Minimum-cost alloy adding method for steelmaking converter

Abstract

The invention relates to a lowest-cost alloy adding method for a steelmaking converter, which comprises the following steps of: determining common alloy for converter steelmaking, establishing an alloying cost calculation formula and constraint conditions for elements such as C, Si, Mn, Cr, P and N, and finally automatically solving the adding amount of each alloy when the alloy cost is the minimum value by adopting a multivariate linear programming principle and utilizing EXCEL. According to the method, a converter tapping deoxidation alloying lowest-cost scheme can be provided, the harmful element P, the residual element B and the like in the alloy are controlled, and the production requirements of high-quality low-cost variety steel are met.

Description

Technical Field

[0001] The invention relates to the technical field of converter steelmaking, and in particular to a method for adding alloys at the lowest cost to a steelmaking converter. Background Art

[0002] Xichang Steel & Vanadium Steel Plant produces over 270 different steel grades. With the exception of a small number of pre-deoxidation steel grades that do not undergo deoxidation and alloying in the converter, all other steel grades require deoxidation and alloying during tapping. Due to the diverse composition of steel grades produced in the converters, as well as their varying requirements for C and P at the converter end point, the types and quantities of alloys added during converter tapping vary significantly.

[0003] Traditionally, alloy additions are manually calculated by the furnace master or alloy worker using a calculator. Based on experience and the amount of carbon added to the alloy, low-cost alloys are often used to replace high-value alloys. This alloy calculation is highly arbitrary, and manual errors are common. Currently, our plant's L2 uses a Danieli Corus program, which can perform alloy calculations to a certain extent. However, its calculation logic still relies on traditional experience, using low-value alloys for alloying. Its biggest drawback is that it doesn't consider the impact of residual elements such as B and harmful elements such as P on the final composition of the molten steel, which can easily cause harmful elements such as these to exceed standards. Summary of the Invention

[0004] In response to the above problems, the purpose of the present invention is to provide a method for the lowest cost alloy addition in a steelmaking converter, which can provide a lowest cost solution for deoxidation and alloying of converter steel, and control harmful elements P and residual elements B in the alloy to meet the production needs of high-quality and low-cost steel varieties.

[0005] The technical solution adopted in the present invention is as follows:

[0006] The present invention provides a method for adding alloys at the lowest cost to a steelmaking converter, which specifically comprises the following steps:

[0007] S1. Identify the commonly used alloys for converter steelmaking, including:

[0008] Si-added alloys: ferrosilicon (X1, Q1), manganese silicon alloy (X2, Q2);

[0009] Mn-added alloys: manganese silicon alloy (X2, Q2), high carbon ferromanganese (X3, Q3), medium carbon ferromanganese (X4, Q4), low carbon ferromanganese (X5, Q5), metallic manganese (X6, Q6);

[0010] Cr-enhanced alloys: medium carbon ferrochrome (X7, Q7), low carbon ferrochrome (X8, Q8);

[0011] Among them, X1-X8 are the addition amounts of 8 alloys during alloying, and Q1-Q8 are the prices of 8 alloys;

[0012] S2. The cost of converter alloying is determined by the alloy selection when alloying Si, Mn, and Cr: Alloying cost = (X1×Q1+X2×Q2+X3×Q3+X4×Q4+X5×Q5+X6×Q6+X7×Q7+X8×Q8) min ;

[0013] Q1-Q8 are fixed values, that is, solving for the minimum alloy cost under different alloy addition amounts;

[0014] S3. Constraining the carbon element according to the carbon content of manganese silicon alloy, high carbon ferromanganese, medium carbon ferromanganese, low carbon ferromanganese and medium carbon ferrochrome;

[0015] S4. Constrain the Si element according to the Si addition amount of ferrosilicon, ferromanganese alloy, medium carbon ferromanganese and low carbon ferromanganese;

[0016] S5. Constrain the Mn element according to the Mn content of manganese silicon alloy, high carbon ferromanganese, medium carbon ferromanganese, low carbon ferromanganese and metallic manganese;

[0017] S6. Constraining the Cr element according to the Cr addition amount of medium carbon ferrochrome and low carbon ferrochrome;

[0018] S7. Constraining the P element according to the P addition amount of all alloys;

[0019] S8. Constraining the N element according to the N addition amount of all alloys;

[0020] S9. Constrain the residual element B in the steel grade according to the amount of B added to the manganese silicon alloy;

[0021] S10. Based on the constraints of steps S3-S9, the principle of multivariate linear programming is adopted and EXCEL is used to automatically solve the amount of each alloy added when the alloy cost in step S2 is minimized.

