PROCESS FOR RECOVERY OF TECHNICAL GRADE MOLYBDENUM FROM DILUTED LEACHING ACID SOLUTIONS (PLS), WITH HIGHLY CONCENTRATED ARSENIC, FROM METALLURGICAL RESIDUES

摘要

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.