Excer process

A wet process is also utilized for the production of uranium(IV) fluoride, namely the EXCER process (Ion Exchange Conversion Electrolytic Reduction). In this process the ion exchange- or extraction-purified uranium(VI) solution is either electrolytically or chemically reduced to uranium(IV), which is precipitated with hydrofluoric acid as uranium(IV) fluoride hydrate (UF4 O.75H2O). This is subsequently dehydrated at 400 to 450°C. 

The recently developed Excer process of the U.S.A.E.C. aims to extract uranium from low-grade ore, purify it up to nuclear specification and convert to uranium tetrafluoride ready for metal production. The process is shown in Fig. 3.15 and is based first upon a sulphuric acid leach of the ore and anion absorption of uranium from the pulp. Elution is then by 2M sulphuric acid to give a solution containing about 10 to 20 g U/1. The uranyl sulphate is then reduced by metallic iron to uranous sulphate, diluted to an acidity of 0-5M and a second cycle of anion-exchange carried out. Absorption behaves similarly to that with uranyl ion, but ferrous ion is not... 

Fig. 3.15. Excer process for continuous extraction of uranium (Holcomb, R. R. and Higgins, I. R. Ref. 63).

Excer A process for making uranium tetrafluoride by electrolytic reduction of a uranyl fluoride solution, precipitation of a uranium tetrafluoride hydrate, and ignition of this. 

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