The effect of uranium, radium and thorium speciation on the removal of radioactivity from acid mine drainage using ion exchange

Abstract

Acid mine drainage samples were collected from the central basin of the Witwatersrand basin in South Africa to study the removal of radioactivity. The samples were analyzed for gross alpha/beta activity, specific radionuclides, metals and anions concentration. The pH of the acid mine drainage samples was then varied and ion-exchange column experiments were carried out to remove radioactivity from acid mine drainage. The gross alpha activity ranged between 60 and 75 Bq/L and gross beta activity ranged from 56 to 70 Bq/L. The speciation of uranium, thorium and radium was modelled using Joint Expert Speciation System. The speciation had a big influence on the removal of radioactivity from acid mine drainage using ion exchange resin. The optimum pH was determined to be 8. Acid mine drainage samples treated at this pH showed gross alpha activity below the detection limit of 0.03 Bq/L for all samples and gross beta activities below 5 Bq/L for 9 of the 10 treated samples

Keywords:

• Uranium
• radium
• thorium speciation
• Joint Expert Speciation System
• acid mine drainage
• ion exchange

Acknowledgements

The Eco-Analytica Laboratory of the North-West University, is acknowledged for their assistance in the ICP-MS and anion analysis of samples. Purolite is also acknowledged for supplying the ion-exchange resins used in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The financial assistance of the National Research Foundation (NRF) toward this research is hereby acknowledged by the corresponding author. Opinions expressed and conclusions arrived at, are those of the author and are not necessarily to be attributed to the NRF.