A refining slag-removing agent, preparation method and smelting method for low-carbon steel wire

Abstract

The present invention relates to a refining slag-forming agent, a preparation method and a smelting method applied to low-carbon steel wire rods. Waste slag and waste magnesium carbon bricks generated in the aluminum-killed steel refining process are used as main raw materials, which are mixed and crushed in a certain proportion to form a refining slag-forming agent that can be used for low-carbon steel wire rods and has anti-ladle erosion performance. The smelting method performs secondary deoxidation and modification on the refined slag through a reasonable feeding method, and designs a CaO-Al2O3-SiO2-MgO quaternary refining slag system with a high MgO content, which replaces the original CaO-SiO2 slag system. The present invention can not only meet the requirements of low-cost and pollution-free products, but also realize the metallurgical functions of refining rapid slag-forming, desulfurization and reducing the erosion of ladle refractory materials.

Description

Technical Field

[0001] The invention relates to a refining slag-removing agent, a preparation method and a smelting method applied to low-carbon steel wire, belonging to the technical field of metallurgy, in particular to the technical field related to steelmaking and refining control. Background Art

[0002] Low-carbon steel wire is mainly made of silicon-killed steel. The typical process route for smelting low-carbon steel wire is electric furnace / converter smelting → ladle refining → continuous casting. The main feature of the refining process is the high oxidizing property of the slag. The high oxidizing property of the slag has a significant effect on the erosion of the ladle refractory material and is not conducive to the desulfurization reaction. In order to ensure that the sulfur content of the molten steel meets the standard, the refining and slag making of low-carbon steel wire is mainly based on the high-basicity CaO-SiO2 desulfurization slag system. Therefore, in the refining process of low-carbon steel wire, fluorite is usually added to quickly melt the high-melting-point CaO-SiO2 slag to achieve rapid desulfurization. For example, application CN202211364600.7 discloses a rapid smelting method for low-carbon aluminum-free deoxidized low-sulfur steel. The process method requires the addition of 300-360kg of fluorite balls during the refining process to improve the fluidity of the slag, achieve rapid desulfurization, and shorten the smelting cycle.

[0003] Unlike high-carbon steel, the molten steel and slag in the ladle refining process of low-carbon steel are highly oxidizing, which will further aggravate the erosion behavior of the ladle refractory materials. Therefore, in order to reduce the erosion of the ladle refractory materials, the dissolution of MgO in the refractory materials is reduced by adding lightly burned magnesium oxide balls to increase the MgO content in the slag. For example, application CN202210172431.0 discloses a method for reducing the erosion rate of the ladle slag line in the production of rebar. This technical method uses electric molten pre-melted slag to replace fluorite, which improves the slag-melting speed and top slag foaming performance, and then reduces the erosion of the ladle slag line by adding 100-120kg of lightly burned magnesium oxide balls and 60-100kg of quartz sand.

[0004] As for fluorite, it is a non-renewable resource with a high price. The technical method of using a large amount of fluorite to achieve rapid refining and slagging has the problems of high slagging cost and large pollution of fluorine-containing solid waste. Moreover, under the combined action of fluorite and oxidizing slag, the erosion rate of ladle refractory is relatively fast, resulting in increased refractory cost and reduced cleanliness of molten steel. Using pre-melted slag to replace fluorite to assist in slagging, and adding additional auxiliary materials such as lightly burned magnesium oxide balls and quartz sand, although it can reduce the erosion rate of refractory to a certain extent, this method increases the viscosity of the slag, reduces the basicity, and worsens the desulfurization effect, making it difficult to meet quality control requirements. At the same time, it will further increase the cost of refining and slagging, which is not conducive to reducing costs and increasing efficiency.

[0005] Therefore, the smelting of low-carbon steel wire requires a low-cost, pollution-free refining slag-removing agent to achieve rapid slag-removing and desulfurization and avoid the problem of rapid erosion of ladle refractory materials. Summary of the invention

[0006] The present invention provides a refining slag-forming agent, a preparation method and a smelting method applied to low-carbon steel wire, which can not only meet the requirements of low-cost and pollution-free products, but also achieve the metallurgical functions of refining rapid slag-forming, desulfurization and reducing the erosion of ladle refractory materials.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] A refining slag-reducing agent comprises aluminum killed steel refining waste slag and waste magnesium carbon bricks, wherein the mixing ratio of the two is aluminum killed steel refining waste slag: waste magnesium carbon bricks = 8:2-9:1 in terms of mass percentage;

[0009] Wherein, in the aluminum killed steel refining waste slag, S≤0.3% and SiO2<3% by mass percentage;

[0010] The waste magnesia carbon bricks contain MgO≥60% by mass, C is 5-15%, and the rest is CaO and other inevitable impurities;

[0011] Furthermore, the main components of the refining slag-forming agent include, by mass percentage, 50-55% CaO, 25-30% Al2O3, 10-15% MgO, the total amount of FeO and MnO ≤0.5%, SiO2 ≤3%, C 0.8-2%, S ≤0.1%;

[0012] After the aluminum killed steel refining waste slag and the waste magnesia carbon bricks are mixed, the total amount of 12CaO•7Al2O3 and 3CaO•Al2O3 in the mineral phase composition of the mixture is ≥65%, and the hemispherical point temperature is ≤1380℃;

[0013] The preparation method of the refining slag-removing agent specifically comprises the following steps:

[0014] The first step is to pour the molten aluminum killed steel refining waste slag into a mixed slag tank, and then spray the waste magnesium carbon brick particles into it, mix them thoroughly and then cool them naturally;

[0015] Step 2: Repeat the steps in step 1 until the slag tank is filled with mixed slag;

[0016] In the third step, the mixed slag cooled to room temperature in the slag tank is poured out, and is crushed and iron-removed in two stages to form powder slag, which is then screened and the powder slag that meets the screening standards is loaded into the raw material bin;

[0017] The fourth step is to start a roller press in the raw material bin to dry-press the powder slag into pillow-shaped slag balls, which are the refining slag-reducing agent;

[0018] Furthermore, in the first step, the particle size of the waste magnesia carbon brick particles is 1-5 mm;

[0019] The single mixing amount of aluminum killed steel refining waste slag and waste magnesia carbon bricks is ≤800kg, and the pre-mixing temperature is set to ≥1200℃.

