JPH11264013A - Method for evaluating scrap value and system for determing ratio of scrap used by using this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantitatively clarify the influences of various kinds of scrap on the electric power, productivity, yield and impurities in a steel, etc., by calculating in multiple times and correcting so that the calculated value of unit requirement of power etc., calculated by preliminarily setting of characteristic values in factors of each scrap and the others agrees on the actual value to obtain the characteristic value. SOLUTION: The characteristic value T of the unit requirement of power, productivity, copper content in the steel, etc., in the unit of heat, is calculated with the equation T=Σ (aj .xj +bk .Zk )+C. In the equation, aj is the characteristic value in each kind of scrap ((j) is number of the kind of scrap),xj is the blending ratio of each scrap (Σxj =1), bk is the characteristic value in the factor except the scrap, Zk is the consumption in the factor except the scrap (unit requirement) and C is constant. The aj , bk and C are preliminarily set and the calculated value of T calculated with the equation and the actual value are compared, and the calculation and the correction are repeatedly executed so that both values agree, to obtain aj , bk and C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating the value of scrap and a system for determining the ratio of the amount of scrap used using the method.

[0002]

2. Description of the Related Art Conventionally, it has been widely practiced to mix a large amount of scrap to produce crude steel. Conventionally, the compounding ratio of scrap has been determined by purchasing cheap scraps based on the past experience and situation judgment of humans within a range that satisfies the chemical composition standard and can be actually operated.

[0003] It is very important to reduce the production cost of crude steel, but there has been a limit to the cost reduction in the conventional method of simply determining the composition of scrap from the viewpoint of cost. That is, since the arrival status and purchase price of scrap are dynamic depending on market conditions every day, it is completely impossible to manufacture crude steel from scrap at the minimum cost without deteriorating the quality of crude steel. It was impossible.

[0004] In order to solve such problems, the present applicant has set a scrap usage ratio which can dynamically minimize the total production cost including the steelmaking operation cost without deteriorating the quality of crude steel. Develop the desired system,
I applied for a patent earlier.

[0005] Although the above method is a very convenient method, the evaluation of the value of scrap used in the calculation of the above system has been evaluated by multiple regression analysis of operation data or sole melting for each scrap brand.

[0006]

However, the above-mentioned multiple regression analysis often reverses theoretical and empirical values, and has a disadvantage of lacking reliability.

[0007] In addition, the method of evaluating by scrap dissolving for each scrap brand requires enormous labor, there are scraps that are difficult to dissolve alone, the dissolution behavior may differ when mixed alone and in addition to the experiment. If the number is small, there is a problem that the dispersion in the scrap is greatly affected. In addition, there is a problem that it is extremely difficult to cope with a change over time.

[0008] The invention described in claim 1 of the present invention,
It is an object of the present invention to provide a method for evaluating the value of various scraps, which can quantitatively clarify the effects of various scraps on power, productivity, yield, impurity elements in steel, and the like.

[0009] The invention described in claim 3 is the first invention.
It is an object of the present invention to provide a system for obtaining a scrap usage ratio that can minimize the total production cost including the steelmaking operation cost by using the method.

[0010]

The structure of the invention according to claim 1 of the present invention along the object, according to an aspect of the following formula (I): T = Σ ( a j · x j + b k · z k) + C (I) (where T represents characteristic values such as power consumption per unit of cheige, productivity, copper content in steel, etc., a _j is a characteristic value for each scrap brand ( _j is the number of scrap brands) _Xj
Represents the mixing ratio of each scrap (Σx _j = 1), and b _k
Represents a characteristic value of a factor other than scrap, z _k represents a usage amount (basic unit) of a factor other than scrap, and C is a constant. Note that T, x _j and z _k are known. ) To a
_j , b _k and C are provisionally set from the conventional knowledge, and the calculated value of T is calculated and compared with the actual value. The calculated value and the actual value are calculated and corrected many times so that the actual value is the same. _j , b _k and C
Is obtained.

The invention according to claim 3 is based on the following formula (I)
I): cost S = Σ (x1 · (c1 + Δc _i ) + x2 · (c2 + Δc ₂ ) +... + Xi · (ci + Δc _i )) (II) (where x1 to xi are the scraps of each scrap) Basic unit of mixing (t
/ T) represents, C1～ci represents price (yen / t) of the scrap, and .DELTA.c _i represents the value of the scrap, i is a number from up to several tens. ) Using the objective function minimizing the scrap blending cost, calculating the above variables many times by computer, changing the above variables, and within the constraints of the collection capacity, operational constraints, and contained metal constraints, In the system for calculating the usage ratio of each scrap that minimizes the cost S, the value difference Δc _{i of} each scrap
Is calculated by using the scrap usage ratio calculated by the formula (I) according to the first aspect of the present invention.

