JP2001172643A - Method for estimating strength of coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for estimating the strength of coke in good accuracy. SOLUTION: This method for producing the coke by calcining a coal blend obtained from various kinds of coals, characterized by adopting the strengths of single coals after the coke reaction and their yields as parameters for estimating the coke strength, considering the overlapping of the flow property of the coal blend with the flow properties of the single coals and further a parameter which is the index of the alkali component content of the coal blend, estimating the strength of the coke after the coke reaction, and controlling the blending of the coals on the basis of the estimation result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for estimating the strength of coke after coke reaction (hereinafter referred to as CSR), a method for preparing a blended coal and a method for producing coke based on the method.

[0002]

2. Description of the Related Art As coke quality, it is required that powdering due to a reaction in a blast furnace is small, so that a CSR exceeding a predetermined value is required.

[0003] CSR means a numerical value in which the amount that does not powder when a coke is reacted for a certain period of time under a condition described below and then subjected to an I-type drum test at room temperature is expressed as weight%.

"CSR measurement conditions" Sample particle size: 20 ± 1 mm Sample weight: 200 g / time Gas composition: CO ₂ (100%) Gas flow rate: 5 Nl / min Reaction temperature: 1100 ° C. Reaction time: 120 minutes Strength: I-type drum After 600 rotations (20 rpm × 3
0 min) wt% on 10mm sieve

[0005] When changing the blending of coal or changing the target value of CSR, it is necessary to predict the CSR of coke in advance. For this reason, various estimation methods have been conventionally proposed.

[0006]

However, depending on the blending of coal, the estimated value and the actually measured value may be quite different from each other, and the accuracy of the estimation is still not sufficient.

The present applicant has developed a method for estimating CSR (Japanese Patent Publication No. 1-55313). In this method, since the CSR of the blended high-reflectivity coal greatly contributes to the CSR of the blended coal, the reflectance of the coal is divided by 1.1.
The intensity estimation formula is constructed by setting one or more as high-reflectance coal and setting less than 1.1 as low-reflectivity coal. However, even if the reflectance of coal is the same brand, it varies depending on the receiving lot (ship).

An object of the present invention is to provide a technique for accurately estimating the strength of coke in order to solve the above-mentioned problems in the prior art.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have developed the CSR of each raw coal constituting the blended coal.
Of the coking coal and the CSR of the coking coal, the results showed that, among the coking coals constituting the coking coal, the contribution of coking coal with a high coke yield (ratio of the weight of coke obtained by firing to the weight of coal before firing) Was found to be large, and the present invention was completed.

That is, according to the present invention, when coal blends obtained by blending various kinds of raw coals are calcined to produce coke, they are determined by a statistical method using the following parameters (a) to (d). Provided is a method for estimating coke strength (hereinafter, also referred to as "the present invention estimation method"), which includes estimating the CSR of blended coke obtained from blended coal using an estimation formula.

(A) The coke strength (CSRi) of the simple coke obtained by firing each coking coal and the coke ratio of each coking coal which is the ratio of the weight of coke obtained by firing to the weight of coal before firing. Coke CSR (HCSR) calculated from the following formula (1) from the fraction (Bi) and the blending ratio (Xi) of each raw coal,

(5) HCSR = (1 / N) ΣCSRi × Bi × Xi (1) (in the formula (1), N = ΣXi) (b) Index indicating the fluidity of the blended coal, ( c) an index indicating the overlap of the fluidity of each coking coal, and (d) an index indicating the amount of the alkali component of the blended coke.

The index indicating the fluidity of the blended coal is preferably a weight of the blended coal calculated by the following formula (2) from the fluidity (MFi) of each of the raw coals and the blending ratio (Xi) of each of the raw coals. Mean fluidity (MF).

MF = (1 / N) ΣXiMFi (2) (in equation (2), N = ΣXi)

An index indicating the overlap of the fluidity of each coking coal is as follows:
Preferably, it is a variance (VRo) of the reflectance (Roi) of each raw coal, calculated by the following equation (3).

