Phosphates to Acid-soluble Compounds

In order to proceed with the fractionation, the zirconium hafnium phosphates must be converted into acid-soluble compounds. Digestion of the moist phosphates with a mixture of sodium hydroxide and sodium peroxide yields a dense white peroxy compound, which can be washed free from the soluble phosphates, and which is soluble in acid with the evolution of oxygen. This reaction is utilized in the following procedure, except that 30 per cent hydrogen peroxide has been substituted for the sodium peroxide. 

The precipitated phosphate mixture is transferred to a 4-1. beaker and mixed thoroughly with water to give a 

The precipitate is subsequently transferred to a beaker and dissolved in sufficient 1 1 sulfuric acid to give 2 N sulfuric acid solution containing 2 to 5 per cent RO2 when finally diluted with water. The solution is then boiled to decompose the peroxide. A clear solution results if the precipitate has been washed free of phosphate if a precipitate appears, it is best separated from the mother liquor by centrifugation and re-treated in the prescribed manner. The final solution is analyzed for total oxide and Hf02. 

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