THE INFLUENCE OF TRIBUTYL PHOSPHATE ON MOLYBDENUM EXTRACTION WITH SOLUTIONS OF DIBUTYL PHOSPHORIC ACID

Comparative investigations were carried out to study the influence of TBP on Mo extraction by HDBP solutions in xylene and TBP in xylene. The dependences of D(Mo) on HNO(3) concentration for both HDBP and D2EHPA have minima at about 3 mol/L HNO(3). This shows similar extraction properties of HDBP and D2EHPA. The presence of TBP in the solvent results in the reduction of Mo extraction and in an increase in the formal slopes of the falling and rising parts of the logD(Mo)-log[HNO(3)] curve from-0.5 and +2 up to-2 and +4. Solvent loading curves with Mo show that in the absence of TBP a molybdenum solvate with two molecules of HDBP is formed at low acidity. Anomalous increase in the maximum solvent loading in the presence of TBP is caused by the ability of TBP to extract Mo from oversaturated low acidity solutions following the acidic mechanism. Amolybdenum solvate with two HDBP molecules and one HNO(3) molecule is possibly formed at high acidity. A flowsheet for Mo recovery from HLW with HDBP-TBP solvent was tested in centrifugal contactors.