JPS61207488A - Method of evaluating quality of raw coal for production of coke for pig iron production - Google Patents

Abstract

PURPOSE:To accurately evaluate the quality of raw coal, by determining the yield of each of coke, coal gas and coal tar obtained in the carbonization of a raw coal and conducting calculation using the obtained data. CONSTITUTION:Determinations are made on the yield of each of coke, coal gas and coal tar obtained in the carbonization of raw coal, the fuel consumption required in the carbonization, the strength at ordinary temperature or strength after reaction with CO2 and the ash content and total sulfur content contained in the formed coke. The quality of the raw coal is evaluated by conducting calculation based on the obtained data using the formula. In the formula, IA is the sum of (yield of each carbonization product x index of availability), IB is the index of total energy required in the carbonization, IC is the index of impurities based on the ash content and total sulfur content and ID is the index of strength determined from the strength at ordinary temperature or the strength after reaction with CO2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for evaluating the quality of coking coal for producing coke for ironmaking, and in particular, the quality of coking coal can be evaluated based solely on the yield and quality of coke obtained by carbonization of coking coal. To evaluate coking coal, we comprehensively consider the yield of auxiliary raw materials such as coking coal, coal gas, and coal tar, the total amount of heat required for carbonization, the strength of coke, and the ash and total sulfur content in coke. It concerns a method for more accurately evaluating quality.

[Conventional technology]

In carrying out the blast furnace pig-making process, coke and slaked lime are used as reducing agents and reduction aids, along with iron sources such as lump iron ore, sintered ore, and pelleted ore. Among them, the amount of coke used is extremely large at 0.4 to 0.5 tons per ton of pig iron, and its quality and price have a significant impact on the production cost of pig iron.

By the way, in the conventional evaluation of ironmaking coke, the factors that affect the reactivity in the blast furnace are the room temperature strength (drum strength specified in JIS K 2151) and the deterioration in the high temperature reducing atmosphere in the blast furnace. In addition to the post-reaction strength (for example, a method of reacting coke size-sized to about 20 mm with CO2 at 1100°C for a certain period of time and calculating it from the rotational strength after that), the ash content, total sulfur content, etc. We take this into consideration when deciding whether or not it is good or bad. When evaluating the quality of the coking coal that is the source of such coke, the yield of coke by carbonization and the The quality of coking coal was evaluated based on the ash content and total sulfur content mixed into finished coke from coking coal.

[Problems to be Solved by the Invention] However, in order to obtain coke by carbonizing coking coal, a large amount of heat for carbonization is required, and the amount of heat varies considerably depending on the quality of the coking coal. Furthermore, coal gas, coal tar, etc., which are by-produced in the carbonization process, have a certain economic value and can be effectively used as by-products, so the yield of these by-products is also a significant factor in the economic value of coking coal. influence

In other words, when evaluating the quality of coking coal for producing coke for ironmaking, the yield and quality of coke, which is a carbonization product of AA, and
Judging only by strength etc. is not necessarily an appropriate method, and it is necessary to comprehensively evaluate it, including the amount of heat required for carbonization, the recovery rate of by-products, etc.

The present invention was based on these findings, and its purpose is to evaluate the quality of coking coal for coke production, not only the quality and yield of coke, which is the main object, but also the amount of heat required for carbonization, and the collection of by-products. The aim is to provide a method that can comprehensively and accurately evaluate the cost, economic value, etc.

[Means for solving problems]

The quality evaluation method of coking coal for coke production according to the present invention is as follows: A: Coke, coal gas, and coal tar obtained by carbonization of coking coal.

B: 1ml of fuel required for carbonization.

C: The room temperature strength or the strength after ω2 reaction of the coke produced, and D = the ash content and total sulfur content in the coke produced, and based on these values, the quality of coking coal is evaluated by the following CI) formula. It has the following.

