What is Taphole Clay？

What is taphole clay？
Tap hole is very important part of blast furnace，where molten iron and slag go out .
Number of casts increased because of the application of intensive smelting technology and blast furnace to the large-scale, and the process conditions became more demanding. The tap hole would be blocked by clay to prevent coal gas from leaking once molten iron and slag have went out.
The clay belongs to unshaped refractories, is named tap hole clay. When the blast furnace is working, high-temperature slag, molten iron and high-pressure
coal gas  scouring and eroding frequently. What’s more,the bricking nearby the tap hole are easily damaged because of the impact of high pressure tap hole clay. So tap hole clay plays an important role in maintaining the service life of blast furnace.