熔融制样-X射线荧光光谱法测定轻烧白云石中主要成分

熔融制样-X射线荧光光谱法(XRF)测定轻烧白云石样品,需重点解决无标准样品的难题。由于轻烧白云石是由白云石原料在1000℃煅烧而成,因此采用具有含量梯度的系列煅烧后的白云石有证标准样品绘制校准曲线,各待测元素校准曲线的线性最大偏离小于0.4%,有效解决了缺少白云石标准样品的问题。轻烧白云石样品以Li₂B₄O₇为助熔剂,采用高温熔融制样,实现了熔融制样-X射线荧光光谱法对轻烧白云石中SiO₂、CaO、MgO含量的测定。对熔融制样条件进行优化,确定试样与熔剂以1:13的稀释比,以3滴500g/L NH₄Br溶液为脱模剂,在1100℃熔融15min,熔融制得的玻璃熔片均匀、透明、无气泡,符合测定要求。方法应用于轻烧白云石实际样品中SiO₂、CaO和MgO的测定,结果的相对标准偏差(RSD,n=10)在0.22%~1.4%之间;正确度试验表明,轻烧白云石样品的测定结果与国家标准方法GB/T 3286.1—2012和GB/T 3286.2—2012测定结果相符。

Determination of main components in light-burned dolomite by X-ray fluorescence spectrometry with fusion sample preparation

For the determination of light-burned dolomite samples by X-ray fluorescence spectrometry (XRF) with fusion sample preparation, the problem that there is no standard sample should be focused on. Since the light-burned dolomite was prepared by burning dolomite raw material at 1000℃, a series of certified reference material of burned dolomite with content gradient were employed to draw the calibration curve. The linear maximum derivations of calibration curves of elements were all less than 0.4%. It effectively solved the problem of lack in standard sample for dolomite. The light-burned dolomite sample was prepared by fusion at high temperature using Li₂B₄O₇ as the flux. The determination method of SiO₂, CaO and MgO in light-burned dolomite by X-ray fluorescence spectrometry (XRF) with fusion sample preparation was established. The fusion sample preparation conditions were optimized: the dilution ratio between sample and flux was 1:13; three drops of 500g/L NH₄Br solution were used as release reagent; the mixture was fused at 1100℃ for 15min. The fused glass sheet produced was uniform, transparent and free of air bubbles, which could meet the determination requirements. The proposed method was applied for the determination of SiO₂, CaO and MgO in actual light-burned dolomite samples. The relative standard deviations (RSD, n=10) of the results were between 0.22% and 1.4%. The trueness test results indicated that the determination results of light-burned dolomite samples were consistent with those obtained by national standard methods, i.e., GB/T 3286.1-2012 and GB/T 3286.2-2012.