高品质低碳钢板坯连铸保护渣降Li<sub>2</sub>O的探索

doi:10.13228/j.boyuan.issn0449-749x.20230159

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摘要 Li₂O能有效改善连铸保护渣的熔化和流动性能,常用于高品质低碳钢板坯连铸保护渣的重要助熔剂。然而,近两年受下游需求强劲的影响,碳酸锂价格持续走高,增加了连铸坯生产成本。首先开展实验室研究,重点讨论了不同碱度下Li₂O对保护渣黏度和熔化温度的影响;然后分阶段开展了4轮工业试验,试验评价效果包括,结晶器铜板热电偶温度和摩擦力曲线,吨钢渣耗量和铸坯表面质量。实验室研究结果表明,当碱度为0.65~1.25时,随着Li₂O含量的增加,保护渣的熔点和黏度均呈现出降低的趋势,且黏度降低的幅度较明显。为了保证连铸顺行以及低碳钢铸坯表面质量,降低Li₂O的同时需要调整渣中Al₂O₃、Na₂O和F^-的含量,以达到协调熔渣的熔化和流动性能以及吸收Al₂O₃夹杂后性能的稳定性。优化渣的碱度为0.98、黏度为0.26 Pa·s、熔点为1 130 ℃,均在低碳钢保护渣性能要求范围内。原保护渣与优化渣相比,Li₂O质量分数大幅降低,由3.79%降低至0.79%,Na₂O质量分数由1.57%提高到6.54%,Al₂O₃质量分数由12.05%降低至3.62%。优化渣在使用前后,黏温曲线中所呈现出的高温阶段(1 200～1 300 ℃)的黏度基本重合,转折温度有所提高。优化渣浇铸效果稳定,结晶器热电偶温度和摩擦力曲线波动平稳,铸坯和轧材无保护渣类缺陷。从保护渣方面降低连铸生产成本,研究成果具有一定的借鉴和推广价值。

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	吴萧萧
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关键词 ： Li₂O, 板坯, 连铸, 保护渣, 理化性能

Abstract：Li₂O can effectively improve the melting and flow properties of continuous casting mold fluxes, and is commonly used as an important constituent in mold flues in high-quality low-carbon steel slab continuous casting. However, in the past two years, due to strong downstream demand, the price of lithium carbonate has continued to rise, leading to the increased production cost of continuous casting. Firstly, laboratory research was carried out, focusing on the influence of Li₂O on the viscosity and melting temperature with different basicity; Then four industrial tests were carried out in stages, and the evaluation indicators included the curves of the mold copper plate thermocouple temperature and friction force, the consumption of steel slag per ton, and the surface quality of the strand. The results show that in the range of bascity from 0.65 to 1.25, with the increase of Li₂O content, both the melting point and viscosity show a downward trend, and the viscosity decreases significantly. In order to ensure smooth continuous casting and strand surface quality, it is necessary to adjust the content of Al₂O₃, Na₂O, and F^- in the fluxes while decreasing Li₂O, in order to achieve coordination of the melting and flowing properties of the fluxes and stability of the performance after absorbing Al₂O₃.The basicity of the optimized slag is 0.98, the viscosity is 0.26 Pa·s, and the melting point is 1 130 ℃, all of which are within the performance requirements of low-carbon steel mold flux. Compared with the optimized flux, the mass percent of Li₂O of the original mold flux was significantly decreased from 3.79% to 0.79%, and the mass percent of Na₂O was increased from 1.57% to 6.54%, the mass percent Al₂O₃ was decreased from 12.05% to 3.62%. Before and after use, the viscosity of the optimized slag in the high-temperature stage (1 200-1 300 ℃) shown in the viscosity- temperature curve basically coincides, and the transition temperature has increased. The operation of optimized flux is stable, the curves of the mold copper plate thermocouple temperature and friction force fluctuate smoothly, and the continuous casting strand and rolled sheet are free of defects related with mold fluxes. This study aims to reduce the production cost of continuous casting from the perspective of mold fluxes, and the research results have certain reference and promotion value.

Key words： Li₂O slab continuous casting mold flux physical and chemical property

收稿日期: 2023-03-30

引用本文:

吴萧萧, 习在辉, 何生平, 王强强, 张旭彬. 高品质低碳钢板坯连铸保护渣降Li₂O的探索[J]. 钢铁, 2023, 58(8): 110-119. WU Xiaoxiao, XI Zaihui, HE Shengping, WANG Qiangqiang, ZHANG Xubin. Exploration of Li₂O reduction by mold flux for high quality low carbon steel slab continuous casting[J]. Iron and Steel, 2023, 58(8): 110-119.

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