Treatment of phosphoric acid sludge for rare earths recovery II: effect of sonication and flocculant solution temperature on settling rate

ABSTRACT

The effect of sonication on sludge exhibited a faster settling rate. Sonication creates acoustic cavitation preparing the slurry for better interaction with flocculant and generating faster settlement. Five samples of flocculants were conditioned at 25, 50, 60, 75 and 100° C for settlement. The flocculant conditioned at 60°C had the best performance in terms of settlement. However, further increase in temperature damaged polymer chains of the flocculant decreasing its effectiveness. ICP analysis showed sonicated samples trapped 11% more rare earth elements (REEs) in their residue and that temperature above 60º C is not favorable for the flocculant preparation in terms of coagulation.

KEYWORDS:

• Sonication
• flocculation
• phosphoric acid sludge
• settling
• rare earth elements

Acknowledgments

This research is part of a major project of the Critical Materials Institute (CMI), under subcontract number SC-14-392 funded by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. The guidance and leadership provided by Bruce Moyer, CMI Area Lead, and David DePaoli, CMI Project Lead, are highly appreciated. Substantial matching funds were provided by the Florida Industrial and Phosphate Research Institute, Florida Polytechnic University. The Mosaic Company is particularly acknowledged for their technical input, large in-kind support, and sample collection efforts. The authors would like to express gratitude to the following Mosaic employees and former employees for their help: Nicole Christiansen, Paul Kucera, Marcos Ortiz, Chris Dennis, Glen Oswald, Chaucer Hwang, Cameron Weed, and Gary Whitt.

• Effect of sonication on phosphoric acid sludge settling rate.

• Effect of the Flocculant Temperature solution on treatment of phosphoric acid sludge.

• Effect of flocculant Temperature solution on settling rate of phosphoric acid sludge.

• Optimum flocculant Temperature of Percol flocculants for recovery of REEs .

Additional information

Funding

This work was supported by the Critical Material Institute [SC-14-392] funded by the US Department of Energy; Office of Energy Efficiency and Renewable Energy; Advanced Manufacturing Office. Substantial matching funds were provided by the Florida Industrial and Phosphate Research Institute, Florida Polytechnic University.