熔融制样波长色散X射线荧光光谱法测定白云石中钙镁硅铁铝

Determination of Calcium,Magnesium,Silicon,Iron and Aluminum in Dolomite by Wavelength Dispersive X-ray Fluorescence Spectrometry with Fusion Sample Preparation

白云石属碳酸盐矿物,应用熔融制样X射线荧光光谱法测定其中主次量组分钙、镁、硅、铁、铝时,由于白云石灼烧减量大,在试料片制备过程中,如果以干基试料制备试料片,除灼烧减量外还有少量其他组分被分解出的大量CO2带走,导致试料损失,测定结果偏低;如果以灼烧基试料制备试料片,由于灼烧后的试料极易吸收空气中的水分和CO2,同样使测定结果偏低。基于质量守恒原理,本文直接以灼烧减量测量后的灼烧基试料质量作为试料量（即灼烧减量测定所称量的干基试料量扣除灼烧减量的量）,以四硼酸锂为熔剂,5%碘化铵溶液为脱模剂,试料与熔剂的稀释比为1∶10,于1050℃熔融15 min以上制备的试料片透彻、玻璃化程度高。以白云石标准物质和标准样品作为标准试料,制作各组分的标准曲线的相关系数在0.9940-0.9994之间;方法检出限为0.011%-0.48%;标准物质和标准样品的测定值与认定值基本一致,各组分的相对标准偏差（RSD,n=11）在0.5%-1.7%之间,方法具有较好的重现性。本方法以1050℃灼烧后的试样作为试料制备XRF分析样片,最大限度地降低了灼烧减量因素（空气中的水分和CO2）对测定结果的影响,适用于白云石及其煅烧物中钙、镁、硅、铁、铝等组分的同时测定。

A method has been developed for the determination of calcium,magnesium,silica,iron and aluminum in dolomite by Wavelength Dispersive X-ray Fluorescence Spectrometry. Dolomite is a carbonate mineral with a large portion of loss on ignition. In the process of test glass disc preparation,if dry-base sample powder is used,a small amount of test components evaporates with the large amount of carbon dioxide,and causes lower determination results; if the ignited test portion is used,because of moisture and carbon dioxide in air being easily absorbed by the ignited sample powder,the determination results are also be low. To avoid these influences,the mass of the ignited test portion was directly used as the amount of test portion,and fused under 1050℃ with fusion agent lithium tetraborate for glass disc preparation. 5% ammonium iodide solution was used as the releasing agent,and the dilution proportion of test portion and fusion agent was 1 ∶ 10. Dolomite reference standard materials and samples were used for calibration. The related coefficients of all components were in the range of 0. 9940- 0. 9994,and the limits of detection were in the range of 0. 011%- 0. 48%. Accuracy and repeatability of the proposed method were good,the results of determination were in good agreement with certified values and the relative standard deviation（ RSD,n = 11） was in the range of 0. 5%- 1. 7%. This method is suitable for simultaneous determination of calcium,magnesium,silica,iron and aluminum in dolomite and its ignited residues.