Effects of atom substitutions and dissolved carbonate species on monazite electrophoretic mobility

Abstract

In this study, the atom substitutions that commonly affect the monazite lattice were considered as potential factors affecting the monazite electrophoretic mobility. The influence of light rare earth elements (LREE) substitutions and the presence of thorium, calcium, and silicate within the monazite crystal lattice was also examined using a natural monazite and synthetic cerium, lanthanum and neodymium monazite materials. Electrophoretic mobility measurements performed after treatment in an electrolyte solution equilibrated with air outline that LREE substitutions and other substitutions observed in the tested natural monazite did not affect the mineral surface properties.Conversely, the electrophoretic mobility of the synthetic monazites was found to be significantly affected by the amount of dissolved carbonate species present in the aqueous media. More precisely, carbonate species were found to decrease the electrophoretic mobility of monazite. Unlike tests performed with a solution equilibrated with air, the electrophoretic mobility of monazite treated in a CO2 depleted electrolyte solution, under controlled atmosphere, were found erratic. This highlights the difficulty in obtaining reliable electrophoretic mobility data when the carbonate content in the supporting electrolyte solutions is not controlled.