Enrichment of Tantalum and Niobium Contents in Bangka Tin Slag by NaOH and H₃PO₄Leaching

Abstract

This study explores how 0.23% tantalum and 0.47% niobium in tin slag from the Bangka-Belitung archipelago, Indonesia, are upgraded. To enrich the contents of both metals, this research involves 8M NaOH leaching followed by 0.5M, 1M, and 1.5M phosphoric acid. First, tin slag was roasted at 900°C for 2 hours. Then, the sample was NaOH-leached while H3PO4 was exploited to leach its residues. Next, each of the residues from the leaching processes was characterized by XRF while the filtrates characterization used AAS and ICP-OES. On the one hand, NaOH leaching has proven to decrease the contents of iron, calcium, titanium, and aluminum. On the other hand, 0.5 M H3PO4 leaching optimizes tantalum contents up to 0.85% while 1.0 M H3PO4 leaching maximizes niobium contents up to 1.45%.

Niobium and tantalum recovery from the primary source and from tin slag, an industrial challenge: A review

“…The recovered metal can be reincorporated in the process or used as a raw material for other processes, placing tin slag as a second resource of metals. [ 15 ] Due to the varied compositions of cassiterite natural deposits, Brazilian companies produce Nb and Ta alloys along with tin concentrate production. [ 1 ]…”

“…The alkaline‐acid leaching sequence has already been studied. [ 14,15,30 ] In addiction, sequential leachings, one with water and another with HCl, were used to remove impurities, such as Fe, Mn, Si, Sn, and Ti, from tin slag. [ 20 ]…”

“…Consequently, during tin metal production, Nb and Ta content can be extracted and sent to alloy production, such as FeNb, or even generate a solid material with Nb and Ta with higher concentration, which can be used as feed material for recovery. [ 14,15 ]…”

“…[ 48 ] The occurrence of Nb, Ta, Fe, and titanium (Ti) and their oxides in the slag categorizes it as a secondary resource of these metals. [ 1,13,15 ]…”

“…Nb and Ta recovery could be achieved by mineral processing, such as grinding or gravity separation; by hydrometallurgical processes, such as acid and alkaline leaching; and via pyrometallurgical processes as alkaline roasting. [ 13–15 ]…”