A method for preparing a continuous casting ladle covering agent from used lithium cell bodies

Abstract

The present application belongs to the field of steelmaking functional materials and industrial solid waste resource utilization technology, and proposes a method for preparing a continuous casting ladle covering agent from used lithium battery cases, which comprises the steps of raw material pretreatment, proportioning, dry mixing and wet mixing, granulation molding, solidification and drying, and screening finished products. After the used aluminum-silicon lithium battery cases are manually removed, two-stage crushing, and magnetic separation to remove iron, superfine grinding is performed to obtain case powder with a particle size of less than 74 microns. The used lithium battery case powder, fused magnesia powder, quartz sand powder, light weight thermal insulation component, dolomite powder, and titanium white powder are added to a high-speed mixer in a predetermined ratio, dry mixed at 700-900 r / min for 30-50 min, and then wet mixed with inorganic binder and deionized water at 450-650 r / min for 20-40 min to form a uniform plastic mixture. The mixture is then molded into a centrifugal granulator, solidified, dried, and screened to obtain the finished product. The present application completely eliminates high-temperature pre-melting, simplifies the process, reduces energy consumption, improves efficiency, and requires less investment, and has obvious advantages in industrial application.

Description

Technical Field

[0001] This invention belongs to the technical field of steelmaking functional materials and industrial solid waste resource utilization. Specifically, it relates to a method for preparing a continuous casting ladle covering agent that is suitable for the high-temperature service environment of the ladle, has long-term heat preservation, anti-secondary oxidation, and deep purification of inclusions, without high-temperature pre-melting and using the sintered aluminum-silicon lithium battery box as the core raw material. The key is to optimize the slag performance and improve the quality of molten steel through the lithium component in the box. Background Technology

[0002] The ladle is a key thermal device in the steelmaking process that carries, transfers, and keeps molten steel warm for ladle refining. The ladle covering agent, directly spread on the surface of the molten steel, is an essential functional material for ensuring steel quality and stabilizing continuous casting production. Its core service requirements include: rapid melting at 1600-1700℃ to form a uniform, sealed slag layer, preventing air absorption and secondary oxidation in the molten steel; low thermal conductivity and high radiation shielding capability to reduce temperature drop in the molten steel and ensure uniform and stable temperature during continuous casting; effective adsorption of non-metallic inclusions such as Al2O3, calcium aluminates, and silicates floating in the molten steel, improving steel cleanliness; and suitable melting temperature and viscosity, preventing crusting, sticking, and corrosion of the ladle lining, while adapting to different refining processes and steel grades. Currently, ladle covering agents face numerous technical bottlenecks: traditional carbonized rice husk covering agents offer good insulation but have high carbon content, easily leading to carbon increase in molten steel and making them unsuitable for high-end steel grades; magnesium-based alkaline covering agents offer high purity and do not increase carbon, but have high raw material costs, slow melting speed, poor spreadability, and are prone to forming a hard shell, resulting in localized exposure of molten steel; while fluorinated fluxing covering agents improve melting performance, high-temperature fluoride volatilization causes severe environmental pollution and equipment corrosion, leading to restrictions on their use by most steel mills. Furthermore, most covering agent products rely on high-temperature pre-melting processes, resulting in high energy consumption, low efficiency, and persistently high production costs.

[0003] The used lithium battery casing is rich in refractory components such as Al2O3, SiO2, and MgO, and also retains a certain amount of Li2O. It is an ideal natural raw material for preparing ladle covering agents. For example, the diffraction pattern of the crushed casing after the synthesis of a certain 6-series cathode material is shown below. Figure 1 As shown, Li2O can simultaneously play multiple roles in high-temperature molten slag, including fluxing, viscosity reduction, slag stabilization, and purification. Its comprehensive performance is superior to that of traditional fluxes. However, current technologies have failed to achieve lithium composition without pre-melting. The efficient utilization of the casing solid waste cannot be converted into a high-performance steel ladle covering agent.

