Leaching effect of bio-surfactants on rare earth elements in raw ores

The effects of saponin concentration, solution pH value, particle size and solid-liquid ratio on the leaching efficiency of rare earth ores were investigated in leaching experiment by using saponin, a bio-surfactant, in order to realize the non-ammonium leaching of the ion-type rare earth ores in South China. The results showed that the leaching efficiency of saponin to rare earth reached 76.78 % after they were oscillated for 24 hours when the concentration of saponin was 50 g/L, pH of solution was 5.5 and solid solution ratio was 1:15(g/ml, similarly hereinafter). In addition, the cumulative washing efficiency of column leaching by using saponin reached 43.16 %, which was less than 1/2 of that by using ammonium sulfate. The reason was that the leaching efficiency of saponin to rare earth ores was affected by the properties of the solution and raw ores, velocity and other factors, leading to the low reaction and long tail period.