Assay of Minerals and Uranium Ores

Several analytical methods have been deployed for the determination of uranium in ores. Among the older methods that were used are radiometric methods that were already used over 50 years ago for ore sorting (Mal tsev 1960), titrimetric methods in which the nraninm content in the ore was determined with ferrous ion-phosphoric acid reduction (Hitchen and Zechanowitsch 1980), colorimetric methods where complexes of nraninm are formed with standard arsenazo 111 (Onishi and Sekine 1972), exotic siderophores (Renshaw et al. 2003) reagents and instrumental neutron activation analysis (INAA) based on measurement of Np in the ore (Chaudhry et al. 1978) in addition to nnmerons other approaches. Many modem techniques are now employed for destrnctive and nondestructive determination of uranium in ores. 

A simple spectrophotometric (or colorimetric) method for the determination of uranium in perchloric acid based on the arsenazo-III complex was described (Khan et al. 2006). While azo-dyes may be oxidized by nitric acid, they are more stable in perchloric acid and organic interferences are effectively eliminated by this acid media. Standards of uranium and ore samples were weighed and decomposed in Teflon beakers with a 1 1 HNOjiHF mixture. The uranium was then extracted from the nitrate solution by liquid-liquid extraction with TBP in methyl isobutyl ketone (MIBK). The uranium 

Highlights The uranium content in ore samples can be assessed by nondestructive methods based on gamma spectrometry or neutron activation or by destructive methods that are usually considered to be more accurate and sensitive. The generic 

FIG U RE 2.6 A generic flowchart of the preparation of ore samples for determination of the uranium content. 

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