Molten scrap iron composition regulator, preparation method and application

Abstract

The application discloses a molten scrap iron liquid component regulator, which comprises 5-15% of low-cost silicon-aluminum-calcium-carbon alloy, 50-60% of crystalline silicon cutting tertiary sand, 10-20% of carbonaceous material, 2-5% of organic fiber, 15-25% of passivated lime and 1-3% of binding agent in percentage by weight; and a preparation method and application thereof are provided. Through the introduction of the low-cost silicon-aluminum-calcium-carbon alloy, the alloying element dissolution supplement in the liquid iron is realized, the chemical heat of the liquid iron into the furnace is improved, the enrichment of harmful elements and difficult-to-remove residual elements is reduced, the deep desulfurization of the Ca alloy element in the liquid iron is realized, the stability of sulfides in the desulfurization slag is improved, and the resulfurization in the converter is inhibited; through the molten scrap iron liquid component regulator and the application method, the online component regulation after the desulfurization and slagging of the molten scrap iron liquid is realized, and through the full-amount addition of the liquid surface regulator of the liquid iron in the liquid iron tank, the heat supplement and temperature rise of the regulator in the converter are realized.

Description

Technical Field

[0001] This invention belongs to the field of ferroalloy technology, specifically relating to a molten waste steel composition regulator, its preparation method, and its application. Background Technology

[0002] With the rapid development of my country's steel industry, iron ore consumption has risen sharply. For integrated steel enterprises, reducing the hot metal ratio and increasing the scrap steel ratio in converters has become an urgent need for low-carbon and green development. The amount of scrap steel added to a single converter process is limited by the volume of the scrap steel trough and constrained by the converter's heat balance and production rhythm, hindering the effective improvement of the scrap steel ratio in converter smelting. Therefore, the technology of adding scrap steel to hot metal has emerged and become an important way for steel enterprises to improve the scrap steel ratio and production efficiency in converter steelmaking. By adding scrap steel to the hot metal ladle and torpedo ladle after the blast furnace is poured, and utilizing the residual heat of the empty ladle or a scrap steel baking device to preheat the scrap steel, the scrap steel is melted in the hot metal through heating and carburizing of the hot metal after it has received iron in the blast furnace, thus reducing heat loss due to iron transfer. However, the large temperature drop and low temperature of molten iron during the transfer of hot iron result in a slow carburizing and melting rate of scrap steel, which restricts the quantity and size of scrap steel in the hot iron process. Although preheating of scrap steel increases the temperature of scrap steel when receiving iron and shortens the heating and carburizing melting time of molten iron, incomplete melting of slightly larger scrap steel often occurs in actual production, which seriously affects the normal production of hot iron desulfurization pretreatment. Therefore, the control of the amount of small-sized scrap steel crushed and added has become the main way to add scrap steel to hot iron. However, in actual production, it has been found that after adding scrap steel to an empty ladle or torpedo ladle, the top slag of the molten iron becomes viscous, has low basicity, high iron oxide content, increases the temperature drop of the molten iron, and decreases the carbon and silicon content of the molten iron. This not only makes it difficult to desulfurize and remove slag from the molten scrap steel, seriously affecting the sulfur content and slag amount of the molten iron entering the furnace, the amount of sulfur recovery in the converter, the implementation of the production plan for special steel smelting, and the overall production organization, but also makes the temperature of the molten iron entering the furnace low and the carbon and silicon content uncontrollable. This results in poor adaptability of the converter static model, affecting the precise execution of the temperature regime, oxygen blowing regime, slag formation regime, and batching regime in the smelting process, as well as the temperature control of the carbon-oxygen product in the tapped steel. Therefore, how to overcome the series of problems caused by adding scrap steel to molten iron has become one of the key technologies that urgently need to be broken through in the current converter smelting of large scrap steel ratios.

[0003] To address the challenges of desulfurization and slag removal, reduced chemical and physical heat in the converter, and significant changes in the converter smelting process caused by adding scrap steel to torpedo ladles or molten iron ladles, sampling analysis and theoretical research during the blast furnace operation process of adding crushed scrap steel to empty molten iron ladles or torpedo ladles revealed that the small size, large surface area, severe surface oxidation, and high amount of entrained dirt and debris in the crushed scrap steel resulted in a large amount of iron oxide and dirt and debris introduced into the empty ladle. This issue can be further addressed by considering the iron oxide content and dirt and debris entrainment in the crushed scrap steel. Based on calculations of 3% scrap steel added to molten iron, 3% scrap steel added by weight, and 0.6% slag added during blast furnace tapping, the amounts of iron oxide, soil, and debris introduced from scrap steel per ton of molten iron are 0.9 kg, 0.9 kg, and 6 kg, respectively. This means that the total slag volume increases by 1.8 kg per ton of molten iron due to the addition of scrap steel, and the iron oxide content in the slag increases by more than 11%. Furthermore, during the blast furnace tapping process after adding scrap steel to an empty ladle, the scrap steel is subjected to scouring and agitation by the molten iron. When FeO reacts with molten iron at the interface, it oxidizes the Si in the molten iron to generate a large amount of SiO2, thereby reducing the basicity of the molten iron slag. If all of the additional 0.9 kg of FeO per ton reacts with the Si in the molten iron, the amount of silicon alloy in the molten iron will decrease by 0.175 kg, the silicon content in the molten iron will decrease by 0.0175%, and 0.4 kg of SiO2 will be generated, increasing the SiO2 content in the molten iron slag by 5.48%. At the same time, conventional soil inclusions are mainly characterized by increased silica content. Acidic impurities further reduce the basicity of the molten iron slag after adding scrap steel, forming highly oxidizing, viscous, acidic molten iron slag. At the same time, as the scrap steel in the molten iron is heated and its temperature rises, the temperature of the molten iron decreases, the saturated carbon content of the molten iron decreases, flake graphite precipitates, and the carbon content of the molten iron decreases further. As the scrap steel in the molten iron is carburized and melted, the carbon content of the molten iron decreases further. Driven by the carbon concentration difference of carburizing and melting, the carbon in the molten scrap steel is unsaturated, and the average carbon content of the molten iron continues to decrease. Ultimately, this results in a low carbon content in the molten scrap steel.Torpedo ladles or molten iron ladles are generally made of Al2O3-SiC-C refractory bricks. After adding scrap steel to the torpedo ladle or molten iron ladle, the FeO brought in by the scrap steel increases the FeO content in the molten iron slag, exacerbating the erosion and oxidation damage of the Al2O3-SiC-C refractory bricks. Specifically, SiC reacts with FeO, generating SiO2 which is trapped in the slag, reducing the W(CaO) / W(SiO2) ratio in the molten iron slag. Simultaneously, C reacts with FeO, producing CO and CO2 gases which are released, disrupting the C / C bonds in the Al2O3-SiC-C refractory bricks and causing a porous refractory brick structure. Loose aggregates detach from the slag, causing corundum or high-alumina aggregates to leach into the slag, thus reducing the W(CaO) / W(Al2O3) ratio in the molten iron slag. Therefore, adding scrap steel to torpedo ladles or molten iron ladles not only accelerates the damage process of Al2O3-SiC-C refractory bricks, but also reduces the carbon and silicon content of the molten iron, as well as the basicity, melting point, and oxidizing properties of the molten iron slag, and increases the temperature drop of the molten iron. This leads to difficulties in desulfurizing and removing slag from molten scrap steel, reduced chemical and physical heat of the molten iron entering the furnace, difficulties in slag formation in the converter, limited scrap steel ratio in the converter, long smelting cycles, high frequency of converter reblowing, and high oxygen content in the tapped steel.

