Stabilizer for electric furnace foaming slag with synergistic utilization of red mud and steel slag and preparation method thereof

Abstract

The present application relates to the technical field of auxiliary materials for electric furnace smelting, in particular to an electric furnace foamed slag stabilizer for synergistically utilizing red mud and steel slag and a preparation method thereof. The present application aims to solve the technical problems of poor foaming stability, high cost and low utilization rate of solid waste of the existing electric furnace foamed slag stabilizer. The stabilizer is composed of modified Bayer process red mud, fluorite, carbon powder and electric furnace steel slag according to weight parts. The red mud is subjected to magnetic separation to remove iron to Fe2O3≤6wt% and is ground to 150-200 mesh, which is matched with the particle sizes of fluorite, carbon powder and steel slag. The stabilizer is added at 1350-1450 DEG C in the oxidation period of the electric furnace. Al2O3 in the red mud and CaO and MgO in the steel slag synergistically form a stable foamed skeleton, and the carbon powder generates CO to continuously foam. The foamed slag obtained by the present application has a thickness of 300-400 mm, a duration of ≥25 min, a thermal efficiency increase of 15-20%, a cost reduction of 25-30%, and can high-value utilize the two kinds of solid waste of red mud and steel slag. The present application is suitable for smelting of electric furnaces with different capacities.

Description

Technical Field

[0001] This invention relates to the field of auxiliary materials technology for electric furnace smelting, specifically to an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag, and its preparation method. Background Technology

[0002] In electric arc furnace smelting, the formation of stable and thick foamed slag during the oxidation period plays a crucial role in encapsulating the electric arc, reducing heat radiation loss, enhancing slag-steel reaction, and improving dephosphorization and desulfurization efficiency. Currently, the foaming agents widely used in industry for electric arc furnace foamed slag are mainly composed of fluorite and carbon powder mixed in a mass ratio of 7:3 or 8:2. Some formulations add high-purity Al2O3 powder to the system to further improve foam stability.

[0003] However, the above-mentioned existing technical solutions have the following technical defects in practical applications: 1. Insufficient foam stability makes it difficult to meet the requirements of efficient smelting. While the traditional fluorite-carbon powder system can lower the slag melting point and surface tension through CaF2 and promote foaming, the resulting bubbles have uneven diameter distribution and a fragile foam structure, making them prone to breakage under the intense arc stirring and molten steel circulation of the electric furnace. The foam slag formed by this system typically lasts only 10–15 minutes and is about 200 mm thick, resulting in insufficient electrode embedment depth and an improvement in thermal efficiency of only 8%–12%. To improve foam stability, those skilled in the art generally believe that it is necessary to introduce high-purity Al2O3 as a stabilizer into the system, utilizing its high melting point to enhance the strength of the foam skeleton.

[0004] 2. The use of high-purity Al2O3 has led to a significant increase in costs. Influenced by the aforementioned technical concept that "high-purity Al2O3 is a necessary component for improving foam stability," existing technologies use the addition of high-purity Al2O3 powder (typically ≥99% purity) to improve the performance of foam slag. However, high-purity Al2O3 raw materials are expensive, and their addition increases the overall cost of electric furnace foam slag stabilizers by 40% to 50%, severely impacting the economic viability of this technical solution.

[0005] 3. Large quantities of metallurgical solid waste, such as red mud and steel slag, have not been utilized in a high-value-added and collaborative manner. Bayer process red mud (with a national stockpile exceeding 400 million tons, rich in 18wt%–25wt% Al2O3) and electric arc furnace steel slag (annual production exceeding 120 million tons, rich in CaO and MgO) are typical bulk solid wastes from the metallurgical industry. In existing technologies, red mud is mostly used for low-value-added building materials or simple landfilling, while large-scale stockpiling of steel slag not only occupies land but also poses environmental risks. Although some studies have attempted to use red mud as a dephosphorizing agent in steelmaking, or to co-prepare foamed lightweight soil with steel slag, or to recover iron resources, these applications have not addressed the formation mechanism of foamed slag under electric arc furnace smelting conditions, nor have they revealed the potential synergistic stabilizing effect between Al2O3 in red mud and CaO and MgO in steel slag in high-temperature slag. Those skilled in the art generally believe that impurities such as Fe2O3 and SiO2 in red mud will adversely affect the performance of foamed slag, thus exhibiting a technical bias against directly using red mud as a foamed slag stabilizer.

