Protecting slag of round blank continuous-casting crystallizer and production method thereof

The invention discloses a protecting slag of a round blank continuous-casting crystallizer, comprising the chemical components in mass percent as follows (wt%): 25-35% of SiO2, 0.1-5% of MgO, 21-31% of CaO, 0.2-3% of Fe2O3, 3.5-11% of Al2O3, 2.5-9% of Na2O, 2.5-7% of F, 0-2% of Li, 0-4% of MnO, 1-10% of volatile matter and 8-22% of fixed C. By effectively adding a cheap electrolytic aluminium slag raw material into a formula of the protecting slag of the round blank continuous-casting crystallizer for use, chemical elements contained in the raw material, such as F, C, Na, Al etc., can replace or partially replace one or more kinds of raw materials of the chemical elements used in the formula of the protecting slag of the round blank continuous-casting crystallizer, and the quality performance of the product can reach and be up to the enterprise standard. In the practical production, a technical worker in the technical field manages to reduce the cost from various aspects; however, as the production field of the protecting slag is quite different from that of electrolytic aluminium, the electrolytic aluminium slag cannot be improved so as to turn waste electrolytic aluminium slag into wealth.