JP2008088476A - Method for operating blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for operating a blast furnace, which can further improve both air permeability in the blast furnace and reduction efficiency for ore compared to those in a conventional method, by integrally reviewing the technology of producing cokes and using them in the blast furnace. <P>SOLUTION: This technology of producing the cokes comprises the steps of: separately producing high-reactivity low-strength cokes (A) and low-reactivity high-strength cokes (B) in a coke oven (1); preparing small grains (A<SB>2</SB>) of the high-reactivity low-strength cokes by regulating the particle size of the high-reactivity low-strength cokes (A); and preparing large lumps (B<SB>1</SB>) of the low-reactivity high-strength cokes and small grains (B<SB>2</SB>) of the low-reactivity high-strength cokes by regulating the particle size of the low-reactivity high-strength cokes (B). The operation method comprises the steps of: preparing a mixture (D) by mixing the small grains (A<SB>2</SB>) of the high-reactivity low-strength cokes and the small grains (B<SB>2</SB>) of the low-reactivity high-strength cokes with ores (C); and alternately charging the mixture (D) and the large lump (B<SB>1</SB>) of the low-reactivity high-strength cokes into the blast furnace (6). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for operating a blast furnace in which hot metal is produced using coke produced in a coke oven as a reducing material.

  In recent years, coke for blast furnaces having high strength and high reactivity has been desired in order to improve both blast furnace air permeability and ore reduction efficiency to improve blast furnace operation. However, in general, the properties of coke produced in a chamber-type coke oven (hereinafter simply referred to as “coke oven”) have a negative correlation between strength and reactivity. It is difficult to increase. That is, when the caking coal ratio of the blended coal, which is a coke raw material, is increased, the strength of the coke is increased, but the reactivity is lowered, and the use ratio of expensive caking coal is increased, resulting in an increase in cost. On the contrary, when the non-slightly caking coal ratio is increased, the reactivity is increased, and the use ratio of inexpensive non-slightly caking coal is increased, so that the cost is reduced, but the strength is lowered.

On the other hand, the coke produced in the coke oven is sieved for each predetermined particle size, and the coke of each particle size is charged into different locations in the blast furnace, thereby improving the air permeability and ore reducibility in the blast furnace and improving the blast furnace operation. Many methods to be improved are disclosed (for example, refer to Patent Documents 1 to 8). However, in these conventional technologies, since coke produced by using a coke raw material (mixed coal) with a certain blending condition in a coke oven is simply sieved, strength and reaction are different even if the particle size is different. Since the property itself does not change, there is a problem that the coke having the optimum property is not always charged in each charging place of the blast furnace, and the above improvement effect cannot be obtained sufficiently.
JP-A-7-286203 Japanese Patent No. 2752502 Japanese Patent No. 2769835 JP 57-174403 A JP 2004-307928 A Japanese Patent Laid-Open No. 2001-279307 Japanese Patent No. 3485787 JP-A-6-264118

  The present invention has been made in view of such problems. By reviewing the coke production technology and the technology used in the blast furnace, both the air permeability in the blast furnace and the reduction efficiency of the ore are further improved over the conventional method. It aims to provide a possible blast furnace operation method.

The invention described in claim 1 is a blast furnace operating method for producing hot metal using coke produced in a coke oven as a reducing material, comprising the following steps [1] to [5]: It is a blast furnace operation method.
[1] Coke production process for producing high-reactivity low-strength coke (A) and low-reactivity high-strength coke (B) in the coke oven [2] Particle size adjustment of the high-reactivity low-strength coke (A) First sizing step of preparing a small-grain high-reactivity low-strength coke (A ₂ ) [3] The low-reactivity high-strength coke (B) is sized to provide a large mass low-reactivity high-strength coke (B ₁ ) And small grain low reactivity high strength coke (B ₂ ) [4] The small grain high reactivity low strength coke (A ₂ ) and the small grain low reactivity high strength coke (B ₂ ) Mixing step to mix in ore (C) to form mixture (D) [5] This mixture (D) and the large mass low-reactivity high-strength coke (B ₁ ) are alternately charged into the blast furnace. The charging process.

