A slag blending method for recycling spring steel 55SiCr refined slag

Abstract

The invention relates to the technical field of metallurgy, and in particular to a slag blending method for recycling spring steel 55SiCr refined slag, controlling the content of refractory MgO and Al2O3 in a ladle, the content of Al and Ti in a converter primary refining and LF refining alloy, slag removal with a small bottom blowing flow rate after the converter, adding spring steel special refined slag with a specific composition before LF, bottom blowing argon with a small flow rate during LF refining and soft blowing, controlling the basicity of the refined final slag, recycling the refined final slag by scooping slag from the ladle before continuous casting, crushing it after drying, adding a certain proportion of lime for mixing and stirring evenly, so as to obtain a new refined slag with a specific composition suitable for cord steel, realize the recycling and reuse of refined slag, and have the economic benefit of reducing production costs by simple and convenient operation.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, in particular to a slag matching method for recycling spring steel 55SiCr refined slag. Background Art

[0002] 55SiCr belongs to Si-Cr spring steel and is used to manufacture automobile suspension springs. The suspension springs are subjected to reciprocating compression during the driving process of the car, playing the role of buffering and shock absorption. Therefore, when using it, 55SiCr spring steel is required to have high anti-elasticity, high mechanical properties and high fatigue life, and more stringent standards are put forward for the chemical composition, inclusions, organization and plasticity of the wire rod. The tensile strength of the spring steel wire after oil quenching is ≥1900MPa, and the manufacturing stress is ≥1100MPa. The fatigue life of the suspension spring made of 55SiCr spring steel reaches more than 300,000 times.

[0003] At present, the control of 55SiCr inclusions is mainly achieved through the study of the coupling reaction of alloy, refined slag, refractory materials with molten steel and inclusions to obtain plastic inclusion control. The suspension spring is refined with a suitable refined slag system and the refined slag ratio is optimized to achieve the purpose of effectively controlling the morphology of inclusions; the refining process optimizes the deoxidation process and alloy composition, and controls the mass fraction of Al2O3 in the inclusions to ≤20%, so that the endogenous inclusions have good plastic deformation ability and the lateral size is ≤10μm; combined with the high-efficiency inclusion purification technology of electromagnetic stirring in the tundish, the inclusions are controlled to fully collide, aggregate and float up for removal, and the use of high-quality refractory materials is studied to control the entry of foreign inclusions into the molten steel, so as to achieve the smelting of pure steel with a stable size of foreign inclusions ≤60μm.

[0004] In existing production applications, slag is mainly used as solid waste. Because it contains some iron components in molten steel, it will be crushed by hot stuffing method after recycling, and then the iron powder will be adsorbed by magnets. The iron powder will be re-sintered and iron-making. Only 8.0% to 12% of the iron powder can be recovered from 1 ton of slag, that is, 80 to 120 kg. The remaining waste is treated as solid waste, and the slag is wasted a lot.

[0005] In addition, due to the low basicity of the slag during the refining process, after the high-MgO ladle bricks on the inner wall of the ladle are corroded, the ladle brick refractory will react chemically with the slag. The MgO content in the slag after refining will increase from the original 0.85%~1.45% to 12%~19%. If the high-MgO slag is directly recycled and reused in 55SiCr, a large amount of Mg-Si inclusions with poor deformability will be formed, which will eventually affect the fatigue performance and life of the springs made of 55SiCr wire rods. Therefore, the recycling value of 55SiCr refined slag was not great before, and it was generally treated as solid waste. Summary of the invention

[0006] The technical problem to be solved by the present invention is: in order to overcome the problem that the recovery rate of 55SiCr refined slag in the prior art is low and it cannot be directly recycled and reused, a slag preparation method for recycling and utilizing 55SiCr refined slag of spring steel is provided.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a slag matching method for recycling spring steel 55SiCr refined slag, a slag matching method for recycling spring steel 55SiCr refined slag, characterized in that:

[0008] The method is as follows: control the content of MgO and Al2O3 in the refractory material inside the ladle, the content of Al and Ti in the primary refining of the converter and the LF refining alloy, remove the slag with a small bottom blowing flow rate after the converter, add spring steel special refined slag before LF, blow argon with a small bottom flow rate in the ladle during the LF, control the basicity of the refined final slag, remove the slag from the ladle before continuous casting, crush it after drying, add a certain proportion of lime for mixing and stirring, and obtain new refined slag suitable for cord steel. The specific steps are as follows:

[0009] (1) A 120 t top and bottom composite blowing converter is used and 70-90% by weight of desulfurized iron water is added, and the rest is clean scrap steel or pig iron as raw materials for primary smelting in the converter;

[0010] (2) The refractory materials inside the ladle used in the smelting process must meet the requirements of MgO ≥ 85.0% and Al2O3 ≤ 1.0%;

[0011] (3) The converter alloy begins to be charged after 1 / 3 of the molten steel has been tapped, first adding low-titanium and low-aluminum ferrosilicon, then low-carbon ferrochrome, and finally adding metallic manganese, and the Al and Ti contents in the alloy are ≤0.015%;

[0012] (4) The converter uses a slide plate and a slag cone to block the slag. After the molten steel is left to stand, the slide plate is opened to release the steel.

