%:, iron ore C: 7 O mass%) e (Ore A: 4 O mass%, Iron Ore B: 36 mass%:, Iron Ore C: 24 mass%) A method for producing sintered ore.

[2] In the production method of [1] above, the mixing ratio of iron ore A, iron ore B, and iron ore C is shown in Fig. 2. Point b (iron ore A: 7 mass%, iron ore B: 5 O mass%:, iron ore C: 43 mass%), point c (iron ore A: 12 mass%, iron ore B: 18 mass% :, iron ore C: 70 mass%), point d ( Iron Ore A: 23 mass%, Iron Ore B: 7 mass% :, Iron Ore C: 70 mass%), Point e (Iron Ore A: 4 O mass%, Iron Ore B: 3 6 mass% :, Iron ore C: 2 4 mass%), point ί (iron ore A: 4 Omass%, iron ore B: 4 Omass%, iron ore C: 20 mass%) and point g (iron ore A: 3 Omass%, iron ore B: 5 A method for producing a sintered ore characterized by producing sintered ore from a sintering raw material within a range surrounded by Omass%, iron ore C: 2 Omass%). ] In the production method of [1] above, the mixing ratio of iron ore A, iron ore B, and iron ore C is shown in Fig. 3, point a (iron ore A: 4 Omass%, iron ore B: 50mass%, iron ore. Stone C: 10 mass%), Point b (Iron Ore A: 7 mass%, Iron Ore B: 50 mass%:, Iron Ore C: 43 mass%), Point h (Iron Ore A: 1 1. 5 mass% , Iron ore B: 2 Omass% :, iron ore C: 68. 5 mass%), point i (iron ore A: 3 Omass%, iron ore B: 2 Omass% :, iron ore C: 5 Omass%) and It is characterized by producing sintered ore from a sintering raw material within the range surrounded by point e (iron ore A: 4 Omass%, iron ore B: 36 mass% :, iron ore C: 24 mass%) A method for producing sintered ore.

[4] In the production method of [2] above, the blending ratio of iron ore A, iron ore B and iron ore C is

Point b (Iron Ore A: 7 mass%, Iron Ore B: o Omass% :, Iron Ore C: 43 mass%), Point h (Iron Ore A: 1 1 mass%, Iron Ore ^] Έ>: 2 Omass%:, iron ore C 69 mass% ;, point i (iron ore A: 3 Omass%, iron ore Β: 20 mass%: iron ore c 50 mass%), point e (iron ore A: 4 Omass% , Iron ore D: 36 mass%:, iron ore 24 mass%), point ί (iron ore A: 4 Omass%, iron ore Β: 4 Omass%,

20 mass%) and g (iron ore A: 3 Omass%, iron ore B: 5 Omass%, iron ore C: 2 Omass%). A method for producing a sintered ore, characterized in that is produced.

[5] The method for producing sintered ore according to [1] or [2] above, wherein the amount of raw ore in the sintered raw material is 60 mass% or more. According to the present invention, high-quality sintered ore can be produced at a high production rate by blending three ores of iron ores A, B, and C as raw ores at a specific limited blending ratio in the sintered raw material. It can be manufactured at a low cost with yield. Brief Description of Drawings

Fig. 1 is a drawing showing the range of iron ore A, B, and C content specified by Tomoaki. FIG. 2 is a drawing showing a more limited range of the mixing ratio of iron ores A, B, and C specified by the present invention.

FIG. 3 is a drawing showing a more preferable range of the mixing ratio of iron ores A, B, and C when the mixing range of FIG. 1 is used as a pace.

FIG. 4 is a drawing showing a more preferable range of the mixing ratio of iron ores A, B, and C when the mixing range of FIG. 1 is used as a base.

FIG. 5 is a drawing showing a more preferable range of the mixing ratio of iron ores A, B and C when the mixing range of FIG. 2 is used as a base.