The invention according to claim 2 is characterized in that the reactivity index CRI of the high reactivity low strength coke (A) exceeds 30 and the difference from the CRI of the low reactivity high strength coke (B) is 5 or more. and wherein said in claim 1, a difference of 0.5 or more and ^DI _{0.99 15} low reactivity high strength coke (B) of the drum strength index ^DI _{0.99 15} and the high reactivity low strength coke (a) This is the blast furnace operation method.

According to a third aspect of the invention, so as to satisfy the following formula 1, wherein adjusting the charging amount _{W A2 [kg / t-pig} ] of the small highly reactive low strength coke to the blast furnace (A ₂₎ Item 3. A blast furnace operating method according to Item 1 or 2.
Formula _{1 W A2 ×% C A /} 100 ≦ C SL + C C -W B2 ×% C B / 100-W PC × (1-% Ash PC / 100) × (1-% BR PC / 100)
Here,% C _A is the C content [% by mass] of the high-reactivity low-strength coke (A), C _SL is the solution loss C amount [kg / t-pig] in the blast furnace, and C _C is in the hot metal C content _{[kg / t-pig],} W B2 is the charging amount to the blast furnace of the low reactivity high strength coke _{(B 2) [kg / t} -pig],% C B is the low reactivity and high Strength Coke (B) C content [% by mass], W _PC is the pulverized coal ratio in the blast furnace [kg / t-pig],% Ash _PC is the ash content of the pulverized coal [% by mass],% BR _PC is the above It is the combustion rate [%] in the raceway of pulverized coal.

In the invention according to claim 4, the charging amount W _A2 [kg / t-pig of the high-reactivity low-strength coke (A ₂ ) into the blast furnace so that the following formula 2 is satisfied instead of the formula 1. ] Is a blast furnace operating method according to claim 3.
Formula _{2 W A2 ×% C A /} 100 ≦ C SL -W B2 ×% C B / 100-W PC × (1-% Ash PC / 100) × (1-% BR PC / 100)

  In the invention according to claim 5, when the proportion of non-slightly caking coal relative to the total amount of coal used in the coke oven is X mass%, the blending ratio of the non-slightly caking coal is higher than X mass%. The blended coal (P) and the blended coal (Q) in which the blending ratio of the non-slightly caking coal is lower than X mass% are prepared, and these blended coals (P and Q) are separated from each other in the coke oven. The high-reactivity low-strength coke (A) and the low-reactivity high-strength coke (B) are separately formed by charging in a carbonization chamber and dry distillation. It is a blast furnace operation method.

  According to the blast furnace operation method of the present invention, by introducing coke having suitable properties to each predetermined charging place in the blast furnace, both the blast furnace air permeability and the ore reduction efficiency are further improved over the conventional method. As a result, further stabilization and efficiency of blast furnace operation can be realized.

  As described above, the present invention includes the following steps [1] to [5].

[1] Coke production process for producing high-reactivity low-strength coke (A) and low-reactivity high-strength coke (B) in the coke oven [2] Particle size adjustment of the high-reactivity low-strength coke (A) First sizing step of preparing a small-grain high-reactivity low-strength coke (A ₂ ) [3] The low-reactivity high-strength coke (B) is sized to provide a large mass low-reactivity high-strength coke (B ₁ ) And small grain low reactivity high strength coke (B ₂ ) [4] The small grain high reactivity low strength coke (A ₂ ) and the small grain low reactivity high strength coke (B ₂ ) Mixing step to mix in ore (C) to form mixture (D) [5] This mixture (D) and the large mass low-reactivity high-strength coke (B ₁ ) are alternately charged into the blast furnace. The charging process.

Embodiment
Hereafter, each said process is demonstrated in detail, referring drawings. FIG. 1 is a flowchart for explaining a hot metal production process including a coke oven and a blast furnace according to an embodiment of the present invention.

-Coke production process In this process, a high-reactivity low-strength coke (A) and a low-reactivity high-strength coke (B) are separately produced in a coke oven (1).

  Here, the high-reactivity low-strength coke (A) is used for the purpose of improving the reducibility of the ore by mixing with ores, so that the reactivity is desired to be as high as possible. On the other hand, it is sufficient if the strength is ensured to such an extent that it is not excessively pulverized, and the strength is not as high as that of ordinary coke used as a spacer.

  On the other hand, the low-reactivity high-strength coke (B) plays a role of a spacer for ensuring air permeability in the blast furnace mainly as a lump coke. The reactivity is not so required due to the coexistence of the high-reactivity low-strength coke (A), and can be made lower than that of ordinary coke.