[0020] After thorough mixing, the cooling time is set to last 30-40 minutes;

[0021] Furthermore, in the third step, the screening standard is that, by mass percentage, the proportion of powder residue particle size ≤3 mm is greater than or equal to 90%, and the proportion of powder residue particle size >6 mm is less than 3%;

[0022] In the fourth step, the roller press pressure is set to 2500-3000MPa, the minimum gap between the extrusion rollers is ≤2mm, the forced feeding process is adopted, and the feeding speed is set to 50-60kg / min;

[0023] The smelting method of applying the refining slag-reducing agent to low-carbon steel wire rod specifically comprises the following steps:

[0024] Step S1, after the electric furnace / converter smelting is completed, steel is tapped. When the tapping reaches 1 / 3 of the total amount, silicon-manganese alloy, ferrosilicon, carbon powder and active lime are added to the molten steel in sequence. After the tapping is completed, a refining slag-removing agent is added to the slag surface, and bottom blowing and stirring of the ladle behind the furnace are started at the same time;

[0025] Step S2, the ladle enters the refining process, samples the molten steel and measures its temperature, then adds lime, starts refining bottom blowing and stirring, and then inserts electrodes to energize and heat.

[0026] Step S3, after the heating is completed, stir in vain for 3-5 minutes, add the refining slag agent for the second time, and add silicon-manganese alloy, ferrosilicon and carbon powder according to the measured molten steel composition to adjust the molten steel composition to the target composition range, then add calcium carbide to the slag surface, and enter step S4 after soft stirring;

[0027] Step S4, entering the continuous casting process, using a small square billet continuous casting machine with a cross section of 150mm×150mm to pour molten steel, and protecting the pouring process throughout the process;

[0028] Furthermore, in step S1, the amount of silicon manganese alloy added is 1.6-1.8 kg / t, the amount of ferrosilicon added is 2-3 kg / t, the amount of carbon powder added is 0-1.5 kg / t, the amount of active lime added is 2-2.5 kg / t, and the amount of refining slag-forming agent added is 1.5-2 kg / t;

[0029] After the furnace is turned on, the gas flow rate of the ladle bottom blowing and stirring is 600-800NL / min, and the stirring time lasts for 8-10min;

[0030] Further, in step S2, the amount of lime added is 1-3 kg / t;

[0031] The gas flow rate for refining bottom blowing and stirring is 400-600NL / min;

[0032] Further, in step S3, the gas flow rate of bottom blowing with air stirring is 600-800NL / min, the secondary addition amount of refining slag agent is 0.5-1kg / t, the addition amount of calcium carbide is 0.4-0.6kg / t, the gas flow rate of soft stirring is 150-200NL / min, and the soft stirring time lasts for 5-8min;

[0033] Furthermore, in step S4, during the whole protection casting process, the superheat of molten steel is set to 20-30°C, the continuous casting billet drawing speed is set to 2.5-3.5m / min, and the secondary cooling water volume is set to 1.1-1.5L / kg.

[0034] Through the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The refining slag-removing agent provided by the present invention uses aluminum-killed steel refining waste slag and waste magnesium carbon bricks produced in the steel manufacturing process as raw materials, has low cost, does not contain fluoride in its composition, and will not cause fluoride pollution problems when used; the slag-removing agent contains a high mass fraction of low-melting point phases 12CaO•7Al2O3 and 3CaO•Al2O3 in its physical phase composition, and after use, it can transform the refining slag from the original CaO-SiO2 slag system into the CaO-Al2O3-SiO2-MgO slag system, thereby realizing rapid refining slag-removing and desulfurization;

[0036] 2. The refining slag-reducing agent provided by the present invention has a relatively high content of MgO and some residual carbon. After use, the MgO in the refined slag can be increased to a reasonable range. Combined with the partial deoxidation and modification of the slag in the subsequent smelting method, the erosion rate of the ladle refractory material can be reduced;

[0037] 3. The preparation method of the refining slag-reducing agent provided by the present invention is based on cheap and readily available raw materials, and uses the residual heat of the refining waste slag to complete the slag modification, and then crushes and pelletizes the slag, which has a short processing flow and low energy consumption;

[0038] 4. The present invention provides a smelting method for low-carbon steel wire using a refining slag-forming agent. Based on the provided refining slag-forming agent, residual carbon is used for deoxidation and modification. The deoxidation product is gaseous carbon oxides, which have no adverse effects on the slag and molten steel. The secondary deoxidation and modification technology for silicon-killed steel slag can be realized, thereby improving the desulfurization capacity of the refined slag. DETAILED DESCRIPTION

[0039] The present invention is now described in further detail. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the protection scope of the present invention.