[0012] In short, the system of the present invention for determining the usage ratio of scrap uses the mixing ratio of each scrap used for steelmaking as a variable, and the purchase price and use value of each scrap as constants, and sequentially changing the above variables to obtain a large number. Calculate
The gist of the present invention is to find the above variables that minimize the steelmaking operation cost as much as possible within the constraints of the collection capacity, operation restrictions, and metal content restrictions. Although the above calculation uses a computer, a method of using a computer-based arithmetic system as in the present invention has not been known at all.

[0013]

Next, an embodiment of the present invention will be described. Examples of the scrap used in the present invention include shredders, snakes, new cuttings, C presses, dalai powder, pig dalai,
Pig iron, late pig iron, generated waste, special waste, and the like. It is not necessary to use all of the above-mentioned scraps, and it goes without saying that scraps other than these may be used, and it is better to replace expensive products with cheap products. In other words, it is preferable to acquire a wide range of information and purchasing power of scrap, dynamically evaluate the value of scrap according to the situation, make more advantageous purchases, and mix the scrap.

In order to minimize the steelmaking operation cost, the usage ratio that minimizes the following objective function (1) is obtained under the following constraint (2).

(1) Objective function The following equation (II): Cost S = Σ (x1 · (c1 + Δc _i ) + x2 · (c2 + Δc ₂ ) +... + Xi · (ci + Δc _i )) (II) ( In the formula, x1 to xi represent the unit consumption (t) of each scrap.
/ T) represents, C1～ci represents price (yen / t) of the scrap, and .DELTA.c _i represents the value of the scrap, i is a number from up to several tens. ) Is used to determine the usage ratio of each scrap that minimizes the cost S calculated by the formula.

The value difference Δc of each scrap may be determined from the difference between scraps by clarifying quantitatively the effects of various scraps on power, productivity, yield, impurities in steel, and the like.

Specifically, the following equation (I): T = Σ (a _j x _j + b _k z _k ) + C (I) (where T is the power consumption unit in the unit of chy, production sex,
A _j represents a characteristic value of each scrap brand ( _j represents the number of scrap brands), and x _j represents a mixing ratio of each scrap (Σx _j = 1). ), And b _k represents a characteristic value of a factor other than scrap, and z _k
Indicates the usage (basic unit) of factors other than scrap.
Is a constant. Note that T, x _j and z _k are known. )
From a _j, b _k and C were compared with the calculated value and the actual value of the T calculated provisionally set from the conventional knowledge, as a calculated value and the actual value match a _j, b _k and C And the effects of various scraps due to power, productivity, yield, impurity elements in steel, etc. should be clarified quantitatively.

In the above formula (I), a _j , b _k, etc. are provisionally set from conventional knowledge and the like, and the calculation result Tcal is compared with the actual value T as shown in FIG. At the time of comparison, it is convenient to prepare and use a graph of the actual value T versus the calculation result Tcal as shown in FIG.

The calculation is repeated by a computer so that the actual value T and the calculation result Tcal in all the operation data coincide as much as possible, and a _j , b _k and C are corrected as shown in FIG.
decide. The calculation can be easily performed using commercially available general-purpose spreadsheet software. Preferably, a _j , b _k and C are set so as to minimize Σ (T−Tcal) ² in all operation data.
Modify and decide. In this way, the optimum value can be clarified numerically.

The same operation is performed for each characteristic value to quantitatively clarify the influence of scrap on the power, productivity, yield, impurity elements in steel, and the like. Characteristic values that are apparent in principle or empirically can be applied as they are. For example, the contribution of C in pig iron and blown oxygen to the power consumption unit can be mentioned.

The method of the present invention using the formula (I) can easily cope with changes in operations and the like. Therefore, depending on the time,
Although the quality changes even in the case of steady scrap, a _j and b _k can be easily reviewed periodically according to the method using the formula (I).

Basically, scraps having a low total cost are used, but the chemical composition, the actual operable range, and the purchaseable amount limit become constraints, and the scrap is determined in consideration of the limit (for the calculation system). Take in). It is preferable that i have several hundred types of frames in a computer arithmetic system, but in the arithmetic system of the present invention, one to several tens of types are sufficient.

