Eluex process

Solvent extraction is applied either directly to the weakly acidic leach hquor (the method is known as the Purlex process in South Africa, and the Amex process in the USA) or to the strongly acidic eluate obtained from a preliminary ion-exchange treatment of the leach liquor (known as the Bufflex process in South Africa, and the Eluex process in the USA). In the Purlex process, a 5 /(i solution of a tertiary amine in kerosene is typically used to treat a leach liquor containing up to 1 g of uranium per litre (although concentrations as low as 0.04 g 1 may be encountered) at a pH value of 1 to 2. A modifier such as isodecanol (2-5%) is usually incorporated into the organic phase to prevent the formation of a third phase and to inhibit the formation of an emulsion. The extraction of uranium(VI) is usually considered to proceed according to reactions such as ... 

Disadvantages of sulfuric acid are (1) the low luranium concentration of eluate, (2) the high volume of eluant needed for complete elution, and (3) the high acid concentration to be neutralized if uranium is to be recovered from eluant by precipitation. The advantages of sulfuric acid are that it leaves the resin in the sulfate form, which adsorbs uranium more readily than the nitrate or chloride form, and it introduces no extraneous anions that must later be purged from the system. To facilitate use of sulfuric acid, the Eluex process, to be described later, was developed in this process uranium is removed from sulfuric acid eluate by solvent extraction rather than by neutralization and precipitation, and the acid is recycled to a subsequent elution cycle. 

Eluex process. Although it would be possible to recover uranium from the eluate leaving Fig. 

Figure 5.19 is a schematic flow sheet showing the Eluex process as used at the Federal-American Partners uranium miU, and the final steps for precipitating and calcining its uranium product. The Eluex process is a variant of the amine extraction (Amex) process described in Sec. 8.6. 

Amine systems achieve higher uranium purity than organophosphorus systems (due to the greater selectivity of amines for uranium) and have lower extractant losses due to their lower aqueous-phase solubility. SX is applied either directly to the weakly acidic leach liquor (also known as the Purlex or Amex process, Vaal River West, South Africa) or to the strongly acidic eluate from an ion-exchange preconcentration treatment of the leach liquor (the Bufflex or Eluex process, Vaal River South, South Africa) (Nicol et al. 1987). A more modem variation (such as at Southern Cross Resources Uranium One, South Africa) is to treat the ore by pressure leaching followed by SX. 

Bufflex [from Buffelsfontein (South Africa), extraction] A process for extracting uranium from its ores, using a solution of an amine (Alamine 336). It was developed in South Africa, and was later replaced by Purlex. See also Eluex. 

Eluex An early process for extracting nraninm from its ores, using both ion-exchange and solvent extraction. Developed by the National Lead Company, United States. 

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