From the above viewpoint, the reactivity index CRI of the highly reactive low strength coke (A) is preferably higher than that of ordinary coke, more than 30, more preferably 35 or more, particularly 40, and the low reactivity high strength coke. It is preferably 5 or more, more preferably 10 or more higher than the CRI of (B). Here, the CRI is the mass reduction rate (expressed in%) of coke when 200 g of coke having a particle size of 20 ± 1 mm is reacted at 1100 ° C. for ₂ hours by flowing CO ₂ gas at a flow rate of 5 NL / min. Say.

On the other hand, the drum strength index ^DI _{0.99 15} low reactivity high strength coke (B) is, ^DI _{0.99 15} than 0.5 or more highly reactive low strength coke (A), more preferably higher than 1.0 . Here, DI ¹⁵⁰ ₁₅ refers to the mass ratio (expressed in%) of a lump of 15 mm or more after 150 revolutions in a drum tester according to JIS K2151.

  The two types of coke (A and B) can be separately produced in the coke oven (1) as follows, for example. That is, when the purchase ratio of caking coal (L) and non-slightly caking coal (M) of all purchased coal is fixed, it is non-slight with respect to the total amount of purchased coal (L + M) used in the coke oven (1). When the use ratio of caking coal (M) is X mass%, the blending charcoal (P) in which the blending ratio of non-minor caking coal (M) is higher than X mass%, and non-minor caking coal (M) The blended coal (Q) with a blending ratio of less than X mass% is prepared at a predetermined ratio, and these blended coals (P and Q) are charged into separate carbonization chambers of the coke oven (1) and dry-distilled. do it. Thereby, a high-reactivity low-strength coke (A) can be produced from the coal blend (P), and a low-reactivity high-strength coke (B) can be produced from the coal blend (Q).

  Here, since the high-reactivity low-strength coke (A) is pulverized by pulverization or the like in the first sizing process described later, the coal blend (P) is subjected to dry distillation to obtain the high-reactivity low-strength coke (A). In the carbonization chamber to be manufactured, the furnace temperature may be raised compared to the prior art, and the coke after dry distillation may be refined in advance. On the other hand, the low-reactivity high-strength coke (B) is mainly used in a large mass as will be described in the second sizing step described later. In the carbonizing chamber for producing the above, it is preferable to keep the furnace temperature the same as or slightly lower than that of the conventional one so as to suppress the atomization.

· In the first granule sizing step this step, the coke oven as described above highly reactive low strength coke produced in (1) (A) and then sized small highly reactive low strength coke (A ₂₎ To prepare.

Here, the small high-reactivity low-strength coke (A ₂ ) refers to one that has been reduced to the same particle size as ores, and the lower limit of the particle size range is the lower limit size that does not fluidize by blast furnace gas. The upper limit is about 40 mm, preferably about 30 mm, and more preferably about 20 mm, which is almost the same as the upper limit of ores.

In order to prepare such a particle size, for example, high-reactivity low-strength coke (A) is sized by combining a crusher (2) and a sieve (3), and a small high-reactivity low-strength coke (A ₂ ) is placed on the sieve. ) And the coke under the low-reactivity high-strength coke (to be described later) together with powder coke (F) and used as a solid fuel for the production of sintered ore by a sintering machine.

[3] Second grain sizing step In this step, the low-reactivity high-strength coke (B) is sized to make a large mass low-reactivity high-strength coke (B ₁ ) and small-grain low-reactivity high-strength coke (B ₂ ). And prepare.

Here, the large mass low-reactivity high strength coke (hereinafter also simply referred to as “large mass coke”) (B ₁ ) is one having a particle size equivalent to that of ordinary mass coke (for example, a particle size of 40 to 100 mm). The small low-reactivity high-strength coke (B ₂ ) refers to one having a smaller particle size (particle size equivalent to the above-mentioned small high-reactivity low-strength coke (A ₂ )).

In order to prepare such a particle size, the low-reactivity high-strength coke (B) is sized using a two-stage sieve (4 and 5) as before, and a large mass low-reactivity high-strength on each sieve. Coke (B ₁ ) and small-grain low-reactivity high-strength coke (B ₂ ), and the sieve under the above-mentioned high-reactivity low-strength coke (B) and powder coke (F). It is used as a solid fuel.

