Separação do molibdênio de tungstênio a partir de uma solução lixiviada de schelita.

Abstract

In the present work, the separation process of tungsten and molybdenum present in a schelite solution (mother solution) was studied, using the EXTRACTION process, considering the following variables: Extractant concentration, stirring time, rest and pH. D-2-ethylhexylphosphoric acid (D-2-EHPA) diluted in chloroform was used as an extractant. The extraction process was carried out using 12.5 ml of each phase in 125 ml capacity round bottom flasks fitted with Teflon caps and a vibrating (or pulsating) mechanical stirrer set to exert 360 vibrations. per minute. The room temperature was kept constant by means of air conditioning and the molybdenum and tungsten concentrations were measured in the aqueous phase using an atomic absorption device. As a first test, an optimal pH value was determined at which extraction becomes more efficient, offering a higher distribution coefficient for molybdenum (DM0). In agreement with the several studies already published regarding the subject, an optimal pH value of 1 to 2 was found. Once the pH and temperature conditions were defined, the influence of the stirring time and the necessary rest time were studied. equilibrium between the two phases formed, allowing a maximum level in the magnitude of the extraction. By setting the resting time, an ideal agitation time of 80 minutes was found, even varying the concentration of the extractant. The same result was achieved by setting the stirring time and varying the resting time. "In order to determine the stoichiometry of the representative reaction of the extractive process, experiments were carried out with varying concentrations of the extractant. It was concluded that for each mol of the cationic molybdenum species to be extracted, two moles of extractant is required. D-2-EHPA.