The scrap characteristic value a _j obtained as described above: the unit power consumption, productivity, yield, etc. can be regarded as the value of scrap. Accordingly, the value difference Δc of each scrap brand is, for example, a value difference Δc (new) = c (new) −c (heavy) of a newly-established value if the standard is a heavy value.
Becomes

(2) Restrictions (A) Metal component Trump element: Σ (each Trump element content of each scrap · xi) ≦ specification value of each Trump element, Fe: Σ (Fe content of each scrap · xi) ≧ 1.0
And (B) Actual operable range / purchasable amount limit (restriction on collection capacity and operation) Restriction on upper and lower limits of blending amount of each scrap: xi ≧ 0, a ≦
xi ≦ b (where a and b represent upper and lower limits of the composition determined by the collection capacity and operational restrictions, and i represents the above number)
It is represented by

As the above-mentioned playing card element, Cu,
At least one kind of impurities such as Sn, Ni, Mo, and Pb that cannot be removed by an electric furnace, that is, Cu: Σ (Cu content of each scrap · xi) ≦ specification value, Sn: Σ (Sn content of each scrap · xi) ≦ specified value, Ni: Σ (Ni content of each scrap · xi) ≦ specified value, Mo: Σ (Mo content of each scrap · xi) ≦ specified value and Pb: Σ (Pb content of each scrap) Xi) It is better to satisfy at least one of the standard values.

In particular, as a playing card element, Cu
And Sn, that is, Cu: Σ (Cu content of each scrap · xi) ≦ specified value and Sn: Σ (Sn content of each scrap · xi) ≦ specified value. Cr, P, S and As can be removed in an electric furnace,
Since it is an impurity, it is good to consider these contents when evaluating the value of scrap.

In the present invention, the scrap usage ratio is determined so that the total cost including the steelmaking operation cost can be minimized. FIG. 3 is a block diagram showing an operation image of the present invention. In the linear operation, the purchase price (c) and the difference in use value (Δc) are constants. Since these values change daily, they are calculated periodically (for example, every two days to one week). The scrap usage ratio is changed so that the total cost is always minimized.

The a and b of a ≦ xi ≦ b representing the upper and lower limits of each scrap are the above-mentioned predicted amount of arrival, solubility,
These are the upper and lower limits of the composition determined by operational restrictions such as bulk and the content of metal components. The minimum value of the linear operation of the above equation (1) is obtained within a range that satisfies the constraint on the arrival amount prediction (upper limit, lower limit) and the use restriction (the constraint conditions A and B). Use restrictions are operational restrictions such as solubility and bulk of the scrap, and restrictions on the use of the content of Cu, Sn and other tramp elements. The use value difference Δc of each scrap can be obtained from the above equation (I).

The predicted arrival amount (upper limit, lower limit) changes daily, and the purchase amount also affects the purchase price (c). Therefore, the purchase price (c) when the arrival is changed is changed. ) Needs to be predicted.

Using the above formula (II), a computer is used to change the mixing ratio of each scrap and calculate a large number of times to obtain a mixing ratio that minimizes the total cost within the above-mentioned constraints. The formulation determined as described above is followed up with the actual amount of arrival and the actual price, corrected if necessary, and further corrected so that appropriate operation can be obtained if necessary due to actual operation defects, and the scrap composition is determined. do.

Next, an example of calculation in the case of using the above-mentioned formula (I) and setting the power consumption unit as a characteristic value will be described. The power consumption unit a _j for each scrap brand (A ′ to D ′) is set as follows, for example. A ': 2.5 kwh / t /% B': 3.0 kwh / t /% C ': 1.0 kwh / t /% D': 3.5 kwh / t /%

The power consumption units a _j of factors other than scrap are set as follows. ^{Oxygen: -3 kwh / t / Nm 3} % / t kerosene: the -5.5kwh / t / l / t constant term c is denoted by 140kwh / t.

In a certain charge, it is assumed that the scrap composition and the unit consumption of kerosene / oxygen are as follows. A ': 50% B': 15% C ': 15% D': 20% Oxygen: 20 Nm ³ / t Kerosene: 10 l / t

The calculated value of the unit power consumption of the charge is as follows. T = 2.5 × 50 + 3.0 × 15 + 1.0 × 15 + 3.
5 × 20−3 × 20−5.5 × 10 + 140 = 280k
wh / t

In this manner, the calculated value and the actual value are compared by changing a _j variously, and a _j , b _k and c are corrected as shown in FIG. 2 to obtain a _j .

When 100% of heavy and new cutting are used, respectively, and oxygen and kerosene are not used, the calculated values of the power consumption unit are 390 and 440 kWh / t, respectively. The power consumption is directly related to the cost (1 kwh = X yen).
X yen can be made cheaply.

In addition to the power consumption rate, the yield and productivity are characteristic values directly related to the production cost, and are evaluated in the same manner as described above. Impurity elements (Cu, Sn, etc.) in steel are characteristic values related to quality, and when there are restrictions on quality, they are the highest priority evaluation items.

Next, using the above formula (II), the upper limit of Sn is fixed at 0.04%, and a typical example is Cu 0.40%
The calculation result of the optimal solution in the case of is shown. The constraint conditions are Cu: Σ (Cu content of each scrap · xi) ≦ standard value and Sn: Σ (Sn content of each scrap · xi) ≦ standard value, Fe: ： (Fe content of each scrap · xi) ≧ 1.
0 and restrictions on the upper and lower limits of the amount of each scrap: xi ≧ 0, a ≦
xi ≦ b In the above equation (1) and i in the constraint condition, i is 1 in the above embodiment.
And 10.