[4] Mixing step In this step, small high-reactivity low strength coke (A ₂ ) and small low-reactivity high strength coke (B ₂ ) prepared in the first and second sizing steps (collectively referring to these) (Referred to as “small coke”) in the ore (C) to form a mixture (D).

  Here, the ores refer to those containing slag ore such as limestone and quartzite as necessary, in addition to ores such as sintered ore, pellets and lump ore.

The mixing of the small coke (A ₂ and B ₂ ) into the ore (C) can be performed, for example, by cutting out a predetermined amount of each on a belt conveyor as in the conventional case.

Here, the amount of small coke (A ₂ and B ₂ ) mixed into the ore (C), in other words, the amount of small coke (A ₂ and B ₂ ) charged into the blast furnace [kg / t-pig] Can be determined as follows. That is, first, the small-sized low-reactivity high-strength coke (B ₂ ) is automatically determined because the entire amount obtained by sieving in the second sizing step is used. Next, the charging amount W _A2 [kg / t-pig] of the small high-reactivity low-strength coke (A ₂ ) into the blast furnace (6) is determined so as to satisfy the following formula 1.

Formula _{1 W A2 ×% C A /} 100 ≦ C SL + C C -W B2 ×% C B / 100-W PC × (1-% Ash PC / 100) × (1-% BR PC / 100)
Here,% C _A is the C content [% by mass] of the highly reactive low strength coke (A), C _SL is the solution loss C amount [kg / t-pig] in the blast furnace (6), and C _C is in the hot metal C content of _{[kg / t-pig],} W B2 is charging amount to the blast furnace (6) of small low-reactive high-strength coke _{(B 2) [kg / t} -pig],% C B is less reactive C content of high strength coke (B ₂ ) [% by mass], W _PC is the pulverized coal ratio in the blast furnace [kg / t-pig],% Ash _PC is the ash content of the pulverized coal [% by mass],% BR _PC is the combustion rate [%] of the pulverized coal in the raceway.

The above equation 1 is derived from the following concept. That is, in the blast furnace (6), the carbon source used for the solution reaction and carburizing of the hot metal is preferentially consumed from the carbon material having a small particle size, and after they are consumed up, the largest particle size is obtained. Large coke is consumed. Therefore, blast furnace (6) C content in solution loss C content _{C SL} and the hot metal in (i.e., carburization amount) from the total amount of _{C C,} C content in the small particle coke _{(A 2} and C content of _{B 2} of The total amount) and the amount of C in the portion of pulverized coal blown from the tuyere that has not burned in the raceway and has left the raceway unburned (unburned in the raceway) The remaining [C _SL − (W _A2 ×% C _A / 100 + W _B2 ×% C _B / 100) −W _PC × (1-% Ash _PC / 100) × (1-% BR _PC / 100)] is large. This corresponds to the amount of C consumed from the bulk coke (B ₁ ). Therefore, by increasing the charging amount of the small particle coke (A _2), the large lump coke (B ₁₎ can be reduced as much as possible the amount of C consumed by the large lump coke (B ₁₎ Is suppressed, and the air permeability and liquid permeability in the blast furnace can be improved. However, if the charging amount of the small coke (A ₂ ) is excessive, the C consumption due to the solution loss of the large coke (B ₁ ) is eliminated, but the small coke (A ₂ and / or B ₂ ) is consumed. Since it remains without cutting and the ratio of the reducing material increases, the amount of C consumed from the large coke (B ₁ ) [C _SL − (W _A2 ×% C _A / 100 + W _B2 ×% C _B / 100) −W _PC × (1-% Ash _PC / 100) × (1-% BR _PC / 100)] ≧ 0, that is, WA ₂ ×% C _A / 100 ≦ C _SL −W _B2 ×% C and thus it is preferable to adjust the charging amount _{W A2} of the small coke _{(a 2)} in the range of _{B / 100-W PC × (} 1-% Ash PC / 100) × (1-% BR PC / 100) .

[5] Charging step In this step, the mixture (D) in which the blending ratio of the fine coke (A ₂ and B ₂ ) to the ore (C) is adjusted as described above, and the large mass low-reactivity high strength Coke (B ₁ ) and the blast furnace (6) are alternately charged.

