Fig. 1. Schematic of the system

Fig. 2. Sample of sinter mixture

Fig. 3. Relationship between mean spectral lines intensity and moisture mass fraction

Fig. 4. Quantitative analysis of four elements. (a) Quantitative analysis diagram of element Fe; (b) quantitative analysis diagram of element Ca; (c) quantitative analysis diagram of element Si; (d) quantitative analysis diagram of element Mg

Fig. 5. Errorbar graphs of predicted mass fraction of four elements before spectral standardization. (a) Errorbar diagram of element Fe predicted mass fraction; (b) errorbar diagram of element Ca predicted mass fraction; (c) errorbar diagram of element Si predicted mass fraction; (d) errorbar diagram of element Mg predicted mass fraction

Fig. 6. RMSE of the predicted each element content corresponding to different sample quantities

Fig. 7. RMSE of predicted each element content corresponding to different number of principal componts

Fig. 8. RMSE of predicted each element content corresponding to different spectral dimensions

Fig. 9. Comparison between standard spectrum and the spectrum with or without standardization. (a) Comparison between standard spectrum and unstandardized spectrum; (b) comparison between standard spectrum and standardized spectrum

Fig. 10. RSD of predicted mass fraction of four elements

Fig. 11. Errorbar graphs of predicted mass fraction of four elements after spectral standardization