The a and b of the above constraint conditions are set assuming approximate numbers matching the actual situation. In an actual arithmetic system, a person determines and inputs the situation in that phase. Table 1 shows the result calculated by the computer as described above.
Shown in In the table, the scrap unit price is blank, but the actual calculation was based on our purchase price.

[0040]

[Table 1]

As described above, the optimum solution is determined. still,
The current standards in Table 1 satisfy the chemical composition standards based on past experience, and determined the scrap usage ratio for each of seven types of scraps purchased based on a fixed value evaluation within the range of practical operation. One of the things.

The above calculation is normally performed once a week, and when a change in the stock status, purchase price and market conditions is felt, the calculation is performed each time (about 10 times a month in total), and the total of the total including the operating costs is calculated. Steelmaking costs can always be dynamically minimized.

[0043]

According to the first aspect of the present invention, it is possible to quantitatively and easily clarify the effects of various scraps on power, productivity, yield, impurity elements in steel, and the like. And the value of various scraps can be easily evaluated.

According to the third aspect of the present invention, the total production cost including the steelmaking operation cost can be adjusted in accordance with the market conditions such as the scrap receiving status and the purchase price without deteriorating the quality of the crude steel. And can easily be dynamically minimized at all times.

[0045]

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a calculation result Tcal and an actual value.

FIG. 2 is a graph in which a calculation result Tcal and an actual value match as much as possible.

FIG. 3 is a block diagram showing a calculation image of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Harutoku Harutoku 5th-9th Yonbancho, Chiyoda-ku, Tokyo Topy Engineering Co., Ltd. (72) Inventor Seiji Yamada 5th-9th Yonbancho, Chiyoda-ku, Tokyo Topy Industries, Ltd. (72) Inventor Yuji Yoshikawa 5th-9th, Yonbancho, Chiyoda-ku, Tokyo Topy Industries, Ltd.

Claims (6)

[Claims] 1. The following equation (I): T = Σ (a _j x _j + b _k z _k ) + C (I) (where T is the power consumption unit in the unit of cheige, productivity, copper content in steel) Represents a characteristic value such as quantity, a _j represents a characteristic value for each scrap brand ( _j represents the number of scrap brands), and x _j
Represents the mixing ratio of each scrap (Σx _j = 1), and b _k
Represents a characteristic value of a factor other than scrap, z _k represents a usage amount (basic unit) of a factor other than scrap, and C is a constant. Note that T, x _j and z _k are known. ) To a
_j , b _k and C are provisionally set from the conventional knowledge, and the calculated value of T is calculated and compared with the actual value. The calculated value and the actual value are calculated and corrected many times so that the actual value is the same. _j , b _k and C
Value evaluation method for quantitatively clarifying the effects of various scraps on power, productivity, yield, impurity elements in steel, etc. 2. The evaluation method according to claim 1, wherein a _j , b _k and C are corrected to obtain a _j so as to minimize Σ (T−Tcal) ² in all operation data. 3. The following equation (II): Cost S = Σ (x1 · (c1 + Δc _i ) + x2 · (c2 + Δc ₂ ) +... + Xi · (ci + Δc _i )) (II) x1 to xi are the basic unit of mixing of each scrap (t
/ T) represents, C1～ci represents price (yen / t) of the scrap, and .DELTA.c _i represents the value of the scrap, i is a number from up to several tens. ) Using the objective function minimizing the scrap blending cost, calculating the above variables many times by computer, changing the above variables, and within the constraints of the collection capacity, operational constraints, and contained metal constraints, In the system for calculating the usage ratio of each scrap that minimizes the cost S, the value difference Δc _{i of} each scrap
The system for calculating a scrap usage ratio calculated by the formula (I) according to claim 1. 4. The constraint condition of the contained metal is as follows: Trump element: Σ (each Trump element content of each scrap · xi) ≦ specification value of each Trump element, Fe: Σ (Fe content of each scrap · xi) ) ≧ 1.
0, and the restrictions on the collection capacity and operation are limited by the upper and lower limits of the blending amount of each scrap: xi ≧ 0, a ≦
xi ≦ b (where a and b represent upper and lower limits of the composition determined by the collection capacity and operational restrictions, and i represents the above number)
5. The system according to claim 4, represented by: 5. The card according to claim 1, wherein the playing element is Cu, Sn,
The system according to claim 4, wherein the system is at least one of impurities such as Ni, Mo, and Pb that cannot be removed by an electric furnace. 6. The tramp element according to claim 5, wherein Cu: Σ (Cu content of each scrap · xi) ≦ standard value, and Sn: Σ (Sn content of each scrap · xi) ≦ standard value. The described system. /