As a result, although the mixture (D) forms an ore layer, the reduction efficiency of the ore is further improved as compared with the conventional method by mixing highly reactive small coke (A ₂ ) in the ore layer. In addition, the large mass low-reactivity high strength coke (B ₁ ) forms a coke layer. The large mass coke (B ₁ ) itself has high strength, and in addition to the small coke ( Since the deterioration due to the solution loss or the like is suppressed by the preferential consumption of A ₂ ), the air permeability in the blast furnace is further improved than before.

(Modification)
In the above embodiment, the charging amount of the blast furnace having a small particle coke (A ₂₎ is an example in which the range satisfying the above formula 1, may be in the range satisfying the following formula 2 in place of this.

Formula _{2 W A2 ×% C A /} 100 ≦ C SL -W B2 ×% C B / 100-W PC × (1-% Ash PC / 100) × (1-% BR PC / 100)

The above formula 2 is obtained by excluding the carburized amount C _C to the molten iron from the formula 1. That is, the large coke (B ₁ ) forms the core coke, and is eventually consumed by carburizing in the hot metal, so this carburized content is transferred to the large coke (B ₁ ). In this case, only the solution loss reaction component is taken into consideration because it does not significantly affect the deterioration of the large block coke (B ₁ ).

Further, in the above embodiment, the high-reactivity low-strength coke (A) and the low-reactivity high-strength coke (B) are separately produced by dry distillation of blended coals having different compositions using only a chamber furnace in separate carbonization chambers. However, a high-reactivity low-strength coke (A) may be manufactured by a molding coke method, and a low-reactivity high-strength coke (B) may be manufactured in a chamber furnace. Since the coke having a desired particle size can be directly produced by using the molded coke method, a granulated coke production facility is separately required, but the sizing step for producing the small coke (A ₂ ) can be omitted, and by crushing There is an advantage that yield reduction can be prevented.

  Moreover, in the said embodiment, in the case where the purchase ratio of the caking coal (L) and the non-slightly caking coal (M) in all the purchased coal is fixed, the high reactivity low intensity | strength coke (A) and low reactivity An example of improving ore reduction efficiency and blast furnace air permeability by adjusting the coal blend of high-strength coke (B) (mixing ratio of non-slightly caking coal (M)) was shown. While maintaining the blast furnace operation at the current level by maintaining the reactivity and strength of the coke at the current level, the coal blend of the strength coke (B) (the blending ratio of non-slightly caking coal (M)) Increase the purchase ratio of non-slightly caking coal (M) in all purchased coals from the current level by increasing the blending ratio of non-slightly caking coal (M) to produce highly reactive low-strength coke (A). It is also possible to reduce coke production costs.

  In order to confirm the effect of the present invention, first, simulation calculation was performed for the case where the purchase ratio of the caking coal (L) and the non-caking caking coal (M) of all purchased coals is fixed.

  The preconditions for this simulation calculation are as follows, based on the average data of blast furnace operation and coke oven operation at typical integrated steelworks in Japan. Of the following numerical values, constant values and reference values that are not displayed are fixed values. The reference value is a value in the case of the conventional technique (comparative example) in which the coke making is not performed. In addition, the amount of change in coke properties and the amount of change in blast furnace operation were set to appropriate values while referring to various literature data, as noted in the following notes 1 to 4.

(Prerequisite)
・ Purchased coal: 80% caking coal, 20% non-caking coal (constant value)
・ Coke production: 395kg / t-pig (reference value)
・ Ratio of coke by particle size:
Normal coke or low-reactivity high-strength coke: Large coke 85%, small coke 10%, fine coke 5%
High-reactivity low-strength coke: small coke 95%, fine coke 5%
・ Coke ash: 12% by mass
・ Pulverized coal ratio: 125kg / t-pig (reference value)
・ Ash content of pulverized coal: 8% by mass
・ Burning rate of pulverized coal in the raceway: 80%
・ Solution loss C amount in blast furnace: 90kg / t-pig
・ Coke properties:
Reference value: DI ¹⁵⁰ ₁₅ : 84.5, CRI: 30.0
Amount of change: Mixing ratio of non-slightly caking coal: +10 mass%, DI ¹⁵⁰ ₁₅ : -1.0 (see note 1 below), DI ¹⁵⁰ ₁₅ : per -1.0, CRI: +5.0 (note below) 2)
-Change in blast furnace operation: DI ¹⁵⁰ _{15 for} large coke: +1.0, large coke ratio: -10 kg / t-pig (see note 3 below), CRI for small coke: per +10, pulverized coal ratio: -4kg / t-pig (see note 4 below)

