Iron recovery and rare earths enrichment from Bayan Obo tailings using Coal-Ca(OH)2-NaOH roasting followed by magnetic separation

Abstract

The recovery of iron and enrichment of rare earths from Bayan Obo tailings were investigated using Coal-Ca(OH)2-NaOH roasting followed by magnetic separation. The influences of roasting temperature, roasting time, coal content, milling time, Ca(OH)2 dosage and NaOH dosage on the iron and rare earths recovery were explored. The results showed that the magnetic concentrate containing 70. 01 wt. % Fe with the iron recovery of 94. 34% and the tailings of magnetic separation containing 11. 46 wt. % rare earth oxides (REO) with the REO recovery of 98. 19% were obtained under the optimum conditions (i. e., roasting temperature of 650 °C, roasting time of 60 min, coal content of 2. 0%, milling time of 5 min, and NaOH dosage of 2. 0%). The Ca(OH)2 dosage had no effect on the separation of iron and rare earths. According to the mineralogical and morphologic analysis, the iron and rare earths of Bayan Obo tailings could be utilized in subsequent ironmaking process and hydrometallurgy process.