PURIFICATION OF PREGNANT LEACH SOLUTION OBTAINED BY MIXED HYDROXIDE PRECIPITATE (MHP) LEACHING BY SOLVENT EXTRACTION USING D2EHPA AS EXTRACTANT

• Main Author: Dhita Andriyanto, Visensius
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/75165
• Institution: Institut Teknologi Bandung

Mixed hydroxide precipitate (MHP), which is a product of lateritic nickel ore processing, can be purified into nickel sulfate as a raw material for cathode materials for lithium-ion batteries through a series of leaching processes, purification of leaching solutions by solvent extraction and crystallization. In this research, the process of purifying MHP leaching solution using solvent extraction method using di(2-ethylhexyl) phosphoric acid (D2EHPA) extractant was studied. The MHP used comes from a High Pressure Acid Leaching (HPAL) factory in Indonesia. Series of laboratory experiments were carried out, starting with preparation, characterization, and leaching of MHP samples in 2 M sulfuric acid solution at room temperature and atmospheric pressure for 3 hours, with a slurry density of 100 gram/liter. The nickel-rich solution obtained was then purified by a solvent extraction process using an organic solution consisting of D2EHPA, kerosene, and tri-n-butyl phosphate (TBP) extractants as modifiers. The effect of solvent extraction process variables was studied, namely equilibrium pH, extractant concentration, and volume ratio of organic solution/aqueous solution (O/A). In addition to metal extraction studies, metal scrubbing and metal stripping experiments were also carried out from loaded organic solutions, each with variations in scrubbing agent concentration, O/A ratio, type and pH of the stripping agent solution. The experimental results showed that the percent extraction of Ni, Co, Al, Fe, Zn, Mn, and Mg tended to increase as the equilibrium pH, extractant concentration, and O/A ratio increased. The best extraction conditions were obtained at an equilibrium pH of 3.5, an extractant concentration of 20% (v/v), and an O/A ratio of 1, with a percent extraction of Ni, Co, Al, Fe, Zn, Mn, and Mg respectively of 22 .32%, 29.13%, 100%, 100%, 99.98%, 97.33% and 51.85%. All of the co-extracted Ni and Co can then be scrubbed with sulfuric acid at pH 1.2 with less than 2% co-scrubbing of Al, Fe, Zn, and Mn. Co-scrubbing of Mg was quite high (28.47%) under these conditions because its extraction properties were similar to those of Ni and Co. Percent stripping of Mg, Zn, and Mn can be up to 100% with 0.5 M sulfuric acid solution, but it is difficult for Fe and Al to be completely stripped under a range of experimental conditions in this study. The results of this experiment indicate that the main impurities in MHP, namely Al, Fe, Zn, and Mn can be separated by the solvent extraction method using D2EHPA extractant.