Note 1: (1) Relationship between charcoal types and DI150 / 15 measured values in Table 1 of “JP 2002-294250 A”, and (2) “Sakawa et al: Flow of Steel Technology, 2nd Series, Volume 12 , Coal and coke, issued on December 20, 2002, Japan Iron and Steel Institute, p.102 ", influence of steam coal (+ 10%) on cold strength DI ¹⁵⁰ ₁₅ (%) in Fig. 4.2.5 Was set with reference to.
Note 2: (3) It was set with reference to the relationship between the actual operation value of coke cold strength DI and ΣCRI in Table 2 of “JP-A-10-36855”.
Note 3: (4) Relationship between coke cold strength (DI 150/50) (%) and fuel ratio (kg / t-pig) in Table 1 of “JP-A-6-108126”, (5) “ DI ³⁰ ₁₅ [%] and coke ratio [kg] in Figures 5 and 84 of Japan Iron and Steel Institute, 3rd Edition, Steel Handbook, Volume II Steelmaking and Steelmaking, published on October 15, 1979, Maruzen, p.259 / T] (6) obtained by converting the relationship between various DI indices in Table 3 of “Journal of Fuel Association, Vol. 58, No. 631 (1979), p. 933”. , DI ¹⁵⁰ ₁₅ [%] and coke ratio [kg / t], and (7) “ISIJ International, Vol. 45 (2005), No. 10, p. 1376” FIG. With reference to the relationship between DI 150-15 (%) and RAR [reducing material ratio] (kg / t) in No. 17, the reduction in the fuel ratio (reducing material ratio) was set by considering the reduction in the total amount of coke ratio.
Note 4: FIG. 8 of (8) “ISIJ International, Vol. 45 (2005), No. 10, p. 1382”. Referring to the relationship between CRI (%) and RAR [reduced material ratio] (kg / t) at JIS-RI = 70% in Fig. 6, the decrease in fuel ratio (reduced material ratio) is a decrease in the total pulverized coal ratio. Set by considering.

(Calculation condition)
[Comparative example] (equivalent to conventional technology)
The blending ratio of the blended coal charged in all the carbonization chambers of the coke oven is set to 80% caking coal and 20% non-slightly caking coal (constant) equal to the ratio of purchased coal. Coke produced in a coke oven (usually coke) is classified into large coke, small coke, and fine coke. Large coke is mixed with the coke layer, and small coke is mixed with ore and loaded into the ore layer. Enter.

[Invention Example 1] (corresponding to the above embodiment)
The blended coal charged to the carbonization chamber for 8.3% of the total coking chamber of the coke oven is a raw material for high-reactivity, low-strength coke, and the blending ratio is less than the ratio of purchased coal. The proportion is 40% caking coal and 60% non-caking coal. The blended coal to be charged into the remaining carbonization chamber is a raw material for low-reactivity and high-strength coke, and the blending ratio is determined by balance calculation from the proportion of purchased coal and the blending ratio of the raw material for high-reactivity and low-strength coke. To do. The high-reactivity low-strength coke produced in the coke oven is classified into small coke and powder coke, while the low-reactivity high-strength coke is classified into large coke, small coke, and powder coke. Bulk coke is mixed with the coke layer, and small coke is mixed with ore and charged into the ore layer.

(Calculation result)
The results of the simulation calculation are shown in Table 1 below together with the above preconditions and calculation conditions.

As shown in Table 1 above, Invention Example 1 has a small coke ratio increased by 28 kg / t-pig (40 → 68 kg / t-pig) as compared with the conventional (comparative example), and accordingly, the reducing material ratio Under certain conditions, the large coke ratio will decrease by 28 kg / t-pig, but DI ¹⁵⁰ _{15 for} large coke will be 0.4 (84.5 → 84.9) higher than the conventional (comparative example). As a result, the large coke ratio is further reduced by 4 kg / t-pig, and the total mass is reduced by 32 kg / t-pig (336 → 304 kg / t-pig).

