La2O3 modified Al-TiO2-C grain refiner, preparation method thereof and commercial-purity aluminum refining method

The invention discloses a La2O3 modified Al-TiO2-C grain refiner, a preparation method thereof and a commercial-purity aluminum refining method. The La2O3 modified Al-TiO2-C grain refiner is composed of Al powder, TiO2 powder, C powder and La2O3 powder. The preparation method of the La2O3 modified Al-TiO2-C grain refiner comprises the steps that 1, the Al powder, the TiO2 powder, the C powder and the La2O3 powder are mixed and then processed on a star type ball mill through ball milling for 0.5-2 h; 2, a precast block with the diameter phi being 30 is pressed on a universal tester, wherein 85 KN pressure is used for block pressing; 3, the precast block is wrapped by aluminum foil, and air between the precast block and the aluminum foil is extruded for storage; 4, the precast block is sintered in a high-temperature sintering furnace; and 5, furnace cooling is carried out, then the sintered precast block is taken out, and therefore the prepared La2O3 modified Al-TiO2-C grain refiner is obtained. Relatively small and thin isometric crystals can be obtained when the La2O3 modified Al-TiO2-C grain refiner is used for refining commercial-purity aluminum; precipitated phases are TiC, Al2O3 and Al3Ti phases. A corresponding rare earth phase Al20Ti2La can be generated after the rare earth element La is added, and the appropriate amount of Al20Ti2La plays an important role in improving the refining performance of the Al-TiO2-C refiner.