[0022] Furthermore, in step S3, the C constraint condition is: X2×C2+X3×C3+X4×C4+X5×C5+X7×C7≤(C addition target-end point C)×molten steel amount.

[0023] Furthermore, in step S4, the Si constraint condition is: X1×Si1+X2×Si2+X4×Si4+X5×Si5=Si addition target×molten steel amount÷yield.

[0024] Furthermore, in step S5, the Mn constraint condition is: X2×Mn2+X3×Mn2+X4×Mn2+X5×Mn2+X6×Mn2=(Mn addition target-residual Mn)×molten steel amount÷yield.

[0025] Furthermore, in step S6, the Cr constraint condition is: X7×Cr7+X8×Cr8=(Cr addition target-residual Cr)×molten steel amount÷yield.

[0026] Furthermore, in step S7, the P constraint condition is: X1×Q1+X2×Q2+X3×Q3+X4×Q4+X5×Q5+X6×Q6+X7×Q7+X8×Q8≤P×molten steel quantity.

[0027] Furthermore, in step S8, the N constraint condition is: X1×N1+X2×N2+X3×N3+X4×N4+X5×N5+X6×N6+X7×N7+X8×N8≤N×molten steel amount.

[0028] Furthermore, in step S9, the constraint condition B is: X2×B2≤steel judgment B×molten steel quantity.

[0029] Furthermore, the alloy addition amount X1-X8≥0, and an upper limit is imposed when a single alloy is added with a single element, that is, the addition amount is required to be ≤ a certain alloy element addition target × molten steel volume ÷ yield.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] By adopting the lowest-cost alloy addition method for a steelmaking converter proposed in the present invention, low-value alloys can more accurately replace high-value alloys during converter alloying calculations, harmful elements such as P and B introduced into the alloy can be controlled, and the economic benefits of alloy cost reduction are significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention provides a schematic flow chart of a method for the lowest-cost alloy addition in a steelmaking converter. DETAILED DESCRIPTION

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] See attached Figure 1 The present invention proposes a method for adding alloys at the lowest cost to a steelmaking converter, and the specific implementation process includes the following steps:

[0035] S1. Identify the commonly used alloys for converter steelmaking, including:

[0036] Si-added alloys: ferrosilicon (X1, Q1), manganese silicon alloy (X2, Q2);

[0037] Mn-added alloys: manganese silicon alloy (X2, Q2), high carbon ferromanganese (X3, Q3), medium carbon ferromanganese (X4, Q4), low carbon ferromanganese (X5, Q5), metallic manganese (X6, Q6);

[0038] Cr-enhanced alloys: medium carbon ferrochrome (X7, Q7), low carbon ferrochrome (X8, Q8);

[0039] Among them, X1-X8 are the addition amounts (kg) of the eight alloys when alloying a certain type of steel, and Q1-Q8 are the prices of the eight alloys (yuan / kg).

[0040] S2. The cost of converter alloying is mainly determined by the alloy selection when alloying the three elements Si, Mn and Cr: Alloying cost = (X1×Q1+X2×Q2+X3×Q3+X4×Q4+X5×Q5+X6×Q6+X7×Q7+X8×Q8) min ;

[0041] For Q1-Q8 prices, which are fixed values, the lowest alloy cost under different alloy addition amounts is solved.

[0042] Since alloying elements such as C, Si, Mn, and Cr will be introduced into the alloy, harmful elements such as P and N will also be introduced. Therefore, during alloying, it is necessary to consider adding elements such as C, Si, Mn, and Cr to the target value of the steel grade, and harmful elements such as P and N must be lower than the upper limit value of steel judgment, that is, there are certain constraints.

