Optical Spectrum Based Estimation of Grades in Mineral Flotation

Mineral enrichment by notation is one of the hardest industrial processes to monitor and control. The main process measurements collected from a flotation circuit are the metal contents or grades in the different phases of the circuit. To improve the process monitoring capabilities, machine vision systems have previously been developed to characterize the flotation froth properties from digital images of the froth. This study discusses an on-line measurement of the optical froth spectrum in order to improve the slurry grade measurements obtained from the X-ray fluorescence based Courier analyzer. It is shown that the grades of the zinc flotation circuit concentrate can be estimated with a linear multiregression model using the measured froth spectra as input values. The model is then applied to estimate the grades of the concentrate between the originally sparse X-ray fluorescence measurements. Additionally, some preliminary results are presented which suggest that also the spectra measured directly from a slurry flow may correlate with the corresponding grade values.