A method for batching scrap steel for converter smelting

Abstract

The present invention belongs to the field of steelmaking, and relates to a method for batching scrap steel for converter smelting, including: constructing a relationship between the yield and cooling effect of different types of scrap steel according to the scrap steel yield and the cooling effect corresponding to the scrap steel; constructing a model equation of the converter smelting waste heat temperature, the scrap steel addition ratio and its corresponding cooling effect, and the total amount of scrap steel added, and constructing a relationship function between the addition amount of different types of scrap steel and the total amount of scrap steel added; selecting the scrap steel type and its addition ratio, and obtaining the cooling effect corresponding to the scrap steel type through the relationship; then obtaining the total amount of scrap steel added through the model equation according to the cooling effect and addition ratio corresponding to the scrap steel, and the converter smelting waste heat temperature, and obtaining the addition amount of different types of scrap steel through the relationship function. The batching method of the present invention is scientific and reasonable, has strong versatility, can reduce the number of manual calculations, meets the real-time use of the online production process, reduces abnormal working conditions, and can save production raw material costs and energy consumption costs for users.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking, and in particular relates to a method for proportioning scrap steel for converter smelting. Background Art

[0002] As the price of imported iron ore from abroad has risen sharply, the profit margins of domestic steel companies have been continuously squeezed. In order to get rid of the heavy dependence on imported iron ore, scrap steel as a recyclable green resource has become the first choice of various steel companies. In the process of rapid economic development in my country, the accumulation of scrap steel in society has increased rapidly, scrap steel resources have become more and more abundant, and the price of scrap steel has fluctuated frequently. The proportion of molten iron and scrap steel in the converter steelmaking process fluctuates with market conditions, which has become a normal operation of steel companies. However, the existing scrap steel has not been classified and added, and the addition is disordered and blind. It often happens that scrap steel blocks the furnace and the blowing auxiliary gun (i.e., temperature measuring gun) model has large deviations. At present, the calculation method of the existing blast furnace batching design is usually complicated, involving multiple factors, and the calculation is relatively complicated, which is insufficient to meet market demand.

[0003] For example, CN110516402A provides a method for optimizing the batching of scrap steel in an electric arc furnace, and the process is as follows: according to the target composition of the finished product, the bulk density of the scrap steel, the oxidation rate of the scrap steel elements, the recovery rate of the alloy elements and the bulk density requirements of the scrap steel, the constraint equation of the target composition of the finished product, the constraint equation of the target bulk density of the scrap steel, the constraint equation of the quality of the scrap steel and the alloy, and the optimization batching objective function are constructed, and a linear programming mathematical model is constructed according to the equations, and the addition amount of the scrap steel and the alloy is calculated by the linear programming mathematical model. Although this patent application can effectively reduce the cost of electric furnace smelting, its calculation process is complicated and the workload is large. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of the existing batching method being complicated, the workload being large, and the furnace being blocked by scrap steel due to inappropriate batching in the prior art, and to provide a batching method for scrap steel for converter smelting. The batching method has a relatively simple process and a small workload. The batching is made according to the appropriate batching composition, which effectively reduces the phenomenon of furnace mouth being blocked due to increasing the inappropriate amount of scrap steel added, thereby reducing the cost of raw materials and energy consumption.

[0005] In order to achieve the above object, the present invention provides a method for batching scrap steel for converter smelting, comprising the following steps:

[0006] (1) According to the scrap steel recovery rate and the cooling effect corresponding to the scrap steel, the relationship between the recovery rate and the cooling effect corresponding to different types of scrap steel is constructed;

[0007] (2) Construct model equations for the converter smelting waste heat temperature, scrap steel addition ratio and its corresponding cooling effect, and the total amount of scrap steel added, and construct relationship functions between the addition amount of different types of scrap steel and the total amount of scrap steel added;

[0008] (3) Select the type of scrap steel and its addition ratio, and obtain the cooling effect corresponding to the type of scrap steel through the relationship between the recovery rate and the cooling effect according to the recovery rate corresponding to the type of scrap steel; then, according to the cooling effect and addition ratio corresponding to the scrap steel, as well as the converter smelting waste heat temperature, obtain the total amount of scrap steel added through the model equation, and obtain the addition amount of different types of scrap steel through the relationship function.

