JP7260786B2 - Method for blending raw materials for sintering and method for producing sintered ore - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of blending sintering raw materials and a method of producing sintered ore using the sintering raw materials obtained by this blending method.

Pisolite iron ore is used as a raw material for sintered ore. Patent Document 1 describes that a low Al ₂ O ₃ -containing pisolitic iron ore having an Al ₂ O ₃ content of 1.5% by mass or less is used in an amount of 50% by mass or more in the pisolitic iron ore. Further, Patent Document 2 describes that a pisolite ore having an alumina content of 2.5 mass% or more and a pisolite ore having an alumina content of 1.5 mass% or less are used together as the pisolite ore.

JP-A-2001-279334 JP-A-10-121154

_{According to} US _{Pat .} On the other hand, Patent Documents 1 and 2 do not pay attention to the particle size of iron ore.

According to the inventors of the present application, by classifying a plurality of types of iron ore in a coordinate system relating to the Al ₂ O ₃ content and particle size of iron ore and blending iron ore belonging to a predetermined classification at a predetermined blending ratio, It was found that the production rate of sintered ore was improved, and the present invention was completed.

The present invention is a sintering raw material blending method characterized by blending a plurality of types of iron ore so as to satisfy the following formulas (1) and (2).
74≦(Wb+Wc) (1)
100×Wb/(Wb+Wc)≧50 (2)

Wb is the mass ratio of iron ore belonging to the first category to all iron ores contained in the raw material for sintering. Wc is the mass ratio of the iron ores belonging to the second category to all the iron ores contained in the raw material for sintering. Class 1 and Class 2 are based on the mass ratio of alumina content to total iron content Al ₂ O ₃ /T. It is a region defined by the following conditions in a coordinate system whose coordinate axes are Fe and the mass ratio D _{2 −0.25} of particles having a diameter of 0.25 mm or less to all particles.

<Conditions for Class 1>
CB2_AT<mass ratio Al ₂ O ₃ /T. Fe < CB1_AT and mass ratio D _-0.25 < CB_Dr

<Conditions for Class 2>
CB2_AT<mass ratio Al ₂ O ₃ /T. Fe<CB1_AT and CB_Dr<mass ratio D _-0.25

Each of CB1_AT, CB2_AT and CB_Dr is a value within the following range.
0.035<CB1_AT≦0.045
0.020<CB2_AT≦0.023
10≦CB_Dr≦20

The following formula (3) can be used instead of the above formula (2).
100×Wb/(Wb+Wc)≧70 (3)

In the production of sintered ore in the first sintering machine, multiple types of iron ore can be blended so as to satisfy the conditions of the above formulas (1) and (2). On the other hand, in the production of sintered ore in a second sintering machine different from the first sintering machine, it is possible to mix a plurality of types of iron ore so as to satisfy the following formulas (4) and (5). can.
(Wb+Wc)<10 (4)
Wa<43 (5)

Wa is the mass ratio of the iron ore belonging to the third category to all the iron ore contained in the raw material for sintering. The third category is an area defined by the following conditions in the coordinate system described above.

<Conditions for Class 3>
CB1_AT<mass ratio Al ₂ O ₃ /T. Fe and mass ratio D _-0.25 < CB_Dr

A sintered ore can be produced using the raw material for sintering obtained by the blending method of the present invention. Here, when a plurality of types of iron ores are blended so as to satisfy the conditions of the above formulas (1) and (2), sintered ore can be produced in the first sintering machine. On the other hand, when multiple types of iron ores are blended so as to satisfy the conditions of the above formulas (4) and (5), sintered ore can be produced in a second sintering machine different from the first sintering machine. .

ADVANTAGE OF THE INVENTION According to this invention, the production rate of sintered ore can be improved.

