Extraction and Enrichment of Lanthanide from Indonesian Low Grade Bauxite using Sulfuric Acid Heap Leaching and Phytic Acid

Abstract

The Indonesian low grade bauxite from Wacopek, Bintan Island is of high economic value because it has 0.0052% lanthanum oxide (La₂O₃) and 0.0052% yttrium oxide (Y₂O₃). In this study, the lanthanides (La and Y) have been successfully extracted from the low grade bauxite using heap leaching method with sulfuric acid, precipitated with trisodium phosphate and complexing with phytic acid (PA). The optimal concentration of 0.1 M sulfuric acid 500 mL, 20 g bauxite could dissolve 24.39% lanthanum and 34.03% yttrium. After the extraction process using H₂SO₄, the extraction was followed by the precipitation reaction using trisodium phosphate (TSP). Phytic acid ligand has proven to precipitate some impurities such as Al, Fe and Mg ions. Here, PA has successfully removed 57.125% of Fe³⁺ impurities in pregnant leach solution (PLS). After two times precipitation and complexing methods using TSP and PA, concentration of lanthanum and yttrium increased to 83.6% (0.04411 ppm) and 89.20% (0.28431 ppm), respectively. The phosphate groups of PA as active sites is favorable selective to bind with heavy metal ions. Based on these results, PA is used to precipitate the impurities and formed complexes, thus PA was expected to have high effectiveness for lanthanide enrichment. Finally, this complexing process with PA have succeeded enrichment of lanthanum to 83.6% (0.04411 ppm) and yttrium up to 89.20% (0.28431 ppm).