[0009] β=α3η 3 +α2η 2 +α1η+α0

[0010] Preferably, in step (1), the relationship between the yield and the cooling effect is:

[0011] In the formula,

[0012] η is the scrap steel recovery rate;

[0013] β is the cooling effect of scrap steel, °C / t;

[0014] α i is the temperature coefficient, i=0, 1, 2 or 3.

[0015] Preferably, α3=0.00109; α2=-0.21334; α1=12.5-13.5; α0=-220 to -230.

[0016] Preferably, the calculation formula for the converter smelting waste heat temperature is constructed by the cooling temperature of the added coolant, the heating temperature of the heat generating agent and the temperature change caused by the heat released by oxidation of the difference in silicon content between the silicon content in the molten iron and the silicon content in the standard molten iron.

[0017] Preferably, the calculation formula for the converter smelting waste heat temperature is:

[0018]

[0019] In the formula,

[0020] ΔT=T e -T d

[0021] b=h×12.5

[0022] j is the type of coolant and exothermic agent added in addition to scrap steel;

[0023] W j is the amount of coolant and exothermic agent added in addition to scrap steel, t;

[0024] β j is the cooling effect or heating effect of the coolant or heating agent, ℃ / t;

[0025] h is oxygen consumption per ton of steel, m 3 / t;

[0026] b is the temperature correction coefficient, °C;

[0027] T Si is the temperature of the standard deviation of Si contained in molten iron, °C;

[0028] T e is the temperature of adding molten iron, ℃;

[0029] T d is the pouring furnace temperature, ℃.

[0030] More preferably, T Si =([Si] ％ -[Si0] ％ )×200

[0031] in,

[0032] [Si] ％ is the mass percentage of silicon in molten iron, %;

[0033] [Si0] ％ is the standard mass percentage of silicon in molten iron, %.

[0034] Preferably, the model equation is:

[0035]

[0036] In the formula,

[0037] i is the type of scrap steel;

[0038] a i The proportions of different types of scrap steel to be added;

[0039] β i is the cooling effect corresponding to different types of scrap steel, ℃ / t;

[0040] W scrap is the total amount of scrap steel loaded, t.

[0041] Preferably, the relationship function is:

[0042] W sci =a i W scrap

[0043] Where W sci is the loading amount of different types of scrap steel, t.

[0044] Preferably, in step (3), the selection of the scrap steel type and its addition ratio is modified according to the scrap steel cost performance index, and the calculation formula of the scrap steel cost performance index is: cp =y÷η×γ×s×d

[0045] Where: F cp is the scrap steel cost performance index;

[0046] y is the price of scrap steel excluding tax;

[0047] η is the scrap steel recovery rate;

[0048] γ is the cooling effect coefficient;

[0049] s is the safety and environmental protection factor;

[0050] d is the influence coefficient of pile specific gravity.

[0051] Preferably, the method further comprises:

[0052] (4) calculating the iron-steel ratio according to the types of scrap steel selected in step (3) and their addition ratios and the obtained addition amounts of different types of scrap steel;

[0053] (5) selecting multiple groups of initial data, each group of initial data including the type of scrap steel selected in step (3) and its addition ratio, and repeating step (4);

[0054] (6) Select the group with the lowest iron-steel ratio in step (5) as the batching solution.

[0055] The present invention adopts the above-mentioned technical scheme, especially constructs the relationship between the yield and cooling effect of different types of scrap steel, and formulates a reasonable furnace addition model according to the different cooling effects of different types of scrap steel. On the basis of achieving the heat balance between converter molten iron and scrap steel, it can guide the increase of converter smelting production and reduce the cost of scrap steel composition structure.

[0056] The batching method of the present invention is scientific and reasonable, easy to use, and has strong versatility. It can reduce the number of manual calculations, meet the real-time use of online production processes, have good result optimization, reduce the occurrence of abnormal working conditions, save production raw material costs and energy consumption costs for users, and create considerable economic value for users.

