An Efficient Extraction and Selective of Alumina from Lapindo Mud

Abstract

Lapindo mud, a soft clay soil found in Sidoarjo, East Java, has a high water and mineral content. It contains 16% alumina (Al2O3), making it a potential source of aluminum metal. The high content of silica oxide in Lapindo mud is of particular interest to separate the oxide from the alumina oxide. Silica oxide is insoluble in acid while aluminum oxide is soluble in acid. The alumina extraction process was carried out using acid solvent. The dried mud with a size of ≤100 mesh was extracted using HNO3 and HCl solvent with concentration of 4, 6, and 8 M at temperatures of 60℃, 70℃, and 80℃ for 100, 200, and 300 minutes. The extraction results were filtered, then the pH of the filtrate was adjusted to 12 with 6 M NaOH. The filtrate was filtered, thus Fe3+ was obtained as a residue. The filtrate was neutralized to pH 8 using 6 M HCl. The filtrate was filtered to obtain NaAlO2. The precipitate formed was washed using distilled water and dried in an oven to obtain Al(OH)3. Al(OH)3 was then calcined at 600℃ for four hours to form Al2O3. The results showed that acid solvent concentration, extraction temperature, and heating time affected the mass of Al2O3 obtained. Increasing acid solvent concentration, extraction temperature, and heating time, increases the mass of Al2O3 obtained. The mass of Al2O3 obtained was 1.19 grams for HNO3 solvent and 1.63 grams for HCl solvent with concentration of 8 M, extraction temperature of 80℃, and heating time of 300 minutes. The results of XRF characterization show that the Al3O3 purity level is 42.8% and 27.3%with HNO3 and HCl solvent, respectively.