[0006] 4. Electric furnace foam slag stabilizer requires large dosage and has poor compatibility. Traditional electric arc furnace foam slag stabilizers are typically used at a dosage of 8–10 kg / t of steel, resulting in a cost of 20–25 yuan per ton of steel. Furthermore, existing formulations do not adequately consider the differences in molten pool depth and heat dissipation characteristics between electric arc furnaces of different capacities (e.g., small-capacity 50–100 t electric arc furnaces versus large-capacity 100–200 t electric arc furnaces), employing a "one-size-fits-all" approach. This leads to excessively thick foam slag and increased risk of phosphorus reversion in small-capacity electric arc furnaces, or uneven foam coverage and reduced protective effect in large-capacity electric arc furnaces. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag, and its preparation method. It can replace high-purity Al2O3, while realizing the high-value synergistic utilization of two solid wastes, red mud and steel slag, and improving the continuous stability and electric furnace compatibility of foam slag.

[0008] To achieve the above objectives, the present invention employs the following technical solution: An electric arc furnace foam slag stabilizer that synergistically utilizes red mud and steel slag comprises the following raw materials in parts by weight: 40-60 parts modified Bayer process red mud, 15-25 parts fluorite, 15-25 parts carbon powder, and 10-20 parts electric arc furnace steel slag; wherein the modified Bayer process red mud is Bayer process red mud that has been magnetically separated to remove iron until the Fe2O3 content is ≤6wt% and ground to 150-200 mesh; the particle size of the fluorite, carbon powder, and electric arc furnace steel slag is 150-200 mesh.

[0009] Furthermore, the Al2O3 content in the modified Bayer red mud is 18wt% to 25wt%.

[0010] Furthermore, the electric furnace slag contains 40wt% to 50wt% CaO, 5wt% to 8wt% MgO, and ≤1.5wt% P2O5.

[0011] Furthermore, the fluorite contains ≥90wt% CaF2 and ≤3wt% SiO2; the carbon powder contains ≥85wt% fixed carbon, ≤8wt% ash, and ≤5wt% volatile matter.

[0012] The above-mentioned method for preparing an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag includes the following steps: 1) The Bayer process red mud is subjected to magnetic separation to remove iron until the Fe2O3 content is ≤6wt%, and then ground to 150-200 mesh to obtain modified Bayer process red mud.

[0013] 2) Crush and grind the electric furnace slag to 150-200 mesh.

[0014] 3) Grind the fluorite and carbon powder to 150-200 mesh respectively.

[0015] 4) Weigh the modified Bayer process red mud, fluorite, carbon powder and electric furnace steel slag according to the stated weight proportions, mix them evenly, and discharge them to obtain the electric furnace foam slag stabilizer.

[0016] A method for using an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag is as follows: During the oxidation period of the electric furnace, when the temperature of molten steel is 1350-1450℃, the stabilizer is added to the electric furnace at a rate of 4-7 kg / t steel.

[0017] Furthermore, the stabilizer is added by mechanical feeding or spraying.

[0018] Furthermore, when the electric furnace capacity is between 50t and 100t, the amount of stabilizer added is 4-5 kg / t of steel; when the electric furnace capacity is between 100t and 200t, the amount of stabilizer added is 5-6 kg / t of steel; and when the electric furnace capacity is greater than 200t, the amount of stabilizer added is 6-7 kg / t of steel.

[0019] Compared with existing methods, the beneficial effects of the present invention are: 1. Significantly improves the stability and duration of foam residue. In this invention, the Al2O3 contained in the modified Bayer process red mud can form needle-like crystals in the slag of the electric furnace during the oxidation period at 1350–1450°C. These needle-like crystals, together with the low-melting-point anorthite generated by the reaction of SiO2 contained in the red mud itself and the CaO and MgO provided by the electric furnace steel slag, further react to generate a high-melting-point calcium aluminate three-dimensional network framework. This framework can effectively bind the CO bubbles generated by the reaction of carbon powder and molten steel, significantly inhibiting the merging and escaping of bubbles.