[0057] The present invention also has the following advantages:

[0058] 1. The scrap steel structure is reasonably matched. The technicians in this field can independently select the scrap steel types and their proportions according to the market conditions, and are less affected by the price fluctuations of the scrap steel market;

[0059] Second, feeding into the furnace according to the optimized ratio is convenient for converter smelting furnace temperature control and conducive to the stability of the auxiliary gun model;

[0060] 3. Improve the smelting rhythm, reduce the number of furnace mouth blockages due to unreasonable ingredients, and shorten the converter smelting cycle.

[0061] Under the preferred embodiment of the present invention, molten iron conditions, steel tapping temperature, etc. are used as the basis for heat balance calculation, a model equation is constructed, and the cooling effect of different types of scrap steel is combined to calculate the required amount of molten iron and scrap steel according to the heat balance. This achieves the solution to the problem of scrap steel addition while reducing the iron-steel ratio of the converter, and maximizes the reduction of the scrap steel composition structure cost. DETAILED DESCRIPTION

[0062] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0063] In the present invention, "yield" refers to the ratio of molten steel to the total amount of scrap steel after the scrap steel is melted, measured by weight.

[0064] As mentioned above, the present invention provides a method for batching scrap steel for converter smelting, comprising the following steps:

[0065] (1) According to the scrap steel recovery rate and the cooling effect corresponding to the scrap steel, the relationship between the recovery rate and the cooling effect corresponding to different types of scrap steel is constructed;

[0066] (2) Construct model equations for the converter smelting waste heat temperature, scrap steel addition ratio and its corresponding cooling effect, and the total amount of scrap steel added, and construct relationship functions between the addition amount of different types of scrap steel and the total amount of scrap steel added;

[0067] (3) Select the type of scrap steel and its addition ratio, and obtain the cooling effect corresponding to the type of scrap steel through the relationship between the recovery rate and the cooling effect according to the recovery rate corresponding to the type of scrap steel; then, according to the cooling effect and addition ratio corresponding to the scrap steel, as well as the converter smelting waste heat temperature, obtain the total amount of scrap steel added through the model equation, and obtain the addition amount of different types of scrap steel through the relationship function.

[0068] The scrap steel batching method of the present invention constructs a relationship between the yield and cooling effect corresponding to different types of scrap steel, determines the temperature coefficient of the direct relationship between the two, so that there is a direct calculation relationship between the two, and the metering workload is significantly reduced; while in the prior art, since there are many factors affecting the scrap steel yield, the yields of different types of scrap steel are different, and the yields of the same type of scrap steel are also different. The general calculation method is more complicated and only provides an indirect relationship between the yield and the cooling effect.

[0069] Furthermore, the present invention further cooperates to construct model equations and relationship functions with the total amount of scrap steel added and different amounts of scrap steel added, which can reduce the iron-steel ratio while achieving thermal balance between molten iron and scrap steel in the converter, thereby guiding the increase in converter smelting production and reducing the cost of scrap steel structures; and can reduce the deviation of the oxygen lance blowing sub-lance model to within 20°C, making the blowing stable.

[0070] In the present invention, the proportion of scrap steel added refers to the proportion of the weight of different types of scrap steel to the total amount of scrap steel.

[0071] In step (1) of the present invention, a relationship between the recovery rate and the cooling effect can be obtained by fitting based on one or more existing (which can be empirical values ​​or obtained through experiments) data on the recovery rate of scrap steel and the cooling effect corresponding to the scrap steel, and then the cooling effect of the scrap steel can be calculated based on the relationship and a known amount of scrap steel recovery rate (the recovery rate is obtained according to the type of scrap steel).

[0072] It should be understood that for different types of scrap steel, the corresponding relationship between recovery rate and cooling effect is different, that is, α i The values ​​are not exactly the same.

[0073] Preferably, in step (1), the relationship between the yield and the cooling effect is:

[0074] β=α3η 3 +α2η 2 +α1η+α0

[0075] In the formula,

[0076] η is the scrap steel recovery rate;

[0077] β is the cooling effect of scrap steel, °C / t;

[0078] α i is the temperature coefficient, i=0, 1, 2 or 3.

[0079] It should be understood that α i Can be positive or negative.

[0080] Preferably, for several commonly used scrap steels, α3=0.00109; α2=-0.21334; α1=12.5-13.5; α0=-220 to -230.