VRo = (1 / N) ΣXi (Roi−Rox) ² (3) (where Rox = (1 / N) ΣXiRoi Rox: weighted average reflectance N = ΣXi )

The index indicating the amount of alkali component of the blended coke is preferably the amount of alkali component (A) calculated by the following formulas (4) to (6).

A = (1 / N) ΣXiAi (4) Ai = Ci × Ei (5) Ci = Di / Bi (6) (where Ci: ash content of plain coke i) (%) Ei: A value (molar ratio) that reflects the amount of alkali component obtained by composition analysis of ash of raw coal i. Di: Ash content of raw coal i (%) N = ΣXi)

[0015] Ei is preferably, [(Ca0 + Mg0 + Fe 2 0 3 + Na
_{2 O + K 2 0) /} (Si0 2 + Al 2 O 3)] is i.

The statistical method is preferably a multiple regression method.

Further, the present invention is a method for preparing a blended coal for producing coke having a predetermined strength, which comprises blending various kinds of raw coals.
Provided is a preparation method characterized by calculating a blending ratio of raw coal for obtaining coke having a predetermined strength, and blending the raw coal with the calculated blending ratio.

Further, the present invention provides a method for producing coke having a predetermined strength, comprising calcining the blended charcoal prepared by the above-mentioned preparation method.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Coking coal used in the present invention is a non-coking coal usually used in the production of coke for iron making.
Fine caking coal, weak caking coal, strong caking coal may be used. These various types are blended and fired to produce coke. The blending conditions (blending method) and firing conditions (type of firing furnace, firing temperature, firing time) may be those usually used for the production of coke for steelmaking.

The estimation method of the present invention is based on an estimation equation obtained by a statistical method using the following parameters (a) to (d):
It is characterized by estimating the CSR of blended coke obtained from blended coal.

(A) The coke reaction strength (CSRi) of plain coke obtained by calcining each coking coal and the coke ratio of the coke obtained by coking, which is the ratio of the coke weight obtained by calcining to the coal weight before calcining. Coke CSR (HCSR) calculated from the following formula (1) from the fraction (Bi) and the blending ratio (Xi) of each raw coal,

(9) HCSR = (1 / N) × CSRi × Bi × Xi (1) (in the formula (1), N = ΣXi) (b) An index indicating the fluidity of the blended coal, ( c) an index indicating the overlap of the fluidity of each coking coal, and (d) an index indicating the amount of the alkali component of the blended coke.

Hereinafter, each parameter will be described. In addition, each coking coal and the coke obtained by sintering it alone are referred to as “simple coal” and “simple coke”, respectively.
Also called.

The HCSR is calculated by the above equation (1). The coke reaction intensity (CSRi) of plain coke is
It can be measured by the method described in the section of the prior art. Plain coke is obtained by calcining plain coal under the conditions of calcining blended charcoal, but this calcining does not necessarily have to be performed in a calciner actually used for the production of coke.
It may be performed in a test furnace that has been found to give equivalent results for CSR. The coke yield (Bi) is the ratio of the weight of coke obtained by firing under the conditions of firing the blended coal to the weight of coal before firing. However, it is not always necessary to actually measure these weights, and it is necessary to use a laboratory. Or the empirical formula of the actual furnace. As an empirical formula of the actual furnace, the amount of coal before calcining and the amount of coke after calcining are measured in the actual furnace, and the yield (B) calculated by the formula: coke amount / coal amount × 100 (%) Relational expression obtained from coal properties such as volatile matter (VM) and firing conditions: B = f (VM,
Other parameters). An estimated yield obtained by inputting the properties of the test coal and the like can be used for this. The mixing ratio (Xi) of each raw coal is based on weight.

The index indicating the fluidity of the blended coal may be obtained by measuring the blended coal itself, or may be calculated from the index indicating the fluidity of each raw coal.
It is preferable to use an index calculated from an index indicating the fluidity of each raw coal, because it is possible to omit the actual production of the blended coal. The index indicating the fluidity of the blended coal is preferably a weighted average fluidity of the blended coal calculated from the fluidity (MFi) of each coking coal and the blending ratio (Xi) of each coking coal by the following formula (2). (MF).