[0040] As described in the background technology, in order to reduce the process cost, most of the existing low-carbon steel wire smelting process methods adopt the process route of electric furnace / converter smelting → ladle refining → continuous casting; in the ladle refining process of this process method, the main refining slag target is to produce a high-basicity CaO-SiO2 slag system, which can achieve the functions of molten steel desulfurization and specific inclusion removal. However, there are two problems with this process method: (1) The molten steel and slag in the early stage of ladle refining are highly oxidizing and a large amount of fluorite is used in the refining slag process, which will lead to accelerated erosion of the ladle refractory material and shorten the life of the ladle. (2) Fluorite is a non-renewable natural mineral resource with high price. When used as a slag-reducing agent, it may cause excessive fluoride in the slag, causing environmental pollution. Although the use of pre-melted slag instead of lime and fluorite can also achieve rapid refining and slag-reduction, and will not cause fluorine-containing solid waste pollution, the pre-melted slag is generally made of a variety of pure minerals as raw materials, which are obtained by high-temperature melting and crushing and molding, and the cost is relatively high.

[0041] Based on this, the present application provides a refining slag-forming agent, a preparation method and a smelting method for low-carbon steel wire, which fully considers the requirements of low-cost and pollution-free products, and at the same time realizes the metallurgical functions of refining rapid slag-forming, desulfurization and reducing the erosion of refractory materials in the ladle.

[0042] First, as the first innovation of this application, a refining slag-forming agent is provided, which is mainly formed by processing the collected aluminum-killed steel refining waste slag and waste magnesium carbon bricks, thereby realizing the secondary utilization of aluminum-killed steel refining slag and waste magnesium carbon bricks. For aluminum-killed steel refining waste slag, the low melting point phases 12CaO•7Al2O3 and 3CaO•Al2O3 contained therein participate in refining and slag making, and can achieve the effect of fluxing and accelerating slag-forming. For waste magnesium carbon bricks, the MgO therein is used to increase the MgO content in the refining slag, thereby reducing the melting loss of MgO in the ladle refractory and achieving an anti-corrosion effect.

[0043] Why waste magnesia carbon bricks are used in the optimization? It is necessary to analyze the current status of the recycling of waste magnesia carbon bricks. The so-called magnesia carbon bricks are formed by pressing and sintering magnesia sand and graphite. High-quality magnesia carbon bricks are composed of fused magnesia sand and lamellar graphite. Fused magnesia sand is composed of large-sized MgO grains, with less impurities, strong refractoriness and corrosion resistance. Lamellar graphite greatly reduces the wettability of magnesia carbon bricks, thereby reducing the contact reaction between magnesia carbon bricks and high-temperature molten steel and slag. During the use of magnesia carbon bricks, due to long-term and repeated temperature fluctuations and the erosion of slag, the flake graphite in the magnesia carbon bricks is oxidized, the structure is destroyed, and the wettability of the magnesia carbon bricks is improved; the large-grained magnesia sand is melted and recrystallized, the grain size is reduced, the content of impurities at the grain boundaries is increased, and it no longer has good refractoriness and corrosion resistance. The industry recycles waste magnesia carbon bricks and directly mixes them into new magnesia carbon bricks after mechanical crushing. However, for the production conditions of this application, the product obtained by this process of recycling waste magnesia carbon bricks and mixing them into new coal cannot obtain good refractory properties, which is not conducive to improving the quality of new magnesia carbon bricks, thereby affecting the smelting effect.

[0044] The MgO particles and residual carbon in the waste magnesia carbon bricks, and the fine MgO grains can melt quickly after hot mixing and fully react with other components in the slag to form clinker with good metallurgical properties. The residual carbon (about 5-15%) in the prepared refining slag-reducing agent has a certain reducibility, which can achieve the deoxidation and modification of the refined slag, reduce the oxidizability of the slag, and achieve the effect of reducing slag erosion and improving desulfurization efficiency.

[0045] In order to achieve the best effect, first of all, regarding the components of the refining slag-reducing agent, the present application adopts a mixing ratio range of aluminum killed steel refining waste slag: waste magnesium carbon brick = 8:2-9:1 according to mass percentage; wherein, in the aluminum killed steel refining waste slag, S≤0.3% and SiO2<3% are measured by mass percentage; in the waste magnesium carbon brick, MgO≥60% and C is 5-15% according to mass percentage, and the rest are CaO and other unavoidable impurity components.

[0046] When the aluminum-killed steel refining waste slag and waste magnesia-carbon bricks are fully mixed, the main components thereof must also include, in terms of mass percentage, CaO of 50-55%, Al2O3 of 25-30%, MgO of 10-15%, the total amount of FeO and MnO ≤0.5%, SiO2≤3%, C of 0.8-2%, and S≤0.1%; in the mineral phase composition of the mixture, the total amount of 12CaO•7Al2O3 and 3CaO•Al2O3 is ≥65%, and the hemisphere point temperature is ≤1380℃.

[0047] The low melting point phases 12CaO•7Al2O3 and 3CaO•Al2O3 participate in refining and slag making, which can achieve the effect of fluxing and accelerating slag formation.

[0048] Then, based on the above chemical components and phase composition of the refining slag-removing agent, a method for preparing a refining slag-removing agent using waste magnesia carbon bricks to perform hot modification and cold processing on aluminum killed steel refining waste slag is provided, which specifically includes the following steps:

[0049] The first step is to pour the molten aluminum-killed steel refining waste slag into the mixing slag tank, and then spray the waste magnesium carbon brick particles (particle size is 1-5mm), mix them thoroughly and cool them naturally; before mixing, the temperature must be ≥1200℃, and the cooling time is set to last for 30-40 minutes after sufficient mixing.

[0050] In the second step, repeat the steps in the first step, with the single mixing amount ≤ 800kg, until the slag tank is filled with mixed slag.

