Use of X-ray fluorescence spectroscopy for the determination of rare-earths contained in the concentrates and in landfills from the beneficiation plant of Gakara rare-earth deposit in Burundi

Abstract

The Gakara rare-earth ore deposit in Burundi is the only operating rare-earth mine in Africa and one of the richest rare-earth deposits in  the world with an in-situ content of 47 to 67% rare-earth oxides (REO). However, although the country has significant mineral resources,  Burundi has not yet developed a mining industry and even the Kabezi rare-earth concentration plant only produces concentrates,  exported as such to the raw state, without any added value. Prior to the results of the present study, no quantitative data from  researchers was available on the content of the said concentrate, much less on the nature of the substances that contain it. Therefore,  the present research work focused on quantitative analysis by X-ray fluorescence spectroscopy on rareearth concentrates and on landfills  scattered around the said beneficiation plant. The findings of the present research work reveal that the rare-earth concentrate  from Gakara rare-earth ore deposit in Burundi contains seven metals of this strategic ore including lanthanum (20.5% in elements; 18.0%  in oxides), yttrium (0.16%; 0.15%), cerium (37.75%; 33.75%), praseodymium (2.80%; 2.63%), neodymium (12.14%; 10.00%), samarium  (1.00%; 0.90%) and gadolinium (0.47%; 0.35%). With a total rare-earth elements (TREE) content of 74.84 ± 0.33%, the Gakara rare-earth  concentrate can be refined into seven rare-earth metals. The corresponding total rare-earth oxide (TREO) content is of 65.78 ± 0.29%.  Such findings are highly revealing and constitute a critical step which must lead to an in-depth research on the optimization of a  technological separation and purification process which could be used specifically for this deposit considered as one of the most strategic  globally. Regarding the waste dumps, the present research found that they contain quantities of thorium (0.127%) and lead  (0.237%) at levels that should not be ignored. No uranium was detected.