[0081] Preferably, the calculation formula for the converter smelting waste heat temperature is constructed by the cooling temperature of the added coolant, the heating temperature of the heat generating agent, and the temperature change caused by the heat released by oxidation of the difference in silicon content between the silicon content in the molten iron and the silicon content in the standard molten iron.

[0082] The cooling temperature of the coolant, the heating temperature of the exothermic agent, and the temperature change caused by the heat released by oxidation of the difference in silicon content between the silicon content in the molten iron and the silicon content in the standard molten iron can be determined by those skilled in the art according to the specific smelting process. Among them, the temperature change caused by the heat released by oxidation of the difference in silicon content between the silicon content in the molten iron and the silicon content in the standard molten iron is considered because although the temperature of the molten iron is constant, the silicon content in the molten iron affects the temperature of the molten steel behind it, and the silicon is oxidized to release heat, thereby causing the temperature change.

[0083] In the present invention, a coolant refers to a material that undergoes a change as a whole to cool (i.e., absorb heat). A heat-generating agent refers to a material that undergoes a change as a whole to generate heat (i.e., emit heat).

[0084] The temperature change caused by the heat released by oxidation of the silicon content difference between the silicon content in the molten iron and the standard silicon content in the molten iron refers to the temperature change caused by the heat released by oxidation of the silicon content difference between the silicon content in the molten iron and the standard silicon content in the molten iron.

[0085] Preferably, the calculation formula for the converter smelting waste heat temperature is:

[0086]

[0087] In the formula,

[0088] ΔT=T e -T d

[0089] b=h×12.5

[0090] j is the type of coolant and exothermic agent added in addition to scrap steel;

[0091] W j is the amount of coolant and exothermic agent added in addition to scrap steel, t;

[0092] β j is the cooling effect or heating effect of the coolant or heating agent, ℃ / t;

[0093] h is oxygen consumption per ton of steel, m 3 / t;

[0094] b is the temperature correction coefficient, °C;

[0095] T Si is the temperature of the standard deviation of Si contained in molten iron, °C;

[0096] T e is the temperature of adding molten iron, ℃;

[0097] T d is the pouring furnace temperature, ℃.

[0098] More preferably, T Si =([Si] ％ -[Si0] ％ )×200

[0099] in,

[0100] [Si] ％ is the mass percentage of silicon in molten iron, %;

[0101] [Si0] ％ is the standard mass percentage of silicon in molten iron, which is 0.4%.

[0102] T Si Where 200 is the temperature change that can be brought about by a 1% [Si] content in molten iron in one embodiment, in °C.

[0103] In the present invention, the coolant and the exothermic agent can be any reagent that plays a corresponding role in the art. For example, the coolant is added lime, magnesium balls, light-burned dolomite, etc.; the exothermic agent is silicon carbon balls and / or graphite balls, etc.

[0104] It should be understood that β j is known and can be an empirical value or obtained through experiments.

[0105] The pouring temperature T d It refers to the temperature of the first pouring of the converter.

[0106] Those skilled in the art can calculate b or the furnace pouring temperature T according to the actual situation of converter smelting. d , as long as it is conducive to obtaining a suitable converter smelting waste heat temperature.

[0107] In a preferred embodiment of the present invention, the calculation formula of the above converter smelting waste heat temperature is:

[0108]

[0109] In the above specific calculation formula,

[0110] W1 is the weight of the heat-generating silicon-carbon ball, t;

[0111] W2 is the weight of lime, t;

[0112] W3 is the weight of light-burned dolomite and magnesium balls, t;

[0113] 200 refers to the temperature of silicon oxidation in molten iron, °C;

[0114] 687 is empirical data, calculated based on oxygen consumption per ton of steel × 12.5.

[0115] 35, 15, and 8 are the corresponding W j The effect of adding 1 ton on the molten pool temperature, that is, the cooling effect of 1 ton.

[0116] Preferably, the model equation is:

[0117]

[0118] In the formula,

[0119] i is the type of scrap steel;

[0120] a i The proportions of different types of scrap steel to be added;

[0121] β i is the cooling effect corresponding to different types of scrap steel, ℃ / t;

[0122] W scrap is the total amount of scrap steel loaded, t.

