Hypereutectic high-chromium cast iron and suspension and modification composite treatment method thereof

The invention discloses hypereutectic high-chromium cast iron and a suspension and modification composite treatment method thereof. The hypereutectic high-chromium cast iron is prepared from, by mass, 3.5%-4.0% of C, 18%-25% of Cr, 0.3%-0.7% of Mn, 0.8%-1.2% of Si, 0%-0.05% of S, 0%-0.05% of P and the balance Fe. The treatment process comprises the following steps: 1) mixing, heating and melting waste steel, ferrochrome, ferrosilicon and ferromanganese, and then heating and deoxidizing to obtain hypereutectic high-chromium cast iron liquid; (2) pouring into a casting ladle, and refining primary carbides in the casting ladle by adopting a modification treatment method at the same time; (3) a slag remover is scattered above the hypereutectic high-chromium cast iron liquid, pouring is carried out after the temperature of the hypereutectic high-chromium cast iron liquid is reduced to 1360-1390 DEG C, and a suspending agent is added while pouring is carried out; and (4) after pouring, a pouring gate opening is cov