[0051] In the third step, the mixed slag cooled to room temperature in the slag tank is poured out, and is crushed and iron-removed in two stages to form powder slag, which is then screened and loaded into the raw material bin if it meets the screening standards. The screening standards, i.e., the requirements for judging whether it is a qualified product, are that, in terms of mass percentage, the proportion of powder slag with a particle size of ≤3 mm is greater than or equal to 90%, and the proportion of powder slag with a particle size of >6 mm is less than 3%.

[0052] The fourth step is to set the roller press pressure to 2500-3000MPa in the raw material bin, the minimum gap between the extrusion rollers to ≤2mm, adopt a forced feeding process, set the feeding speed to 50-60kg / min, start the roller press to dry-press the powder slag into pillow-shaped slag balls, which are the refining slag-removing agent.

[0053] Next, the present application provides a smelting method of applying the aforementioned refining slag-removing agent to a low-carbon steel wire rod, which specifically comprises the following steps:

[0054] Step S1, after the electric furnace / converter smelting is completed, steel is tapped. When the tapping reaches 1 / 3 of the total amount, silicon-manganese alloy, ferrosilicon, carbon powder and active lime are added to the molten steel in sequence. After the tapping is completed, a refining slag-removing agent is added to the slag surface, and bottom blowing and stirring of the ladle behind the furnace are started at the same time;

[0055] Preferably, the amount of silicon manganese alloy added is 1.6-1.8kg / t, the amount of ferrosilicon added is 2-3kg / t, the amount of carbon powder added is 0-1.5kg / t, the amount of active lime added is 2-2.5kg / t, and the amount of refining slag agent added is 1.5-2kg / t; after the furnace is opened, the gas flow rate of ladle bottom blowing and stirring is 600-800NL / min, and the stirring time lasts 8-10min.

[0056] Step S2, the ladle enters the refining process, samples the molten steel and measures its temperature, then adds lime, starts refining bottom blowing and stirring, and then inserts electrodes to energize and heat.

[0057] Preferably, the amount of lime added is 1-3 kg / t; the gas flow rate for starting refining bottom blowing and stirring is 400-600 NL / min.

[0058] Step S3, after the heating is completed, stir in vain for 3-5 minutes, add the refining slag agent for the second time, and add silicon-manganese alloy, ferrosilicon and carbon powder according to the measured molten steel composition to adjust the molten steel composition to the target composition range, then add calcium carbide to the slag surface, and enter step S4 after soft stirring;

[0059] Preferably, the gas flow rate of air stirring bottom blowing is 600-800NL / min, the secondary addition amount of refining slag agent is 0.5-1kg / t, the addition amount of calcium carbide is 0.4-0.6kg / t, the gas flow rate of soft stirring is 150-200NL / min, and the soft stirring time lasts for 5-8min.

[0060] Step S4, enter the continuous casting process, use a small square billet continuous casting machine with a cross section of 150mm×150mm to cast molten steel, and protect the casting process throughout the process. In the fully protected casting process, set the molten steel superheat to 20-30℃, the continuous casting billet pulling speed to 2.5-3.5m / min, and the secondary cooling water volume to 1.1-1.5L / kg.

[0061] Regarding the smelting method described above, the two-step slag deoxidation and modification process proposed in step S1-step S3 is an important factor in realizing the metallurgical function of the refining slag-reducing agent. First, half of the refining slag-reducing agent is added after the steel is tapped to accelerate the melting of lime, and the slag under the steel is modified to increase the MgO content and reduce the oxidizability of the original slag, in preparation for the desulfurization of molten steel. Then, after the refining power-on stirring is completed, the refining slag-reducing agent is added for the second time to achieve rapid slag removal and desulfurization, and prevent the slag oxidation from being enhanced due to the process slag-metal reaction, the refractory erosion is aggravated, and the molten steel is resulfurized.

[0062] The use of waste magnesia carbon bricks can replace light-burned magnesia balls as the raw material for refining slag-forming agents to avoid the increase of slag viscosity, decrease of basicity, deterioration of desulfurization effect, and difficulty in quality control requirements. In addition to the MgO particles and residual carbon in the waste magnesia carbon bricks, the fine MgO grains can melt quickly after hot mixing and fully react with other components in the slag to form clinker with good metallurgical properties. The most important thing is that the residual carbon in the waste magnesia carbon bricks has a certain reducibility. The residual carbon is used for deoxidation and modification, and the deoxidation product is gaseous carbon oxide. Carbon deoxidation is a prerequisite for the application of secondary deoxidation and modification technology of silicon-killed steel slag.

[0063] Here we need to emphasize why carbon deoxidation is a prerequisite for the application of secondary deoxidation and modification technology for silicon-killed steel slag. As another innovative point of this application, the secondary deoxidation and modification technology for silicon-killed steel slag. The traditional secondary deoxidation and modification technology for refined slag is usually used for aluminum-killed steel smelting. Slag surface deoxidizers are added during the steelmaking process of the primary furnace and the LF refining process to achieve secondary deoxidation and modification of the slag, improve the desulfurization capacity of the refined slag, and reduce the total oxygen content of the molten steel. However, there are few studies on the secondary deoxidation and modification of the slag of silicon-killed steel. First, in order to prevent the deoxidation reaction from generating Al2O3 that enters the molten steel and causes the problem of excessive Class B inclusions, silicon-killed steel generally does not use traditional slag surface deoxidizers (the main component of which contains Al) to deoxidize and modify the slag. In particular, when the slag surface deoxidizer is added during the refining process for secondary deoxidation and modification, a large amount of Al2O3 is generated and enters the molten steel and cannot be removed, which has a great impact on the cleanliness of the finished steel. However, if a slag surface deoxidizer containing SiC is used to deoxidize and modify the slag, the deoxidation product SiO2 will continuously reduce the slag basicity, resulting in a decrease in the desulfurization capacity of the refined slag and an increase in its corrosiveness.