Total evaluation index =, IA-IB-1c4-ID, -----
--...CI) However, IA: (Yield of each carbonization product)
Sum of X (utility index) IB: Total energy required for carbonization IC: Impurity index based on ash content and total sulfur content in the coke produced ■D = Strength determined from the room temperature strength of the coke produced or ■2 strength after reaction Index [effect] In the present invention, as described above, (yield of each carbonization product) x (
The total energy index (IB) required for carbonization, the impurity index (1 (1)) based on the ash content and total sulfur content of the coke produced, and the room temperature of the coke produced. By incorporating all the strength indices (ID) determined from the strength or the strength after CO2 reaction as evaluation elements of coking coal, and simply adding them with the above IA and ID as positive elements and 1B and Ic as negative elements, the CI ) The total evaluation index of coking coal is determined as shown in the formula, and the quality of coking coal is evaluated based on this index.

The above lA is calculated by multiplying the yield of all products obtained by carbonization of coking coal (main product coke and by-products such as coal gas and coal tar) by the utility index of each product. This is a positive element obtained by combining the following. In other words, when producing coke by carbonization of coking coal,
At the same time, by-products such as those mentioned above can be obtained which have economic value and are also profitable as by-products. Therefore, in the present invention, the yield of not only coke but also other by-products is determined, and the yields are multiplied by the usefulness index (an index indicating the degree of profit obtained by commercialization) of each product and added. This makes it possible to comprehensively evaluate the benefits brought about by carbonization products.The yield of each carbonization product may also be determined by taking a small sample from coking coal and actually measuring it through a carbonization test. Alternatively, by utilizing the method for predicting the yield of carbonized distillation products previously proposed by the present applicant (Japanese Patent Application Laid-Open No. 145283/1983), the volatile content value and elements of the coking coal are applied to the regression equation obtained from a large amount of experimental data. It can also be obtained by substituting analytical values.In addition, the usefulness index of each carbonization product represents the commercial value of the 5-cough product, and the simplest and appropriate standard is the value of the product as a product. Average unit price.

Next, the above I corresponds to the thermal energy required for carbonization, and since it is the total required energy supplied from the outside for carbonization, it is a negative element in terms of its position in the total evaluation index. This energy index may be determined experimentally based on the thermal energy supplied in the carbonization experiment when determining the IA experimentally, or may be determined experimentally based on the "coke manufacturing method" proposed earlier by the present applicant ( JP-A-59-179582)
It can also be calculated by the method disclosed in .

In other words, the energy required for carbonization is [the amount of heat (obvious) required to raise the temperature of coking coal from room temperature to a warm temperature at which each carbonization product is produced, and the fluctuating heat required to produce carbonization products from coking coal.
It (heat of reaction), that is, the required heat for carbonization M (He)) [Compensates for the amount of heat carried away by the endothermic reaction between water vapor and produced coke in the waste generated as a result of carbonization due to water gas production. The above ()IG) can be interpreted as the sum of the heat ii1 (AC)), or the hydrogen to carbon ratio (k) obtained from the volatile matter value (VM) and elemental analysis value of coking coal
4/C) can be obtained almost exactly by substituting it into the regression equation of 'F', and )1c (K41Jc9)=a −VM4−b −(1
4/C) fa (2.b, α is a regression coefficient and a regression constant, and indicates a constant value when certain operating conditions, such as carbonization temperature or coke curing time after completion of carbonization, are constant. ) Furthermore, (AC) can be almost accurately determined by substituting the oxygen-to-carbon ratio (0/C) obtained from the elemental analysis value of raw coal into the regression equation below.

AC (KcaL/&9) = c - (0/C) + β (where C1β is a regression coefficient and a regression constant, and certain operating conditions such as carbonization temperature, coke curing time after carbonization, etc. are constant) In other words, by combining HC and AC obtained by the above formula, the effective amount of heat required for carbonization can be calculated, and the IB value can be determined based on the calculated value. .

In addition, lc in the CI) formula is based on the fact that the ash content and total sulfur content in the coke increase the cost of deashing and desulfurization after blast furnace ironmaking, and considers these factors as an impurity index that is a negative element. This index calculates the relationship between the ash content and total sulfur content in coke and the statistical performance of deashing and desulfurization costs after blast furnace operation, and converts this into ash content and total sulfur content in coking coal. required by.

Furthermore, the ID of formula CI) is incorporated into the total evaluation index considering that coke strength has a considerable influence on blast furnace operability, and is calculated based on the room temperature strength or CO□ reaction reactivity intensification amount,
By statistically understanding the relationship with the amount of change in blast furnace operating efficiency commensurate with this based on the past experience of blast furnace operation, and converting the actually obtained room temperature strength or strength after CO2 reaction into blast furnace operability. Desired. During blast furnace operation, it has been confirmed that the higher the strength of coke, especially after the CO2 reaction, the less pulverization occurs, which has a positive effect on blast furnace operability. It is desirable to adopt strength.

