Extraction of rare earth metals from deep sea nodule using H2SO4 solution

Leaching of rare earth (RE) metals from the Pacific Ocean sea nodule was carried out in H2SO4 medium. Preliminary study was performed to ascertain the existence of rare earth elements in the sea nodule crust. Concentration of H2SO4 and temperature were found as the key factors which enhance the dissolution rate of rare earth metals. The maximum average RE leaching efficiency of 83.03% was obtained using 3 M H2SO4. At the above condition, leaching of most of the RE was ≥ 90% and the remaining metals were; Ce 44.6%, La 55.3%, Nd 84.7%, Eu 85.8%, Pr 76.4% and Th 78.8%, in which the co-extraction of other base metals like Fe, Co, Ni, Cu was high. Dilute acid i.e. 0.2 M of H2SO4 and temp. 45 °C was found to be best for optimum extraction (57.6%) of total rare earth, where the co-extractions of other base metals (Cu, Co, Ni, Mn and Fe) are very less.

► Leaching of rare earth (RE) metals from Sea nodule was carried out by H2SO4 solution.
► This study ensures the occurrence of rare earth metals in Fe2O3 phase of nodule crust.
► Factors like [H2SO4] and temp. play key role on enhancing leaching rate of metals.
► Avg. and max. leaching efficiencies of total RE metal were ~ 83% and 90%, respectively.