[0004] Therefore, this invention provides a pre-melting-free, low-cost, green, and fluorine-free ladle covering agent preparation technology, which makes full use of the lithium resources in the ladle body to achieve a synergistic breakthrough in the high-temperature performance, heat preservation performance, and purification performance of the covering agent, while also disposing of a large amount of industrial solid waste and promoting the green and low-carbon development of the steelmaking process. Summary of the Invention

[0005] This invention addresses the problems of high energy consumption, fluorine pollution, difficulty in balancing heat preservation and purification, and easy carbon increase associated with traditional ladle covering agents. It provides a method for preparing continuous casting ladle covering agents using used lithium battery casings without high-temperature pre-melting. The method directly uses used lithium battery casings as the main raw material and, through component formulation optimization and in-situ lithium function activation mechanism, prepares a fluorine-free, low-melting-point, high-insulation, highly purified ladle covering agent suitable for high-temperature service.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a continuous casting ladle covering agent using a lithium battery casing includes the following steps: raw material pretreatment, proportioned batching, dry and wet mixing, granulation and molding, curing and drying, and sieving of the finished product, as detailed below: 1) Raw material pretreatment: After the used aluminum-silicon lithium battery casing is manually cleaned, crushed in two stages, and magnetically separated to remove iron, it is then ultra-fine ground to obtain casing powder with a particle size of <74μm. 2) Ingredient composition (percentage by weight, total weight 100%); ; 3) Dry mixing, wet mixing, granulation, curing, drying, and sieving of the finished product; (1) Add the used lithium battery crucible powder, fused magnesia powder, quartz sand powder, lightweight insulation components, dolomite powder, and titanium dioxide to a high-speed mixer according to the proportion, and dry mix at 700~900r / min for 30~50min. (2) Add inorganic binder and deionized water, and wet mix at 450~650r / min for 20~40min to form a uniform plastic mixture; (3) The pellets are formed in a centrifugal granulator, and the particle size is controlled to be 0.3~1.5mm; (4) Dry and solidify in hot air at 130~160℃ for 3~4.5h, and obtain finished ladle covering agent after sieving; Li2O and MgO, Al2O3 and SiO2 generate multi-element low eutectic in situ, which lowers the melting point of the covering agent to 1200~1320℃. It melts and spreads rapidly at the high temperature of the ladle to form a continuous, dense and non-porous high-temperature sealed protective slag layer, which completely isolates the air and prevents the molten steel from absorbing nitrogen and oxygen for secondary oxidation.

[0007] The present invention proposes a method for preparing a continuous casting ladle covering agent using a lithium battery casing. Employing the above-mentioned technical solution, it has the following advantages: 1) Completely eliminates high-temperature pre-melting, simplifying the process, reducing energy consumption, increasing efficiency, and requiring less investment, resulting in significant advantages for industrial applications.

[0008] 2) The utilization rate of the lithium battery casing after use is over 58%, realizing large-scale disposal of solid waste and high-value utilization of lithium resources.

[0009] 3) Fluorine-free, low carbon footprint, and environmentally friendly, solving the pollution and carbon footprint problems of traditional covering agents.

[0010] 4) Rapid slag formation, uniform spreading, long-lasting heat preservation, strong purification, excellent high-temperature stability, and suitable for various steel ladle and refining processes.

[0011] 5) Low raw material cost and stable performance can significantly improve billet quality and reduce overall steelmaking costs.

[0012] 6) High-temperature slag stabilization, corrosion resistance, no crusting, and no slag entrapment: The lithium component can adjust the mineral composition of the slag, generating a stable magnesium aluminum silicate glass phase, improving the high-temperature structural stability of the slag phase, and avoiding slag layer cracking and crusting; at the same time, the viscosity at 1600℃ is precisely controlled at 0.20~0.40Pa・s, which ensures fluidity and avoids slag overturning and slag entrapment, protecting the ladle lining from corrosion; 7) Interface modification for deep purification of inclusions in molten steel: Li⁺ significantly reduces the slag-steel interfacial tension, enhancing the slag's ability to wet, capture, and assimilate inclusions; it also promotes the aggregation and growth of fine inclusions, accelerating their flotation and separation. It exhibits high removal rates for typical inclusions such as Al₂O₃ and calcium aluminates, resulting in a significant improvement in the cleanliness of molten steel. 8) Synergistic insulation to reduce molten steel temperature drop: The refractory components of the box body, the lightweight insulation material and the lithium modified glass slag film form a three-layer insulation structure of "skeleton - porous - dense film", which has low thermal conductivity and strong radiation shielding ability. The molten steel temperature drop rate is ≤1.5℃ / min, which meets the requirements of long-term refining and multi-furnace continuous casting. 9) Fluorine-free and environmentally friendly, does not increase carbon content, and is suitable for high-end steel grades: It completely replaces fluorides with Li2O, with no toxic fumes or fluorine pollution; the carbon content is controllable and does not cause carbon increase in molten steel, and can be used in the production of high-end steel grades such as ultra-low carbon steel, stainless steel, pipeline steel, and automotive steel sheets. Attached Figure Description