[0004] Regarding the difficulty in desulfurization and slag removal caused by adding scrap steel to torpedo ladles and molten iron ladles, the literature "Liu Zikang, Zheng Yi, The Influence of Adding Scrap Steel to Torpedo Ladles on Molten Iron Slag and Desulfurization, Steelmaking, 2021, No.5" analyzes extensive field sampling. Under the condition of adding 38.5 kg / t of scrap steel to the torpedo ladle, the temperature drop of molten iron increases by 10°C. The temperature drop of molten iron has a relatively small impact on the desulfurization of molten scrap steel. It points out that reducing the amount of iron oxide entering the torpedo ladle is an important means to reduce SiO2 production and prevent the formation of oxidizing viscous slag. The following improvement measures are proposed: First, adjust the type of scrap steel from adding crushed material or silicon steel sheets to adding only silicon steel sheets; second, reduce the amount of scrap steel added from 10 t / ladle to 4 t / ladle; third, strengthen scrap steel management, standardize appearance quality requirements, eliminate scrap steel watering, and follow the last-in-first-out principle when feeding scrap steel into the torpedo ladle to avoid rusting. Through the above three aspects of work, the incidence of oxidizing viscous slag decreased from 40% to 15.6%. In addition, regarding the desulfurization difficulties caused by adding scrap steel to the torpedo ladle, on-site sampling and analysis revealed the main reasons for the low basicity, high oxidizing power, and viscosity of the molten iron slag after adding scrap steel to the torpedo ladle. This resulted in a large amount of metallic magnesium reacting with SiO2 in the slag during the magnesium-based injection desulfurization process of molten scrap steel, low saturated solubility of desulfurization products, and sulfur reversion, which inhibited the desulfurization reaction. To address this, improved measures were developed to remove viscous slag from molten iron before desulfurization. By employing a double slag removal method of "front slag removal + rear slag removal" for viscous slag furnaces, the sulfur content at the injection endpoint reached the expected target sulfur content requirement, and the utilization rate of metallic magnesium powder increased to 43.8%, which is 2.8% higher than that of single rear slag removal, but still 1.2% lower than that before adding scrap steel to the torpedo ladle. Although the double slag removal solved the desulfurization anomaly caused by adding scrap steel to the torpedo ladle, it also had an adverse impact on production and costs, increasing the desulfurization cycle by 6 minutes and increasing the iron loss from slag removal by 6.5 kg / t.

[0005] Regarding the issue of shortened service life caused by adding scrap steel to molten iron ladles, the literature "Xu Guotao, Zhao Yuan, Wu Jie, et al. Discussion on abnormal erosion and material issues of molten iron ladles under the condition of adding scrap steel, Refractory Materials, 2022, No.1" conducted on-site sampling analysis on the abnormal erosion of the refractory lining after adding scrap steel to molten iron ladles, and found that the main causes of damage were related to the quality and selection of the refractory lining. The analysis results showed that: (1) For the bottom of the ladle made of aluminosilicate carbon bricks (bulk density of 2.86 g / cm³), the erosion of the refractory lining was significantly reduced. 3 ) and aluminum silicon carbide carbon bricks for wall cladding (bulk density of 2.54 g / cm³) 3(2) Because the working lining bricks of the ladle wall have low density and high pyrophyllite content, although the cost can be greatly reduced, the main component of the ladle is SiO2. Under the erosion of the slag phase mainly composed of MnO and FeO, it is easy to cause the FeO and the ladle lining to undergo redox reaction, forming a porous and loose structure, and the compressive strength after firing is low. At the same time, after the steel plant implements the general contracting of refractory materials, due to the influence of the contract price, the refractory material suppliers often passively adopt substitute raw materials, resulting in the bulk density, apparent porosity and compressive strength of the refractory materials at the bottom and wall of the ladle being lower than the requirements of the industry standard. Therefore, the failure of the working lining bricks of the ladle to meet the process conditions of adding scrap steel to the ladle is the main reason for the damage. (3) Since the height of the scrap steel is about two-thirds of the ladle height, the molten iron does not necessarily enter the ladle directly to the bottom of the ladle. After entering through the gaps, it forms a swirling impact on the ladle lining. The swirling impact wear of molten iron containing unmelted steel particles on the furnace lining is large. However, the high-temperature strength of aluminum silicon carbide carbon bricks is not high, carbon is easily oxidized, silicon carbide content is low, and erosion resistance is poor. Impact causes brick breakage and brick falling off. For the addition of scrap steel to the molten iron ladle, some manufacturers use preheating to 800℃ or even gas oxygen gun heating. For example, the oxidation mass loss rate of aluminum silicon carbide carbon bricks used in the molten iron ladle wall at 1000℃ is 6.74%. During use, the wall bricks are oxidized to form a porous layer. Molten iron permeates through the porous layer, where carbon is precipitated and enriched. The oxidation reaction causes the brick lining to be loose and the strength to be reduced. The slag on the ladle wall has a low melting point, and its material needs to consider its high-temperature performance under the condition of adding scrap steel. In this case, the structure of the lining needs to be changed, such as casting a layer of carbon-free castable inside to improve the lining's resistance to erosion and wear. (3) The molten iron ladle insulation layer uses red silicate insulation bricks, which have high density and high strength, but poor insulation performance, resulting in a large temperature drop in the molten iron ladle. If the scrap steel is not baked and heated, it will not melt completely, which can easily cause steel and slag to stick to the ladle mouth and bottom, and aggravate the erosion of the molten iron ladle. Therefore, the refractory materials used for molten iron ladle lining must be improved in combination with changes in process conditions to increase their added value, rather than relying entirely on raw material substitution to reduce costs. For example, clay bricks or lightweight mullite bricks, although more expensive than red silica insulating bricks, have low density and good insulation performance.

[0006] To address the difficulties in desulfurizing and slag removal from molten scrap steel and the large fluctuations in the quality of molten iron entering the furnace, Chinese patent "Ouyang Degang, Sun Wei, Zhu Wanjun et al., Molten Scrap Steel Modifier and its Preparation Method and Application, Patent Application No.: 202210313316.0" discloses a molten scrap steel modifier and its preparation method and application. The modifier comprises the following raw materials in weight percentage: 55-75% low-cost silicon-aluminum-calcium-carbon alloy, 10-20% sintered calcium aluminate, 5-15% industrial soda ash, and 5-15% fluorite. The low-cost silicon-aluminum-calcium-carbon alloy is mainly composed of Si, Al, Ca, C alloying elements and metallic Fe, with P and S as the main impurity elements. The weight percentage content of Si, Al, Ca, and C alloying elements ranges as follows: Si: 35-45%, Al: 5-10%, Ca: 9-19%, C: 4-12%; the weight percentage content of metallic Fe ranges as follows: 1.5-2.5%; the weight percentage content of impurity elements P and S ranges as follows: P≤0.05%, S≤0.1%; the main component of the sintered calcium aluminate, 12CaO·7Al2O3, has a content ≥85%, and the main component of the fluorite, CaF2, has a content ≥85%. By introducing low-cost silicon-aluminum-calcium-carbon alloys and their high content of Si, Al, Ca, and C alloying elements into the molten steel modifier, not only are alloying elements in the molten iron replenished and deep deoxidation achieved, but the reduction and modification of the top slag in the molten iron is also completed, improving the thermodynamic conditions of the desulfurization reaction. In addition, efficient desulfurization of molten iron with Ca alloying elements is achieved, and MgS in the desulfurization slag is converted into CaS, improving the stability of sulfides in the desulfurization slag. By introducing sintered calcium aluminate with 12CaO·7Al2O3 as the main component and industrial-grade soda ash, the sulfur capacity and sulfur distribution coefficient of the desulfurization slag are improved, and the sulfur reversion of the desulfurization residue is suppressed. By adding industrial-grade soda ash and fluorite, the melting point of the desulfurization slag is lowered, the slag-metal interface reaction is promoted, the desulfurization efficiency is improved, and the sulfur reversion of the residue is suppressed. In industrial trials, online modification of molten scrap steel was achieved, yielding the expected results of reasonable control of alloy composition in molten scrap steel, efficient and stable deep desulfurization of molten iron, and smooth execution of slag removal. This achieved the comprehensive goals of stabilizing the quality of molten iron entering the furnace and reducing sulfur reversion at tapping. However, the molten scrap steel modifier was added before slag removal and before desulfurization. During desulfurization, the melting and deoxidation reaction of the low-cost silicon-aluminum-calcium-carbon alloy in the modifier improved the reducing thermodynamic conditions of molten scrap steel desulfurization, achieving the purpose of reducing modification of top slag and molten iron. However, due to factors such as insufficient modifier addition, secondary oxidation of alloy elements by air at the liquid surface, insufficient dissolution of molten iron within the limited desulfurization time, and losses from slag removal after desulfurization, the amount of alloy dissolved in the molten iron was low, resulting in insufficient chemical and thermal compensation for the molten iron entering the furnace after desulfurization, thus limiting the improvement of the converter scrap ratio.

