Researchers Uncover Key Environmental Effects of Leaching Agents in Ion-Adsorption Rare Earth Ores

Strategic Insights -

In a new study, investigators have explored the environmental effects of leaching agents in the exploitation of ion-adsorption rare earth ores. Funded by the National Natural Science Foundation of China and the Natural Science Foundation of Jiangxi Province, the research highlights the importance of understanding the release behavior of heavy metals from soils under leaching conditions. The study, conducted by a team of researchers at the Jiangxi University of Science and Technology, demonstrates that the environmental risks of heavy metal pollution are predominantly concentrated in the middle to late stages of leaching.

Key Takeaways:

  • The research used laboratory column leaching experiments to investigate the effects of three leaching agents, (NH4)2SO4, Al2(SO4)3, and MgSO4, on the release and speciation transformation of heavy metal Pb in mining-affected soils.
  • The results showed a three-stage pattern in Pb release, characterized by slow release, a sharp increase, and eventual stabilization, with environmental risks predominantly concentrated in the middle to late stages of leaching.
  • Under 3% (NH4)2SO4 and 3% Al2(SO4)3 leaching conditions, Pb concentrations in soil increased significantly, with a higher proportion of labile fractions, indicating pronounced activation and risk accumulation.
  • MgSO4 exhibited a lower and more gradual Pb release profile, posing substantially lower pollution risks compared to (NH4)2SO4 and Al2(SO4)3.
  • Pb release under varying Al2(SO4)3 concentrations showed a nonlinear response, with a threshold effect in risk induction.

Statistics:

  • 3% (NH4)2SO4 and 3% Al2(SO4)3 leaching conditions led to a significant increase in Pb concentrations in soil (1.2x and 1.5x respectively).
  • MgSO4 exhibited a lower and more gradual Pb release profile, with a maximum Pb release of 0.5x compared to (NH4)2SO4 and Al2(SO4)3.
  • Under 3% Al2(SO4)3 conditions, both the proportion of bioavailable Pb and the Risk Assessment Code (RAC) peaked, with a residual fraction decline of 0.7x.

Sources:

  • Experimental Study on the Evolution Law of Pb in Soils and Leachate from Rare Earth Mining Areas Under Different Leaching Conditions. Earth, 2025,6(3):103.
  • Jiangxi University of Science and Technology, Ganzhou 341000, People's Republic of China.