It is a figure explaining the classification|category of multiple types of iron ores. FIG. 3 is a diagram showing the relationship between the total (Wb+Wc) of the blending ratio of predetermined iron ore and the content of Al ₂ O ₃ in the sintered ore. FIG. 4 is a diagram showing the relationship between the total (Wb+Wc) of predetermined iron ore blending ratios and the ratio of particles (iron ore) having a diameter of 0.25 mm or less. FIG. 3 is a diagram showing the relationship between the total mixing ratio of predetermined iron ore (Wb+Wc) and the production rate of sintered ore. FIG. 4 is a diagram showing the positional relationship between each classification region and each iron ore in the classification coordinate system.

This embodiment is a method of blending iron ore among raw materials for producing sintered ore (hereinafter referred to as sintered raw material). is blended in a predetermined blending ratio of iron ore belonging to. The production rate of sintered ore can be improved by producing sintered ore using the sintering raw material blended in this way.

(Method of Classifying Iron Ore)
A method of classifying multiple types of iron ore will be described. This classification method defines a coordinate system for classifying iron ores (hereinafter referred to as a classification coordinate system), and the classification coordinate system is represented by two coordinate axes. One coordinate axis is the mass ratio of the Al ₂ O ₃ content to the total iron (T.Fe) content (hereinafter referred to as the mass ratio Al ₂ O ₃ /T.Fe) [-] for iron ore. . The other coordinate axis is the mass ratio of iron ore (particles) with a diameter of 0.25 mm or less to all particles (hereinafter referred to as mass ratio D _−0.25 ) [mass %].

Mass ratio Al ₂ O ₃ /T. As for Fe, the content of Al ₂ O ₃ is determined by T.I. It is a value obtained by dividing by the Fe content. The mass ratio D _−0.25 is obtained by dividing the mass of particles with a diameter of 0.25 mm or less by the mass of all the particles that make up the iron ore, and multiplying this division by 100.

In this embodiment, as described above, the mass ratio Al ₂ O ₃ /T. We focus on Fe and mass ratio D _−0.25 . The reason for this will be explained below.

Chemical components of iron ore that affect the quality of sintered ore include SiO ₂ and Al ₂ O ₃ . Here, SiO ₂ is adjusted not only by the constituents contained in the iron ore, but also by the addition of auxiliary raw materials such as silica stone and peridotite. Al ₂ O ₃ is equivalent to SiO ₂ in the amount of melt generated during firing, viscosity, and influence on surface tension, and Al ₂ O ₃ is derived only from iron ore. Considering this point, it is preferable to focus on Al ₂ O ₃ instead of SiO ₂ when classifying iron ore.

On the other hand, the water of crystallization contained in the iron ore is removed by heating during sintering, and in the temperature range where the melt is generated, the components after the removal of the water of crystallization are dominant. Considering this point, instead of focusing only on Al ₂ O ₃ , T. It is preferable to focus on the ratio of the content of Al ₂ O ₃ to the content of Fe (that is, the mass ratio Al ₂ O ₃ /T.Fe).

The particle size of the iron ore affects the air permeability during firing, and the better the air permeability, the higher the firing speed (FFS: Flame Front Speed). Therefore, the grain size of iron ore is an important factor in improving the production rate of sintered ore. In the present embodiment, with regard to the particle size of the iron ore, attention is paid to particles having a diameter of 0.25 mm or less in consideration of past operational results.

In the classified coordinate system, the mass ratio Al ₂ O ₃ /T. Boundaries for classification (hereinafter referred to as classification boundaries) are set for each of Fe and mass ratio D _−0.25 . Specifically, the mass ratio Al ₂ O ₃ /T. For Fe, two classification boundaries are set and for the mass fraction D _−0.25 at least one classification boundary is set.

Mass ratio Al ₂ O ₃ /T. The first classification boundary CB1_AT for Fe is a classification boundary (mass ratio Al ₂ O ₃ /T.Fe) for distinguishing Lobe River ore and Yandicugina ore, and is higher than 0.035 [−] and 0.045 [-] Set to any value within the following range. For example, the first classification boundary CB1_AT can be set to 0.040[-].