[0123] In the above model equation, the inventors of the present invention constructed the above equation based on the heat balance of scrap steel, flux materials (such as coolants, heat-generating agents) and the deviation of Si from the standard content in molten iron, according to the fact that the temperature that can be cooled by adding different types of scrap steel is equal to the temperature of the residual heat of converter smelting, combined with the temperature that can be cooled by adding different types of scrap steel and the total amount of scrap steel charged, the proportion of different types of scrap steel added and their corresponding cooling effects. Among them, the temperature T that can be cooled by adding a single type of scrap steel is i Satisfaction: T i =a i β i W scrap The temperatures to which different types of scrap steel can be cooled are:

[0124] The above-mentioned model equation of the present invention can enable technical personnel in this field to combine heat balance and the market conditions of pig iron and scrap steel, and formulate different iron-steel ratio batching models for selecting scrap steel entering the converter under the premise that the molten iron conditions and some scrap steel conditions (such as scrap steel ratio, scrap steel type) remain unchanged, thereby maximizing the reduction of the iron-steel ratio.

[0125] Preferably, the relationship function is:

[0126] W sci =a i W scrap

[0127] Where W sci is the loading amount of different types of scrap steel, t.

[0128] In step (3) of the present invention, the types of scrap steel and the proportion of scrap steel added can be set by those skilled in the art based on existing values ​​or range values ​​to be optimized. For example, the proportion is continuously optimized through a sub-gun model. This is prior art and will not be described in detail here.

[0129] Preferably, in step (3), the selection of the type of scrap steel and the proportion of scrap steel added can be modified according to the scrap steel cost performance index.

[0130] The calculation formula of the scrap steel cost performance index is constructed based on the scrap steel recovery rate, price, cooling effect influence coefficient, safety and environmental protection coefficient, and pile specific gravity influence coefficient.

[0131] Preferably, the calculation formula of the scrap steel cost performance index is: cp =y÷η×γ×s×d

[0132] Where: F cp is the scrap steel cost performance index;

[0133] y is the price of scrap steel excluding tax;

[0134] η is the scrap steel recovery rate;

[0135] γ is the cooling effect coefficient;

[0136] s is the safety and environmental protection factor;

[0137] d is the influence coefficient of pile specific gravity.

[0138] Among them, the cooling effect influence coefficient is the ratio of the cooling effect of various types of scrap steel to heavy scrap (which can be an empirical value); the safety and environmental protection coefficient is the ratio of the total amount of smoke generated by various types of scrap steel entering the furnace (based on the smoke from the overflow of the furnace fire) to the amount of smoke generated by the same amount of steel bar briquettes. For example, the amount of smoke generated by adding one ton of industrial briquette scrap steel is compared with the amount of smoke generated by one ton of steel bar briquettes, which can be an empirical value; the bulk density influence coefficient is the ratio of the bulk density of various types of scrap steel to steel bar pelletizing (which can be an empirical value).

[0139] In a preferred specific implementation, the cost performance index ranking of several types of purchased scrap steel is shown in the following Table 1. The smaller the cost performance index, the higher the ranking, and the higher the cost performance.

[0140] Table 1 Statistical sample of typical scrap steel cost performance index

[0141]

[0142] It can be seen from Table 1 above that the cost-effectiveness index of purchased pig iron is the lowest. It can be used as a cooling agent and a heating material. It is the preferred material for reducing iron and iron-steel ratio.

[0143] According to a preferred embodiment of the present invention, the method further comprises:

[0144] (4) calculating the iron-steel ratio according to the types of scrap steel selected in step (3) and their addition ratios and the obtained addition amounts of different types of scrap steel;

[0145] (5) selecting multiple groups of initial data, each group of initial data including the type of scrap steel selected in step (3) and its addition ratio, and repeating step (4);

[0146] (6) Select the group with the lowest iron-steel ratio in step (5) as the batching solution.

[0147] In the above preferred embodiment of the present invention, the iron-steel ratio can be calculated based on the selected initial data, and then the initial data can be changed and the obtained iron-steel ratio can be compared to optimize the scrap steel batch composition.

[0148] It should be understood that the iron-steel ratio refers to the amount of molten iron divided by the amount of steel produced. The amount of steel produced is calculated based on the type of scrap steel, the proportion and amount of scrap steel added, and the calculation method is prior art and will not be repeated here.

