Demineralization with ammonium

Carlson and Nielsen (C3) described the pilot and full-scale plant separation of an ore containing more than 30% combined columbium and tantalum oxide using a sulfuric-hydrofluoric acid leach and methyl isobutyl ketone (MIBK) as solvent in pulsed columns. The —200 mesh columbite-tantalite ore was digested with 70% HF until the combined (Ca + Ta)20s in the leach liquid reached 3 Ib/gal at which time it was diluted to 15N free acid and clarified by filtration. This solution was contacted countercurrently in the pulsed column where Ta and Cb were extracted by MIBK. Columbium was stripped from the organic with demineralized water which diluted the free acid in the solvent, making possible the transfer of all the Cb the Ta-loaded solvent was then stripped with demineralized water causing the transfer of Ta to the aqueous phase. The oxides were then precipitated with 28% ammonium hydroxide solution. Conversion to the respective oxides was by calcination of the precipitates. 

The diuranate is then reduced to UO2 with hydrogen at 820°C. In the third, AUC (ammonium uranyl carbonate) process, developed in West Germany by Nukem, streams of gaseous UF, CO2, and NH3 are fed batchwise into demineralized water, whereby (NH4)4U02 (003)3 is precipitated. The AUC is converted batchwise to UO2 by contacting it with steam and hydrogen at 500°C in a fluidized bed, with recovery of CO2 and NH3. Subsequently, steam at 650°C is supplied to the fluidized bed to reduce fluorine content to 50 to 60 ppm by pyrohydrolysis. 

Ammonium chloropalladite (0.1 mg. Pd/ml.). Dissolve 133.6 mg. of ammonium chloropalladite in 450 ml. of demineralized water acidified with 5 ml. of concentrated H2SO4. Dilute to 500 ml. Dilute this solution 1 1 before using as an internal standard. 

Wash solution II (Ammoniacal precipitation). Dissolve 0.5 gram each of ammonium chloride and ammonium sulfite, and 2 grams of thioacetamide in 1 liter of demineralized water. Adjust the pH to 8.0 with IN ammonium hydroxide. 

TABLE 19.2. Average Electrokinetic Transport Parameters for Sulfate, Nitrate, Phosphate, and Ammonium in Sandy Soil Saturated with Demineralized Water... 

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