Mass ratio Al ₂ O ₃ /T. The second classification boundary CB2_AT for Fe is a classification boundary (mass ratio Al ₂ O ₃ /T.Fe) for distinguishing Australian iron ore and South American iron ore, and is higher than 0.020 [-], It is set to any value within the range of 0.023[-] or less. The second classification boundary CB2_AT is lower than the first classification boundary CB1_AT, for example the second classification boundary CB2_AT can be 0.023.

The classification boundary CB_Dr for the mass ratio D _−0.25 is a classification boundary (mass ratio D _−0.25 ) for distinguishing pisolite iron ore from iron ores other than pisolite iron ore, and is 10 [% by mass] It is set to an arbitrary value within the range of 20 [mass %] or less. For example, the classification boundary CB_Dr can be set to 15 [mass %].

A supplemental classification boundary CB_Ds can be set for the mass fraction D _−0.25 . The classification boundary CB_Ds is a classification boundary (mass ratio D _−0.25 ) for distinguishing iron ore that has been subjected to beneficiation and iron ore that has not been subjected to beneficiation, and is 30 [mass%] or more. can be set to any value within the range of 40 [mass %] or less. For example, the classification boundary CB_Ds can be set to 35 [mass %].

In this embodiment, the mass ratio Al ₂ O ₃ /T. Classes CL1 to CL5 are defined on the basis of classification boundaries of Fe and mass fraction D _−0.25 . Specifically, the classes CL1 to CL5 are defined by the following conditions (I) to (V), respectively. FIG. 1 shows the positional relationship of classes CL1 to CL5 in the class coordinate system. The class CL2 corresponds to the first class of the present invention, the class CL3 corresponds to the second class of the present invention, and the class CL1 corresponds to the third class of the present invention.

<Condition (I) for Classification CL1>
CB1_AT<mass ratio Al ₂ O ₃ /T. Fe and mass ratio D _-0.25 < CB_Dr
<Condition (II) for Classification CL2>
CB2_AT<mass ratio Al ₂ O ₃ /T. Fe < CB1_AT and mass ratio D _-0.25 < CB_Dr
<Condition (III) of Classification CL3>
CB2_AT<mass ratio Al ₂ O ₃ /T. Fe<CB1_AT and CB_Dr<mass ratio D _-0.25
(or CB_Dr < mass ratio D _-0.25 < CB_Ds)
<Condition (IV) of Classification CL4>
Mass ratio Al ₂ O ₃ /T. Fe < CB2_AT and CB_Dr < mass ratio D _-0.25 < CB_Ds
<Condition (V) for Classification CL5>
Mass ratio Al ₂ O ₃ /T. Fe<CB2_AT and CB_Ds<mass ratio D _-0.25

In order to determine to which of the classes CL1 to CL5 an iron ore belongs, the iron ore is determined by the mass ratio Al ₂ O ₃ /T. The Fe and mass ratio D _{2 −0.25} may be obtained, and it may be determined which of the above conditions (I) to (V) applies. Mass ratio Al ₂ O ₃ /T. Regarding Fe, chemical analysis of iron ore (JIS M8202) determined T.O. Contents of Fe and Al ₂ O ₃ may be measured respectively. For the mass ratio D _-0.25 , particles with a diameter of 0.25 mm or less are sieved (JIS M8706), and the mass of iron ore (all particles) before sieving and the diameter is 0.25 mm or less It is sufficient to measure the mass of the particles.

(Combination conditions of iron ore)
Next, blending conditions for blending a plurality of types of iron ore to produce sintered ore will be described. Here, the mixing ratio of iron ore belonging to class CL1 is Wa [mass%], the mixing ratio of iron ore belonging to class CL2 is Wb [mass%], and the mixing ratio of iron ore belonging to class CL3 is Wc [mass%]. and Each of the mixing ratios Wa, Wb, and Wc is the ratio of the mass of iron ore belonging to each class to the mass of all iron ores blended.

The iron ore belonging to Class CL2 and the iron ore belonging to Class CL3 are blended so as to satisfy the following formulas (1) and (2).
74≦(Wb+Wc) (1)
100×Wb/(Wb+Wc)≧50 (2)

Regarding the above formulas (1) and (2), the mixing ratio Wc may be 0 [mass %], and the iron ore belonging to class CL3 may be omitted. By blending the iron ore belonging to Class CL2 and Class CL3 so as to satisfy the conditions of the above formulas (1) and (2), the production rate of sintered ore can be improved. The reason for this will be explained below.