[0043] The C, Si, Mn, Cr, P, and N introduced into the alloy are defined as follows:

[0044] Table 1 Definition of element contents in 8 alloys

[0045]

[0046] In order to simplify the calculation, according to the alloy test composition, some alloys have a small increase in C, Si, Mn, Cr and P, N, so the alloy addition amount is not considered:

[0047] S3. Regarding the increase in C element, the main considerations are the increase in C of manganese silicon alloy, high carbon ferromanganese, medium carbon ferromanganese, low carbon ferromanganese and medium carbon ferrochrome, namely:

[0048] C constraint condition: X2×C2+X3×C3+X4×C4+X5×C5+X7×C7≤(C addition target - end point C)×molten steel volume;

[0049] S4. For Si element, the main considerations are ferrosilicon, ferromanganese alloy, medium carbon ferromanganese and low carbon ferromanganese to increase Si, namely:

[0050] Si constraint condition: X1×Si1+X2×Si2+X4×Si4+X5×Si5=Si addition target×molten steel volume÷yield rate;

[0051] S5. For the Mn element, we mainly consider manganese silicon alloy, high carbon ferromanganese, medium carbon ferromanganese, low carbon ferromanganese and metallic manganese to increase Mn, namely:

[0052] Mn constraint condition: X2×Mn2+X3×Mn2+X4×Mn2+X5×Mn2+X6×Mn2=(Mn addition target-residual Mn)×molten steel volume÷yield rate;

[0053] S6. For the Cr element, the main considerations are medium carbon ferrochrome and low carbon ferrochrome to increase Cr, namely:

[0054] Cr constraint condition: X7×Cr7+X8×Cr8=(Cr addition target-residual Cr)×molten steel volume÷yield;

[0055] S7. For P element, all alloys are considered to increase P, that is:

[0056] P constraint condition: X1×Q1+X2×Q2+X3×Q3+X4×Q4+X5×Q5+X6×Q6+X7×Q7+X8×Q8≤P×molten steel quantity;

[0057] S8. For N element, all alloys are considered to increase N, that is:

[0058] N constraint condition: X1×N1+X2×N2+X3×N3+X4×N4+X5×N5+X6×N6+X7×N7+X8×N8≤N×molten steel amount;

[0059] S9. For the B element, the main consideration is to increase the B of manganese silicon alloy, that is:

[0060] B constraint condition: X2×B2≤B×molten steel volume;

[0061] In order to control the rationality of the calculation results of alloy addition, the alloy addition amounts X1-X8 are all limited to "≥0", and an upper limit is imposed when a single alloy is added with a single element, that is, the addition amount is required to be ≤ a certain alloy addition target × molten steel volume ÷ yield.

[0062] S10. Based on the constraints and rationality control conditions of steps S3-S9, the principle of multivariate linear programming is adopted and EXCEL is used to automatically solve the various alloy addition amounts for the minimum alloy cost in step S2, which is the alloy addition method.

[0063] The present invention solves based on the principle of multiple linear regression:

[0064] 1. Mathematical model

[0065] Objective function: a linear function to be maximized or minimized, in the form

[0066] z=c1x1+c2x2+…+c n x n

[0067] where c i is the coefficient, x i is the decision variable.

[0068] Constraints: These consist of linear inequalities or equations, such as:

[0069]

[0070] All constraints together define the region of feasible solutions.

[0071] 2. Properties of the feasible solution region

[0072] Convex Sets and Convex Polyhedra: The feasible region is the intersection of multiple half-spaces, forming a convex set. If it is a bounded closed set, it is called a convex polyhedron.

[0073] Vertex (Extreme Point): The optimal solution must appear at the vertex of the feasible region (if a bounded solution exists). This is a basic theorem of linear programming, determined by the linear properties of the objective function.

[0074] 3. Existence and conditions of solutions

[0075] Feasibility: There exists at least one solution that satisfies all constraints.

[0076] Boundedness: If the objective function is bounded on the feasible region (e.g., it does not grow infinitely in a maximization problem), then an optimal solution exists.

[0077] Uniqueness and multiple solutions: The optimal solution may be unique at a vertex, or there may be infinite solutions along a certain edge / face (when the objective function is parallel to the edge / face).

[0078] 4. Solution method

[0079] Simplex method (classic algorithm): By traversing the vertices of the feasible region, the objective function value is gradually improved until the optimal solution is found. Its efficiency depends on the structure of the problem, but in the worst case, it can be exponentially complex.

[0080] Interior point method: Approaches the optimal solution from the interior of the feasible region, suitable for large-scale problems, and has polynomial time complexity.

[0081] Standard form conversion: The problem is usually converted to the following form for solution:

[0082] Minimize c T x

[0083] Ax=b,x≥0.

