At present, the slag blocking methods commonly used in domestic slag blocking machines include: slag ball method, slag blocking method, slag bar method and invisible slag blocking technology.
(1) Slag Limiting Ball method: The principle is to use the slag ball density between steel and slag (generally 4.2～4.5g/cm3), block the taphole at the end of tapping to block the slag from flowing into the ladle Inside. The slag blocking ball is generally spherical, and as long as it can meet the process requirements, the structure is simple and the cost is low. However, since the slag ball usually arrives at the taphole in a wave-by-flow manner, the slag ball sometimes cannot smoothly reach the taphole due to the high viscosity of the steel slag. In addition, since the circular slag ball completely falls on the taphole, the probability of premature sealing of the taphole is significantly increased, and the yield of molten steel is lowered, so the reliability of the slag ball is unsatisfactory.
(2) Slag Stopper Dart method: The slag stopper is a rod-oriented, steerable refractory product, which is gyro-shaped and has a density similar to that of the slag ball. It can float between 4.5 and 4.7 g/cm3. The steel slag interface, along with the tapping process, gradually blocks the taphole and achieves the effect of suppressing the eddy current and slag blocking of the molten steel. However, due to the accuracy of the delivery and the timing of the investment, it is difficult to guarantee the slag blocking effect.
(3) Slag bar method: The method is that the slag bar is suspended on the arm and can move freely in the furnace. When the tapping is about to end, the taphole is blocked from the furnace to achieve the purpose of slag blocking, but The operation and maintenance of this device is more complicated.
(4) Invisible slag blocking technology Because the slag blocking ball and other tangible slag blocking slag, the material consumption is high, the slag blocking effect is not ideal, and many steel mills at home and abroad have adopted the invisible slag blocking technology. From the development trend of slag blocking technology, domestic and foreign countries are gradually developing from the physical slag blocking method to the invisible slag blocking method.