粉末压片制样-波长色散X射线荧光光谱法测定直接还原铁中6种组分

直接还原铁中的Si、Al、P、Mg、Ca和S等杂质元素对钢的质量有重要影响,目前一般采用化学湿法分析和熔融制样-X射线荧光光谱法检测,程序相对繁琐。为缩短检测周期,研究采用粉末压片制样-X射线荧光光谱法测定直接还原铁中SiO₂、Al₂O₃、P、MgO、CaO和S,通过试验确定将淀粉作为粘结剂,在7.000 0 g样品中加入0.350 0 g淀粉,研磨120 s混匀并使其粒度小于0.074 mm,于30 t压力下压制成片。选取与待测试样组成、结构及粒度相似的具有一定梯度含量的直接还原铁标准样品/校准样品建立校准曲线,SiO₂、Al₂O₃、P、MgO、CaO和S校准曲线的线性相关系数分别为0.999、0.998、0.992、0.995、0.997和0.999。按照实验方法测定直接还原铁中SiO₂、Al₂O₃、P、MgO、CaO和S,结果的相对标准偏差(RSD,n=11)分别为0.014%、0.030%、0.076%、0.009%、0.026%和0.047%;分别采用实验方法与国家标准方法测定直接还原铁中SiO₂、Al₂O₃、P、MgO、CaO和S,结果相一致。方法满足进口直接还原铁样品的快速检测要求。

Determination of six components in direct reduced iron by X-ray fluorescence spectrometry with pressed powder pellet

The impurity elements such as silicon, aluminum, phosphorus, magnesium, calcium, and sulfur in direct reduced iron have an important impact on the quality of steel. At present, these elements are usually determined by chemical wet analysis or X-ray fluorescence spectrometry(XRF) with fusion sample preparation. However, the measurement procedures of the method above are relatively complicated. To shorten the detection time, the method for the determination of SiO₂, Al₂O₃, P, MgO, CaO and S in direct reduced iron by X-ray fluorescence spectrometry with pressed powder pellet was studied. The starch was selected as the binder in experiments. 0.350 0 g of starch was added into 7.000 0 g of sample. The mixture was ground for 120 s to reduce the particle size less than 0.074 mm. Then the pellets were prepared under pressure of 30 t. A series of direct reduced iron standard sample/calibration sample with certain content gradient, which had similar composition, structure, and particle size to the testing samples, were selected as the calibration samples to establish the calibration curves. The linear correlation coefficients were 0.999, 0.998, 0.992, 0.995, 0.997 and 0.999 for SiO₂, Al₂O₃, P, MgO, CaO and S, respectively. The contents of SiO₂, Al₂O₃, P, MgO, CaO and S in direct reduced iron were determined according to the experimental method. The relative standard deviation (RSD, n=11) for SiO₂, Al₂O₃, P, MgO, CaO and S was 0.014%, 0.030%, 0.076%, 0.009%, 0.026% and 0.047%, respectively. The proposed method and national standard method were used to determine the contents of SiO₂, Al₂O₃, P, MgO, CaO and S in direct reduced iron, and the results were consistent. The proposed method could meet the requirements of rapid detection of imported direct reduced iron samples.