Application of Raman spectroscopy to the flotation process of fluorite

Abstract

Exact knowledge of the content of the various components in a flotation system is critical in both product analysis and process control. In the present work, FT Raman spectroscopy was successfully applied to an industrial fluorite flotation system for quantification of calcium fluoride (CaF2). In a first step, an artificial model system consisting of CaF2, barium sulphate and silica was set up to test feasibility of FT Raman spectroscopy and to generate a calibration curve. An empirical model was developed, which incorporates effects of particle size on Raman shift and peak area, so that a CaF2 quantification is feasible independent of particle size. Conversely, the empirical model provides information about the approximate particle size in the analysed sample. A cross-validation using X-ray fluorescence spectroscopy showed excellent quantification of CaF2 in seven industrial fluorite samples with CaF2 weight fraction in a range from 7% to 98% with absolute differences of less than 5%. In a first laboratory batch-flotation experiment, the CaF2 content of the froth product could be quantified successfully providing additional information about the approximate median particle size of the concentrate, making FT Raman spectroscopy superior to commonly applied X-ray fluorescence spectroscopy.