[0020] This invention utilizes the synergistic chemical effect of Al2O3 in red mud and CaO / MgO in steel slag to form a more robust and dense foam skeleton. Experimental data shows that, with a stabilizer addition of only 4–6 kg / t steel (a reduction of 25%–40% compared to the traditional 8–10 kg / t steel), the foam slag thickness can reach 300–400 mm, the stabilization time is ≥25 min, and the electrode embedment depth increases by 20%–30% (from approximately 150 mm in the traditional scheme to 180–195 mm). In contrast, the foam duration of the traditional fluorite-carbon powder scheme is only 10–15 min, and the thickness is approximately 200 mm.

[0021] 2. Significantly reduce production costs and achieve high-value utilization of solid waste. This invention breaks the technical prejudice that "high-purity Al2O3 must be used to obtain stable foam slag." Bayer process red mud, as a waste residue from the alumina industry, has a pretreatment cost of only 100-130 yuan / t, while the market price of high-purity Al2O3 typically reaches several thousand yuan / t. By using 40-60 parts of modified red mud to replace an equal amount of high-purity Al2O3, and simultaneously utilizing 10-20 parts of electric furnace steel slag, the production cost of the electric furnace foam slag stabilizer of this invention is reduced to 2100-2250 yuan / t, a 25%-30% reduction compared to the traditional solution's 3000-3200 yuan / t.

[0022] Meanwhile, each ton of electric arc furnace foam slag stabilizer can dispose of approximately 0.48 tons of Bayer process red mud and 0.15 to 0.25 tons of electric arc furnace steel slag, with a solid waste resource utilization rate of ≥90%.

[0023] 3. Improve the thermal efficiency of electric furnaces and reduce energy consumption and smelting cycle. In the stabilizer described in this invention, carbon powder (15-25 parts) reacts with oxygen in molten steel during the oxidation period to generate CO gas, with each kilogram of carbon powder producing 1.8-2.0 mg / kg of CO gas. 3 The CO provides a sufficient gas source for the foamed slag. Simultaneously, the CO combustion at the top of the foam layer releases heat (approximately 110 kJ / mol), which can compensate for 2%–3% of the heat loss during the electric furnace oxidation period. More importantly, the uniform and thick foamed slag can effectively encapsulate the electric arc, transferring more of the arc's radiated heat to the molten steel and slag, reducing heat loss from the furnace top and walls.

[0024] Theoretical analysis shows that for every 100mm increase in foam slag thickness, thermal efficiency can be improved by approximately 5%–8%. The 300–400mm foam slag produced by this invention improves thermal efficiency by 15%–20% compared to the traditional 200mm foam slag. Correspondingly, the energy consumption per ton of steel is reduced by 30–45 kWh (compared to only 10–20 kWh reduction in the traditional method), and the smelting cycle is shortened by 8–12 minutes.

[0025] 4. Significantly improves dephosphorization and desulfurization effects The introduction of electric arc furnace slag not only synergistically stabilizes the foam, but its rich content of CaO (40%–50%) and MgO (5%–8%) also effectively regulates the slag basicity. This invention stably controls the basicity of the foamed slag at 3.0–3.5, which falls precisely within the ideal basicity range for dephosphorization reactions during the electric arc furnace oxidation period. Simultaneously, the uniform and dense foamed slag increases the slag-steel contact area, enhancing the interfacial reaction kinetics.

[0026] Experimental data show that after using the stabilizer of this invention, the dephosphorization rate is >85%, the desulfurization rate is >60%, and the final P content of the molten steel is ≤0.045wt% and the S content is ≤0.040wt%, which fully meets the quality requirements of low carbon steel grades such as Q235B.

[0027] 5. Optimize dosage control to adapt to electric furnaces of different capacities. This invention ensures uniform mixing through particle size matching (all raw materials are 150-200 mesh), with a composition deviation of ≤3%, avoiding the foam "layering" phenomenon caused by insufficient local carbon powder. Simultaneously, it clarifies the optimal dosage for different capacity electric furnaces: 4-5 kg / t steel for small-capacity 50-100t furnaces with less heat dissipation in the molten pool; and 5-6 kg / t steel for large-capacity 100-200t furnaces with a larger heat dissipation area. This differentiated dosage control strategy avoids both insufficient dosage leading to poor foam protection and excessive dosage causing increased slag (15%-20%) and the risk of phosphorus reversion in molten steel (an increase in P content of 0.005%-0.01%), achieving synergistic optimization of foam slag thickness and smelting indicators.