[0149] In the present invention, the temperature is measured by collecting samples in the molten iron tank, according to the T of the steelmaking process technical operation specification B standard. d According to the above relationship between recovery rate and cooling effect, model equation and relationship function, the proportion and amount of scrap steel to be added are optimized to achieve the purpose of reducing the iron-steel ratio.

[0150] For example, in a specific embodiment, in the 130-ton converter of Ezhou Iron and Steel, the molten iron temperature is 1350°C, the mass percentage of silicon in the molten iron is 0.4%, and the heat-generating agent silicon-carbon balls are supplemented, first refer to Table 1 to determine the type and proportion of scrap steel, and combine the above-mentioned relationship between the yield and the cooling effect to calculate the cooling effect of different scrap steels. Then, based on the added molten iron and slag (i.e., silicon-carbon ball slag), as well as the above-mentioned model equations and relationship functions, 7 groups of scrap steel batching schemes are calculated, and the iron-steel ratio is calculated. The specific converter batching is shown in Table 2 below.

[0151] Table 2 Specific implementation of 7 groups of converter material sample table

[0152]

[0153] As can be seen from Table 2 above, the iron-steel ratio of the first group is the lowest, so the batching scheme of the first group is preferably adopted.

[0154] In the present invention, when adding scrap steel, the amount of scrap steel added to the molten iron tank can be determined first according to the total amount of scrap steel, and the other part can be added through the scrap steel barrel to prevent blockage.

[0155] The present invention will be described in more detail below with reference to the embodiments.

[0156] Example 1

[0157] Taking the production of HRB400 as an example, the molten iron temperature is 1350℃ and the Si mass percentage of the molten iron is 0.4%. The molten iron tank is added with 9 tons of scrap steel and blast furnace gas is used to bake the scrap steel in the molten iron tank to increase the scrap steel temperature to 750℃. Then 119t of molten iron containing 9 tons of scrap steel is added. According to empirical values, the pouring furnace temperature is known to be 1640℃. According to the cost-effectiveness ranking of scrap steel in Table 1 and the actual situation of the factory, the types of scrap steel selected are pig iron (92% recovery rate), heavy scrap (94% recovery rate), steel bar briquettes (94% recovery rate), wood shavings briquettes (91% recovery rate), industrial briquettes (88% recovery rate), and recycled scrap steel (35% recovery rate, referring to the scrap steel generated in the company's production process, specifically structural frames and scrapped equipment) as scrap steel ingredients. The proportion of scrap steel structure is determined according to cost-effectiveness and actual production. The factory ratio is 15:12:12:1:3:2, 4.5t of lime is added, 1.9t of silicon manganese balls are added, and 1.5 tons of magnesium balls are added. The total amount of scrap steel added, the amount of each type added, and the iron-steel ratio are calculated as follows:

[0158] first step,

[0159] Based on the previous experience data, the recovery rate and cooling effect of different types of scrap steel are constructed

[0160] β=α3η 3 +α2η 2 +α1η+α0;

[0161] After fitting, the relationship between the recovery rate and cooling effect of different scrap steels in this embodiment is as follows:

[0162] For heavy scrap (rebar briquettes), the recovery rate is calculated at 94%, α1=12.9; α0=-223; α3=0.00109; α2=-0.21332, and β=10.

[0163] For industrial briquetting, the yield is 88%, α1=13; α0=-223; α3=0.00109; α2=-0.21332, and β=12.

[0164] For wood shavings briquetting, the yield is 91%, α1=13; α0=-223; α3=0.00109; α2=-0.21332, and β=15.

[0165] For pig iron blocks, with a yield of 92%, α1=12.9; α0=-225; α3=0.00109; α2=-0.21332, and β=5.

[0166] For the recycling of scrap steel, the recovery rate is 35%, α1=13.2; α0=-227; α3=0.00109; α2=-0.21332, and β=20.

