Pre-molten low-melting point composite calcium aluminate desulfurizer and its prepn

The invention discloses a kind of premelt-type, low-melting point, calcium aluminate complex desulfurizing agent and its preparation method, which is prepared according to the below components and proportion (weight): aluminum alum earth (calculated according to the Al2O3 content) 30-60%, and calcium oxide 40-70%. In advance perform passivating treatment on calcium oxide, then mix all the components according to the required proportion, then smelt them in the electric stove or the reflecting stove, then cool them, and by crashing, prepare the particle-shape or powder-shape desulfurizing agent. By the premelting treatment, the melting point of desulfurizing agent lowers to 1250-1400 centigrade, which obviously raises its desulfurizing rate in the molten iron molten steel and shortens the reactive time and production cycle.