[0013] (5) After the converter is tapped, the slag is removed by a slag remover, and the ladle bottom must be blown to remove the slag;

[0014] (6) Before refining, the ladle is added with special refined slag for spring steel 55SiCr wire rod, which has the following components: CaO: 45.0% to 55.0%, SiO2: 43.0% to 50.0%, Al2O3≤0.36%, MgO≤1.45%, MnO, TiO2≤0.08%, other components all ≤0.06%, and basicity 0.90 to 1.28. 1000 kg / furnace of special refined slag for spring steel 55SiCr wire rod;

[0015] (7) During the refining process, low-titanium and low-aluminum ferrosilicon, low-carbon ferrochrome, and metallic manganese are added, and the Al and Ti contents in the alloy are 0.015% to 0.030%;

[0016] (8) The refining process is ≥30min, the ladle argon blowing is controlled at 290-350NL / min throughout the process, soft blowing is performed at the end of refining, the ladle argon blowing is controlled throughout the process, quicklime is added, and the basicity of the final slag is controlled at 0.70-0.80;

[0017] (9) After the refining soft blowing is completed, the slag is removed by the slag removal machine after the steel is tapped. During the slag removal process, the ladle bottom blowing is turned off and the removed slag is placed in an empty slag basin;

[0018] (10) Using ladle baking equipment to fully bake and dry the slag in the slag basin;

[0019] (11) After drying, 25 to 30 kg of quicklime is added to every 300 kg of the slag, which is poured into an industrial crusher and crushed and stirred thoroughly to obtain a new refined slag with the composition of CaO: 35.0% to 40.0%, SiO2: 35.0% to 37.0%, Al2O3: 1.80% to 3.40%, MgO: 12.0% to 19.0%, MnO ≤ 1.80%, TiO2 ≤ 0.40%, and other components ≤ 0.06%, and the basicity of 0.99 to 1.08, which is suitable for cord steel.

[0020] The invention further comprises that the chemical composition of the spring steel 55SiCr wire rod is calculated by mass percentage, and the ratio is C: 0.51-0.59%, Si: 1.20-1.60%, Mn: 0.50-0.80%, Cr: 0.50-0.80%, P≤0.025%, S≤0.020%, Ni≤0.35%, Cu≤0.25%, and the rest is iron and unavoidable impurities.

[0021] The method further comprises the step (3) of starting to add materials to the converter alloy after 1 / 3 of the molten steel has been tapped, first adding 2400-2800 kg / furnace of low-titanium and low-aluminum ferrosilicon, then adding 1300-1500 kg / furnace of low-carbon ferrochrome, and finally adding 600-700 kg / furnace of metallic manganese.

[0022] The method further comprises the step (4) that the converter uses a slide plate and a slag stop cone to stop slag, and the slide plate is opened to release the steel after the molten steel is left to stand.

[0023] The method further comprises the step (5) of using a slag remover to remove slag after the converter taps out steel, wherein the ladle must be bottom blown for slag removal, and the bottom blowing flow rate is ≤200L / min.

[0024] The method further comprises the step (7) of adding 270-600 kg / furnace of low-titanium and low-aluminum ferrosilicon, 230-300 kg / furnace of low-carbon ferrochrome and 160-300 kg / furnace of metallic manganese during the refining process.

[0025] The method further comprises step (8) wherein the refining process is ≥30 min, the argon blowing of the ladle is controlled at 290-350 NL / min throughout the refining process, soft blowing is performed after the refining is completed, the soft blowing time is ≥25 min, the argon blowing of the ladle is controlled at ≤180 NL / min throughout the refining process, 80-120 kg / furnace of quicklime is added, and the basicity of the final slag of the refining is controlled at 0.70-0.80.

[0026] The method further comprises step (10) wherein the baking time is ≥45 min.

[0027] The beneficial effects of the present invention are as follows: the present invention provides a slag blending method for recycling spring steel 55SiCr refined slag, by controlling the refractory MgO and Al2O3 content inside the ladle, the Al and Ti content of the alloy in the converter primary refining and LF refining, slag removal with a small bottom blowing flow rate after the converter, adding spring steel special refined slag with a specific composition before LF, argon blowing with a small bottom flow rate during the whole process of LF refining and soft blowing, controlling the basicity of the refined final slag, and recycling the refined final slag by scooping the slag in the ladle before continuous casting, crushing it after drying, adding a certain proportion of lime to mix and stir evenly, so as to obtain a new refined slag with a specific composition suitable for cord steel, thereby realizing the recycling and reuse of refined slag, being simple and convenient to operate, and having the economic benefit of reducing production costs;

[0028] The invention obtains new refined slag suitable for cord steel by controlling the contents of MgO and Al2O3 in the refractory material inside the ladle, the contents of Al and Ti in the primary refining of the converter and the LF refining alloy, slag removal by small bottom blowing after the converter, adding spring steel special refined slag before LF, bottom blowing argon at a small flow rate in the ladle throughout the LF process, controlling the basicity of the refined final slag, slag removal in the ladle before continuous casting, crushing after drying, and adding a certain proportion of lime for mixing and stirring, thereby achieving 100% recycling of 55SiCr refined slag, and also reducing the production cost of cord steel and the cost of solid waste treatment. DETAILED DESCRIPTION

[0029] A slag matching method for recycling spring steel 55SiCr refined slag, a slag matching method for recycling spring steel 55SiCr refined slag:

[0030] The method is as follows: control the content of MgO and Al2O3 in the refractory material inside the ladle, the content of Al and Ti in the primary refining of the converter and the LF refining alloy, remove the slag with a small bottom blowing flow rate after the converter, add spring steel special refined slag before LF, blow argon with a small bottom flow rate in the ladle during the LF, control the basicity of the refined final slag, remove the slag from the ladle before continuous casting, crush it after drying, add a certain proportion of lime for mixing and stirring, and obtain new refined slag suitable for cord steel. The specific steps are as follows:

[0031] (1) A 120 t top and bottom composite blowing converter is used and 70-90% by weight of desulfurized iron water is added, and the rest is clean scrap steel or pig iron as raw materials for primary smelting in the converter;

[0032] (2) The refractory materials inside the ladle used in the smelting process must meet the requirements of MgO ≥ 85.0% and Al2O3 ≤ 1.0%;

[0033] (3) The converter alloy begins to be charged after 1 / 3 of the molten steel has been tapped. First, add 2400-2800 kg / furnace of low-titanium and low-aluminum ferrosilicon, then add 1300-1500 kg / furnace of low-carbon ferrochrome, and finally add 600-700 kg / furnace of metallic manganese. The Al and Ti contents in the alloy are ≤0.015%;

[0034] (4) The converter uses a slide plate and a slag cone to block the slag. After the molten steel is left to stand, the slide plate is opened to release the steel.