[0167] Step 2:

[0168] According to these scrap steel types and their corresponding cooling effect β obtained above, the model equation is: and W sci =a i W scrap ,

[0169] Calculate the amount of scrap steel added as follows:

[0170] W scrap =(T e -T d +([Si]-0.4%)×200+W 硅锰球 ×35-(W 石灰 ×8+W 镁球 ×15)+b)÷(α 生铁 ×5+α 钢筋压块 ×10+α 工业压块 ×12+α 刨花压块 ×15+α 重废 ×10+α 回收废钢 ×20)

[0171] =(1350℃-1640℃+(0.4-0.4)×200℃+1.9t×35℃ / t-(4.5t×8℃ / t+1.5t×15℃ / t)+687℃ )÷(1 / 3×5℃ / t+4 / 15×10℃ / t+4 / 15×12℃ / t+1 / 45×15℃ / t+3 / 45×10℃ / t+2 / 45×20℃ / t)

[0172] =405÷9.42=43(t).

[0173] From the above calculation formula, we can get W scrap is 43t. Then W is calculated according to the addition ratio sci . Thus, the batching scheme is obtained.

[0174] According to the amount of each scrap steel added and the total amount added, combined with the material balance, the steel output is calculated to be 150 tons, and the iron-steel ratio is calculated to be 733kg / t. It can be seen that the iron-steel ratio is low and the batching plan is feasible.

[0175] The batching scheme of this embodiment does not cause scrap steel to block the furnace during production.

[0176] The economic benefits of this embodiment are as follows: the output of molten iron in the first half of 2021 is 2.2433 million tons, and the iron-steel ratio is reduced from 820kg / t in 2020 to 762.1kg / t in the first half of 2021. It is expected that the output will increase by 207,900 tons, and the adjustment structure of scrap steel will reduce the cost by 10.56 million yuan compared with 2020. Among them, the batching method in 2020 is to blindly add a single type of existing scrap steel (rebar briquettes, industrial briquettes, heavy scrap or sheared materials). In this traditional method, the amount of scrap steel selected blindly according to experience is prone to blockage of the furnace mouth, and the iron-steel ratio control is unstable.

[0177] Example 2

[0178] Taking the production of HRB400 as an example, the temperature of the molten iron is 1350℃, and the mass percentage of Si in the molten iron is 0.4%. The molten iron tank is added with 9 tons of scrap steel, and blast furnace gas is used to bake the scrap steel in the molten iron tank to increase the temperature of the scrap steel to 750℃, and then 119t of molten iron containing 9 tons of scrap steel is added. According to empirical values, the pouring temperature is known to be 1640℃. According to the cost-effectiveness ranking of scrap steel in Table 1 and the actual situation in the factory, only steel briquettes (94% recovery rate) are selected as the scrap steel ingredient variety, 4.5t of lime is added, and 1.5 tons of magnesium balls are added. There is no need to supplement external heat, and the molten iron in the converter furnace forms a critical heat balance with scrap steel and flux. The total amount of scrap steel added, the amount of each type added, and the iron-steel ratio are calculated as follows:

[0179] first step,

[0180] According to the previous empirical data, the recovery rate and cooling effect β=α3η corresponding to different types of scrap steel are constructed 3 +α2η 2 +α1η+α0

[0181] For steel bar blocks, the yield rate is 94%, α1 = 12.9; α0 = -223; α3 = 0.00109; α2 = -0.21332, and the cooling effect β = 10.

[0182] Step 2:

[0183] According to these scrap steel types and their corresponding cooling effect β obtained above, the model equation is: and W sci =a i W scrap ,

[0184] Calculate the amount of scrap steel added as follows:

[0185] W scrap =(T e -T d +([Si]-0.4%)×200-(W 石灰 ×8+W 镁球×15)+b)÷(α 钢筋压块 ×10)

[0186] =(1350℃-1640℃+(0.4-0.4)×200℃-(4.5t×8℃ / t+1.5t×15℃ / t)+687℃)÷(1×10℃ / t)

[0187] =338÷10=33.8(t).

[0188] Then calculate W according to the addition ratio sci . Thus, the batching scheme is obtained.

[0189] According to the amount of each scrap steel added and the total amount added, combined with the material balance, the steel output is calculated to be 150 tons, and the iron-steel ratio is calculated to be 841.3kg / t.

[0190] In this embodiment, there is no furnace blocking due to scrap steel.

[0191] This embodiment organizes production without increasing the cost of heating agent and pig iron under the conditions of insufficient molten iron, shrinking steel market and unstable raw materials, and can still produce smoothly.

