The repair material for converter is a refractory material used for repairing converter lining. The main raw materials are magnesia, binder, plasticizer and a small amount of water. Gunning technology is widely used in the local damaged area of ​​converter lining, especially the trunnion and slag line. Through dry gunning, semi-dry gunning or flame gunning, the refractory material is concentratedly sprayed onto the lining surface, so that the gunning material and the lining brick are sintered into one, and the lining is repaired. The repair material must have the characteristics of high temperature resistance, good adhesion, less material shedding, good sintering with the hot lining surface and corrosion resistance. In particular, the semi-dry gunning material, after mixing with an appropriate amount of water, is sprayed onto the working surface of the lining and quickly bonded and solidified. Its effectiveness is measured by the adhesion rate and the number of times it is used. Flame gunning is repaired in the absence of water by adding combustible materials and gases to achieve better adhesion and longer service life. Rongsheng Company has developed two types of large-surface hot repair charge: one uses fused magnesia and magnesium calcium as the main raw materials, and adopts a composite carbon and ceramic combination method, with a service life of up to 50 furnaces; the other is an environmentally friendly fast-burning large-surface self-flowing repair charge, which has a short sintering time, no pollution, and easy construction, and is suitable for high-efficiency environmental repair.