[0028] 6. Form a closed-loop circular economy model of "smelting-solid waste-remelting". The electric arc furnace slag used in this invention is itself a byproduct of electric arc furnace smelting. By recycling and processing it, it can be reused in the same electric arc furnace for foam slag control, realizing a circular utilization path of steel slag "from the electric arc furnace and back to the electric arc furnace." Combined with the disposal of red mud, this technical solution provides a feasible and high-value-added solution for the resource utilization of bulk solid waste in the metallurgical industry, with significant environmental benefits and industrial promotion value. Detailed Implementation

[0029] This invention discloses an electric arc furnace foam slag stabilizer that synergistically utilizes red mud and steel slag, and its preparation method. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0030] This invention provides an electric arc furnace foam slag stabilizer that synergistically utilizes red mud and steel slag, along with its preparation and application methods. The core design concept of this invention lies in: magnetically separating and removing iron from Bayer process red mud, finely grinding and modifying it, utilizing its rich Al2O3 as a foam stabilizer, compounding fluorite as a fluxing agent and viscosity reducer, and using carbon powder as a CO foaming source, while synergistically utilizing electric arc furnace steel slag to supplement CaO and MgO to stabilize the foam skeleton; adding it during the electric arc furnace oxidation period, the synergistic effect of Al2O3 with CaO and MgO constructs a stable foam skeleton, while the carbon powder reacts with oxygen in the molten steel to continuously generate CO gas to fill the skeleton, thereby achieving a dual improvement in foam slag thickness and thermal efficiency.

[0031] (a) Raw material composition and proportion The electric furnace foam slag stabilizer is composed of the following raw materials in parts by weight: 40-60 parts modified Bayer process red mud, 15-25 parts fluorite, 15-25 parts carbon powder, and 10-20 parts electric furnace steel slag.

[0032] (II) The core functions and physicochemical properties of each raw material 1. Modified Bayer process red mud, at a dosage of 40-60 parts by weight, is used as a foam stabilizer and solid waste carrier.

[0033] Its main functions include: First, stabilizing the foam structure. Al2O3 (18wt%–25wt%) in red mud forms needle-like crystals in slag at 1350–1450℃, combining with silicates in the slag to construct a three-dimensional foam skeleton, preventing bubble merging and escape, thus extending the foam duration from the traditional 8–10 minutes to over 25 minutes. Second, adjusting slag viscosity. SiO2 (15wt%–20wt%) in red mud reacts with CaO in the slag to form low-melting-point anorthite (melting point approximately 1250℃), reducing slag viscosity from the traditional 1.8 Pa·s to 1.2–1.4 Pa·s, optimizing foam fluidity. Third, cost reduction and environmental protection. The pretreatment cost of red mud is only 100–130 yuan / t. After replacing pure Al2O3 and some fluorite, the cost of electric arc furnace foam slag stabilizer is reduced by 25%–30%, and each ton of electric arc furnace foam slag stabilizer can absorb approximately 0.48 tons of red mud.

[0034] The key modification conditions for the modified Bayer red mud are: after magnetic separation to remove iron, the Fe2O3 content is ≤6wt% to avoid Fe element interfering with the formation of the foam skeleton; and it is ground to 150-200 mesh to achieve a specific surface area of ​​3.0-4.5m². 2 / g, ensuring rapid dispersion of Al2O3 in the slag.

[0035] 2. Fluorite, used in amounts of 15-25 parts by weight, as a flux and foam optimizer.

[0036] Its main functions include: First, lowering the melting point of slag. Fluorite contains ≥90wt% CaF2, which can break the Si-O bonds in the slag, reducing the melting point from 1450℃ to 1250–1300℃, providing a suitable temperature range for foam formation. Second, improving foaming efficiency. CaF2 can reduce the surface tension of the slag from 0.5N / m to 0.35–0.4N / m, making it easier for the CO gas generated by carbon powder to form fine bubbles (1–3mm in diameter), increasing the porosity of the foamed slag to 70%–80%.