[0007] Regarding the limitations imposed by adding scrap steel to the molten iron ladle on the scrap ratio in converter smelting, such as the molten iron temperature, carbon and silicon content, etc., the literature "Liu Lin, Zhang Derong, Ren Tao, et al., Practice of Improving the Scrap Ratio in Converters Using Heated Scrap Steel, Shanxi Metallurgy, 2022, No.6" states that, for example, when 50 kg / t of scrap steel is added to the molten iron, the molten iron temperature ranges from 213 to 1337℃, the carbon content ranges from 3.61 to 14.97%, the silicon content ranges from 0.09 to 10.68%, the manganese content ranges from 0.22 to 10.66%, the phosphorus content ranges from 0.080 to 10.160%, and the sulfur content ranges from 0.007 to 10.099%. This indicates that the added heat of the molten iron will result in insufficient heat for the 250 kg / t scrap steel ratio converter smelting, leading to severe converter over-oxidation, increased furnace lining erosion, and deterioration of the converter's economic and technical indicators. Therefore, improvements were proposed to increase the scrap ratio in the converter from using exothermic scrap. However, the addition of exothermic scrap altered the temperature rise during the converter process. In the later stages of blowing, the exothermic scrap melted, introducing large amounts of Si, Mn, and P elements, leading to re-drying in the later stages and hindering P removal. To increase the scrap ratio in the converter and achieve the goals of iron saving, steel production increase, and controlled P composition in converter smelting, the impact of adding exothermic scrap on converter operation, later re-drying, and phosphorus return in molten steel were tracked and recorded on-site. Furthermore, process optimization studies were conducted on the amount of exothermic scrap added, the converter blowing lance position, and the timing of charging under different hot metal conditions. The converter uses mainly mechanical pig iron as the exothermic scrap. This scrap is high in C, Si, and Mn, with average weight percentages of the following components: w(TFe) 91.23%, w(C) 5.12%, w(Si) 2.06%, w(Mn) 0.78%, w(P) 0.10%, and W(S) 0.10%. Research indicates that the mechanical pig iron has uneven block size, mostly falling into the category of heavy scrap. It cannot melt quickly in the early stages of blowing, but melts in the middle stages. As the molten pool temperature gradually increases, the mechanical pig iron melts rapidly, releasing large amounts of C, Si, and Mn. At this point, the sudden increase in Si and Mn in the molten steel leads to rapid oxidation and reaction with FeO in the slag, causing excessive FeO consumption and resulting in a re-drying phenomenon. By adjusting the scrap ratio and controlling the mechanical pig iron addition to 20%, the converter's heat output significantly improved. Based on the comparative analysis of the scrap steel ratio data before and after the addition of mechanically produced pig iron, the temperature drop of mechanically produced pig iron was 3.7℃ / t, which is 1.3℃ / t lower than that of normal scrap steel. The scrap steel consumption per unit increased by 7kg / t, and the final oxygen mass fraction decreased by 68×10⁻⁶. -6 By optimizing the lance position and controlling the amount of exothermic scrap added, process temperature, and slag addition, the problem of high phosphorus levels after the addition of exothermic scrap can be effectively solved, ensuring product quality. However, mechanically produced pig iron is large in size, has a slow melting rate, and contains high levels of harmful elements, which is detrimental to ensuring the quality of molten steel produced in converter smelting and restricts its large-scale application.

[0008] To address the problem of insufficient smelting heat in converters with a high scrap steel ratio and the low heat replenishment efficiency of conventional composite exothermic agents made of metallic silicon, metallic aluminum, and carbon, Chinese patent "Ouyang Degang, Sun Wei, Zhou Fu, et al., Composite Exothermic Agent for Converters and Preparation Method, Authorization Announcement No.: CN113005260B" discloses a composite exothermic agent for converters comprising a heat replenishing agent, a regulator, a catalyst, a weighting agent, a heat enhancing agent, and a binder. The mass percentages of each component are: heat replenishing agent 50-60%, regulator 10-15%, catalyst 1-3%, weighting agent 10-20%, heat enhancing agent 5-10%, and binder 2-4%. The heat-replenishing agent is composed of at least two of the following: waste graphite electrode powder, biochar powder, and semi-coke powder, with a particle size ≤0.150mm. The regulator is composed of quicklime powder and lightly calcined dolomite powder in a mass ratio of 2:1, with a particle size ≤0.150mm for both quicklime powder and lightly calcined dolomite powder. The catalyst is composed of pyrolusite powder with a particle size ≤0.150mm. The weighting agent is steel particles obtained by magnetic separation from the primary dust collector ash of a steelmaking converter, with a particle size ≤5mm and a TFe mass percentage content ≥85%. The heat-replenishing agent is composed of crystalline silicon cutting grade III sand with a particle size ≤0.150mm and secondary aluminum ash with a particle size ≤1mm, with a mass ratio of crystalline silicon cutting grade III sand to secondary aluminum ash of 4:1 to 9:1. The binder is composed of one or two of the following: phenolic resin and coal tar. This invention employs a heat-replenishing agent composed of at least two of the following: waste graphite electrode powder (particle size ≤0.150mm), biochar powder, and semi-coke powder. Leveraging the high fixed carbon content, low phosphorus and sulfur content, and excellent combustion characteristics of semi-coke and biochar powder, it improves combustion speed and temperature, reduces the introduction of harmful elements, and enhances the quality of molten steel produced in the converter. Furthermore, the compounding with waste graphite electrode powder increases the fixed carbon content and calorific value of the heat-replenishing agent, thereby increasing the heat output and reducing the introduction of harmful elements. The synergistic effect of biochar powder or semi-coke powder combustion overcomes the shortcomings of conventional graphite carbon balls, such as slow combustion speed, long burnout time, and low heat-replenishing efficiency. By pressing the converter composite heating agent into balls and adding a weighting agent, the strength and bulk density of the pressed balls are improved, preventing high-speed airflow from the converter from escaping and increasing the effective utilization rate of the heating agent. The addition of the heat-replenishing agent enhances the adaptability of the heating agent to low-Si iron converter smelting and promotes slag formation in the converter. By adding a regulator composed of active lime powder with a particle size ≤0.150mm and lightly calcined dolomite powder in a mass ratio of 2:1, the basicity of the ash from the converter composite exothermic agent combustion and the slagging rate are improved, avoiding the difficulties in converter slagging control caused by fluctuations in ash content and stabilizing converter smelting operations. Through the catalyst addition of pyrolusite powder with a particle size ≤0.150mm and the catalytic effect of MnO2 on carbon combustion, the combustion performance of fixed carbon in the reheating agent is further improved, increasing combustion efficiency and reheating effect, and promoting converter slagging.Steel particles with a particle size of ≤5mm obtained by magnetic separation from the dust collected during the primary dust removal process in steelmaking are used as weighting agents to increase the bulk density of the composite heating agent in the converter. This ensures sufficient contact between the agent and the molten steel during the combustion and reheating process in the furnace, reduces the thermal resistance of heat transfer, expands the heat transfer area, and improves the heat transfer efficiency. At the same time, the catalytic effect of iron oxides formed on the surface of the steel particles on the combustion of fixed carbon further improves the combustion characteristics of the heating agent, increases the reheating efficiency of the converter, and shortens the slag formation time in the converter. By adding a heat-enhancing agent composed of tertiary silicon cutting sand with a particle size ≤0.150mm and secondary aluminum ash with a particle size ≤1mm, the manufacturing cost of the converter composite exothermic agent is reduced, the utilization rate of waste resources is improved, and solid waste pollution is prevented. On the other hand, the high-calorific-value metallic silicon and silicon carbide in the tertiary silicon cutting sand and the high-calorific-value metallic aluminum in the secondary aluminum ash are fully utilized to increase the chemical heat and supplementary heat of the converter composite exothermic agent. Furthermore, the fluorides in the secondary aluminum ash promote the melting and slag formation rate of the converter slag, shortening the converter smelting time. Optimizing the proportion of the heat-enhancing agent avoids the adverse effects of excessively acidic oxide products from the silicon-based exothermic agent on the slag basicity. Simultaneously, it avoids the adverse effects of aluminum-based... Despite the high cost of heating agents, this method maintains the efficient heat replenishment function of silicon and aluminum heating agents. By introducing a small amount of aluminum heating agent components, it promotes slag formation in the converter smelting process and shortens the smelting cycle. By using one or two of phenolic resin and coal tar as binders, it ensures the bonding strength of the converter composite heating agent pressing balls, avoiding breakage, dust pollution, and escape from the converter fan during preparation, transportation, and converter addition. At the same time, it utilizes the combustion heating components of phenolic resin and coal tar to further improve the calorific value of the converter composite heating agent, and avoids the series of shortcomings of conventional water-soluble binders, such as moisture introduction and the resulting decrease in heat replenishment, damage to the magnesia-carbon brick lining, and vaporization heat absorption.

