Fig. 1. Schematic diagram of the experimental setup

Fig. 2. Typical spectra of Lithium ore

Fig. 3. The RMSECV of the PLSR calibration model varying with the number of PCs

Fig. 4. PLSR prediction model

Fig. 5. The explained variance ratio changes with PCA principal component number

Fig. 6. Loadings plots of the first two principal components

Fig. 7. Variation of RMSECV with regularization parameter C of SVR

Fig. 8. PCA+SVR prediction model