Extraction of Molybdenum and Tangsten with D2EHPA and LIX63

Abstract

The extraction characteristics of molybdenum and tangsten were examined by using D2EHPA and LIX63 as an extractant. The method for separation of molybdenum and tangsten was investigated on the basis of solution chemistry of both metal ions.
Since molybdenum exists as the form of MoO₂²⁺ in acidic solutions, molybdenum can be extracted with D2EHPA and LIX63. On the other hand, tangsten does not form such cationic species and then no extraction of tangsten takes place with D2EHPA. In the extraction of molybdenum and tangsten from the equimolar solution of both metal ions, separation facter of 180 and 150 obtained in the use of D2EHPA and LIX63, respectively. When the tangsten concentration increases compared with the concentration of molybdenum in the aqueous solution, the extraction of molybdenum with D2EHPA is depressed and the extent of depression increases with an increase in the tangsten concentration. LIX63 can be applied to the aqueous solution containing high tangsten concentration, because the extraction of molybdenum is not almost depressed even in the presence of high tangsten concentrations.
The separation of molybdenum and tangsten in leach solutions of scheelite ores can be accomplished by the process where molybdenum is extracted and separated from the leach solution with LIX63 and then molybdenum is extracted again with D2EHPA from the stripped solution of the loaded LIX63 phase. Molybdenum can be easily stripped with diluted sodium hydroxide solution, although the stripping does not take place with mineral acid solutions of the concentration less than 6 normal.