[0009] To address the issues of low acidity and high harmful element content in conventional exothermic agents primarily composed of carbonaceous components such as coking coal and anthracite, as well as the large slag volume of high-calorific-value metallic silicon, aluminum, and silicon carbide, Chinese patent "Ouyang Degang, Shen Jisheng, Sun Wei, et al., Composite Slag-Forming and Heat-Replenishing Agent for Converter Smelting with High Scrap Steel Ratio and its Preparation and Application Method, Patent Application No.: 202210306139.3" discloses a composite slag-forming and heat-replenishing agent for converter smelting with high scrap steel ratio, prepared from the following raw materials by weight percentage: 55-60% silicon-aluminum-calcium-carbon alloy, 10-15% sintered calcium aluminate, 5-10% wood charcoal, 5-10% sintered return ore, 10-15% manganese ore, 5-10% lightly calcined dolomite, and 0.3-0.5% sodium stearate. The high-calorific-value Si, Al, and Ca alloying elements in the silicon-aluminum-calcium-carbon alloy form corresponding alloying element oxides during the converter reheating process. This avoids the formation of high-temperature flue gas and external heat loss, improving the heat transfer rate and converter reheating efficiency during the reheating process. Simultaneously, the various highly reactive oxides formed by the oxygen-blown combustion of multiple alloying elements not only increase the material composition of the converter slag-forming materials and the formation conditions of low-melting-point composite oxides, but also promote the formation rate of composite oxides and the slag-forming rate in the converter through the high-activity oxidation products. Furthermore, the appropriate amount of C alloying element in the silicon-aluminum-calcium-carbon alloy, combined with the addition of charcoal, slows down the oxidation and combustion rate of the silicon-aluminum-calcium-carbon alloy in the converter and the reheating aging time, improving the converter smelting temperature regime and increasing dephosphorization efficiency. The combined addition of sintered calcium aluminate with low-melting-point 12CaO·7Al2O3 as the main component and lightly calcined dolomite not only increased the slag-forming rate in the converter but also improved the basicity of the slag, promoting the slag-metal reaction in converter smelting. Simultaneously, it increased the slag basicity and MgO content, reducing flux consumption and furnace lining erosion rates. The addition of sintered return ore and manganese ore lowered the converter slag-forming melting point, shortened the slag-forming time, improved the thermodynamic and kinetic conditions for converter dephosphorization, and increased dephosphorization efficiency. Furthermore, the catalytic effect of iron oxide and manganese oxide in the sintered return ore and manganese ore on the combustion of carbon materials increased the combustion rate and efficiency of carbon materials in the reheating agent, enhancing the reheating effect of the reheating agent. The introduction of sodium stearate improves the water resistance of the composite slag-forming heat-generating agent in converter smelting with a high scrap ratio, preventing moisture absorption during storage and transportation. At the same time, the medium-temperature decomposition and stirring of sodium stearate improve the thermodynamic and kinetic behavior of slag formation in the converter, thereby increasing the slag formation rate.

[0010] To address the shortcomings of high-calorific-value reheating agents such as ferrosilicon and silicon carbide, including high cost, large slag volume, and high converter lime consumption, Chinese patent "Ouyang Degang, Li Lingjun, Tong Gang, et al., A low-cost silicon-aluminum-calcium-carbon alloy and its preparation method, and its application in converter metallurgical reheating, patent application number: 202210440479.5" discloses a low-cost silicon-aluminum-calcium-carbon alloy for converter reheating, with the following chemical composition by weight percentage: Si: 35-45%, Al: 5-10%, Ca: 9-19%, C: 4-12%, Fe: 1.5-2.5%, P≤0.05%, S≤0.1%, and its unavoidable impurities. By alloying high-calorific-value Si, Al, and Ca alloying elements, corresponding alloying element oxides are formed during converter reheating, avoiding the formation of high-temperature flue gas and external heat loss, improving the heat transfer rate and converter reheating efficiency during the reheating process of the exothermic agent, and reducing the amount of exothermic agent added and the cost of converter reheating. In addition, the various highly active oxides formed by the oxygen-blown combustion of multiple alloying elements not only increase the material composition of converter slag-forming materials and the formation conditions of low-melting-point composite oxides, but also promote the formation rate of composite oxides and the slag-forming rate of converters by the highly active oxidation products. By appropriately incorporating C alloying elements into low-cost silicon-aluminum-calcium-carbon alloys, the oxidation combustion rate and reheating time of low-cost silicon-aluminum-calcium-carbon alloys in converters are slowed down, the converter smelting temperature regime is improved, and the dephosphorization efficiency is increased. Through the coupling optimization of the oxidation combustion characteristics of different alloying elements, the overall converter reheating effect of the low-cost silicon-aluminum-calcium-carbon alloy of this invention is improved, achieving the comprehensive objectives of reducing reheating agent and flux consumption, increasing the converter scrap ratio and metal yield, and shortening the smelting cycle.

