JPH1036855A - Compounding method for coal to be used in producing coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cost for producing a coke by using a compounding method in which an O/C atomic ratio of each of coal brands to be used is in advance determined and then coal brands are compounded in a way such that the resulting compound has a total of atomic ratios, ΣO/C, satisfying specific formulae showing the relationship between the total of atomic ratios and values of a target cold strength and a target hot strength of a coke product. SOLUTION: In advance, are determined an O/C atomic ratio and coke conversion CRI after carbonization for each of coal brands to be used for compounding. And then coal brands are compounded in a way such that the resulting compound has a total of atomic ratios, ΣO/C, and a total of coke conversions, ΣCRI, satisfying both of formula I representing a target cold strength DI: DI=a×ΣO/C+C1 , and formula II representing a target hot strength SCR: CSR=b×ΔO/C-d×ΣCRI+C2 , wherein a, b, c1 , c2 and d are constants determined by the operation pattern of a coke oven. The compound thus obtained is charged into a coke oven to thereby produce a coke having a target quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for blending coal for producing coke.

[0002]

2. Description of the Related Art A particularly important control item in the production of coke for blast furnaces is strength. While improving the coke strength stabilizes the operation of the blast furnace, it also requires an increase in the proportion of expensive coking coal, so the coke strength (cold strength DI, hot strength CS
It is effective for cost reduction to bring the target value of R) as close as possible to the lower limit value in required quality. In order to lower this target value, it is necessary to reduce the variation in coke quality, and ideally, it is desirable to always keep the blending ratio of each brand of coal constant. However, in actual operations, it is difficult to supply coal, so coke strength is estimated from changes in coal properties when brands are switched.

As an estimation method, for example, there is a method based on a combination of a coalification parameter of a blended coal and a caking parameter. The coalification parameter is an average reflectance (Ro) of vitrinite indicating the maturity of coal. And the caking parameter is the highest fluidity (M
The method represented by F) is generally used. Further, as a new caking property parameter, there is a solidification temperature (Tr) of coal in Japanese Patent Publication No. 2-14398.

[0004]

In recent years, the use of inexpensive non-fine caking coal has been expanded in order to reduce the cost of coke production. Since the maximum fluidity (MF) and the solidification temperature (Tr), which are the caking properties of the prior art, are indexes only for caking coal, the measured values of non-fine caking coal And the effect below zero could not be indexed.

For this reason, it is not possible to accurately estimate the coke strength at the time of blending non-coking coal, but it is necessary to increase the variation in coke quality, to reduce the cold strength DI and the hot strength CSR.
As a result, the use of non-caking coal was restricted, and it could not be used in large quantities.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the accuracy of estimating the quality of coke, to perform proper coal blending even when a large amount of non-coking coal is blended, and to produce coke having a small variation and stable strength. It is assumed that.

[0007]

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and its means 1 is to mix a plurality of brands of coal before charging them into a coke oven. Oxygen carbon atom ratio (O / C) for each
According to the following formula (1), the blending ratio for each coal brand is set so that the total oxygen carbon atom ratio 配合 O / C of the blended coal satisfying the target coke cold strength (DI). DI−a × ΣO / C + C ₁ (1) where a and C ₁ are constants determined from the coke oven operation mode.

Means 2 mixes a plurality of brands of coal and charges them into a coke oven beforehand. The oxygen / carbon atom ratio (O / C) of each coal brand and the reaction rate (CRI) of coke after carbonization are determined in advance. ) Is determined, and the total oxygen carbon atoms of the blended coal satisfying the target coke cold strength (DI) by the following equation (1) and satisfying the target coke hot strength (CSR) by the following equation (2) are obtained. Number ratio {O / C, total reaction rate}
This is a method in which the blend ratio is set for each coal brand so as to obtain CRI. DI−a × ΣO / C + C ₁ (1) CSR = b × ΣO / C + d × ΣCRI + C ₂ (2) where a, b, d and C ₁ , C ₂ are determined from the operation mode of the coke oven. constant

The operation of the present invention will be described below in detail. The present invention considers the difference between caking coal that softens and melts by dry distillation in a coke oven and non-fine caking coal that does not soften and melt as the effect of oxygen-containing groups that are present in large amounts in non-fine caking coal. It was considered in the model shown. The caking coal is CH as shown in FIG.
_3. It contains a large amount of a polymer having about 4 aromatic rings containing H, etc., and after softening and melting by thermal decomposition, solid lump polymerization produces a strong lump coke.

On the other hand, as shown in FIG. 1 (b), the non-sintered coal has two aromatic rings containing oxygen-containing groups such as O, OH and COOH.
It is considered that a small molecule having a low molecular weight forms a strong electrostatic bond by hydrogen bonding to form a polymer. For this reason, it hardly shows softening and melting properties, and when it is carbonized, only a skeleton structure from which volatile components have been separated out is generated, so that weak coke having weak bonding force between particles is generated.

[0011] Then, the existence ratio of oxygen-containing groups for each coal brand was expressed as oxygen carbon atom ratio (O / C), and the relationship with the coke strength after carbonization was investigated. As shown in FIG. In addition, it was confirmed that the cold strength DI and the hot strength CSR continuously decreased as the O / C increased regardless of the type of non-coking coal. From this, by adopting O / C as a parameter of the estimation formula of the cold strength DI and the hot strength CSR, it is possible to accurately estimate the DI and the CSR, and to obtain the target cold strength DI and the hot strength. The CSR could be reduced and a large amount of non-coking coal could be used.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Tables 1 and 2 show the relationship between the compounding results by brand every month in the actual coke oven and the actual cold strength DI and hot strength CSR. Table 1 shows, from the upper left, caking coal and non-coking coal
The oxygen carbon atom ratio (O / C) of each brand, the coke conversion after carbonization (CRI) of each brand, and the blending ratio for each brand are shown.