[0037] The selection criteria are: CaF2 content ≥ 90wt%, SiO2 content ≤ 3wt%, to avoid excessive SiO2 leading to increased slag acidity and affecting foam stability; particle size matching red mud (150-200 mesh) to ensure uniform mixing with other raw materials and avoid uneven foam due to insufficient local fluxing.

[0038] 3. Toner, used in amounts of 15-25 parts by weight, as a foaming agent and energy supplement.

[0039] Its main functions include: First, continuous foaming. The carbon powder has a fixed carbon content of ≥85%, which reacts with oxygen (0.06%~0.10%) in the molten steel during the oxidation period to generate CO gas. The reaction formula is: C + [O] = CO↑. Each kilogram of carbon powder can generate 1.8~2.0m³ of CO gas. 3 The CO provides a sufficient gas source for the foam. Secondly, it assists in heating. The heat released by CO combustion (approximately 110 kJ / mol) can compensate for the 2% to 3% heat loss during the oxidation period of the electric furnace, helping to maintain the temperature of the molten steel.

[0040] The selection criteria are: ash content ≤ 8wt%, to avoid excessive SiO2 and Al2O3 in the ash increasing the viscosity of the slag; volatile matter ≤ 5%, to prevent the volatile matter from escaping at high temperatures, causing bubble rupture and affecting foam stability.

[0041] 4. Electric furnace steel slag, used in amounts of 10-20 parts by weight, as a synergistic stabilizer and recycling carrier.

[0042] Its main functions include: First, synergistically stabilizing foam. Electric arc furnace slag contains 40wt%–50wt% CaO and 5wt%–8wt% MgO, which react with Al2O3 in red mud to form calcium aluminates (such as Ca...). 12 Al 14 O 33First, it enhances the strength of the foam skeleton, improves the impact resistance of the foam slag, and reduces the thickness by ≤10% after being disturbed by molten steel. Second, it adjusts the slag basicity. The steel slag basicity (CaO / SiO2) is 2.5-3.0, which can control the overall basicity of the foam slag at 3.0-3.5, meeting the dephosphorization requirements during the oxidation period (dephosphorization rate >85%). Third, it promotes recycling. It realizes a closed-loop cycle of steel slag "smelting → electric furnace foam slag stabilizer → remelting", increasing the comprehensive utilization rate of solid waste to over 90%.

[0043] The selection criteria are: P2O5 content ≤ 1.5wt% to avoid phosphorus return in molten steel; crushed to 150-200 mesh to ensure uniform mixing with other raw materials and to fully exert synergistic effects.

[0044] The above four raw materials form a complete foaming system of "foaming-stabilization-optimization": red mud is responsible for stabilizing foam and disposing of solid waste, fluorite is responsible for fluxing and reducing viscosity, carbon powder is responsible for continuous foaming, and steel slag is responsible for synergistic stabilization and recycling.

[0045] (III) Control of key process parameters 1. Raw material particle size control The particle size of all raw materials is controlled within 150–200 mesh. Within this particle size range, the specific surface area of ​​the particles is 3.0–4.5 m². 2 The powder density is 1.4 to 1.6 times that of 100-150 mesh particles, accelerating the reaction rate with slag by 40% to 50% and shortening the foam start-up time to 5 to 8 minutes. The four raw materials have consistent particle size, with a composition deviation of ≤3% after mixing, avoiding localized carbon powder deficiency that could lead to foam "discontinuities" (thickness difference > 50 mm). The powder bulk density is 1.4 to 1.7 g / cm³. 3 It is compatible with both jet feeding and mechanical feeding methods (bulk density < 1.4 g / cm³ when the particle size is too fine > 200 mesh). 3 Easily damaged by flying particles; bulk density > 1.7 g / cm³ when particle size is too coarse (<150 mesh). 3 (Easily deposited at the furnace bottom).

[0046] 2. Timing of addition and control of molten steel temperature The stabilizer is added during the oxidation period of the electric furnace. During the oxidation period, the oxygen content of the molten steel is sufficient (0.06% to 0.10%), allowing the carbon powder to fully react and generate CO. Furthermore, the oxidation period requires foamed slag to enhance dephosphorization (foamed slag increases the slag-steel contact area), which highly matches the process requirements. If added during the reduction period, the oxygen content of the molten steel is <0.005wt%, the carbon powder reaction rate is <40%, and the foaming effect is poor.