[0011] In summary, for converter smelting processes with high scrap ratios under conditions of empty ladles or torpedo ladles with added scrap, the oxidation and inclusion of impurities on the surface of the crushed scrap lead to high oxidizability, low basicity, and viscous top slag in the molten iron slag after adding scrap. This results in the oxidation loss of easily oxidized alloying elements in the molten iron and an increased temperature drop during molten iron transfer. Although the invention of a low-cost silicon-aluminum-calcium-carbon alloy-based modifier for molten iron has improved the thermodynamics of molten iron desulfurization and slag removal, and increased the efficiency of molten iron desulfurization and slag removal, as well as the technical and economic indicators of pretreatment, the addition of the modifier during the molten iron desulfurization process results in low dissolution of reducing alloying components in the molten iron and high oxidation loss. Furthermore, the alloying components entering the desulfurization slag will also be removed during the slag removal process, leading to low effective utilization of the modifier's alloying components and a limited effect on improving the chemical heat of the molten iron entering the furnace. The limitations of existing technologies restrict the improvement of the scrap ratio in converter smelting and the stable control of molten steel quality. Furthermore, although low-cost silicon-aluminum-calcium-carbon alloys have low purity requirements and are inexpensive, their price is still high compared to industrial secondary solid waste containing alloying elements, hindering the full realization of economic benefits. To address the problem of insufficient heat in converter smelting with a high scrap ratio in molten scrap steel, the use of converter heat-generating agents and exothermic scrap has improved the converter's chemical thermal effect. However, the time required for adding heat-generating agents and exothermic scrap, as well as the time spent on in-furnace heating, melting, and oxidation reactions, prolongs the converter smelting cycle, leading to reduced converter production efficiency. Simultaneously, the difficulty in removing large amounts of residual and harmful elements introduced by conventional carbonaceous heat-generating agents and exothermic scrap restricts the composition hit rate of high-quality steel. High-purity alloy heat-generating agents are expensive, resulting in poor economic efficiency for converter heat-generating, even leading to negative returns. Further systematic research is needed to effectively overcome the shortcomings of existing technologies and achieve efficient, high-quality, and low-cost smelting of converters with a high scrap ratio under the condition of adding scrap steel to molten iron. Summary of the Invention

[0012] The purpose of this invention is to address the shortcomings of the aforementioned technologies by providing a molten scrap steel composition regulator, its preparation method, and its application. This molten scrap steel composition regulator has the advantages of low harmful element content, low cost, and simple preparation. Furthermore, its addition to the molten iron ladle after desulfurization and slag removal offers advantages such as ease of use, high alloy yield, precise control of alloy content in the molten scrap steel, and chemical and thermal stability of the molten iron entering the furnace. This improves converter thermal efficiency, promotes slag formation, shortens the converter smelting cycle, inhibits the enrichment of residual and harmful elements in the molten steel, and reduces the oxygen content at the tapping point. Ultimately, it achieves the comprehensive goal of improving the efficiency, low cost, and high quality of molten scrap steel converter smelting.

[0013] To achieve the above objectives, this invention provides a molten waste steel composition regulator, comprising a low-cost silicon-aluminum-calcium-carbon alloy, crystalline silicon cutting grade III abrasive, carbonaceous material, organic fiber, passivating lime, and a binder; the weight percentages of each component are as follows: low-cost silicon-aluminum-calcium-carbon alloy 5-15%, particle size ≤5mm; crystalline silicon cutting grade III abrasive 50-60%, particle size ≤0.10mm; carbonaceous material 10-20%, composed of one or two of biochar and semi-coke, particle size ≤0.15mm; organic fiber 2-5%, composed of one or two of waste paper fiber and plant fiber, fiber length ≤10mm, fiber diameter ≤1mm; passivating lime 15-25%, composed of metallurgical lime kiln dust and metallurgical lime screened material mixed in a weight ratio of 1:1, and passivated by spraying 0.5-1% of total organic silicone oil during the mixing process, CaO weight percentage content ≥80%, particle size ≤1mm; binder 1-3%, composed of one or two of corn starch and polyvinyl alcohol.

[0014] Furthermore, the silicon cutting grade 3 abrasive is a solid waste generated after solid-liquid separation and large particle SiC recovery of the slurry produced during the silicon cutting process, wherein the mass percentage content of metallic silicon is 50-70% and the mass percentage content of SiC is 20-30%.

[0015] Furthermore, the low-cost silicon-aluminum-calcium-carbon alloy is the low-cost silicon-aluminum-calcium-carbon alloy disclosed in Chinese patent "Ouyang Degang, Li Lingjun, Tong Gang, et al., A low-cost silicon-aluminum-calcium-carbon alloy and its preparation method, and its application in converter metallurgical heat replenishment, patent application number: 202210440479.5".

[0016] Furthermore, the biochar is a biochar powder prepared by high-temperature pyrolysis of agricultural and forestry biomass resources under low-oxygen conditions, with a fixed carbon content of ≥70%.

[0017] Furthermore, the semi-coke is semi-coke powder generated during the production and transportation of semi-coke, with a fixed carbon content of ≥80%.

[0018] Furthermore, the waste paper fiber is obtained by crushing recycled waste paper with a paper shredder and then pulverizing it with a pulverizer; the plant fiber is obtained by pulverizing wheat straw and rice straw with a pulverizer.

[0019] The specific steps of the preparation method of the molten waste steel conditioner of the present invention are as follows:

[0020] 1) Prepare low-cost silicon-aluminum-calcium-carbon alloy, crystalline silicon cutting grade III abrasive, carbonaceous materials, organic fibers, passivated lime and binder raw materials according to the raw material composition of the above regulator;

[0021] 2) Low-cost silicon-aluminum-calcium-carbon alloy is crushed and sieved using a 5mm mesh screen to obtain naturally graded granules with a particle size ≤5mm; crystalline silicon cutting grade III abrasive is sieved using a 0.10mm mesh screen to obtain powder with a particle size ≤0.10mm; biochar and semi-coke, or a mixture of both, are sieved using a 0.15mm mesh screen to obtain carbonaceous materials with a particle size ≤0.15mm; recycled waste paper is shredded using a paper shredder and then further pulverized using a crusher to obtain waste paper fibers with a fiber length ≤10mm and a fiber diameter ≤1mm; wheat straw and rice straw are pulverized using a crusher. Plant fibers with a fiber length ≤10mm and a fiber diameter ≤1mm are obtained. Metallurgical lime kiln dust and metallurgical lime are screened using a 1mm mesh screen and added to a closed vertical mixer at a weight ratio of 1:1. During mixing, 0.5–1% of the total weight of the metallurgical lime kiln dust and metallurgical lime is sprayed with organosilicon oil for passivation, resulting in passivated lime with a CaO weight percentage ≥80% and a particle size ≤1mm. A binder is obtained by mixing one or both of corn starch and polyvinyl alcohol.

[0022] 3) According to the weight percentage of the above-mentioned regulator, weigh each component of the various raw materials treated in step 2), add them to a vertical mixer, and mix for 10-15 minutes to obtain a mixture of molten waste steel composition regulator.

[0023] 4) Add the above-obtained mixture to a roller briquetting machine and dry press it into spherical bodies with a diameter of 20-35 mm. Pack the spherical bodies into a sealed package and put them into storage to obtain the finished product of the molten waste steel composition regulator of the present invention. Take samples to analyze the fixed carbon content, elemental silicon content and silicon carbide content in the finished product.

[0024] This invention also provides a method for applying a component modifier to molten steel waste, the specific steps of which are as follows:

[0025] 1) Based on production record data, confirm the amount of scrap steel added to the torpedo ladle or molten iron ladle; use the modifier disclosed in Chinese patent "Ouyang Degang, Sun Wei, Zhu Wanjun et al., Molten Scrap Steel Modifier and its Preparation Method and Application, Patent Application No.: 202210313316.0" to perform online modification of molten scrap steel and desulfurization and slag removal of molten iron; based on the temperature measurement and sampling analysis results after desulfurization and slag removal, confirm the weight, temperature and composition of the desulfurized molten scrap steel.