[0064] Therefore, after the residual carbon in the waste magnesia carbon bricks is deoxidized and modified, its deoxidation product is gaseous carbon oxides, which are volatilized during the smelting process and will not have an adverse effect on the slag and molten steel. At the same time, the refined slag is secondary deoxidized and modified by a reasonable feeding method to obtain a CaO-Al2O3-SiO2-MgO quaternary refined slag system with a high MgO content, which replaces the original CaO-SiO2 slag system, achieves the purpose of refining rapid slag and desulfurization, and reduces the speed of erosion of the ladle refractory. Compared with the existing refining slag-forming agent and its application in the smelting method of low-carbon steel wire, it can not only meet the requirements of low-cost and pollution-free products, but also achieve the metallurgical functions of refining rapid slag, desulfurization and reducing the erosion of the ladle refractory.

[0065] In order to comprehensively compare the technical advantages of the present application, three groups of embodiments and two groups of comparative examples are provided, and the technical and economic indicators of the embodiments are compared and verified with the integrated data of the comparative examples and the ladle life data.

[0066] Embodiment 1:

[0067] The molten killed steel refining waste slag produced at the end of pouring was measured to have an S content of 0.22%, an SiO2 content of 2.15%, and a waste slag temperature of 1427°C. The MgO content of the waste magnesia carbon brick particles with a particle size of 1-5 mm was measured to be 77%, the C content was 8.7%, the CaO content was 12.4%, and other inevitable impurity components.

[0068] Pour molten killed steel refining waste slag into the mixed slag pot, the amount of which is 630kg. Use a spray gun to evenly spray the waste magnesia carbon brick particles into the mixed slag pot, the amount of which is 70kg, and allow the two to fully mix and react, then cool naturally for 30 minutes.

[0069] Repeat the above operation 15 times, fill the mixed slag pot, let the filled mixed slag pot stand and cool for 24 hours, then pour out the mixed slag. The total amount of 12CaO•7Al2O3 and 3CaO•Al2O3 in the mixed slag is 71%, and the hemispherical point temperature is ≤1366℃.

[0070] After two-stage crushing and iron removal, the slag powder is produced; finally, the raw slag with qualified particle size is obtained through a screening device with an aperture of 3mm and loaded into the raw material bin. The mass proportion of the raw slag with a particle size of ≤3mm is 99%, and the mass proportion of the particle size of >6mm is 0.

[0071] The roller press equipped with forced feeding function is set with a minimum roller gap distance of 1mm, a roller pressing pressure of 2800MPa, and a feeding speed of 60kg / min. The collected raw slag is dry-pressed into 50mm pillow-shaped slag balls and bagged for later use.

[0072] The collected pillow-shaped slag balls are the refining slag-forming agent, and its main components are 57% CaO, 28% Al2O3, 14% MgO, 0.2% total FeO and MnO, 2.3% SiO2, 1.4% C, and 0.08% S. Then it is applied to the smelting of low-carbon steel wire. In an electric furnace steelmaking workshop with a nominal capacity of 100t, the low-carbon steel wire refining slag-forming method provided by the present application is adopted. In terms of weight percentage, the main components of the low-carbon steel wire are 0.2-0.25% C, 0.4-0.6% Si, 1.3-1.4% Mn, ≤0.015% P, ≤0.01% S, ≤0.005% Al, and Fe and other inevitable impurity components.

[0073] In the No. 1 ladle, the smelting process route is electric furnace smelting-ladle refining-continuous casting pouring, specifically: after the electric furnace smelting is completed, when the steel output reaches 1 / 3 of the total, 1785kg of silicon manganese alloy, 214kg of ferrosilicon, 110kg of carbon powder and 220kg of active lime are added to the molten steel in sequence; after the steel output is completed, 175kg of refining slag-removing agent is added, and the bottom blowing and stirring of the ladle behind the furnace is turned on, and the bottom blowing gas flow rate is 800NL / min.

[0074] After stirring for 8 minutes, the ladle enters the refining process. First, take samples to measure the temperature, add 155kg of lime, start refining bottom blowing and stirring, the bottom blowing gas flow rate is 600NL / min, and then insert electrodes to energize and heat.

[0075] After 5 minutes of power on and 3 minutes of continuous air stirring, the slag was well deslagging and the slag was light white. 78 kg of refining deslagging agent was added. According to the measured molten steel composition, 205 kg of silicon manganese alloy, 115 kg of ferrosilicon and 25 kg of carbon powder were added to adjust the molten steel composition to the target composition range. Finally, 40 kg of calcium carbide was added to the slag surface, and the continuous casting process was entered after soft stirring for 5 minutes. The bottom blowing gas flow rate of soft stirring was 150 NL / min.

[0076] The continuous casting adopts a small square billet continuous casting machine with a cross-section of 150mm×150mm to pour the molten steel. The pouring process is protected throughout the whole process. The superheat of the molten steel is 28℃, the continuous casting billet pulling speed is 3.3m / min, and the secondary cooling water volume is 1.3L / kg.

[0077] In this embodiment, a total of 253 kg of refining slag-removing agent is used from the steel tapping of the electric furnace to the end of refining; the refining slag-removing time is 8 minutes, calculated from the start of power-on to the complete melting of the refining slag; and the desulfurization rate of the molten steel during the refining process is 85%.

[0078] Embodiment 2:

[0079] The preparation method of the refining slag-removing agent is the same as that of Example 1.

