Research On The Quantitative Analysis Method Of Industrial Powder By Laser Induced Breakdown Spectroscopy

Powder is one of the most common state of raw material during the industrial production.During the industrial process of production,it is often necessary for us to analyze the elemental concentration,like the coal powder in the fire power industry,the cement raw material powder in the cement production,etc.To give helpful evidence and hints for the industrial production process,to further save the resource and energy and protect the environment,there is a demand for one fast and online method for the elements' analyzing.Laser-induced breakdown spectroscopy,LIBS,as a promising chemical analyzing technology,has the advantages of no or simple need for sample preparation,fast analyzing,and potential for long-distance analyzing,low cost and without hazardous radiation.Due to these advantages,LIBS has great potential for industrial powder quantitative analysis.However,the figure of merit for LIBS analysis is hampered greatly by matrix effect from the samples and measurement uncertainty.These two factors make the precision and accuracy of LIBS analysis cannot fulfil the demand of industrial application on a great scale.In this case,our paper will solve this problem both from the data processing method and experimental method.Based on the radiative transfer equation and basic theory of LIBS,we build a onedimensional plasma model.By building and analyzing some results from this model,we discuss on the influence of plasma parameters on the LIBS quantitative analyzing.From the results,we can see the influence of plasma constituents,plasma temperature or electron density,and plasma morphology on the LIBS analyzing process.For the influence of plasma temperature and electron density,we build a modified spectrum standardization model to decrease the influence of the plasma parameter fluctuations.The advantage of this method is directly calibrate the ratio of elemental concentration from their intensity ratios.By applying this method into the analyzing of key elemental ratios of cement raw material powder,we can greatly improve the precision and accuracy of LIBS analysis.In terms of the plasma constituents,to reduce the matrix effect coming from the moisture content in the coal powder during LIBS analysis,based on the results from the relative analysis,we quantify the influence from the moisture and build a dominant-factor model for the improvement of calibration and prediction.Based on our results,this model can efficiently remove the influence of the matrix effect.Furthermore,for the influence of plasma morphology,from the experimental method,to solve the uncertainty problem encountering in the analysis of hazardous aerosols,based on the analysis of the mechanism of uncertainty,we design a bowl-shaped confinement to adjust the position and shape of plasma.The experimental results prove that this method can effectively decrease the measurement uncertainty during the LIBS analysis of aerosol powders.