FIG. 6 is a drawing showing a more preferable range of the mixing ratio of iron ores A, B, and C when the mixing range of FIG. 2 is used as a base.

Figure 7 shows micrographs of the microstructures of hematite ore, limonite ore and maramampa ore.

Fig. 8 is a graph showing the relationship between the amount of quicklime added to the sintered raw material and the production rate of the sintered ore. FIG. 9 is a graph showing the relationship between the ratio of fine ore having a particle size of 0.25 mm or less in the raw ore mixed with the sintered raw material and the production rate of the sintered ore.

FIG. 10 is a drawing showing the mixing ratio of iron ores A, B, and C in each example.

BEST MODE FOR CARRYING OUT THE INVENTION

In order to produce high-quality sintered ore at a high production rate, the crystal water content (LO I. The same shall apply hereinafter) and grain size of the raw ore to be mixed with the sintering raw material are important factors. Matite ore, magnetite ore and maramamba ore can be distinguished by the content of crystal water as follows.

(1) Iron ore A-limonite ore with a crystal water content of 9. Omass% or more

(2) Iron ore with crystal water content less than 4. Omass% B-Hematite ore 'Magnetite ore

(3) Iron ore with crystal water content of 4. Omass% or more and less than Omass% C = Maramanpa ore

The normal particle sizes of these iron ores are the weight average diameter of limonite ore of 3. Omm or more, hematite or magnetite ore of 2.2 mm or more, and marampapa ore of 1.9 mm or less.

In this sinter ore manufacturing method, the raw ore in the sintering raw material is composed of the above three types of iron ores A, B, and C. Iron Ore A: 4 Omass%, Iron Ore B: 5 Omass%, Iron Ore C: 1 Omass%), Point b (Iron Ore A: 7 mass%, Iron Ore B: 50 mass% :, Iron Ore C: 43 mass% ), Point c (iron ore A: 12 mass%, iron ore B: 18 mass% :, iron ore C: 7 Omass%), point d (iron ore A: 23 mass%, iron ore B: 7 mass%: , Iron ore C: 70 mass%) and point e (iron ore A: 40 mass%, iron ore B: 36 mass% :, iron ore C: 24 mass%). As iron ore B, hematite ore or Z and magnetite ore are used. In the present invention, the raw material ore refers to iron ore as a new raw material, and so-called return ore is not included in the definition of raw material ore.

Here, the limit line i in Fig. 1 defines the amount of iron ore B (hematite ore 'magnetite ore) combined, and the iron ore exceeds the limit line i (5 Omass% of all raw ores). Compounding B increases the production cost of the sintered ore, which is contrary to the object of the present invention. In other words, increasing the blending ratio of expensive iron ore B, which is high in quality compared to other ores, and that tends to wither, itself increases the manufacturing cost and supplies iron ore from the current production area. To increase the usage rate of iron ore B beyond the limit line 6

9 There is no choice but to increase South American ore (the most expensive iron ore B by production area) that has surplus production capacity.

The limit line opening in Fig. 1 regulates the mixing limit of iron ore A (limonite ore). When iron ore A is mixed beyond the limit line opening (4 O mass% of all raw ores), iron ore A large amount of rock-like melt is generated by A, and the air permeability of the sintered bed is greatly hindered. As a result, the quality and productivity of the sintered ore are reduced. In order to prevent iron ore A from creating a rock-like melt that impedes aeration in the sintered bed, iron ore A must be distributed and charged on the sintered bed. It is. For this purpose, it is necessary to coordinate pseudo particles mainly composed of iron ore (iron ore B and Z or iron ore C) around the pseudo particles mainly composed of iron ore A in the raw material packed bed. In order for the pseudo-particles mainly composed of stone A to be appropriately surrounded by other pseudo-particles mainly composed of iron ore, etc. Is considered to be 1.5 or more. If the ratio of iron ore A is 4 O mass% or less, the ratio of the pseudo particles is satisfied. In addition, it is more preferable that the number of pseudo-particles mainly composed of iron ore is about 3 to 4 while the number of pseudo-particles mainly composed of iron ore A is 1. The ratio of the raw material ore in the sintering raw material is preferably about 60 to 8 O mass%. Therefore, if the ratio of iron ore A is 4 O mass% or less, the ratio of iron ore A in the sintering raw material is about 24 to 3 2 mass% or less, and the above-mentioned pseudo particle ratio is satisfied. Will be.

