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本文选用碳含量差别较大的14个煤样,进行激光诱导击穿光谱实验。引入多元校正的分析方法,实现煤中碳元素的LIBS定量分析。根据煤质的结构特点,得到影响碳元素激发的主要影响因素分别为与碳骨架相连的H、O、N,以及主要的矿物质元素Si、Al、Ca、Fe。选择这些元素常见的特征谱线强度值,作为多元回归分析的输入量,然后根据回归方程变量的筛选原则,确定了用于回归关联式建立的变量,进而得到回归关联式,并通过方差分析和回归统计验证了方程的可行性。结果表明,采用多元校正的分析方法,得到多元回归分析模型预测值与实验室元素分析仪得到的参考值之间的相对误差在5%之内,说明采用多变量校正的分析方法对碳元素进行定量分析,能得到较高的分析精度。
In this paper, fourteen coal samples with large difference in carbon content were selected for laser induced breakdown spectroscopy. The multivariate calibration method was introduced to realize the LIBS quantitative analysis of carbon in coal. According to the structural characteristics of coal, the main influencing factors that affect the carbon emission are H, O, N and the major mineral elements Si, Al, Ca and Fe, respectively, which are linked to the carbon skeleton. The intensity values of common spectral lines of these elements are selected as the input variables for multiple regression analysis. Then, the variables used for regression correlation determination are determined according to the screening principle of the regression equation variables, and then the regression correlation is obtained. Regression statistics verify the feasibility of the equation. The results show that using the multivariate calibration method, the relative error between the predicted value of the multiple regression analysis model and the reference value obtained from the laboratory elemental analyzer is within 5%, indicating that the multivariate calibration method is used for the carbon element Quantitative analysis, can get a higher analysis accuracy.