When the sieved additive is used, the contents of iron and aluminium oxides in the extraction are greatly decreased, which is beneficial to making calcium phosphates with higher parity.

• 若采用本文所筛选的添加剂,用量约3%25,可大大降低浸取液中倍半氧化物含量,有制于制取纯度较高的磷酸钙盐。