Converter smelting method for dynamically adding high silicon iron blocks to partially replace silicon iron alloy

Abstract

The present invention discloses a converter smelting method for dynamically adding high silicon iron blocks to partially replace silicon iron alloys. According to the composition standard of the smelting steel grade and the final composition of the smelting molten steel, the phosphorus content of the molten steel is ensured to be within a reasonable range, and the amount of high silicon iron blocks added is dynamically adjusted to replace part of the silicon iron alloy. When the converter is tapping steel, the method achieves the goal of replacing part of the silicon iron alloy material for alloying through the appropriate addition method and amount of high silicon iron blocks; and compared with directly adding high silicon iron blocks to the converter, the ladle addition yield is higher, and the yield is close to 100%; and if the high silicon iron blocks are added to the converter, the carbon, silicon, and phosphorus are almost completely oxidized, and the total blow loss is 20%; so the change of this method increases the yield by 20%. This method greatly reduces the consumption of silicon iron alloys; it can further reduce the cost of alloy use, improve the utilization rate of high silicon iron blocks, and achieve the goal of reducing production costs and increasing efficiency.

Description

Technical Field

[0001] The invention relates to a smelting technology, in particular to a converter smelting method for dynamically adding high-silicon iron blocks to partially replace ferrosilicon alloy. Background Art

[0002] The use of new alloy substitutes and ensuring that other components do not exceed the reasonable range, thereby achieving the requirement of reducing the cost of alloy materials is a problem currently faced. According to the characteristics of some existing production materials, the use of new alloy materials and the formulation of reasonable addition rules are extremely feasible solutions in production. Therefore, whether it is possible to utilize the high silicon characteristics of high silicon iron blocks used in production and avoid the high phosphorus shortcomings, formulate a set of addition rules based on molten steel composition, steel grade composition standards, and phosphorus content changes, and use it as a new alloy material has become a research direction with high practical value. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a converter smelting method for dynamically adding high-silicon iron blocks to partially replace ferrosilicon alloy.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: based on the composition standard of smelting steel grades and the final composition of smelting molten steel, the phosphorus content of molten steel is ensured to be within a reasonable range, and the amount of high silicon iron blocks added is dynamically adjusted to replace part of the ferrosilicon alloy; the ferrosilicon alloy nuclear reduction and the amount of high silicon iron blocks added are calculated using the following formulas (1)-(3);

[0005]

[0006] in,

[0007]

[0008] but,

[0009]

[0010] Where:

[0011] M 高硅铁块 —Amount of high silicon iron block added, kg;

[0012] M 出钢量 —Steel output, kg;

[0013] M Si-Fe核 —Nuclear reduction of ferrosilicon alloy, kg;

[0014] ω[Si] 判 —The lower limit of silicon content in the steel, wt%;

[0015] ω[Si] 终—Silicon content in steel at the end of converter smelting, wt%;

[0016] ω[P] 内 —Internal control requirements for P content in molten steel after adding high silicon iron blocks, wt%;

[0017] ω[P] 终 —P content in steel at the end of converter smelting, wt%;

[0018] ω[P] 判 — Upper limit of determination of P content in smelting steel, wt%;

[0019] ω[Si] Si-Fe —Silicon content of ferrosilicon alloy added during converter steelmaking, wt%;

[0020] η Si1 —Silicon-ferrosilicon alloy yield, %;

[0021] η Si2 -High ferrosilicon block recovery rate, %;

[0022] ω[Si] 高硅铁块 —Silicon content of high silicon iron block, wt%;

[0023] ω[P] 高硅铁块 —P content of high silicon iron block, wt%.

[0024] Furthermore, corresponding high-silicon iron blocks are added on the premise of meeting the internal control requirements for P content, and then the composition meets the standards by adding ferrosilicon alloy.

[0025] The beneficial effect of the above technical scheme is that: when the converter is tapped, the method of the present invention can achieve the goal of replacing part of the ferrosilicon alloy material for alloying by adding high silicon iron blocks in a suitable manner and amount; and compared with directly adding high silicon iron blocks to the converter, the ladle addition yield is higher, and the yield is close to 100%; if the high silicon iron blocks are added to the converter, the carbon, silicon and phosphorus are almost completely oxidized, and the total blow loss is 20%; so the change of the adding method of the present invention increases the yield by 20%. The actual effect of the present invention also shows that: based on the silicon content of the high silicon iron blocks being 16.3% and the silicon content of the ferrosilicon alloy being 75%, using 100kg of high silicon iron blocks per furnace can save 100*16.3% / 75%=21.7kg of ferrosilicon, greatly reducing the consumption of ferrosilicon alloy; in addition, the Fe% in the high silicon iron blocks is above 80wt%, and each 100kg used can theoretically increase the amount of molten steel by 80kg. The present invention can further reduce the use cost of the alloy, improve the utilization rate of high-ferrosilicon blocks, and achieve the goal of reducing production costs and increasing efficiency. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with specific implementation modes.

