熔融制样-X射线荧光光谱法测定磷矿石中主次组分

磷矿石是一种不可再生资源,其伴生组分F等也有较高的利用价值,熔片法处理样品后以X射线荧光光谱法(XRF)测定磷矿石中难挥发组分具有精密度高、准确度好的特点,但组分F在高温条件下易挥发,检出限偏高。文章重点研究了F组分高温挥发特性,建立了熔融制样-X射线荧光光谱仪测定磷矿石中P_2O_5、F、SiO_2、Al_2O_3、Fe_2O_3、MgO、CaO、Na_2O、K_2O、TiO_2、MnO和SrO等12种组分的分析测试方法。通过试验确定的分析条件为:稀释比为1∶15,预氧化温度为700℃,熔样温度为1 050℃,熔样时间为4 min。方法中,F、MgO、K_2O为造岩轻组分,无须基体校正;SrO采用Rhα-c作内标;P_2O_5、SiO_2、Al_2O_3、Fe_2O_3、CaO、Na_2O、TiO_2和MnO组分采用理论系数法校正基体效应。方法检出限在0.000 2%~0.042%之间,特别是F组分的检出限可达到0.042%。以GBW07210和GBW07212为对象考察方法精密度,各组分测定结果的相对标准偏差(RSD,n=12)在0.07%~5.1%之间;采用实验方法分析磷矿石标国家标样,及由标准样品合成的样品,测定值与认定值或理论值吻合良好。

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

Phosphate ore is a kind of non-renewable resource, and the associated fluorine also has high value in use. The determination of hardly volatile components in phosphate ore by X-ray fluorescence spectrometry(XRF) after fusion sample preparation has high precision and good accuracy. However, the component fluorine is easily volatilized at high temperature and the detection limit is relatively high. The high temperature volatilization characteristics of fluorine were focused on in the study. The analysis method of 12 components in phosphate ore (including P₂O₅, F, SiO₂, Al₂O₃, Fe₂O₃, MgO, CaO, Na₂O, K₂O, TiO₂, MnO and SrO) by X-ray fluorescence spectrometry with fusion sample preparation was established. The analytical conditions were obtained by experiments: the dilution ratio was 1∶15, the pre-oxidation temperature was 700 °C, the sample fusion temperature was 1 050 ℃, and the fusion time was 4 min. F, MgO and K₂O belonged to rock-forming light components, and the matrix correction was not necessary; Rh_α-c was selected as the internal standard for SrO; the matrix effect on P₂O₅, SiO₂, Al₂O₃, Fe₂O₃, CaO, Na₂O, TiO₂ and MnO was corrected by theoretical coefficient method. The detection limits of method were between 0.000 2% and 0.042%. Particularly, the detection limit of fluorine was 0.042%. The precision of method was investigated using GBW07210 and GBW07212. The relative standard deviations (RSD, n=12) of components were between 0.07% and 5.1%. The national standard sample and synthetic standard samples of phosphate ore were determine according to the experimental method, and the found results were consistent with the certified values of theoretical values.