Converter steelmaking process using iron-containing cold charge

Abstract

The invention relates to a converter steelmaking process using iron-containing cold charge, and belongs to the technical field of converter steelmaking. Auxiliary materials are prepared according to the content of the silicon element in the molten iron and the iron recovery rate of the cold pressing balls in the iron-containing cold charge, and the auxiliary materials comprise a magnesium slagging material, a lime slagging material and the iron-containing cold charge; bedding materials are laid after slag splashing of the converter is completed; scrap steel is added into the converter, and molten iron is added; lowering the oxygen lance from the initial position to a to-be-blown point, and starting blowing and charging; continuously blowing and feeding; and after blowing to a smelting end point, lifting a gun to an initial position, carrying out tapping operation, carrying out deslagging after tapping is finished, and adopting slag remaining operation with the slag remaining amount being 1 / 3-1 / 2 of the slag amount. The dynamic conditions of the molten pool are improved, so that metal elements in the iron-containing cold charge can enter the molten pool more easily, the recovery amount of the iron-containing cold charge is increased, the tapping amount is increased, and finally the steel material consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of converter steelmaking, and in particular to a converter steelmaking process utilizing iron-containing cold material. Background Art

[0002] Steel slag is the main solid waste in the steelmaking process, accounting for about 15% to 20% of steel production. Affected by the oxidizing property at the end of blowing, steel slag contains a certain amount of metallic iron and iron oxides. The coarse dust and fine dust produced by dry dust removal in the steelmaking process, and the iron oxide scale produced in the continuous casting-rolling process of the steelmaking plant contain a large amount of TFe. If not utilized, it will cause metal loss.

[0003] In recent years, the recovery of elements from solid waste has become an important direction for energy conservation and emission reduction in converter steelmaking. Solid waste containing iron elements generated during the steelmaking process, such as dust, steel slag, and iron oxide, can be recycled through slagging to promote the in-plant circulation of metal elements, reduce smelting costs, and help increase the recovery volume of the steelmaking process and reduce the emission of metal waste.

[0004] Steel mills usually use iron-containing cold materials such as pellets, sintered ore, and lump ore as coolants to recycle the excess heat in the steelmaking process, which not only cools the molten pool but also recycles the metallic iron in it. The recycling process of iron-containing cold materials slag making is as follows: the cold material melts in the slag → the iron oxide diffuses from the slag side to the slag-metal interface → the interface chemical reaction → the generated metallic iron diffuses to the metal-slag interface. The limiting link is the diffusion of iron oxide to the slag-metal interface.

[0005] In order to increase the metal recovery rate of ferrous cold materials, it is necessary to find a method to improve the dynamic conditions of the molten pool, that is, to control the smelting by coordinating the feeding and top and bottom blowing intensities, and provide technical support for the recovery of metal elements in the ferrous cold materials into the molten pool, so as to increase the steel output, reduce metal emissions, and thus reduce steel material consumption ((molten iron + scrap steel loading) / steel output). Summary of the invention

[0006] In view of the above analysis, the present invention aims to provide a converter steelmaking process using iron-containing cold material, thereby increasing the recovery of iron-containing cold material and reducing steel material consumption.

[0007] In one aspect, the present invention provides a converter steelmaking process using iron-containing cold material, comprising the following steps:

[0008] S1: preparing auxiliary materials according to the silicon content in molten iron and the iron recovery rate of cold-pressed balls in the iron-containing cold material, wherein the auxiliary materials include magnesium slag-making material, lime slag-making material and iron-containing cold material;

[0009] After the slag splashing of the converter is completed, 90% to 100% of the total amount of magnesium slag-making material, 30% to 40% of the total amount of lime slag-making material and 30% to 50% of the total amount of iron-containing cold material are added in sequence to form the bottom material;

[0010] S2: adding scrap steel and molten iron into the converter;

[0011] S3: lower the oxygen lance from the starting position to the blowing point and start blowing;

[0012] S4: After blowing for a period of time, start adding materials, and add 50% to 70% of the total amount of iron-containing cold materials, 30% to 40% of the total amount of lime slag materials, and the remaining magnesium slag materials in sequence;

[0013] S5: Continue blowing and add the remaining lime-based slag-making material;

[0014] S6: After blowing to the end of smelting, lift the gun to the starting position and perform the tapping operation. After the tapping is completed, slag is poured and the slag retention operation is adopted. The slag retention amount is 1 / 3 to 1 / 2 of the slag amount.

[0015] S7: Lower the oxygen gun from the starting position to the blowing point, and use nitrogen to perform slag splashing operation. The slag splashing time is 3 to 5 minutes. After the slag splashing is completed, lay the base material.

[0016] Furthermore, the iron-containing cold material is one or more of cold-pressed balls, sintered ore, pelletized ore and lump ore.

[0017] Furthermore, the composition requirements of the cold-pressed balls are that the TFe content is ≥45%, the compressive strength of the cold-pressed balls is ≥1400N, and the water content is <3%; the iron recovery rate of the cold-pressed balls is greater than 30%, and the calculation formula of the iron recovery rate is as follows:

[0018]

[0019] Furthermore, the cold pressed balls are dedusted coarse ash, dedusted fine ash, iron oxide scale and steel slag magnetic separation powder.

