Perpustakaan Digital ITB

Rare earth elements (REEs) nowadays have been such important elements with wide applications in modern technology. In Indonesia, REEs can be found in monazite minerals. Despite the potential, there are still no commercial activities to extract REE in Indonesia. Indonesia has to consider extracting these resources to support the development of modern technologies within the country. The phosphate matrix in monazite minerals, however, has high stability, requiring vigorous conditions to dissolve the REEs from the phosphate bond. This research aims to extract and purify the REEs from Bangka monazite concentrate. In this study, the monazite was decomposed through the sulfuric acid baking technique to break the stable phosphate matrix. The resulting baked product was leached using hot distilled water to dissolve the soluble sulfate compound. The conditions of these experiments follow the optimum parameters found by the previous investigator under comparable experimental conditions. A series of selective precipitation experiments at atmospheric pressure was carried out using the sulfuric liquor to study the effect of some parameters, such as the neutralization agent types, namely MgO, NH4OH, and NaOH, temperature, and pH, on the precipitation performance. The resulting precipitation residue and filtrate were separated through vacuum filtering and analyzed to determine the precipitation percentage of each element. Then, the residue was washed and dried. The dried residue was treated with HCl solution with the variations in pH to leach and separate the co-precipitated REE from impurities-rich precipitate. The results showed that the metal precipitation rate increased with increasing pH from 1.0 to 3.0 with the three neutralization agents. Based on the results, the use of MgO provided the best results for separating REE from the impurities. At pH 1.0, 88.48% total impurities, 40.47% LREE, and 29.24% HREE were precipitated with MgO. Meanwhile, 83.17% total impurities, 64.95% LREE, and 37.54% HREE were precipitated with NH4OH and 75.42% total impurities, 99.51% LREE, and 73.99% HREE were precipitated with NaOH under comparable conditions. The increasing temperature reduced the solubility of REE and increased the solubility of the impurities. The selective leaching experiment at pH 1.0 using precipitate obtained with MgO showed that the leaching percentage increased as the pH value decreased. At pH 1.0, 5.37% LREE, 8.85% HREE, and only 0.27% total impurities were dissolved into the solution.