[0026] 2) Based on the differences in composition between the desulfurized molten scrap steel and the blast furnace molten iron, and the sampling and analysis results of the fixed carbon content, elemental silicon content, and silicon carbide content in the finished molten scrap steel composition regulator, calculate the required dosage W1 of the molten scrap steel composition regulator for adjusting the silicon content of molten iron, assuming a 50% recovery rate of elemental silicon and silicon carbide / compound silicon, and the difference between the required silicon content of the molten scrap steel and the silicon content of the blast furnace molten iron.

[0027] 3) Based on the dosage W1 of the molten scrap steel composition regulator, calculate the amount of fixed carbon and silicon carbide compound carbon introduced under the corresponding dosage of the molten scrap steel composition regulator.

[0028] 4) Based on the amount of scrap steel added to the converter, the temperature of the molten scrap steel after desulfurization, the amount of fixed carbon and silicon carbide compound carbon introduced after the addition of the molten scrap steel composition regulator, and the calculated value of the silicon content in the molten iron, the converter static heat balance model is used to calculate the required heat supplement under the corresponding converter scrap steel addition conditions; and based on the heat supplement and the composition of the molten scrap steel composition regulator, the amount of heat supplement W2 added by the molten scrap steel composition regulator is calculated.

[0029] 5) Based on the calculated amount of molten scrap steel composition regulator W1 and the amount of reheating required for adjusting the silicon composition of molten iron and reheating the high scrap steel ratio smelting in the converter, calculate the total amount of molten scrap steel composition regulator required W = W1 + W2.

[0030] 6) According to the calculated total amount W of molten scrap steel composition regulator, spread W of molten scrap steel composition regulator on the surface of the molten iron ladle after desulfurization and slag removal. After the addition is completed, transfer it to the converter for iron addition and smelt it according to the high scrap steel ratio smelting process under normal molten iron converter smelting heat balance conditions to complete the high scrap steel ratio high-quality, high-efficiency and low-cost smelting of molten scrap steel in the converter.

[0031] The beneficial effects of this invention are:

[0032] In the current context of high scrap ratio smelting, the amount of scrap added in a single converter process is limited by the volume of the scrap trough, as well as the constraints of converter heat balance and production rhythm. This restricts the effective increase of the scrap ratio in converter smelting, leading to the development of scrap addition technology for molten iron. However, in actual production, difficulties exist in desulfurizing and slag removal from molten scrap, large fluctuations in the quality of molten iron entering the furnace, and low chemical and physical heat. This results in severe heat deficiency under high scrap ratio smelting conditions in converters, and converter blowing leads to high carbon-oxygen accumulation and sulfur reversion in tapped steel. Although the Chinese patent "Ouyang Degang, Sun Wei, Zhu Wanjun et al., Molten Scrap Iron Modifier and Its Preparation Method and Application, Patent Application No.: 202210313316.0" effectively solves the problem of difficult desulfurization and slag removal from molten scrap, it fails to address the issues of large fluctuations in molten iron composition and reduced chemical heat caused by the oxidation loss of alloying elements in the molten iron. To address the problem of insufficient heat in converter smelting of molten scrap steel, although the use of in-furnace heating agents and molten scrap steel has made up for some of the insufficient heat in the furnace, the accumulation of residual and harmful elements in the cheap heating agents and conventional molten scrap steel makes it difficult to control the composition of the molten steel. At the same time, the time spent on the processes of adding in-furnace heating agents and molten scrap steel, heating up, melting and oxidation combustion of heating elements leads to a longer converter smelting cycle, which restricts the efficient smelting production of converters.

[0033] This invention, through the introduction of a low-cost silicon-aluminum-calcium-carbon alloy into a molten scrap steel composition regulator, and the limitation of its high content of Si, Al, Ca, and C alloying elements, as well as the content of harmful and difficult-to-oxidize alloying elements, not only achieves the dissolution and replenishment of alloying elements in the molten iron, improving the chemical heat of the molten iron entering the furnace, and reducing the enrichment of harmful and difficult-to-remove residual elements, but also achieves deep desulfurization of Ca alloying elements in the molten iron, improving the stability of sulfides in the desulfurization slag and inhibiting sulfur reversion in the converter. By selecting the crystalline silicon cutting grade III sand in the regulator, the content of harmful and difficult-to-remove residual elements in the regulator is reduced, improving the purity of the molten steel produced in the converter. Through the silicon- and carbon-enhancing effects of the high content of elemental silicon and silicon carbide in the crystalline silicon cutting grade III sand, the silicon and carbon content of the molten scrap steel can be controlled and adjusted, further improving the chemical heat of the molten iron entering the converter. The system utilizes dissolved residual elemental silicon and silicon carbide, which are high-calorific-value heat-generating components, to achieve efficient and high-energy-density heat replenishment within the converter furnace. By selecting biochar and semi-coke as carbonaceous materials in the regulator, the amount of harmful elements introduced and their bonding energy are reduced, promoting the decomposition and removal rate of harmful elements while simultaneously lowering the cost of carbonaceous materials and increasing the utilization rate of green carbon resources. Furthermore, by using waste paper fiber, wheat straw, and rice straw plant fiber as organic fibers in the regulator, the reuse rate of waste paper, wheat straw, and rice straw is increased, reducing costs and environmental pollution. Simultaneously, the reinforcing and toughening effect of organic fibers improves the room-temperature strength of the molten scrap steel composition regulator spheres, its resistance to high-temperature cracking during transportation and addition to the molten iron surface, and reduces dust pollution during the transportation and use of the molten scrap steel composition regulator. By adding passivated lime obtained through mixing metallurgical lime kiln dust and metallurgical lime screen underfill with organosilicon oil in the regulator, the cost of passivated lime is reduced, lime is prevented from becoming damp and pulverized, the activity of passivated lime is improved, the alkalinity of the regulator is controlled, the slag formation rate of the regulator is increased, the air oxidation of alloying elements in the molten iron surface regulator is prevented, the alloy dissolution and alloy utilization rate are increased, and high-quality utilization of secondary resources in the metallurgical lime production process is achieved. By selecting one or a mixture of corn starch and polyvinyl alcohol as the pelletizing binder of the regulator, the dry pressing pelleting strength of the regulator is improved, and dust pollution caused by the pulverization of the regulator during transportation is prevented.

[0034] The method for preparing the molten waste steel composition regulator of this invention reduces the enrichment of harmful elements and difficult-to-oxidize residual elements in the regulator through the rational selection of various raw materials. Pretreatment techniques for various raw materials ensure the particle size and technical performance requirements of the various raw materials in the regulator of this invention. Stirring and mixing processes and dry pressing pelletizing ensure the uniformity of the finished product's performance, the strength of the pellet bonding, and the required pellet diameter, preventing pulverization and dust generation during packaging, transportation, and use, and improving the effective utilization rate of the regulator. In the application method of the molten waste steel composition regulator of this invention, the Chinese patent "Ouyang Degang, Sun Wei, Zhu Wanjun, et al., Molten Waste Steel Modifier and its Preparation Method and Application" is adopted. The modifier disclosed in application number 202210313316.0 is used for online molten iron modification and desulfurization slag removal of molten scrap steel, ensuring the quality of desulfurization slag removal of molten scrap steel. Through precise calculation of the appropriate amount of modifier and the method of adding it to the molten iron ladle, the modifier's heating, melting, and alloy dissolution composition adjustment functions are guaranteed after its addition. This promotes the slag formation outside the furnace and the gasification removal of harmful elements, avoiding the time-consuming process of adding, heating, melting, alloy dissolution, and oxidation in the converter, thus shortening the converter smelting cycle. This invention achieves the efficient and low-cost application of the modifier, and realizes the comprehensive objectives of improving the converter scrap ratio, smelting efficiency, in-furnace alloy oxidation exothermic reheating efficiency, and improving the quality of molten steel produced from the converter.

