Solving the arsenic problem to enable US cobaltite mining

image from scanning electron microscope shows crystalline scorodite formed in the electrochemical process.
SEM image of crystalline scorodite formed in the electrochemical process.

 

image and table show scattered electron microscope image and EDS analysis of crystalline scorodite formed in the electrochemical process.
EDS analysis of crystalline scorodite formed in the electrochemical process.

CMI researchers at Idaho National Laboratory conducted the research for this highlight

Innovation 
An electrochemical-based process was demonstrated for the isolation of As (as crystalline scorodite FeAsO4·2H2O), from a surrogate leachate of the domestic mineral cobaltite (CoAsS) at ambient pressure and 70°C.

Achievement

  • From a surrogate solution containing 20 g/L of As and 20 g/L Co, up to 95% of As was immobilized as scorodite, and 99% of the Co remained in the solution for downstream recovery and purification.
  • Crystalline scorodite characterization was verified through XRD, SEM-EDS, and RAMAN Spectroscopy.

Significance, Impact, and Next Step

  • Stabilization of As released upon recovering Co from the mineral cobaltite solves a long-standing environmental barrier to domestic cobalt mining.
  • Potential to replace energy- and chemical-intensive industrial processes.
  • Next step is to combine electrochemical dissolution of cobaltite with simultaneous scorodite formation.

Hub Target Addressed 
Unlocking unconventional resources of critical materials.

line graph shows Powder X-ray Diffraction that confirms formation of crystalline scorodite. 
Powder X-ray Diffraction confirming formation of crystalline scorodite.