SCANDIUM EXTRACTION THROUGH RE-LEACHING OF THE PRESIPITATE FROM THE SOLUTION PURIFICATION PROCESS OF HALMAHERA LATERITE NICKEL ORE LEACHING AT HIGH TEMPERATURE AND PRESSURE

• Main Author: Najah, Rofingatun
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/56274
• Institution: Institut Teknologi Bandung

Scandium is one of the rare earth metals that has been widely developed as an alloying element for aluminum, solid electrolytes in solid oxide fuel cells (SOFCs), and several other modern world applications. Its rare existence and high production costs cause the price of scandium is still very expensive. One of the primary sources of scandium is nickel laterite ore which is reported to have Sc contents in the range of 50-60 ppm. The process of extracting scandium from laterite nickel ore, especially limonite ore is still being studied. Previously, research on the leaching of scandium from Halmahera limonite ore has been carried out using the High Pressure Acid Leaching (HPAL) process in sulfuric acid solution. In this study, a purification process for the HPAL solution was carried out which included two-stage iron precipitation and scandium re-leaching from stage II iron precipitates. This study aimed to study the behavior of twostage iron precipitation and scandium re-leaching of stage II iron precipitates. The leaching of nickel laterite ore from Halmahera Island was carried out in a sulfuric acid solution to obtain a pregnant leach solution containing scandium, nickel, cobalt and some metal impurities. The next step was two-stage iron precipitation with Ca(OH)2 as neutralizing reagent at constant pH, temperature and time conditions. In the second stage of iron precipitation process, scandiumrich precipitates were produced which are then re-leached. A series of scandium re-leaching experiments of stage II iron precipitates in sulfuric acid solution were carried out to study the effect of leaching time, temperature, acid concentration, and solid-liquid ratio on the extraction percentages of scandium, nickel, cobalt, iron, and aluminum which were considered as metal impurities of the scandium product. The concentrations of dissolved scandium, nickel, cobalt, iron, and aluminum were analyzed using Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). The experimental results showed that in the first stage of iron precipitation at pH 2.75, Fe precipitation was 72.19% with the precipitation of Sc, Ni, Co, and Al of 4.00%, 0.88%, 0.95%, and 4.03%, respectively. Meanwhile, in stage II iron precipitation at pH 4.75, Fe precipitation was 88.32% with Sc, Ni, Co, and Al precipitations of 99.81%, 42.88%, 36.66%, and 99.88%, respectively. The best conditions for Sc re-leaching were obtained at leaching of 90 minutes, temperature 35oC, H2SO4 concentration 100 g/L, and solid-liquid ratio 0.2 g/mL with 98.61% Sc extraction and co-extraction of Ni, Co, Fe, and Al 83.75%, 93.93%, 81.29%, and 91.64%, respectively. The process of purification of the HPAL solution through 2 stages of iron precipitation can increase Sc levels from 72 ppm in the ore to 241 ppm in precipitate from stage II precipitation.