[0020] Furthermore, the iron recovery rate of cold pressed balls is 30% <R Fe <60%;

[0021] When Si in molten iron is less than 0.20wt%, the auxiliary materials include 40% iron-containing cold material, 10% magnesium slag material, and 25% and 25% lime slag material, respectively, in terms of mass percentage;

[0022] When 0.20wt%≤Si<0.50wt% in molten iron, the auxiliary materials include 33-36% iron-containing cold material, 10-13% magnesium slag material, and 20-27% and 26-33% lime slag material, respectively, in terms of mass percentage;

[0023] When 0.50wt%≤Si<0.80wt% in molten iron, the auxiliary materials include 23-27% iron-containing cold material, 11-12% magnesium slag-making material, and 9-11% and 49-56% lime and limestone slag-making materials, respectively, in terms of mass percentage.

[0024] Furthermore, the iron recovery rate of cold pressed balls R Fe >60%;

[0025] When Si in molten iron is less than 0.20wt%, the auxiliary materials include 40% iron-containing cold material, 30% magnesium slag material, and 30% lime and 0% limestone slag materials, respectively, in terms of mass percentage.

[0026] When 0.20wt%≤Si<0.50wt% in molten iron, the auxiliary materials include 40-50% iron-containing cold material, 22-30% magnesium slag material, and 20-27% and 0-10% lime and limestone slag materials, respectively, in terms of mass percentage;

[0027] When 0.50wt%≤Si<0.80wt% in molten iron, the auxiliary materials include 35-38% iron-containing cold material, 17-18% magnesium slag-making material, and 20-24% and 10-27% lime and limestone slag-making materials, respectively, in terms of mass percentage.

[0028] Furthermore, in step S3, oxygen is blown with the oxygen lance throughout the entire process, the top blowing lance position in the early stage of smelting is 1.3-1.5m, the top blowing lance position in the middle stage of smelting is 1.4-1.5m, the top blowing lance position in the late stage of smelting is 1.4-1.6m, and the top blowing lance position at the end of smelting is 1.1-1.3m.

[0029] Furthermore, in step S3, the top blowing intensity in the early stage of smelting is 3.4-3.9 Nm 3 / (min·t -1 ), the top blowing intensity in the middle stage of smelting is 3.5~4.1Nm 3 / (min·t -1 ), the top blowing intensity in the later stage of smelting is 3.6~4.2Nm 3 / (min·t -1 ), the top blowing intensity at the end of blowing is 3.7~4.2Nm 3 / (min·t -1 ).

[0030] Furthermore, in step S3, the bottom blowing intensity in the early stage of smelting is 0.06-0.08Nm 3 / (min·t- 1 ), the bottom blowing intensity in the middle stage of smelting is 0.02~0.04Nm3 / (min·t -1 ), the bottom blowing intensity in the later stage of smelting is 0.05~0.06Nm 3 / (min·t -1 ), stir for 1 to 3 minutes after blowing, and the bottom blowing intensity is 0.04 to 0.06 Nm 3 / (min·t -1 ).

[0031] Furthermore, the magnesia slag-making material comprises one or more of magnesium balls, dolomite, and raw dolomite.

[0032] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0033] 1. In the present invention, magnesium slag-making material, lime slag-making material and iron-containing cold material are added into the converter in a multiple addition manner for blowing at different stages, and the process of blowing is controlled to improve the dynamic conditions of the molten pool, so that the metal elements in the iron-containing cold material can more easily enter the molten pool, thereby increasing the recovery of the iron-containing cold material, thereby increasing the steel output, and finally reducing the consumption of steel materials;

[0034] 2. In the present invention, the iron-containing cold material is a cold-pressed ball, which requires TFe content ≥45%, compressive strength ≥1400N, and water content <3%; and the iron recovery rate RFe is calculated, which requires RFe>30%, which can increase the recovery of the iron-containing cold material.

[0035] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be achieved and obtained through the contents particularly pointed out in the description. DETAILED DESCRIPTION

[0036] Steel slag is produced during the steelmaking process. It is the main solid waste and contains a certain amount of metallic iron and iron oxides. The TFe content is relatively high. If it is not utilized, it will cause metal loss.

[0037] In order to reduce the loss of metal, steel slag is recycled and reused to reduce the discharge of metal waste. The recycling process of slag-making of iron-containing cold material is as follows: the cold material melts in the slag → the iron oxide diffuses from the slag side to the slag-metal interface → the interface chemical reaction → the generated metallic iron diffuses to the metal-slag interface. The limiting link is the diffusion of iron oxide to the slag-metal interface.

[0038] In order to increase the recovery amount and steel output of iron-containing cold materials and ultimately reduce the consumption of steel materials, the present invention provides a converter steelmaking process using iron-containing cold materials, comprising the following steps:

[0039] S1: preparing auxiliary materials according to the silicon content in molten iron and the iron recovery rate of cold-pressed balls in the iron-containing cold material, wherein the auxiliary materials include magnesium slag-making material, lime slag-making material and iron-containing cold material;

[0040] After the slag splashing of the converter is completed, 90% to 100% of the total amount of magnesium slag-making material, 30% to 40% of the total amount of lime slag-making material and 30% to 50% of the total amount of iron-containing cold material are added in sequence to form the bottom material;

[0041] S2: adding scrap steel and molten iron into the converter;

[0042] S3: lower the oxygen lance from the starting position to the blowing point and start blowing;

[0043] S4: After blowing for a period of time, start adding materials, and add 50% to 70% of the total amount of iron-containing cold materials, 30% to 40% of the total amount of lime slag materials, and the remaining magnesium slag materials in sequence;

[0044] S5: Continue blowing and add the remaining lime-based slag-making material;

[0045] S6: After blowing to the end of smelting, lift the gun to the starting position and perform the tapping operation. After the tapping is completed, slag is poured and the slag retention operation is adopted. The slag retention amount is 1 / 3 to 1 / 2 of the slag amount.