The limit line C in Fig. 1 defines the mixing limit of iron ore C (maramanpa ore) with a large amount of fine ore, and the iron ore C exceeds the limit line c (7 O mass% of all raw ores). When mixed, problems due to the grain size of iron ore C become obvious. In normal sintering operations, fine ore with a particle size of 0.25 mm or less is known to impair the permeability of the sintered bed, and such a fine powder with a particle size of 0.25 mm or less is known. In order to remove the adverse effects of the ore, granulation of the sintering raw material using quick lime or slaked lime in the binder allows the raw material particles charged in the sintering machine to have a weight average diameter of 3 to 3 It is set to 6 mm. Generally, in the granulation of sintered raw materials, the amount of pine binder added is adjusted according to the content of fine ore with a particle size of 0 · 25 mm or less in the raw ore. The effect of is proportional to the amount of addition in the region where the amount of addition is small, but when the amount of addition increases beyond a certain level (about 2.5 mass% or more), the effect becomes saturated. Therefore, the proportion of iron ore C with a large amount of fine ore PT / JP2005 / 017436

10 also has a limit, and as described below, the limit is about 7 O mass% specified by the limit line C.

In general, the proportion of fine ores with a particle size of 0.25 mm or less is about 4 O mass% for iron ore C, about 5 to 12 mass% for iron ore A, and about 20 to 3 for iron ore B. Although it is about 0 mass%, as shown in Fig. 9, if the proportion of fine-grained ore with a particle size of 0.25 mm or less in the raw ore exceeds about 35 mass%, it will adversely affect the sintering and produce The rate starts to drop. If the proportion of iron ore C is 70 mass% or less, the proportion of fine-grained ores with a particle size of 0.25 mm or less is about 25 to 30 mass% or less, and the effect on productivity is small.

The limit line 2 in Fig. 1 defines the limit (upper limit) of the average crystal water content of the raw ore (iron ore A + B + C). When the crystallization water content of the raw ore is high, the crystallization water is eliminated and a sintered structure with many pores is formed. Under the condition of a constant firing rate, the strength and yield of the sinter are reduced. On the other hand, if the firing rate is reduced to secure the firing time, the productivity is lowered. In addition, if the amount of carbon is increased to increase the amount of heat, excessive melting occurs, resulting in deterioration or non-uniform air permeability and a decrease in yield. It was found that the average crystal water content of the raw ore (iron ore A + B + C) needs to be adjusted to 6. O mass% or less for such problems. Based on each crystal water content of iron ores A, B and C, the mixing ratio of iron ores A, B and C should be defined by two limit lines, that is, iron ore A should not exceed two limit lines. If blended and iron ores B and C are blended so as not to fall below the limit line 2, the average crystallization water content of the entire raw ore (iron ore A + B + C) should be adjusted to 6.0 mass% or less. Can do.

The limit line E in Fig. 1 defines the limit (lower limit) of the average grain size of the raw ore (iron ore A + B + C). If the particle size of the raw ore is too small, the air permeability in the sintered bed will deteriorate and the yield of the sintered ore will decrease. It was found that the average particle size of the raw ore (iron ore A + B + C) needs to be adjusted to 2.2 mm or more for such problems. Based on the average particle size of iron ores A, B, and C, the blending ratio of iron ores A, B, and C should be specified by the limit line E. In other words, iron ore A should be blended so as not to fall below the limit line E If the iron ores B and C are blended so as not to exceed the limit line E, the average particle diameter of the entire raw ore (iron ore A + B + C) can be made 2.2 mm or more.

