熔融制样-X射线荧光光谱法测定镍铁冶炼过程物料中10种组分

红土镍矿焙砂、烟尘及电炉渣等镍铁冶炼过程物料经氧化预处理后熔融制样,采用铁矿石、转炉渣标准样品与自制的红土镍矿标样组合建立X射线荧光光谱(XRF)分析校准曲线,实现了镍铁冶炼过程物料中Ni、Fe、SiO₂、MgO、CaO、P₂O₅、Al₂O₃、Cr₂O₃、MnO、Co等10种组分的快速准确测定。试验发现,样品粒度为200目(74 μm),900 ℃温度下空气氧化45 min后,各还原性组分的质量分数均较低,在此氧化条件下经氧化灼烧的红土镍矿焙砂、烟尘及电炉渣样品中金属单质及残碳质量分数均可降至0.1%以下,达到了使用铂黄合金坩埚对样品制备熔融片的要求。选择偏硼酸锂和四硼酸锂混合熔剂、稀释比为10、在1 050 ℃熔融15 min,熔融效果较好。采用理论α系数进行基体校正,各测定组分校准曲线的线性相关系数达到0.999以上。采用红土镍矿及其焙砂、烟尘和电炉渣样品进行分析,精密度实验结果表明,各组分测定值的相对标准偏差(RSD, n=9)小于5%。测定结果根据灼烧减量校正计算后得出样品中各组分含量,结果与化学法测定值基本一致。

Determination of ten components in ferronickel smelting process materials by X-ray fluorescence spectrometry with fusion sample preparation

The ferronickel smelting process materials such as laterite-nickel ore calcine, dust and electric furnace slag were pretreated by oxidization for the fusion sample preparation. The calibration curves for the X-ray fluorescence spectrometry (XRF) analysis were prepared using the certified reference materials of iron ore and converter slag and the self-made standard sample of laterite-nickel ore. The rapid and accurate determination of ten components (Ni, Fe, SiO₂, MgO, CaO, P₂O₅, Al₂O₃, Cr₂O₃, MnO and Co) in ferronickel smelting process materials was realized. It was found that the mass fraction of reducing components was relative low when the sample (200-mesh, 74 μm) was oxidized in air at 900 ℃ for 45 min. Under the tested oxidization conditions, the mass fraction of elementary metals and residual carbon in laterite-nickel ore calcine, dust and electric furnace slag samples could be reduced below 0.1%, which met the requirements of platinum-gold alloy crucible in fusion sample preparation. The fusion results were good when the mixed lithium metaborate and lithium tetraborate was used as the flux, the dilution ratio was 10, and the sample was fused at 1 050 ℃ for 15 min. The matrix effect was corrected by the theoretical α coefficient method. The linear correlation coefficients of calibration curves of components were all higher than 0.999. The laterite-nickel ore and its calcine, dust and electric furnace slag were analyzed by the proposed method. The results of precision test showed that the relative standard deviations (RSD, n=9) was less than 5%. The determination results were corrected according to the loss on ignition to calculate the contents of components in sample. The found results were consistent with those obtained by chemical method.