[0084] Matters not described in detail in this invention are all known technologies.

[0085] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for adding alloys at the lowest cost in a steelmaking converter, characterized in that: The method comprises the following steps: S1. Identify the commonly used alloys for converter steelmaking, including: Si-added alloys: ferrosilicon (X1, Q1), manganese silicon alloy (X2, Q2); Mn-added alloys: manganese silicon alloy (X2, Q2), high carbon ferromanganese (X3, Q3), medium carbon ferromanganese (X4, Q4), low carbon ferromanganese (X5, Q5), metallic manganese (X6, Q6); Cr-enhanced alloys: medium carbon ferrochrome (X7, Q7), low carbon ferrochrome (X8, Q8); Among them, X1-X8 are the addition amounts of 8 alloys during alloying, and Q1-Q8 are the prices of 8 alloys; S2. The cost of converter alloying is determined by the alloy selection when alloying Si, Mn, and Cr: Alloying cost = (X1×Q1+X2×Q2+X3×Q3+X4×Q4+X5×Q5+X6×Q6+X7×Q7+X8×Q8) min ; Q1-Q8 are fixed values, that is, solving for the minimum alloy cost under different alloy addition amounts; S3. Constraining the carbon element according to the carbon content of manganese silicon alloy, high carbon ferromanganese, medium carbon ferromanganese, low carbon ferromanganese and medium carbon ferrochrome; S4. Constrain the Si element according to the Si addition amount of ferrosilicon, ferromanganese alloy, medium carbon ferromanganese and low carbon ferromanganese; S5. Constrain the Mn element according to the Mn content of manganese silicon alloy, high carbon ferromanganese, medium carbon ferromanganese, low carbon ferromanganese and metallic manganese; S6. Constraining the Cr element according to the Cr addition amount of medium carbon ferrochrome and low carbon ferrochrome; S7. Constraining the P element according to the P addition amount of all alloys; S8. Constraining the N element according to the N addition amount of all alloys; S9. Constrain the residual element B in the steel grade according to the amount of B added to the manganese silicon alloy; S10. Based on the constraints of steps S3-S9, the principle of multivariate linear programming is adopted and EXCEL is used to automatically solve the amount of each alloy added when the alloy cost in step S2 is minimized.

2. The method for adding alloys at the lowest cost to a steelmaking converter according to claim 1, wherein: In step S3, the C constraint condition is: X2×C2+X3×C3+X4×C4+X5×C5+X7×C7≤(C addition target-end point C)×molten steel amount.

3. The method for lowest cost alloy addition in a steelmaking converter according to claim 1, wherein: In step S4, the Si constraint condition is: X1×Si1+X2×Si2+X4×Si4+X5×Si5=Si addition target×molten steel amount÷yield.

4. The method for lowest cost alloy addition in a steelmaking converter according to claim 1, wherein: In step S5, the Mn constraint condition is: X2×Mn2+X3×Mn2+X4×Mn2+X5×Mn2+X6×Mn2=(Mn addition target-residual Mn)×molten steel amount÷yield.

5. The method for lowest cost alloy addition in a steelmaking converter according to claim 1, characterized in that: In step S6, the Cr constraint condition is: X7×Cr7+X8×Cr8=(Cr addition target-residual Cr)×molten steel amount÷yield.

6. The method for lowest cost alloy addition in a steelmaking converter according to claim 1, wherein: In step S7, the P constraint condition is: X1×Q1+X2×Q2+X3×Q3+X4×Q4+X5×Q5+X6×Q6+X7×Q7+X8×Q8≤P×molten steel amount.

7. The method for lowest cost alloy addition in a steelmaking converter according to claim 1, characterized in that: In step S8, the N constraint condition is: X1×N1+X2×N2+X3×N3+X4×N4+X5×N5+X6×N6+X7×N7+X8×N8≤N×molten steel amount.

8. The method for lowest cost alloy addition in a steelmaking converter according to claim 1, characterized in that: In step S9, the constraint condition B is: X2×B2≤B×molten steel amount.

9. The method for lowest cost alloy addition in a steelmaking converter according to claim 1, characterized in that: The alloy addition amount X1-X8≥0, and an upper limit is imposed when a single alloy is added with a single element, that is, the addition amount is required to be ≤ a certain alloy element addition target × molten steel volume ÷ yield rate.

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