[0046] S7: Lower the oxygen gun from the starting position to the blowing point, and use nitrogen to perform slag splashing operation. The slag splashing time is 3 to 5 minutes. After the slag splashing is completed, lay the base material.

[0047] Compared with the prior art, the furnace steelmaking process provided by the present invention adopts a multiple addition method to add magnesium slag-making material, lime slag-making material and iron-containing cold material into the converter for blowing at different stages, and controls the process of the blowing process to improve the kinetic conditions of the molten pool, so that the metal elements in the iron-containing cold material can more easily enter the molten pool, thereby increasing the recovery amount of the iron-containing cold material and reducing the consumption of steel materials.

[0048] It should be noted that when performing steelmaking in a heat, steps S1 to S7 of the present invention form a cycle, and in step S7, after slag splashing is completed, charging is performed again, which is to repeat the operation in step S1. When performing a single heat or executing the last heat, no further charging is required after step S5, and steelmaking is completed.

[0049] Specifically, the iron-containing cold material is one or more of cold-pressed balls, sintered ore, pelletized ore and lump ore.

[0050] Specifically, the composition requirements of the cold-pressed balls are that the TFe content is ≥45%, the compressive strength of the cold-pressed balls is ≥1400N / piece, and the water content is <3%.

[0051] It should be noted that in the present invention, the composition, strength and water content of the cold-pressed balls need to be strictly controlled. In the converter steelmaking process, the cold-pressed balls are added using a high-level silo for charging, and are prone to breakage when added in the high-level silo, requiring a compressive strength of not less than 1400N / piece. When the water content is higher than 3%, the cold-pressed balls are instantly heated under high temperature conditions, and excessive water vapor can easily cause the cold-pressed balls to burst, and improper operation can easily cause splashing. In order to ensure the recovery amount in the cold-pressed balls, the TFe content in the cold-pressed balls should be ≥45%. If it is lower than this, the slag components formed by the non-iron components in the cold-pressed balls are relatively large, and the iron recovery rate is easily lower than 30%. The addition of cold-pressed balls does not have the economic efficiency of recovering iron elements.

[0052] Specifically, the cold pressed balls are dust-removed coarse ash, dust-removed fine ash, iron oxide scale and steel slag magnetic separation powder.

[0053] Preferably, the weight percentages of coarse dust ash, fine dust ash, iron oxide scale and steel slag magnetic powder are: 25% to 30% coarse dust ash, 11% to 12% fine dust ash, 18% to 23% iron oxide scale, 40% to 48% steel slag magnetic powder, and 4% to 5% binder.

[0054] It should be noted that in the process of preparing cold-pressed balls, the dust-removed coarse ash, dust-removed fine ash, iron oxide scale and steel slag magnetic separation powder are first mixed, and then a binder is added to mix, and finally compacted.

[0055] Preferably, the dust removal coarse ash refers to the primary dust removal ash produced by dry dust removal of the converter, and the TFe content in the dust removal coarse ash is 29% to 54%.

[0056] Preferably, the dust removal fine ash refers to the primary dust removal ash produced by dry dust removal of the converter, and the TFe content in the dust removal coarse ash is 45% to 58%.

[0057] Preferably, during the continuous casting process, the ingot inevitably contacts with the oxidizing gas in the environment to produce iron oxide scale, and the TFe content in the iron oxide scale is 73% to 77%.

[0058] Preferably, the iron and iron oxides contained in the converter final slag are screened by strong magnetism to obtain steel slag magnetic separation powder, and the TFe content in the steel slag magnetic separation powder is 35% to 55%.

[0059] Preferably, the binder is mainly an organic binder, preferably a starch-based organic binder.

[0060] Specifically, the iron recovery rate R of cold pressed balls is calculated by the following formula: Fe , R Fe ≤30%, the ingredients need to be re-proportioned;

[0061]

[0062] It should be noted that the iron recovery rate R of cold pressed balls needs to be calculated. Fe In formula (1), R Fe Indicates the theoretical recovery rate of iron, %; w TFe，压 represents the mass percentage of TFe in the cold pressed ball, %; w MFe，压 Indicates the metal iron M in the cold pressed ball Fe Mass percentage, %; w FeO，压 Indicates the mass percentage of FeO in the cold pressed ball, %; w Fe2O3，压 Indicates the mass percentage of Fe2O3 in the cold pressed ball, %; w SiO2 , 压 Indicates the mass percentage of SiO2 in the cold pressed ball, %; B 压 Indicates the binary alkalinity w in the cold pressed ball CaO / w SiO2 , dimensionless number. TFe , slag represents the mass percentage of TFe in the final slag of converter smelting, %; B slag represents the binary basicity of the final slag w CaO / w SiO2 , a dimensionless number.

[0063] Specifically, the lime-based slag-making material includes one or more of lime and limestone;

[0064] Specifically, the magnesia slag-making material comprises one or more of magnesium balls, dolomite, and raw dolomite.

[0065] Specifically, the iron recovery rate of cold pressed balls is 30% <R Fe <60%;

[0066] When Si in molten iron is less than 0.20wt%, the auxiliary materials include 40% iron-containing cold material, 10% magnesium slag material, and 25% and 25% lime slag material, respectively, in terms of mass percentage;

[0067] When 0.20wt%≤Si<0.50wt% in molten iron, the auxiliary materials include 33-36% iron-containing cold material, 10-13% magnesium slag material, and 20-27% and 26-33% lime slag material, respectively, in terms of mass percentage;

[0068] When 0.50wt%≤Si<0.80wt% in molten iron, the auxiliary materials include 23-27% iron-containing cold material, 11-12% magnesium slag-making material, and 9-11% and 49-56% lime and limestone slag-making materials, respectively, in terms of mass percentage.