From the above results, in the present invention, the mixing ratio of iron ores A, B, and C in the raw ore is shown in FIG. It is defined as the range demarcated by the limit line -1, 1, 1, 1, i.

Furthermore, in a more preferable production method of the present invention, the blending ratio of the iron ores A, B, and C in the raw ore is shown in FIG. 2 as point b (iron ore A: 7 mass%, iron ore B: 50 mass%). :, Iron ore C: 43 mass%), point c (iron ore A: 1 2 mass%, iron meteorite B: 1 8 mass% :, iron ore C: 7 Omass%), point d (iron ore A: 23 mass%) , Iron ore B: 7 mass% :, iron. Ore C: 70 mass%), point e (iron ore A: 4 Omass%, iron ore B: 36 mass% :, iron ore C: 24 mass%), point (iron ore Stone A: 4 Omass%, Iron Ore B: 4 Omass%, Iron Ore C: 2 Omass%) and g (Iron Ore A: 3 Omass%, Iron Ore B: 5 Omass%, Iron Ore C: 2 Omass%).

Here, the reason why the limit line i, mouth, c, n, and e in Fig. 2 are specified is as described above. Furthermore, the limit line defines the lower limit of the amount of iron ore C (maramanpa ore), so by adding iron ore C so that it does not fall below this limit line, the amount of fine ore is cheap but low. Therefore, it is possible to produce high-quality sintered ore at a lower cost and at a higher production rate while actively blending iron ore C (maramanpa ore), which is likely to cause the above-mentioned problems.

Therefore, in the present invention, the mixing ratio of iron ores A, B, and C in the raw ore is within the range partitioned by one mouth and one by one haho into the limit line i in FIG. 2, that is, the points b and c described above. , Point d, point e, point ί and point g are preferable.

Among the ratios of iron ores A, B, and C shown in Fig. 1 and Fig. 2, more preferable are the proportions within the range further limited by the limit line as shown in Fig. 3 and Fig. 5. . In other words, when based on the blending range of Fig. 1, point a (Iron Ore A: 4 Omass%, Iron Ore B: 5 Omass%, Iron Ore C: 1 Omass%), shown in Fig. 3, Point b (Iron Ore A: 7mass%, Iron Ore B: 50 mass% :, Iron Ore C: 43mass%), Point h (Iron Ore A: 1 1. 5mass%, Iron Ore B: 2 Omass%:, Iron Ore Stone C: 68. 5mass%), point i (Iron Ore A: 3 Omass%, Iron Ore B: 2 Omass% :, Iron Ore C: 5 Omass%) and Point e (Iron Ore A: 4 Omass% , Iron Ore B: 36 mass%:, Iron Ore C: 2 mass%). In addition, when based on the blending range of Fig. 2, point b (iron ore A: 7 mass%, iron ore B: 5 Omass%:, iron ore C: 43 mass%), point h (shown in Fig. 5) Iron Ore A: 1 lmass%, 17436

12 Iron Ore B: 2 Omass% :, Iron Ore C: 69 mass%), Point i (Iron Ore A: 3 Omass%, Iron Ore B: 20 mass% :, Iron Ore C: 5 Omass%), Point e (Iron Ore Stone A: 4 Omass%, Iron Ore B: 36 mass% :, Iron Ore C: 24mass%), 点 (Iron Ore Α: 4 Omass%, Iron Ore B: 4 Omass%, Iron Ore C: 2 Omass% ) And g point (iron ore A: 3 Omass%, iron ore B: 5 Omass%, iron ore C: 2 Omass%).

