Extraction of molybdenum (VI) from nitric acid medium and its recovery from Gattar granite ore using CYANEX 923 in kerosene

This paper describes the extraction of molybdenum (VI) from aqueous nitric acid solution by trialkylphosphine oxide (CYANEX 923) in kerosene as diluent with 15% (v/v) cyclohexane as modifier. The effects of the different parameters on the extraction process such as nitric acid, CYANEX 923, hydrogen ion, nitrate ion and Mo (VI) concentration, as well as temperature, were separately investigated. The stoichiometry of the extracted species was found to be Mo(NO3)2·(OH)2·2CY, (where CY denotes CYANEX 923), based on the slope analysis method applied on the obtained results and supported by the IR-measurements. The loading capacity of CYANEX 923 was found to be 0.015 mole of Mo (VI) per mole extractant. The stripping investigations were carried out with different stripping agents and the maximum stripping reached 99% with 2 M sodium acetate. In order to test the viability of the used extraction system for the extraction of Mo (VI) from its ores, an application study was carried out on the Gattar granite ore. After leaching the ore with nitric acid and hydrogen peroxide mixture, Mo (VI) was extracted from 1 M nitric acid with 0.35 M CYANEX 923 at O/A phase ratio of 1. Although the extraction of Mo (VI) reached 94% with different extraction percents of other interfering ions, the selective stripping of Mo (VI) from these ions with 2 M Na-acetate indicates the efficiency and selectivity of the proposed process for the recovery of molybdenum from its ores.