Recovery of Tin, and the Production of Niobium Pentoxide and Potassium Tantalum Fluoride from a Tin Slag

摘要

The report describes the results of testwork on the recovery of tin, niobium, and tantalum from a tin slag. The slag, which consisted mainly of amorphous silica with varying amounts of calcium, magnesium, manganese, iron, and aluminum, contained an average of 8.8 percent niobium pentoxide and 6.2 percent tantalum pentoxide. The metallic tin-iron phase was removed from the crushed slag by magnetic separation. The slag was then leached. The upgraded concentrate thus obtained was purified. Niobium pentoxide and potassium tantalum fluoride were then precipitated by the addition of ammonium hydroxide and potassium fluoride to the strip liquors. The overall recoveries in the upgraded concentrate were 98 percent for tantalum and 92 percent for niobium. Dissolutions and recoveries of over 99 percent were obtained for both tantalum and niobium in the purification steps. The niobium pentoxide and potassium tantalum fluoride precipitates obtained were of high purity.