On the other hand, by adding 33 kg / t-pig of small-grain coke derived from high-reactivity low-strength coke (small-grain high-reactivity low-strength coke) (A ₂ ) to the ore layer, a solution loss C amount of 90 kg / t-pig 29 kg / t-pig (33 × (1-12 / 100) = 29) is replaced from normal coke to highly reactive low strength coke. Therefore, the pulverized coal ratio is reduced by 3 kg / t-pig ((29/90) × (50-30) × 0.4 = 3) compared to the conventional case (comparative example). As a result, the reducing material ratio is reduced by 7 kg / t-pig in total (501 → 494 kg / t-pig), and it can be seen that a significant reduction effect of the hot metal production cost can be obtained.

  In Invention Example 1, the large coke ratio is reduced by 32 kg / t-pig (336 kg / t-pig → 304 kg / t-pig) compared to the conventional (comparative example), so that the function as a spacer is hindered. It seems like. However, the solution loss C amount of large coke is also reduced by 24 kg / t-pig from the conventional (comparative example) (32 → 8 kg / t-pig; equivalent to 27 kg / t-pig decrease in large coke amount) The amount of large coke that remains without being consumed in the solution loss reaction is almost the same as the conventional (comparative example), and hardly affects the function as a spacer.

  Next, while maintaining the blending ratio of the non-slightly caking coal (M) in the low-reactivity high-strength coke (B) as before, the non-slightly-caking coal ( Simulation calculation was performed for the case where the blending ratio of M) was increased.

  The preconditions for this simulation calculation are the same as in Example 1 except that the proportion of purchased coal is not a constant value but a reference value (that is, the proportion of purchased coal can change) as shown below. .

(Prerequisites) [Only differences from the preconditions of Example 1 above are shown]
・ Purchased coal: 80% caking coal, 20% non-caking coal (standard value)

(Calculation condition)
[Invention Example 2] (corresponding to a modification of the above embodiment)
The blended coal charged into the carbonization chamber for 8.3% of the total carbonization chamber of the coke oven is used as a raw material for high-reactivity low-strength coke, and the blending ratio is conventionally (comparative example of Example 1 above, hereinafter, It is simply referred to as “comparative example”). The blending ratio of non-slightly caking coal is increased to 40% caking coal and 60% non-slightly caking coal. The blended coal charged into the remaining carbonization chamber is maintained at the same blending ratio as the conventional (comparative example) as a raw material for the low-reactivity high-strength coke (= normal coke). And like the said invention example 1, while the highly reactive low intensity | strength coke manufactured with the coke oven is classified into a small grain coke and a powdery coke, low reactive high intensity | strength coke (= normal coke) is a large lump coke. The large coke is mixed with the coke layer, and the small coke is mixed with the ore and charged into the ore layer.

(Calculation result)
The results of the simulation calculation are shown in Table 2 below together with the above preconditions and calculation conditions in comparison with the comparative example.

As is clear from Table 2 above, DI ¹⁵⁰ ₁₅ of the large coke is maintained the same as the conventional (comparative example), and therefore, the large coke ratio of the large coke ratio due to the rise of DI ¹⁵⁰ ₁₅ as in the inventive example 1 is increased. A further reduction effect cannot be obtained. However, by adding the same 33 kg / t-pig portion of the small coke derived from the high reactivity low strength coke (small particle high reactivity low strength coke) (A ₂ ) to the ore layer as in Invention Example 1, the pulverized coal ratio Is 3 kg / t-pig lower than the conventional (comparative example). Therefore, although the reduction of the reducing material ratio is less than 7 kg / t-pig of Invention Example 1, a reduction effect of 3 kg / t-pig (501 → 498 kg / t-pig) is obtained.

  In addition to this, as compared with Invention Example 1 and Comparative Example, the purchase ratio of expensive caking coal decreased, and the purchase ratio of inexpensive non-caking coal increased, thereby reducing the production cost of coke. In combination with the reduction of the reducing material ratio, a significant effect of reducing the hot metal production cost can be obtained.

