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This content will become publicly available on November 1, 2018

Title: Rare earths recovery and gypsum upgrade from Florida phosphogypsum

Phosphogypsum is a byproduct created during the production of industrial wet-process phosphoric acid. This study focused on recovering rare earth elements (REEs) from a Florida phosphogypsum sample and investigated the effects of removing detrimental impurities such as phosphorus pentoxide (P 2O 5), uranium (U) and fluorine (F) during the leaching process. Experimental results indicated that REE leaching efficiency increased rapidly, reached a maximum and then began to decrease with sulfuric acid concentrations ranging from 0 to 10 percent and temperatures ranging from 20 to 70 °C. At a sulfuric acid concentration of 5 percent and leaching temperature of 50 °C, REE leaching efficiency obtained a maximum value of approximately 43 percent. Increasing the leaching time or liquid/solid ratio increased the leaching efficiency. The leaching efficiencies of P 2O 5, U and F consistently increased with sulfuric acid concentration, temperature, leaching time and liquid/solid ratio within the testing ranges. A fine-grain gypsum concentrate, sized smaller than 40 μm, was separated from leached phosphogypsum through elutriation, in which the P 2O 5, U and F content levels were reduced by 99, 70 and 83 percent, respectively, from their content levels in fresh phosphogypsum.
 [1] ;  [2] ;  [2] ; ORCiD logo [3]
  1. Northeastern Univ., Shenyang (China); Florida Polytechnic Univ., Bartow, FL (United States)
  2. Florida Polytechnic Univ., Bartow, FL (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Minerals and Metallurgical Processing
Additional Journal Information:
Journal Volume: 34; Journal Issue: 4; Journal ID: ISSN 0747-9182
Society for Mining, Metallurgy & Exploration
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
58 GEOSCIENCES; Rare earth elements; phosphogypsum; leaching efficiency
OSTI Identifier: