含钙乙酸分离-熔融制样-X射线荧光光谱法测定萤石中氟化钙  

Determination of calcium fluoride in fluorite by X-ray fluorescence spectrometry with fusion sample preparation after separation by calcium-containing acetic acid

作　　者：袁永海[1] 杨锋[1] 吴杰[1] 李博[1] 方贵聪[1] 文美兰[1] YUAN Yonghai;YANG Feng;WU Jie;LI Bo;FANG Guicong;WEN Meilan(Guangxi Key Laboratory of Hidden Metal Mineral Exploration,Guilin University of Technology,Guilin 541006,China)

机构地区：[1]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541006

出　　处：《冶金分析》2023年第3期34-39,共6页Metallurgical Analysis

基　　金：国家重点研发计划(2021YFC2900100);广西研究生创新项目(YCBZ2022119)。

摘　　要：萤石的主要成分为氟化钙,其含量是决定矿石品级的主要指标。采用X射线荧光光谱法(XRF)测定氟化钙时,萤石中的碳酸钙及其他氟化物均会对其产生干扰,从而影响测定结果。采用含钙乙酸(含0.02 mol/L Ca^(2+))溶解萤石,过滤后保留残渣,残渣灰化灼烧至恒重,用质量校正系数法进行酸溶减量校正,以钙谱线为分析谱线,建立了一种XRF测定萤石中氟化钙的方法。实验表明,以四硼酸锂和偏硼酸锂的混合物(m_(四硼酸锂)∶m_(偏硼酸锂)=7∶3)为熔剂,控制熔剂与样品的稀释比为20∶1,以溴化铵溶液为脱模剂,于熔样机上650℃预氧化5 min、1100℃摇动熔融8 min,可制备均匀、透亮的熔片。选用萤石标准物质及人工合成校准样品绘制校准曲线,校准曲线中氟化钙的含量范围为12.17%~94.91%(质量分数,下同),相关系数为0.9998,方法的检出限为0.21%。按照实验方法测定萤石标准物质和实际样品中氟化钙,结果的相对标准偏差(RSD,n=6)均小于1.0%。分别按照实验方法和GB/T 5195.1—2017规定的EDTA滴定法测定8个萤石样品中氟化钙,所得结果相一致。The main component of fluorite is calcium fluoride,and its content is the main index to determine the grade of ore.During the determination of calcium fluoride by X-ray fluorescence spectrometry(XRF),calcium carbonate and other fluorides in fluorite will have interference,thus influencing the determination results.The fluorite sample was dissolved with calcium-containing acetic acid(containing 0.02 mol/L Ca^(2+)).The residue was retained after filtration and then calcined to constant weight.The acid dissolution reduction was corrected by mass correction coefficient method.Consequently,a method for determination of calcium fluoride in fluorite by XRF was established with calcium spectral line as the analytical line.The results showed that the prepared fuse pellet were uniform and transparent under the following conditions:the mixture of lithium tetraborate and lithium metaborate(m_(Li_(2)B_(4)O_(7))∶m_(LiBO_(2))=7∶3)was used as the flux;the dilution ratio of flux to sample was controlled as 20∶1;ammonium bromide solution was selected as the release agent;the sample was pre-oxidized at 650℃for 5 min,and then fused with shaking at 1100℃for 8 min.The certified reference materials of fluorite and artificially synthesized calibration samples were used to prepare the calibration curve with calcium fluoride content in range of 12.17%-94.91%(mass fraction,the same below)and correlation coefficient of 0.9998.The limit of detection of method was 0.21%.The contents of calcium fluoride in certified reference materials and actual samples of fluorite were determined according to the proposed method.The relative standard deviations(RSD,n=6)were all less than 1.0%.The contents of calcium fluoride in eight fluorite samples were determined according to the proposed method and EDTA titration method specified in GB/T 5195.1-2017,and the determination results were consistent.

关 键 词：X射线荧光光谱法(XRF) 萤石 氟化钙 碳酸钙 含钙乙酸 质量校正系数法 EDTA滴定法 

分 类 号：O657.34[理学—分析化学] TF044[理学—化学]