MF = (1 / N) ΣXiMFi (2) (in the equation (2), N = ΣXi)

The index indicating the fluidity is not particularly limited, but usually the highest fluidity measured according to JIS M 8801 is used.

An index indicating the overlap of the fluidity of each coking coal is:
It is not particularly limited as long as it reflects the similarity of the fluidity of the plain coal constituting the blended coal. Preferably,
The reflectance (R) of each coking coal calculated by the following equation (3)
oi) and the variance (VRo) calculated from the mixing ratio (Xi).

VRo = (1 / N) ΣXi (Roi−Rox) ² (3) (where Rox = (1 / N) ΣXiRoi Rox: weighted average reflectance N = ΣXi )

The reflectance is, for example, JIS M 8816
Is the average maximum reflectance measured according to

The index indicating the alkali component amount of the blended coke may be obtained by measuring the blended coke itself, or may be calculated from the indexes of plain coal and plain coke. . It is preferable to use the index calculated from the index of the plain coal and the plain coke, since the actual production of the blended coal can be omitted. The index indicating the alkali component amount of the blended coke is preferably the content ratio of the alkaline component in the ash of the blended coke, and more preferably the alkali component amount (A) calculated by the following formulas (4) to (6). .

A = (1 / N) ΣXiAi (4) Ai = Ci × Ei (5) Ci = Di / Bi (6) (where Ci: ash content of plain coke i) (%) Ei: A value (molar ratio) that reflects the amount of alkali component obtained by composition analysis of ash of raw coal i. Di: Ash content of raw coal i (%) N = ΣXi)

The ash content is determined, for example, according to JIS M 8812.
Is the ash content determined according to The ash composition analysis of the raw coal can be performed, for example, by preparing a ash sample in accordance with JIS M 8812 and subjecting the prepared sample to X-ray fluorescence analysis. From this result, for example, (Ca0 + M
_{g0 + Fe 2 0 3 + Na} 2 O + K 2 0) / ( can be obtained Si0 ₂ + Al ₂ value reflecting the alkaline component amount, such as O ₃₎ (molar ratio). Here, each chemical formula shows the content of the substance represented by the chemical formula on a molar basis.

Based on each of these parameters, it is possible to construct an estimation formula using a measured value of coke strength as a dependent variable by using a statistical method. For example, an estimation formula using the above preferable parameters can be represented by the following formula. CSR of compounded coke = f (HCSR, MF, VRo,
A)

The statistical method is not particularly limited, but examples include a multiple regression method.

The method for preparing a blended coal for producing coke according to the present invention is a method for preparing a blended coal for producing coke having a predetermined strength, which comprises blending various types of raw coal. Based on the estimation method, the blending ratio of the raw coal for obtaining coke having a predetermined strength is calculated, and the raw coal is blended at the calculated blending ratio.

The predetermined strength of coke includes the strength required for coke for iron making. Such strength is determined according to the conditions of iron making and the like.
83% cold strength (JIS K 2151 drum strength)
And the strength after the coke reaction is 55% or more.

The method for producing coke having a predetermined strength according to the present invention is characterized in that the coal blend prepared by the above-mentioned preparation method is calcined.

Although the present invention is not limited to any theory, HCSR is adopted as a parameter for estimating CSR, and furthermore, an index indicating the fluidity of blended coal, the overlap of fluidity of each coking coal, The reason why the estimation accuracy is improved by combining with the index indicating the amount of the alkaline component of the mixed coke and the index indicating the amount of the alkaline component of the mixed coke is estimated as follows.

As a result of examining the relationship between the plain CSR of each coal constituting the blended coal and the CSR of the blended coke, the contribution of the high-reflectance coal to the blended coke is large. Was found to be a large proportion of the mixed coke. That is, it was found that the higher the reflectance of coal, the higher the yield, and consequently the greater the contribution to the blended coke. Therefore, in designing the CSR of blended coke, the coke yield obtained by using the CSR obtained in a test furnace, etc. of the plain coal constituting the blended coal and the formula obtained in the laboratory, etc. It is considered that the approximate blended coke CSR (HCSR) is determined from the formula and the blending ratio of the plain coal.

