Enrichment on Bangka tin slag's tantalum and niobium oxide contents through non-fluoride process

This research explored how non-fluoride solutions including 8M NaOH, 0.8, 1.6 and 2.4 M H ₂ SO ₄ , and 0.1, 0.4 and 0.8 M HClO4 increased the contents of tantalum and niobium oxide through leaching. Before leaching, Bangka tin slag (BTS) was characterized through XRF. The slag was then 900°C-roasted, quenched, and dewatered. Next, BTS underwent a sieving process with size classifications of +100, -100+150, -150+200, -200+250, and -250 mesh. After that, the -200+250 mesh slag was leached with 8M NaOH. Then, the leached product was divided into two, one of which was 0.1, 0.4, and 0.8 M HClO4-leached and the rest of which was leached with 0.8 M HClO ₄ followed by 0, 0.8, 1.6, and 2.4 M H ₂ SO ₄ at 25°C within 2 hours. All the residues characterization used an XRF while that of filtrates used an AAS as well as an ICP-OES. The motives that drive this investigation are the deficit of tantalum supply and its status as one of the technology-critical elements. In addition to that, most of prior investigations enhanced the contents of tantalum and niobium oxide using fluoride acid while this study ventured non-fluoride solutions. The result shows that perchlorate acid followed by sulfuric acid leaching slightly enriches the tantalum and niobium contents. However, this method is the most effective among NaOH, HCIO ₄ , and HCIO ₄ followed by H ₂ SO ₄ leaching. This finding is a form of scientific effort to maintain the tantalum supply through utilizing worthless waste of tin smelting.