[0035] (5) After the converter is tapped, the slag is removed by a slag remover. The ladle must be blown bottom, and the bottom blowing flow rate is ≤200L / min;

[0036] (6) Before refining, the ladle is added with special refined slag for spring steel 55SiCr wire rod, which has the following components: CaO: 45.0% to 55.0%, SiO2: 43.0% to 50.0%, Al2O3≤0.36%, MgO≤1.45%, MnO, TiO2≤0.08%, other components all ≤0.06%, and basicity 0.90 to 1.28. 1000 kg / furnace of special refined slag for spring steel 55SiCr wire rod;

[0037] (7) In the refining process, low-titanium and low-aluminum ferrosilicon is 270-600 kg / furnace, low-carbon ferrochrome is 230-300 kg / furnace, and metallic manganese is 160-300 kg / furnace, and the Al and Ti contents in the alloy are 0.015% to 0.030%;

[0038] (8) The refining process is ≥30min, the ladle is argon-blown throughout the process, and the argon blowing flow rate is 290-350NL / min. After the refining, soft blowing is performed, and the soft blowing time is ≥25min. The ladle is argon-blown throughout the process, and the argon blowing flow rate is ≤180NL / min. Quicklime is added at 80-120kg / furnace, and the basicity of the final slag is controlled at 0.70-0.80;

[0039] (9) After the refining soft blowing is completed, the slag is removed by the slag removal machine after the steel is tapped. During the slag removal process, the ladle bottom blowing is turned off and the removed slag is placed in an empty slag basin;

[0040] (10) Use ladle baking equipment to fully bake and dry the slag in the slag basin, and the baking time shall be ≥45min;

[0041] (11) After drying, 25 to 30 kg of quicklime is added to every 300 kg of the slag, which is poured into an industrial crusher and crushed and stirred thoroughly to obtain a new refined slag with the composition of CaO: 35.0% to 40.0%, SiO2: 35.0% to 37.0%, Al2O3: 1.80% to 3.40%, MgO: 12.0% to 19.0%, MnO ≤ 1.80%, TiO2 ≤ 0.40%, and other components ≤ 0.06%, and the basicity of 0.99 to 1.08, which is suitable for cord steel.

[0042] The chemical composition of spring steel 55SiCr wire rod is calculated by mass percentage, and the ratio is C: 0.51~0.59%, Si: 1.20~1.60%, Mn: 0.50~0.80%, Cr: 0.50~0.80%, P≤0.025%, S≤0.020%, Ni≤0.35%, Cu≤0.25%, and the rest is iron and unavoidable impurities.

[0043] Example 1

[0044] In actual production, a total of 7 furnaces of 55SiCr were smelted in pouring 1. The specific operation steps are as follows:

[0045] (1) A 3#120t top and bottom composite blowing converter was used for batching, and 88.5-92.2 tons of desulfurized hot metal and 26.7-31.5 tons of pig iron were added for primary smelting in the converter;

[0046] (2) Low-aluminum-magnesium-carbon steel ladles are used for converter smelting, and internal refractory materials are sampled and analyzed in advance, with MgO: 87.69% to 88.56%, Al2O3: 0.21% to 0.36%;

[0047] (3) After 35-40 tons of molten steel is discharged from the converter, alloys are added. First, 2573-2718 kg / furnace of low-titanium and low-aluminum ferrosilicon is added, then 1356-1421 kg / furnace of low-carbon ferrochrome is added, and finally 621-656 kg / furnace of metallic manganese is added. The three types of alloys are sampled and analyzed in advance, among which the Al content is 0.007%-0.012% and the Ti content is 0.002%-0.015%;

[0048] (4) The converter uses a slide plate and a slag cone to block slag. The molten steel is left to stand for 3.5 to 4.3 seconds before the slide plate is opened to release the steel. No slag is discharged.

[0049] (5) After the converter is tapped, a car-type slag remover is used to remove slag. During the slag removal process, argon is blown from the bottom of the ladle at a flow rate of 103 to 155 L / min. Visually, there is no residue on the surface of the molten steel and the slag is removed cleanly;

[0050] (6) Before refining, 1000 kg of spring steel special refined slag with the following components added into each ladle: CaO: 46.5% to 54.7%, SiO2: 43.6% to 49.9%, Al2O3: 0.22% to 0.33%, MgO: 1.16% to 1.43%, MnO: 0.043% to 0.077%, TiO2: 0.045% to 0.075%, other components ≤ 0.03%, basicity 0.93 to 1.25;

[0051] (7) During the refining process, 278-436 kg / furnace of low-titanium and low-aluminum ferrosilicon, 255-278 kg / furnace of low-carbon ferrochrome, and 188-246 kg / furnace of metallic manganese were added. The three types of alloys were sampled and analyzed in advance, with Al content of 0.018%-0.026% and Ti content of 0.022%-0.025%.

