Pilot-scale recovery of rare earths and scandium from phosphogypsum and uranium leachates

Maxim Mashkovtsev,Pertti Koukkari,Risto Pajarre,Maxim Botalov,Vladimir Rychkov,Denis Smyshlyaev,Petteri Kangas,P.B Kowalczuk,J Drzymala

doi:10.1051/e3sconf/20160801026

Abstract

Ural Federal University (UrFU) and VTT have performed joint research on development of industrial technologies for the extraction of REM and Scandium compounds from phosphogypsum and Uranium ISL leachate solutions. Leaching-absorption experiments at UrFU have been supported with multicomponent solution modelling by VTT. The simulations have been performed with VTT’s ChemSheet/Balas program and can be used for speciation calculations in the lixiviant solution. The experimental work combines solvent extraction with advanced ion exchange methodology in a pilot facility capable of treating 5 m3 solution per hour. Currently, the plant produces cerium carbonate, lanthanum oxide, neodymium oxide and concentrate of heavy rare earth metals. A batch of 45 t solids has been processed with the gain of 100 kg’s of REM concentrate. A mini-pilot plant with productivity above 50 liters per hour has been applied to recover scandium oxide and REE concentrates from the uranium ISL solution. As the preliminary product contains radioactivity (mainly strontium), an additional decontamination and cleaning of both concentrates by extraction has rendered a necessity. Finally a purified 99% concentrate of scandium oxide as well as 99% rare earth concentrate are received.

Highlights

In the processing or Rare Earth Elements (REE) saline solutions containing large amounts of Fe, Al and other elements are typically formed
Based on the earlier studies [4,5,6], it was found that the highly crosslinked sulfonated resins adsorb poorly polymeric ions (Zr, Fe (III), etc.), mainly due to the sieve effect. These differences in the absorption and elution properties of different hydrocomplexes on crosslinked ion exchangers allow for enhanced separation of Zr, Fe, Al, Th, and REE ions without adding special complexing agents
Cations of the same charge those with smaller ionic radii are more prone to hydration and, have a greater influence on the selectivity with on strong acid cation exchangers

Summary

Introduction

In the processing or Rare Earth Elements (REE) saline solutions containing large amounts of Fe, Al and other elements are typically formed. The extraction of REE and Sc from those is an elaborate task by traditional chemical methods. For example in the industrial scale recovery of REE and Sc from these solutions the traditional method is deposition by ammonia, alkalis and anions such as F-, S2O42-, and PO43-. Disadvantages include large loss of REE (20-25%) [1, 2] as coprecipitating hydroxides of metals such as Fe(III), Al, Zr and Ti. In addition, waste waters caused by the large flow rates, chemicals used for precipitation and low regeneration rates are difficult to process. The received concentrates were subjected to additional purification to achieve decontaminated products

Methods

Results

Conclusion