Measurement of alkali content in Zhundong coal by LIBS method

Serious slagging and ash deposition issues occur in combustion of Zhundong coal in industrial power plants due to its high content of alkali (Na, K). In this study, Zhundong coal was treated by chemical methods to make a lot of coal samples with a large range of Na and K concentrations. The results of Inductively Coupled Plasma Spectroscopy (ICP) were used as known variables for the calibration and prediction of Na and K content using laser-induced breakdown spectrum (LIBS).The results showed the measurements of Na and K by LIBS had high sensitivity, low detection limit and low Root Mean Square Prediction Error (RMSEP). The lower element concentration the sample contained, the greater the RSD was. When the element concentration reached a certain value, the RSD of measurement became stable. A large number of repeated measurements can guarantee the accuracy of LIBS measurement. Because LIBS technology itself has the advantage of fast measurement，LIBS could be a valid method to achieve online measurement of alkali content in coal.