[0013] Figure 1 The diffraction pattern is the result of the crushing of the sagger used in the synthesis of a certain 6-series cathode material. Detailed Implementation

[0014] The present invention will be described in detail with reference to the accompanying drawings and specific embodiments: Example 1: Ingredient ratio (mass fraction): 58% box body powder, 16% fused magnesia powder, 10% quartz sand powder, 4% carbonized rice husk, 3% dolomite powder, 2% titanium dioxide, 3% dextrin, and 4% deionized water.

[0015] Process: Dry mix for 30 min, wet mix for 20 min, cure at 130℃ for 4.5 h, particle size 0.3~1.5 mm.

[0016] Properties: Melting point 1255℃, viscosity 0.27 Pa·s at 1600℃.

[0017] Example 2: Ingredient ratio (mass fraction): 72% box body powder, 8% fused magnesia powder, 5% quartz sand powder, 5% carbonized rice husk, 4% dolomite powder, 1% titanium dioxide, 2% pulp, and 5% deionized water.

[0018] Process: Dry mix for 50 min, wet mix for 40 min, cure at 150℃ for 4 h, particle size 0.3~1.5 mm.

[0019] Properties: Melting point 1255℃, viscosity 0.25 Pa·s at 1600℃.

[0020] Example 3: Ingredient ratio (mass fraction): 58.5% for box body powder, 9% for fused magnesia powder, 6% for quartz sand powder, 9% for cenospheres, 6% for dolomite powder, 3% for titanium dioxide, 1.5% for pulp, and 7% for deionized water.

[0021] Process: Dry mix for 40 min, wet mix for 30 min, cure at 160℃ for 3 h, particle size 0.3~1.5 mm.

[0022] Properties: Melting point 1255℃, viscosity 0.21 Pa·s at 1600℃.

Claims

1. A method for preparing a continuous casting ladle covering agent using a lithium battery case, characterized in that: The process includes raw material pretreatment, proportioned batching, dry and wet mixing, granulation and molding, curing and drying, and sieving of the finished product, as detailed below: 1) Raw material pretreatment: After the used aluminum-silicon lithium battery casing is manually cleaned, crushed in two stages, and magnetically separated to remove iron, it is then ultra-fine ground to obtain casing powder with a particle size of <74μm. 2) Ingredients: The ingredients are shown in the table below, by weight percentage, total weight 100%; ； 3) Dry mixing, wet mixing, granulation, curing, drying, and sieving of the finished product; (1) Add the used lithium battery crucible powder, fused magnesia powder, quartz sand powder, lightweight insulation components, dolomite powder, and titanium dioxide to a high-speed mixer according to the proportion, and dry mix at 700~900r / min for 30~50min. (2) Add inorganic binder and deionized water, and wet mix at 450~650r / min for 20~40min to form a uniform plastic mixture; (3) The pellets are formed in a centrifugal granulator, and the particle size is controlled to be 0.3~1.5mm; (4) Dry and solidify in hot air at 130~160℃ for 3~4.5h, and obtain finished ladle covering agent after sieving; Li2O and MgO, Al2O3 and SiO2 generate multi-element low eutectic in situ, which lowers the melting point of the covering agent to 1200~1320℃. It melts and spreads rapidly at the high temperature of the ladle to form a continuous, dense and non-porous high-temperature sealed protective slag layer, which completely isolates the air and prevents the molten steel from absorbing nitrogen and oxygen for secondary oxidation.

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