[0069] It should be noted that, based on the heat balance calculation, the silicon content of molten iron is differentiated. When the silicon content of molten iron increases, silicon oxidizes and enters the slag, and the content of SiO2 increases. In order to ensure the requirements of terminal dephosphorization, the slag alkalinity must be guaranteed; when the silicon content increases, silicon oxidation generates a large amount of heat. Therefore, with the increase of silicon content, the amount of lime slag-making material added to the molten pool increases. While ensuring the temperature of the molten pool, the temperature of the molten pool is maintained by adjusting the ratio of lime, limestone, and iron-containing cold material. The proportion of iron-containing cold material decreases. In order to ensure the MgO content in the slag and prevent severe erosion of the furnace lining, the magnesium slag-making material is slightly increased.

[0070] Specifically, the iron recovery rate of cold pressed balls is R Fe >60%;

[0071] When Si in molten iron is less than 0.20wt%, the auxiliary materials include 40% iron-containing cold material, 30% magnesium slag material, and 30% lime and 0% limestone slag materials, respectively, in terms of mass percentage.

[0072] When 0.20wt%≤Si<0.50wt% in molten iron, the auxiliary materials include 40-50% iron-containing cold material, 22-30% magnesium slag material, and 20-27% and 0-10% lime and limestone slag materials, respectively, in terms of mass percentage;

[0073] When 0.50wt%≤Si<0.80wt% in molten iron, the auxiliary materials include 35-38% iron-containing cold material, 17-18% magnesium slag-making material, and 20-24% and 10-27% lime and limestone slag-making materials, respectively, in terms of mass percentage.

[0074] It should be noted that the iron recovery rate is relatively high, and the iron recovered from iron-containing cold materials can further increase production, offset part of the auxiliary materials, and reduce costs.

[0075] Specifically, in step S3, the oxygen lance uses oxygen blowing throughout the entire process. The top blowing lance position in the early stage of smelting is 1.3-1.5m, the top blowing lance position in the middle stage of smelting is 1.4-1.5m, the top blowing lance position in the late stage of smelting is 1.4-1.6m, and the top blowing lance position at the end of smelting is 1.1-1.3m.

[0076] It should be noted that in the present invention, when the above-mentioned blowing method is used for control, the generation of highly oxidizing slag caused by the excessively high gun position can be reduced in the early, middle and late stages of smelting. The source of slag oxidation is mainly due to the melting of iron-containing cold material (cold-pressed balls), which can increase the recovery of iron-containing cold material. If the gun position is too high and is not within the above-mentioned specified range, it is easy to cause the slag oxidation to be too high. Excessive oxidation will lead to excessive oxidation of iron, and at the same time, the erosion of the furnace lining will be aggravated. The recovery of iron-containing cold material requires [C] in the converter molten pool to reduce the cold material to recover the metallic iron therein; if it is over-oxidized, the iron loss is too high, and the purpose of iron recovery cannot be achieved. If the gun position is too low and is not within the above-mentioned specified range, combined with the top blowing intensity described in this case, it is bound to cause [C] in the molten pool to oxidize too quickly, and the molten pool will heat up quickly, which is not conducive to the reduction of iron-containing cold material. In addition, a too low gun position has a greater scouring intensity on the furnace bottom, and the lining loss increases, affecting the life of the converter.

[0077] Specifically, in step S3, the top blowing intensity in the early stage of smelting is 3.4-3.9 Nm 3 / (min·t -1 ), the top blowing intensity in the middle stage of smelting is 3.5~4.1Nm 3 / (min·t -1 ), the top blowing intensity in the later stage of smelting is 3.6~4.2Nm 3 / (min·t -1 ), the top blowing intensity at the end of blowing is 3.7~4.2Nm 3 / (min·t -1 ).

[0078] Specifically, in step S3, the bottom blowing intensity in the early stage of smelting is 0.06-0.08Nm 3 / (min·t- 1 ), the bottom blowing intensity in the middle stage of smelting is 0.02~0.04Nm 3 / (min·t -1 ), the bottom blowing intensity in the later stage of smelting is 0.05~0.06Nm 3 / (min·t -1 ), stir for 1 to 3 minutes after blowing, and the bottom blowing intensity is 0.04 to 0.06 Nm 3 / (min·t -1 ).

[0079] It should be noted that by coordinating top blowing and bottom blowing and controlling their intensity within the above range, the stirring capacity of the molten pool can be improved to promote the recovery of iron in cold-pressed balls in the early and middle stages of smelting into the molten pool. If the top blowing intensity or the bottom blowing intensity is higher than the above range, due to the low gun position used in the operation, the oxidizing slag produced in the early slag making combined with the excessive impact strength is easy to cause lining erosion. If the top blowing intensity or the bottom blowing intensity is lower than the above range, the impact depth of the molten pool is insufficient, the stirring capacity of the molten pool is low, and the recovery rate is low.

[0080] Specifically, in step S3, the oxygen pressure in the early stage of smelting is 0.7-0.8 MPa, the oxygen pressure in the middle stage of smelting is 0.7-0.8 MPa, the oxygen pressure in the late stage of smelting is 0.7-0.9 MPa, and the oxygen pressure at the end of blowing is 0.7-0.9 MPa.

[0081] In order to more clearly describe the present invention, it is further illustrated by the following examples and comparative examples.

