Cast iron insulating coverant is primarily used to extend the solidification time of metal in the riser and serves the purpose of insulation and slag prevention. The appropriate time for its addition is between when the molten steel rises to 2/3 of the riser and the pouring stops, or it can be added after the pouring has ceased. The entire addition process must be completed before the riser's surface forms a crust.

Using cast iron insulating agents can effectively reduce the heat loss of metal liquid, extend the solidification time of the riser, enhance the riser's feeding effect, and is also simple and convenient to use with less addition required.