The limit lines in Fig. 3 and Fig. 5 define more preferable blending conditions from the viewpoint of the strength of the sintered ore. The range surrounded by the point h, point c, point d, and point i, which deviates from the preferred range defined by the limit line, has been conventionally used as a sintering raw material. The ratio of iron ore B, which produces a dense sintered structure with little or less, is less than 20 mass%. On the other hand, the composition of iron ores A and C, in which the sintered structure tends to become porous due to the release of crystal water by firing, Since the ratio will exceed 8 Omass%, it is difficult to maintain the strength of the sinter (and thus maintain the production rate and yield). Therefore, when the mixing range shown in Fig. 1 is used as a base, the mixing ratio of iron ores A, B, and C is within the range defined by the limit line i.e. It is preferable to be within the range surrounded by point a, point b, point h, point i and point e. Also, when based on the blending range of Fig. 2, iron ore A, B, C The blending ratio of Fig. 5 is within the range defined by the limit line E ^^ Lone-Toho in Fig. 5, that is, within the range surrounded by point b, point h, point e, point ί and point g described above. It is preferable that

Further, among the mixing ratios of iron ores A, B, and C shown in FIGS. 1 and 2, the mixing ratio within the range further limited by the limit line h is preferable as shown in FIGS. 4 and 6. It is. In other words, if based on the blending range of Fig. 1, point a (iron ore A: 4 Omass%, iron ore B: 50 mass%, iron ore C: 1 Omass%), point b ( Iron Ore A: 7 mass%, Iron Ore B: 50 mass% :, Iron Ore C: 43 mass%), Point j (Iron Ore A: 8 mass%, Iron Ore B: 42 mass% :, Iron Ore C: 5 Omass %), Point i (iron ore A: 30 mass%, iron ore B: 20 mass% :, iron ore C: 5 Omass%) and point e (iron ore A: 4 Omass%, iron ore B: 36 mass) % :, iron ore C: 24 mass%). In addition, when based on the blending range in Fig. 2, point b (iron ore A: 7 mass%, iron ore B: 5 Omass% :, iron ore C: 43 mass%), point j ( Iron Ore A: 9 mass%, Iron Ore B: 41 mass% :, Iron Ore C: 5 Omass%), Point i (Iron Ore A: 3 17436

13

O mass%, iron ore B: 20 mass%:, iron ore C: 50 mass%), point e (iron ore A: 4 O mass%, iron ore B: 3 6 mass%:, iron ore C: 2 4 naass%), point f (iron ore A: 4 O mass%, iron ore B: 4 O mass%, iron ore C: 20 mass%) and point g (iron ore A: 30 mass%, iron ore) Stone B: 5 O mass%, Iron Ore C: 2 O mass%).

The limit line h in Fig. 4 and Fig. 6 defines more preferable blending conditions from the viewpoint of ore granulation. The range surrounded by point j, point c, point d and point i, which deviates from the preferred range defined by this limit line, is the particle size of 0.25 derived from iron ore C (maramanpa ore). In order to alleviate the influence of the sintered packed bed with fine ore of less than mm, the effect of the addition of quicklime starts to saturate (see Fig. 8). The blending range must be 2.5 mass% or more . Therefore, in this blending range, the effect of granulation of fine ore due to the addition of quicklime tends to be unstable, and the production rate and strength of sintered ore tends to decrease. Therefore, when the mixing range shown in Fig. 1 is used as a base, the mixing ratio of iron ores A, B, and C is within the range defined by the limit line in Fig. 4, i.e. The point a, the point b, the point: ϊ, the point i and the point e and the range enclosed by the point e are preferable. In addition, when the blending range in FIG. 2 is used as a base, the blending ratio of iron ore A, B, and C is within the range defined by the limit line E ^^ It is preferable to be within the range surrounded by point b, point j, point point e, point f and point g. -In the method for producing sintered ore according to the present invention, in order to sufficiently secure the effect of the regulation of the mixing ratio of iron ores A, B, and C described above, the amount of raw ore in the sintered raw material (iron ore) A + B + C) is preferably 6 O mass% or more. The amount of raw material ore is in the general range in the current sintering operation. However, if the raw material ore (iron ore A + B + C) content is less than 60 ma _S s%, it depends on other raw materials. Since the influence on the sinterability becomes obvious, the effect of the present invention is difficult to obtain.