By calculating LA, 18% Ic, and ID using the method described above, and substituting them into the above CI formula with lA and ID as positive elements and IB and lc as negative elements, and adding them, the You can evaluate practical quality.

FIG. 1 is a flowchart showing an example of such calculation of the total evaluation index, and the IA obtained from FIG.

(2) By substituting B, IC, and ID into the above-mentioned formula (CI), the overall evaluation side index of coking coal is calculated. The abbreviations and analysis methods in FIG. 1 are as follows.

C, Hlo: Elemental analysis value (%) of carbon, hydrogen, and oxygen in coking coal (JIS M 8813) M: Volatile content value (%) in coking coal (JISMASH: Ash content (%) in coking coal
JIS M 8801) TS: Total sulfur content in coking coal (%
) (JISM [Example] Coking coals A and B having the properties shown in Table 1 were used and their quality was evaluated.

Looking at the analysis results in Table 1, it appears that coking coal A is of good quality compared to coking coal B, as it has less volatile matter and ash, contains a lot of C, and has a higher coking strength. However, since the yield of each product during carbonization in a coke oven is unknown,
It is not possible to make a comprehensive and consistent evaluation that takes into account the yield of by-products.

When the quality of coking coal A%B is evaluated by the method of the present invention based on the analytical values shown in Table 1, the results are as follows.

First, based on the measured values in Table 1, the yield of the carbonized product and the amount of heat required for carbonization were determined using the following formula, and the values shown in Table 2 were obtained. Table 2 also shows the unit price of each product as a usefulness index for each carbonization product.

Yield calculation formula> :) -ys(%)=-0.78VM+-98.40
-C' Coal gas (Ntd/T) (3,11VME +-227)X t60.38VM
1! , -29,35(0) +-38001 (however, 4
800 Kad/N [as] Coulter 7k (%l=0
．． 38VME 3.17 <Calculation of energy required for carbonization> (KCA/T) 22.8 VM-1550()i/C) +-320(
0/C) +-810 However, C= 0.376 e O
°176 (0) VME=VM l 1.12 (0)
+-0,051 Based on the calculated values in Table 2 and the respective standard unit prices, each index given to the overall evaluation of coking coal is determined as shown in Table 3.

However, the disadvantages of open-cut desulfurization and blast furnace deashing were calculated using the following formula from the analytical values shown in Table 1 and the statistical average values required for desulfurization and deashing.

Disadvantages of desulfurization - Total sulfur content (%) in coking coal Comprehensive comparison of the quality of coking coal A and H from the results of Table 3 shows that coking coal A is superior to coking coal B by 1200 yen/T.

〔Effect of the invention〕

The present invention is configured as described above, and it is possible to improve not only the yield, ash content, and total sulfur content of coke obtained by carbonization, but also the yield and usefulness of other products obtained by carbonization.
This method comprehensively evaluates the quality of coking coal by taking into account the thermal energy required for carbonization, the strength of the coke produced, etc., so it is not simply concerned with the yield and quality of coke.
It is possible to more accurately evaluate the real value of coking coal, including other positive and negative factors.

[Brief explanation of drawings]

FIG. 1 is a schematic flow diagram illustrating a quality evaluation method according to the present invention.

Claims (1)

[Claims] (1) A: Each yield of coke, coal gas, and coal tar obtained by carbonization of coking coal, B: Fuel consumption required for carbonization, C: Room temperature strength of produced coke or strength after CO_2 reaction,
and D: A method for evaluating the quality of coking coal for producing coke for iron making, which comprises determining the ash content and total sulfur content in the produced coke, and evaluating the quality of the coking coal using the following formula based on these values. Total evaluation index = I ＿A− I ＿B− I ＿C− I ＿DHowever
I _A: Total sum of (yield x usefulness index of each carbonization product) I _B: Total energy required for carbonization I _C: Impurity index based on ash content and total sulfur content in the coke produced I _D: Room temperature of the coke produced Strength index determined from strength or strength after CO_2 reaction