FIG. 2 shows the relationship between the Al ₂ O ₃ content [mass %] in the sintered ore and “Wb+Wc”. Note that the black circles shown in FIG. 2 are values corresponding to normal operating conditions, and are used as references for the content of Al ₂ O ₃ in this embodiment. Here, the lower the Al ₂ O ₃ content, the easier it is to improve the yield of the sintered ore.

In FIG. 2, when "Wb+Wc" is 74 [mass %] or more, the behavior of the content of Al ₂ O ₃ changes according to the magnitude relationship between the compounding ratios Wb and Wc. When the blending ratios Wb and Wc are equal to each other, or when the blending ratio Wb is lower than the blending ratio Wc, the content of Al ₂ O ₃ in the sintered ore remains almost unchanged even if “Wb+Wc” changes. On the other hand, when the mixture ratio Wb is higher than the mixture ratio Wc, the more "Wb+Wc" increases from 74 [mass %], the more the content of Al ₂ O ₃ in the sintered ore decreases.

FIG. 3 shows the relationship between the mass ratio D _−0.25 and “Wb+Wc”. The black circles shown in FIG. 3 are values corresponding to normal operating conditions, and in this embodiment, the mass ratio D _{1 −0.25} is used as the standard. Here, the lower the mass ratio D _-0.25 , the easier it is to improve the air permeability during firing.

In FIG. 3, when “Wb+Wc” is 74 [mass %] or more, the behavior of the mass ratio D _−0.25 changes according to the magnitude relationship of the compounding ratios Wb and Wc. When the blending ratio Wb is lower than the blending ratio Wc, the mass ratio D _−0.25 increases as “Wb+Wc” increases from 74 [mass %]. When the mixture ratios Wb and Wc are equal to each other, or when the mixture ratio Wb is higher than the mixture ratio Wc, the mass ratio D _-0.25 decreases as "Wb+Wc" increases from 74 [mass %].

FIG. 4 shows the relationship between the production rate of sintered ore and "Wb+Wc". The black circles shown in FIG. 4 are values corresponding to normal operating conditions, and are used as a reference for the production rate in this embodiment. Here, the sintered ore production rate depends on the yield and air permeability described above. Specifically, the interaction of yield and air permeability determines the production rate of sinter. For example, if both the yield and air permeability are improved, the production rate of sintered ore is improved, and if both the yield and air permeability are deteriorated, the production rate of sintered ore is lowered.

In FIG. 4, when "Wb+Wc" is 74 [mass %] or more, the behavior of the production rate changes according to the magnitude relationship between the compounding ratios Wb and Wc. In the following, the magnitude relationship between the compounding ratios Wb and Wc will be described separately for each case.

As shown in FIG. 4, when the blending ratio Wb is lower than the blending ratio Wc, in other words, when "100×Wb/(Wb+Wc)" is less than 50, "Wb+Wc" increases from 74 [% by mass]. the more the production rate decreases. When the blending ratio Wb is lower than the blending ratio Wc, the content of Al ₂ O ₃ (in other words, the yield of sintered ore) is difficult to change as shown in FIG. D _-0.25 rises and air permeability tends to deteriorate. Here, since the effect of deterioration of air permeability becomes remarkable, as a result of the interaction of yield and air permeability, as shown in FIG. will decline.

As shown in FIG. 4, when the blending ratios Wb and Wc are equal to each other, in other words, when “100×Wb/(Wb+Wc)” is 50, the more “Wb+Wc” increases from 74 [mass %], the more the production rate improves. When the mixing ratios Wb and Wc are equal to each other, the content of Al ₂ O ₃ (in other words, the yield of sintered ore) is difficult to change as shown in FIG. 2, and the mass ratio D _{− 0.25} is lowered and the air permeability is easily improved. Here, since the effect of improving air permeability becomes remarkable, as a result of the interaction of yield and air permeability, as shown in FIG. will improve.

