JPS6340833B2 - - Google Patents

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, it is not possible to evaluate the quality of coking coal only by the yield and quality of coke obtained by carbonization of coking coal. The quality of coking coal can be determined more accurately by comprehensively considering the yield of auxiliary raw materials such as 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 the method of evaluation. [Prior art] In carrying out the blast furnace pigmaking process, large amounts of coke and slaked lime are used as reducing agents and reduction aids, along with iron sources such as lump iron ore, sintered ore, and pellet 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 high temperature reducing atmosphere in the blast furnace. In addition to post-reaction strength that takes into account deterioration in coke (for example, a method of reacting coke size-sized to about 20 mm with CO ₂ at 1100℃ for a certain period of time and calculating it from the subsequent rotational strength), the ash content and total sulfur in coke We judge whether it is good or bad by taking into account factors such as When evaluating the quality of coking coal that is the source of such coke, the yield of coke by carbonization, and the yield of coke of what quality can be obtained. 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, obtaining coke by carbonizing coking coal requires a large amount of heat for carbonization, and the amount of heat varies considerably depending on the quality of the coking coal. Moreover, 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 small compared to the economic value of coking coal. influence.
In other words, when evaluating the quality of coking coal for producing coke for ironmaking, it is not necessarily an appropriate method to judge only by the yield, quality, strength, etc. of coke, which is a product of carbonization. It is necessary to comprehensively evaluate the amount of heat required, the recovery rate of by-products, etc. The present invention was made based on such knowledge, and its purpose is to evaluate 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 the problem] The quality evaluation method of coking coal for coke production according to the present invention is as follows: A: Yields of coke, coal gas, and coal tar obtained by carbonization of coking coal; B: Yields of coke, coal gas, and coal tar obtained by carbonization of coking coal; Required fuel consumption, C: ash content and total sulfur content of the coke produced, and D: strength at room temperature or strength after CO ₂ reaction in the coke produced, and based on these values, calculate coking coal using the following formula []. The gist of this is to evaluate the quality of. Total evaluation index = I _A − I _B − I _C + I _D … [] However, I _A : Total sum of (yield of each carbonization product) × (utility index) I _B : Total required energy index for carbonization I _C : Impurity index I _D based on the ash content and total sulfur content in the produced coke: Strength index determined from the room temperature strength of the produced coke or the strength after CO ₂ reaction [Function] In the present invention, as described above (the yield) x (utility index of each carbonization product) (I _A ),
The total energy required for carbonization (I _B ), the impurity index (I _C ) based on the ash content and total sulfur content in the coke produced, and the room temperature strength of the coke produced or CO ₂
All of the strength indexes (I _D ) determined from the post-reaction strength are incorporated as evaluation factors for coking coal, and the above I _A and
By simply adding I _D as a positive element and I _B and I _C as negative elements, the total evaluation index of coking coal is obtained as shown in the formula [] above, and the quality of coking coal is determined based on this index. It evaluates superiority and inferiority. The above _IA calculates the utility index of each product by the yield of all products obtained by carbonization of coking coal (coke, the main product, and by-products such as coal gas and coal tar). This is the positive factor obtained by multiplying and adding them together. That is, when coke is produced by carbonization of coking coal, the above-mentioned by-products that have economic value can be obtained at the same time.
These also provide benefits as by-products. Therefore, in the present invention, the yield of not only coke but also other by-products is determined, and the yield is multiplied by the utility index (an index indicating the degree of profit obtained by commercializing the product) of each product and added. , making it possible to comprehensively evaluate the benefits provided by carbonization products. The yield of each carbonization product may be determined by taking a small sample from raw coal and conducting a carbonization test, or the yield of each carbonization product as previously proposed by the applicant may be determined. It can also be determined by utilizing the yield prediction method (Japanese Patent Laid-Open No. 145283/1983) and substituting the volatile content value and elemental analysis value of the coking coal into a regression equation determined from a large amount of experimental data. Furthermore, the usefulness index of each carbonized product represents the commercial value of the product, and the simplest and most appropriate standard is the average unit price as a product. Next, the above I _B 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 _IA is experimentally determined, or may be determined experimentally based on the "coke manufacturing method" previously proposed by the applicant. It can also be calculated by a method such as that disclosed in Japanese Patent Application Laid-Open No. 59-179582. In other words, the energy required for carbonization is [the amount of heat (sensible heat) required to raise the temperature of coking coal from room temperature to the temperature at which each carbonization product is produced, and the fluctuating heat amount (4 reaction heats) when carbonization products are produced from coking coal] , that is, the amount of heat required for carbonization (HC)] and [in the various gases generated as a result of carbonization,
It can be interpreted as the sum of the amount of heat (AC)] used to compensate for the amount of heat carried away in the endothermic reaction between water vapor and produced coke due to the production of water gas, but the above (HC) is the volatile content value (VM ) and the hydrogen-to-carbon ratio (H/C) obtained from the elemental analysis value can be almost accurately determined by substituting it into the multiple regression equation below, HC (Kcal/Kg) = a・VM+b・( H/C)+α (However, a, b, and α are regression coefficients and regression constants, and they show constant values under certain operating conditions, such as when the carbonization temperature and coke curing time after carbonization are constant. ) Furthermore, (AC) can be almost accurately determined by substituting the oxygen carbon ratio (O/C) obtained from the elemental analysis value of raw coal into the regression equation below.
AC (Kcal/Kg) = c・(O/C)+β (where c and β are regression coefficients and regression constants,
If certain operating conditions such as carbonization temperature and coke curing time after completion of carbonization are constant, the value will be constant.) In other words, by combining HC and AC obtained by the above formula, the effective carbonization The required amount of heat can be determined by calculation, and based on the calculated value, the above I _B
You can know the value. In addition, I _C in the [equation] is based on the fact that the ash content and total sulfur content contained in coke increase the deashing cost and desulfurization cost after blast furnace ironmaking, and considers these 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 costs required for deashing and desulfurization after blast furnace operation, and calculates the relationship between the ash content and total sulfur content in coking coal. It can be found by converting. Furthermore, I _D in the formula [] is incorporated into the overall evaluation index considering that coke strength has a considerable influence on blast furnace operability, and is calculated based on the coke strength obtained from the preliminary carbonization experiment. Room temperature strength or _CO2
The relationship between the amount of change in strength after reaction and the corresponding amount of change in blast furnace operating efficiency is statistically understood based on the actual results of blast furnace operation, and the room temperature strength or strength after CO ₂ reaction of the coke actually obtained is calculated. It is obtained by converting the value into blast furnace operability. During blast furnace operation, it has been confirmed that the higher the strength of coke, especially after the CO ₂ reaction, the less pulverization it will have, which will have a positive effect on blast furnace operability.In this sense, _{CO 2} It is desirable to adopt the strength after reaction. Determine I _A , I _B , I _C and _ID respectively using the method described above,
By substituting and adding I _A and I _D as positive elements and I _B and I _C as negative elements to the above formula, it is possible to evaluate the quality of coking coal more practically. Figure 1 is a flow diagram showing an example of calculating such a total evaluation index, and I _A ,
By substituting I _B , I _C and I _D into the above formula, the total evaluation index of coking coal is calculated. The first
The abbreviations and analysis methods in the figure are as follows. C, H, O: Elemental analysis value (%) of carbon, hydrogen, and oxygen in coking coal (JIS M 8813) VM: Volatile content value (%) in coking coal (JIS M 8812) ASH: Elemental analysis value (%) of coking coal Ash content (%) (JIS M 8801) TS: Total sulfur content in coking coal (%) (JIS M 8813) [Example] Using coking coal A and B with properties shown in Table 1, the quality was evaluated. did.