In this paper, the raw ores to be blended in the sintering raw material are three types of iron ores A, B, and C. The raw material ores are mixed with auxiliary ingredients for component adjustment (for example, C a O-containing auxiliary raw materials, S i 0 ₂ Contained auxiliary materials, etc.), granulation aids (for example, quicklime), recovered powder in steel mills (mainly iron sources such as dust), carbonaceous materials (coatus powder, anthracite, etc.), sintered ore sieve powder Etc. are mixed to form a sintering raw material, and an appropriate amount of water is added to the sintering raw material and mixed and granulated. 05017436

Note that the general blending ratio of the new raw material and powder coatas contained in the sintered raw material is as shown below, assuming that the new raw material + coke == 100 mass%.

Raw material ore 60-80 mass%,

6-9 mass% limestone,

Quicklime 2.5 mass% or less

Serpentine 0.8-8-2.0 mass%

Sintered ore sieve powder 5 to 15 mass%,

5-10 mass% of recovered powder in steelworks,

(Dust, sludge, mill scale, dust collection, etc.)

Powder coatas: 2.5-5. 5mass%

There are various methods of mixing and granulation described above, and any method may be used. This granulated compounded raw material (sintered raw material) is filled on a pallet of a Dwytroid-type sintering machine to a specified thickness, and after igniting the charcoal on the surface layer of this packed bed, air is directed downwards. The charcoal inside the filled bed is combusted while sucking the bow I, and the blended raw material is sintered by the combustion heat to form a sintered cake. Then, by sintering the sintered cake, the product sintered ore having a particle size of several mm or more can be obtained. Example

As raw materials for sintering (compounding raw materials), raw material ore (pulverized ore) is 70ma _SS %, sintered undersieve powder is 1 Omass%, in-house recovered material (mainly iron source) is 7-8niass%, auxiliary raw materials 12 to 13 mass% of grain pine was blended. As raw ores, two or more of iron ores A, B and C specified by the present invention were used. Mix this sintered raw material with a drum mixer for 3 minutes, adjust the humidity, and then put the pseudo particles obtained by granulating for 3 minutes into a 30 Omm diameter pan test device to a layer thickness of 40 Omm. After igniting at 1, it was fired at a constant negative pressure of 1 OKP a to produce sintered ore.

In this test, the selection of iron ores A, B, and C and the amount of blending were made so that the product sintered ore had S i 0 ₂ : 4. 8 ~ 5.0 mass% and basicity: 1. 8 5 In addition, the amount of quicklime was adjusted according to the blending amount of iron ore C. The quicklime used had an activity of 320 m 1 and a particle size of 1. Omm or less. Mixing ratio of iron ore A, B, C in raw material ore, quick lime content in sintered raw material, production rate of obtained product sintered ore, cold strength (rotational strength according to JISM 8 7 1 2 ), + 1 O mm yield is shown in Table 2. In addition, the ore blending ratio of each example was plotted in the graph of FIG.

2

* 1 Iron ore A: Limonite ore

Iron Ore B: Hematite Ore 'Magnetite Ore Iron Ore G: Mara Mamba Ore

As shown in Table 2, by producing sintered ore from sintered raw materials containing iron ores A, B, and C according to the conditions of the present invention, both strength and yield are good while maintaining high productivity. Sintered ore can be produced. In addition, by blending iron ores A, B, and C in a more limited blending range as shown in FIGS. 2 to 6, a more excellent effect is obtained.

In addition, Comparative Examples 15 to 17 have good quality and yield as sintered ore, and the production rate is also good, but the raw material cost is very high, and it is actually adopted for the supply and demand balance of raw materials. This is an example of a raw material formulation that is difficult to do.