Further, in the CSR of blended coke, since the flow ranges of the plain coals constituting the blended coal are different, it is necessary to reflect the overlapping of the flows in addition to the blended coal fluidity in the estimation formula. it is conceivable that. In addition, plain charcoal is a natural coal as a result of the effects of its own alkaline components.
Although R is obtained, the blended coal is also affected by the alkali component of the other blended coal, so that it is considered that reflecting the alkali component as blended coke in the estimation formula leads to an improvement in the estimation formula accuracy.

From the above, the blended coke CSR is calculated by multiplying the plain CSR by the coke yield and the blended ratio of the plain coal as the ratio of the plain coal to the blended coke, and in addition to this, It is presumed that the accuracy of the estimation formula can be improved by treating the properties and the overlap of the flow of each plain coal and the alkali component present in the coal as parameters.

[0039]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Various raw coals having the properties shown in Table 1 were blended at the blending ratios shown in Table 2. The obtained coal blend was fired under the following coal firing conditions, and the CSR was measured. Measured CS
R is shown in Table 2.

"Coal firing conditions" Coal particle size Approximately 83% (-3mm) Coal moisture 9wt% Firing furnace Can firing electric furnace Charging amount 15kg Charging bulk density 0.8kg / l Drying temperature 900 ° C Drying time 8 hours

The properties of the coal shown in Table 1 were measured by the following methods.

Ash content (Ash) Measured according to JIS M8812.

Volatile content (VM) Measured according to JIS M8812.

Coke yield (B) The amount of coal charged during the firing of the coal and the amount of coke after the firing were measured and determined as the value of the amount of coke / the amount of charged coal × 100%.

Maximum average reflectance (Ro) Measured according to JIS M8816.

Maximum flow rate (MF) Measured according to JIS M8801.

Composition analysis value (E) Ash was prepared in accordance with JIS M 8812 and quantified by a fluorescent X-ray method. The _{results, (Ca0 + Mg0 + Fe 2} 0 3 + Na 2 O +
_{K 2 0) / (Si0 2} + Al 2 O 3) ( molar ratio) was calculated.

Further, each coal was fired under the above-mentioned firing conditions of the coal, and the CSR was measured.

On the other hand, from the above results, HCSR, MF,
Regression coefficients and constants of each independent factor determined by multiple regression using VRo and A as parameters were as follows.

HCSR: 1.326 MF: 11.129 VRo: -5.996 A: -1.697 Constant: -27.22

Table 2 shows the CSR calculated from this estimation formula (Example). Furthermore, for comparison,
Table 2 also shows the estimation results by the method proposed in No. 13 (Comparative Example).

It can be seen that the estimation method of the present invention has obtained a value close to the actually measured value.

[0054]

[Table 1] Table 1 Properties of test coal ────────────────────────────────── Brand Ash VM B Ro MF E CSR ａa 9.63 19.23 82.95 1.57 1.74 0.033 72.5 b 10.58 20.93 81.47 1.35 2.44 0.053 61.3 c 8.14 25.19 77.47 1.12 2.75 0.053 67.6 d 9.80 20.40 81.93 1.43 0.95 0.070 72.6 e 7.52 25.24 77.70 1.15 1.88 0.183 56.6 f 8.50 29.30 74.14 0.99 1.76 0.112 30.9 g 5.95 34.70 69.42 0.93 4.45 0.098 50.0 8.90 i 6.37 37.01 67.40 0.85 4.78 0.043 18.2 j 7.81 40.89 64.00 0.75 3.27 0.187 49.4 ──────────────────────────────────

[0055]