[0035] Using the molten scrap steel composition regulator and application method of this invention, an industrial-scale smelting test of a high scrap steel ratio converter with multiple processes was conducted. By strictly following the usage steps in the application method, online composition control of molten scrap steel after desulfurization and slag removal was achieved. Furthermore, by adding the full amount of molten iron level regulator to the molten iron ladle, the regulator was able to replenish heat and raise the temperature in the converter. This achieved the expected goal of reasonable control of alloy composition after desulfurization and slag removal of molten scrap steel and efficient, high-quality, and low-cost smelting of high scrap steel ratio in the converter. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments to facilitate a clearer understanding of the present invention, but these embodiments do not constitute a limitation on the present invention.

[0037] This invention relates to a molten waste steel composition regulator, comprising a low-cost silicon-aluminum-calcium-carbon alloy, crystalline silicon cutting grade III abrasive, carbonaceous materials, organic fibers, passivating lime, and a binder. The weight percentages of each component are as follows: low-cost silicon-aluminum-calcium-carbon alloy 5-15%, particle size ≤5mm; crystalline silicon cutting grade III abrasive 50-60%, particle size ≤0.10mm; carbonaceous materials 10-20%, composed of one or two of biochar and semi-coke, particle size ≤0.15mm; organic fibers 2-5%, composed of one or two of waste paper fibers and plant fibers, fiber length ≤10mm, fiber diameter ≤1mm; passivating lime 15-25%, composed of metallurgical lime kiln dust and metallurgical lime screened material mixed in a 1:1 weight ratio, with 0.5-1% of total organic silicone oil sprayed during the mixing process for passivation, CaO weight percentage ≥80%, particle size ≤1mm; and binder 1-3%, composed of one or a mixture of corn starch and polyvinyl alcohol. The three-stage silicon cutting abrasive is a solid waste product generated during the silicon cutting process after solid-liquid separation and large-particle SiC recovery. The abrasive contains 50-70% metallic silicon and 20-30% SiC by mass. The low-cost silicon-aluminum-calcium-carbon alloy is the low-cost silicon-aluminum-calcium-carbon alloy disclosed in Chinese patent "Ouyang Degang, Li Lingjun, Tong Gang, et al., A low-cost silicon-aluminum-calcium-carbon alloy and its preparation method, application in converter metallurgical heat replenishment, patent application number: 202210440479.5". The biochar is biochar powder prepared from agricultural and forestry biomass resources through high-temperature pyrolysis in a low-oxygen environment, with a fixed carbon content ≥70%. The semi-coke is semi-coke powder generated during its production and transportation, with a fixed carbon content ≥80%. The waste paper fiber is obtained by crushing recycled waste paper using a paper shredder and then a pulverizer; the plant fiber is obtained by pulverizing wheat straw and rice straw.

[0038] The specific steps of the method for preparing the molten waste steel modifier of the present invention are as follows:

[0039] 1) Prepare low-cost raw materials such as silicon-aluminum-calcium-carbon alloy, crystalline silicon cutting grade III abrasive, carbonaceous materials, organic fibers, passivating lime, and binders according to the raw material composition of the molten waste steel composition regulator of the present invention.

[0040] 2) Low-cost silicon-aluminum-calcium-carbon alloy is crushed and sieved using a 5mm mesh screen to obtain naturally graded granules with a particle size ≤5mm; crystalline silicon cutting grade III abrasive is sieved using a 0.10mm mesh screen to obtain powder with a particle size ≤0.10mm; biochar and semi-coke, or a mixture of both, are sieved using a 0.15mm mesh screen to obtain carbonaceous materials with a particle size ≤0.15mm; recycled waste paper is shredded using a paper shredder and then further pulverized using a crusher to obtain waste paper fibers with a fiber length ≤10mm and a fiber diameter ≤1mm; wheat straw and rice straw are pulverized using a crusher. Plant fibers with a fiber length ≤10mm and a fiber diameter ≤1mm are obtained. Metallurgical lime kiln dust and metallurgical lime are screened using a 1mm mesh screen and added to a closed vertical mixer at a weight ratio of 1:1. During mixing, 0.5–1% of the total weight of the metallurgical lime kiln dust and metallurgical lime is sprayed with organosilicon oil for passivation, resulting in passivated lime with a CaO weight percentage ≥80% and a particle size ≤1mm. A binder is obtained by mixing one or both of corn starch and polyvinyl alcohol.

[0041] 3) Based on the mass percentages of low-cost silicon-aluminum-calcium-carbon alloy, crystalline silicon cutting grade III sand, carbonaceous materials, organic fibers, passivated lime, and binder in the molten waste steel composition regulator of the present invention, weigh each component using the various raw materials after the second step of treatment, add them to a vertical mixer, and mix for 10-15 minutes to obtain the molten waste steel composition regulator mixture.

[0042] 4) Add the above-obtained mixture to a high-strength double-roller briquetting machine and dry press it into spherical bodies with a diameter of 20-35mm. Pack the spherical bodies into a sealed package and put them into storage to obtain the finished product of the molten waste steel composition regulator of the present invention. Take samples to analyze the fixed carbon content, elemental silicon content and silicon carbide content in the finished product.

[0043] The specific steps of the application method of the molten steel composition regulator of the present invention are as follows:

[0044] 1) Based on production record data, confirm the amount of scrap steel added to the torpedo ladle or molten iron ladle; use the modifier disclosed in Chinese patent "Ouyang Degang, Sun Wei, Zhu Wanjun et al., Molten Scrap Steel Modifier and its Preparation Method and Application, Patent Application No.: 202210313316.0" to perform online modification of molten scrap steel and desulfurization and slag removal of molten iron; based on the temperature measurement and sampling analysis results after desulfurization and slag removal, confirm the weight, temperature and composition of the desulfurized molten scrap steel.

[0045] 2) Based on the differences in composition between the desulfurized molten scrap steel and the blast furnace molten iron, and the sampling and analysis results of the fixed carbon content, elemental silicon content, and silicon carbide content in the finished molten scrap steel composition regulator, calculate the required dosage W1 of the molten scrap steel composition regulator for adjusting the silicon content of molten iron, assuming a 50% recovery rate of elemental silicon and silicon carbide / compound silicon, and the difference between the required silicon content of the molten scrap steel and the silicon content of the blast furnace molten iron.

[0046] 3) Based on the dosage W1 of the molten scrap steel composition regulator, calculate the amount of fixed carbon and silicon carbide compound carbon introduced under the corresponding dosage of the molten scrap steel composition regulator.

[0047] 4) Based on the amount of scrap steel added to the converter, the temperature of the molten scrap steel after desulfurization, the amount of fixed carbon and silicon carbide compound carbon introduced after the addition of the molten scrap steel composition regulator, and the calculated value of the silicon content in the molten iron, the converter static heat balance model is used to calculate the required heat supplement under the corresponding converter scrap steel addition conditions; and based on the heat supplement and the composition of the molten scrap steel composition regulator, the amount of heat supplement W2 added by the molten scrap steel composition regulator is calculated.

[0048] 5) Based on the calculated amount of molten scrap steel composition regulator W1 and the amount of reheating required for adjusting the silicon composition of molten iron and reheating the high scrap steel ratio smelting in the converter, calculate the total amount of molten scrap steel composition regulator required W = W1 + W2.

