Recovery of rhenium and molybdenum from a roaster fume scrubbing liquor by adsorption using activated carbon

Activated carbon was used to adsorb and concentrate rhenium and molybdenum from liquors (pH 6-8) produced from a pilot plant set up to scrub a fume generated by a molybdenite roaster. The kinetics of adsorption of Re and Mo relating the loading of Mo or Re (Q(t)) to concentration at time t (C-t) and carbon concentration (X) follows the rate equation: Q(t) = kC(t) t(mLog(X)) where k is the rate constant, m is 0.90 and 1.0 for Mo and Re, respectively. The adsorption follows the Freundlich isotherm and is influenced by temperature and solution pH. The elution of metal values from the 300-400 g/L carbon loaded with 14.4 mg/g Re and 42 mg/g Mo by 1 M NH4OH at 95 degrees C could produce a concentrated liquor containing similar to 2.8-3.2 g/L Re and similar to 0.6-0.8 g/L Mo after 4 h (at 50-68% metal recovery). The batch elution of the same loaded carbon at 100 g/L concentration yielded a liquor of 1.2 g/L Re (at 91.5% elution efficiency) and 300 mg/L Mo (at 80% elution efficiency). Stripping of Re using NaOH (1-3 M) at 95 degrees C is not as effective as with NH4OH. (C) 2012 Elsevier B.V. All rights reserved.