[Table 2] Table 2 Mixing ratio and measured and estimated CSR ─────────────────────────────── Brand Mixing ratio (% ) Formula 1 Formula 2 Formula 3 Formula 4 Formula 4 a 24 24 3 3.5 b 12 12 3 3.5 c 9 9 27 31.5 d 3 3 15 17.5 e 12 12 12 14 f 12 12 12 9 g 18 8 18 0 h 8 8 2 15 i 0 0 8 0 j 2 12 0 6 ────────── ───────────────────── CSR (compound) (%) Actual value 54.8 53.8 55.4 51.9 Example calculated value 55.1 53.4 55.8 52.6 Difference from actual measured value -0.3 +0.4 -0.4 -0.7 Comparative example calculated value 54.0 51.5 56.9 55.0 Difference from actual measured value +0.8 +2.3 -1.5 -3.1 ─────────────────────── ────────

[0056]

According to the estimation method of the present invention, since the CSR of coke can be estimated with high accuracy, it is easy to determine the blending ratio in accordance with the blending change of various coking coals.
INDUSTRIAL APPLICABILITY The preparation method of the present invention can control the CSR of product coke accurately at the time of blending of raw coal, and is therefore extremely useful as a blended coal preparation method for producing coke. By using the blended charcoal thus prepared, coke having a predetermined strength can be stably produced.

Claims (8)

[Claims] Claims 1. When baking coal blended by blending various types of raw coal to produce coke, the following (a) to
By the estimation formula obtained by the statistical method using the parameter (d), the CSR of the blended coke obtained from the blended coal is calculated.
And estimating the coke strength. (a) The coke yield (Bi) of each coking coal, which is the ratio of the coke reaction strength (CSRi) of the plain coke obtained by firing each coking coal to the weight of the coke obtained by firing with respect to the coal weight before firing. ) And the blending ratio (Xi) of each coking coal, and the coke CSR (HC
HCSR = (1 / N) ΣCSRi × Bi × Xi (1) (in the formula (1), N = ΣXi) (b) The fluidity of the blended coal is shown. An index, (c) an index indicating the overlap of the fluidity of each coking coal, and (d) an index indicating the amount of alkali component of the blended coke. 2. A weighted average of blended coal calculated from the following formula (2) based on fluidity (MFi) of each raw coal and blending ratio (Xi) of each raw coal is used as an index indicating the fluidity of blended coal. The estimation method according to claim 1, which is liquidity (MF). MF = (1 / N) ΣXiMFi (2) (in equation (2), N = ΣXi) 3. The variance (VRo) of the reflectance (Roi) of each coking coal calculated by the following equation (3), wherein the index indicating the fluidity overlap of each coking coal is: Estimation method. VRo = (1 / N) ΣXi (Roi−Rox) ² (3) (where Rox = (1 / N) ΣXiRoi Rox: weighted average reflectance N = ΣXi ) 4. An alkali component amount (A) calculated from the following formulas (4) to (6), wherein the index indicating the amount of the alkali component of the blended coke obtained from the blended coal is: The estimation method described in the section. A = (1 / N) ΣXiAi (4) Ai = Ci × Ei (5) Ci = Di / Bi (6) (where Ci: ash content of plain coke i) (%) Ei: A value (molar ratio) that reflects the amount of alkali component obtained by composition analysis of ash of raw coal i. Di: Ash content of raw coal i (%) N = ΣXi) 5. Ei is, [(Ca0 + Mg0 + Fe 2 0 3 + Na 2 O + K 2 0) / (S
5. The estimation method according to claim 4, wherein i0 ₂ + Al ₂ O ₃ )] i. 6. The method according to claim 1, wherein the statistical method is a multiple regression method.
6. The estimation method according to any one of 5. 7. A method comprising blending multiple types of coking coal.
A method of preparing a coal blend for producing coke having a predetermined strength, the blending of raw coal for obtaining a coke having a predetermined strength based on the estimation method according to any one of claims 1 to 6. A preparation method, comprising calculating a ratio, and blending raw coal at the calculated blending ratio. 8. A method for producing coke having a predetermined strength, comprising calcining the blended coal prepared by the method according to claim 7.