As shown in FIG. 4, when the mixture ratio Wb is higher than the mixture ratio Wc, in other words, when "100×Wb/(Wb+Wc)" is higher than 50, "Wb+Wc" increases from 74 [% by mass]. The higher the productivity, the better. When the blending ratio Wb is higher than the blending ratio Wc, the content of Al ₂ O ₃ decreases as shown in FIG. D _-0.25 is lowered and the air permeability is easily improved. Here, since both the yield and the air permeability are improved, as a result of the interaction of the yield and the air permeability, as shown in FIG. will improve. Here, when "Wb+Wc" has the same value, the production rate when the mixing ratio Wb is higher than the mixing ratio Wc is higher than the production rate when the mixing ratios Wb and Wc are equal to each other.

For the reasons described above, the production rate of sintered ore can be improved by blending iron ore belonging to Class CL2 and Class CL3 so as to satisfy the conditions of the above formulas (1) and (2).

On the other hand, it is preferable to set the condition of the following formula (3) as the condition of the above formula (2).
100×Wb/(Wb+Wc)≧70 (3)

By blending the iron ore so as to satisfy the conditions of the above formulas (1) and (3), the phosphorus content in the sintered ore can be reduced. By reducing the phosphorus content, the load of dephosphorization treatment in steelmaking can be reduced.

Next, as shown in the above formula (1), when "Wb + Wc" is set to 74 [mass%] or more, iron ore belonging to classifications CL2 and CL3 is actively used, and iron ores belonging to other classifications CL1, CL4, and CL5 are actively used. iron ore belonging to Therefore, the iron ore can be blended so as to satisfy the conditions of the above formulas (1) and (2), while the iron ore can be blended so as to satisfy the following formulas (4) and (5). . In addition, even if the multiple types of iron ores that serve as sintering raw materials do not satisfy the conditions of the above formulas (1) and (2), and do not satisfy the following formulas (4) and (5), , these iron ores are sorted into a plurality of types of iron ores satisfying the conditions of the above formulas (1) and (2) and a plurality of types of iron ores satisfying the following formulas (4) and (5). be able to.

(Wb+Wc)<10 (4)
Wa<43 (5)

Regarding the above formula (5), the mixing ratio Wa may be 0 [mass %], and the iron ore belonging to the class CL1 may be omitted. By blending the iron ores belonging to the classifications CL1, CL2, and CL3 so as to satisfy the conditions of the above formulas (4) and (5), the production rate of sintered ore can be improved. The reason for this will be explained below.

In FIG. 2, when "Wb+Wc" is less than 10 [mass %], the behavior of the content of Al ₂ O ₃ changes according to the mixing ratio Wa. When the blending ratio Wa is 43 [mass%] or lower than 43 [mass%], the content of Al ₂ O ₃ decreases as “Wb + Wc” decreases from 10 [mass%]. decreases. On the other hand, when the mixing ratio Wa is higher than 43 [mass %], the content of Al ₂ O ₃ increases as "Wb+Wc" decreases from 10 [mass %].

In FIG. 3, when “Wb+Wc” is less than 10 [mass %], the behavior of the mass ratio D _−0.25 changes according to the mixing ratio Wa. When the mixture ratio Wa is 43 [mass%] or is lower than 43 [mass%], the mass ratio D decreases _{to -0.25} as “Wb+Wc” decreases from 10 [mass%]. rises. On the other hand, when the blending ratio Wa is higher than 43 [mass %], the mass ratio D _−0.25 decreases as “Wb+Wc” decreases from 10 [mass %].

In FIG. 4, when "Wb+Wc" is less than 10 [mass %], the behavior of the production rate changes according to the mixing ratio Wa. Hereinafter, the blending ratio Wa will be described separately for each case.