[0192] It can be seen from the above embodiments that the embodiments of the present invention adopt the above specific method to reasonably mix materials. No matter whether a mixed material or a single material is selected, it will not cause blockage of the furnace mouth and can carry out smooth production. In addition, the economic benefits are more significant by adopting a low iron-steel ratio solution.

Claims

1. A method for batching scrap steel for converter smelting, characterized in that: The following steps are involved: (1) Based on the scrap steel recovery rate and the cooling effect corresponding to the scrap steel, the relationship between the recovery rate and the cooling effect corresponding to different types of scrap steel is constructed; (2) Construct model equations for the converter smelting waste heat temperature, scrap steel addition ratio and its corresponding cooling effect, and the total amount of scrap steel added, and construct the relationship function between the addition amount of different types of scrap steel and the total amount of scrap steel added; (3) selecting the type of scrap steel and its addition ratio, and obtaining the cooling effect corresponding to the type of scrap steel by using the relationship between the recovery rate and the cooling effect according to the recovery rate corresponding to the type of scrap steel; then obtaining the total amount of scrap steel added by using the model equation according to the cooling effect and addition ratio corresponding to the scrap steel, and the converter smelting waste heat temperature, and obtaining the addition amount of different types of scrap steel by using the relationship function; In step (1), the relationship between the yield and the cooling effect is: In the formula, η is the scrap steel recovery rate; β is the cooling effect of scrap steel, °C / t; α i is the temperature coefficient, i=0, 1, 2 or 3; The model equation is: In the formula, W scrap is the total loading amount of scrap steel, t; ∆T is the value of the temperature of adding molten iron minus the pouring temperature, ℃; W j is the amount of coolant and exothermic agent added in addition to scrap steel, t; β j is the cooling effect or heating effect of the coolant or heating agent, ℃ / t; b is the temperature correction coefficient, °C; T Si is the temperature of the standard deviation of Si contained in molten iron, °C; i is the type of scrap steel; a i The proportions of different types of scrap steel to be added; β i is the cooling effect corresponding to different types of scrap steel, ℃ / t; The relationship function is: ; Where W sci is the loading amount of different types of scrap steel, t.

2. The method for batching scrap steel for converter smelting according to claim 1, wherein: α3=0.00109; α2=-0.21334; the value range of α1 is 12.5-13.5; the value range of α0 is -220 to -230.

3. The method for batching scrap steel for converter smelting according to claim 1, wherein: The calculation formula of the converter smelting waste heat temperature is constructed by the cooling temperature of the added coolant, the heating temperature of the exothermic agent, and the temperature change caused by the heat released by oxidation of the silicon content difference between the silicon content in the molten iron and the silicon content in the standard molten iron.

4. The method for batching scrap steel for converter smelting according to claim 3, wherein: The converter smelting waste heat temperature calculation formula is: In the formula, j is the type of coolant and exothermic agent added in addition to scrap steel; W j is the amount of coolant and exothermic agent added in addition to scrap steel, t; β j is the cooling effect or heating effect of the coolant or heating agent, ℃ / t; h is oxygen consumption per ton of steel, m 3 / t; T Si is the temperature of the standard deviation of Si contained in molten iron, °C.

5. The method for batching scrap steel for converter smelting according to claim 4, wherein: in, [Si] % is the mass percentage of silicon in molten iron, %; [Si0] % is the standard mass percentage of silicon in molten iron, %.

6. The method for batching scrap steel for converter smelting according to claim 1, wherein: In step (3), the selection of the type of scrap steel and its addition ratio is modified according to the scrap steel cost performance index, and the calculation formula of the scrap steel cost performance index is: Where: F cp is the scrap steel cost performance index; y is the price of scrap steel excluding tax; ŋ is the scrap steel recovery rate; γ is the cooling effect coefficient; s is the safety and environmental protection factor; d is the influence coefficient of pile specific gravity.

7. The method for batching scrap steel for converter smelting according to claim 1, wherein: The method further includes: (4) calculating the iron-steel ratio according to the types of scrap steel selected in step (3) and their addition ratios and the obtained addition amounts of different types of scrap steel; (5) selecting multiple sets of initial data, each set of initial data including the type of scrap steel selected in step (3) and its addition ratio, and repeating step (4); (6) Select the group with the lowest iron-steel ratio in step (5) as the batching solution.

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