[0082] Example 1

[0083] The method for producing cold pressed balls comprises the following steps:

[0084] The dust removal coarse ash, dust removal fine ash, iron oxide scale and steel slag magnetic separation powder are mixed according to the proportions shown in Table 1, the mixture is preliminarily stirred, transported into a mixer, water and a binder are added for stirring and mixing, and after mixing, the raw materials are placed in a ball press for ball pressing, the mixture is preliminarily pre-pressed and shaped, the pre-pressed raw materials are placed in a finished product ball press for pressing and shaping, and sieved to obtain cold-pressed balls with size and strength that meet the requirements.

[0085] Table 1 Composition and ratio of cold pressed balls (unit %)

[0086] Iron-containing materials Proportion (kg / t) TFe <![CDATA[SiO2]]> CaO MgO MFe FeO <![CDATA[Fe2O3]]> Iron oxide scale 250 72.7 0.8 0.1 0.0 / 55.5 42.2 Dust removal 305 52.6 1.8 6.3 1.3 / 54.1 15.0 Dust removal 145 34.9 4.3 24.0 3.4 / 35.9 10.0 Steel slag magnetic separation 300 42.5 15.6 35.1 7.7 30.0 16.0 / Binder 50 / 29.5 / / / / / total 1050 49.5 7.2 15.2 3.0 8.6 38.5 15.8

[0087] The cold pressed ball formula is shown in Table 1. The TFe content of the cold pressed ball is 49.5%, the average compressive strength of the cold pressed ball is 2243N / piece, and the water content is 1.2%.

[0088] The basicity of the final slag of the converter is set to 2.8, and the TFe content of the final slag is about 14%. The theoretical iron recovery rate of the cold-pressed briquette is calculated as R Fe =40.14%, the application process of iron-containing cold material in the converter is as follows:

[0089] 1) After the converter slag splashing is completed, the Si content of the molten iron is 0.43% according to the detection center. Calculated by mass percentage, the auxiliary materials are prepared as follows: raw dolomite: 12%, lime: 25%, limestone: 30%, cold pressed balls 33%;

[0090] Carry out the base material laying operation: add all the raw dolomite, lime and limestone accounting for 35% of the total lime slag making amount, of which lime accounts for 10% of the total lime slag making amount, limestone accounts for 25% of the total lime slag making amount, and 50% of the total cold-pressed balls to the bottom of the molten pool.

[0091] 2) Add all the scrap steel into the converter and carry out iron addition operation. The scrap steel loading amount is 6.5t and the molten iron loading amount is 91t.

[0092] 3) Lower the oxygen lance from the starting position to the blowing point, the oxygen lance position is 1.3-1.5m, start blowing, start feeding after 1min of blowing, first add the remaining 50% of the cold pressed balls, and use the principle of small amounts and multiple times to perform the cold pressed ball feeding operation, and then add lime and limestone accounting for 35% of the total amount of lime slag, of which lime accounts for 10% of the total amount of lime slag, and limestone accounts for 25% of the total amount of lime slag. The top blowing intensity is 3.4-3.66Nm 3 / (min·t -1 ), bottom blowing strength is 0.062Nm 3 / (min·t -1 ), the bottom blowing gas is N2.

[0093] 4) After blowing for 4 minutes, continue to add the remaining lime and limestone in small amounts and multiple times, and add them all within 7 minutes. The top blowing gun position is 1.4-1.5m, and the top blowing intensity is 3.5-3.85Nm 3 / (min·t -1 ), bottom blowing strength is 0.037Nm 3 / (min·t -1 ), the bottom blowing gas is N2.

[0094] 5) 7 minutes later and 1 to 2 minutes before the end of smelting, the top blowing gun position is 1.4 to 1.6m, and the top blowing intensity is 3.66 to 4.03Nm 3 / (min·t -1 ), bottom blowing strength is 0.051Nm 3 / (min·t -1 ), after about 10 minutes of blowing, the bottom blowing gas is switched to nitrogen and argon. After 10 minutes, the bottom blowing gas is Ar.

[0095] 6) 1 to 2 minutes before the end of blowing, perform gun pressure operation, lower the gun position to 1.1 to 1.3m, and the oxygen flow rate is 3.85 to 4.03Nm 3 / (min·t -1 ), bottom blowing strength is 0.051Nm 3 / (min·t -1 ), the bottom blowing gas is Ar.

[0096] After blowing to the end of smelting, lift the gun to the starting position and perform post-stirring operation on the molten pool to ensure uniform and stable composition of the molten pool and reduce the oxidizability of the final slag. The post-stirring bottom blowing intensity is set to 300Nm 3 / h, post-stirring time is 3min, the furnace is shaken to carry out steel tapping operation, and the slag is poured after the steel tapping is completed, and the slag retention operation is adopted, and the slag retention amount is 1 / 3 to 1 / 2 of the slag amount.

[0097] 7) Lower the oxygen lance from the starting position to the blowing point, and use nitrogen to perform slag splashing operation. The slag splashing time is 3 to 5 minutes. After the slag splashing is completed, lay the bottom material and repeat the converter production.

[0098] Example 2

[0099] The preparation process of Example 2 is substantially the same as that of Example 1, except that the recovery rate of the iron-containing cold material in Example 2 is RFe=61.3%, and the addition ratio of the cold pressed balls is changed. The specific implementation plan is as follows:

[0100] 1) After the converter slag splashing is completed, the Si content of the molten iron is 0.52% according to the detection center, and the auxiliary materials are prepared according to the mass percentage: raw dolomite: 25%, lime: 25%, limestone: 10%, cold pressed balls 40%;

[0101] Carry out the base material laying operation: add all the raw dolomite, lime and limestone accounting for 35% of the total amount of lime slag, of which lime accounts for 25% of the total amount of lime slag, limestone accounts for 10% of the total amount of lime slag, and 50% of the total amount of cold-pressed balls to the bottom of the molten pool.

