Tap hole clay is a kind of refractory materials being used to plug the tapping hole. Now it can be divided into two major kinds: water tap hole clay and water-free taphole clay . The former is mainly used in the small and medium blast furnaces with lower top pressure, while the latter is mainly used higher top pressure large, medium blast furnaces BF.
The tap hole clay composition has two parts- refractory aggregate and binding agent. Refractory aggregate refer to alumina oxide, mullite, flint clay such refractory raw materials and coke, mica such modified materials. The binding agent have water or tar pitch and phenolicresinand so on. And it will mix with the SiC, Si3N4, swellingagentetc. The aggregate is composed of a matrix according to a certain particle size and weight, and it has a certain degree of plasticity under the adjustment of the binder, so that the molten iron can be blocked by the taphole clay into the iron hole.
Those that use water as the binding agent are called water taphole clay, while using organic materials such as tar, resin as binding agent are named as water-free tap hole clay.
The main functions of tap hole clay:
1. Block the tap hole, which request the clay to have good filling and sintering properties.
2. Stable tapping, requires taphole clayto be easy to open the taphole and resistant to erosion and scouring
3. To protect the hearth, the taphole clayis required to have no cracks when it is heated quickly, and the bonding strength of the new and old gun mud is high
4. The opening performanceof taphole clayis good, the opening machine bit is easy to drill
5. Moderate plasticity, convenient for taphole clay operation.
6. Good volume stability, small volume change at high temperature, no molten iron leakage due to shrinkage