As shown in FIG. 4, when the mixing ratio Wa is higher than 43 [mass %], the production rate decreases as "Wb+Wc" decreases from 10 [mass %]. When the blending ratio Wa is higher than 43 [mass%], the content of Al ₂ O ₃ increases as shown in FIG. 2 and the yield of sintered ore tends to decrease, while as shown in FIG. In addition, the mass ratio D _−0.25 is lowered, and the air permeability is easily improved. Here, since the effect of lowering yield is higher than the effect of improving air permeability, as a result of the interaction of yield and air permeability, "Wb + Wc" decreases from 10 [mass%] as shown in FIG. The more you do, the lower your productivity will be.

As shown in FIG. 4, when the mixing ratio Wa is 43 [mass %], even if "Wb+Wc" changes, the production rate hardly changes. When the blending ratio Wa is 43 [mass%], the content of Al ₂ O ₃ decreases as shown in FIG. 2 and the yield of sintered ore tends to improve, while as shown in FIG. The mass ratio D _−0.25 increases, and the air permeability tends to deteriorate. Here, since the effect of improving the yield and the effect of deteriorating the air permeability are offset, as a result of the interaction of the yield and the air permeability, as shown in FIG. 4, even if "Wb + Wc" changes, the production rate becomes difficult to change.

As shown in FIG. 4, when the blending ratio Wa is lower than 43 [mass %], the productivity improves as "Wb+Wc" decreases from 10 [mass %]. When the blending ratio Wa is lower than 43 [mass%], the content of Al ₂ O ₃ decreases as shown in FIG. In addition, the mass ratio D _-0.25 increases, and the air permeability tends to deteriorate. Here, since the effect of improving yield is higher than the effect of deteriorating air permeability, as a result of the interaction of yield and air permeability, "Wb + Wc" decreases from 10 [mass%] as shown in FIG. The more you do, the better your productivity will be.

For the reasons described above, the production rate of sintered ore can be improved by blending iron ores belonging to the categories CL1 to CL3 so as to satisfy the conditions of the above formulas (4) and (5).

A plurality of types of iron ores A to L were prepared. The chemical components and particle size distribution of each iron ore A to L are shown in Table 1 below.

Regarding the chemical composition of iron ores A to L, T. Fe, SiO ₂ , Al ₂ O ₃ , CW and P were measured according to JIS M8202. Mass ratio Al ₂ O ₃ /T. Fe is T.I. It was calculated from the measurement results of Fe and Al ₂ O ₃ .

Regarding the particle size distribution, the mass ratio D ₋₁ of particles with a diameter of 1 mm or less to all particles and the mass ratio D _−0.25 of particles with a diameter of 0.25 mm or less to all particles were measured. The mass of particles with a diameter of 1 mm or less and the mass of particles with a diameter of 0.25 mm or less were measured according to JIS M8706.

For each iron ore A to L, the mass ratio Al ₂ O ₃ /T. By obtaining Fe and the mass ratio D _−0.25 , the classification to which each iron ore A to L belongs was determined based on the above conditions (I) to (V). Table 1 above also shows the classification to which each iron ore A to L belongs. FIG. 5 also shows the positional relationship between the areas of classifications CL1 to CL5 and the respective iron ores A to L in the classification coordinate system. In this embodiment, the first classification boundary CB1_AT is 0.040 [-], the second classification boundary CB2_AT is 0.023 [-], the classification boundary CB_Dr is 15 [% by mass], and the classification boundary CB_Ds is 35 [ % by mass].

Table 2 below shows the sintering raw materials (iron ore, limestone and peridotite) and the mixing ratio of the sintering raw materials. In Examples 1-3, Comparative Examples 1-4, and Reference Examples 1-2, the mixing ratios of iron ores A to L are different, and the mixing ratios of limestone and peridotite are the same. In addition to the raw materials for sintering shown in Table 2 below, 15 [% by mass] (outside number) of return ore and 4.5 [% by mass] (outside number) of carbonaceous materials were blended.