[0052] (8) The refining process lasts 30.5 to 35.5 minutes, the argon blowing of the ladle is controlled at 290 to 305 NL / min throughout the process, and soft blowing is performed at the end of refining, the soft blowing time is 25.5 to 30.5 minutes, the argon blowing of the ladle is controlled at 140 to 155 NL / min throughout the process, and quicklime is added at 83 to 96 kg / furnace, and the basicity of the final slag of refining is 0.75 to 0.79;

[0053] (9) After the refining soft blowing is completed, the slag is removed by a car-type slag removal machine after steel is tapped. During the slag removal process, the ladle bottom blowing is turned off and the removed slag is placed in an empty slag basin;

[0054] (10) The ladle baking equipment is used to fully bake and dry the slag in the slag basin, and the baking time is 47 minutes;

[0055] (11) The dried slag was weighed, and the total weight of the slag from the seven furnaces was 2023.39 kg. 26.3 kg of quicklime was added for every 300 kg of the weight. The slag was crushed in an industrial crusher and stirred thoroughly to obtain 2200.77 kg of new refined slag;

[0056] (12) The composition of the newly refined slag sample was analyzed. The composition was CaO: 37.8%, SiO2: 36.0%, Al2O3: 2.83%, MgO: 17.6%, MnO: 1.26%, TiO2: 0.24%, and the other components were all ≤ 0.04%. The basicity was 1.05, which met the requirements of cord steel refined slag. CaO: 35.0%~43.0%, SiO2: 35.0%~38.0%, Al2O3:

[0057] 1.80%~3.50%, MgO: 12.0%~20.0%, MnO≤2.00%, TiO2≤0.50%, other components are all ≤0.08%, basicity 0.95~1.15.

[0058] The chemical composition of 55SiCr in 7 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.53~0.57%, Si: 1.35~1.47%, Mn: 0.58~0.75%, Cr: 0.55~0.78%, P≤0.018%, S≤0.016%, Ni≤0.05%, Cu≤0.05%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0059] Example 2

[0060] In actual production, 16 furnaces of 55SiCr were smelted in pouring 2. The specific operation steps are as follows:

[0061] (1) The 1# and 3# 120t top and bottom composite blowing converters were used for batching, and 90.5-94.5 tons of desulfurized iron water and 25.0-29.0 tons of pig iron were added for primary smelting in the converters;

[0062] (2) Low aluminum-magnesium-carbon steel ladles are used for converter smelting, and internal refractory materials are sampled and analyzed in advance, with MgO: 88.47% to 89.75%, Al2O3: 0.25% to 0.38%;

[0063] (3) After 36.7-38.5 tons of molten steel was discharged from the converter, alloys were added. First, 2478-2755 kg / furnace of low-titanium and low-aluminum ferrosilicon was added, then 1345-1433 kg / furnace of low-carbon ferrochrome was added, and finally 609-657 kg / furnace of metallic manganese was added. The three types of alloys were sampled and analyzed in advance, among which the Al content was 0.006%-0.015% and the Ti content was 0.008%-0.014%;

[0064] (4) The converter uses a slide plate and a slag cone to block slag. The molten steel is left to stand for 3.3 to 4.5 seconds before the slide plate is opened to release the steel. No slag is discharged.

[0065] (5) After the converter is tapped, a car-type slag remover is used to remove slag. During the slag removal process, argon is blown from the bottom of the ladle at a flow rate of 112 to 170 L / min. Visually, there is no residue on the surface of the molten steel and the slag is removed cleanly;

[0066] (6) Before refining, 1000 kg of spring steel special refined slag with the following components added into each ladle: CaO: 46.6% to 54.2%, SiO2: 43.8% to 49.5%, Al2O3: 0.19% to 0.26%, MgO: 1.06% to 1.38%, MnO: 0.025% to 0.057%, TiO2: 0.048% to 0.072%, other components ≤ 0.035%, basicity 0.94 to 1.24;

[0067] (7) During the refining process, 280-421 kg / furnace of low-titanium and low-aluminum ferrosilicon, 260-282 kg / furnace of low-carbon ferrochrome, and 190-225 kg / furnace of metallic manganese were added. The three types of alloys were sampled and analyzed in advance, with Al content of 0.019%-0.028% and Ti content of 0.022%-0.026%.

[0068] (8) The refining process lasts 30.0 to 35.4 minutes, the argon blowing of the ladle is controlled at 258 to 298 NL / min, and soft blowing is performed at the end of refining, the soft blowing time is 25.5 to 28.5 minutes, the argon blowing of the ladle is controlled at 135 to 150 NL / min, 80 to 98 kg of quicklime is added per furnace, and the basicity of the final slag of refining is 0.72 to 0.78;

[0069] (9) After the refining soft blowing is completed, the slag is removed by a car-type slag removal machine after steel is tapped. During the slag removal process, the ladle bottom blowing is turned off and the removed slag is placed in an empty slag basin;

[0070] (10) The slag in the slag basin is fully baked and dried using a ladle baking device, and the baking time is 48 minutes;

[0071] (11) The dried slag was weighed, and the total weight of slag from 16 furnaces was 4665.6 kg. 25.8 kg of quicklime was added for every 300 kg of the weight. The slag was crushed in an industrial crusher and stirred thoroughly to obtain 5066.84 kg of new refined slag;

[0072] (12) The composition of the newly refined slag sample was analyzed. The composition was CaO: 38.9%, SiO2: 36.4%, Al2O3: 2.24%, MgO: 15.6%, MnO: 1.11%, TiO2: 0.36%, and the other components were all ≤ 0.06%. The basicity was 1.07, which met the requirements of cord steel refined slag. CaO: 35.0%~43.0%, SiO2: 35.0%~38.0%, Al2O3:

[0073] 1.80%~3.50%, MgO: 12.0%~20.0%, MnO≤2.00%, TiO2≤0.50%, other components are all ≤0.08%, basicity 0.95~1.15.

