Perpustakaan Digital ITB

The term rare earth elements (REE) represents the group of 17 chemically similar metallic elements that consist of lanthanides with the addition of scandium (Sc) and yttrium (Y). REE are used in many advanced technologies. One of the most utilized minerals as REE resources is monazite (REPO4). In Indonesia, an appreciable amount of monazite is available in Bangka Island as a byproduct of tin ore processing. There are several studies about monazite processing, but only limited information is available regarding the processing of Bangka monazite. Hence, this study aimed to investigate the processing of Bangka monazite ore to extract REE. The sulfuric acid baking technique was used as it is currently the most common commercial technology to process monazite. A series of acid-baking experiments were carried out to investigate the effect of sulfuric acid-concentrate ratio, baking temperature, and baking time on the extraction of REE, thorium (Th), and uranium (U). The experiment was performed by combining monazite ore (particle size <75 ?m) with concentrated sulfuric acid in a glazed porcelain crucible followed by baking in a muffle furnace. The baked monazite was then subjected to water leaching at 70 ºC using a three-neck flask on a hot plate equipped with a magnetic stirrer. The experimental results showed that the extraction of REE, Th, and U increased with an increasing acid-concentrate ratio. The highest extractions of REE (95.7%), Th (100%), and U (100%) were all achieved at the ratio of 3:1 with 200 ºC baking temperature. Generally, the extraction of REE, Th, and U decreased as the temperature increased in the range of 300–500 °C. Meanwhile, the extraction of Th decreased sharply from 72.46% at 300 °C, to 0.84% and 0.43%, at 400 dan 500 °C, respectively. Furthermore, the REE extraction was also found to decrease from 74.54% at 300 °C, respectively to 57,79% and 53,88% at 400 and 500 °C due to the formation of REE polyphosphate. The effect of baking time on the extraction was found to be minor at the range of 1–2 hours, but notable changes were observed at 2?3 hours of baking. The best parameter to digest Bangka monazite using the sulfuric acid baking technique was found to be at the acid-concentrate ratio of 3:1, the temperature of 200 °C, and 3 hours of baking