A sintering pot test was performed for Examples 1-3, Comparative Examples 1-4, and Reference Examples 1-2. In the sintering pot test, first, a cylindrical sintering pot having an arbitrary diameter and height was filled with sintering raw materials. Here, after setting sintered ore (2.0 kg) as a bedding in a sintering pot, the bedding was filled with sintering raw materials. Then, the surface of the sintering raw material layer in the sintering pot was ignited, and air was sucked by a blower from an air box installed at the bottom of the sintering pot. This makes it possible to simulate the sintering process in the sintering raw material layer.

In this example, a sintering pot with a diameter of 300 mm and a height of 500 mm was used. Sintering was started by igniting the surface of the sintering raw material layer in the sintering pot with a burner for 1 minute while sucking air at a negative pressure of 9.8 kPa. The temperature of the exhaust gas was continuously measured by a temperature sensor installed in the wind box, and sintering was terminated when 3 minutes had passed since the temperature of the exhaust gas reached the maximum value. After manufacturing the sintered ore, the chemical components (SiO ₂ , Al ₂ O ₃ , P) contained in the sintered ore were measured, and the production rate, yield and FFS of the sintered ore were determined.

The production rate of sintered ore is a value obtained by dividing the weight of sintered ore, which is a product, by the sintering time, and dividing this division value by the bottom area of the sintering pot. Here, the sintering time was defined as the time from the time when ignition of the surface of the sintering raw material layer was started to the time when the temperature of the exhaust gas reached the maximum value.

The yield of sintered ore was calculated as follows. After dropping the sintered cake four times from a height of 2.0 m, the dropped objects were classified with a sieve (5 mm in diameter), and the weight of the bedding (2.0 kg) was subtracted from the weight on the sieve. The value was taken as the weight of the sintered ore. The yield was obtained by dividing the weight of the sintered ore by the weight of the cake minus the weight of the bedding (2.0 kg).

FFS is a value obtained by dividing the layer thickness of the sintering raw material layer (the size of the sintering pot in the height direction) when the sintering raw material is filled in the sintering pot, by the sintering time.

Table 3 below shows the chemical components (SiO ₂ , Al ₂ O ₃ , P) in the sintered ore and the production rate of the sintered ore for Examples 1 to 3, Comparative Examples 1 to 4, and Reference Examples 1 and 2. , yield and FFS. Further, Table 3 below shows “Wb+Wc”, “100×Wb/(Wb+Wc)” and Wa in the above formulas (1) to (3), and also shows the mass ratio D _−0.25 .

According to the results shown in Table 3 above, Examples 1-3 improved the productivity more than Comparative Examples 1-4.

Regarding Comparative Examples 1 and 2, when "Wb+Wc" was increased from 47.6 [mass%] to 68.3 [mass%], Al ₂ O ₃ in the sintered ore increased and the yield decreased. On the other hand, in Comparative Examples 1 and 2, the FFS increased as the mass ratio D _-0.25 decreased from 21.3 [mass%] to 17.5 [mass%]. Here, the production rate of Comparative Example 2 was lower than the production rate of Comparative Example 1 because the influence of yield was greater than the influence of FFS.

As described above, when “Wb + Wc” is increased from 47.6 [mass%] to 68.3 [mass%], Al ₂ O ₃ in the sintered ore increases, but Comparative Example 3 and Example 1 According to ~3, it was found that Al ₂ O ₃ in the sintered ore started to decrease when "Wb + Wc" was 74 [mass%] or more. In particular, when "Wb + Wc" is 90 [mass%] or more, as can be seen from Comparative Example 3 and Examples 2 and 3, Al ₂ O ₃ in the sintered ore tends to decrease, and the yield is improved. .

Even if "Wb+Wc" is 74 [mass %] or more, the production rate changes depending on whether "100×Wb/(Wb+Wc)" is 50 or more. In Comparative Example 3, although the condition of the above formula (1) was satisfied, the condition of the above formula (2) was not satisfied, and the production rate was 28.1 [t/d/m ² ]. In Examples 2 and 3, both the conditions of the above formulas (1) and (2) are satisfied, and the production rate is 30.5 [t/d/m ² ], which is significantly higher than that of Comparative Example 3. rose to In Comparative Example 4, both conditions of the above formulas (1) and (2) were not satisfied, and the production rate was 22.6 [t/d/m ² ], which was the lowest.

