METHOD FOR RECOVERING TECHNICAL-GRADE MOLYBDENUM FROM DILUTED ACID LEACING SOLUTIONS (PLS) THAT HAVE A HIGH ARSENIC CONCENTRATION AND ORIGINATE FROM METALLURGICAL WASTE

The invention relates to a method for recovering technical-grade molybdenum from diluted acid leaching solutions (PLS) that have a high arsenic concentration, said method comprises the following steps consisting in: (a) bringing a pre-filtered acid leaching solution (PLS), originating from the leaching of smelter dust, into contact with an anionic ion-exchange resin; (b) washing the loaded resin with water; (c) extracting the molybdenum from the ion-exchange resin with an alkaline ammonium regenerant solution at a pH value of between 8 and 12, in order to form ammonium molybdenum in solution; (d) washing the unloaded resin with water; (e) adding iron and/or magnesium salts to the recovered ammoniacal solution, in order to obtain a precipitate which is transferred to the arsenic abatement step and a solution containing ammonium molybdate in solution; (f) adding sulphuric acid to the arsenic-free ammoniacal solution in order to precipitate the moylbdenum in the form of ammonium molybdate in an acid environment at a pH value of between 1.5 and 4; (g) separating the precipitate formed by filtering the molybdate and re-circulating the solution obtained with the initial PLS solution; (h) calcining the separated precipitate in order to obtain ammonia and molybdenum trioxide; and (i) recovering the released ammonia for its subsequent use in the method as a recirculated regenerant solution. La presente invención reivindica un proceso para la recuperación de molibdeno grado técnico a partir de soluciones ácidas diluidas de lixiviación (PLS), altamente concentradas en arsénico, donde el proceso comprende las etapas de: (a) poner en contacto una solución acida de lixiviación (PLS) previamente filtrada proveniente de la lixiviación de los polvos de fundición con una resina aniónica de intercambio iónico; (b) lavar con agua la resina cargada; (c) extraer el molibdeno de la resina de intercambio iónico con una solución regenerante alcalina de amonio a un valor de p H entre 8 y 12, para formar molibdato de amonio en solución; (d) lavar con agua la resina descargada; (e) agregar sales de magnesio y/o hierro a la solución amoniacal recuperada, para obtener un precipitado el cual es llevado a la etapa de abatimiento de arsénico, y una solución que contiene el molibdato de amonio en solución; (f) agregar ácido sulfúrico a la solución amoniacal libre de arsénico, para precipitar el molibdeno en la forma de molibdato de amonio en ambiente ácido a un valor de p H entre 1,5 y 4;