[Table] Looking at the analysis results in Table 1, coking coal A has a lower volatile content and ash content than coking coal B, and a large amount of C.
The coal is considered to be of good quality because it contains carbon dioxide and has a high coke strength, but since the yield of each product during carbonization in a coke oven is unknown, a comprehensive and quantitative evaluation that takes into account the yield of by-products is required. I can't give up. On the other hand, when the quality of coking coals A and 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 carbonization 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> Coke (%) = −0.78VM + 98.40−C° Coal gas (Nm ² /T) = (3.11VM _E +227) × {60.38V
M _E −29.35(O)+3800}/4800 (as 4800Kcal/ ^Nm3 ) Coal tar (%)=0.38VM _E −3.17 <Calculation of energy required for carbonization> (Kcal/T) 22.8VM−1550(H/ C)+320(O/C)+810 However, C ⁰ =0.376e ^0.176(O) VM _E =VM−{1.12(O)+0.05}

[Table] Based on the calculated values in Table 2 and each standard unit price, each index given to the overall evaluation of coking coal is calculated as shown in Table 3. However, the disadvantages of blast furnace 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 (%) x
Average desulfurization cost required to remove 1% sulfur Disadvantage of deashing = Ash content (%) in coking coal x Average deashing cost required to remove 1% ash content

【table】

〔Effect of the invention〕

The present invention is configured as described above, and is effective in improving 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. Since this method comprehensively evaluates the quality of coking coal by taking into account the thermal energy required, the strength of the coke produced, etc., it is not just concerned with coke yield or quality, but also takes into account other positive and negative factors. The real value of coking coal can be evaluated more accurately.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 1 A: Coke obtained by carbonization of coking coal,
Each yield of coal gas and coal tar, B: Fuel consumption required for carbonization, C: Ash content and total sulfur content in the coke produced, D: The room temperature strength or strength after CO ₂ reaction of the coke produced, and these values are calculated. A quality evaluation method for coking coal for producing coke for iron making, which is characterized in that the quality of coking coal is evaluated according to the following formula. Total evaluation index = I _A − _{I B} − I _C + I _D where I _A : Total sum of (yield of each carbonization product × usefulness index) I _B : Total energy required for carbonization index I _C : Ash content in the coke produced and impurity index based on total sulfur content, I _D : strength index determined from the room temperature strength of the produced coke or the strength after CO ₂ reaction