Fractional Precipitation of Rare-Earth Metals and Manganese from Hydrochloric Acid Solutions by Ammonium Carbonate

The possibility of using the fractional precipitation of rare-earth metals (REMs) and manganese from hydrochloric acid solutions by ammonium carbonate is considered. Specific features of the behavior of elements during precipitation, which are necessary to know when preparing selective REM and manganese concentrates, have been revealed. At pH 5.25, 85% ΣTR₂O₃ pass to a deposit (in the oxide formula, ΣTR is the commonly accepted international designation of REMs), and the REM content is 60.5%. At pH 5.25–7.4, 92% manganese are extracted to a manganese concentrate, and the MnO content in the concentrate reaches 70.7%. The complicated chemical composition of the solution requires three-stage fractional precipitation for preparing qualitative selective concentrates: iron and thorium should be precipitated as a cake at the first stage, and REMs and manganese should be precipitated at the second and third stages, respectively. This makes it possible to form deactivated concentrates in the form of carbonates suitable for the further extraction of REMs and manganese by the well-known methods.