[0074] The chemical composition of 55SiCr in 16 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.53~0.56%, Si: 1.35~1.45%, Mn: 0.58~0.68%, Cr: 0.57~0.73%, P≤0.015%, S≤0.012%, Ni≤0.03%, Cu≤0.03%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0075] Example 3

[0076] In actual production, three castings were performed to smelt three furnaces of 55SiCr. The specific operation steps are as follows:

[0077] (1) A 2#120t top and bottom composite blowing converter was used for batching, and 90.7-92.8 tons of desulfurized hot metal and 27.5-29.3 tons of clean scrap steel were added for primary smelting in the converter;

[0078] (2) Low-aluminum-magnesium-carbon steel ladles are used for converter smelting, and internal refractory materials are sampled and analyzed in advance, with MgO: 85.47% to 86.89%, Al2O3: 0.28% to 0.94%;

[0079] (3) After 39.0-41.0 tons of molten steel was discharged from the converter, alloys were added. First, 2457-2716 kg / furnace of low-titanium and low-aluminum ferrosilicon was added, then 1366-1412 kg / furnace of low-carbon ferrochrome was added, and finally 611-644 kg / furnace of metallic manganese was added. The three types of alloys were sampled and analyzed in advance, among which the Al content was 0.008%-0.015% and the Ti content was 0.006%-0.013%;

[0080] (4) The converter uses a slide plate and a slag cone to block slag. The molten steel is left to stand for 3.2 to 4.3 seconds before the slide plate is opened to release the steel. No slag is discharged.

[0081] (5) After the converter is tapped, a car-type slag remover is used to remove slag. During the slag removal process, argon is blown from the bottom of the ladle at a flow rate of 155 to 195 L / min. Visually, there is no residue on the surface of the molten steel and the slag is removed cleanly;

[0082] (6) Before refining, 1000 kg of spring steel special refined slag with the following components added into each ladle: CaO: 45.8% to 53.2%, SiO2: 44.8% to 47.5%, Al2O3: 0.22% to 0.26%, MgO: 1.16% to 1.37%, MnO: 0.031% to 0.067%, TiO2: 0.052% to 0.069%, other components ≤ 0.04%, basicity 0.96 to 1.19;

[0083] (7) During the refining process, 280-305 kg / furnace of low-titanium and low-aluminum ferrosilicon, 260-275 kg / furnace of low-carbon ferrochrome, and 186-231 kg / furnace of metallic manganese were added. The three types of alloys were sampled and analyzed in advance, with Al content of 0.015%-0.018% and Ti content of 0.024%-0.026%.

[0084] (8) The refining process lasts 31.0 to 35.0 minutes, the argon blowing of the ladle is controlled at 255 to 285 NL / min, and soft blowing is performed at the end of refining, the soft blowing time is 26 to 28 minutes, the argon blowing of the ladle is controlled at 146 to 155 NL / min, 80 to 85 kg of quicklime is added per furnace, and the basicity of the final slag of refining is 0.72 to 0.75;

[0085] (9) After the refining soft blowing is completed, the slag is removed by a car-type slag removal machine after steel is tapped. During the slag removal process, the ladle bottom blowing is turned off and the removed slag is placed in an empty slag basin;

[0086] (10) The slag in the slag basin is fully baked and dried using a ladle baking device, and the baking time is 46 minutes;

[0087] (11) The dried slag was weighed, and the total weight of the slag from the three furnaces was 915.9 kg. 26.7 kg of quicklime was added for every 300 kg of the weight. The slag was crushed in an industrial crusher and stirred thoroughly to obtain 997.4 kg of new refined slag.

[0088] (12) The fresh refined slag sample was analyzed and the composition was CaO: 40.5%, SiO2: 38.5%, Al2O3: 2.54%, MgO: 17.3%, MnO: 1.28%, TiO2: 0.18%, and other components were ≤ 0.05%, and the basicity was 1.05, which met the requirements of cord steel refined slag: CaO: 35.0%~43.0%, SiO2: 35.0%~38.0%, Al2O3:

[0089] 1.80%~3.50%, MgO: 12.0%~20.0%, MnO≤2.00%, TiO2≤0.50%, other components are all ≤0.08%, basicity 0.95~1.15.

[0090] The chemical composition of the 3rd furnace of 55SiCr in this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.53~0.56%, Si: 1.35~1.42%, Mn: 0.58~0.62%, Cr: 0.57~0.71%, P≤0.016%, S≤0.011%, Ni≤0.05%, Cu≤0.04%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0091] Example 4

[0092] In actual production, 5 furnaces of 55SiCr were smelted in 4 castings. The specific operation steps are as follows:

[0093] (1) A 2#120t top and bottom composite blowing converter was used for batching, and 90.2-97.4 tons of desulfurized hot metal and 24.3-28.9 tons of clean scrap steel were added for primary smelting in the converter;

[0094] (2) Low-aluminum-magnesium-carbon steel ladles are used for converter smelting, and the internal refractory materials are sampled and analyzed in advance, with MgO: 86.59% to 87.54%, Al2O3: 0.24% to 0.31%;

[0095] (3) After 36-37 tons of molten steel was discharged from the converter, alloys were added. First, 2453-2694 kg / furnace of low-titanium and low-aluminum ferrosilicon was added, then 1346-1399 kg / furnace of low-carbon ferrochrome was added, and finally 603-658 kg / furnace of metallic manganese was added. The three types of alloys were sampled and analyzed in advance, among which the Al content was 0.007%-0.011% and the Ti content was 0.004%-0.010%;

[0096] (4) The converter uses a slide plate and a slag cone to block slag. The molten steel is left to stand for 3.6 to 4.7 seconds before the slide plate is opened to release the steel. No slag is discharged.

[0097] (5) After the converter is tapped, a car-type slag remover is used to remove slag. During the slag removal process, argon is blown from the bottom of the ladle at a flow rate of 140 to 157 L / min. Visually, there is no residue on the surface of the molten steel and the slag is removed cleanly;

[0098] (6) Before refining, 1000 kg of spring steel special refined slag with the following components added into each ladle: CaO: 45.6% to 53.7%, SiO2: 43.5% to 49.8%, Al2O3: 0.27% to 0.32%, MgO: 1.27% to 1.41%, MnO: 0.043% to 0.067%, TiO2: 0.035% to 0.066%, other components ≤ 0.035%, basicity 0.91 to 1.23;

[0099] (7) During the refining process, 282-443 kg / furnace of low-titanium and low-aluminum ferrosilicon, 254-277 kg / furnace of low-carbon ferrochrome, and 184-256 kg / furnace of metallic manganese were added. The three types of alloys were sampled and analyzed in advance, with Al content of 0.020%-0.024% and Ti content of 0.023%-0.025%.