[0027] The converter smelting method of dynamically adding high silicon iron blocks to partially replace ferrosilicon alloy is as follows: during the converter steelmaking process, a certain amount of high silicon iron blocks are added to the ladle to replace part of the ferrosilicon alloy; before the start of smelting, a suitable amount of high silicon iron blocks are loaded into the silo in advance for standby; after the smelting is completed, the discharge amount of high silicon iron blocks is set according to the final molten steel composition results and the determined reduction amount; and they are added to the ladle in a timely manner to ensure that the molten steel composition meets the requirements. The process steps are as follows:

[0028] 1. Prepare ingredients:

[0029] The high silicon iron block is put into the alloy silo or packed for use. The physical and chemical indicators of the added high silicon iron block are shown in Table 1.

[0030] Table 1: Physical and chemical indicators of high silicon iron block

[0031] C / wt% Si / wt% P / wt% S / wt% Particle size / mm TFe / wt% 0.50～0.60 15～20 0.45～0.50 0.0040～0.0045 5～120 ≥80

[0032] 2. High silicon iron block addition amount and silicon iron core reduction amount:

[0033] On the premise of meeting the internal control requirements for P content, the corresponding high-silicon iron blocks are added, and then the composition is brought up to standard by adding ferrosilicon alloys, that is, all the ferrosilicon alloys reduced in the smelting steel grade are replaced by high-silicon iron blocks, and the composition meets the standard and the P content meets the internal control requirements, then all of them can be replaced; wherein, the internal control requirements for P content are standards established based on the composition of molten steel at the end of smelting and the composition standards of smelting steel grades; if it is calculated that all replacements cause the P content to exceed the internal control requirements for the P content of the steel grade being smelted, then on the premise of meeting the internal control standards for P content, the corresponding high-silicon iron blocks are added, and then the composition is brought up to standard by adding ferrosilicon alloys.

[0034] According to the composition requirements of different steel grades and the composition of molten steel at the end of smelting, the corresponding alloy material reduction and high silicon iron block feed amount of different smelting steel grades are determined, and the following formulas (1), (2) and (3) are used for calculation:

[0035]

[0036] in,

[0037]

[0038] but,

[0039]

[0040] Where:

[0041] M 高硅铁块 —Amount of high silicon iron block added, kg;

[0042] M 出钢量 —Steel output, kg;

[0043] M Si-Fe核 —Nuclear reduction of ferrosilicon alloy, kg;

[0044] ω[Si] 判 —The lower limit of silicon content in the steel, wt%;

[0045] ω[Si] 终 —Silicon content in steel at the end of converter smelting, wt%;

[0046] ω[P] 内 —Internal control requirements for P content in molten steel after adding high silicon iron blocks, wt%;

[0047] ω[P] 终 —P content in steel at the end of converter smelting, wt%;

[0048] ω[P] 判 — Upper limit of determination of P content in smelting steel, wt%;

[0049] ω[Si] Si-Fe —Silicon content of ferrosilicon alloy added during converter steelmaking, wt%;

[0050] η Si1 —Silicon-ferrosilicon alloy yield, %;

[0051] η Si2 -High ferrosilicon block recovery rate, %;

[0052] ω[Si] 高硅铁块 —Silicon content of high silicon iron block, wt%;

[0053] ω[P] 高硅铁块 —P content of high silicon iron block, wt%.

[0054] 3. Smelting experiment:

[0055] 3.1. According to the on-site production experience, the ferrosilicon recovery rate is 90%, so η can be set Si1 =90%, the recovery rate of high silicon iron block is close to 100%, so η is set Si2 =95%; Taking a certain furnace smelting of Q355C (Nb) as an example, the phosphorus content judgment standard is 0.03wt%, the final molten steel phosphorus content is 0.025wt%, the output is about 112 tons, and the composition of the batch of ferrosilicon alloy and high silicon iron blocks used for the experiment is shown in Table 2.

[0056] Table 2: Alloy composition information

[0057] Ingredient content / wt% C Si P S Al Ferrosilicon 0.06 73 0.02 0.004 - High silicon iron block 0.56 16.3 0.46 0.0043 -

[0058] 3.2 Substitute them into formulas (1) to (3) respectively, and the calculation process of the amount of high silicon iron block added is as follows:

[0059] but

[0060] ω[P] 内 =0.0255wt%;

[0061] but

[0062] M 高硅铁块 =121.7kg;

[0063] but

[0064] M Si-Fe核 =28.7kg.

[0065] 3.3. The nominal capacity of the experimental converter is 120t, and the steel output is about 112t, so the steel output is set to 112t; the alloy core reduction and the amount of high silicon iron block added for different steel grades are determined, and the high silicon iron block is added using the above scheme; the smelting steel grades are HRB-400W and Q355C (Nb), and the smelting results are shown in Tables 3 and 4.