[0080] Then, the collected refining slag-forming agent is applied to the smelting of low-carbon steel wire rod, and the low-carbon steel wire rod refining slag-forming method provided by the present application is adopted in an electric furnace steelmaking workshop with a nominal capacity of 100t. In terms of weight percentage, the main components of the low-carbon steel wire rod are 0.2-0.25% C, 0.4-0.6% Si, 1.3-1.4% Mn, ≤0.015% P, ≤0.01% S, ≤0.005% Al, and Fe and other inevitable impurity components.

[0081] In the No. 1 ladle, the smelting process route is electric furnace smelting-ladle refining-continuous casting pouring, specifically: after the electric furnace smelting is completed, when the steel output reaches 1 / 3 of the total, 1774kg of silicon manganese alloy, 254kg of ferrosilicon, 141kg of carbon powder and 217kg of active lime are added to the molten steel in sequence; after the steel output is completed, 187kg of refining slag-removing agent is added, and the bottom blowing and stirring of the ladle behind the furnace is turned on, and the bottom blowing gas flow rate is 800NL / min.

[0082] After stirring for 8 minutes, the ladle enters the refining process. First, take samples to measure the temperature, add 133kg of lime, start refining bottom blowing and stirring, the bottom blowing gas flow rate is 600NL / min, and then insert electrodes to energize and heat.

[0083] After energizing for 5 minutes and continuing to stir in the air for 3.5 minutes, the slag was well deslagging and the slag was light white. 88 kg of refining deslagging agent was added. According to the measured composition of the molten steel, 192 kg of silicon manganese alloy, 149 kg of ferrosilicon and 20 kg of carbon powder were added to adjust the composition of the molten steel to the target composition range. Finally, 40 kg of calcium carbide was added to the slag surface, and after soft stirring for 5 minutes, the continuous casting process was entered. The bottom blowing gas flow rate of soft stirring was 150 NL / min.

[0084] The continuous casting adopts a small square billet continuous casting machine with a cross-section of 150mm×150mm to pour the molten steel. The pouring process is protected throughout the whole process. The superheat of the molten steel is 29℃, the continuous casting billet pulling speed is 3.3m / min, and the secondary cooling water volume is 1.3L / kg.

[0085] In this embodiment, a total of 275 kg of refining slag-removing agent is used from the tapping of the electric furnace to the end of refining; the refining slag-removing time is 8.5 minutes, calculated from the start of power-on to the complete melting of the refining slag; and the desulfurization rate of the molten steel during the refining process is 88%.

[0086] Embodiment 3:

[0087] The preparation method of the refining slag-removing agent is the same as that of Example 1.

[0088] Then, the collected refining slag-forming agent is applied to the smelting of low-carbon steel wire rod, and the low-carbon steel wire rod refining slag-forming method provided by the present application is adopted in an electric furnace steelmaking workshop with a nominal capacity of 100t. In terms of weight percentage, the main components of the low-carbon steel wire rod are 0.2-0.25% C, 0.4-0.6% Si, 1.3-1.4% Mn, ≤0.015% P, ≤0.01% S, ≤0.005% Al, and Fe and other inevitable impurity components.

[0089] In the No. 1 ladle, the smelting process route is electric furnace smelting-ladle refining-continuous casting pouring, specifically: after the electric furnace smelting is completed, when the steel output reaches 1 / 3 of the total, 1787kg of silicon manganese alloy, 203kg of ferrosilicon, 133kg of carbon powder and 218kg of active lime are added to the molten steel in sequence; after the steel output is completed, 192kg of refining slag-removing agent is added, and the bottom blowing and stirring of the ladle behind the furnace is turned on, and the bottom blowing gas flow rate is 800NL / min.

[0090] After stirring for 8 minutes, the ladle enters the refining process. First, take samples to measure the temperature, add 167kg of lime, start refining bottom blowing and stirring, the bottom blowing gas flow rate is 600NL / min, and then insert electrodes to energize and heat.

[0091] After 5 minutes of power on and 3.3 minutes of air stirring, the slag was well deslagging and the slag was light white. 84 kg of refining deslagging agent was added. According to the measured molten steel composition, 212 kg of silicon manganese alloy, 108 kg of ferrosilicon and 20 kg of carbon powder were added to adjust the molten steel composition to the target composition range. Finally, 40 kg of calcium carbide was added to the slag surface, and the continuous casting process was entered after soft stirring for 5 minutes. The bottom blowing gas flow rate of soft stirring was 150 NL / min.

[0092] The continuous casting adopts a small square billet continuous casting machine with a cross-section of 150mm×150mm to pour the molten steel. The pouring process is protected throughout the whole process. The superheat of the molten steel is 27℃, the continuous casting billet pulling speed is 3.3m / min, and the secondary cooling water volume is 1.3L / kg.

[0093] In this embodiment, a total of 276 kg of refining slag-removing agent is used from the steel tapping of the electric furnace to the end of refining; the refining slag-removing time is 8.3 minutes, calculated from the start of power-on to the complete melting of the refining slag; the desulfurization rate of the molten steel during the refining process is 87%.

[0094] Comparative Example 1:

[0095] This comparative example adopts a conventional smelting method to apply fluorite to the smelting of low-carbon steel wire. In an electric furnace steelmaking workshop with a nominal capacity of 100t, a conventional low-carbon steel wire refining slag method is adopted. In terms of weight percentage, the main components of the low-carbon steel wire are C 0.2-0.25%, Si 0.4-0.6%, Mn 1.3-1.4%, P ≤ 0.015%, S ≤ 0.01%, Al ≤ 0.005%, and Fe and other inevitable impurity components.

[0096] In the No. 2 ladle, the smelting process route is electric furnace smelting-ladle refining-continuous casting pouring, specifically: after the electric furnace smelting is completed, when the steel output reaches 1 / 3 of the total, 1782kg of silicon manganese alloy, 221kg of ferrosilicon, 114kg of carbon powder and 225kg of active lime are added to the molten steel in sequence; and the bottom blowing and stirring of the ladle behind the furnace is turned on, and the bottom blowing gas flow rate is 800NL / min.