[0100] (8) The refining process lasts 32.5 to 36.5 minutes, the argon blowing of the ladle is controlled at 295 to 305 NL / min, and soft blowing is performed at the end of refining, the soft blowing time is 26.5 to 31.50 minutes, the argon blowing of the ladle is controlled at 120 to 135 NL / min, 85 to 100 kg of quicklime is added per furnace, and the basicity of the final slag of refining is 0.76 to 0.80;

[0101] (9) After the refining soft blowing is completed, the slag is removed by a car-type slag removal machine after steel is tapped. During the slag removal process, the ladle bottom blowing is turned off and the removed slag is placed in an empty slag basin;

[0102] (10) The ladle baking equipment is used to fully bake and dry the slag in the slag basin, and the baking time is 53 minutes;

[0103] (11) The dried slag was weighed. The total weight of the slag from the five furnaces was 1446.5 kg. 26.6 kg of quicklime was added for every 300 kg of the weight. The slag was crushed in an industrial crusher and stirred thoroughly to obtain 1574.76 kg of new refined slag.

[0104] (12) The fresh refined slag sample was analyzed and the composition was CaO: 38.3%, SiO2: 37.2%, Al2O3: 2.63%, MgO: 16.4%, MnO: 1.33%, TiO2: 0.14%, and other components were ≤ 0.05%, and the basicity was 1.03, which met the requirements of cord steel refined slag: CaO: 35.0%~43.0%, SiO2: 35.0%~38.0%, Al2O3:

[0105] 1.80%~3.50%, MgO: 12.0%~20.0%, MnO≤2.00%, TiO2≤0.50%, other components are all ≤0.08%, basicity 0.95~1.15.

[0106] The chemical composition of 55SiCr in 5 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.54~0.57%, Si: 1.37~1.45%, Mn: 0.59~0.73%, Cr: 0.57~0.75%, P≤0.015%, S≤0.014%, Ni≤0.04%, Cu≤0.05%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0107] Comparative Example 1

[0108] In actual production, 5 castings were made to smelt 7 furnaces of 55SiCr. Ordinary aluminum ladle was used for smelting. The ladle refractory MgO: 79.55% ~ 81.13%, Al2O3: 8.21% ~ 9.36%. Other process parameters and operations were carried out with reference to Example 1. 2112.6 kg of slag was recovered. The sampling and analysis of the components showed that CaO: 37.8%, SiO2: 37.0%, Al2O3: 5.54%, MgO: 5.90%, MnO: 1.68%, Ti O2: 0.41%, other components are ≤0.05%, basicity is 1.02, among which Al2O3: 5.54%, MgO: 5.90% do not meet the requirements of cord steel refined slag Al2O3: 1.80%~3.50%, MgO: 12.0%~20.0%. If this type of refined slag continues to be used in cord steel production, it will cause an increase in Al2O3-type high-melting point hard inclusions, which will cause the cord production drawing fracture, resulting in the slag recovered in this casting cannot be recycled.

[0109] The chemical composition of 55SiCr in 7 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.54~0.57%, Si: 1.37~1.42%, Mn: 0.58~0.63%, Cr: 0.62~0.71%, P≤0.015%, S≤0.008%, Ni≤0.03%, Cu≤0.04%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0110] Comparative Example 2

[0111] In the actual production, 6 castings were made to smelt 16 furnaces of 55SiCr. Low-titanium and low-aluminum ferrosilicon, low-carbon ferrochrome, and metallic manganese were added during the converter and refining process. The Al content was 0.030% to 0.042%, and the Ti content was 0.032% to 0.045%. The other process parameters and operations were carried out with reference to Example 2. 4636.8 kg of slag was recovered, and the sampling and analysis of the components showed that CaO: 38.9%, SiO2: 38.7%, Al2O3: 4.46%, MgO: 12.90%, and MnO: 1 .46%, TiO2: 2.56%, other components are all ≤0.05%, basicity is 1.00, among which Al2O3: 4.46%, TiO2: 2.56% do not meet the requirements of cord steel refined slag Al2O3: 1.80% ~ 3.50%, TiO2 ≤ 0.50%. If this type of refined slag continues to be used in cord steel production, it will cause an increase in Al2O3, TiO2 and other high melting point hard inclusions, which will cause the cord production drawing fracture, resulting in the slag recovered in this casting cannot be recycled.

[0112] The chemical composition of 55SiCr in 16 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.54~0.57%, Si: 1.37~1.42%, Mn: 0.58~0.63%, Cr: 0.62~0.71%, P≤0.015%, S≤0.008%, Ni≤0.03%, Cu≤0.04%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0113] Comparative Example 3

[0114] In actual production, 7 castings were made to smelt 3 furnaces of 55SiCr. After the refining soft blowing, 20-35 kg / furnace of quicklime was added. The basicity of the final slag was 0.55-0.65. The other process parameters and operations were carried out with reference to Example 3. 900.9 kg of slag was recovered. The components of the sample analysis were CaO: 20.9%, SiO2: 36.0%, Al2O3: 2.74%, MgO: 26.90%, MnO: 1.57%, TiO2: 0.2 6%, other components are ≤0.05%, basicity is 0.58, of which CaO: 20.9%, MgO: 26.90% do not meet the requirements of cord steel refined slag CaO: 35.0% ~ 43.0%, MgO: 12.0% ~ 20.0%. If this type of refined slag continues to be used in cord steel production, it will cause an increase in Mg-Si type high melting point hard olivine inclusions, which will cause the cord production drawing fracture, and the slag recovered in this casting cannot be recycled.

