The invention relates to a method and a device for improving the surface quality of a cast blank of a
continuous casting machine by adding covering
slag. The device comprises a crystallizer, wherein a crystallizer liquid covering
slag adding
system is connected to a crystallizer opening in the upper part of the crystallizer; by means of the
system,
solid covering
slag is molten by using a
medium frequency induction heating technology and is then heated to a certain temperature, the outflow volume of liquid covering slag is controlled by adopting a stopper bar, and the liquid covering slag is added into the crystallizer after passing through a liquid covering slag
distributor and a guide
pipe, so as to form a full-liquid covering slag layer at the upper part of
molten steel in the crystallizer. Meanwhile, a crystallizer heat-insulation cover is additionally arranged at the upper part of the crystallizer to reduce
radiant heat loss at the upper part of the crystallizer. According to the method and the device disclosed by the invention, the liquid covering slag is added to the
continuous casting machine, and the addition amount of the liquid covering slag is controlled according to the thickness of the liquid covering slag layer, such that the surface quality of a continuously cast blank is improved; in addition, The method disclosed by the invention is a substitute method of a conventional
solid covering slag adding method for a
continuous casting machine, has universality and can be applied to various continuous
casting machines for, such as, square billets, round billets and plate billets.