A novel approach to extract Nb, Y and Ce from a niobium-bearing ore of low grade by roasting KHSO4–H2SO4 system

Abstract

In this work, a novel approach of leaching valuable metals, such as niobium, yttrium and cerium, from a niobium-bearing ore of low grade by roasting KHSO4–H2SO4 system was experimentally studied. Through the work, the effects of roasting temperature, roasting time, mass ratio of agents to ore and the types of leaching agents on the extraction of Nb, Y and Ce were investigated, and the roasting KHSO4–H2SO4–ore system was thought as an effective method to extract these valuable metals. It was found that the recovery of Nb, Y and Ce can, respectively, reach 90.20%, 97.22% and 98.41% in condition of roasting temperature of 300 °C, roasting time of 2 h, mass ratio of KHSO4-to-H2SO4 to ore of 0.5:1:1, particle size of − 74 μm (~ 95%), leaching solution of oxalic acid (30 g·L−1), leaching temperature of 90 °C and leaching liquid-to-solid ratio of 5:1. The leaching kinetics of the calcined Nb-bearing ore in oxalic acid solution was successfully modeled by chemical reaction model, and the apparent activity energy was obtained to be 14.16 kJ·mol−1. The results generated from this work will provide the fundamentals for extracting Nb, Y and Ce from a niobium-bearing ore of low grade and have potential applications value in future.