Preparation method of aluminum-manganese intermediate alloy

The invention relates to a preparation method of an aluminum-manganese intermediate alloy. The preparation method comprises the following steps: (1) transferring molten aluminum to a pre-heated line frequency furnace, and adding uniformly mixed potassium chloride and sodium chloride into the molten aluminum of the line frequency furnace when the molten aluminum is heated to 700-740 DEG C; (2) adding metal manganese sheets in 6-8 batches based on 24-26% of weight of the molten aluminum when the temperature of the molten aluminum in the line frequency furnace reaches 1250-1300 DEG C; (3) blowinga deslagging agent which accounts for 0.1-0.2% by weight of the molten aluminum into the molten aluminum by nitrogen to deslag primarily; (4) refining the molten aluminum through a powder spraying refiner, and then adding the deslagging agent which accounts for 0.04-0.06% by weight of the molten aluminum into the molten aluminum after refining to deslag secondarily; and (5) after secondary deslagging, continuously stirri