磷酸蒸馏–化学分析法测定冶金用化渣剂中氟含量的方法建立与验证

Establishment and Validation of a Phosphoric Acid Distillation-Chemical Analysis Method for Determining Fluorine Content in Metallurgical Slagging Agents

摘要: 冶金用化渣剂基体复杂，现有氟蒸馏容量法存在温控窗口窄、高氯酸–磷酸混合酸安全隐患突出、氯离子干扰严重等问题。基于此，本研究建立了一种以纯磷酸替代高氯酸–磷酸混合酸测定化渣剂中氟含量的分析方法，并进行了系统的方法学验证。采用纯磷酸消解样品，将蒸馏温控区间拓宽至130℃~180℃，从源头规避了爆炸风险与氯气干扰；针对磷酸挥发对酸碱滴定的正偏差干扰，引入乙酸钠缓冲掩蔽法予以消除。在最佳实验条件下(磷酸用量15 mL、蒸馏温度130℃~180℃、馏出液体积110 mL)，对高、中、低三种氟含量梯度的化渣剂样品进行6次平行测定，相对标准偏差(RSD)为0.39%~0.65%，标准物质测定值与认定值高度吻合(相对误差 ≤ ±0.03%)，加标回收率为96.2%~103.4%。实验结果表明，本方法精密度优良、准确度可靠、操作稳定可控，实现了对经典氟蒸馏容量法的重大安全性与抗干扰改进，可为复杂冶金辅料中氟含量的精准检测提供技术支撑。

Abstract: The matrix of metallurgical slagging agents is complex, and the existing fluoride distillation-volumetric method suffers from problems such as a narrow temperature control window, prominent safety hazards associated with perchloric acid-phosphoric acid mixed acid, and severe chloride ion interference. Based on this, this study established an analytical method for determining fluorine content in slagging agents by replacing the perchloric acid-phosphoric acid mixed acid with pure phosphoric acid, and conducted systematic methodological validation. Using pure phosphoric acid for sample digestion, the distillation temperature control range was broadened to 130˚C~180˚C, thereby fundamentally avoiding explosion risks and chlorine gas interference. To address the positive deviation interference caused by phosphoric acid volatilization on acid-base titration, a sodium acetate buffer masking method was introduced for elimination. Under the optimal experimental conditions (phosphoric acid dosage of 15 mL, distillation temperature of 130˚C~180˚C, distillate volume of 110 mL), six parallel determinations were performed on slagging agent samples with high, medium, and low fluorine content gradients. The relative standard deviations (RSD) ranged from 0.39% to 0.65%. The measured values of certified reference materials were in excellent agreement with the certified values (relative error ≤ ±0.03%), and the spiking recoveries ranged from 96.2% to 103.4%. The experimental results demonstrate that this method exhibits excellent precision, reliable accuracy, and stable and controllable operation, achieving significant improvements in both safety and anti-interference performance over the classical fluoride distillation-volumetric method. It can provide technical support for the accurate determination of fluorine content in complex metallurgical auxiliary materials.