[0097] After stirring for 8 minutes, the ladle enters the refining process. First, take samples and measure the temperature, add 155kg of lime and 163kg of fluorite, start refining bottom blowing and stirring, the bottom blowing gas flow rate is 600NL / min, and then insert electrodes to energize and heat.

[0098] After energizing for 5 minutes and continuing to stir in the air for 4 minutes, the slag was well slag-forming and the slag was gray. According to the measured molten steel composition, 217kg of silicon-manganese alloy, 109kg of ferrosilicon and 20kg of carbon powder were added to adjust the molten steel composition to the target composition range, and 60kg of calcium carbide was added to the slag surface. After soft stirring for 5 minutes, the continuous casting process was entered, and the bottom blowing gas flow rate of soft stirring was 150NL / min.

[0099] The continuous casting adopts a small square billet continuous casting machine with a cross-section of 150mm×150mm to pour the molten steel. The pouring process is protected throughout the whole process. The superheat of the molten steel is 28℃, the continuous casting billet pulling speed is 3.3m / min, and the secondary cooling water volume is 1.3L / kg.

[0100] In this embodiment, a total of 163 kg of fluorite is used from the tapping of the electric furnace to the end of refining; the refining slag time is 9 minutes, calculated from the start of power-on to the complete melting of the refined slag; the desulfurization rate of the molten steel during the refining process is 78%.

[0101] Comparative Example 2:

[0102] This comparative example adopts a conventional smelting method, and applies the purchased pre-melted slag to the smelting of low-carbon steel wire rods. The main component of the pre-melted slag is calcium silicate, and the basicity is 1.0. In an electric furnace steelmaking workshop with a nominal capacity of 100t, a conventional low-carbon steel wire rod refining slag method is adopted. In terms of weight percentage, the main components of the low-carbon steel wire rod are C 0.2-0.25%, Si 0.4-0.6%, Mn 1.3-1.4%, P ≤0.015%, S ≤0.01%, Al ≤0.005%, and Fe and other inevitable impurity components.

[0103] In the 3# ladle, the smelting process route is electric furnace smelting-ladle refining-continuous casting, specifically: after the electric furnace smelting is completed, when the steel output reaches 1 / 3 of the total, 1792kg of silicon manganese alloy, 219kg of ferrosilicon, 118kg of carbon powder and 230kg of active lime are added to the molten steel in sequence; after the furnace is opened, the ladle is bottom blown and stirred, and the bottom blowing gas flow rate is 800NL / min.

[0104] After stirring for 8 minutes, the ladle enters the refining process. First, take samples and measure the temperature, add 221kg of lime and 581kg of calcium silicate pre-melted slag, start refining bottom blowing and stirring, the bottom blowing gas flow rate is 600NL / min, and then insert electrodes to energize and heat.

[0105] After energizing for 5 minutes and continuing to stir for 5 minutes, the slag was not good, there were a few lumps on the slag surface, and the slag was gray. After continuing to stir for 3 minutes, the slag was good. According to the measured molten steel composition, 211kg of silicon manganese alloy, 108kg of ferrosilicon and 30kg of carbon powder were added to adjust the molten steel composition to the target composition range, and 60kg of calcium carbide was added to the slag surface. After soft stirring for 5 minutes, the continuous casting process was entered. The bottom blowing gas flow rate of soft stirring was 150NL / min.

[0106] The continuous casting adopts a small square billet continuous casting machine with a cross-section of 150mm×150mm to pour the molten steel. The pouring process is protected throughout the whole process. The superheat of the molten steel is 28℃, the continuous casting billet pulling speed is 3.3m / min, and the secondary cooling water volume is 1.3L / kg.

[0107] In this comparative example, a total of 581 kg of pre-melted slag was used from the steel tapping of the electric furnace to the end of refining; the refining slag time was 13 minutes, calculated from the start of power-on to the complete melting of the refined slag; the desulfurization rate of the molten steel during the refining process was 70%, and the desulfurization effect was poor.

[0108] The technical and economic indicators of the above Examples 1-3 and Comparative Examples 1-2 are integrated to obtain Table 1.

[0109] Table 1 Integrated data of technical and economic indicators of examples and comparative examples

[0110]

[0111] In Examples 1-3, 1# ladle was used. After 133 furnaces were smelted continuously using the refining slag-forming agent slag-forming process, the 1# ladle was taken offline for replacement of the refractory materials of the ladle. In Comparative Example 1, 2# ladle was used. After 66 furnaces were smelted continuously using the fluorite slag-forming process, the 2# ladle was taken offline for replacement of the refractory materials of the ladle. In Comparative Example 2, 3# ladle was used. After 77 furnaces were smelted continuously using the pre-melted slag slag-forming process, the 3# ladle was taken offline for replacement of the refractory materials of the ladle. The ladle life data were integrated to obtain Table 2.

[0112] Table 2 Ladle life data of examples and comparative examples

[0113]

[0114] Through the comparison and verification of the embodiments and comparative examples in Tables 1 and 2 above, the refining slag-forming agent and its preparation method proposed in this application realize the secondary utilization of aluminum-killed steel refining waste slag and waste magnesium carbon bricks, and solve the problem of high production cost of fluorite and pre-melted slag. This application provides a smelting method for low-carbon steel wire rods using a refining slag-forming agent, which adopts the idea of ​​refining slag-forming agent to make a fluorine-free low-melting point CaO-Al2O3-SiO2-MgO slag system, which increases the proportion of low-melting point phase components in the refined slag without affecting the metallurgical function of the original slag system, and not only realizes metallurgical functions such as rapid refining slag-forming and desulfurization, but also reduces the erosion rate of the refractory material of the ladle.

