PURIFICATION OF NICKEL FROM ARTIFICIAL FERRONICKEL LEACH LIQUORS WITH SAPONIFIED CYANEX 272

• Main Author: Suputra Krisnu, Putu
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/85212
• Institution: Institut Teknologi Bandung

The demand for batteries has been increasing rapidly in recent years mainly due to growing electric vehicle (EV) market. Nickel sulfate (NiSO4) and iron phosphate (FePO4) are the main components of the two types of batteries that are widely used today for EVs, namely litium nickel-manganese-cobalt oxide (NMC) and litium iron phosphate (LFP) batteries. Based on previous research, NiSO4 and FePO4 can be obtained from ferronickel (FeNi) through leaching with hydrochloric acid (HCl) and a series of purification processes that include two stages of precipitations, two stages of solvent extraction (SX), and nickel sulfate crystallization. One of the SX stages is to purify Ni, by separating it from its impurities, namely Co, Fe, Mn, and Cr, using bis(2,4,4-trimethyl pentyl) phosphinic acid extractant (Cyanex® 272). In the present study, the separation performance of Ni from Co, Fe, Mn and Cr was studied using Cyanex 272 that was saponified with sodium hydroxide (NaOH). A series of experiments were carried out on a laboratory scale using an artificial solution resulting from a FeNi leaching process that has been treated through a FePO4 precipitation process. Firstly, experiments were performed to separate the remaining Fe from the solution by conducting hydroxide precipitation. Next, SX experiments were performed on Fe-free solutions using saponified Cyanex 272, kerosene as dilution, and tributyl phosphate (TBP) as a phase modifier. In the extraction experiments, the influence of pH, saponification level, extractant concentration, and organic-to-aqueous (O/A) ratio was investigated. Loaded organic obtained in optimum conditions was then used as the feed in the scrubbing experiments by varying the initial pH of the scrubbing agent, i.e. a mildly acidic solution, via a counter-current and cross-current flow. Finally, the stripping experiment was carried out by varying the concentration of the stripping agents (2–4 M HCl). The results of the Fe(OH)3 precipitation experiment showed that the optimum conditions for the selective precipitation of Fe and Cr were obtained at pH 4,2 with the precipitation of Fe and Cr being 100% and 95.82%, with the co-precipitation of Ni, Co, and Mn being 0.34%, 25.66%, 15.45%, respectively. The optimum conditions for the extraction were at the initial pH of 3.5, the saponification level of 10%, the extractant concentration of 10%, and the O/A of 0.8 with Co, Cr, Mn extractions of, respectively, 96.51%, 96.13%, and 100%, and co-extraction of Ni of 1.08%. The results of the scrubbing experiments showed that the scrubbing of Ni from the loaded organic can be performed effectively at pH = 2 and O/A = 1 with the scrubbing of Ni and Co were 94% and 4%, respectively. The optimum stripping conditions were determined to be at HCl concentration of 6 M with stripping percentages of 98.5%, 84.36%, 41.47%, and 100.00% for Ni, Co, Cr, and Mn, respectively. Based on the results of the O/A variation, quantitative Co stripping can be achieved in 2 stages at O / A = 2. The results of the experiments indicate that the saponified Cyanex 272 can separate Ni from its impurities and quantitative scrubbing of Ni from the loaded organic can be achieved.