[0102] 2) Add all the scrap steel into the converter and carry out iron addition operation. The scrap steel loading amount is 7t and the molten iron loading amount is 90t.

[0103] 3) Lower the oxygen lance from the starting position to the blowing point, the oxygen lance position is 1.4-1.6m, start blowing, start feeding after 1min of blowing, first add the remaining 50% of the cold pressed balls, and use the principle of small amounts and multiple times to feed the cold pressed balls, and then add lime and limestone accounting for 35% of the total amount of lime slag, of which lime accounts for 15% of the total amount of lime slag, and limestone accounts for 10% of the total amount of lime slag. The top blowing intensity is 3.52-3.89Nm 3 / (min·t -1 ), bottom blowing strength is 0.044Nm 3 / (min·t -1 ), the bottom blowing gas is N2.

[0104] 4) After blowing for 4 minutes, continue to add the remaining lime and limestone in small amounts and multiple times, and add them all within 7 minutes. The top blowing gun position is 1.5-1.6m, and the top blowing intensity is 3.70-3.89Nm 3 / (min·t -1 ), bottom blowing strength is 0.044Nm 3 / (min·t -1 ), the bottom blowing gas is N2.

[0105] 5) 7 minutes later and 1 to 2 minutes before the end of smelting, the top blowing gun position is 1.5 to 1.7m, and the top blowing intensity is 3.70 to 4.07Nm3 / (min·t -1 ), bottom blowing strength is 0.044Nm 3 / (min·t -1 ), after about 10 minutes of blowing, the bottom blowing gas is switched to nitrogen and argon. After 10 minutes, the bottom blowing gas is Ar.

[0106] 6) 1 to 2 minutes before the end of blowing, perform the gun pressure operation, lower the gun position to 1.2 to 1.4m, and the oxygen flow rate is 3.70 to 4.07Nm 3 / (min·t -1 ), bottom blowing strength is 0.044Nm 3 / (min·t -1 ), the bottom blowing gas is Ar.

[0107] After blowing to the end of smelting, lift the gun to the starting position, and stir the molten pool to ensure uniform and stable composition of the molten pool and reduce the oxidation of the final slag. The post-stirring bottom blowing intensity is set to 300Nm3 / h, the post-stirring time is 3min, and the furnace is shaken for steel tapping. After steel tapping, the slag is poured and the slag retention operation is adopted. The slag retention amount is 1 / 3 to 1 / 2 of the slag amount. Repeat this production step for the application of cold pressed balls in converter production.

[0108] 7) Lower the oxygen lance from the starting position to the blowing point, and use nitrogen to perform slag splashing operation. The slag splashing time is 3 to 5 minutes. After the slag splashing is completed, lay the bottom material and repeat the converter production.

[0109] Comparative Example 1

[0110] The preparation process of Comparative Example 1 is substantially the same as that of Example 1, except that the cold pressed balls are not added in Comparative Example 1:

[0111] 1) After the converter slag splashing is completed, the Si content of molten iron is 0.43% according to the detection center, and the auxiliary materials are prepared according to the mass percentage: raw dolomite: 35%, lime: 20%, limestone: 45%, cold pressed balls 0%;

[0112] Carry out the base material laying operation: add all the raw dolomite, lime and limestone accounting for 35% of the total lime slag making amount, of which lime accounts for 10% of the total lime slag making amount, limestone accounts for 25% of the total lime slag making amount, and 0% of the cold pressed balls to the bottom of the molten pool.

[0113] Comparative Example 2

[0114] The preparation process of Comparative Example 2 is substantially the same as that of Example 1, except that in Comparative Example 2:

[0115] 1) After the converter slag splashing is completed, the Si content of the molten iron is 0.43% according to the detection center, and the auxiliary materials are prepared according to the mass percentage: raw dolomite: 12%, lime: 25%, limestone: 30%, cold pressed balls 33%;

[0116] Carry out the base material laying operation: add 70% of raw dolomite, 35% of lime and limestone of the total lime slag making, of which lime accounts for 10% of the total lime slag making, limestone accounts for 25% of the total lime slag making, and 50% of cold pressed balls to the bottom of the molten pool.

[0117] 3) Lower the oxygen lance from the starting position to the blowing point, the oxygen lance position is 1.3-1.5m, start blowing, and start adding materials after 1 minute of blowing. First add the remaining 30% of raw dolomite and 50% of cold-pressed balls. Use the principle of small amounts and multiple times to add cold-pressed balls. Then add lime and limestone that account for 35% of the total amount of lime slag, of which lime accounts for 10% of the total amount of lime slag, and limestone accounts for 25% of the total amount of lime slag. The top blowing intensity is 3.4-3.66Nm 3 / (min·t -1 ), bottom blowing strength is 0.062Nm 3 / (min·t -1 ), the bottom blowing gas is N2.

[0118] Comparative Example 3

[0119] The preparation process of Comparative Example 3 is substantially the same as that of Example 1, except that in Comparative Example 3:

[0120] 1) After the converter slag splashing is completed, the Si content of the molten iron is 0.43% according to the detection center, and the auxiliary materials are prepared according to the mass percentage: raw dolomite: 12%, lime: 25%, limestone: 30%, cold pressed balls 33%;

[0121] Carry out the base material operation: add all the raw dolomite, 0% lime, 0% limestone, and 50% cold pressed balls to the bottom of the molten pool.

