Development of a pilot plant for the removal of rhenium from molybdenum trioxide.

Reagent grade molybdenum trioxide used as a target material for the preparation of Tc-99m pharmaceuticals contains trace amounts of rhenium. A simple charcoal adsorptions process has been developed to remove rhenium selectively from molybdenum before neutron irradiation. Details are given of the design and operation of a pilot plant in which 17 kg of molybdenum trioxide was produced having a rhenium content of less than 1 x 10 -6 mu g g -1. Although contamination of the Tc-99m by inactive rhenium and 188 Re was effectively eliminated 188 Re resulting from the irradiation of tungsten impurity in the molybdenum trioxide target was still present