[0066] Table 3: Results of smelting steel grade HRB-400W

[0067] Furnace No. Ferrosilicon / kg High silicon iron block dosage / kg Si / wt% 20807022 674 405 0.452 20807023 640 545 0.467 20807056 657 472 0.442 20807057 686 354 0.458 20807058 670 425 0.463

[0068] Table 3 shows that the steel grade is HRB-400W, and the average amount of ferrosilicon added is 313.6 kg / furnace, so ferrosilicon alloy is saved by 77.8 kg / furnace, and the silicon content of the composition meets the standard. Due to the influence of factors such as the alloy material, the composition of high-silicon ferrosilicon blocks and the amount of addition, there is a certain error between the experimental results and the theoretical calculation results, but they are basically consistent.

[0069] Table 4: Smelting results of Q355C (Nb)

[0070] Furnace No. Ferrosilicon / kg High silicon iron block dosage / kg End point Si / wt% 20706035 313 120 0.201 20706036 305 165 0.219 20706037 319 95 0.221 20706052 312 145 0.202 20706053 330 47 0.225

[0071] As can be seen from Table 4, the smelting steel grade is Q355C (Nb), the average addition amount of high silicon iron block is 114.4kg / furnace, and the theoretical saving of ferrosilicon alloy is 27kg / furnace. Due to the influence of factors such as alloy material, high silicon iron block composition, and fluctuations in experimental addition amount, there is a certain deviation between the experimental results and the theoretical calculation results, but they are basically consistent.

[0072] Example 1: The converter smelting method of dynamically adding high-silicon iron blocks to partially replace ferrosilicon alloy is specifically described as follows.

[0073] According to the above calculation scheme, 112 tons of molten steel were tapped from the converter to smelt HRB-400W steel. The silicon content of the furnace was 0.0025%, the phosphorus content was 0.025%, 472 kg of high silicon iron blocks were added, 655 kg of ferrosilicon were added, and 111.2 kg of ferrosilicon alloy was reduced. According to the standard of 472 kg / furnace, high silicon iron blocks were added to the ladle. 475 kg of high silicon iron blocks were actually added. The tapping time was 285 seconds, and the final silicon content was 0.46%. After testing, the obtained molten steel met the requirements of HRB-400W steel. The calculation process is as follows:

[0074] but

[0075] ω[P] 内 =0.027wt%;

[0076] but

[0077] M 高硅铁块 =471.6kg;

[0078] but

[0079] M Si-Fe核 =111.2kg.

[0080] Example 2: The converter smelting method of dynamically adding high-silicon iron blocks to partially replace ferrosilicon alloy is specifically described as follows.

[0081] Smelting Q355C (Nb) steel, 112t molten steel was tapped from the converter. According to the above calculation scheme, the silicon content of the furnace was 0.0015%, the phosphorus content was 0.025%, 118kg of high silicon iron blocks were added, 313kg of ferrosilicon was added, and 27.8kg of ferrosilicon alloy was reduced. During the tapping process, high silicon iron blocks were continuously added to the ladle at a standard of 118kg / furnace. 122kg of high silicon iron blocks were actually added, the tapping time was 278s, and the final silicon content was 0.22%. After testing, the obtained molten steel met the requirements of Q355C (Nb). The calculation process is as follows:

[0082] but

[0083] ω[P] 内 =0.0255wt%;

[0084] but

[0085] M 高硅铁块 =117.9kg;

[0086] but

[0087] M Si-Fe核=27.8kg。

Claims

1. A converter smelting method for dynamically adding high-silicon iron blocks to partially replace ferrosilicon alloy, characterized in that: Based on the composition standards of smelting steel grades and the final composition of smelting molten steel, the amount of high-silicon iron blocks added is dynamically adjusted to replace part of the ferrosilicon alloy. The reduction of ferrosilicon alloy and the amount of high-silicon iron blocks added are calculated using the following formulas (1)-(3); in, but, Where: M 高硅铁块 —Amount of high silicon iron block added, kg; M 出钢量 —Steel output, kg; M Si-Fe核 —Nuclear reduction of ferrosilicon alloy, kg; ω[Si] 判 —The lower limit of silicon content in the steel, wt%; ω[Si] 终 —Silicon content in steel at the end of converter smelting, wt%; ω[P] 内 —Internal control requirements for P content in molten steel after adding high silicon iron blocks, wt%; ω[P] 终 —P content in steel at the end of converter smelting, wt%; ω[P] 判 — Upper limit of determination of P content in smelting steel, wt%; ω[Si] Si-Fe —Silicon content of ferrosilicon alloy added during converter steelmaking, wt%; η Si1 —Silicon-ferrosilicon alloy yield, %; η Si2 -High ferrosilicon block recovery rate, %; ω[Si] 高硅铁块 —Silicon content of high silicon iron block, wt%; ω[P] 高硅铁块 —P content of high silicon iron block, wt%.

2. The converter smelting method of dynamically adding high silicon iron blocks to partially replace ferrosilicon alloy according to claim 1, characterized in that: On the premise of meeting the internal control requirements for P content, add the corresponding high-silicon iron blocks, and then add ferrosilicon alloy to make the composition meet the standards.

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