[0115] The chemical composition of the 3rd furnace of 55SiCr in this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.52~0.57%, Si: 1.34~1.44%, Mn: 0.59~0.62%, Cr: 0.67~0.71%, P≤0.013%, S≤0.010%, Ni≤0.03%, Cu≤0.03%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0116] Comparative Example 4

[0117] In actual production, 8 pouring times were performed to smelt 5 furnaces of 55SiCr. The converter used slide plates and slag cones to block slag. After the molten steel was left to stand for 1.3 seconds, the slide plates were opened to release the steel. Slag appeared. Other process parameters and operations were carried out with reference to Example 3. 1556.5 kg of slag was recovered. The components of the sample analysis were CaO: 35.6%, SiO2: 36.2%, Al2O3: 11.75%, MgO: 37.80%, MnO: 1.77%, TiO2 : 0.38%, other components are ≤0.05%, basicity is 0.98, among which Al2O3: 11.75%, MgO: 37.80% do not meet the requirements of cord steel refined slag Al2O3: 1.80% ~ 3.50%, MgO: 12.0% ~ 20.0%. If this type of refined slag continues to be used in cord steel production, it will cause an increase in Mg-Al spinel inclusions and cause the cord production drawing fracture. The slag recovered in this casting cannot be recycled.

[0118] The chemical composition of 55SiCr in 5 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.55-0.59%, Si: 1.35-1.47%, Mn: 0.56-0.64%, Cr: 0.63-0.72%, P≤0.018%, S≤0.016%, Ni≤0.05%, Cu≤0.05%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0119] Comparative Example 5

[0120] In actual production, 9 castings were made to smelt 7 furnaces of 55SiCr. Ordinary aluminum ladle was used for smelting. The ladle refractory MgO was 77.56% to 83.43%, Al2O3 was 7.42% to 10.06%, and low-titanium and low-aluminum ferrosilicon, low-carbon ferrochrome, and metallic manganese were added during the converter and refining process. The Al content was 0.055% to 0.070%, and the Ti content was 0.035% to 0.047%. No quicklime was added at the end of the refining soft blowing. The basicity of the final slag was 0.57 to 0.68. The other process parameters and operations were carried out with reference to Example 1. 2186.8 kg of slag was recovered, and the components of CaO and SiO2 were sampled and analyzed. %, Al2O3: 9.74%, MgO: 22.87%, MnO: 1.44%, TiO2: 0.36%, other components are all ≤0.05%, basicity 0.61, among which Al2O3: 9.74%, MgO: 22.87%, basicity 0.61 do not meet the requirements of cord steel refined slag Al2O3: 1.80%~3.50%, MgO: 12.0%~20.0%, basicity 0.99~1.08. If this type of refined slag continues to be used in cord steel production, it will cause an increase in Mg-Al high melting point hard olivine inclusions, which will cause the cord production drawing fracture, and the slag recovered in this casting cannot be recycled.

[0121] The chemical composition of 55SiCr in 7 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.52~0.58%, Si: 1.38~1.45%, Mn: 0.55~0.62%, Cr: 0.58~0.68%, P≤0.012%, S≤0.010%, Ni≤0.05%, Cu≤0.06%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0122] Comparative Example 6

[0123] In actual production, 10 pouring times and 16 furnaces of 55SiCr were smelted. The converter used a slide plate and a slag cone to block the slag. After the molten steel was left to stand for 1.2 to 2.0 seconds, the slide plate was opened to release the steel. Slag was discharged. After the converter was tapped, a car-type slag remover was used to remove the slag. During the slag removal process, argon was blown from the bottom of the ladle. The bottom blowing flow rate was 254 to 303 L / min. It was visually observed that there was slag residue on the surface of the molten steel and slag curling. Other process parameters and operations were referred to the embodiment. 2, 5057.6kg of slag was recovered, and the sample analysis components were CaO: 36.7%, SiO2: 35.5%, Al2O3: 12.02%, MgO: 28.64%, MnO: 1.75%, TiO2: 0.31%, and other components were ≤ 0.05%, basicity 1.03, of which Al2O3: 12.02%, MgO: 28.64% did not meet the requirements of cord steel refining slag Al2O3:

[0124] 1.80%~3.50%, MgO: 12.0%~20.0% requirements. If this type of refined slag continues to be used in the production of cord steel, it will cause an increase in Mg-Al spinel inclusions, which will cause the cord production to break during drawing, and the slag recovered in this casting cannot be recycled.

[0125] The chemical composition of 55SiCr in 16 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.52~0.57%, Si: 1.28~1.40%, Mn: 0.55~0.64%, Cr: 0.55~0.70%, P≤0.020%, S≤0.014%, Ni≤0.05%, Cu≤0.04%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0126] Comparative Example 7

[0127] In actual production, 11 castings were made to smelt 5 furnaces of 55SiCr. Before refining, the following components were added to each ladle: CaO: 45.6%~53.7%, SiO2: 13.5%~19.8%, Al2O3: 4.27%~6.32%, MgO: 4.27%~8.41%, MnO: 0.043%~0.067%, TiO2: 0.035%~0.040%, and other components were all ≤0.035%, basicity 2. 03~3.98 Ordinary 45 steel refined slag 1000kg, refining process 33.5~36.0min, ladle argon blowing control 400~415NL / min, soft blowing at the end of refining, soft blowing time 26.5~31.5min, ladle argon blowing control 180~205NL / min, add quicklime 120~135kg / furnace at the end of refining soft blowing, final slag basicity 2.05~4.33, other process parameters The number and operation are all carried out according to Example 4, and 900.9 kg of slag is recovered. The sampling and analysis of the components are CaO: 44.5%, SiO2: 15.4%, Al2O3: 12.74%, MgO: 17.90%, MnO: 1.59%, TiO2: 0.38%, and the other components are all ≤ 0.06%, and the basicity is 2.89, including CaO: 44.5%, SiO2: 15.4%, Al2O3: 12.74%, The basicity of 2.89 does not meet the requirements of cord steel refined slag to meet the requirements of cord steel refined slag: CaO: 35.0%~43.0%, SiO2: 35.0%~38.0%, Al2O3: 1.80%~3.50%, basicity 0.95~1.15. If this type of refined slag continues to be used in cord steel production, it will cause an increase in large-sized CA-Si-Al oxide inclusions, which will cause the cord production to break during drawing. The slag recovered in this casting cannot be recycled.

