Application of near infrared spectroscopy to rapid analysis of coals

Comparing near infrared (NIR) spectra with infrared spectra in case of coal samples, we generally notice NIR spectra have less characteristic absorbance bands. However, utilizing merits of NIR spectroscopy (non destructive, high penetration ability, simple sample preparation, rapid analysis) and partial least squares regression (PLS) model, we found that several major properties of coals could be conveniently and rapidly estimated. For examples, multiple correlation coefficient between the measured values vs. the predicted values from obtained spectra, R-2, of moisture, volatile matter, oxygen content, maximum fluidity temperature, solidification temperature were 0.9736, 0.9774, 0.8996, 0.8849 and 0.9282 in respectively although the precision of obtained results were not superior to those by methods of American Standard of Testing Materials.