熔融制样-X射线荧光光谱法测定萤石中主次成分

X射线荧光光谱法测定萤石中主次成分,需要解决准确测定氟含量的难题。试验采用无水四硼酸锂和碳酸锂混合熔剂,硝酸钠为氧化剂进行熔融制样,实现了X射线荧光光谱(XRF)对萤石中各组分含量的准确测定。探讨了熔融温度、稀释比、熔融时间等因素对氟含量测定的影响,确定了最佳试验条件。试验表明,当无水四硼酸锂与试样质量比(m_{无水四硼酸锂}:m_试样)为4:1、碳酸钠质量为0.500 0 g、硝酸钠质量为0.500 0 g、熔融温度为980 ℃、熔融时间为8 min时,氟、硫元素的损耗最小,且氟的荧光强度最大。在最佳试验条件下,得到氟化钙、二氧化硅、硫、磷含量测定的线性相关系数均达到0.995以上。对萤石标准样品进行精密度考察,氟化钙、磷、二氧化硅、硫测定结果的相对标准偏差(RSD,n=11)分别为0.31%、3.6%、0.72%、0.92%;采用实验方法测定萤石标准样品和实际样品,其测定值与认定值或湿法值一致,符合常规检测要求。

Determination of major and minor components in fluoriteby X-ray fluorescence spectrometry with fusion sample preparation

During the determination of major and minor components in fluorite by X-ray fluorescence spectrometry (XRF), the accurate determination of fluorine content is a problem that should be solved. The sample was prepared by fusion sample preparation method with sodium nitrate as oxidizing agent and anhydrous lithium tetraborate-lithium carbonate as mixed flux. The accurate determination of each component in fluorite was realized by XRF. The influence of fusion temperature, dilution ratio and fusion time on the determination of fluorine content was investigated to obtain the optimal experimental conditions. The results showed that the loss of fluorine and sulfur was lowest and the fluorescence intensity of fluorine was highest under the following conditions: the mass ratio of anhydrous lithium tetraborate and sample was 4:1; the mass of sodium carbonate and sodium nitrate was 0.500 0 g, respectively; the fusion temperature was 980 ℃; the fusion time was 8 min. Under the optimal experimental conditions, the linear correlation coefficients of calibration curves for calcium fluoride, silicon dioxide, sulfur and phosphorus were all higher than 0.995. The precision test was conducted with certified reference material of fluorite. The relative standard deviation (RSD, n=11) of calcium fluoride, phosphorus, silicon dioxide and sulfur was 0.31%, 3.6%, 0.72% and 0.92%, respectively. The experimental method was applied to the determination of certified reference material and actual sample of fluorite. The results were consistent with the certified values or those obtained by wet method. The proposed method could meet the requirements of routine testing.