[0049] 6) According to the calculated total amount W of molten scrap steel composition regulator, spread W of molten scrap steel composition regulator on the surface of the molten iron ladle after desulfurization and slag removal. After the addition is completed, transfer it to the converter for iron addition and smelt it according to the high scrap steel ratio smelting process under normal molten iron converter smelting heat balance conditions to complete the high scrap steel ratio high-quality, high-efficiency and low-cost smelting of molten scrap steel in the converter.

[0050] Using the molten scrap steel composition regulator and application method of this invention, industrial-scale smelting tests with high scrap steel ratios in 100-ton, 150-ton, 200-ton, and 250-ton converters were conducted. The regulator disclosed in Chinese patent "Ouyang Degang, Sun Wei, Zhu Wanjun et al., Molten Scrap Steel Modifier and its Preparation Method and Application, Patent Application No.: 202210313316.0" was used for online modification of molten scrap steel and desulfurization and slag removal, improving the quality of desulfurization and slag removal. Through precise calculation of the regulator dosage and strict adherence to the application steps, online composition control of the molten scrap steel after desulfurization and slag removal was achieved. Furthermore, the full addition of the molten iron level regulator in the ladle enabled reheating and temperature increase within the converter, achieving the expected goals of reasonable control of alloy composition after desulfurization and slag removal of the molten scrap steel and efficient, high-quality, and low-cost smelting with a high scrap steel ratio in the converter.

Claims

1. A composition modifier for molten steel scrap, characterized in that: It includes, by weight percentage, 5-15% low-cost silicon-aluminum-calcium-carbon alloy, 50-60% crystalline silicon cutting grade III abrasive, 10-20% carbonaceous materials, 2-5% organic fibers, 15-25% passivating lime and 1-3% binder. Among them, the carbonaceous material is composed of one or two of biochar and semi-coke, with a particle size ≤0.15mm; Organic fiber is composed of one or two of waste paper fiber and plant fiber, with a fiber length ≤10mm and a fiber diameter ≤1mm. Passivated lime is composed of dust from metallurgical lime kilns and screened metallurgical lime in a 1:1 weight ratio. During the mixing process, 0.5-1% of total organic silicone oil is sprayed for passivation. The CaO weight percentage content is ≥80% and the particle size is ≤1mm. The binder is composed of one or a mixture of corn starch and polyvinyl alcohol; The silicon cutting grade 3 abrasive is a solid waste generated after solid-liquid separation and large particle SiC recovery of the slurry produced during the silicon cutting process. The mass percentage content of metallic silicon is 50-70%, and the mass percentage content of SiC is 20-30%.

2. The molten steel composition regulator according to claim 1, characterized in that: The biochar is a powder prepared by high-temperature pyrolysis of agricultural and forestry biomass resources under low-oxygen conditions, with a fixed carbon content of ≥70%.

3. The molten steel composition regulator according to claim 1, characterized in that: The semi-coke is semi-coke powder generated during the production and transportation of semi-coke, with a fixed carbon content of ≥80%.

4. The molten steel composition regulator according to claim 1, characterized in that: The waste paper fiber is obtained by crushing recycled waste paper in a paper shredder and then pulverizing it in a pulverizer; the plant fiber is obtained by pulverizing wheat straw and rice straw in a pulverizer.

5. A method for preparing a molten steel composition regulator, characterized in that: The specific process of the preparation method is as follows: 1) Prepare materials in accordance with the raw material composition of the molten waste steel composition regulator according to claim 1, including low-cost silicon-aluminum-calcium-carbon alloy, crystalline silicon cutting grade III sand, carbonaceous materials, organic fibers, passivated lime and binder. 2) The low-cost silicon-aluminum-calcium-carbon alloy is crushed and screened using a 5mm mesh screen to obtain granular material with a particle size ≤ 5mm and natural gradation; the crystalline silicon cutting grade three abrasive is screened using a 0.10mm mesh screen to obtain powder with a particle size ≤ 0.10mm. One or a mixture of biochar and semi-coke screened through a 0.15mm mesh screen is used to obtain carbonaceous materials with a particle size ≤0.15mm; recycled waste paper is selected, shredded using a paper shredder, and then crushed using a pulverizer to obtain waste paper fibers with a fiber length ≤10mm and a fiber diameter ≤1mm; wheat straw and rice straw are selected and crushed using a pulverizer to obtain plant fibers with a fiber length ≤10mm and a fiber diameter ≤1mm; metallurgical lime kiln dust and metallurgical lime screened through a 1mm mesh screen are used, and the materials are added to a closed vertical mixer at a weight ratio of 1:1 for mixing. During the mixing process, 0.5~1% of the total amount of metallurgical lime kiln dust and metallurgical lime is sprayed with organosilicon oil for passivation to obtain passivated lime with a CaO weight percentage content ≥80% and a particle size ≤1mm; one or a mixture of corn starch and polyvinyl alcohol is used to obtain a binder. 3) Weigh each component of the raw material after step 2) according to the weight percentage of the molten waste steel composition regulator in claim 1, add them to a vertical mixer, and mix for 10-15 minutes to obtain a mixture; 4) Add the mixture obtained in step 3) into a double roller briquetting machine and dry press it into spherical bodies with a diameter of 20~35mm. Pack the spherical bodies into a sealed package and put them into storage to obtain a molten steel composition regulator.

6. A method for applying the molten steel composition regulator as described in claim 1, characterized in that: The specific steps of the application method are as follows: 1) Based on production record data, confirm the amount of scrap steel added to the torpedo ladle or molten iron ladle; use a modifier to perform online modification of molten scrap steel and desulfurization and slag removal of molten iron; based on the temperature measurement and sampling analysis results after desulfurization and slag removal, confirm the weight, temperature, and composition of the molten scrap steel after desulfurization. 2) Based on the differences between the composition of molten scrap steel and the composition of blast furnace iron after desulfurization, as well as the sampling and analysis results of the fixed carbon content, elemental silicon content, and silicon carbide content in the finished molten scrap steel composition regulator, calculate the amount of molten scrap steel composition regulator required for adjusting the silicon content of molten iron, W1, according to the recovery rate of elemental silicon and silicon carbide compound silicon of 50% and the difference between the silicon content of molten scrap steel and the silicon content required for blast furnace iron. 3) Based on the dosage W1 of the molten scrap steel composition regulator, calculate the amount of fixed carbon and silicon carbide compound carbon introduced under the corresponding dosage of the molten scrap steel composition regulator; 4) Based on the amount of scrap steel added to the converter, the temperature of the molten scrap steel after desulfurization, the amount of fixed carbon and silicon carbide compound carbon introduced after the addition of the molten scrap steel composition regulator, and the calculated value of the silicon content in the molten iron, the converter static heat balance model is used to calculate the required heat supplement under the corresponding converter scrap steel addition conditions; and based on the heat supplement and the composition of the molten scrap steel composition regulator, the amount of heat supplement W2 added by the molten scrap steel composition regulator is calculated. 5) Based on the calculated amount of molten scrap steel composition regulator W1 and heat replenishment required for adjusting the silicon composition of molten iron and for reheating the high scrap steel ratio smelting in the converter, calculate the total amount of molten scrap steel composition regulator required W = W1 + W2. 6) According to the calculated total amount W of molten scrap steel composition regulator, spread and add W of molten scrap steel composition regulator to the surface of the molten iron ladle after desulfurization and slag removal. After the addition is completed, transfer it to the converter for iron mixing and smelting according to the high scrap steel ratio smelting process under the heat balance conditions of molten iron converter smelting.