[0122] 3) Lower the oxygen lance from the starting position to the blowing point, the oxygen lance position is 1.3-1.5m, start blowing, start feeding after 1min, add 50% of cold pressed balls, and use the principle of small amounts and multiple times to add cold pressed balls, and then add 50% of the total amount of lime slag and limestone, of which lime accounts for 20% of the total amount of lime slag, and limestone accounts for 30% of the total amount of lime slag. The top blowing intensity is 3.4-3.66Nm 3 / (min·t -1 ), bottom blowing strength is 0.062Nm 3 / (min·t -1 ), the bottom blowing gas is N2.

[0123] Comparative Example 4

[0124] The preparation process of Comparative Example 4 is substantially the same as that of Example 1, except that the recovery rate of the iron-containing cold material in Comparative Example 4 is RFe=37.7%. The specific implementation method is as follows:

[0125] 1) After the converter slag splashing is completed, the Si content of molten iron is 0.67% according to the detection center, and the auxiliary materials are prepared according to the mass percentage: raw dolomite: 12%, lime: 10%, limestone: 52%, cold pressed balls 26%;

[0126] Carry out the base material operation: add all the raw dolomite, lime and limestone accounting for 40% of the total lime slag making, of which lime accounts for 0% of the total lime slag making, limestone accounts for 40% of the total lime slag making, and 50% of the cold pressed balls to the bottom of the molten pool.

[0127] 2) Add all the scrap steel into the converter and carry out iron addition operation. The scrap steel loading amount is 7.3t and the molten iron loading amount is 95t.

[0128] 3) Lower the oxygen lance from the starting position to the blowing point, the oxygen lance position is 1.5-1.6m, start blowing, start adding materials after 1min of blowing, first add the remaining 50% of the cold pressed balls, and use the principle of small amounts and multiple times to add cold pressed balls, and then add lime and limestone accounting for 40% of the total amount of lime slag, of which lime accounts for 10% of the total amount of lime slag, and limestone accounts for 30% of the total amount of lime slag. Top blowing intensity 3.16-3.33Nm 3 / (min·t -1 ), bottom blowing strength is 0.035Nm 3 / (min·t -1 ), the bottom blowing gas is N2.

[0129] 4) After blowing for 4 minutes, continue to add the remaining lime and limestone in small amounts and multiple times until all are added to the end of smelting. The top blowing gun position is 1.5-1.7m, and the top blowing intensity is 3.33-3.50Nm 3 / (min·t -1 ), bottom blowing strength is 0.035Nm 3 / (min·t -1 ), the bottom blowing gas is N2.

[0130] 5) From 7 minutes to 1 to 2 minutes before the end of smelting, the top blowing gun position is 1.6 to 1.7 m, and the top blowing intensity is 3.33 to 3.50 Nm 3 / (min·t -1 ), bottom blowing strength is 0.035Nm 3 / (min·t -1), after about 10 minutes of blowing, the bottom blowing gas is switched to nitrogen and argon. After 10 minutes, the bottom blowing gas is Ar.

[0131] 6) 1 to 2 minutes before the end of blowing, perform the gun pressure operation, lower the gun position to 1.3 to 1.4m, and the oxygen flow rate is 3.33 to 3.50Nm 3 / (min·t -1 ), bottom blowing strength is 0.035Nm 3 / (min·t -1 ), the bottom blowing gas is Ar.

[0132] After blowing to the end of smelting, lift the gun to the starting position without post-stirring, shake the furnace to perform steel tapping operations, and after steel tapping is completed, pour the slag, and adopt the slag retention operation, with the amount of slag retained being 1 / 3 to 1 / 2 of the slag volume.

[0133] 7) Lower the oxygen lance from the starting position to the blowing point, and use nitrogen to perform slag splashing operation. The slag splashing time is 3 to 5 minutes. After the slag splashing is completed, lay the bottom material and repeat the converter production.

[0134] Performance Testing

[0135] The above-mentioned Examples 1-2 and Comparative Examples 1-4 were subjected to performance tests, mainly including steel material consumption, comprehensive ash consumption and end-point P content. The test results are shown in Table 2.

[0136] Table 2 Performance test results

[0137] Group Steel material consumption (kg / t) Comprehensive ash consumption (kg / t) End point P content (%) Example 1 1047.48 37.4 0.0237 Example 2 1046.70 35.6 0.0253 Comparative Example 1 1057.90 42.3 0.0314 Comparative Example 2 1050.20 38.7 0.0284 Comparative Example 3 1049.36 38.5 0.0308 Comparative Example 4 1054.30 39.4 0.0306

[0138] It can be seen from the combination of Examples 1-2 and Comparative Examples 1-4 and with reference to Table 2 that when the converter steelmaking process provided by the present invention is used for production, iron-containing cold materials are used for production, especially cold pressed balls are used, and the proportion and addition amount are controlled and the corresponding blowing process is coordinated, so that the recovery amount of iron-containing cold materials is increased, thereby increasing the steel output, and ultimately reducing the consumption of steel materials and the comprehensive ash consumption, wherein the consumption of steel materials is below 1047.48 kg / t, the comprehensive ash consumption is below 37.4 kg / t, and the final P content is below 0.0253%.

[0139] Combining Example 1 and Comparative Example 2, it can be seen that when the scheme of Comparative Example 2 is implemented, the difficulty of slagging increases. Compared with the slagging law in Example 1, the slagging method in Comparative Example 2 causes serious erosion of the furnace bottom, insufficient protection of the furnace bottom, and is prone to form a magnesia slag system in the early stage of smelting, making slagging difficult and increasing the consumption of steel materials.

