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Solids Composition Measurements of Phosphate Slurry Using Impedance Spectroscopy. Phase I: Feasibility Study


The accurate online concentration measurement of solid constituents within a slurry mixture entering a phosphate beneficiation plant can assist to significantly improve the phosphate flotation efficiency. This report includes an impedance spectroscopy feasibility study for the online determination of solid constituent concentrations flowing in a slurry pipeline. A bench scale slurry flow facility has been fabricated, and the test section has been configured with various electrode combinations. An Agilent 4294A impedance spectrometer is used to measure the impedance characteristics of a flowing slurry consisting of water, sand, and amine concentrate over a wide range of frequency. It has been observed that signal quality obtained from the spectrometer is largely dependent on the electrode surface area to spacing ratio. Mathematical algorithms have been developed to measure the amine, sand, and water concentrations from the impedance spectrometer signal, provided the impedance characteristics of the water are known a priori. Also, an algorithm was developed to distinguish the total solids concentration from that of the water, without having to know the impedance characteristics of the water a priori. Thus, it is concluded that with further effort, it should be possible to construct an impedance based instrument to measure the online concentration of water, amine, and sand constituents from a phosphate slurry flowing through a pipeline.