Claims

The scope of the claims

1. The raw ore to be blended is iron ore A with a crystal water content of 9. Omass% or more, iron ore B with a crystal water content of less than 4.0 mass%, and a crystal water content of 4.0. A sintering raw material composed of iron ore C of mass% or more and less than 9.0 mass%,

The blending ratio of iron ore A, iron ore B and iron ore C is shown in Fig. 1. Point a (Iron ore A: 4 Omass%, Iron ore B: 5 Omass%, Iron ore C: 10 mass%) , Point b (Iron Ore A: 7 mass%, Iron Ore B: 5 Omass% :, Iron Ore C: 43 mass%), Point c (Iron Ore A: 1 2 mass%, Iron Ore B: 18 mass% :, Iron Ore C : 7 Omass%), point d (iron ore A: 2 3 mass%, iron ore B: 7 mass% :, iron ore C: 7 Omass%) and point e (iron ore A: 4 Omass%, iron ore) B: 36 mass% :, iron ore C: 24 mass%) A method for producing a sintered ore characterized by producing sintered ore from a sintering raw material within a range surrounded by the mass.

2. The composition ratio of iron ore A, iron ore B and iron ore C is shown in Fig. 2. Point b (iron ore A: 7mass%, iron ore B: 5 Omass%:, iron ore C: 43mass%) , Point c (iron ore A: 1 2 mass%, iron ore B: 18 mass%:, iron ore C: 7 Omass%), point d (iron ore A: 2 3 mass%, iron ore B: 7 mass% :, Iron ore C: 7 Omass%), point e (iron ore A: 40 mass%, iron ore B: 36 mass% :, iron ore C: 24 mass%), point f (iron ore A: 40 mass%, iron ore B: 40 mass%, iron ore C: 2 Omass%) and g (iron ore A: 3 Omass%, iron ore B: 5 Omass%, iron ore C: 2 Omass%) 2. The method for producing a sintered ore according to claim 1, wherein the sintered ore is produced from a sintered raw material.

3. The mixing ratio of iron ore A, iron ore B and iron ore C is shown in Figure 3, point _a (iron ore A: 4 Omass%, iron ore B: 5 Omass%, iron ore C: 1 Omass% ), Point b (iron ore A: 7 mass%, iron ore B: 50 mass% :, iron ore .: 43 mass%), point h (iron ore A: 11. 5 mass%, iron ore B: 20 mass%:, Iron ore C: 68. 5 mass%), point i (iron ore A: 3 Omass%, iron ore B: 20 mass%:, iron ore .: 50 mass%) and point e (iron ore A: 4 Omass% , Iron Ore B: 36 mass% :, Iron Ore C: 24 mass%) 2. The method for producing a sintered ore according to claim 1, wherein the sintered ore is produced from a sintering raw material within the range.

4. The composition ratio of iron ore A, iron ore B and iron ore C is as shown in Fig. 5. Point (Iron ore A:

7mass%, iron ore B: 5 Omass% :, iron ore C: 43 mass%) _Λ point h (iron ore Α: 1

1 mass%, iron ore B: 2 Omass%:, iron ore C: 69 mass%), point i (iron ore A: 3

Omass%, iron ore B: 2 Omass% :, iron C, 5 Omass%), point e (iron ore A: 4

Omass%, iron ore B: 36 mass%:, iron ore c: 24mass%), dot ί (iron ore A: 4

0 mass%, iron ore B: 4 Omass%, iron ore C: 2 Omass%) and g point (iron ore A:

The sintered ore according to claim 2, wherein the sintered ore is produced from a sintering raw material within a range surrounded by 3 Omass%, iron ore B: 5 Omass%, iron ore C: 2 Omass%). Production method of ore.

5. The method for producing a sintered ore according to claim 1, wherein the amount of raw ore in the sintered raw material is 6 Omass% or more.

6. The method for producing a sintered ore according to claims 1 to 4, wherein iron ore A is made of limonite ore, iron ore B is made of hematite ore and magnetite ore, and iron ore C is made of maramamba ore.