[0140] Combining Example 1 and Comparative Example 3, it can be seen that when the scheme of Comparative Example 3 is implemented, it will cause serious erosion of the furnace bottom in the early stage of smelting. Only the time during the blowing process is used for slagging, which increases the difficulty of slagging, is not conducive to early slagging, and affects dephosphorization.

[0141] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A converter steelmaking process using iron-containing cold material, characterized in that: The following steps are involved: S1: preparing auxiliary materials according to the silicon content in molten iron and the iron recovery rate of cold-pressed balls in the iron-containing cold material, wherein the auxiliary materials include magnesium slag-making material, lime slag-making material and iron-containing cold material; After the slag splashing of the converter is completed, 90% to 100% of the total amount of magnesium slag-making material, 30% to 40% of the total amount of lime slag-making material and 30% to 50% of the total amount of iron-containing cold material are added in sequence to form the bottom material; S2: adding scrap steel and molten iron into the converter; S3: lower the oxygen lance from the starting position to the blowing point and start blowing; S4: After blowing for a period of time, start adding materials, and add 50% to 70% of the total amount of iron-containing cold materials, 30% to 40% of the total amount of lime slag materials, and the remaining magnesium slag materials in sequence; S5: Continue blowing and add the remaining lime-based slag-making material; S6: After blowing to the end of smelting, lift the gun to the starting position and perform the tapping operation. After the tapping is completed, slag is poured and the slag retention operation is adopted. The slag retention amount is 1 / 3 to 1 / 2 of the slag amount. S7: Lower the oxygen gun from the starting position to the blowing point, and use nitrogen to perform slag splashing operation. The slag splashing time is 3 to 5 minutes. After the slag splashing is completed, lay the base material.

2. The converter steelmaking process according to claim 1, characterized in that: The iron-containing cold material is one or more of cold-pressed balls, sintered ore, pelletized ore and lump ore.

3. The converter steelmaking process according to claim 2, characterized in that: The composition requirements of cold-pressed balls are TFe content ≥ 45%, cold-pressed ball compressive strength ≥ 1400N, and water content < 3%; the iron recovery rate of cold-pressed balls is greater than 30%, and the calculation formula of iron recovery rate is as follows:

4. The converter steelmaking process according to claim 2, characterized in that: The cold pressed balls are dedusted coarse ash, dedusted fine ash, iron oxide scale and steel slag magnetic separation powder.

5. The converter steelmaking process according to claim 2, characterized in that: The iron recovery rate of cold pressed balls is 30% <R Fe <60%; When Si in molten iron is less than 0.20wt%, the auxiliary materials include 40% iron-containing cold material, 10% magnesium slag material, and 25% and 25% lime slag material, respectively, in terms of mass percentage; When 0.20wt%≤Si<0.50wt% in molten iron, the auxiliary materials include 33-36% iron-containing cold material, 10-13% magnesium slag material, and 20-27% and 26-33% lime slag material, respectively, in terms of mass percentage; When 0.50wt%≤Si<0.80wt% in molten iron, the auxiliary materials include 23-27% iron-containing cold material, 11-12% magnesium slag-making material, and 9-11% and 49-56% lime and limestone slag-making materials, respectively, in terms of mass percentage.

6. The converter steelmaking process according to claim 2, characterized in that: Iron recovery rate R of cold pressed balls Fe >60%; When Si in molten iron is less than 0.20wt%, the auxiliary materials include 40% iron-containing cold material, 30% magnesium slag material, and 30% lime and 0% limestone slag materials, respectively, in terms of mass percentage. When 0.20wt%≤Si<0.50wt% in molten iron, the auxiliary materials include 40-50% iron-containing cold material, 22-30% magnesium slag material, and 20-27% and 0-10% lime and limestone slag materials, respectively, in terms of mass percentage; When 0.50wt%≤Si<0.80wt% in molten iron, the auxiliary materials include 35-38% iron-containing cold material, 17-18% magnesium slag-making material, and 20-24% and 10-27% lime and limestone slag-making materials, respectively, in terms of mass percentage.

7. The converter steelmaking process according to claim 1, characterized in that: In step S3, oxygen is used for blowing in the whole process of the oxygen lance. The top blowing lance position is 1.3-1.5m in the early stage of smelting, 1.4-1.5m in the middle stage of smelting, 1.4-1.6m in the late stage of smelting and 1.1-1.3m at the end of smelting.

8. The converter steelmaking process according to claim 1, characterized in that: In step S3, the top blowing intensity in the early stage of smelting is 3.4-3.9 Nm 3 / (min·t -1 ), the top blowing intensity in the middle stage of smelting is 3.5~4.1Nm 3 / (min·t -1 ), the top blowing intensity in the later stage of smelting is 3.6~4.2Nm 3 / (min·t -1 ), the top blowing intensity at the end of blowing is 3.7~4.2Nm 3 / (min·t -1 ).

9. The converter steelmaking process according to claim 1, characterized in that: In step S3, the bottom blowing intensity in the early stage of smelting is 0.06-0.08Nm 3 / (min·t- 1 ), the bottom blowing intensity in the middle stage of smelting is 0.02~0.04Nm 3 / (min·t -1 ), the bottom blowing intensity in the later stage of smelting is 0.05~0.06Nm 3 / (min·t -1 ), stir for 1 to 3 minutes after blowing, and the bottom blowing intensity is 0.04 to 0.06 Nm 3 / (min·t -1 ).

10. The converter steelmaking process according to claim 1, characterized in that: The magnesia slag-making material comprises one or more of magnesium balls, dolomite and raw dolomite.

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