Table 2 shows the total oxygen carbon atom ratio 酸 素 O / which is added to the upper row by multiplying the O / C of each brand by the blending ratio of each brand.
C and the reaction rate CRI of each brand multiplied by the blending ratio for each brand, and the total reaction rate ΣCRI, which is an additive value, is shown. The lower row shows the estimated cold strength DI according to the present invention and the conventional method, and the actual cold rate, The relationship between the hot strength DI, the estimated hot strength CSR, and the actual hot strength CSR is shown. At this time, the estimated cold strength D
I is calculated as _{a × ΣO / C + C 1} , a at this time is -16
3, C ₁ was between 0.32 × standing time (hr) +92.4. The estimated hot strength CSR is b × {O / C + d ×}
Calculated in CRI + C _2, b at this time -345, d is -
0.51, C ₁ was between 0.4 × standing time (hr) +92.4. When the placement time is constant, C ₁ and C ₂ may be constants.

The blending ratio of coal by brand satisfies the target DI and the target CSR in the equation for estimating DI and CSR.
/ C, ΔCRI. Next, it is pulverized by a pulverizer to 3% or less to 76% and dried to a moisture content of 2%, and then charged into a Nippon Steel S-type two-piece coke oven (width 440 mm x height 6092 mm x length 15800 mm), The carbonization was performed under operating conditions of 125%, a furnace temperature of 1100 ° C., a carbonization time of 17 hours, and a holding time of 2 hours. After carbonization, the coke was cooled with nitrogen, and the cold strength DI, hot strength CSR and reaction rate of the coke were measured.

The cold strength DI of coke is 1500 m in diameter.
10 kg of coke at room temperature is charged into a cylindrical drum having a length of 1500 mm and a length of 1500 mm. After rotating the drum at 150 rpm, the drum is taken out and sieved with a 15 mm sieve. The above is the percentage of coke weight. (JIS K2152)

The coke reaction rate CRI is 20 ± 1.
200 g of coke sized to 1 mm at 1100 ° C.
The reaction was carried out at 100% CO ₂ (5 l / min) for a time, and expressed as a ratio of the weight of the reacted coke to the weight of the coke before the reaction. The coke hot strength CSR is obtained by subjecting the above reacted coke to room temperature 20 rpm × 30 min.
After a mold test (700 × 130φ) is performed, it is taken out, sieved with a 10 mm sieve, and expressed by the ratio of the weight of coke on the sieve to the weight of coke charged.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to Tables 1 and 2. Further, the conventional estimation values in the table are obtained by indexing the measurement results of the reflectance of coal into carbonization parameters and caking parameters.

[0018]

[Table 1]

[0019]

[Table 2]

Formulation Examples 1 in Tables 1 and 2 show a non-sintered coal blending ratio of 4
5.1%, cold strength DI and hot strength C
The difference between the estimated value of SR and the actual value was better than the conventional estimated value. Also, in the case of Formulation Examples 2 to 6, similarly, the non-sintered coal blending ratio is 32.8% to 46.2%.
, The differences between the estimated values and the actual values of the cold strength DI and the hot strength CSR were all better than the conventional estimated values. As can be seen from the blending examples, the present invention was able to significantly reduce the estimation error of the cold strength DI from 0.28% in the conventional method to 0.28% even in the case of blending non-sintered coal. . Furthermore, for CSR, the estimation error was significantly reduced from 2.62% of the conventional method to 1.48%.

[0021]

According to the present invention, when a plurality of coals are blended and charged into a coke oven, it is possible to produce coke having stable and stable cold strength, hot strength and reaction rate with less variation. Since the target strength can be reduced, the use of inexpensive non-coking coal can be increased, and the cost of producing coke can be greatly reduced, and the effect in this field is great.

[Brief description of the drawings]

FIG. 1 (a) is a molecular structure model diagram of caking coal, and FIG. 1 (b) is a molecular structure model diagram of non-fine caking coal

Fig. 2 (a) shows the results of coking coal O / C and coke performance D
A graph showing the relationship between I and (b) is a graph showing the relationship between the ΣO / C of blended coal and the actual CSR of coke

Claims (2)

[Claims] When a plurality of coal brands are blended and charged into a coke oven, an oxygen carbon atom ratio (O / C) for each coal brand is determined in advance, and a target is determined by the following equation (1). A coal blending method for producing coke, characterized in that the blending ratio is determined for each coal brand so that the total oxygen carbon atom ratio of the blended coal satisfying the coke cold strength (DI) ΣO / C. DI−a × ΣO / C + C ₁ (1) where a and C ₁ are constants determined from the coke oven operation mode. 2. When a plurality of brands of coal are blended and charged into a coke oven, the oxygen carbon atom ratio (O / C) and the reaction rate (CRI) of coke after carbonization for each coal brand are determined in advance. The total oxygen carbon atom ratio 合計 O of the blended coal satisfying the target coke cold strength (DI) according to the following equation (1) and satisfying the target coke hot strength (CSR) according to the following equation (2). / C, a blending ratio for each coal brand such that a total reaction rateΣCRI is obtained. DI−a × ΣO / C + C ₁ (1) CSR = b × ΣO / C + d × ΣCRI + C ₂ (2) where a, b, d and C ₁ , C ₂ are determined from the operation mode of the coke oven. constant