[0128] The chemical composition of 55SiCr in 5 furnaces of this casting is calculated according to mass percentage. The actual composition at the end of LF is C: 0.53~0.59%, Si: 1.35~1.45%, Mn: 0.55~0.67%, Cr: 0.62~0.69%, P≤0.016%, S≤0.013%, Ni≤0.06%, Cu≤0.06%, and the rest is iron and unavoidable impurities, which meets the internal control requirements of smelting composition.

[0129] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A slag blending method for recycling spring steel 55SiCr refined slag, characterized in that: The method comprises the following steps: (1) A 120 t top and bottom composite blowing converter is used and 70-90% by weight of desulfurized iron water is added, and the rest is clean scrap steel or pig iron as raw materials for primary smelting in the converter; (2) The refractory materials inside the ladle used in the smelting process must meet the requirements of MgO ≥ 85.0% and Al2O3 ≤ 1.0%; (3) The converter alloy begins to be charged after 1 / 3 of the molten steel has been tapped, first adding low-titanium and low-aluminum ferrosilicon, then low-carbon ferrochrome, and finally adding metallic manganese, and the Al and Ti contents in the alloy are ≤0.015%; (4) The converter uses a slide plate and a slag cone to block the slag. After the molten steel is left to stand, the slide plate is opened to release the steel. (5) After the converter is tapped, the slag is removed by a slag remover, and the ladle bottom must be blown to remove the slag; (6) Before refining, the ladle is added with the following components: CaO: 45.0% to 55.0%, SiO2: 43.0% to 50.0%, Al2O3≤0.36%, MgO≤1.45%, MnO, TiO2≤0.08%, other components are all ≤0.06%, basicity is 0.90 to 1.28, and the special refining slag for spring steel 55SiCr wire rod is added at 1000kg / furnace; (7) During the refining process, low-titanium and low-aluminum ferrosilicon, low-carbon ferrochrome, and metallic manganese are added, and the Al and Ti contents in the alloy are 0.015% to 0.030%; (8) The refining process is ≥30min, the ladle is purged with argon throughout the process, soft blowing is performed at the end of refining, the ladle is purged with argon throughout the process, quicklime is added, and the basicity of the final slag is controlled at 0.70-0.80; (9) After the refining soft blowing is completed, the slag is removed by the slag removal machine after the steel is tapped. During the slag removal process, the ladle bottom blowing is turned off and the removed slag is placed in an empty slag basin; (10) Using ladle baking equipment to fully bake and dry the slag in the slag basin; (11) After drying, 25 to 30 kg of quicklime is added to every 300 kg of the slag, which is poured into an industrial crusher and crushed and stirred thoroughly to obtain a new refined slag with the composition of CaO: 35.0% to 40.0%, SiO2: 35.0% to 37.0%, Al2O3: 1.80% to 3.40%, MgO: 12.0% to 19.0%, MnO ≤ 1.80%, TiO2 ≤ 0.40%, and other components ≤ 0.06%, and the basicity of 0.99 to 1.08, which is suitable for cord steel.

2. The slag blending method for recycling spring steel 55SiCr refined slag according to claim 1, characterized in that: The chemical composition of the spring steel 55SiCr wire rod is calculated by mass percentage, and the ratio is C: 0.51-0.59%, Si: 1.20-1.60%, Mn: 0.50-0.80%, Cr: 0.50-0.80%, P≤0.025%, S≤0.020%, Ni≤0.35%, Cu≤0.25%, and the rest is iron and unavoidable impurities.

3. The slag blending method for recycling spring steel 55SiCr refined slag according to claim 1, characterized in that: In the step (3), the converter alloy starts to be added after 1 / 3 of the molten steel has been tapped, first adding 2400-2800 kg / furnace of low-titanium and low-aluminum ferrosilicon, then adding 1300-1500 kg / furnace of low-carbon ferrochrome, and finally adding 600-700 kg / furnace of metallic manganese.

4. The slag blending method for recycling spring steel 55SiCr refined slag according to claim 1, characterized in that: In the step (5), after the converter is tapped, a slag remover is used to remove slag. The ladle must be bottom blown for slag removal, and the bottom blowing flow rate is ≤200L / min.

5. The slag blending method for recycling spring steel 55SiCr refined slag according to claim 1, characterized in that: In the refining process of step (7), 270-600 kg / furnace of low-titanium and low-aluminum ferrosilicon, 230-300 kg / furnace of low-carbon ferrochrome, and 160-300 kg / furnace of metallic manganese are added.

6. The slag blending method for recycling spring steel 55SiCr refined slag according to claim 1, characterized in that: The refining process of step (8) is ≥30min, the ladle is argon-blown throughout the process, and the argon blowing flow rate is 290-350NL / min. After the refining is completed, soft blowing is performed, and the soft blowing time is ≥25min. The ladle is argon-blown throughout the process, and the argon blowing flow rate is ≤180NL / min. 80-120kg / furnace of quicklime is added.

7. The slag blending method for recycling spring steel 55SiCr refined slag according to claim 1, characterized in that: The baking time in step (10) is ≥45 min.