[0047] When adding the slag, the temperature of the molten steel should be controlled at 1350–1450℃. Within this temperature range, the slag is in a molten and flowing state (viscosity 1.2–1.4 Pa·s), which makes it easy to form stable foam. If the temperature is below 1350℃, the slag viscosity is >1.6 Pa·s, and the bubbles are difficult to diffuse. If the temperature is above 1450℃, the slag is too fluid, and the foam is easy to break.

[0048] 3. Dosage control and capacity matching The stabilizer is added at a rate of 4–6 kg / t of steel. At this dosage, 7.2–12 m³ of CO gas can be generated. 3 The combined effect of various raw materials forms a foamy slag with a thickness of 300-400mm. If the dosage is less than 4kg / t of steel, the foamy slag thickness is <250mm, and the thermal efficiency is improved by less than 15%; if the dosage is more than 6kg / t of steel, the slag amount increases by 15%-20%, which can easily lead to phosphorus reversion in the molten steel (P content increases by 0.005wt%-0.01wt%).

[0049] The adaptation schemes for electric arc furnaces of different capacities are as follows: For small-capacity electric arc furnaces of 50-100t, where the heat dissipation of the molten pool is less, a steel dosage of 4-5 kg / t is used; for large-capacity electric arc furnaces of 100-200t, where the heat dissipation area of ​​the molten pool is larger, a steel dosage of 5-6 kg / t is used to ensure uniform foam coverage; for ultra-large-capacity electric arc furnaces of 200t and above, where the molten pool area is further expanded, a steel dosage of 6-7 kg / t is used to ensure better foam coverage.

[0050] (iv) Preparation method The preparation method of the above-mentioned electric furnace foam slag stabilizer includes the following steps: (1) The Bayer red mud is subjected to magnetic separation to remove iron until the Fe2O3 content is ≤6wt%, and then ground to 150-200 mesh to obtain modified Bayer red mud; (2) Crush and grind the electric furnace steel slag to 150-200 mesh; (3) Grind the fluorite and carbon powder to 150-200 mesh respectively; (4) Weigh the modified Bayer red mud, fluorite, carbon powder and electric furnace steel slag according to the weight parts, put them into the mixing equipment and stir and mix them evenly, and then discharge them to obtain the electric furnace foam slag stabilizer.

[0051] To make the technical solution and beneficial effects of the present invention clearer, the present invention will be described in detail below with reference to specific embodiments. In the following embodiments, unless otherwise specified, the content of each component is a mass percentage (i.e., the sum of the weights of all components is 100%). The following embodiments are only used to illustrate the feasibility of the present invention and should not be construed as limiting the scope of protection of the present invention. All equivalent substitutions or improvements made based on the technical concept of the present invention fall within the scope of protection of the present invention.

[0052] Example 1:

[0053] This embodiment provides an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag, suitable for applications in small-capacity electric furnaces of 50-100t and the smelting of Q235B low-carbon steel.

[0054] (1) Raw material pretreatment: Bayer red mud (Al2O3 content 22wt%) was subjected to magnetic separation to remove iron, reducing the Fe2O3 content to 5.2%, and then finely ground to 180 mesh for later use.

[0055] Take electric furnace steel slag (CaO content 45wt%, MgO content 6wt%, P2O5 content 1.2wt%), crush and grind it to 180 mesh, and set it aside.

[0056] Take fluorite (CaF2 content 92wt%, SiO2 content ≤3wt%), grind it to 180 mesh, and set aside.

[0057] Take carbon powder (fixed carbon content 88wt%, ash content 6wt%, volatile matter 4wt%), grind it to 180 mesh, and set aside.

[0058] (2) Formula ratio: Weigh out the following ingredients by weight: 50 parts modified Bayer process red mud, 20 parts fluorite, 20 parts carbon powder, and 10 parts electric furnace steel slag, totaling 100 parts by weight. Add the weighed raw materials to a mixing device and mix thoroughly until homogeneous. Discharge the mixture to obtain the electric furnace foam slag stabilizer of this embodiment.

