Calcium aluminum ball is made of metal aluminum and highly active alumina. It first reacts with oxygen in molten steel to form a strong reducing atmosphere. The alumina contained in itself is combined with calcium oxide to form calcium aluminate slag system. The slag system has a melting point of about 1300 ℃ and has high sulfur capacity, which is conducive to the removal of sulfur from molten steel. In addition, the effect of making white slag is also very good.