Examples 1 and 2 satisfy both conditions of the above formulas (1) and (2), but Example 3 satisfies both of the above conditions (1) and (3). According to Example 3, by setting "100×Wb/(Wb+Wc)" to 70 or more, compared to Examples 1 and 2, phosphorus contained in the sintered ore could be reduced. Thereby, the load of the dephosphorization process in steelmaking can be reduced.

When "Wb+Wc" is less than 10 [mass%], the production rate changes depending on whether Wa is less than 43 [mass%]. In Reference Example 2, the condition of formula (4) was satisfied, but the condition of formula (5) was not satisfied, and the production rate was 26.5 [t/d/m ² ]. In Reference Example 1, both conditions of the above formulas (4) and (5) are satisfied, and the production rate is 28.9 [t/d/m ² ], which is significantly higher than in Reference Example 2. bottom.

From the above results, in an ironworks having two sintering machines, the raw material composition does not satisfy the conditions of the above formulas (1) and (2), and the above formulas (4) and (5) Even if the conditions of are not satisfied, multiple types of iron ore are prepared in the first sintering machine so as to satisfy the conditions of the above formulas (1) and (2), or the above formulas (1) and (3). While blending, a plurality of types of iron ore are blended in a second sintering machine different from the first sintering machine so that the conditions of the above formulas (4) and (5) are satisfied, so that two sintering machines It is clear that the productivity is improved as compared with the case where the sintering raw materials used in are of the same raw material composition.

Claims (5)

A sintering raw material blending method characterized by blending a plurality of types of iron ore so as to satisfy the following formulas (1) and (2).
74≦(Wb+Wc) (1)
100×Wb/(Wb+Wc)≧50 (2)
Wb is the mass ratio of the iron ore belonging to the first category to all the iron ore contained in the sintering raw material,
Wc is the mass ratio of iron ore belonging to the second category to all the iron ore contained in the sintering raw material,
The first class and the second class are based on the mass ratio of alumina content to total iron content Al ₂ O ₃ /T. It is a region defined by the following conditions in a coordinate system whose coordinate axes are Fe and the mass ratio D _{2 −0.25} of particles having a diameter of 0.25 mm or less to all particles.
<Conditions for Class 1>
CB2_AT<mass ratio Al ₂ O ₃ /T. Fe < CB1_AT and mass ratio D _-0.25 < CB_Dr
<Conditions for Class 2>
CB2_AT<mass ratio Al ₂ O ₃ /T. Fe<CB1_AT and CB_Dr<mass ratio D _-0.25
Each of CB1_AT, CB2_AT and CB_Dr is a value within the following range.
0.035<CB1_AT≦0.045
0.020<CB2_AT≦0.023
10≦CB_Dr≦20 2. The method of blending raw materials for sintering according to claim 1, wherein the condition of the following formula (3) is satisfied.
100×Wb/(Wb+Wc)≧70 (3) In the production of sintered ore in the first sintering machine, multiple types of iron ore are blended so as to satisfy the conditions of the above formulas (1) and (2),
In the production of sintered ore in a second sintering machine different from the first sintering machine, a plurality of types of iron ore are blended so as to satisfy the following formulas (4) and (5). The method of blending raw materials for sintering according to claim 1 or 2.
(Wb+Wc)<10 (4)
Wa<43 (5)
Wa is the mass ratio of iron ore belonging to the third category to all the iron ore contained in the sintering raw material,
The third category is an area defined by the following conditions in the coordinate system.
<Conditions for Class 3>
CB1_AT<mass ratio Al ₂ O ₃ /T. Fe and mass ratio D _-0.25 < CB_Dr A method for producing sintered ore, comprising producing sintered ore using the sintering raw material obtained by the blending method according to claim 1 or 2. Sintered ore characterized by producing sintered ore in each of the first sintering machine and the second sintering machine using the sintering raw material obtained by the blending method according to claim 3. Production method.

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