In order to improve the Mg removal from an A-380 molten alloy, mixtures of mineral silica and amorphous silica nanoparticles (SiO2(NP´s)) were tested. Mineral silica was enriched with 2.5, 5 and 10wt% of amorphous SiO2(NP´s). Before Mg removing, samples of mineral silica were impregnated with SiO2(NP´s) bymixed for 30 min in ethanol and then dried at 110°C for 24 h. The enriched mineral silica with nanoparticles was analyzed by scanning electron microscopy and transmission electron microscopy. The Mg removal was carried out injecting each mixture into the molten aluminum alloy at 750°C using argon as a carrier gas. The Mg content of the molten alloy was measured after different periods of injection time (each 10 min). It was found that the mineral silica with 10wt% of SiO2(NP´s) is the most efficient mixture, removing Mg from an initial content of 1.6 to a final content of 0.4wt%, in 70 min of injection. Moreover, thermodynamic predictions were carried out in the FactSage software in order to establish chemical equations occurring in the system.