[0115] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0116] The meaning of "and / or" described in this application means that the situations where each exists alone or both exist at the same time are included.

[0117] The term “connection” as used in this application may mean a direct connection between components or an indirect connection between components via other components.

[0118] 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 refining slag-removing agent, characterized in that: It includes aluminum killed steel refining waste slag and waste magnesium carbon bricks. According to the mass percentage, the mixing ratio of the two ranges from aluminum killed steel refining waste slag to waste magnesium carbon bricks = 8:2-9:1; Wherein, in the aluminum killed steel refining waste slag, S≤0.3% and SiO2<3% by mass percentage; The waste magnesia carbon bricks contain MgO≥60% by mass, C is 5-15%, and the rest is CaO and other inevitable impurities; The main components of the refining slag-forming agent include, by mass percentage, 50-55% CaO, 25-30% Al2O3, 10-15% MgO, the total amount of FeO and MnO ≤0.5%, SiO2 ≤3%, C 0.8-2%, S ≤0.1%; After mixing the aluminum killed steel refining waste slag and the waste magnesia carbon bricks, the total amount of 12CaO•7Al2O3 and 3CaO•Al2O3 in the mineral phase composition of the mixture is ≥65%, and the hemisphere point temperature is ≤1380℃.

2. The method for preparing the refining slag-removing agent according to claim 1, characterized in that: The specific steps include: The first step is to pour the molten aluminum killed steel refining waste slag into the mixing slag tank, and then spray the waste magnesium carbon brick particles. The particle size of the waste magnesium carbon brick particles is 1-5mm. The single mixing amount of aluminum killed steel refining waste slag and waste magnesium carbon bricks is ≤800kg. The temperature before mixing is set to ≥1200℃. After fully mixing, it is naturally cooled. The cooling time is set to 30-40 minutes. Step 2: Repeat the steps in step 1 until the slag tank is filled with mixed slag; In the third step, the mixed slag cooled to room temperature in the slag tank is poured out, and is crushed and iron-removed in two stages to form powder slag, which is then screened and the powder slag that meets the screening standards is loaded into the raw material bin; The fourth step is to start the roller press in the raw material bin to dry-press the powder slag into pillow-shaped slag balls, which are the refining slag-reducing agent.

3. The method for preparing the refining slag-removing agent according to claim 2, characterized in that: In the third step, the screening standard is that, by mass percentage, the proportion of powder residue with a particle size of ≤3 mm is greater than or equal to 90%, and the proportion of powder residue with a particle size of >6 mm is less than 3%; In the fourth step, the roller press pressure is set to 2500-3000MPa, the minimum gap between the extrusion rollers is ≤2mm, a forced feeding process is adopted, and the feeding speed is set to 50-60kg / min.

4. A method for smelting low-carbon steel wire using a refining slag-removing agent, characterized in that: The specific steps include: Step S1, after the electric furnace / converter smelting is completed, steel is tapped. When the tapped steel reaches 1 / 3 of the total amount, silicon-manganese alloy, ferrosilicon, carbon powder and active lime are added to the molten steel in sequence. After the tapping is completed, the refining slag-removing agent according to claim 2 is added to the slag surface, and the bottom blowing and stirring of the ladle behind the furnace are started at the same time; Step S2, the ladle enters the refining process, samples the molten steel and measures its temperature, then adds lime, starts refining bottom blowing and stirring, and then inserts electrodes to energize and heat. Step S3, after the heating is completed, stir for 3-5 minutes, add the refining slag-removing agent described in claim 2 for the second time, and add silicon-manganese alloy, ferrosilicon and carbon powder according to the measured molten steel composition to adjust the molten steel composition to the target composition range, then add calcium carbide to the slag surface, and enter step S4 after soft stirring; Step S4, entering the continuous casting process, using a small square billet continuous casting machine with a cross-section of 150mm×150mm to pour molten steel, and protecting the pouring process throughout the process.

5. The method for smelting low-carbon steel wire rods by applying a refining slag-removing agent to claim 4, characterized in that: In step S1, the amount of silicon manganese alloy added is 1.6-1.8 kg / t, the amount of ferrosilicon added is 2-3 kg / t, the amount of carbon powder added is 0-1.5 kg / t, the amount of active lime added is 2-2.5 kg / t, and the amount of refining slag-forming agent added is 1.5-2 kg / t; After the furnace is turned on, the gas flow rate of the ladle bottom blowing and stirring is 600-800NL / min, and the stirring time lasts 8-10min.

6. The method for smelting low-carbon steel wire rods using a refining slag-removing agent according to claim 4, characterized in that: In step S2, the amount of lime added is 1-3 kg / t; The gas flow rate for starting refining bottom blowing and stirring is 400-600NL / min.

7. The method for smelting low-carbon steel wire rods by using a refining slag-removing agent according to claim 4, characterized in that: In step S3, the gas flow rate of air stirring bottom blowing is 600-800NL / min, the secondary addition amount of refining slag agent is 0.5-1kg / t, the addition amount of calcium carbide is 0.4-0.6kg / t, the gas flow rate of soft stirring is 150-200NL / min, and the soft stirring time lasts for 5-8min.

8. The method for smelting low-carbon steel wire rods using a refining slag-removing agent according to claim 4, characterized in that: In step S4, during the whole protection casting process, the superheat of molten steel is set to 20-30°C, the continuous casting billet drawing speed is set to 2.5-3.5m / min, and the secondary cooling water volume is set to 1.1-1.5L / kg.

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