Rare earth element stripping from kaolin sands via mild acid treatment

Max Koch, Michael Paper, Thomas B. Brück, Tom Nilges

Research output: Contribution to journalArticlepeer-review


Due to their chemical and physical properties, rare earth elements (REEs) are essential in modern applications such as energy conversion or IT technology. The increasing demand for these elements leads to strong incentives for REE recovery and induces the exploration of new, alternative sources for REEs. Accessing REEs from clay minerals, in our case kaolinite, by an elution process is a promising method. The present study investigates the potential application of REE recovery through elution with different mineral acids (HNO3, H2SO4, and HCl) in a microwave process. The material used in this study—residues from an industrial kaolin production process—contained 2.47 g/kg REEs which is a significant amount for REE recovery. The ability of various mineral acids to solubilize metals was studied to assess the REE content of this residual resource. Around 1.87 g/kg of REEs was eluted from industrial kaolinite residues in hydrochloric acid, 1.71 g/kg in sulfuric acid, and 1.13 g/kg in nitric acid.

Original languageEnglish
Article numbere3018
JournalAsia-Pacific Journal of Chemical Engineering
Issue number2
StatePublished - 1 Mar 2024


  • elution
  • extraction
  • kaolinite
  • process data
  • rare earth element recovery
  • rare earth elements


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