EVALUATION OF THE EFFECTIVENESS OF PRECIPITATION METHODS FOR THE SEPARATION OF RARE EARTH ELEMENTS (REES) FROM MINE WATERS

ABSTRACT

The article presents the results of investigations into the effectiveness of precipitating rare earth elements (REEs) from mine waters using solutions of alkalinizing reagents (NaOH, Ca(OH)2, Na2CO3), sulphur-containing compounds (sodium trithiocarbonate, sodium trimercapto-s-triazine, sodium dimethyldithiocarbamate) and oxalic acid. The investigations were conducted in two stages. In the first stage, based on initial tests, after REEs precipitation, a compound selected from the alkalinizing reagents group (NaOH) was used, taking into account its efficacy, the amount of sediments formed and their physico-chemical properties, beneficial from the point of view of further treatment. In the second stage the sediments precipitated with NaOH were digested in a mixture of acids and REEs were selectively precipitated with oxalic acid. The efficiency of the investigated process was thoroughly evaluated, taking into consideration the initial concentration of REEs in the mine water used in research and the final concentration of REEs in the obtained sediment, after using oxalic acid as a selective precipitating reagent. The research results confirmed the possibility of obtaining initial REEs concentrates from AMD in the precipitation process using selected reagents. The effectiveness of REEs recovery from selected AMDs achieved as a result of the conducted works was more than 95%.

Keywords: Rare Earth Elements, REEs, chemical precipitation, separation, mine waters.