[0059] (3) Process parameters and usage methods: During the oxidation period of the electric furnace and when the temperature of the molten steel is 1380℃, the above stabilizer is added to the electric furnace at a rate of 4 kg / t of steel, and is added evenly into the furnace using a mechanical feeding method.

[0060] (4) Implementation results: Testing revealed that the foamed slag formed in this embodiment had a thickness of 320 mm, a stable duration of 28 minutes, and an electrode embedment depth of 185 mm. The electric furnace thermal efficiency was increased by 16%, the energy consumption per ton of steel was reduced by 35 kWh, and the smelting cycle was shortened by 9 minutes. The dephosphorization rate was 86%, the desulfurization rate was 62%, and the final P content in the molten steel was 0.042 wt% and the S content was 0.038 wt%, meeting the composition requirements of Q235B steel. The production cost of the electric furnace foamed slag stabilizer in this embodiment was 2100 yuan / ton, the foaming cost per ton of steel was 8.4 yuan, and each ton of stabilizer absorbed 0.48 tons of red mud and 0.15 tons of steel slag.

[0061] Example 2:

[0062] This embodiment provides an electric arc furnace foam slag stabilizer that synergistically utilizes red mud and steel slag, suitable for applications in 100-200t large-capacity electric arc furnaces and the smelting of Q235B low-carbon steel.

[0063] (1) Raw material pretreatment: Bayer red mud (Al2O3 content 20wt%) was subjected to magnetic separation to remove iron, reducing the Fe2O3 content to 5.8wt%, and then finely ground to 160 mesh for later use.

[0064] Take electric furnace steel slag (CaO content 48wt%, MgO content 7wt%, P2O5 content 1.0wt%), crush and grind it to 160 mesh, and set it aside.

[0065] Take fluorite (CaF2 content 93wt%, SiO2 content ≤3wt%), grind it to 160 mesh, and set aside.

[0066] Take carbon powder (fixed carbon content 86wt%, ash content 7wt%, volatile matter 3wt%), grind it to 160 mesh, and set aside.

[0067] (2) Formula ratio: Weigh out the following materials by weight: 60 parts modified Bayer process red mud, 15 parts fluorite, 15 parts carbon powder, and 10 parts electric furnace steel slag, totaling 100 parts by weight. Add the weighed materials to a mixing device and mix thoroughly until homogeneous. Discharge the mixture to obtain the electric furnace foam slag stabilizer of this embodiment.

[0068] (3) Process parameters and usage methods: During the oxidation period of the electric furnace and when the temperature of the molten steel is 1420℃, the above stabilizer is added to the electric furnace at a rate of 5 kg / t of steel, and is added to the furnace by injection.

[0069] (4) Implementation results: Testing showed that the foamed slag formed in this embodiment had a thickness of 360 mm, a stable duration of 30 min, and an electrode embedment depth of 190 mm. The electric furnace thermal efficiency was increased by 18%, the energy consumption per ton of steel was reduced by 40 kWh, and the smelting cycle was shortened by 10 min. The dephosphorization rate was 88%, the desulfurization rate was 65%, and the final P content of the molten steel was 0.038 wt% and the S content was 0.035 wt%, meeting the composition requirements of Q235B steel. The production cost of the electric furnace foamed slag stabilizer in this embodiment was 2150 yuan / t, the foaming cost per ton of steel was 10.75 yuan, and each ton of stabilizer absorbed 0.48 t of red mud and 0.20 t of steel slag.

[0070] Example 3:

[0071] This embodiment provides an electric arc furnace foam slag stabilizer that synergistically utilizes red mud and steel slag, suitable for applications in ultra-large volume electric arc furnaces of 200t or more and for smelting Q235B low carbon steel.

[0072] (1) Raw material pretreatment: Bayer red mud (Al2O3 content 25wt%) was subjected to magnetic separation to remove iron, reducing the Fe2O3 content to 4.5wt%, and then finely ground to 170 mesh for later use.

[0073] Take electric furnace steel slag (CaO content 50wt%, MgO content 8wt%, P2O5 content 0.8wt%), crush and grind it to 170 mesh, and set it aside.

