Abstract:Niobium was recovered from scandium bearing acid-leaching-residue by fluoride roasting and sulfuric acid leaching. The effects of roasting temperature, roasting time, and dosage of ammonium bifluoride on desilication and niobium enrichment were investigated. The effects of sulfuric acid concentration, dosage of sulfuric acid, leaching temperature, and leaching time on niobium leaching rate were also studied. The results show that desiliconization rate is 95% and niobium concentrate grade in slag is 2.1% under the calcination conditions including temperature of 200 ℃, roasting time of 2.5 h, and mineral salt ratio of 1︰1. 2. Leaching rate of niobium is 80% under the leaching conditions including sulfuric acid concentration of 12 mol/L, leaching time of 2 h, leaching temperature of 80 ℃, and ratio of liquid to solid of 15︰1.