  In Inventive Example 2, the mass loss coke ratio is 28 kg / t-pig (336 kg / t-pig → 308 kg / t-pig) less than the conventional (comparative example), but the solution loss C amount of the large mass coke. Has also been reduced by 24 kg / t-pig (32 → 8 kg / t-pig) compared to the conventional (comparative example) (corresponding to 27 kg / t-pig reduction in the amount of large coke) and is not consumed by the solution loss reaction. The amount of the remaining large coke is almost the same as that of the conventional (comparative example), and it is the same as that of the above-described invention example 1 that does not affect the function as the spacer.

It is a flowchart for demonstrating the hot metal manufacturing process which consists of a coke oven and a blast furnace based on one Embodiment of this invention.

Explanation of symbols

1: coke oven 2: crusher 3,4,5: Sieve 6: blast furnace A: highly reactive low intensity Coke A _2: small highly reactive low strength coke (small coke)
B: Low reactive high strength coke B ₁ : Large mass low reactive high strength coke (large mass coke)
B ₂ : Small grain low-reactivity high strength coke (small grain coke)
C: ore D: mixture F: fine coke L: caking coal M: non-caking coal P, Q: blended coal

Claims (5)

A method for operating a blast furnace in which hot metal is produced using coke produced in a coke oven as a reducing material, comprising the following steps [1] to [5].
[1] Coke production process for producing high-reactivity low-strength coke (A) and low-reactivity high-strength coke (B) in the coke oven [2] Particle size adjustment of the high-reactivity low-strength coke (A) First sizing step of preparing a small-grain high-reactivity low-strength coke (A ₂ ) [3] The low-reactivity high-strength coke (B) is sized to provide a large mass low-reactivity high-strength coke (B ₁ ) And small grain low reactivity high strength coke (B ₂ ) [4] The small grain high reactivity low strength coke (A ₂ ) and the small grain low reactivity high strength coke (B ₂ ) Mixing step to mix in ore (C) to form mixture (D) [5] This mixture (D) and the large mass low-reactivity high-strength coke (B ₁ ) are alternately charged into the blast furnace. The charging process. The reactivity index CRI of the high-reactivity low-strength coke (A) is greater than 30, the difference from the CRI of the low-reactivity high-strength coke (B) is 5 or more, and the low-reactivity high-strength blast furnace method according to claim 1 for the difference between the ^DI _{0.99 15} coke (B) of the drum strength index ^DI _{0.99 15} and the high reactivity low strength coke (a) 0.5 or more. So as to satisfy the following equation 1, blast furnace operation according to claim 1 or 2 for adjusting the charging amount _{W A2 [kg / t-pig} ] of the small highly reactive low strength coke to the blast furnace (A ₂₎ Method.
Formula _{1 W A2 ×% C A /} 100 ≦ C SL + C C -W B2 ×% C B / 100-W PC × (1-% Ash PC / 100) × (1-% BR PC / 100)
Here,% C _A is the C content [% by mass] of the high-reactivity low-strength coke (A), C _SL is the solution loss C amount [kg / t-pig] in the blast furnace, and C _C is in the hot metal C content _{[kg / t-pig],} W B2 is the charging amount of the blast furnace [kg / t-pig], % C B is the low reactivity of the small low-reactive high-strength coke _{(B 2)} C content [% by mass] of high-strength coke (B ₂ ), W _PC is the pulverized coal ratio [kg / t-pig] in the blast furnace,% Ash _PC is the ash content of the pulverized coal [% by mass],% BR _PC Is the combustion rate [%] in the raceway of the pulverized coal. The charging amount W _A2 [kg / t-pig] of the small high-reactivity low-strength coke (A ₂ ) to the blast furnace is adjusted so as to satisfy the following formula 2 instead of the formula 1. The blast furnace operating method described.
Formula _{2 W A2 ×% C A /} 100 ≦ C SL -W B2 ×% C B / 100-W PC × (1-% Ash PC / 100) × (1-% BR PC / 100)   When the use ratio of non-slightly caking coal relative to the total amount of coal used in the coke oven is X mass%, the blended coal (P) in which the blending ratio of the non-slightly caking coal is higher than X mass%, A blended coal (Q) having a blending ratio of non-slightly caking coal lower than X mass% is prepared, and these blended coals (P and Q) are charged into separate carbonization chambers of the coke oven and dry-distilled. The blast furnace operating method according to any one of claims 1 to 4, wherein the high-reactivity low-strength coke (A) and the low-reactivity high-strength coke (B) are separately produced.

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