[0074] Take fluorite (CaF2 content 95wt%, SiO2 content ≤3wt%), grind it to 170 mesh, and set aside.

[0075] Take carbon powder (fixed carbon content 90wt%, ash content 5wt%, volatile matter 2wt%), grind it to 170 mesh, and set aside.

[0076] (2) Formula ratio: Weigh out the following ingredients by weight: 40 parts modified Bayer process red mud, 25 parts fluorite, 25 parts carbon powder, and 10 parts electric furnace steel slag, totaling 100 parts by weight. Add the weighed raw materials to a mixing device and mix thoroughly until homogeneous. Discharge the mixture to obtain the electric furnace foam slag stabilizer of this embodiment.

[0077] (3) Process parameters and usage methods: During the oxidation period of the electric furnace and when the temperature of the molten steel is 1450℃, the above stabilizer is added to the electric furnace at a rate of 6.5 kg / t steel, using a combination of injection and mechanical feeding.

[0078] (4) Implementation results: Testing showed that the foamed slag formed in this embodiment had a thickness of 390 mm, a stable duration of 32 min, and an electrode embedment depth of 195 mm. The electric furnace thermal efficiency was increased by 20%, the energy consumption per ton of steel was reduced by 45 kWh, and the smelting cycle was shortened by 12 min. The dephosphorization rate was 90%, the desulfurization rate was 68%, and the final P content of the molten steel was 0.035 wt% and the S content was 0.032 wt%, meeting the composition requirements of Q235B steel. The production cost of the electric furnace foamed slag stabilizer in this embodiment was 2250 yuan / t, the foaming cost per ton of steel was 13.5 yuan, and each ton of stabilizer absorbed 0.48 t of red mud and 0.25 t of steel slag.

[0079] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag, characterized in that, It consists of the following raw materials in parts by weight: 40-60 parts of modified Bayer process red mud, 15-25 parts fluorite 15-25 parts toner 10-20 parts of electric furnace steel slag; The modified Bayer red mud is Bayer red mud that has been magnetically separated to remove iron until the Fe2O3 content is ≤6wt% and ground to 150-200 mesh; the particle size of the fluorite, carbon powder and electric furnace steel slag is 150-200 mesh.

2. The electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag according to claim 1, characterized in that, The modified Bayer red mud contains 18wt% to 25wt% Al2O3.

3. The electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag according to claim 1, characterized in that, The electric furnace slag contains 40wt% to 50wt% CaO, 5wt% to 8wt% MgO, and ≤1.5wt% P2O5.

4. The electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag according to claim 1, characterized in that, The fluorite contains ≥90wt% CaF2 and ≤3wt% SiO2; the carbon powder contains ≥85wt% fixed carbon, ≤8wt% ash, and ≤5wt% volatile matter.

5. A method for preparing an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag as described in any one of claims 1-4, characterized in that, Includes the following steps: 1) The Bayer process red mud is subjected to magnetic separation to remove iron until the Fe2O3 content is ≤6wt%, and then ground to 150-200 mesh to obtain modified Bayer process red mud; 2) Crush and grind the electric furnace slag to 150-200 mesh; 3) Grind the fluorite and carbon powder separately to 150-200 mesh; 4) Weigh the modified Bayer process red mud, fluorite, carbon powder and electric furnace steel slag according to the stated weight proportions, mix them evenly, and discharge them to obtain the electric furnace foam slag stabilizer.

6. A method for using an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag as described in any one of claims 1-4, characterized in that, Specifically as follows: During the oxidation period of the electric furnace, when the temperature of the molten steel is 1350-1450℃, the stabilizer is added to the electric furnace at a rate of 4-7 kg / t of steel.

7. The method for using an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag according to claim 6, characterized in that, The stabilizer is added by mechanical feeding or spraying.

8. The method for using an electric furnace foam slag stabilizer that synergistically utilizes red mud and steel slag according to claim 7, characterized in that, When the electric furnace capacity is between 50t and 100t, the amount of stabilizer added is 4-5 kg / t of steel; When the electric furnace capacity is between 100t and 200t, the amount of stabilizer added is 5-6 kg / t of steel; When the electric furnace capacity is greater than 200t, the amount of stabilizer added is 6~7kg / t steel.