Recovery of Thourium from Phosphogypsum by Acid Leaching
April 29-May 4, 2018
Phosphogypsum (PG), a waste material readily available in large quantities, is generated in the wet process of phosphoric acid production. Due to the contaminants in the material and the radioactivity of PG, the use of this material has limitations. South African phosphogypsum (from Phalaborwa) contains high levels of thorium that could be recovered for industrial use. The study was conducted to determine the best acid for leaching thorium from phosphogypsum; to investigate the effect of solid to liquid ratios and of concentration on the efficiency of the process; and to study the effect of contact time on the thorium recovered from the leaching process. Thorium was recovered from phosphogypsum by leaching the samples with strong acids under specified controlled and manipulated variables. 98% sulphuric, 32% hydrochloric and 55% nitric acid were compared to identify the best leaching reagent. The solid to liquid ratios studied were 2%, 5% and 10%. The acid concentrations investigated were 2 M, 5 M and 10 M. Nitric acid proved to be the best leaching reagent among the investigated acids, recovering 0.07486 g of Th/ kg of PG. The lowest concentration of 2 M recovered more thorium (0.06117 g of Th/ kg of PG); while a higher solid loading yielded more thorium (10% loading recovered 0.04453 g of Th/ kg of PG).
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Tebogo Mashifana, Thabo Falayi, Freeman Ntuli, and Jessica Sebothoma, "Recovery of Thourium from Phosphogypsum by Acid Leaching" in "Beneficiation of Phosphates VIII", Dr. Patrick Zhang, Florida Industrial and Phosphate Research Institute, USA Professor Jan Miller, University of Utah, USA Professor Laurindo Leal Filho, Vale Institute of Technology (ITV), Brazil Marius Porteus, Foskor-Mining Division, South Africa Professor Neil Snyders, Stellenbosch University, South Africa Mr. Ewan Wingate, WorleyParsons Services Pty Ltd., Australia Prof. Guven Akdogan, Stellenbosch University, South Africa Eds, ECI Symposium Series, (2018). http://dc.engconfintl.org/phosphates_viii/33